Ask your placement engineers to program in an extra glue dot between the lead which always shorts, this will be a simple fixit.įigure 1: Here, the resist apertures are smaller than the pad size. As an alternative, when all else fails and when the design engineer does not want to change the design, use a glue dot. Sometimes it is not always possible to eliminate problems simply with changes to process parameters. Using a reduced resist aperture has been used in the past by the author to eliminate solder shorting. It is worth pointing out that during wave soldering the resist on the pad may affect the visual appearance of the joints but it will not cause any problems of reliability. The example in Figure 1 has been designed with resist apertures smaller than the pad size. PCBs in the ocean can cause a number of potentially serious problems. The mining industry can play a significant role in preventing further increases of PCB contamination in the ocean by eliminating or controlling PCBs. This clearance is necessary to allow for misalignment on the board during fabrication. The release of PCBs from mines can have important large-scale negative social and ecological impacts. ![]() ![]() The correct design rules for resist apertures are a 0.002-0.003" annulus ring around the pads. The resist on the board is directly related to the poor design rules used on this printed board. The solder joints shown in Figure 1 are satisfactory, but the solder resist on the pads has resulted in a reduction in the solder volume. Pad Contamination on a Printed Circuit Board
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