46 I.3.2 Method for additional components mounted on component side of board.... 49 I.3.5 Method for additional components mounted on reverse side or on component side of board to lead
Terms from other standards
For the purpose of this Standard, the terms and definitions from ECSS-S-ST-00-01 apply.
Terms specific to the present standard
3.2.1 modification process of modifying an electronic circuit by means of the addition or removal of electrical parts or wiring
3.2.2 repair change of a component with all its associated connections, including the fixing down of a lifted pad or track or any similar procedure described in this Standard
NOTE 1 Changing of components for tuning, i.e de-soldering and changing component value is not considered a repair, rework or modification operation
NOTE 2 During tuning, solder jointing is achieved with a minimum of solder, just enough to ensure contact
3.2.3 rework process of reworking of a defective solder joint (without component changing) as a consequence of the repair or modification process or for restoring good workmanship of potentially defective solder joints
Abbreviated terms
For the purpose of this Standard, the abbreviated terms from ECSS-S-ST-00-01 and the following apply:
Basic requirements
Hazard, health and safety precautions
a The supplier shall define and implement procedures to control hazards to personnel, equipment or materials.
Materials
All repair materials and components of the final product must adhere to the specified standards Additionally, solders, flux, and cleaning solvents must comply with the requirements outlined in ECSS-Q-ST-70-08, specifically in clauses 6.1, 6.2, and 6.3.
Facilities
a All facilities and tools for repair and modification of printed circuit board assemblies for space use shall be in conformance with ECSS-Q-ST-70-08.
General
All processes outlined in clauses 4.2 to 4.19 must adhere to the ECSS-Q-ST-70 requirements Additionally, the supplier is required to conduct all soldering operations in accordance with clauses 7 to 11 of ECSS-Q-ST-70-08 or clauses 8 to 12 of ECSS-Q-ST-70-38.
Many accessories and work aids specified in this Standard are included in specialized equipment The supplier must follow the repair or modification procedures outlined in clauses 4.6 to 4.18.
The verification of supplier repair and modification processes for each device is outlined in clause 14.1 of ECSS-d Suppliers must obtain formal approval from the project PA/QA representative for repairs and modifications, following NCR and NRB procedures as per ECSS-Q-ST-10-09 Components undergoing failure analysis must be removed from assemblies and handled carefully to preserve their condition If the proposed repair method, tools, or procedures are not addressed by this Standard, the supplier must document the repair process in the relevant NCR and ensure compliance with ECSS-Q-ST-10-09.
Repairs
Repair criteria
The supplier will perform repairs solely to restore the functionality or performance of a printed circuit assembly that has been compromised during assembly or testing.
Number of repairs
The maximum number of repairs allowed for any printed circuit board assembly, which includes soldering or epoxy adhesives, is limited to six Additionally, for assemblies containing over 120 passive chip components, the total number of repairs must not exceed 5% of the passive chip components.
NOTE 1 Repairing of passive chip components is not considered as critical as other components of the PCB and hence the larger number of repairs allowed
NOTE 2 A repair of one component or connector can involve operations on one or more of its leads c Repairs involving soldering operations shall not exceed three to any one area of 25 cm 2 d Repairs involving epoxy adhesives shall not exceed four to any one area of 25 cm 2
Modifications
Modification criteria
Modifying a printed circuit assembly involves revising interconnecting features, which can include interrupting conductors, adding components, or making wire connections Each revision of connections to a single component or connector is considered one modification, and similarly, the addition of a single component also counts as one modification.
Number of modifications
a The total number of such modifications on any one printed circuit shall not exceed three to any one area of 25 cm 2
Rework
Rework criteria
a All aspects of the reworked solder joint shall conform to ECSS-ST-Q-70-38 or ECSS-ST-Q-70-08,
Number of reworks
a The total number of such reworks on any one joint shall not exceed three.
Other requirements
The supplier is required to replace malfunctioning or damaged components with new identical or equivalent parts, ensuring that components removed do not compromise the integrity of nearby components Only one de-soldering operation is permitted per printed circuit termination, excluding those for chip components, which are limited to three replacements at a single location For any repair or modification methods not specified in this Standard or exceeding the outlined criteria, the supplier must adhere to a defined procedure.
2 Involve final customer in NRB f The supplier shall not straighten warped boards, with or without components.
Removal of conformal coating
Requirements
a The supplier shall not use soldering irons for coating removal
High operating temperatures can lead to charring of coatings and potential delamination in the base laminate It is essential to ensure that no damage occurs to the printed wiring assembly by carefully cutting around the repair area When utilizing the thermal parting tip, precautions must be taken to prevent melting of adjacent solder joints and circuitry Additionally, the application time for solvents should be limited to a maximum of 15 minutes.
To minimize potential damage, it is crucial to limit the duration of solvent application, as solvents can cause expansion of the coating media and adversely affect coatings on electronic components, even in areas distant from the direct application of the solvent.
Procedure
a The supplier should use method A.3.1 for polyurethane- and silicone-type coatings b The supplier should use method A.3.2 for epoxy-type coatings.
Acceptance criteria
a The solder on the area to be repaired shall be accessible b None of the following shall occur:
1 melting of adjacent solder joints or circuitry;
2 blistering, measling or charring of coating;
3 blistering, delamination, measling or charring of laminated base material;
4 cuts, scratches or other damage to printed wiring.
Solder joint removal and unclinching
Procedure
a Depending on the kind of solder joint, the supplier should use one or more of the methods described in B.3.1, B.3.2, B.3.3, B.3.4 and B.3.5
To choose the right method, consult the method descriptions Before starting, the supplier must eliminate any conformal coating applied to the circuit, following the procedure outlined in Annex A.
Acceptance criteria
a There shall be no residual solder present on the treated solder joint b None of the following shall occur:
1 melting of adjacent solder joints or circuitry;
2 lifting of the solder joint or pad track;
3 delamination of the base laminate;
4 damage to printed wiring or solder joint or pad
NOTE Damages such as cuts, scratches.
Repair of damaged gold-plated areas
Requirements
The supplier is responsible for repairing scratches only when the conductor's current-carrying capacity is insufficient Additionally, boards with defective plating, except as specified in requirement 4.8.1a, will be rejected by the supplier.
