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