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58 PCB007 MAGAZINE I APRIL 2018 imum rated voltage is a statement in this case. However, item 2 is significant because it ex- pressly calls out the IPC-6012D amendment specific to space and military avionics. That specification has a specific ET requirement for 250V. See what I did there? Okay, now is where it can be a little tricky. What if our example is a standard build to IPC- 6012 and the statement "maximum rated volt- age = 40V" is observed? What should the PCB be tested to? In this case, referring to IPC-9252, if the rated voltage is specified rather than a test voltage on the master drawing, the rated voltage shall be used or 40 volts minimum, whichever is greater. So in this case the 40V is correct. Another statement that can be seen as brief- ly noted in the above example is "test volt- age = XX." Now in this case, the statement is significant as we are being told specifical- ly what the test voltage shall be. However, what if the test voltage stated is less than 40V? Houston, we have a problem. With automated test equipment, to be compliant to IPC-9252, MIL-PRF-31032, MIL-PRF-50884 and MIL- PRF-55110, a minimum voltage of 40V must be used. In fact, in the case of IPC-6012D(DS) the minimum is 250V! But what if there is a statement on the mas- ter drawing of "maximum rated voltage = 24V" and the Certificate of Compliance states the test voltage was 100V? I know, you just thought the CoC should state 40V? Not neces- sarily true. Remember the specifications state a minimum of 40V shall be used. Testing the PWB at 100V is completely valid. To summarize: 1. Maximum rated voltage shall be used to test the PWB if it is 40V or greater. Otherwise a 40V minimum default is to be assumed. 2. Test voltage shall be used if it is 40V or greater and needs to be IPC/MIL-compliant. A test voltage statement of less than 40V needs to be clarified by the customer; if used it will not be military/IPC-compliant. 3. If neither a maximum rated voltage or test voltage is stated, a minimum of 40V shall be used. Higher voltages are acceptable. 4. If a maximum rated voltage is stated as less than 40V, a minimum of 40V shall be used. Voltages above that minimum used are valid for the certificate of compliance. See you next month! PCB007 Todd Kolmodin is the vice president of quality for Gardien Services USA, and an expert in electrical test and reliability issues. To read past columns, or to contact Kolmodin, click here. The MIPI Alliance, an international organization that develops interface specifications for mobile and mobile- influenced industries, recently formed the MIPI Automo- tive Working Group (AWG) to ad- dress the needs of the automo- tive ecosystem. As the number of sensors continues to increase in the automobile to support pas- sive and active safety, infotain- ment, advanced driver assistance systems (ADAS) and autonomous driving systems, the need for in- terface specifications is apparent. The group will collaborate with other MIPI working groups on an automotive physical lay- er specification for longer reach applications. "The approval of the MIPI Automotive Working Group marks a significant milestone for MIPI Alliance's development activ - ity," said Joel Huloux, chairman of MIPI Alliance. "While MIPI's focus is foremost on developing interface specifications for mobile devices, automakers already rely on MIPI's industry-standard interfaces. This additional focus on automotive is a natural extension to broaden MIPI specifications' applicability." MIPI Alliance Expands Reach with New Automotive Working Group

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