NOTE Defect plating might be flaking or blistering.
Procedure
a The supplier should use method C.3.1 for removal of solder splatter on gold plating b For repair of insufficient or scratched gold plating the supplier should apply the following procedure:
1 remove gold plating before soldering in conformance with clauses 7.2.4 of ECSS-ST-Q-70-08;
Acceptance criteria
4.8.3.1 Removal of solder splatter on gold plating a There shall be no residual solder present on the gold plating or damage to the plating
NOTE Colour changes on the conductor surface resulting from gold-tin alloying are permitted
4.8.3.2 Repair of insufficient or scratched gold plating a After repair, the supplier shall inspect the soldered joints in conformance with the accept/reject criteria of clause 12 in ECSS-ST-Q-70-08
Regular inspection of the pad or track area is essential to confirm that there has been no lifting and that the base material remains undamaged.
Repair of damaged conductor tracks
Requirements
a The damage shall not involve a length of track in excess of five times the conductor width.
Procedure
For conductor tracks with a thickness greater than 30 µm, the choice of tinned copper or silver wire must adhere to the specifications outlined in Table 4-1 Additionally, the maximum diameter of the wire should not exceed two-thirds of the conductor's width.
Table 4-1: Wire diameters for given conductor widths
Conductor width (mm) Wire diameter (mm) minimum AWG
3,20 0,51 24 c The supplier should use method D.3 d The supplier should use alternative coatings in method D.3 only according to disposition by NRB.
Acceptance criteria
a After repair, the supplier shall inspect the soldered joints in conformance with the accept/reject criteria of clause 12 in ECSS-Q-ST-70-08
Inspecting the pad or track area is essential to confirm that there has been no lifting and that the base material remains undamaged.
Repair of lifted conductors
Requirements
The maximum length of the lifted conductor that can be repaired is limited to the smaller value between one-half of the distance between two terminal areas and 2 cm Additionally, the number of repairs allowed for each printed circuit board assembly must adhere to the specifications outlined in clause 4.2.2.
Procedure
Suppliers must choose between method E.3.1 or E.3.2 based on their applicability Prior to implementing either method, it is essential for suppliers to eliminate any components or solder that may hinder the repair of the damaged conductor, as outlined in clauses 4.7 and 4.15.
Acceptance criteria
The lifted conductor track must be securely attached to the base laminate using fully cured epoxy, ensuring that it does not cover areas designated for future soldering Additionally, when components are removed and replaced, the supplier is responsible for inspecting the soldered joints according to the accept/reject criteria outlined in clause 12 of ECSS-Q-ST-70-08.
Regular inspection of the pad or track area is essential to confirm that no lifting has occurred and that the base material remains undamaged.
Repair of lifted terminal areas (pads)
Requirements
Repairs must adhere to the specified circuitry spacing outlined in clause 17 of ECSS-Q-ST-70-10 In the unshaded regions of Figures F-2 and F-3, disbonded material should not exceed half the distance from the terminal area's edge to the nearest hole edge, covering no more than 180° of the periphery For plated through holes, upon completion of the repair, a clinched lead-through must be inserted by the supplier.
NOTE This can be a separate wire link or the component lead.
Procedure
a The supplier should use method F.3 b Before starting, the supplier shall remove components and solder that impinge on the repair area in conformance with the agreed methods.
Acceptance criteria
a The acceptance criteria shall be as stated in clause 4.10.3.
Terminal post replacement
Requirements
The supplier is permitted to replace terminal posts only if the process can be executed without causing damage to nearby conductor tracks, base laminates, or components Additionally, the supplier is prohibited from performing any straightening operations.
Procedure
a The supplier should use method G.3.
Acceptance criteria
The terminal installation must adhere to the manufacturer's procedures, ensuring that there is no visible damage to nearby conductor tracks, base laminate, or components Additionally, if any components are removed and replaced, the supplier is required to inspect the soldered joints according to the acceptance and rejection criteria outlined in clause 12 of ECSS-Q-ST-70-08.
Regular inspection of the pad or track area is essential to confirm that there has been no lifting and that the base material remains undamaged.
Wire-to-wire joints
Requirements
a The supplier shall undertake repairs only after NRB approval
When evaluating time, cost, and functionality, repair may prove to be more efficient than installing new components Additionally, if a wire is designed to bypass a component, it must be securely fixed at each bend It is also crucial for the supplier to prevent flux from entering between the conductor and the insulating sleeve during the repair process.
Procedure
a The supplier should use method H.3.
Acceptance criteria
a The supplier shall inspect the joint as per agreed method b No damage to adjacent conductor tracks, base laminate or components shall be visible.
Addition of components
Requirements
4.14.1.1 General a The supplier shall add components only if such addition does not invalidate the physical dimension requirements as specified in clause 17 of ECSS-Q-ST-70-10 b If the remaining portion of lead on the non-component side of the board is removed, the supplier shall also remove any clinched portion in conformance with clause 4.7
4.14.1.2 Extension of component leads a The supplier shall extend the leads for an equal distance on each side of the component by means of the lap joint method defined in Annex H or the wraparound method of clause “Turret and straight pin terminals” of ECSS-Q-ST-70-08 b The supplier shall cover the wires with space-approved insulation c The lead extension shall be such that it does avoid subsequent vibration problems by possible staking of the lead d The first spot bond of the extension wire shall not be more than 15 mm from the component-to-wire soldered joint.
Procedure
The supplier must utilize methods I.3.1, I.3.2, I.3.3, I.3.4, or I.3.5 for single-sided or double-sided boards For double-sided boards, the appropriate method (I.3.1 or I.3.2) should be selected based on the required configuration If packaging allows for components to be mounted on the underside without issues, methods I.3.1, I.3.4, and I.3.5 should be employed Method I.3.3 is applicable when there is adequate metallic land, as specified in clause 17 of ECSS-Q-ST-70-10, to facilitate both soldering and swaging of the terminal post, or for drilling the terminal post hole followed by soldering Additionally, method I.3.4 should be used for adding axially and non-axially leaded components and DIL packages.
