Système d'assurance de la qualité –Partie 1: Enregistrement et analyse des défauts sur les cartes imprimées équipées Quality assessment systems – Part 1: Registration and analysis of def
Critères d'acceptation
Les critères d'acceptation et de défaut sont établis dans les CEI 61191-1, CEI 61191-2,
CEI 61191-3 et CEI 61191-4 Les joints de brasage doivent être comparés avec ces critères.
Comptage des défauts
Le comptage des défauts sur le produit est effectué au niveau du joint de brasage Le joint de brasage qui ne répond pas aux normes est compté comme défaut.
In the case of bridging, it is an exception to the standard counting method A bridge between two outputs (or between a solder pad and a conductor) is counted as a single defect (one bridge), while a bridge between three outputs is counted as two defects (two bridges), and so on.
4 Les ponts (courts-circuits) sont des connexions entre des parties métalliques créées par le brasage; elles sont involontaires et ne sont pas prescrites pour la conception.
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Tombstoning (S4) occurs when an electronic or electromechanical component fails to adhere properly during attachment, resulting in one end of the component being elevated off the land This issue arises when one or more terminations cool faster than others, leading to an uneven solidification process.
A damaged component (S5) refers to an electronic or electromechanical part that fails to meet the original specifications set by the supplier This nonconformance can result from issues such as improper solder attachment, mishandling during assembly, or exposure to harmful conditions during the assembly process.
A damaged printed board (S6) refers to an interconnecting structure that fails to meet the original specifications for the unpopulated product This damage may result from issues such as the solder attachment process, mishandling during assembly, or exposure to harmful conditions during the assembly process.
3.5.7 solder wicking (S7) capillary movement of solder between metal surfaces, such as strands of wire, plated-through holes, surface land patterns, or electronic/electromechanical component terminations
3.5.8 disturbed solder joint (S8) solder connection that is characterized by the appearance that there was motion between the metals being joined when the solder was solidifying
Solder balls, splashes, and webs (S9) refer to unwanted solder fragments that can appear as small balls, irregular shapes, or a continuous film that runs parallel to a surface These extraneous solder materials should not be present on surfaces that are intended to remain free of solder.
3.5.10 bad wetting (S10) lack of the formation of a relatively uniform, smooth, unbroken, and adherent film of solder to a basis metal, surface land pattern or an electronic/electromechanical component termination
For a uniform registration of defects, the following basic principles apply.
Accept /defect criteria as specified in IEC 61191-1, IEC 61191-2, IEC 61191-3 and IEC 61191-4.
Solder joints shall be evaluated with the accept/defect criteria.
Defects in the product will be assessed at the soldered joint level, with any joint failing to meet standards classified as defective.
In the context of defect counting, bridging 4 presents a unique exception When bridging occurs between two terminations or between a solder land and a conductor, it is considered a single defect Conversely, if bridging takes place between three terminations, it is classified as two defects.
4 Bridges (short circuits) are connections between metal parts created by solder which are unwanted and not required in the design.
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In the case of motherboards, there are instances where a portion of the printed circuit board is unused, as components are not placed in that specific area It is important to exclude this section from the defect count.
Enregistrement des défauts après brasage
Défauts trouvés après essai
Not all defects may be detected by the inspection methods employed after soldering, such as visual inspection, automatic optical inspection (AOI), or X-ray inspection.
Les défauts repérés au cours de ces contrôles, et imputés au processus d'assemblage, doivent être inclus lors de la détermination du taux de défauts de ppm après brasage.
When electrical testing occurs immediately after soldering, without any visual, optical, or X-ray inspection before rework or removal, the collected data should not be directly compared to data gathered during visual inspections conducted right after soldering.
Catégories de défauts
Origine des défauts
Les défauts à enregistrer sont classés suivant leur origine en fonction de la liste ci-après:
In this indexing, potential design, material, and process defects are primarily attributed to the aforementioned sources of faults Analyzing the recorded data may lead to further categorization of defects by process stages, component types, and more.
Formulaire d'enregistrement des défauts
L'enregistrement des défauts est effectué sur un formulaire qui est dérivé du dessin d'assemblage.
