Low Stress Braze
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
The present low stress braze reduces the stress resulting from the differential thermal expansion of the braze and a multilevel ceramic (MLC) substrate. The low stress braze is formed by alloying a conventional Au-20%Sn braze with one or more of the following low-stress alloying elements: Zr, Nb, Bi, or Pb. These alloying elements modify the thermal expansion coefficient and/or modulus of the braze. The melting point and fracture strength determine the amount and mix of alloying additions. By limiting the thickness of the braze, the tendency of thermal stresses to fracture the braze joint is reduced. It is preferred that the braze thickness be between about 5000 Angstroms and 10 m depending on the surface roughness and stress distribution.