| I. The origin and status of international norms |
Both supply and demand of circuit board quality inspection of their own written standard, usually the most hard-board world wide industry with the international norms that are about three; that the United States Army Regulation MIL-P-55110, IEC-326-5/-6 and IPC- RB-276 and so on.
MIL-P-55110 has published more than 30 years, the Department of the earliest and most board and influence the credibility of the formal specification. The latest version of its 1993 E content of very interesting, important to the industry must-read documents, but unfortunately in recent years, the pace of the gradual loss of color behind the times.
IEC-326 as the "International Electrotechnical Commission" (IEC) has launched a total of 11 reports on the PCB of the series of specifications. Bones is dominated by the beating Africans for the world to vote by Member States under the product of consultation, the content is not strict provisions also less detailed, with a few assault outlets are generally more needy reference.
IPC of the original for the United States, "Printed Circuit Board Association" (Institute of Printed Circuit) is the abbreviation, when only six founding corporate members. After years of growth and absorption of foreign members of the group has grown to six thousand members of the large-scale international academic organizations, and changed its name to "The Institute for Interconnecting and Packaging Electronic Circuits". Published its board of various quality, technology, research, and market research and other documents are many, and for the global electronics industry relies on the upstream and downstream. However, many of its wonderful set of norms and documents, and misguide is from a number of large U.S. electronics company, after a face-lift into a seemingly "open and fair" information, in fact, facilitate promotion of American culture in the world, namely, IPC specifications innovative and practical One of the reasons.
IPC rigid circuit board about the quality of specification, the original single-sided of the IPC-D-250, and the multilayer IPC-ML-950 and other two, after twenty years, several versions of the amendment until 1992 March was then integrated into a single system, IPC-RB-276. November 1994 276 partial revision of the original launch of Amendment 1, the actually text in the revision of the 276A does not appear before the temerity to new designations will not long be generally good system of runoff line 276 abandoned, but start all over again to open up brand new IPC -6011, and IPC-6012, a considerable violation of norms of ethics, the reason is that outsiders can not easily.
Second, the new regulations new things finished before the IPC Board of official hard goods seized documents IPC-RB-276, Department released in March 1992, the popular industry attention. Between July 1996 has been split into IPC-6011 and IPC-6012 specification as the two new successor.
6011 of the former entitled "Overview of the circuit board performance specification" describes only the number of classification, tolerances, SPC, quality assurance administration, sampling plans and other provisions in principle, did not address the practical test PCB. The latter 6012 entitled "The rigid PCB and property for accreditation", the Department of rigid plates for a variety of practice quality, set acceptance specifications and test procedures. Changes now evident in the new specification content are described below:
2.1.1 The new 6011 and 6012 two specifications seem to wish to avoid the original "American military regulations" clause to get rid of the military regulations. As in the 6011 classification in Section 1.2 of the note, that the provisions of deliberately from the three board classes will "Military" words removed. Another section 3.1 in 6011, also cited in the original military specifications in Group A and Group B to be removed, the real cause is unknown, but may be obvious who is the hope that advanced PCB are not subject to military regulations of. However, the wording left the whole chapter is still very ambiguous word wordy, obscure mystery and feared by his best is not off Army regulations simplified the complicated bureaucratic rut.
2.1.2 6011 of 3.6 pairs of new "accreditation" has to be more clearly defined, subject to IPC-MQP-1710 list of the contents of the careful engineering capabilities of the PCB producers, production equipment, quality control practices carried out extensive research. Specification than the old play just asked to do a few slices of a model (such as IPC-A-100047, etc.) do many practical, vendor contracting capability established clear evidence of how the strengths and weaknesses.
2.1.3 New section 6011 of 220.127.116.11, in addition to both supply and demand position, but also the independence and impartiality of the "third reviewer," such as ISO, CSA, IECQ, etc. included. Also even in the 3.7 ISO -9000 standard of civilization that quality assurance system. A reversal of the past consider themselves America's most outstanding, the industry turned a blind eye to the assault Island mentality, which is probably also the "European style" command and drinking places shortly after the establishment of the impact of it.
2.2.1 new 6012 added a number of goods seized is not clear that the conditions of the project were (Default), but also the most widely used on behalf of the conditions specified on the individual shown in Table 1.1. Such as the lower limit for the linewidth 4mil, acceptance test of solder can be accessed by J-STD-003 of the Catagory 2 and 6012 will be cited in the IPC-TM-650 test in reality a number of ways to do, the translator also according to the latest version (1997.8 ) outlined the steps the data, so that readers can quickly obtain specific practical ideas. Please pay special attention to the industry here, many of the scene has been a common test from time to time you may not know. To keep up with this translation can be outlined for the IPC-TM-650 latest version, you can be compared with that amendment.
