METHOD AND ARRANGEMENT FOR THERMALLY RELIEVED PACKAGES WITH DIFFERENT SUBSTRATES

摘要

A method (80) of reducing stress between substrates of differing materials includes the steps of applying (82) solder (16) on a first substrate (14), reflowing (84) the solder on the first substrate to form a cladded substrate (30), applying (85) a medium such as flux or solder on a second substrate (42) having a substantially different coefficient of thermal expansion than the first substrate, placing (86) the cladded substrate on the second substrate, and reflowing (88) the cladded substrate and the second substrate such that thermal stress caused by the substantially different coefficient of thermal expansion between the first and second substrates is limited to when a temperature approximately reaches below a solidus temperature of the solder on the first substrate.