Invention Grant
US5641990A Laminated solder column 失效
层压锡柱

Laminated solder column
Abstract:
A method for forming solder balls and an apparatus and method for forming solder columns on the electrical contact pads of an electronic package in order to establish a more reliable electrical and mechanical connection between an electronic package and a printed circuit board. In one embodiment, solder balls are formed on the electrical contact pads of a package by placing solder cylinders over the electrical contact pads and then passing the package through a reflow furnace where the solder cylinders take the form of spheres and are wetted onto the pads. In a second embodiment, a laminated solder column is formed that is resistant to collapse during the manufacturing process. The laminated solder column comprises a solder cylinder being clad on its top and bottom surfaces with a solder material having a lower melting temperature than that of the center solder cylinder. When attaching the solder column to a package or a printed circuit board reflow temperatures are maintained above the melting temperature of the cladding material but below the melting temperature of the center solder cylinder such that the cladding is wetted onto the electrical contact pads of the package or printed circuit board while the center solder cylinder maintains its solid form.
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