As an OEM, we have recently had a customer impose on us
          MIL-STD-1547.  That document requires we test a minimum of
          three SMT lands per IPC-TM-650, Method 2.4.21 after
          subjecting the samples to 5 soldering and 4 desoldering
          cycles.  The land shall withstand 500 psi of vertical pull.

          The product we are designing/procuring has standard chip cap
          components, as well as some .020 inch quad packs.  The PWB
          laminate is polyimide.  We procure a lot of polyimide PWBs,
          most of which have surface mount components.  We have never
          had a problem with respect to lifted or peeling SMT lands.

          As this is a test we've never imposed on our PWB suppliers,
          my questions include:
          1) Is the test valuable?  What does it demonstrate?
          2) Is the 500 psi pull limit reasonable? For all pad sizes?
          3) Would results be more or less favorable on FR4 laminates?
          4) How frequently should this be tested?  (I know
          what IPC-RB276 - 2 times per month for class 3 - but
          wouldn't it be primarily laminate lot dependant?)

          My company won't mind spending the extra money on testing
          if there is a benefit in doing so.  But, I'm not clear on
          the added benefit this test will provide.

          Thank you for any insights.

          Andy Pedersen
          Harris Corp.
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