Zymet, a supplier of adhesives and encapsulants, has introduced UA-3307-B, an edgebond adhesive to enhance board level reliability in automotive and other harsh environment applications. BGA’s whose corners and edges are bonded with this adhesive have passed more than 2000 cycles of –40°C to 125° C thermal cycling without failure. Large WLP’s, exceeding 8 mm in size, have passed more than 1500 cycles. The good results are attributable to the adhesives’ high Tg, 149°C, and low CTE, 15 ppm/°C.
The benefits of using the company’s edgebond adhesive, rather than introducing an underfill under the component, are significant. Board preheat and dwell time are not needed for underfill flow. There is no risk of underfill voids caused by flux residues impeding flow. And, there is no risk of underfill/flux-residue chemical incompatibility affecting underfill cure. The use of this adhesive is simple, repeatable, and reliable.
