EN 61191-1:2013 E English version Printed board assemblies - Part 1: Generic specification - Requirements for soldered electrical and electronic assemblies using surface mount and rela
Order of precedence
General remark
In case of any discrepancies between this standard and the referenced applicable standards, the provisions of this standard will prevail Nonetheless, this standard does not override any existing laws and regulations.
Conflict
In cases where there is a conflict between this standard and the approved assembly drawings, the approved drawings will take precedence If the assembly drawings are not approved, any discrepancies must be submitted to the designated user activity for approval Once approved, the changes will be documented on the assembly drawings, which will then govern the assembly process.
Conformance documentation
According to the standard, any documentary evidence supporting conformance claims must be retained for at least two years from the date of occurrence and should be available for inspection, as outlined in ISO 9001.
Interpretation of requirements
The classification of products based on levels and end use allows users to distinguish between performance requirements When users choose to adhere to the mandatory standards, specific conditions must be met.
• unless otherwise specified by the user, the word "shall" signifies that the requirements are mandatory,
Deviations from any mandatory "shall" requirements necessitate written acceptance from the user, such as through assembly drawings, specifications, or contract provisions The term "should" signifies a recommendation or guidance, while "may" indicates an optional scenario Both "should" and "may" reflect non-mandatory situations, whereas "will" conveys a declaration of purpose.
Classification
This standard acknowledges that electrical and electronic assemblies are classified based on their intended end-item use It establishes three general end-product levels to account for variations in producibility, functional performance requirements, and the frequency of verification through inspection and testing.
It is important to note that equipment may overlap between different levels The user, as outlined in section 3.5, is tasked with identifying the appropriate level for the product The contract must clearly define the required level and specify any exceptions or additional requirements as necessary.
Includes consumer products, some computer and computer peripherals, and hardware suitable for applications where the major requirement is function of the completed assembly
Level B: Dedicated service electronics products
The article discusses the necessity for high-performance communications equipment, advanced business machines, and instruments that require longevity and reliable service, although uninterrupted operation is not essential It emphasizes that these devices are typically used in environments that do not contribute to their failure.
Level C: High performance electronics products
All equipment essential for continuous performance or on-demand functionality is crucial, as any downtime is unacceptable This is particularly important in environments that may be exceptionally harsh, where the equipment must operate reliably when needed, such as in life support systems and other critical applications.
Defects and process indicators
Table 2 outlines unacceptable defects that necessitate actions such as rework or repair The manufacturer must also identify and document additional risks on the assembly drawing Besides the defects in Table 2, any anomalies or deviations from "shall" requirements are classified as process indicators and should be monitored when they occur, although their disposition is not mandatory.
Workmanship requirements shall be consistent with IPC-A-610E, and match the level of classification identified in 4.3.
Process control requirements
This standard mandates the application of process control methodologies throughout the planning, implementation, and evaluation of manufacturing processes for soldered electrical and electronic assemblies The strategies, tools, and techniques can be adapted in various sequences based on the specific company or operational variables, ensuring that process control aligns with end-product requirements Manufacturers may be exempt from certain quality conformance evaluations and inspections outlined in this standard, provided they have objective evidence of a robust and up-to-date continuous improvement plan, as referenced in section 13.3.
Requirements flowdown
Manufacturers and suppliers must enforce the applicable requirements of this standard on all relevant subcontracts and purchase orders Any deviations from these requirements are only permitted if they have received prior approval from the user.
This standard does not apply to the procurement of off-the-shelf assemblies or subassemblies unless stated otherwise However, manufacturers of these items may choose to comply with the standard as they see fit.
Physical designs
Design requirements
Some structural and layout design requirements are given in the following subclauses.
New designs
The layout of the printed board and the mechanical and thermal structure of the electrical/electronic assembly should adhere to relevant design standards, such as IEC 61188-5-1, or be approved by the user If a manufacturer can demonstrate that a revised layout enhances end product quality in line with these standards, both the user and manufacturer must agree on the modifications, leading to an appropriate update of the layout.
Existing designs
The requirements of this standard should not be the only reason for redesigning an approved design However, if changes to existing electronic or electrical designs affect hardware configuration, a review and user-approved modifications are necessary to ensure maximum compliance Any design changes proposed by the manufacturer must receive user approval, but the user is not obligated to accept these changes, even if they lead to compliance with the standard and the production of quality end products.
Visual aids
Line drawings and illustrations are depicted herein to assist in the interpretation of the written requirements of this standard The written requirements take precedence.
Proficiency of personnel
Design proficiency
The design facility must maintain documentation proving that all technical workforce personnel have received formal design training This training is essential regardless of whether the personnel are directly responsible for electronic or electrical product design, in accordance with ISO 9001 standards.
Manufacturing proficiency
Before starting work, all instructors, operators, and inspection personnel must demonstrate proficiency in their tasks Documentation of this proficiency must be kept and accessible for review, including training records for relevant job functions, testing results according to established standards, and outcomes from regular proficiency assessments, in accordance with ISO 9001 and IPC-A-610E.
Electrostatic discharge (ESD)
The ESD control program must comply with IEC 61340-5-1 and IEC/TR 61340-5-2, ensuring documented procedures for electrostatic discharge control to protect sensitive electrical and electronic components This program should be upheld during various stages, including the receipt and testing of incoming items, storage and kitting of boards and components, manufacturing and rework processes, inspection and testing cycles, as well as the storage and shipping of finished products, and during transport and installation.
Procedures for analysis of failures arising from ESD shall be documented and be available for review by an authorized inspectorate.
Facilities
General
Maintaining cleanliness in all work areas is essential to prevent contamination and deterioration of soldering tools, materials, and surfaces To ensure a safe and hygienic environment, eating, drinking, and the use of tobacco products or illegal drugs are strictly prohibited in the workspace.
Environmental controls
The soldering facility should be enclosed, temperature and humidity controlled, and maintained at a positive pressure.
Temperature and humidity
When relative humidity drops to 30% or lower, manufacturers must ensure that electrostatic discharge control is sufficient and that adequate moisture is available for effective flux performance and solder paste applications To maintain operator comfort and solderability, temperatures should be kept between 18 °C and 30 °C, with relative humidity not exceeding 70% Additionally, it is important to assess the necessity for stricter temperature and humidity controls for optimal process management.
Lighting
Illumination at the working surface of manual soldering and inspection stations shall be
Field conditions
In field operations where achieving controlled environmental conditions is challenging, it is essential to implement special precautions to enhance the quality of solder connections and reduce the impact of the uncontrolled environment on hardware operations.