Acceptance criteria
a After repair, the supplier shall inspect the soldered joints in conformance with the accept/reject criteria of clause 12 in ECSS-Q-ST-70-08
Regular inspection of the pad or track area is essential to confirm that there has been no lifting and that the base material remains undamaged.
Removal and replacement of axial and multi-lead components
Requirements
a If the portion of lead on the non-component side of the board is removed, the supplier shall also remove any clinched portion in conformance with clause 4.7
Exercise caution when handling circuit boards with plated through holes, as the connecting surfaces can easily rupture Additionally, very small lands pose a risk of loosening if the base material's temperature is too high or if excessive force is applied during lead removal.
Procedure
a The supplier should use method J.3.1 and J.3.2.
Acceptance criteria
a After repair, the supplier shall inspect the soldered joints in conformance with the accept/reject criteria of clause 12 in ECSS-Q-ST-70-08
Inspecting the pad or track area is essential to confirm that there has been no lifting and that the base material remains undamaged.
Removal and replacement of flat-pack components
Requirements
The supplier is responsible for the removal of larger flat-packs bonded to the PCB for mechanical or thermal support as part of a Non-Recurring Build (NRB) Additionally, it is essential to prevent scratching and overheating, with demonstrated preventive measures in place.
Procedure
a The supplier should use method K.3 b If another method is used, the supplier shall submit it for approval.
Acceptance criteria
a After repair, the supplier shall inspect the soldered joints in conformance with the accept/reject criteria of clause 12 of ECSS-Q-ST-70-08
Inspecting the pad or track area is essential to confirm that there has been no lifting and that the base material remains undamaged.
Modification of component connections
Requirements
a For modification of DIL package connections, the supplier shall not crop or insulate more than one third of the leads per side
In method L.3.3, guidelines for cropping leads are outlined, while method L.3.7 focuses on insulation It is important to note that a maximum of two leads can be cropped or insulated on each side of a 14-lead DIL package.
Procedure
Suppliers must utilize one of the specified methods, including I.3.6, I.3.7, L.3.1, L.3.2, L.3.3, L.3.4, L.3.5, L.3.6, L.3.7, or L.3.8 Specifically, method L.3.2 is recommended for mounting components with leads that have a larger diameter than the existing plated through holes on the printed circuit board Method L.3.3 should be employed only when cropping no more than one third of the leads on each side of a DIL package is necessary Additionally, method L.3.5 is applicable when the plated through hole is occupied by a flat-section lead Lastly, method L.3.7 is to be used when isolating a component lead from its plated through hole connection is required on double-sided or multi-layer printed circuit boards.
Although Figure L-1 depicts an isolated lead of a DIL package, this isolation method is also applicable for metal can packages Suppliers should employ method L.3.7 when isolating no more than one-third of the leads on each side of a DIL package Additionally, method I.3.7 should be used only when the glued surface on the PCB is not tinned.
Acceptance criteria
After modifications, including the removal and replacement of components, the supplier must inspect the soldered joints to ensure they meet the accept/reject criteria outlined in clause 12 of ECSS-Q-ST-70-08.
Inspecting the pad or track area is essential to confirm that there has been no lifting and that the base material remains undamaged.
Cutting of internal track of a multi-layer printed circuit board
Procedure
a The supplier should use method M.3 b If another method is used, the supplier shall submit it for approval.
Acceptance criteria
a The supplier shall inspect the re-worked area b There shall be no damage to adjacent conductor tracks, plated through holes, components and base laminate.
Quality assurance
General
Data
a The supplier shall retain the quality records (e.g logbooks) for at least ten years or in conformance with project business agreement requirements, b Quality records shall contain, as a minimum, the following:
1 copy of final inspection documentation;
2 index of limited-life articles and their use times;
3 nonconformance reports and corrective actions;
4 copy of the inspection and test results with reference to the relevant procedure.
Nonconformance
a Any nonconformance shall be handled in conformance with ECSS-Q-ST-10-09.
Calibration
a The supplier shall calibrate each reference standard and piece of measuring equipment b The supplier shall record any suspected or actual equipment failure as a project nonconformance report
The objective is to review previous results to determine the necessity of re-inspection or retesting Additionally, the supplier must inform the final customer about the specifics of any nonconformance.
Traceability
The supplier is responsible for ensuring traceability throughout the entire process, from incoming inspection to final testing, which includes documenting test equipment, serial numbers, and the personnel involved Additionally, any repairs, modifications, or rework performed on the printed circuit board assembly must be accurately recorded in the relevant documentation.
Operator and inspector training and certification
All operators and inspectors involved in repair or modification procedures must be trained and certified according to clause 14.8 of ECSS-Q-ST-70-08 Additionally, they are required to complete an advanced training program to ensure their proficiency in the specified repair methods.
Annex A (informative) Removal of conformal coating
Introduction
Before disassembling components from printed circuit assemblies, the operator must remove any conformal coating to ensure that the solder in the repair area is easily accessible and that the re-soldered joint remains uncontaminated.
Tools and materials
• thermal parting device complete with tips,
Methods for the removal of conformal coating
Method for the removal of polyurethane and silicone-type coating
To replace a component coated with silicone-type conformal coating, first, carefully cut through the coating using an appropriate cutting tool Next, peel back the cut section while using a vacuum cleaner to eliminate any loose particles Before removing the solder joints, clean the exposed area thoroughly with an approved solvent, as outlined in ECSS-Q-ST-70-08 clause 6.4, ensuring to use a minimal amount of solvent and preventing it from seeping under the edges of the conformal coating.
Method for the removal of epoxy-type coating
To effectively remove a component from a circuit board, first select a suitable thermal parting tip and set the nominal tip temperature according to the manufacturer's guidelines Apply the tip to the coating with light pressure, adjusting the temperature to break down the coating without causing scorching Gradually reduce the coating thickness around the component while avoiding contact with the board surface, and preclip the component leads for easier removal later Utilize a pencil-type vacuum cleaner and a bristle brush to clear waste material, ensuring good visibility and preventing damage to the board Once enough coating is removed, heat the component body to weaken the bond and lift it free from the board Finally, use additional thermal parting to eliminate any remaining coating and extract the leads and solder joints as outlined in Annex B.
