Surface mount package seam welder apparatus and method

Abstract

A seam welder for sealing a cover of a surface mount package to its carrier includes a table for receiving a fixture which itself carried surface mount packages to be welded for sealing an electronic component therein. Electrical current to welding electrodes is controlled for resistance welding the cover to the carrier. Electrode temperature and table temperature and monitored. Heat exchangers including a reservoir and heat transfer fluid interface with the electrodes and the table for controlling their respective temperatures and thus the temperature of the fixture and package during the welding of the cover to the carrier. Factors affecting the quality of the weld, including temperature, time/temperature profile, the temperature of the electrode just before current starts to flow, the temperature of the package/cover and carrier combination just before current starts to flow, the difference between the package/cover and carrier combination temperature and the electrode temperature just before current starts to flow, are monitored and controlled. As a result of such monitoring and control, induced stresses typically resulting in a package because of the differing coefficients of thermal expansion for the materials used in the package are reduced during and after sealing the cover to the carrier. Seal quality and integrity is improved and the range of seal parameter tolerances tightened.