09.03.2021 | Technical topic

Layout Tipps & Tricks

Layout Tipps & Tricks

Anbindung von SMT Bauteilen

General information about tests and testing possibilities

Ginzinger electronic systems offers different possibilities to comprehensively test the function of series-produced assemblies by means of functional and in-circuit tests.
test. For this purpose, the following points must be taken into account in the PCB design:

  •     Provide trap holes for the PCB (asymmetrical, typ. 3.2 mm, not plated through and not tinned.
  •     Test points in each electrical node. Through vias can be used as test points provided they have > 0.8 mm path diameter and are not covered.
  •     Distance of the test points to each other and to the PCB edge 2.54 mm. In exceptional cases and after consultation, the distance can be reduced to 1.27
        mm.
  •     Place test points evenly distributed on the PCB to balance the forces generated by e.g. contact needles.
  •     In the case of supply voltage networks, several test points should be placed. These should be distributed over the PCB or located at the beginning and end of
        the trace.
  •     and at the end of the trace.
  •     Preferably, test points should only be placed on the solder side.
  •     In the case of metrologically critical components (low-resistance shunts [test points]), a four-wire measurement should be provided.
  •     Components which have an enable input should be switched to "high" or "low" in the design via a pullup/pulldown. Thus there is
  •     This gives the possibility to deactivate them during the test.
  •     SMT and THR solder joints must not be used as test points, as they may be contaminated by flux residues. Contacting
  •     is then not possible.
  •     A test point diameter of 1 mm, but at least 0.8 mm is recommended.


Tips and tricks from 30 years of experience in electronics production can be found in our   EMS Design Guide.

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