Clean rooms
The assembly of electronics often requires clean rooms to meet production performance standards The specific class of clean room needed should be determined through agreement between the user and the manufacturer.
Assembly tools and equipment
General
The manufacturer must ensure the proper selection and maintenance of tools and equipment for preparing and soldering components and conductors It is essential that these tools are chosen to prevent any damage during use and are kept clean, free from dirt, grease, flux, oil, and other contaminants Additionally, soldering irons and equipment should be selected to provide effective temperature control and protection against electrical overstress (EOS) or electrostatic discharge (ESD).
Process control
To ensure compliance with section 4.12 and the objectives of Annex A, it is essential to implement appropriate process controls The detailed requirements outlined in Annex A are mandatory Additionally, assembly tools and equipment must be used according to a documented process that is accessible for user review, and they should clearly demonstrate the process parameters specified in the process documentation.
Overview
The materials utilized in soldering processes must adhere to the specifications outlined in this standard Due to potential incompatibilities among certain material and process combinations, it is the manufacturer's responsibility to choose the appropriate materials and processes to ensure the production of acceptable products.
Solder
Solder alloys must comply with IEC 61190-1-3 standards However, any alloy that meets the product's service life, performance, reliability, or regulatory requirements can be utilized, provided that all other conditions of the standard are satisfied and mutually agreed upon by the user and manufacturer.
Flux
Flux shall be tested and classified in accordance with IEC 61190-1-1 or equivalent, into one of the following three types:
L = low or no flux/flux residue activity;
M = moderate flux/flux residue activity;
H = high flux/flux residue activity
For assembly soldering, it is recommended to use Types L or M flux In cases where the flux residue will remain and not be cleaned (no-clean), an L flux that complies with the requirements of 9.6.9 without cleaning (C00) is advised, as detailed in section 9.6.3.2.
Inorganic acid fluxes and type H fluxes are suitable for tinning terminals, solid wire, and sealed components, but inorganic acid fluxes are not recommended for assembly soldering Type H fluxes can be utilized for soldering under an integrated system that includes fluxing, soldering, cleaning, and cleanliness testing, provided that either the user approves their use or there is available data demonstrating compliance with the testing requirements of Annex B.
When type H flux is used, cleaning is mandatory
When using liquid flux alongside other fluxes, it is essential to ensure chemical compatibility with those materials Additionally, the flux in cored solder must comply with the specified subclause, while the percentage of flux in cored solder remains optional.
Solder paste
Solder paste, solder powder and flux constituents shall meet the requirements of 5.2 and 5.3 and should be evaluated in accordance with IEC 61190-1-2 to meet the assembly process requirements.
Preform solder
Preform solder shall meet all applicable requirements in 5.2 and 5.3.
Adhesives
Adhesive materials used for attachment of other than surface mounted components shall be suitable for the application and compatible with the assembly.
Cleaning agents
General
When selecting cleaning agents for removing grease, oil, wax, dirt, flux, and other debris, it is essential to choose those that effectively eliminate flux residue and particulate contaminants These agents should be free from aggressive chemicals to prevent degradation of the materials and parts being cleaned Additionally, the cleaning process must ensure that the assembly complies with the cleaning requirements outlined in section 9.6.
Cleaning agents selection
Cleaning agents and mixtures of cleaning agents shall conform to all appropriate specifications and references Mixtures of cleaning agents may be used provided they are suitably stabilized or inhibited
Chlorinated solvents are prohibited, and the preferred options for cleaning applications are water, water/alcohol mixtures, or terpenes All cleaning solvents must adhere to relevant health, safety, and environmental regulations.
Polymeric coatings
General
The detailed requirements for polymeric materials are defined in the following subclauses.
Solder resists and localized maskants
Polymer solder resist coatings and temporary maskants must comply with IEC 61249-8-8 standards, ensuring they do not compromise solderability or the integrity of the substrate and printed wiring These materials should effectively prevent solder flow to masked areas and remain compatible with printed board base materials, conductive materials, intended fluxes, adhesives, and any conformal coatings applied later Additionally, if used temporarily, they should be easily removable without leaving harmful residues that could affect the printed board's conformal coating or assembly integrity.
Conformal coating and encapsulants
Conformal coating requirements for assemblies must align with the approved assembly drawing, detailing the specific type of coating material If edge coating is indicated, it must comply with section 11.2.2.7 Additionally, encapsulants used should be appropriate for the application and compatible with the assembly.
Spacers (permanent and temporary)
Mechanical stand-offs must be made from materials that can endure soldering processes and allow for inspection of solder joints, as outlined in section 13.2.2.3 Additionally, spacers should be capable of withstanding temperatures resulting from the self-heating of components The specific location, configuration, and material of these stand-offs must be detailed in the relevant documentation.
Chemical strippers
Chemical solutions, pastes, and creams for stripping solid wires must not degrade the wire or the materials being cleaned The cleaning agents should be free from aggressive chemicals Wires must be neutralized and cleaned of contaminants following the suppliers' instructions and should remain solderable as per standard 6.3.
Heat shrinkable soldering devices
Heat shrinkable soldering devices must be self-sealing and effectively encapsulate the solder connection Braided shield terminations should adhere to the specific work instructions provided by manufacturers, which align with the approved assembly drawing requirements Notably, these self-sealing devices are not subject to the cleaning requirements outlined in section 9.4.
6 Components and printed board requirements
General
Electronic and mechanical components, along with printed boards, must meet the specifications outlined in the procurement document, with the assembly manufacturer responsible for ensuring compliance It is essential that the selected components and printed boards are compatible with all materials and processes utilized in the assembly manufacturing.
NOTE For further information, see IEC 62326-1, IEC 62326-4, IEC 62326-4-1 and IEC/PAS 62326-7-1.
Solderability
Parts solderability
The supplier is responsible for ensuring the solderability of parts, which must comply with the specifications agreed upon with the manufacturer Electronic and mechanical components, as well as wires, should meet solderability standards when tested according to IEC 60068-2-20, IEC 60068-2-58, or equivalent methods Additionally, printed boards must fulfill the requirements outlined in IEC 61189-3 or equivalent testing standards.
Before accepting parts for storage or use, manufacturers must verify that the solderable components have undergone solderability testing according to a defined sampling plan and meet the relevant solderability specifications Users are responsible for specifying the necessary solderability standards Additionally, storage conditions must adhere to class 1K2 of IEC 60721-3-1 and IEC 61760-2.
