SMT007 Magazine

SMT007-Sept2019

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44 SMT007 MAGAZINE I SEPTEMBER 2019 Class II is defined as dedicated service elec- tronic products, which "includes products where continued performance and extended life is required, and for which uninterrupted service is desired but not critical. Typically, the end-use environment would not cause fail- ures." Class II products would be found in a lot of automotive electronics, not related to safety, as well as harsh environment electron- ics that may not necessarily be life-critical but are expected to operate for 20+ years. Class III is defined as "products where con- tinued high performance or performance-on- demand is critical, equipment downtime can- not be tolerated, the end-use environment may be uncommonly harsh, and the equipment must function when required, such as life sup- port or other critical systems." These electron- ics are most commonly found in industries like healthcare and aerospace. When your life, or the life of others, is on the line, Class I simply won't do. The standards for assembling Class II and III are well known with IPC J-STD-001 being the cornerstone of the J-STD series of standards. J-STD-001 is titled "Requirements for Soldered Electrical and Electronic Assemblies," which covers a lot of ground. The Technical Activi - ties Executive Committee (TAEC) says, among other things, that standards should focus on the end-use environment, not tell you how to make something. That last part is very impor - tant to remember because standards aren't the full recipe necessary to build electronics; they should be considered a guideline to reference when there is uncertainty on how to do some part of the process. The order of precedent on any drawing should be as agreed between the user and the supplier and standards like J-STD. This helps to drive home the point that IPC standards are not necessarily the final word on how to build a PCBA, but should be used as a companion to the demands of the customers. IPC Standards Process IPC standards are nearly ubiquitous these days on most all assemblies, which is a good thing. IPC standards are written, and con- stantly rewritten, by some of the best minds in the industry, and me. Seriously, they will let lit- erally anyone come to the task group meetings and have some input on what the next revi- sion should look like. 5-22A J-STD-001 is one of the largest task groups of the many focused ones, such as the 7-31B IPC-A-610 Task Group; it's one of the few meetings that lasts all day, including a review of how it plays with other standards on a different day. It's tied to train- ing, and there is another task group for J-STD on how to teach the class and what updates within J-STD-001 will impact that training. What I am getting at is that it's a big under- taking. One of the things I appreciate about the standards process within IPC is the fact that most are constantly being reviewed to react to changes within the electronics industry. This is of the utmost importance when you think about changes spurred by things like the required implementation of lead-free solder or trying to keep up with miniaturization. This requires reviewing and updating the assem- bly process that needs to be reflected in the standards, which is why it's so necessary to meet face-to-face during the year to make sure everything is being covered. The latest update to J-STD is a great exam- ple of how the standards are ever-evolving for the betterment of the industry. A cleanliness standard that was initially a military standard in the 1970s and then adopted by IPC was written into a lot of product drawing require - ments. This is the resistivity of solvent extract These electronics are most commonly found in industries like healthcare and aerospace. When your life, or the life of others, is on the line, Class I simply won't do.

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