Figure A-1: Removal of coating by thermal parting device
Annex B (informative) Solder joint removal and unclinching
Introduction
To effectively repair an electronic circuit, the first step is to remove the solder joint that holds the component in place There are several techniques available to accomplish this while minimizing the risk of thermal and mechanical damage during the replacement process The following sections outline various removal methods tailored to different facilities and specific conditions.
Tools and materials
• Soldering iron or hot jet blower (as applicable),
• solder sucker: continuous vacuum device, hand, wicking wire (as applicable), and
• thermal parting device, tweezers, pliers (as applicable).
Methods for solder joint removal and unclinching
Method for solder extraction with continuous vacuum
To achieve continuous vacuum during soldering, operators can utilize a vacuum pump or a dedicated vacuum device connected to the soldering iron The solder is extracted from the joint either directly through the iron's tip or via the attached vacuum device When the heated tip of the iron is applied to the soldered joint and the solder begins to melt, the vacuum is activated—often using a foot switch—allowing the solder to be drawn from the joint and collected in a designated chamber.
With appropriate handling, this method will minimise the overheating problem The correct positioning of the vacuum device tip is shown in Figure B-
Figure B-1: Continuous vacuum solder extraction on stud lead
Method for solder extraction using sucker
The solder removal method using a sucker tip involves applying vacuum in short pulses, which often necessitates multiple repetitions of the procedure This technique, which requires the simultaneous use of a soldering iron and a sucker tip, has limited applications due to its inherent disadvantages.
Figure B-2: Pulse-type solder sucker in use
Method for hot jet extraction
This technique utilizes a narrow jet of heated air, ranging from 200 °C to 300 °C, to effectively melt defective solder joints, making it ideal for flat package circuits The precision of the jet allows for the individual unsoldering of connecting wires without impacting adjacent joints After melting, the solder is either wicked off or vacuumed away, although this method is used only in specific situations.
Figure B-3: Lifting individual leads with hot jet
Method for the use of wicking braid
This method utilizes braiding saturated with flux or stranded wire heated in contact with the solder joint, allowing capillary action to draw molten solder into the wick It is effective for large surface joints and can be applied to through-hole solder joints, though it is more challenging for solder between a clinched lead and a terminal area However, as the amount of solder wicked out increases, capillary action diminishes, often necessitating repeated heat applications, which poses a risk of overheating.
Figure B-4: Cross-sectional view of wicking method
Method for unclinching of leads
To effectively remove solder from clinched leads, begin by using method B.3.1 (Vacuum) or method B.3.4 (Wicking) to eliminate surface solder around the lead and terminal area, allowing for a clear view of the clinched lead's contact with the terminal After the solder is removed, let the joint cool for a few seconds before gently lifting the wire with a thin plastic rod to avoid damaging the terminal; alternatively, tweezers or pliers can be used, ensuring they do not touch the terminal area Finally, once the clinched leads are straightened, proceed to remove the solder joints using method B.3.1, treating them as if they were unclinched leads.
Figure B-5: Hot unclinching with thermal parting device
Annex C (informative) Repair of damaged gold-plated areas
Introduction
Gold-plating can be damaged as a result of: a solder splatter on gold plating; b uneven scratched plating.
Tools and materials
• solder sucker, wicking wire, pencil-type vacuum cleaner,
• safety glasses (or similar protecting device),
Methods for the repair of damaged gold-plated areas
Method for the removal of solder splatter on gold plating
To effectively remove solder during the gold plating process, first vacuum or wick the solder using flux-impregnated wire, applying heat only until the solder melts Next, eliminate any remaining solder with a glass fiber eraser and a vacuum cleaner Finally, clean the repair area using an approved solvent.
Annex D (informative) Repair of damaged conductor tracks
Damage to the conductor can manifest as either a complete break or as scratches and nicks, which diminish its current-carrying capacity below standard requirements.
Tools and materials
Method for the repair of damaged conductor tracks
To repair a break in a conductor, first clean both sides of the break using a fiber eraser and an approved solvent, extending at least three times the track width on each side Next, cut a piece of tinned copper or silver wire that is at least six times the track width Position the wire on the center line of the conductor with tweezers and solder it in place After soldering, clean the area again with an approved solvent Finally, apply a small amount of epoxy resin over the entire repair and allow it to cure Alternative coatings may be used as specified by NRB.
Annex E (informative) Repair of lifted conductors
Introduction
This procedure is applicable where a portion of the conductor has lifted from the substrate but not broken (refer to Figure E-1)
Tools and materials
• space-approved epoxy adhesive (compatible with base epoxy),
• strip of thin PTFE sheet,
Methods for repair of lifted conductors
Method for the use of epoxy under conductor
To ensure proper adhesion of the lifted conductor, first clean the underside and surrounding area with an approved solvent, removing any particles that may hinder contact with the substrate Next, use a hot air lance to gently blow adhesive under the entire length of the lifted conductor, taking care to avoid contact with areas designated for soldering Press the conductor against the substrate using small weights, covering the interface with a thin piece of PTFE, and cure according to the manufacturer's data sheet Finally, refrain from handling the repaired units until the epoxy has fully cured.
Figure E-2: Repair using epoxy under conductor
Method for the use of epoxy over conductor
To repair a lifted conductor, first clean the upper face and surrounding area with an approved solvent Next, apply epoxy to the damaged surface and extend it at least 3 mm in all directions Ensure the epoxy cures according to the manufacturer's data sheet, and avoid handling the repaired units until the curing process is complete.
Figure E-3: Repair using epoxy over conductor
Annex F (informative) Repair of lifted terminal areas (pads)
Introduction
This procedure applies to terminal areas that are separated, loosened, or lifted from the base material, as illustrated in Figure F-1 It also includes terminal areas that have sustained damage from tearing, cutting, or other mechanical methods beyond established acceptance limits, as referenced in Figures F-2 and F-3 Additionally, it covers terminal areas specifically designed for clinched leads.