Reconditioning
When tinning and inspection is performed as part of the assembly process, that tinning operation can be used in lieu of solderability testing (see 6.3).
Solderability testing of ceramic boards
Metallic elements of ceramic printed boards shall be tested for solderability as specified in IEC 61189-3, or by using an equivalent method.
Solderability maintenance
General
The manufacturer must guarantee that all components, leads, wiring, terminals, and printed boards meet the solderability requirements before beginning hand or machine soldering operations Additionally, the manufacturer is responsible for implementing procedures to reduce solderability degradation.
Preconditioning
Component leads, terminations, and terminals may be preconditioned (e.g hot solder dipped) to provide solderability maintenance.
Gold embrittlement of solder joints
To reduce the effects of solder embrittlement caused by gold-plated components, the gold content in any solder joint must be limited to a maximum of 1.4% of the total solder volume, which corresponds to 3% by weight.
If there is verifiable evidence indicating that there are no issues related to gold solder embrittlement or other metallic surface finish solder joint integrity problems in the soldering process, the subsequent requirements may be waived.
6.3.3.2 Gold on component and piecepart leads terminations
Manufacturers must ensure compliance with presoldering requirements by either pre-tinning all gold-plated leads, terminations, and terminals or removing gold from the surfaces intended for soldering Additionally, any residual gold present before soldering must not exceed the limits specified in section 6.3.3.
Tinning of leads/terminations shall not adversely affect the components A double-tinning process or dynamic solder wave should be used for effective gold removal
The gold removal process can be bypassed for components intended for dip, wave, or drag soldering, given that there is adequate gold thickness to satisfy the solderability criteria outlined in section 6.2, and that the soldering process provides sufficient time, temperature, and solder volume to fulfill the requirements specified in section 6.3.3.
6.3.3.4 Gold on printed board lands
The volume of gold deposited on any printed board land intended for soldering components or terminals shall not cause the limits given in 6.3.3 to be violated.
Tinning of non-solderable parts
Components, terminations, and printed boards that fail to meet solderability standards must undergo rework through hot solder dip tinning or other appropriate methods before soldering The reworked components should comply with the specified requirements, excluding steam aging It is essential that tinned wire areas do not cover the wire strands with solder, and solder wicking under wire insulation should be minimized Additionally, heat sinks must be used on the leads of heat-sensitive components during the tinning process.
Solder purity maintenance
Solder used for gold removal, tinning, and machine soldering must be regularly analyzed, replaced, or replenished to meet the limits outlined in Table 1 The analysis frequency should be based on historical data or conducted monthly If contamination levels exceed the specified limits, the intervals for analysis and replenishment should be reduced Additionally, comprehensive records of all analyses and solder bath usage, including total usage time, replacement solder amounts, and area throughput, must be maintained for each process system.
Table 1 – Solder contamination limits; maximum contaminant limit (percentage by weight)
(lead/wire tinning) Assembly soldering
The tin content in the solder bath must remain within ±1.5% of the specified nominal value, with testing conducted at the same frequency as for copper and gold contamination The remaining composition of the bath should consist of lead or the other specified materials.
The total of copper, gold, cadmium, zinc and aluminum contaminants shall not exceed 0,4 % for assembly soldering
When metals are part of the solder alloy used in the process, they are not classified as contaminants For the Sn62Pb36Ag2 alloy, the acceptable limits range from 1.75% to 2.25% This does not apply to processes utilizing Sn60Pb38Bi2 (alloy 19/ISO 9453) for attachment Additionally, when tinning fine-pitch leaded devices, the copper content must not exceed 0.300%.
Lead preparation
General
The detailed requirements for lead forming and preparation are described in the following subclauses.
Lead forming
The lead forming process must preserve the integrity of internal connections within components It is essential to adhere to the manufacturer's specified lead forming methods Furthermore, the component bodies, leads, and lead seals should remain intact and meet the fundamental specifications required for the components.
Lead forming limits
Components should not be mounted if their leads exhibit unwanted nicks or if there is a deformation in diameter or width that exceeds 10% This applies regardless of whether the leads are formed manually or by machine.
Exposed core metal is permissible as long as it does not exceed 5% of the solderable surface area of the lead Additionally, the presence of exposed base metal in the formed area of the lead should be regarded as a process indicator.
Overview
This article outlines the requirements for mounting terminals, mechanical and electronic components, and wires onto printed boards or other packaging and interconnecting structures In assemblies that utilize mixed component mounting technology, through-hole components should be positioned on one side of the printed board, while surface-mounted components can be placed on either or both sides of the assembly.
When design limitations require the use of components that cannot endure the soldering temperatures of a specific process, these components must be mounted and soldered separately In an assembly sequence where some components are soldered before others, it is essential to properly clean any flux residues If necessary, assemblies should be cleaned after each soldering operation to prevent contamination from affecting subsequent mounting and soldering processes.
Cleanliness
Maintaining the cleanliness of terminals, component leads, conductors, and printed wiring surfaces is essential for ensuring proper solderability and compatibility with future processes It is crucial that the cleaning process does not cause any damage to the components, their leads, conductors, or markings.
Part markings and reference designations
Part markings and reference designations shall be legible and components shall be mounted in such a manner that markings are visible.
Solder connection contours
Designs incorporating special solder connection contours for compensating coefficient of thermal expansion (CTE) mismatches must be clearly indicated on the approved assembly drawing Additionally, the mounting technique should effectively support a solder connection that complies with the specifications outlined in section 10.3.
Moisture traps
Within the constraints imposed by component and part design, parts and components shall be mounted to preclude the formation of moisture traps.
Thermal dissipation
When heat dissipation is required by the assembly, the material compatibility requirements of Clause 5 shall be followed
General
The detailed requirements for manual and machine soldering processes are defined in the following subclauses.
General
Soldering process
Soldering processes, as specified herein, shall not result in damage to the components or assemblies.
Machine maintenance
Machines used in the soldering process shall be maintained to assure capability and efficiency commensurate with design parameters established by the original equipment manufacturer
Maintenance procedures and schedules shall be documented in order to provide reproducible processing.
Handling of parts
To prevent damage to terminations and eliminate the need for lead straightening, parts must be handled carefully Once mounted on printed boards, assemblies should be transported and processed in a way that prevents movement, ensuring the formation of quality solder connections After soldering, it is crucial to allow the assembly to cool sufficiently so that the solder solidifies before any further handling, thereby avoiding hot cracking of the solder.
