In microelectronics assembly, adhesives are most often used to bond dissimilar materials with mismatched coefficients of thermal expansion. As a consequence, the bonded parts bend at temperatures above and below the adhesive curing temperature, resulting in stress on the active device. Zymet’s Ultra-Low Stress Adhesives, by absorbing the bending stress, are uniquely suited for bonding of stress sensitive devices such as piezoelectric and micro-machined sensors, CCD image sensors, and integrated optoelectronic devices.
A test was performed to compare the performance
of a conventional die attach adhesive with an Ultra-Low
Stress Adhesive. A 250 x 250 mil silicon die was
bonded to a copper leadframe. Both adhesives were
cured at 150ºC. Die curvature was measured at room
temperature. The conventional adhesive yielded a
radius of curvature of 1000 mm. The Ultra-Low Stress
Adhesive yielded a radius of curvature of 100,000
mm.