Figure F-2: Terminal areas without track
Figure F-3: Terminal areas with track attached
Tools and materials
• oven (if thermal curing epoxy is used),
• plastic or wooden toothpicks (for lifting terminal area whilst cleaning),
• space-approved epoxy resin compatible with base epoxy,
Method for the repair of lifted terminal areas (pads)
To ensure a successful repair, first clean all dirt, fingerprints, and foreign matter from the pad and surrounding area using isopropyl alcohol or an approved solvent Next, apply space-approved epoxy adhesive under the copper using a camel-hair brush, syringe, or suitable applicator Clean the solder side of the terminal area, then press it down with a clamp or weight unit Finally, allow the repair to air cure or bake according to the manufacturer's instructions before proceeding with any further work.
Annex G (informative) Terminal post replacement
Introduction
This procedure is applicable when terminal posts have become damaged.
Tools and materials
Method for the replacement of terminal post
To repair a damaged terminal post, first, remove the conformal coating around the affected area Cut the component leads to detach the component from the terminal post, and eliminate any remaining lead sections as per Annex J Support the printed circuit assembly on a jig to prevent flexing during drilling Use a drill bit approximately 80% of the post diameter to drill into the post, exceeding the epoxy board thickness Then, switch to a drill bit that matches the terminal post size and carefully drill until the swaged section is removed Remove any solder from the base of the post, and gently pull the post from the assembly using pliers, applying heat if necessary Clean the area with an approved solvent and pencil vacuum cleaner before fitting a replacement terminal post according to standard manufacturing procedures After cleaning with solvent, inspect the joint for proper swage and soldering, install the new component, and reapply the conformal coating Finally, ensure that internal layers are connected on PCBs with more than two layers and plated-through holes.
Introduction
Wire-to-wire joints are used for wires that are broken or require lengthening for modification purposes.
Tools and materials
• soldering iron, solder and flux,
• heating means (infrared or hot air),
• heat shrink sleeving (transparent, approved type),
• cotton gloves or finger cots.
Method for wire-to-wire joining
To ensure proper wire preparation and soldering, first, cut the wires to the correct length and remove insulation as specified in ECSS-Q-ST-70-08, ensuring compliance with insulation clearance requirements If the lay of a stranded conductor is disturbed, restore it without using bare fingers Pre-tin the wires according to clause 7 of ECSS-Q-ST-70-08, then place heat-shrink sleeving over the insulation for later use Position the wires in a joined configuration, securing them with a clamping device if necessary Solder the wires together to create a lap-type joint, maintaining a low contact angle and ensuring the contours of the individual conductors are visible Clean the joint area with an approved solvent to remove flux, and inspect the joint as per clause 12 of ECSS-Q-ST-70-08 Finally, position the shrink sleeve over the joint, shrink it according to the manufacturer's instructions, and ensure the shrink temperature remains below the solder's melting point For specific configurations, a wrap-around joint may be used for component lead extension Bond the extended wire to the board with a space-approved adhesive, ensuring the first spot bond is within 1.5 cm from the soldered joint and maintaining intervals of no more than 2.5 cm along its length.
Figure H-1: Use of approved type support clamp/heat sink
informative) Addition of components
Introduction
Additional components may be necessary in a printed circuit assembly due to design oversights, modifications identified during subsequent testing, or changes in design requirements.
Tools and materials
• approval solvent and cleaning brushes,
• approved epoxy paste staking compound,
• approved thixotropic polyurethane staking compound,
Methods for addition of components
I.3.1 Method for additional components mounted on reverse (non-component) side of board a Using lint-free paper, mask as much as possible of the circuitry surrounding the area to be worked b Carefully remove any conformal coating from the area to be worked Use the method described in Annex A c If the new component lead traverses conductors, assemble insulating sleeving to the section of lead that will not be soldered (refer to Figure I-
To properly form the component lead, ensure it aligns with the center-line of the conductor track, adhering to clause 8.1.5 of ECSS-Q-ST-70-08 The diameter of the component lead should not exceed two-thirds of the track width After soldering the component into position, remove the protective paper and clean the soldered area using an approved solvent Conduct an inspection in accordance with clause 8.1.5 of ECSS-Q-ST-70-08, and finally, re-apply the conformal coating, curing it as specified in the manufacturer's data sheet.
Figure I-1: Additional components mounted on reverse (non-component) side of board
I.3.2 Method for additional components mounted on component side of board a Using lint-free paper, mask as much as possible of the circuitry surrounding the area to be worked b Carefully remove any conformal coating from the area to be worked Use the method described in Annex A c Drill holes in the printed circuit assembly adjacent to the conductor tracks to which the component is to be joined Use the vacuum cleaner during this operation to remove swarf Drill holes with diameters which are of the size component lead diameter, plus 0,25 mm to 0,50 mm Position the hole that the edge of the hole is a minimum of 0,2 mm from the edge of the conductor d Form the component leads and assemble the component to the board as shown in Figure I-2 Components may also be mounted parallel with existing tracks to avoid additional bending of leads Consider the stress relief and bend radius requirements of clause 8.1.5 in ECSS-Q-ST-70-08 e Place the section of the component lead to be soldered along the centre line of the conductor and solder into this position (refer to Figure I-2) f Use component lead diameter (or width) less or equal to two thirds of track width g Clean soldered area with approved solvent h Inspect in conformance with clause 8.1.5 of ECSS-Q-ST-70-08 i Re-apply conformal coating and cure according to the manufacturer data sheet
Figure I-2: Additional components mounted on component side of board
I.3.3 Method for additional components mounted on terminal posts, including “piggyback“ mounting a Using lint-free paper, mask as much as possible of the circuitry surrounding the area to be worked b Carefully remove any conformal coating from the area to be worked Use the method described in Annex A c Drill the terminal post holes into suitable land areas of the conductor track Use the vacuum cleaner during this operation d Mount and solder the terminal posts in their respective holes e Solder the component to the terminal posts in conformance with clause 9 ECSS-Q-ST-70-08 f If it is necessary to attach the leads of the component to the non-component side of the board, use method I.3.2 step c
When mounting components on a PCB, ensure they are parallel with one side resting on the board "Piggyback" mounting, where one component is placed on top of another, is also allowed In this case, solder the upper component to the terminal posts as illustrated in Figure I-3 To secure the components, apply an approved staking compound to bond their bodies and attach the lower component to the board Finally, reapply conformal coating and cure it according to the manufacturer's specifications.