Preheating
Preheating assemblies is essential to minimize volatile solvents before soldering, as it helps reduce temperature differences across the board, mitigates thermal shock to components, enhances solder flow, and decreases the dwell time of molten solder It is crucial that the preheat temperature does not compromise the integrity of printed boards, components, or the overall soldering performance.
Carriers
Carriers for transporting printed circuit boards on the assembly line must be made from materials and designed in a way that prevents any impairment of solderability, degradation of boards, parts, or components, and protects against electrostatic damage (ESD) to components.
Hold down of surface mount leads
Short, stiff, or thick surface-mounted device leads should not be subjected to stress, such as from probes, during solder solidification to maintain reliability The resistance reflow system must ensure that lead deflection does not exceed twice the lead thickness, particularly for short or thick leads, where deflection should remain below this threshold.
Heat application
The elements to be soldered shall be sufficiently heated to cause complete melting of the solder and wetting of the surface being soldered.
Cooling
The connection shall not be subjected to detrimental movement or detrimental stress at any time during the solidification of the solder Controlled cooling may be used with documented processes.
Reflow soldering
Requirements
Reflow soldering operations require specific methods such as infrared, vapour phase, convection, laser, thermode, or conduction to effectively attach surface mounted devices These methods must ensure controlled pre-heating of printed wiring assemblies, maintain soldering temperatures within ±5 °C of the desired profile for various component sizes, and rapidly heat and cool the surfaces while adhering to thermal shock limitations Additionally, it is essential to minimize the impact of shadowing and color on the heating rates of individual components.
Process development for reflow soldering
Manufacturers must establish a consistent reflow soldering process within defined limits for the equipment, accompanied by detailed process instructions The reflow soldering operations should adhere to these instructions, ensuring a reproducible time/temperature envelope that includes necessary steps such as drying/degassing, preheating, solder reflow, and cooling These operations can be integrated into a single system or performed separately Any adjustments to the temperature/time profile for different printed wiring assemblies or variations must be documented.
Flux application
Flux must be applied before creating the final solder connection and can be part of solder paste or preform solder Any flux that meets the specifications of 5.3 is acceptable, as long as it does not harm the components and the cleaning processes, if necessary, ensure compliance with the cleanliness standards outlined in Clause 9 without negatively affecting the product.
Solder application
Enough solder shall be applied to components or boards or both to ensure that sufficient quantity is in place during reflow to meet the end point workmanship requirements
Effective methods for applying solder paste to surface mount land patterns include screen printing, stencil printing, dispensing, and pin transfer It is essential to follow the material supplier's recommendations for handling solder paste to ensure optimal performance To maintain quality, avoid reusing or mixing solder paste that has been exposed for extended periods (ranging from 1 to 24 hours) with fresh paste.
Surface mount land patterns can be coated with a defined amount of solder during the printed board manufacturing process
Various solder application methods are acceptable, including: a) SnPb plating, which is not suitable for lead-free soldering; b) screen or stencil printing of solder paste, which can be followed by a reflow solder process, with or without flattening the reflowed solder pads; c) the application of molten solder; and d) the use of solder particles combined with an adherent flux, known as solid solder deposit technology.
The solid solder deposit on land patterns exhibits several key characteristics: it forms a plated or molten intermetallic bond with the surface mounting device (SMD) land pattern, ensuring a reliable reflow solder joint due to adequate thickness Additionally, the solder must be applied with precision to the SMD land pattern, and the flatness of the deposited solder should meet the requirements of the specific component, as fine pitch devices necessitate greater flatness compared to other components.
The amount of the solder shall be specified.
Mechanized immersion soldering (non-reflow)
General
The requirements for immersion non-reflow machine soldering include the ability to apply flux to all necessary points, controlled pre-heating of printed board assemblies, and maintaining the soldering temperature within ±5 °C during production Additionally, the system must heat and cool the surfaces to be joined in a controlled manner while adhering to thermal shock limitations It should also provide sufficient mechanical energy to reduce shadowing effects and enhance wetting in tight spaces between closely packed surface mount components.
Process development for mechanized immersion soldering
The manufacturer must establish and maintain detailed operating procedures for the soldering process and the operation of the automatic soldering machine and its related equipment These procedures should specify essential parameters, including preheat temperature, solder temperature, travel rate, and the frequency of temperature verification measurements Additionally, they must outline the frequency and method for flux analysis, particularly for low-solids fluxes, as well as the solder bath analysis frequency Any adjustments made to these parameters for different printed wiring assemblies or identification elements must be clearly documented.
Drying/degassing
Prior to soldering, the assembly may be baked to reduce detrimental moisture and other volatiles.
Holding fixtures and materials
Devices, materials, and techniques employed to secure components to printed circuit boards during preheating, fluxing, soldering, and cooling must ensure that there is no contamination, damage, or degradation of the boards or components These methods should effectively maintain the positioning of components while allowing for proper solder flow through plated through-holes and onto terminal areas.
Flux application
The flux applied must create a protective coating on the soldering surface without compromising the reliability of the components It is essential to use thinning materials recommended by the flux supplier to ensure proper application Additionally, the flux should be adequately dried before soldering to avoid solder spatter.
Solder bath
To ensure optimal performance, the solder bath must be maintained at the temperature recommended by the solder supplier, without exceeding the heat resistance of the mounted components Different alloys may necessitate varying temperature ranges, but all should adhere to a nominal temperature tolerance of ±5 °C, ensuring that the bath temperature remains within the specified limits.
The temperature and contact time between the assembly and solder depend on factors like preheating, board thickness, and the size and number of contacts It's crucial to limit the exposure time of printed boards to the solder bath to prevent damage to the board and its components.
To ensure solder bath purity in machine soldering of printed board assemblies, it is essential to follow specific procedures Dross must be removed from the solder bath without coming into contact with the items being soldered, utilizing either automatic or manual methods Soldering oils can be mixed with molten solder and applied to the surface of the solder wave or bath, but the oil level must be managed to prevent contamination of solidified solder joints Additionally, regular analysis of the solder in soldering machines is required to maintain quality.
Manual/hand soldering
Requirements
The detailed requirements for manual/hand soldering are defined in the following subclauses.
Non-reflow manual soldering
Before applying heat, liquid flux must be applied to the surfaces to be joined, while avoiding excess flux When using cored solder, it should be positioned to allow the flux to flow and cover the connection elements as the solder melts Additionally, any external liquid flux used with flux cored solders must be compatible.
