In a single blow, Weymouth based specialist Tecan Components has solved a range of problems associated with the automated soldering of RFI screening cans/fences onto PCBs - with the introduction of the “Plimsoll line and lattice bridging stencils”.

Traditionally, PCB assemblers experience soldering consistency problems while simultaneously reflowing RFI cans and other surface-mount components. The solder migrates up the sides of the cans, crucially drawing it away from the solder tracks where it should ultimately reside, resulting in blow holes and poor joints.

Down-the-line, it is then necessary to embark on expensive re-work action to ensure a good joint with the necessary electromechanical integrity is achieved. Because of these problems, some PCB assemblers will not put cans/fences through the reflow process at all, soldering them as a separate time-consuming off-line operation.

Overcoming all these problems, Tecan has developed a technique which introduces a linear break in the plating, all the way around the walls of the screening can, so that solder can only flow up the wall of the can to a set height, that defined by the “Plimsoll line”. Solder will not “wick” higher than this and therefore remains where it should be - on the pad to ensure a good joint. To further enhance this, the solder paste stencil itself has a “lattice bridge” printed between sections of the track, effectively encouraging solder to flow into an even seam.

The two-part technique is exceptionally effective, producing highly repeatable and consistent seam joints, without subsequent rework or separate assembly operations.

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