Wave Soldering Defects


Outgassing on a Printed Circuit Board

Outgassing is still a common problem associated with wave and hand soldering. Basically when a board is soldered any moisture in the board close to the hole is heated and turned to vapor. If there is thin plating or voids in the plating, gassing can come through the plated hole wall. If solder is present in the hole, this will produce voids in the solder as it solidifies. The voids may appear as small holes in the surface of the joint, as shown in Figure 1, or much larger cavities.

Having the correct copper plating thickness in the through holes is the key. A minimum of 25┬Ám of copper should be present on the surface of the hole walls.


Figure 1: Voids caused by outgassing
Figure 1: Voids caused by outgassing.


Most Common Reasons or Solutions:

  • Poor pre heat process when using VOC free fluxes leads to spitting of very fine solder balls.
  • This plating of less that 20um in the through hole or where the surface of the hole is so poor the plating does not cover broken glass bundles leading to gassing.
  • In the old days you could have outgassing from the plating on pins but not to the degree shown.
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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.

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  • Epec Founded in 1952
  • IPC Founded in 1957
  • Epec Builds PCB for Apollo 11