Les informations suivantes doivent figurer sur le formulaire:
– le nombre de défauts (à la position concernée);
– le nombre de cartes imprimées vérifiées.
Selon le niveau de défauts, un formulaire peut être utilisé:
– à partir d'une autre unité de production.
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NOTE 2 In the case of family boards, sometimes a part of the printed board is not used (components are not placed in this particular area) The content of any deliberately unused part of the board should be excluded from the counting of defects and the total number of solder joints.
Post-soldering defect registration should be made immediately after the soldering process, before any recheck The soldered product is checked before any repair.
It is possible that not all defects are detected by the post-soldering inspection methods used, for example, visual inspection, automatic optical inspection (AOI) or X-ray inspection.
Defects that are found during these inspections and that can definitely be ascribed to the assembly process, shall be included when determining the post-soldering ppm defect rate.
Electrical testing conducted right after soldering, without any visual, optical, or X-ray inspection before rework or scrapping, yields data that is not directly comparable to data collected when visual inspection follows soldering as the first activity.
The defects to be registered are subdivided into the following defect sources:
In this registration, potential design, material, and process defects are initially attributed to the identified defect sources Analyzing the recorded data allows for further categorization of defects by process step, component type, and more.
The defect registration is made on a form that is derived from the assembly drawing.
The following information shall be reported on the form:
– the position of the defect;
– the number of defects (at the relevant position);
– the number of checked printed boards.
Depending on the level of the defects, one form can be used:
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Retouches immédiates pour le brasage
Quand il y a des défauts de brasage, l'assembleur doit déclarer chaque retouche à effectuer entre le placement/insertion du composant et les opérations de brasage.
Accept criteria
Accept /defect criteria as specified in IEC 61191-1, IEC 61191-2, IEC 61191-3 and IEC 61191-4.
Solder joints shall be evaluated with the accept/defect criteria.
Counting of defects
Defects in the product will be assessed at the soldered joint level, with any joint failing to meet standards classified as defective.
In the context of defect counting, bridging between two terminations or between a solder land and a conductor is considered a single defect, while bridging among three terminations is counted as two defects.
4 Bridges (short circuits) are connections between metal parts created by solder which are unwanted and not required in the design.
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In the case of motherboards, there are instances where a portion of the printed circuit board remains unused, as components are not placed in that specific area It is important to exclude this section from the defect count.
4.3 Enregistrement des défauts après brasage
L'enregistrement des défauts est effectué après le processus de brasage (avant la retouche).
Le produit de brasage est vérifié avant toute réparation.
It is possible that not all defects are detected by the inspection methods used after soldering, such as visual inspection, automatic optical inspection (AOI), or X-ray inspection.
Les défauts repérés au cours de ces contrôles, et imputés au processus d'assemblage, doivent être inclus lors de la détermination du taux de défauts de ppm après brasage.
When electrical testing occurs immediately after soldering, without any visual, optical, or X-ray inspection prior to rework or removal, the collected data should not be directly compared to data gathered during visual inspections conducted right after soldering.
Les défauts à enregistrer sont classés suivant leur origine en fonction de la liste ci-après:
In this indexing, potential design, material, and process defects are primarily attributed to the aforementioned sources of faults Analyzing the recorded data may lead to further categorization of defects by process stages, component types, and more.
L'enregistrement des défauts est effectué sur un formulaire qui est dérivé du dessin d'assemblage.
Les informations suivantes doivent figurer sur le formulaire:
– le nombre de défauts (à la position concernée);
– le nombre de cartes imprimées vérifiées.
Selon le niveau de défauts, un formulaire peut être utilisé:
– à partir d'une autre unité de production.
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In family boards, certain areas of the printed circuit board may remain unused, meaning components are not placed in those sections Consequently, any intentionally unused portions should not be included in the defect count or the total number of solder joints.
Post-soldering defect registration
Defects found after testing
It is possible that not all defects are detected by the post-soldering inspection methods used, for example, visual inspection, automatic optical inspection (AOI) or X-ray inspection.
Defects that are found during these inspections and that can definitely be ascribed to the assembly process, shall be included when determining the post-soldering ppm defect rate.
