US Patent 7269197 Controlling overspray coating in semiconductor devices

A manufacturing method, in which two device bars are bonded prior to facet coating to form a stacked bar pair. In one embodiment, each of the device bars has a p-side and an n-side, each side having a plurality of bonding pads, with at least some bonding pads located at the p-side of the first device bar adapted for mating with the corresponding bonding pads located at the p-side of the second device bar. Solder material deposited onto the p-side bonding pads adapted for mating is liquefied in a reflow oven, wherein surface tension of the liquefied solder self-aligns the device bars with respect to each other and keeps them in alignment until the solder is solidified to form a solder bond between the mated bonding pads. Two or more instances of the bonded bar pair are further stacked such that bonding pads located at the n-sides of adjacent bar pairs are mated in a relatively tight fit. The exposed facets in the resulting stack are then spray-coated with one or more reflective materials, with the solder bonds between the p-side bonding pads and the tight fit between the n-side bonding pads protecting those pads from overspray coating.