For optimal heat transfer, a well-tinned tip should be used at the joint, with solder introduced at the junction of the tip and connection Solder must be applied directly to the joint rather than the soldering iron tip, ensuring that it is supplied to the surface of the joint that has been heated Care should be taken to prevent solder deposits on the component body, and the soldering iron tip should be quickly removed from the joint Solder should only be applied to one side of a plated through-hole, and the soldering tip's temperature must not exceed the specified working temperature Heat application should adhere to the defined temperature and time limits, and in some cases, preheating may be necessary to protect components during hand soldering.
When hand soldering near heat-sensitive devices, it is essential to use a heat sink between the soldering iron tip and the component body to limit heat transfer into the component.
Limited solder wicking during soldering of wire is permissible Solder wicking shall not extend to a portion of the wire which is required to remain flexible.
Reflow manual soldering
To ensure that the end product meets quality standards, it is essential to apply an adequate amount of solder to components or boards during the reflow process Solder can be applied using various methods, such as dispensing, pin transfer of solder paste, or utilizing solder wire and preforms Additionally, it is crucial that the land patterns receiving the solder are clean before the application of solder and subsequent reflow methods.
Manufacturers must create a consistent reflow soldering process that adheres to the specified limits for hand soldering reflow equipment, such as hot air, gas, or infrared It is essential to develop and maintain clear reflow process instructions, ensuring that all procedures are executed in accordance with these guidelines.
The process must encompass a reproducible time/temperature envelope, which includes the drying and degassing operations when necessary Reflow techniques can involve hot air or gas guns, soldering irons, hot bar (thermode) methods, or laser operations.
When conducting manual reflow soldering, it is essential to implement proper shielding to protect adjacent components from damage and prevent the reflowing of their solder joints.
General
When the post soldering cleanliness designator indicates cleaning option C-0 (no surface to be cleaned), the soldered assembly must comply with the visual inspection requirements outlined in section 9.5.2, with the exception that flux residue is allowed.
Cleaning of parts, subassemblies, and final assemblies is essential during and after processing to ensure the effective removal of contaminants, particularly flux residue This cleaning must be conducted within a timeframe that allows for thorough contamination removal.
All cleaned items must be treated to avoid harmful thermal shock and prevent cleaning media from entering unsealed components The cleaning process for assemblies must adhere to the specified cleanliness standards.
Equipment and material compatibility
When selecting cleaning media and equipment, it is essential to ensure they effectively remove both ionic and non-ionic contaminants without causing any degradation to the materials, markings, or parts being cleaned Additionally, analysis and documentation proving adherence to these standards must be readily available for review.
Pre-soldering cleaning
To ensure solderability, terminals, component leads, conductors, and printed wiring surfaces must be adequately clean without compromising the reliability of the components Cleaning processes should not damage these elements, and for post-soldering option C-0, where no surfaces are cleaned, cleanliness must still meet the final assembly requirements.
Post-soldering cleaning
General
To ensure effective cleaning, flux residue should be removed promptly, ideally within 15 minutes and no later than 1 hour after soldering Certain fluxes may necessitate immediate cleaning for optimal removal Various mechanical methods, including agitation, spraying, and brushing, as well as vapor degreasing, can be employed alongside the cleaning medium For hand soldering operations, the time allowed for cleaning can be extended, provided that interim cleaning is conducted and thorough cleaning is completed before the end of the production shift.
Terminations internal to self-sealing devices (e.g heat shrinkable solder devices) shall be exempt from the cleaning requirements of this standard when the device encapsulates the solder connection.
Ultrasonic cleaning
Ultrasonic cleaning is allowed for bare boards or assemblies if they only contain terminals or connectors without internal electronics Additionally, it can be used on electronic assemblies with electrical components, provided that the contractor has documentation demonstrating that ultrasonic cleaning does not harm the mechanical or electrical performance of the product or its components.
Cleanliness verification
General
Assemblies must adhere to the cleanliness standards outlined in section 9.6 To evaluate the presence of residual particulates, foreign matter, flux residues, and other ionic organic contaminants, specific assessment methods will be employed.
Visual inspection
Visual inspection should be conducted as part of a documented process control and product improvement system, utilizing a statistical sample as outlined in section 13.2.3 In cases where this is not applicable, a 100% visual inspection is necessary to identify foreign particulate matter as specified in section 9.6.2, as well as flux and other ionic or inorganic residues as detailed in section 9.6.3.
Testing
Regular cleanliness testing of the assembly following final cleaning—such as before conformal coating, encapsulation, or integration into a higher assembly—must be performed on a random sample basis to verify the effectiveness of the cleaning processes, as stipulated in section 9.6.5.
In the event of an assembly failure, the entire lot must be recleaned, and a random sample from this lot, along with each lot cleaned since the last successful cleanliness test, will undergo testing Testing frequency is set at a minimum of once every 8-hour shift, unless supported by process control system data for a frequency adjustment.
Cleanliness criteria
General
Cleaning of assemblies shall be performed as necessary to remove a) particulate foreign matter as required in 9.6.2, and b) flux residues and other ionic or organic contaminants as required in 9.6.3.
Particulate matter
Assemblies must be clean and free from contaminants such as dirt, lint, solder splash, and dross Solder balls should remain secure and not compromise electrical performance Inspection for particulate matter must adhere to the methodology outlined in section 13.2.2.2.
Solder balls must not decrease the minimum design electrical spacing by over 50% and should be securely attached to the board surface Furthermore, the maximum allowable number of solder balls is five per 600 mm².
Flux residues and other ionic or organic contaminants
The user and manufacturer shall agree to the cleaning requirements and the appropriate tests for cleanliness In addition, the visual requirements for cleanliness shall be agreed to and specified
Users are responsible for defining cleanliness standards by selecting a cleanliness designator that outlines the cleaning options and testing methods as per section 9.6.3.2 If no cleanliness designator is specified, the default designator C-22 will be applicable, as detailed in the subsequent subclauses Furthermore, the visual cleanliness requirements must be clearly defined in accordance with section 9.6.3.3.
Where the user specifies a cleanliness designator, it shall be in the following form:
Cleanliness designator Cleaning option Test for cleanliness
The cleanliness requirements for all assemblies under this standard are indicated by a two-digit code that starts with the letter C, followed by a dash and two or more digits The first digit signifies the cleaning option outlined in section 9.6.4, while the subsequent digits specify the cleanliness testing requirements detailed in section 9.6.5 If all five cleanliness tests are mandated, the cleanliness designator will consist of a total of six digits.
Surfaces cleaned should be inspected without magnification and shall be free of visual evidence of flux residue or other contaminants Surfaces not cleaned may have evidence of flux residues.
