Controlled Solder Dam Structure by Special Evaporation-Gun Design
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
A method is described to control terminal design and wettable area of braze/solder for a multilayer ceramic substrate pin braze joint. A schematic cross-section is shown in Fig. 2. Pin 15 is attached to a multilayer terminal pad 13 on the multilayer ceramic substrate 6 by a braze 8. The braze is restricted to the central region of the terminal pad since the periphery of the pad is not wettable by braze. This particular structure is fabricated in an evaporator by positioning the evaporation sources such that the evaporant will automatically create a wetting barrier at the terminal pad edges. Referring to Fig. 1, the solder (or braze) dam can be obtained by placing the Au source at the center line of the evaporation dome and the other sources Ti (or Cr) 2 and Cu 3 off-center.