Epoxy staking compound Terminal post
Figure I-3:“Piggyback” mounting of one component on top of another
I.3.4 Method for additional components mounted (on reverse side or on component side of board) using staking compound
To prevent vibration issues, it is essential to bond components securely Various configurations are acceptable, as illustrated in Figures I-4 through I-7 Begin by masking the surrounding circuitry with lint-free paper Next, carefully remove any conformal coating from the work area using the method outlined in Annex A For the configuration in Figure I-7, drill holes in the double-sided printed circuit board at the designated mounting position, ensuring to use a vacuum cleaner to eliminate swarf The hole diameter should be the component lead diameter plus 0.25 mm to 0.50 mm, and this method can also be applied to multi-layer boards with precautions to avoid damaging internal conductors Finally, form the component leads and bond the component to the board using epoxy paste or thixotropic polyurethane staking compound, following the curing instructions provided in the manufacturer’s data sheet.
When a DIL package is mounted upside down, it is essential to de-gold and pre-tin the leads according to clause 7.2.3 of ECSS-Q-ST-70-08 Additionally, re-mark the part coding on the underside to maintain proper identification.
When addressing stress relief and bend radius requirements as outlined in clause 8.1.5 of ECSS-Q-ST-70-08, it is essential to use pre-tinned strips while employing a heat sink to prevent wicking Additionally, ensure that the insulated wire used for component lead extension is space-approved and properly formed.
To connect the top and bottom sides of double-sided or multi-layer printed circuit boards, insulated wire can be inserted through unused plated through holes without drilling or solder-wicking AWG 30, silver plated, stranded, insulated wire is suitable for a plated through hole with a diameter of 0.75 mm Solder wires to component leads using a wrap-around connection as specified in the ECSS-Q-ST-70-08 standard For certain components, a heat sink should be used to prevent the reflow of low melting point soldered connections Clean the soldered area with an approved solvent and inspect it according to clause 12 of ECSS-Q-ST-70-08 Position wire extensions on the board and bond them in accordance with Annex H, then re-apply conformal coating and cure it as per the manufacturer's data sheet.
I.3.5 Method for additional components mounted (on reverse side or on component side of board) to leads of adjacent components
To ensure proper assembly and maintenance of electronic components, follow the configurations outlined in Figures I-8, I-9, and I-10 Begin by masking the surrounding circuitry with lint-free paper and carefully remove any conformal coating from the work area as specified in Annex A For Figures I-8 and I-9, remove adjacent components and replace them with new ones featuring leads extended in the “Z” direction or a formed “pigtail” lead Form the leads while considering stress relief and bend radius requirements as per clause 8.1.5 of ECSS-Q-ST-70-08 In the case of Figure I-10, ensure insulating sleeving is assembled on leads that will not be soldered if they pass above a conductor Solder the leads using a wrap-around connection method as described in the “Turret and straight pin terminals” clause of ECSS-Q-ST-70-08, then clean the soldered area with an approved solvent Conduct an inspection in accordance with clause 12 of ECSS-Q-ST-70-08, bond components to the board for Figures I-9 and I-10, and finally, reapply conformal coating and cure it according to the manufacturer's data sheet.
Figure I-4: Mounting and wiring of additional axially-leaded components mounted (on reverse side or on component side of board) using staking compound
Figure I-5: Upside down mounting and wiring of additional side-brazed DIL component
(on reverse side or on component side of board) using staking compound
The mounting of additional non-axially leaded components, such as capacitors, involves connecting the top or bottom sides of the circuit board with wire This process utilizes a staking compound applied either on the reverse side or the component side of the board.
Plain holes drilled to take extended lead
Base laminate (Double-sided board)
Figure I-7: Mounting of additional component (on component side of board) with wire connections on reverse side of board using staking compound
Components replaced and leads extended
Figure I-8: Mounting of additional component (on reverse side of board) across extended leads of adjacent components
Component replaced and lead “pigtailed”
New component bonded to board
Figure I-9: Mounting of additional component by linking to a “pigtailed” lead of an adjacent component
Wrap-around connection to transistor lead, away from stress relief bend
(bonded to board and component)
Sleeved lead bonded to board (required when lead passes above a conductor)
New component bonded to board
Figure I-10: Mounting of additional component by linking to lead of an adjacent transistor
I.3.6 Method for the addition of a wire link onto soldered chips on a single side piece of PCB with appropriate pads
The number of pieces of PCB should not exceed two within any one area of
To properly attach a piece of PCB onto a tinned surface, ensure that the area does not exceed 50% of the piece's surface Begin by gluing the PCB with epoxy and allowing it to cure Next, solder wire onto the designated pads of the PCB, ensuring the length exceeds 1.2 mm Clean the soldered area with an approved solvent and inspect the joint according to clause 12 of ECSS-Q-ST-70-08 Position the extended wire on the board and bond it using a suitable space-approved adhesive, applying spot bonds along its length at intervals no greater than 3 cm, starting just after the wire stress relief Finally, re-apply conformal coating and cure it according to the manufacturer's data sheet.
I.3.7 Method for the addition of a wire link onto metallized cap of chips directly glued on PCB a Put an epoxy spot at the centre of component, suited with the size of package b Bond the chip on PCB and cure c Check that the epoxy spot does not extend onto metallized cap d Solder silver wires or insulated wire (refer to Figure I-11 e Clean soldered area with approved solvent f Inspect in conformance with clause 12 of ECSS-Q-ST-70-08 g Position the extended wire on the board and bond to the board by using a suitable space-approved adhesive (epoxy spot) Bond the lead along its length at intervals of not more than 3 cm, if it is longer than 3 cm Make the first spot bond of the extension wire just after the wire stress relief h Re-apply conformal coating and cure in conformance with the manufacturer data sheet
Figure I-11: Addition of a wire link onto metallized cap of chips directly glued on PCB
Annex J (informative) Removal and replacement of axial and multi-lead components
Introduction
This procedure is applicable to components having axial or multi-lead configurations.
