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Incomplete Joint
The incomplete solder fillet is often seen on single sided boards after wave soldering. In the example the lead to hole ratio is excessive which has made soldering difficult. There is also evidence of resin smear on the edge of the pad. It may be possible even on this design to improve the soldering performance by decreasing the conveyor angle from 6-4o. This reduces the drainage performance of the wave but can lead to the incidence of shorting. Reducing wave temperature has also been seen to overcome the problem. As a guide the hole to lead ratio is normally the lead diameter plus 0.010" which is the normal guideline for automatic insertion.