Electrical testing conducted right after soldering, without any visual, optical, or X-ray inspection before rework or scrapping, yields data that is not directly comparable to data collected when visual inspection follows soldering as the first activity.
Defect subdivision
Defect sources
The defects to be registered are subdivided into the following defect sources:
In this registration, potential design, material, and process defects are initially attributed to identified defect sources Analyzing the recorded data allows for further categorization of defects by process step, component type, and more.
Defect registration form
The defect registration is made on a form that is derived from the assembly drawing.
The following information shall be reported on the form:
– the position of the defect;
– the number of defects (at the relevant position);
– the number of checked printed boards.
Depending on the level of the defects, one form can be used:
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4.5 Retouches immédiates pour le brasage
Quand il y a des défauts de brasage, l'assembleur doit déclarer chaque retouche à effectuer entre le placement/insertion du composant et les opérations de brasage.
4.6 Enregistrement des catégories de défauts
Les défauts doivent être enregistrés en deux catégories.
Category 1 encompasses all defects identified after soldering, regardless of their origin or nature This data is intended for general comparisons of the entire control and quality process across various production lines.
Soldering is defined as the result of reflow, immersion (such as wave, jet, or selective soldering), and/or manual soldering While some post-soldering defects may not be related to the solder joint itself (for instance, defects in the board or component), the calculations for the ppm level in category 1 are based on the number of solder joints on the printed circuit board.
Category 2 encompasses all data related to the complete sequences of processes Analyzing this recorded data can lead to classifications such as defects by process step and defects by component type In this context, the preliminary steps before the soldering process are defined as elementary processes The lines used to calculate the ppm level for Category 2 vary depending on the involved process Please refer to Appendix A.
The data collected is utilized to determine the parts per million (ppm) level of the verified production unit The ppm level of a production batch is defined as follows: \$$\text{ppm}_{\text{product}} = \left( \frac{\text{number of defects identified during 100% inspection}}{\text{total number of joints soldered in the production batch}} \right) \times 10^6\$$ This formula calculates the total number of defects in relation to the production output.
The total number of produced cards is multiplied by the number of verified random cards to assess the defects identified during the inspection process Additionally, the total number of produced cards is multiplied by the number of solder joints per card to evaluate the overall quality of the assembly.
In the context of random verification, the reliability of the calculated parts per million (ppm) is contingent upon the extent of the random checks and the actual ppm levels Therefore, ppm levels derived from random verification should include a confidence interval or specify the number of solder joints inspected.
NOTE 1 Pour être en mesure de comparer entre eux les divers produits en termes de temps, il convient que les données soient converties selon la même unité de temps.
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Rework immediately prior to soldering
When presenting post-soldering defects, the assembler shall state whether any rework is carried out between component placement/insertion and soldering operations.
Defect data categories
The defects to be registered are subdivided into two categories.
Category 1 includes all post-soldering defects, irrespective of their origin or type This information is designed for a general comparison of the overall process control and quality output across various production lines.
Soldering is characterized by processes such as mass reflow, mass immersion (including wave, jet, and drag methods), and manual techniques While certain post-soldering defects may stem from issues unrelated to the solder joint, such as defects in the board or components, the baseline for calculating Category 1 parts per million (ppm) data is determined by the total number of solder joints on the printed circuit board.
Category 2 comprises the entire body of data relating to the whole process sequence.
Analyzing the registered data can facilitate the categorization of defects by process step and component type In this analysis, the steps leading up to soldering are considered subprocesses The baselines for calculating Category 2 ppm data differ based on the specific process used For more details, please refer to Annex A.
The data collected is utilized to calculate the parts per million (ppm) level of the inspected production unit The ppm level for a production lot is defined as the total number of defects found during a 100% inspection divided by the total number of joints soldered, multiplied by 10^6.
The quality assessment of produced boards is determined by the ratio of boards checked for defects to the total number of soldered joints This is calculated by multiplying the number of produced boards by the number of soldered joints per board.
The reliability of ppm calculations is contingent upon the scope of the random check and the actual ppm level Therefore, ppm levels derived from random checks must either incorporate a confidence interval or specify the number of inspected soldered joints.