Tools and materials
• Side-cutting pliers or diamond saw,
Methods for removal and replacement of axial and multi-lead components
J.3.1 Method for the removal of components with axial leads (destructive removal) a Cut the vertical section of the component leads just above the solder fillet and parallel to the surface of the board Ensure that burrs are not formed b Remove the remaining portion of the lead on the other side of the board using either a soldering iron with wick or vacuum extractor, then gently pull the lead with long-nose pliers when the solder is molten c Remove excess solder with a vacuum extractor or solder remover d Clean up the area of the joint with an approved solvent e Fit new component and solder it in place in conformance with clause 8 ECSS-Q-ST-70-08
J.3.2 Method for the removal of multi-lead components (destructive removal) a Cut component leads using diamond saw or side-cutting pliers (refer to Figure J-1 and Figure J-2) b Unsolder and remove the remaining portion of the leads on the other side of the board, whilst gently pulling with long-nose pliers when the solder is molten c Remove excess solder with a vacuum extractor or by the wicking method d Clean the area of the joint with an approved solvent e Fit new component and solder in place in conformance with clause 8 of ECSS-Q-ST-70-08
Figure J-1: Removal of multi-lead components, clipping of component leads
Figure J-2: Removal of multi-lead components, removal of remaining component leads
Annex K (informative) Removal and replacement of flat-pack components
Introduction
This procedure applies to flat-pack components installed on printed circuit boards, positioned in alignment with the conductive pattern through lap-soldered joints.
Tools and materials
• strip Kapton or Teflon sheet (approx 6 cm long),
• lead-bending fixture for flat-pack circuits, and
• approved solvent and cleaning tissue.
Method for the removal and replacement of flat-pack components
To repair a soldered joint, first apply heat while gently lifting the leads with a thin Kapton® or Teflon® sheet, moving from the non-soldered to the soldered section Next, remove any adhesive bonding as specified by NRB and clean the solder area with an approved solvent Inspect the joint for raised areas and overheated solder, repairing any raised surfaces according to Annex E, and remove overheated solder by wicking before re-tinning the area Position the new component, tack it for stability if necessary, and solder it in place using a heat-controlled soldering iron or a reflow machine with a peg-tip if space permits Finally, apply new adhesive as required by the component size, following clause 8.1.2 of ECSS-Q-ST-70-08.
Figure K-1: Removal of flat-pack components
Annex L (informative) Modification of component connections
Introduction
Modification of the connections from components to the printed circuit board can be required for the same reasons as those given in clause I.1.
Tools and materials
• approved solvent and cleaning brushes,
• approved epoxy paste staking compound,
Methods for modification of component connections
L.3.1 Method for the soldering of a wrap-around connection to an extended component lead a Using lint-free paper, mask as much as possible of the circuitry surrounding the area to be worked b Carefully remove any conformal coating from the area to be worked Use the method described in Annex A c Remove existing component in the location at which a wrap around connection is required Use the method described in Annex J Replace with a new component with lead extended in the “Z”-direction (refer to Figure L-1) d Strip, pre-tin (with use of a heat sink to prevent wicking) and form space-approved insulated wire for wrap-around connection to extended lead e Solder wire to extended component lead using a wrap-around connection as per clause “Turret and straight pin terminals” of ECSS-Q- ST-70-08 f Clean soldered area with approved solvent g Inspect in conformance with clause 12 of ECSS-Q-ST-70-08 h Position wire connection on board and bond to the board as defined in Annex H i Re-apply conformal coating and cure in conformance with the manufacturer data sheet
Component replaced and lead extended
Figure L-1: Soldering of a wrap-around connection to an extended component lead
L.3.2 Method for the soldering of component lead to a stud lead mounted into an existing hole a Pre-tin and solder a suitable diameter plain copper wire into the plated through hole b Mount component by attaching component lead to stud lead using a wrap-around connection (refer to Figure L-2) as per clause “Turret and straight pin terminals” of ECSS-Q-ST-70-08 c Clean soldered area with approved solvent d Inspect in conformance with clause 12 of ECSS-Q-ST-70-08 e Ensure stress relief is provided in component lead
Component with lead diameter great er than that of exist ing hole
Figure L-2: Soldering of component lead to a stud lead mounted into an existing hole
L.3.3 Method for mounting a dual-in-line (DIL) package with or without a wire link soldered onto a cropped lead a Using lint-free paper, mask as much as possible of the circuitry surrounding the area to be worked b Remove the existing DIL package Use the method described in Annex J c As required, crop leads of a replacement component in line with the bottom of the component body as shown in Figure L-3 (The component may be of either a “J”-lead or a “side-brazed” lead configuration) d De-gold and pre-tin the leads in two operations in conformance with clause 7 of ECSS-Q-ST-70-08 If connection of cropped leads to the board is required, then de-gold and pre-tin the cropped leads by hand For cropped side-brazed leads de-gold and pre-tin the entire lead shoulder (but this does not necessarily include the gold-plating on the braze fillet) e Solder the replacement component into position If no connection of cropped leads to the board is required, proceed to step h f Strip, pre-tin (with use of a heat sink to prevent wicking) and form space-approved insulated wire for connection of cropped leads to board g Solder wires to cropped leads to form a lap joint Wires may be led down onto the board or may pass away from the board (refer to Figure L-3 and Figure L-4) Use the lap joint with a length of three times the stripped wire diameter For cropped “J”-leads, solder for not ore than 3 seconds at a tip temperature of (250 ± 5) °C For cropped “side-brazed” leads, solder for not more than 3 seconds at a tip temperature of (295 ± 5) °C h Clean soldered area with approved solvent i Inspect in conformance with clause 12 of ECSS-Q-ST-70-08 Position wire connections on board and bond to the board as defined in Annex H j Re-apply conformal coating and cure in conformance with the
New component with cropped leads
Showing one cropped lead without connection and one cropped lead with wire connection
Mounting a dual-in-line package (DIP) can be done with or without a wire link soldered onto a cropped lead This process involves handling cropped leads that may either remain unconnected or connect through a hole onto the board.
