What should be noted concerning cleaning of misprints?

There are different cleaning requirements for bare board vs. single side mounted misprints.

A misprint is a printed circuit board side which is faulty printed with solder paste or adhesive or is declared as faulty for other reasons. The cleaning of a printed bare circuit board is subject to the requirements similar to stencil cleaning. The cleaning time is approx. the same as for a stencil and can be carried out quickly and easily after testing and approval in a qualified process using a stencil cleaning system.

However, if one side of the misprint is already loaded with active components which are already soldered, it is subject to the cleaning requirements of an assembled circuit board. Paste or adhesive of the misprinted side could still be cleaned in a "misprint cleaning time". The backside assembly would, however, in this time only be partially cleaned, i.e. the soldered flux / rosin would not be completely removed from the components. In this case, the partially cleaned respectively cracked flux could lead to product errors.

For this reason, the cleaning time for the misprint on a circuit board that has already been mounted on one side is approximately the same as in the case of a finished, correct assembly. It is generally carried out with a special PCB cleaning detergent and with a two-stage water, DI / DM water rinse process in a qualified PCB cleaning system. The drying of the assembly is also more complex than that of a bare board misprint due to the scoops and intermediate spaces and therefore also requires suitable drying.


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