NOTE 1 To be able to compare the various products with each other over time, the data should be converted to the same time unit.
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NOTE 2 Le calcul du niveau moyen de ppm pour la production de divers types de cartes imprimées (par exemple A, B, C) est effectué comme suit:
– Nombre total de défauts de brasage = nombre de défauts sur le type A + nombre de défauts sur le type B + etc.
The total number of solder joints is calculated by multiplying the number of produced type A cards by the number of solder joints for type A, adding the product of the number of produced type B cards and the number of solder joints for type B, and continuing this process for all card types.
L'annexe C contient des exemples pratiques.
The Pareto analysis method helps assess how various types of defects contribute to the overall defect level In addition to categorizing by defect type, it can also be segmented by component type A practical example can be found in Appendix D.
La subdivision en défauts peut être utilisée pour analyser (éventuellement avec une sub- division supplémentaire) l'origine des causes éventuelles (conception, matériaux, processus, etc.).
To analyze the contribution of elementary processes to the total defects, it is essential to attribute defects to these processes for effective data handling Defect causes in materials and design can be addressed accordingly However, this analysis requires a comprehensive understanding of the entire manufacturing process Definitions of defects arising from various elementary processes are provided in the IEC standards 61191-1, 61191-2, 61191-3, 61191-4, 61192-1, and 61192-2.
CEI 61192-3 et CEI 61192-4 Certains défauts sont résumés à l'annexe B.
Si seuls les processus élémentaires sont analysés, alors les défauts doivent être mis en relation avec les opérations qui sont effectuées dans ce processus élémentaire (voir annexe A).
L'analyse de Pareto indique ó il convient que l'ingénieur de processus fasse une correction.
To enhance quality levels, it is essential to first address the defects that significantly contribute to the overall defect rate Additionally, it is important to eliminate minor defects that are easily repairable The ultimate goal should always be to achieve the lowest possible defect level.
Le niveau de ppm d'un produit peut être suivi en termes de temps Cela indique les tendances Les divers produits peuvent être comparés entre eux au moyen d'un graphe
(niveau ppm par rapport au temps) et traduire la qualité complète de l'opération de fabrication La figure D.5 fournit un modèle.
Monitoring product defect rates over an extended period offers insights into the threshold conditions and quality levels necessary for successful production It is essential to utilize these threshold conditions, which are based on process orders related to design, materials, and procedures, to enhance fundamental principles This approach ensures that new products begin their production with a lower defect rate.
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NOTE 2 The calculation of the average ppm level for the production of various types of printed boards (for example A, B, C) is effected as follows:
– Total number of soldered defects = number of defects on type A + number of defects on type B + etc.
– Total number of soldered joints = number of produced boards type A × number of soldered joints on type A + number of produced boards type B × number of soldered joints on type B + etc.
Annex C contains worked-out examples.
Pareto analysis is an effective method for evaluating the contribution of different defect types to the overall defect level This approach allows for categorization not only by defect type but also by component type For a detailed example, refer to Annex D.
Subdivision into defects can be used to analyse (possibly using a further subdivision) where the possible causes originate from design, materials, process, etc.
To analyze the contribution of subprocesses to the total defect level, it is essential to allocate defect data to these subprocesses Defect causes related to material and design should be addressed accordingly This analysis requires a comprehensive understanding of the entire manufacturing process, with definitions of defects from various subprocesses outlined in IEC 61191-1.
IEC 61191-2, IEC 61191-3, IEC 61191-4, IEC 61192-1, IEC 61192-2, IEC 61192-3 and
IEC 61192-4 Some of the defects are summarized in annex B.
If only the subprocesses are analysed, then the defects shall be related to the operations of process steps that are carried out in that subprocess (see annex A).
Pareto analysis helps process engineers identify where to concentrate corrective actions for quality improvement Prioritizing the resolution of defects that significantly contribute to the overall defect level is essential, while also addressing minor defects that are easier to fix The ultimate objective is to minimize the defect level as much as possible.
Monitoring the ppm levels of a product over time allows for the identification of trends and facilitates comparisons between different products through graphical representation (ppm level vs time) This approach offers a comprehensive quality history of the manufacturing process, as illustrated in Figure D.5.