In the IPC's Technical Activities Executive Committee adopted Principles of. Standardization as a guiding principle of IPC's standardization efforts. IPC-AG. Acceptability of. Printed Boards. Developed by the IPC-A Task Group (a) of the Product. Assurance Committee () of IPC. Users of this. PURPOSE. • The visual illustrations in this document portray specific criteria of the requirements of current IPC specifications. In order to properly apply and use .
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The IPC-A Training and Certification Program helps all segments of the electronics Download the course synopsis (schedule format) .pdf). All IPC-A- 1, View Account▹ · Home; IPC AJ. Preview Priced From (in USD). Secure PDF. ℹ IPC AG. July Acceptability of. IPC Standards and Publications are designed to serve the public interest through eliminating mis- understandings IPC-A Acceptability of Printed Boards.
This document, IPC-A, is a companion and complementary document, providing pictorial interpretation of these requirements. IPC-A can be used as a support document for inspection. It does not specify frequency of in-process inspection or frequency of end product inspection. Visual examination for applicable attributes shall be conducted at 3 diopters approximately 1.
If the acceptable condition of a suspected defect is not apparent, it should be verified at progressively higher magnifications up to 40X to confirm that it is a defect.
Dimensional requirements such as spacing or conductor width measurements may require other magnifications and devices with reticles or scales in the instrument, which allow accurate measurements of the specified dimensions. Contract or specification may require other magnifications.
Plated-through holes shall be internally examined for foil and plating integrity at a magnification of X. Referee examinations shall be accomplished at a magnification of X. Automated Inspection Technology AIT results may be applicable to the evaluation of many of the dimensional characteristics illustrated in this document.
The revision of the document in effect at the time of solicitation shall take precedence. Dimensions are expressed in hard SI metric units and parenthetical soft imperial [inch] units. Reference information is shown in parentheses. Printed boards shall be free of defects in excess of those allowed by this document. Acceptance of imperfections not specifically covered by this document shall be agreed upon by the user and supplier of the product. This includes those characteristics that are external and internal in the printed board but visible from the surface as follows: Surface Imperfections such as burrs, nicks, scratches, gouges, cut fibers, weave exposure and voids.
J-STD-001D: Rev D superseded by Rev E
Imperfections in Conductive Pattern such as loss of adhesion, reduction of conductor width or thickness due to nicks, pinholes, scratches, surface plating or coating defects.
Hole Characteristics such as diameter, misregistration, foreign material, and plating or coating defects. Marking Anomalies including location, size, readability, and accuracy. Solder Resist Surface Coating Imperfections such as misregistration, blisters, bubbles, delamination, adhesion, physical damage and thickness.
Dimensional Characteristics including printed board size and thickness, hole size and pattern accuracy, conductor width and spacing, registration and annular ring. Acceptable Class 1, 2, 3 Edge conditions rough but not frayed. Edge conditions - loose burrs do not affect fit and function. Nonconforming Class 1, 2, 3 Defects either do not meet or exceed above criteria.
Acceptable Class 1, 2, 3 Edge condition - rough but not frayed. Edge condition - no loose burrs. Acceptable Class 1, 2, 3 Edges are rough but not frayed.
To help identify those conditions, refer to the following sections where definitions, illustrations and photographs have been provided which precisely define and identify the following conditions: Surface 2. Some defects may be induced during processing. The Use of Acceptability Criteria Everyone cannot be an expert on laminate defects.
Some nondestructive visual criteria must be established to aid in making a decision regarding acceptability levels. A surface condition of base material in which the unbroken fibers of woven cloth are not completely covered Acceptable Class 1, 2, 3 Excluding the area s with weave exposure, the remaining space between conductors meets the minimum conductor spacing requirement.
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IPCga Note: This graphic is for illustrative purposes only and does not require a microsection evaluation. Acceptable Class 1, 2, 3 Weave texture is an acceptable condition in all classes but is sometimes confused with weave exposure because of similar appearances.
This example could be either weave exposure or weave texture. The difference cannot be determined from this view. The difference can be discerned using nondestructive tests oblique illumination with microscope or microsection. Nonconforming Defects either do not meet or exceed above criteria. Acceptable Class 1, 2, 3 Pits or voids do not exceed 0. Pits or voids do not bridge conductors. The most frequent subsurface base materials conditions are termed measling, crazing, delamination, blistering and foreign materials.
