Siemens Aktiengesellschaft Berlin & Munchen

Siemens-albis, Ag

Robert Furrer

Imre Bajka

During the pre-soldering or tinning 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 apparatus 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 serves to guide the printed circuit board essentially horizontally in a frame and to accelerate 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.

Apparatus for removing solder from the drill holes of empty printed

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.

Method for removing solder from the drill holes of empty printed circuit

The solder applying apparatus enables applying solder to both sides or faces of printed-circuit boards travelling essentially in horizontal direction through a production or manufacturing line, and which circuit boards are not yet equipped with electrical components or the like. The apparatus contains a solder applicator means or device where liquid solder is pumped from a supply container in such a quantity that a solder wave forms over an outlet or discharge opening of the applicator device. This solder wave extends beyond the feed or transport plane of the printed-circuit boards. At the side walls of the applicator solder device there are mounted guide elements formed of metal plating or sheet metal which extend beneath the feed plane, the solder flowing-off by means of such guide elements. The angle of inclination of the metal guide elements is adjustable with respect to the feed plane. Also the spacing between the discharge opening of the applicator solder device and the feed plane is variable. Directly above or below, as the case may be, the feed plane there are arranged substantially cylindrical-shaped elements at the inlet side and the outlet side where the printed-circuit boards respectively inbound and outbound from the solder applying apparatus. These cylindrical-shaped elements are disposed at the regions of the ends of the guide elements and extend transversely with respect to the direction of feed or advance of the printed-circuit boards. These cylindrical-shaped elements function, on the one hand, as solder strippers or scrapers and, on the other hand, as limiting means for the solder blanket which during the through-passage of a printed-circuit board tends to spread-out at the upper surface or face thereof.

Growing community of inventors

Zurich, Switzerland

Robert Furrer