Insulated wire New component with cropped lead
Figure L-4: Mounting a dual-in-line package with or without a wire link soldered onto a cropped lead (wire link passing away from board)
L.3.4 Method for mounting a connector with or without a wire link soldered onto a cropped lead a Using lint-free paper, mask as much as possible of the circuitry surrounding the area to be worked b Remove the existing connector from the board Use the method described in Annex J c As required, crop leads of a replacement connector as shown in Figure L-
5 d De-gold and pre-tin connector leads, including cropped leads, if connection of cropped leads to the board is required e Solder the replacement connector into position If no connection of cropped leads to the board is required, proceed to step h f Strip, pre-tin (with use of a heat sink to prevent wicking) and form space-approved insulated wire for connection of cropped leads to board g Solder wires to cropped leads using a wrap-around connection as per clause “Turret and straight pin terminals” of ECSS-Q-ST-70-08 h Clean soldered area with approved solvent i Inspect in conformance with clause 12 of ECSS-Q-ST-70-08 j Position wire connections on board and bond to the board as defined in Annex H k Re-apply conformal coating and cure in conformance with the manufacturer data sheet
New connector with cropped lead
Figure L-5: Mounting a connector with a wire link soldered onto a cropped lead
L.3.5 Method for the addition of a wire link into a plated-through hole occupied by a flat-section lead
To successfully insert a wire link into a hole occupied by a round-section lead, begin by masking the surrounding circuitry with lint-free paper Next, remove the conformal coating around the plated through hole using the method outlined in Annex A De-solder the lead in the hole as described in Annex B Prepare insulated AWG 30 wire by stripping, pre-tinning (with a heat sink to prevent wicking), and forming it for the link Insert the wire into the plated through hole alongside the existing component lead, ensuring it can enter from either side of the board, as shown in Figures L-6 and L-7 Solder the wire or component lead in place, then clean the soldered area with an approved solvent Finally, inspect the work in accordance with clause 12 of ECSS-Q-ST-70-08 and position the wire link on the board, bonding it as specified in the annex.
H i Re-apply conformal coating and cure in conformance with the manufacturer data sheet
Component with flat- section leads
Figure L-6: Addition of a wire link into a plated through hole occupied by a flat-section lead (wire link entering from the reverse side of the board)
Component with flat- section leads
Figure L-7: Addition of a wire link into a plated through hole occupied by a flat-section
L.3.6 Method for the addition of a wire link on top of a flat-pack lead a Using lint-free paper, mask as much as possible of the circuitry surrounding the area to be worked b Remove conformal coating from the area surrounding the flat-pack lead requiring addition of a wire link Use the method described in Annex A c Strip, pre-tin (with use of a heat sink to prevent wicking) and form space-approved insulated wire for making a link on top of the flat-pack lead d Place the section of the wire to be soldered along the centre line of the lead and solder into this position (refer to Figure L-8 and, for the solder fillet appropriate for a lap joint, Figure I-1 and Figure I-2) Use a wire with diameter less or equal to two thirds lead width e Clean soldered area with approved solvent f Inspect in conformance with clause 12 of ECSS-Q-ST-70-08 g Position wire link on board and bond to the board as defined in Annex
H h Re-apply conformal coating and cure in conformance with the manufacturer data sheet
Wire soldered on top of flat-pack lead
Figure L-8: Addition of a wire link on top of a flat-pack lead
L.3.7 Method for the isolation of a component lead
The "drilling-isolation" method is essential for effective component replacement Begin by masking the surrounding circuitry with lint-free paper and then remove the existing component as outlined in Annex J Drill out plated through holes using a hand-held drill, ensuring it is held vertically; for instance, a 1.1 mm diameter drill is suitable for a 0.75 mm hole Carefully remove pads on both sides of the board with a new scalpel blade, avoiding any damage to the glass fibers Continue drilling with a larger drill, such as a 1.3 mm diameter, and use a vacuum cleaner to clear away debris Insert Teflon® sleeve tubing into the drilled holes to isolate the lead, maintaining a minimum distance of 0.5 mm Place the new component with its leads through the isolated holes and solder the remaining leads If necessary, attach insulated wire to the isolated lead using a wrap-around connection as specified in ECSS-Q-ST-70-08 Clean the soldered area with an approved solvent, inspect according to clause 12 of the same standard, and spot bond the component and wire connections with epoxy staking compound, curing as required Finally, reapply conformal coating and cure according to the manufacturer's data sheet.
Figure L-9: Isolation of a component lead
L.3.8 Method for the addition of a wire link onto terminal pad of soldered chips a Flux the chip solder joint with brush b Solder silver wires or insulated wires (refer to Figure L-10) over a length greater than 1,2 mm c Clean soldered area with approved solvent d Inspect joint in conformance with clause 12 of ECSS-Q-ST-70-08 e Position the extended wire on the board and bond to the board by using a suitable space-approved adhesive (epoxy spot) Bond the lead along its length at intervals of not more than 3 cm, if it is longer than 3 cm Make the first spot bond of the extension wire just after the wire stress relief f Re-apply conformal coating and cure in conformance with the manufacturer data sheet
Figure L-10: Addition of a wire link onto terminal pad of soldered chips
Annex M (informative) Cutting of internal track of a multi-layer printed circuit board
Introduction
This procedure can be used when it is necessary to interrupt an internal connection of a multi-layer printed circuit board.
Tools and materials
• approved solvent and cleaning brushes,
• approved PCB repair facility (work station), including a milling attachment, and
Method for cutting the internal track of a multi-layer printed circuit board
To work on a printed circuit board, begin by masking the surrounding circuitry with lint-free paper Carefully remove any conformal coating from the designated area using the method outlined in Annex A Mill through the board's layers progressively to ensure clear visibility of layer separation and prevent shorts from burrs, while using a vacuum cleaner to eliminate swarf Once visibility of the internal track is achieved, cut the track and verify that the resistance exceeds 2 MΩ, ensuring no damage occurs to mounted components during electrical monitoring Afterward, remove the protective paper, clean the milled area with an approved solvent, and fill the hole with an epoxy compound, allowing it to cure according to the manufacturer's data sheet Finally, reapply the conformal coating and cure it as specified by the manufacturer.
Dimensions are for guidance only
Figure M-1: Cutting of internal track of a multi-layer circuit board
EN reference Reference in text Title
EN 16601-00 ECSS-S-ST-00 ECSS system — Description and implementation and general requirements