Base material subsurface conditions have been the subject of considerable discussion within the printed board industry for several decades. Of the several subsurface conditions, measling and crazing continue to cause the most concerns. The following are brief summaries and additional comments from the IPC s Blue Ribbon Committee: Brief summary of the First IPC Blue Ribbon Committee on Measles The committee conducted a wide overview of printed board base material surface and subsurface conditions with a major focus on measles.
It was felt that sufficient research had been done by industry and that a position on measles could be prepared by the committee. The committee s recommendation was as follows, comprehensive review of available literature and available research and test data, that while measles may be objectionable cosmetically, their effect on functional characteristics of finished products, are at worst minimal, and in most cases insignificant.
Comments: Despite the committee s recommendation and industry data, there was still a strong reluctance by most government and industry personnel to accept that measles are a cosmetic condition with no functional effect in most applications. Most companies continued to retain no measling requirements in their specifications. The new guidelines were based on size, percent reduction in conductor spacing, and amount of affected area.
They also varied from customerto-customer. Brief summary of the Second IPC Blue Ribbon Committee on Measles The committee was formed in late This committee reviewed the findings of the first committee, solicited the industry for additional data, and reviewed the proprietary acceptance criteria provided by IPC members.
The Second Blue Ribbon Committee came to the same conclusion. Measles are a cosmetic process indicator and had almost no reported effects on a product s functional performance in most applications.
The major exception was high voltage applications. There was still reluctance by some government organizations and a few industrial companies to categorically accept measles. The result was a matrix of acceptance limitations for the three major phases of the printed board electronic assembly process: laminated material, printed board final inspection, and after printed board assembly.
These requirements included percent reductions in conductor spacing not exceeding minimum conductor spacing , and various amounts of measled area for each side of the printed board or assembly based on the Class of product.
Comments: The primary concerns expressed by the reluctant individuals are summarized in the following list with comments : Electrical Insulation Resistance, both volume and surface - several reports and available test data indicates that insulation resistance is not significantly affected by measling or crazing.
Contamination - the concern was that ionic materials could diffuse or be pumped by alternating atmospheric pressure into measles or crazing and would result in lower insulation resistance or conductive-anodic filament CAF growths, shorts. Salt spray tests indicated this was not a valid premise, and most ionic materials such as salts will not diffuse into the base material.
IPC-A, Revision E, was the first revision to reflect the needs for surface mounted component technology. As such, the acceptance requirements for measling and crazing were separated.
For measles, the acceptance requirements allowed bridging under surface conductor spacing. This was done based on the definition of measles, test data, and industry experience of measles having never been documented to cause a functional failure. Crazing is much less controlled separation in the base material forming interconnections between measles and possibly adjacent conductive patterns; therefore, the acceptance requirements for crazing were set the same as the similar conditions of delamination and blistering.
Over a period of time, governing specifications have become excessively heavy regarding the presence of measles. In addition, cosmetic appearance has become a major acceptance criterion.
In actual fact, no failure has ever been attributed to measling, based on all military and industry testing to date. IPC, industry and various military agencies have conducted extensive testing in severely measled assemblies under extreme environmental conditions for long periods of time with no evidence of growth, spreading or any detriment to the function of the assembly.
Measles should not be the cause for rejection. Measling is an internal condition occurring in the woven fiber reinforced laminated base material in which the bundles are separated at the weave intersection. The term crazing is sometimes used to describe an array of measles which appear from the surface to be interconnected. For nonwoven material, this condition resembles a measle but is randomly located and has an irregular shape see Figure 1.
In a case study done, the prime cause of the observed measles was a combination of moisture, which diffuses readily into epoxy-glass, and component soldering temperatures. The application of local high temperatures for component mounting caused entrapped moisture to vaporize and break the epoxy-glass bond at the knuckle intersection of the warp and fill of the e-glass cloth.
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From previous experience, it is known that epoxy-glass absorbs atmospheric moisture, and when moisture content exceeds 0. Why, if all test reports showed no problems with measles and no reported field failures, are we so concerned about measles and crazing?
Even when the potential failure mechanism mentioned above is analyzed, it is almost impossible to experience such insulation resistance IR or migration failure. First, a measle s gapping conductive patterns is needed. In this instance, a typical industry example, the measle is at the center between two plated through holes see Figure 2.
The measle is 0. In order to get possible copper migration, the measle had to gap the two plated through holes. This of course would be most unlikely. The second example see Figure 3 illustrates what is required for a potential failure mechanism between two surface conductors.
