Normally during wave soldering of single-sided boards the solder on the pads of holes without a lead can still be covered with a solder skin. Such a skin makes it impossible to directly mount leaded components after a wave soldering process in such holes, since they can be covered by a skin of solder.
If leaded components must be mounted after a wave soldering process it is important that the holes in which these components must be mounted are kept open. Only in this way the component can be directly mounted and soldered afterwards.
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