Brazing Process for Joining Surfaces in Semiconductor Packaging Modules
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-08
This process provides a strong and corrosion-resistant bond suitable for affixing elements to ceramic substrates. In this process a good braze joint with very high strength is achieved by depositing a heavy nickel layer on the surface to be bonded, on the order of 10 mm, and a preform formed of silver-copper-indium braze alloy disposed between the surfaces and heated. During the heating step the braze alloy melts and consumes a portion of the nickel plating of the surface, forming a nickel-copper-indium intermetallic constituent. The nickel coating on the surface to be bonded must have a sufficient thickness so that a portion of the coating remains, forming a barrier to corrosion. The braze alloy has the following composition: Ag = 37 to 39% by weight Cu = 32 to 34% by weight In = 28 to 30% by weight.