Cleaning option
The initial digit of the cleanliness designator indicates the specific cleaning option, with each digit representing the surfaces of the assembly that require cleaning.
0 = No surfaces to be cleaned
1 = One side (wave solder source side) of assembly to be cleaned
2 = Both sides of assembly to be cleaned.
Test for cleanliness
The second and following digits of the cleanliness designator define the requirements for cleanliness testing The following digits may be used in any combination (not including zero):
0 = No test for cleanliness required
1 = Test for rosin residues required (see 9.6.6)
2 = Test for ionic residues required (see 9.6.7and/or 9.6.8)
3 = Test for surface insulation resistance (see 9.6.9)
4 = Test for other surface organic contaminants (see 9.6.10)
5 = Other tests as deemed by user/manufacturer agreement.
Rosin residues on cleaned board assemblies
If rosin-based fluxes are used, assemblies shall be cleaned and tested in accordance with the following
Cleaned assemblies must be tested according to IEC 61189-1 and IEC 61189-3, as outlined in Annex B, and must meet the specified maximum allowable levels of rosin flux residues.
Level A: assemblies less than 200 àg /cm 2
Level B: assemblies less than 100 àg /cm 2
Level C: assemblies less than 40 àg /cm 2
Ionic residues (instrument method)
Assemblies must be tested according to IEC 61189-1 and IEC 61189-3 standards, utilizing either dynamic or static methods for the ionizable detection of surface contaminants, as detailed in Annex B The acceptable limit for ionic or ionizable flux residue is less than 1.56 µg/cm² NaCl equivalent Alternative methods may be employed if they demonstrate equal or superior sensitivity in detecting ionizable surface contamination.
When comparing the sensitivity of different methods, it is essential to consider the solvent used for residue extraction, the technique employed to introduce the solvent to the assembly, and the detection method for the residue.
Ionic residues (manual method)
Assemblies must be tested according to IEC 61189-1 and IEC 61189-3 standards, specifically regarding the resistivity of solvent extract as outlined in Annex B The acceptable level of surface contamination is less than 1.56 µg/cm² of sodium chloride (NaCl) equivalent ionic or ionizable flux residue, although users may specify different acceptance values for equivalent tests.
Surface insulation resistance (SIR)
Test specimens that are processed identically to the assemblies being produced must undergo testing to evaluate the impact of contamination on the electrical insulation resistance of printed boards under high temperature and humidity, following the guidelines of IEC 61189-1 and IEC 61189-3 These tests should be conducted under the specified conditions of IEC 61189-1, ensuring that the specimens achieve a minimum resistance of 100 MΩ after soldering and/or post-soldering cleaning, based on the flux classification Additionally, the user and manufacturer can mutually agree on alternative test specimens, conditions, and SIR requirements.
Other contamination
Assemblies evaluated under IEC 61189-1 and IEC 61189-3 standards must adhere to the maximum acceptance levels for organic contaminant detection, as mutually agreed upon by the user and manufacturer.
General
The boards, components, and processes outlined in Clauses 1 to 8 ensure soldered interconnections that surpass the minimum acceptance standards It is essential that the processes and their controls are designed to produce products that meet or exceed the acceptance criteria for a level C product Nonetheless, all soldered connections must comply with the acceptance requirements for the specified product level (A, B, or C) as determined by the user.
Acceptance requirements
Process control
The manufacturer must implement either a process control plan as outlined in section 13.3 or conduct a 100% inspection per the requirements of section 10.3 If defects and process indicators surpass the corrective action limits defined in section 10.2.2 for their respective opportunity levels (10.2.3), the manufacturer is required to take corrective action to minimize their occurrence For the purpose of corrective action calculations, only one defect characteristic or process indicator may be assigned to a specific interconnection site, such as lead-to-land, via, or lead-in-hole.
Meeting the specified limits in this standard significantly enhances the likelihood that the joint will fulfill assembly expectations Nevertheless, it is the user's responsibility to accurately assess the true reliability requirements based on the design and intended use of the final product.
Corrective action limits
Corrective action will be triggered if defects exceed 0.3% of potential occurrences and if process indicators surpass 3.0% of total opportunities Additionally, it is essential to monitor the following general process indicator occurrences.
5) other process indicators defined in the sectional specifications; and
Control limit determination
The total number of interconnection sites serves as the basis for calculating the percentage of defects or process indicators This assessment includes each surface mount termination, through-hole termination, and terminal termination, treating each as a distinct opportunity for evaluating the overall number of opportunities in a printed board assembly.
General assembly requirements
Assembly integrity
All products must comply with the specifications outlined in the assembly drawing It is essential that the electrical and mechanical integrity, as well as the reliability of all components and assemblies, are maintained throughout the manufacturing and assembly processes, including handling, fixing, soldering, and cleaning.
Assembly damage
Assembly damage to electronic and mechanical devices shall not exceed the requirements given in the present standard and in IEC 61191-2, IEC 61191-3, IEC 61191-4
Printed boards shall show no evidence of burning, blistering, or delamination as referenced in IEC 62326-1 Laminate scratches shall be treated as weave exposure
The following defects can be found in printed wiring assemblies: measles, crazing, blistering, delamination, weave exposure, haloing, edge delamination, and lifted lands or conductors
Assemblies may be rejected for several reasons, including the presence of measling or crazing defects that impair functionality Additionally, blistering or delamination that creates bridges between plated through-holes or subsurface conductors, or that extends beneath surface conductors, can also lead to rejection.
Markings
Manufacturers must not intentionally change, erase, or remove markings unless specified by the assembly drawing Any additional markings, like labels added during manufacturing, should not cover the original supplier's markings If a component part loses its marking, this must be documented as a process indicator to identify potential marking issues with the supplier and assess the necessary corrective actions, such as using new materials, implementing new processes, or remarking.
Flatness (bow and twist)
The allowable bow and twist after soldering for printed board applications varies by surface mount level: it should not exceed 0.5% or 1.5 mm for level C, 0.75% or 2.0 mm for level B, and 1.0% or 2.5 mm for level A For through-hole assemblies, the limit is 1.5% or 2.5 mm across all levels Additionally, mixed assemblies, including both surface mount technology (SMT) and through-hole technology (THT), must comply with the requirements set for surface mount assemblies as outlined in IEC 61191-2, IEC 61189-3, and IEC 61188-1-1.
