| 摘要 |
During the pre-soldering of printed circuit boards, as a rule, also the drill holes or bores and, in particular, the through-metallized drill holes are filled in an undesirable manner with solder. This solder must be removed before mounting the electrical components or elements upon the printed circuit boards. A simple method is disclosed for this purpose, affording a faultless de-soldering of the drill holes, without deleteriously affecting the properties of the solder material. The printed circuit boards, in a condition where the solder applied during the pre-soldering operation is still molten, are accelerated at least once and thereafter suddenly brought to standstill in such a fashion that the excess solder is knocked or propelled out of the drill holes. The apparatus for accomplishing the method contemplates guiding the printed circuit board essentially horizontally in a frame and accelerating such printed circuit board in a guided vertical drop or fall in the direction of an impact location, so that upon concussion of the frame at the impact location the excess solder is downwardly knocked or propelled out. |
