Abstract: A solder preform has gaps extending from the boundary of preform towards the preform center. During reflow soldering, the gaps close from the center towards the boundary. This allows flux and gasses to escape the interface between the solder and the substrate. Particularly, flux accumulates in the spaces formed by the gaps and is forced to the edge of the solder preform as the gap closes. In further embodiments, channels are formed on one or both surfaces of the solder preform. In addition to further assisting in the escape of gas and flux during reflow, the channels and gaps increase the effectiveness of oxygen purging using inert or reducing gasses in the reflow chamber. Additionally, the channels and gaps increase the effectiveness of vacuum solder.

Abstract: A solder preform has gaps extending from the boundary of preform towards the preform center. During reflow soldering, the gaps close from the center towards the boundary. This allows flux and gasses to escape the interface between the solder and the substrate. Particularly, flux accumulates in the spaces formed by the gaps and is forced to the edge of the solder preform as the gap closes. In further embodiments, channels are formed on one or both surfaces of the solder preform. In addition to further assisting in the escape of gas and flux during reflow, the channels and gaps increase the effectiveness of oxygen purging using inert or reducing gasses in the reflow chamber. Additionally, the channels and gaps increase the effectiveness of vacuum solder.

Abstract: This invention contemplates an apparatus for affixing to a papermaking felt a plurality of beads comprising means for supporting a papermaking felt having a working surface and means for applying beads of plastic backing, said beads extending away from said working surface and having top portions which are spaced from each other along said working surface to form channels for liquid flow.