Solder connection
An acceptable solder connection demonstrates proper wetting and adherence, characterized by the solder merging with the surface at a contact angle of 90° or less, unless the solder quantity creates a contour that overhangs the edge of the land (refer to Figure 1) Additionally, solder joints should exhibit a smooth overall appearance.
A lead-free solder alloy composition will typically produce an appearance of surface roughness (grainy or dull) and greater wetting contact angles These solder joints are acceptable
A clear transition from the land to the connection surface or component lead is essential, with an acceptable demarcation zone where the applied solder merges with the solder coating or other surface materials, as long as wetting is visible For fused solder coatings, it is not necessary for the applied solder to extend above the rim of the hole if both the hole wall and component lead show good wetting Additionally, any marks or scratches on the solder joint should not compromise the integrity of the connection.
Non-wetting/dewetting evident (1e) IEC 1238/13
Figure 1 – Solder contact angle 10.3.5.2 Defects
Unacceptable conditions that are classified as defects include: fractured or disturbed solder connections, cold solder connections, and instances where more than 5% of solder connections (excluding vias) show dewet or nonwet characteristics Additionally, excess solder that contacts the component body, gold embrittlement resulting from inadequate gold removal, and voiding that reduces the solder volume of the joint below the permissible minimum value are also considered defects.
Acceptable conditions that serve as process indicators must be documented and available for review These include: a) voids and blow holes with visible wetting that do not decrease solder volume below the minimum allowable level; and b) instances where the outline or lead is obscured in the solder joint due to excess solder.
Acceptable holes – the coated or applied solder has wetted sides of holes (2a to 2f)
Figure 2 – Solder wetting of plated through-holes without leads
Interfacial connections
Unsupported holes with leads or plated through-holes used for interfacial connections and not subjected to mass soldering do not require solder filling Similarly, plated through-holes that are not exposed to solder due to maskants also do not need solder filling Plated through-holes without leads, including vias, must meet acceptability requirements after solder processing, as outlined in Figure 2; failure to do so will be considered a process indicator per Clause 13 While wetting of the top-side lands by solder is acceptable, it is not mandatory Additionally, any damage to plated through-holes caused by copper dissolution is classified as a defect, as detailed in Table 2.
Detail requirements
The detail requirements for coating and encapsulation procedures are defined in the following subclauses.
Conformal coating
Coating instructions
It is essential to adhere to the material specifications and supplier instructions Any deviations in curing conditions, such as temperature, time, or IR intensity, must be documented for review Additionally, materials should be utilized within the specified time frames for both shelf life and pot life, or according to a documented system established by the manufacturer to manage age-dated materials.
Application
A continuous coating is required in all designated areas on the assembly drawing, with minimal coating fillets The conformal coating material must be free of aggressive solvents and should not compromise the reliability of components during application Any masking materials used must not harm the printed boards and should be easily removable without leaving residue Additionally, the dimensions of masked areas should not be reduced by more than 0.8 mm in length, width, or diameter due to the application of the conformal coating.
The adjustable parts of components, along with electrical and mechanical mating surfaces like probe points, screw threads, and bearing surfaces (such as card guides), must remain uncoated as indicated in the assembly drawing.
Mating connector surfaces on printed wiring assemblies must remain free of conformal coating The conformal coating indicated on the assembly drawing should create a seal around the edges of all connector and board interface areas However, press-fit pins and connectors that are installed after the conformal coating has been applied are not subject to this sealing requirement.
Brackets and mounting devices should not have their mating surfaces coated with conformal coating unless specified in the assembly drawing However, the junction perimeter between these devices and the board, along with all attaching hardware, must be coated.
11.2.2.5 Conformal coating on flexible leads
Components which are electrically connected to the assembly by flexible leads (e.g gull wing) shall as a minimum have the junction of the leads with the components and the assembly coated
Unless stated otherwise in the approved assembly drawing, the total thickness of assemblies should not exceed an increase of 1.0 mm due to conformal coating The outer perimeter is defined as the region on each side of the board, extending no more than 6.0 mm inward from the outer edge (refer to Figure 3).
Not increased by more than 1,0 mm in area ″A″
The dimensions of the assemblies must not exceed an increase of 0.8 mm on each edge, totaling a maximum of 1.5 mm when applying conformal coating, unless otherwise indicated on the approved assembly drawing.
Performance requirements
The detailed requirements for applied coatings are defined in the following subclauses
The specified thickness for conformal coatings varies by type: for epoxy (ER), urethane (UR), and acrylic (AR) coatings, the thickness ranges from 0.03 mm to 0.13 mm; for silicone (SR) coatings, it ranges from 0.05 mm to 0.21 mm; for paraxylene (XY) coatings, the thickness is between 0.01 mm and 0.05 mm; and for fluoropolymer (FC) coatings, it is approximately 0.01 mm.
The thickness of the coating must be measured on a flat, unobstructed, cured surface of the printed wiring assembly or on a processed coupon These coupons can be made from the same material as the printed board or from non-porous materials like metal or glass Alternatively, a wet film thickness measurement can be utilized to determine the coating thickness, provided there is proper documentation linking the wet and dry film thicknesses.
The conformal coating must adhere to the specifications outlined in the assembly drawing, ensuring it is fully cured and homogeneous It should only cover designated areas, remain free of blisters or breaks that could impact assembly operations or sealing properties, and avoid voids, bubbles, or foreign materials that expose conductors or violate electrical spacing Additionally, the coating must not exhibit measling, peeling, or wrinkles, ensuring all areas are properly adhered.
Rework of conformal coating
Procedures which describe the removal and replacement of conformal coating shall be documented and available for review.
Conformal coating inspection
Visual inspection of conformal coating can be conducted without magnification, but using ultraviolet (UV) light can enhance the assessment of coverage when a UV tracer is present in the coating material For more detailed examination, magnification levels between 2× and 4× may be utilized for reference purposes.
Encapsulation
Encapsulation instructions
Material specifications and supplier instructions must be adhered to The material should be utilized within the specified time frame, considering both shelf life and pot life, or according to a documented system established by the manufacturer for marking and controlling age-dated materials.
Application
Encapsulant materials must be applied continuously in all specified areas on the assembly drawing Additionally, any masking materials used should not harm the printed boards and must be easily removable without leaving any residue.
All portions of the assembly not designated to receive encapsulant material shall be free of any encapsulant material.
Performance requirements
The applied encapsulant shall be completely cured, homogeneous, and cover only those areas specified on the assembly drawing
The encapsulant must be devoid of bubbles, blisters, or breaks that could impair the operation of the printed wiring assembly or compromise the sealing properties of the material Additionally, it should not exhibit any visible cracks, crazes, mealing, peeling, or wrinkles.
