Wave Soldering Defects


Solder Mask Discoloration on a Printed Circuit Board

Normally this is a cosmetic issue but should be investigated for the real cause. When running a thicker board it is probable that the soldering process or dwell times may have changed.


Figure 1: Dark stripes on the solder mask after selective soldering
Figure 1: Dark stripes on the solder mask after selective soldering.


The most common reasons for this occurrence include:

  • Different flux used, higher temperature, longer dwell time or boards were run twice in pallet
  • Solder mask/resist type, thickness or cure cycles have changed
  • PCB supplier has been changed, or mixed batches of boards

There is no reference to the board finish, solder alloy being used or flux type - water or alcohol based. These are important when conducting analysis of the process problem.

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Our History

As the oldest production Printed Circuit Board Company in North America, perhaps in the world, the 60-year plus story of Epec is connected to the development of the PCB and the electronics industry.

From pioneering innovation in the PCB Industry with R & D, training and setting professional core values, the legacy of Epec has now passed to a new generation of very bright young people, but still continues the great tradition of imagination.

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  • Epec Founded in 192
  • IPC Founded in 1957