Metal working – Method of mechanical manufacture – Electrical device making
Patent
1994-03-25
1995-10-31
Arbes, Carl J.
Metal working
Method of mechanical manufacture
Electrical device making
29446, 29449, 295251, 174 163, 439 83, H01R 4316, H01B 734
Patent
active
054617740
ABSTRACT:
An electronic module assembly (10) is constructed by attaching semiconductor die (20, 22) to corresponding ceramic substrates (16, 18). A solder preform (14) is placed between the ceramic substrates and a base plate (12) which in turn is placed on a mounting fixture (26). Steel shims (28-42) are placed around the perimeter between the base plate and the mounting fixture surface. A restraining mechanism (24) passes through the center of the base plate and fastens to the mounting fixture to create a force on the base plate causing it to bow in an elastic manner. The assembly is reflow soldered and cooled with the module assembly restrained in the pre-bow apparatus. The elastic bow compensates for differences in thermal expansion and contraction characteristics between the ceramic substrates and base plate encountered during the reflow and later processes to prevent stresses from developing on the solder bond between materials.
REFERENCES:
patent: 4654966 (1987-04-01), Kohara et al.
patent: 4853828 (1989-08-01), Penn
patent: 5036584 (1991-08-01), Beauregard et al.
patent: 5146981 (1992-09-01), Samarov
Holmes Jeffrey G.
McNeil Andrew C.
Arbes Carl J.
Atkins Robert D.
Motorola Inc.
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