An Independent Journal Dedicated to the Advancement of Chip - Scale Electronics January - February 2000 Email the editor

Trends in Adhesives for Advanced Electronics Packaging

Current trends in microelectronics packaging-such as size and pitch reductions, cost reductions, and new materials-will have a direct impact on adhesive development for the electronic packaging industry. In the next century, the electronics packaging industry will challenge adhesive manufacturers in two areas that have traditionally been 3M strengths: materials and process development.
	Dr. Harry Andrews	Harold J. Wiens

Materials

In the coming years, adhesive manufacturers will be asked to continue to produce cleaner, faster curing and more reliable materials.

Adhesive purity will be increasingly important for fine pitch electronics packaging. Control of ionic contamination on surfaces and in adhesive formulations is critical to prevent corrosion. As the distance between traces decreases, the probability for electromigration increases. Therefore, providing ionically clean adhesive materials will be even more important.

Reliability will continue to be a primary concern. Finer ball pitch packages will be more sensitive to solder joint fatigue failure. Low stress adhesives will be needed to alleviate this. Adhesives must also be resistant to moisture induced delamination during reßow. The move toward higher temperature lead-free solders will make this requirement even more difficult to satisfy in the future.

Process Development

Already, adhesive manufacturers are being asked to work more closely with manufacturers to develop new processes for the application of adhesives.

A key component in the usefulness of a particular adhesive chemistry is manufacturability. Robust processes for the application of the adhesive are critical. Processes must be identified to economically pattern, register, laminate and cure these materials. Packaging adhesives will be pushed to faster cure speeds to accommodate higher throughput manufacturing. Catalyst and cure systems with good shelf stability and fast cure at moderate temperatures will be needed. Curing methods other than thermal, such as irradiation, may be employed to improve throughput rates. Laser patterned or photo-imageable materials will be more prevalent in the future to eliminate expensive tooling and to meet tighter registration tolerances.

With the right combination of materials and process development, adhesive manufacturers will be ready to meet the challenges in the electronics industry far into the next century.-Dr. Harry C. Andrews, Executive Vice President, 3M Electronics and Communications Markets and Harold J. Wiens, Executive Vice President 3M Industrial Markets

3M manufactures a wide variety of products for the electronics industry, including adhesives, fluorinated gases and liquids, wafer tapes, static control products, EMI shielding, carrier tapes, trays, sockets, cables and connectors, and flexible circuits.[.3M.com/US/electronics_mfg/]