Repairing a PCB with a defective BGA, uBGA, or QFN is often a difficult and tedious task. The conventional method is to remove the defective device from the PCB; clean the pads on the PCB, then print solder paste on the pads with a mini-stencil. The stencil footprint needs to be small enough to fit into the area of the removed part, which is normally surrounded by other devices in close proximity. This paper will describe an alternative repair method. Instead of printing solder paste on the PCB pads this system prints solder paste directly on the QFN pad or the BGA solder balls. The repair tool is simple and easy to operate. A package can be inserted in the tool, printed and placed on the PCB in about 30 seconds. The tool is made up of two components: a universal master tool, which can be reused for all packages and a unique component, which is designed for a specific package. The unique components consist of a stencil and a device holding fixture. Both are free standing metal foils with laser cut or electroformed apertures.
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