2.2.2 in the 3.2.7 section of the new 6012 will be bare copper, "organic solderability preservative" (Organic Solderability Preservatives referred to as commodity Entek OSP, etc.) approach for the first time included in the official specification.
2.2.3 in Table 3.2 in the new 6012 Copper Electroplating "thickness", has been a major change in the general Class 2 board (such as computer products are) the surface of copper and copper hole "average thickness" has been reduced to 0.8 mil 1mil ; lower and more reduced to 0.7mil. This is popular because of deep holes, hole copper thickness requirements difficult to meet due. Over the years the taboo has finally been broken, break military regulations also bound the evidence of the industry will have a significant impact. For the process to shorten, automatic transmission, etc. The Rising levels of copper are very favorable. Class 2 of the table or even to the blind hole sheet metal (Blind Via) average copper thickness relaxed 0.6mil, lower limit can be thin to 0.5mil. Small and thin multilayer class is indeed very good news. In 3.11.8 the other requirements of the copper layer is also clearly set at 99.5%, the tensile strength of not less than 36000 PSI; elongation of not less than 6%. The Table 3.2 on the finger of the other end of the thickness of nickel dropped from the 0.2mil 0.1mil (Class 2 and Class 3 category were also relaxed the two plates).
New 6012 Section 2.2.4 has been firmly in 18.104.22.168 that the inner plate surface of the "black oxide" that often appear in spots and color, when these flaws on the same floor area does not exceed the total area of 10 black % should be acceptance. But the fact is that reasonable changes, but it is difficult to see the truth behind the appearance of the customers accepted.
2.2.5 New in 3.4.4 in 6012, also on the board cancel the original Alice bending the upper limit of 1.5% of outdated, and the other to SMT board class for several years form the upper limit of 0.75% of all the official text. This is in fact consistent with the fact that assembly of the status of reaction only, not tightening the original flatness of cartridge type scale.
2.2.6 new 6012 notes in its 22.214.171.124, expressly noted that its thinnest multilayer thin dielectric layer can be thin to have 1mil (specified in the original 276 of the 126.96.36.199 not be less than 2mil), also goes to some reaction the fact sheet (such as some six board PCMCIA only 18mil thick). And 3.7.2 of this section of the new regulations, but also clearly pointed out many times on the through-hole soldering and de soldering plug the "analog Heavy" reliability test, there should only be for the board through-hole soldering and do not be troubled SMT BGA solder or other non-plug board class.
2.2.7 New in 3.8 in 6012 the provisions of the green paint, than the original IPC-RB-276 is more detailed in 3.11, it also highlighted the importance of the green paint. Also in section 3.8.1 in the special provisions of paragraph f.1, green paint stick to climb SMT deliberate or accidental, or BAG round square pad when the pad, where the pitch (Pitch) in 50mil or more, the climbing stick The width of no more than 2mil; foot climb in less than 50mil who stick their width must be less than 1mil. These two models than the original 276 in the 3.11.1.f 4mil allowed many to be strict. The green paint thickness requirements, 6012 and IPC-SM-840C also relaxed, no longer insists on 4mil Class 2 minimum thickness of sheet metal. But pointed out that when customers need to measure the thickness, then should from it.
2.2.8 and 3.9.1 the new 6012 "Media-resistant voltage" within the text, for 3mil following ultra-thin dielectric layer, to test the voltage down from the 500 Vdc 250 Vdc; For more than 3mil dielectric layer is still maintained Pressure of the original 500 Vdc.
2.2.9 RB-276 will be the original "hot shock Thermal Shock" provision under section 3.12.2 3.13 in the environmental testing. Therefore, the new 6012 will be compiled in the section 3.11.9 is a "special request" category, may feel more reasonable.
2.2.10 of the original RB-276 on the connectivity in the 188.8.131.52 (Continuity) requirements, such as the Class 2 category of the resistance plate is not more than 50 ohmic. In the new 6012 is another in 184.108.40.206 IPC-ET-652 according to the provisions, rather than listing specific values. 220.127.116.11 The isolation is also another quasi forth.
2.2.11 In its new 6012 mentioned in section 4.2 and 4.2.1 the so-called C = 0 sampling plan, and list the number of samples express 4.2. The integrity of the quality specifications, the sampling plan appears to be an integral part; but PCB has always been 100% of all seized, the customer is difficult to accept because of sampling problems and missed the board, unfortunately, this new specification is still is throwing the burden can not afford this nonsense.
Third, the conclusions of both supply and demand are a number of items to be seized there in consultation with the acceptance criteria, then fairly frequently because of legislation differences Airport or different views from time to time disputes. Latest IPC-6011 and IPC-6012, should be neutral as a powerful reference and evidence, is an important industry must-read document.