For an electrical short to occur between these conductors through the base material, there would need to be a conductive path from one conductive pattern, through the remaining dielectric materials resin and yarn to the separation measle , along the separation in the direction of the other conductive pattern, once again through the remaining dielectric materials resin and yarn , and to the second conductive pattern.
In order to induce a failure all of the above mentioned ingredients are required along with a voltage potential between two adjacent conductors. This occurrence is highly unlikely and is most likely why the industry has not experienced any adverse reliability problems due to measles mm [ in] 0.
When making acceptance calls on electronic hardware, consider all the possible concerns mentioned above. Measles should not be considered a nonconforming condition.
It should instead be considered a process indicator, telling you that the process is on the verge of going out of control. IPCgab Figure 1 Note: This graphic is for illustrative purposes only and does not require a microsection evaluation. Measles are subsurface phenomena that have been found in new laminated materials and in every board type made from woven fiber reinforced laminates at one time or another.
Since measles are strictly subsurface phenomena and occur as a separation of fiber bundles at fiber bundle intersections, their apparent positions relative to surface conductors have no significance.
Measling IPCge Note: This graphic is for illustrative purposes only and does not require a microsection evaluation. Acceptable Class 1, 2, 3 Measles are acceptable for all products, except for high-voltage applications as defined by the customer. Note: Measles are observed from the surface. Cross-sections are for illustration purposes only.
This can occur at the weave intersections or along the length of the yarn. This condition manifests itself in the form of connected white spots or crosses below the surface of the base material, and is usually related to mechanically induced stress.
When the crosses are connected the condition is evaluated as follows: Crazing Target Condition Class 1, 2, 3 No evidence of crazing. IPCge Note: This graphic is for illustrative purposes only and does not require a microsection evaluation. Acceptable Class 2, 3 The imperfection does not reduce the space between conductive patterns below the minimum conductor spacing. No propagation as a result of thermal testing that replicates the manufacturing process.
Crazing at the edge of the board does not reduce the minimum distance between board edge and conductive pattern; or more than 2. Acceptable Class 1 The imperfection does not reduce the space between conductive patterns below the minimum conductor spacing. Nonconforming - Class 1, 2, 3 Defects either do not meet or exceed above criteria.
Note: Crazing is observed from the surface. Delamination Blistering Blister: Delamination in the form of a localized swelling and separation between any of the layers of a lamination base material, or between base material and conductive foil or protective coating.
Note: This graphic is for illustrative purposes only and does not require a microsection evaluation. Target Condition Class 1, 2, 3 No blistering or delamination. The imperfection does not reduce the space between conductive patterns below the minimum conductor spacing. Number of pages: Released May It represents the visual interpretation of minimum requirements set forth in various printed board specifications, e.
In order to properly apply and use the content of this document, the printed board should comply with the design requirements of the applicable IPC series document and the performance requirements of the applicable IPC series document. In the event the printed board does not comply with these or equivalent requirements, then the acceptance criteria should be as agreed between user and supplier AABUS.
In some cases, such as voids or blisters, the actual condition is an internal phenomenon and is detectable from the exterior. In some cases, these features may be visible from the exterior and require microsectioning in order to assess acceptability requirements. Specimens should be illuminated during evaluation to the extent needed for effective examination. The illumination should be such that no shadow falls on the area of interest except those shadows caused by the specimen itself.
The illustrations in this document portray specific criteria relating to the heading and subheading of each page, with brief descriptions of the acceptable and nonconforming conditions for each product class. See 1. The visual quality acceptance criteria are intended to provide proper tools for the evaluation of visual anomalies. The illustrations and photographs in each situation are related to specific requirements.Measles are a cosmetic process indicator and had almost no reported effects on a product s functional performance in most applications.
Procurement documentation. For nonwoven material, this condition resembles a measle but is randomly located and has an irregular shape see Figure 1.
It represents the visual interpretation of minimum requirements set forth in various printed board specifications, e. The Second Blue Ribbon Committee came to the same conclusion. From previous experience, it is known that epoxy-glass absorbs atmospheric moisture, and when moisture content exceeds 0.
Manufacturers have to comply with many comprehensive inspection specifications that are in the IPC standard, and designers have to be careful about IPC Class 2 Vs Class 3 different design rules , for instance. The implementation of the Classes is done mostly by sorting product to the Class that is specified.
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