Rework of encapsulant material
Procedures which describe the removal and replacement of encapsulant material shall be documented and available for review (i.e., within the manufacturers' ISO 9001 documentation or equivalent written procedures).
Encapsulant inspection
Visual inspection of encapsulation may be performed with magnification
General
The detailed requirements for rework and repair are defined in the following subclauses.
Rework of unsatisfactory soldered electrical and electronic assemblies
Reworking unsatisfactory electrical and electronic assemblies involves correcting the defects outlined in Table 2, as well as addressing the non-conforming characteristics specified in the relevant sectional specifications, including IEC 61191-2, IEC 61191-3, and IEC 61191-4.
Rework of unsatisfactory solder connections and defects must be preceded by thorough documentation of discrepancies, as outlined in the process control plan, which may involve sampling or auditing This documentation is essential for identifying potential causes and determining the need for corrective actions as specified in sections 10.2, 10.2.2, and 10.2.3 Upon completion of rework, each reworked or reflowed connection must be inspected according to the standards set forth in section 10.3.5 and in compliance with section 13.2.
Table 2 – Electrical and electronic assembly defects
No Defect description Requirement subclause Remarks
01 Violations of the assembly drawing requirements a) missing component b) wrong component c) reversed component
02 Damage to components beyond procurement specification or the relevant sectional specification allowance a) component damage (cracks) b) moisture cracking (pop-corning)
03 Damage to the assembly or printed board a) measling or crazing that affects functionality b) blisters/delamination that bridges between PTHs/conductors c) excessive departure from flatness
04 Plated-through hole interconnections with and without leads a) non wetted hole or lead b) unsatisfactory hole fill c) fractured solder joint d) cold or disturbed solder connection
05 Violation of minimum design electrical spacing a) conductive part body or wire movement/misalignment b) solder balling c) solder bridging d) solder spikes e) solder webs/skins
Improper solder connections can lead to various issues, including dewetting or non-wetting, solder leaching, and insufficient solder application Other common problems are solder wicking, insufficient reflow, and incomplete joints that result in open circuits Additionally, excessive solder and solder voids can compromise connection integrity, while adhesive encroachment and gold embrittlement further exacerbate these issues.
07 Damaged marking on the board a) altered marking b) obliterated marking
08 Failure to comply with stated cleaning or cleanliness testing 9.6
09 Failure to comply with conformal coating requirements 11.2.3.3
Repair
Repairs involve modifications to an unsatisfactory final product to ensure it meets the original functional specifications The method of repair will be established through mutual agreement between the manufacturer and the user.
Post rework/repair cleaning
After rework or repair, assemblies shall be cleaned as necessary by a process meeting the requirements of 9.6
System requirements
General requirements for the establishment and maintenance of an effective quality assurance programme incorporating process control systems (see 4.5) are given in the following subclauses.
Inspection methodology
Verification inspection
Verification inspection includes monitoring operations to ensure that practices, methods, procedures, and a documented inspection plan are effectively implemented, as well as conducting inspections to assess product quality.
Visual inspection
Inspection before soldering, such as between component placement and soldering or during other process steps like solder paste application, should be conducted on a sampling basis to identify the causes of solder joint defects Following the soldering process, the assembly must be assessed according to the established process control plan or through 100% visual inspection.
The tolerance for magnification aids is set at 15% of the chosen magnification power, allowing for a range of 30% centered around this value When inspecting items, the magnification aids and lighting must be appropriate for the size of the item being processed Specifically, the magnification for inspecting solder connections should be determined by the minimum width of the land for the device under inspection, and magnification aids should comply with the specifications outlined in Table 3.
Land widths and land diameters mm Inspection Referee
Referee conditions are applicable solely for verifying products that have been rejected during inspection magnification In cases where assemblies feature mixed land widths, the higher magnification can be utilized for the entire assembly.
13.2.2.3 Partially visible or hidden solder connections
Partially visible or hidden solder connections are permissible if certain conditions are satisfied: a) any visible part of the connection on either side of the PTH or SMD connection is acceptable; b) the design must not impede solder flow to any connection element on the primary side of the assembly; and c) process controls must be upheld to ensure consistent assembly techniques.
Sampling inspection
Sample-based inspection should be implemented when it is part of a documented process control system, as outlined in section 13.3, or when it is included in a user-approved product assurance program.
Process control
System details
Process control must be a documented and reviewable system that aligns with ISO 9001, IEC 61193-3, or an approved user system, aiming to minimize variation in processes, products, or services to meet or exceed customer expectations Essential components of the process control system include: a) providing training for personnel responsible for developing and implementing process control and statistical methods; b) maintaining quantitative methodologies and evidence to ensure process capability and control; c) establishing improvement strategies to set initial process control limits and reduce process indicator occurrences for continuous improvement; d) defining criteria for transitioning to sample-based inspection and reverting to higher inspection levels when control limits are exceeded; e) ensuring 100% inspection of entire lots when defects are found in samples; f) implementing a system for corrective actions in response to process indicators, out-of-control processes, and discrepancies; and g) creating a documented audit plan to monitor process characteristics and outputs regularly.
Objective evidence of process control can be represented through control charts and statistical process control techniques, utilizing data from various sources such as inspections, non-destructive evaluations, machine operations, and periodic testing of production samples For effective management of attribute data, it is crucial to understand and control the process parameters that affect the desired response, establishing controls accordingly Additionally, attribute data, typically measured in parts per million of nonconforming products, can be correlated with a process capability index (Cpk) derived from variable data.
Available resources (e.g ISO 9001, IEC 61193-1, etc.) should be used in establishing the process control plan and defining the characteristics and criteria.
Defect reduction
To enhance quality and minimize defects, continuous process improvement techniques must be employed If processes exceed defined control limits, immediate corrective actions are necessary to avert future issues Should these corrective measures prove ineffective within 30 days, the matter will be escalated to plant management for further resolution.
Variance reduction
To ensure compliance with this standard, all deviations must be minimized and eliminated whenever economically feasible through effective process corrective actions Neglecting to implement these actions or relying on ineffective solutions may result in the disapproval of the process and its related documentation.
Health and safety
The materials mentioned in this standard may pose hazards, necessitating a risk assessment before their use It is essential to follow all safety precautions detailed in the material's data Adequate ventilation must be ensured in areas where solder chemicals are utilized or fumes are produced To safeguard personnel, all areas, equipment, and procedures must comply with relevant occupational safety and health regulations.