Flip-chip devices stress-dissipating adhesives

Lastly, adhesives are used to dissipate stresses that may be generated from thermal excursions, mechanical shock, vibration, or moisture. Specially formulated adhesives are effectively used as underfills for flip-chip devices and ball-grid-array packages to compensate for mismatches of expansion coefficients among the solder, the silicon chip, and the ceramic or plastic-laminate substrate. Low-stress adhesives are also used to attach fragile devices such glass diodes and to dampen stresses due to vibration. 

Underfill for flip-chip-attached devices. With the availability and increased use of flip-chip devices, a need has arisen to reinforce the connections and dissipate stresses resulting from mismatches in expansion coefficients among the solder, the substrate, and the device. This need has been met by underfilling the space between the solder connections with specially formulated underfill adhesives (Fig. 1.5). Underfill adhesives are... 

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