Flip Chip Semiconductors Improved By Dow Corning Electronics

Dow Corning Electronics has introduced two new members of its family of lid-seal materials for flip-chip semiconductor packages. One offers a two-fold improvement in cure rate, and another is specifically formulated for the high temperatures that lead-free assemblies must endure during rework. The DOW CORNING EA-6800 and the EA- 6900 Microelectronic Adhesives follow the low voiding EA-6700 adhesive introduced last year. Both materials have been evaluated and qualified for production use by leading manufacturers, including Amkor Technology, Inc.

Lids, also referred to as heatspreaders, are integral to the production of flip-chip devices, a fast-growing segment of the IC packaging market. Lid-seal adhesives must withstand high humidity, temperature cycling and extreme operating conditions. These adhesives also must withstand higher processing temperatures associated with lead-free BGA attach and MSL testing, due to new Restriction of Use of Certain Hazardous Substances (RoHS) regulations. All of Dow Corning's lid-seal adhesives are RoHS compliant, and both the EA- 6800 and EA-6900 offer the excellent high-temperature performance that is necessary in processing lead-free assemblies. The EA-6900 Microelectronic Adhesive is particularly attractive for lead-free applications because it is specially formulated to withstand repeated exposures to the high processing temperatures associated with the rework of lead-free electronic components during board assembly.

As for the EA-6800, it is Dow Corning's first microelectronic adhesive formulated for fast curing. It cures in approximately 15 minutes, compared to the typical one hour required for other adhesives, with no loss of performance, thus offering better throughput and consequently lower cost.

"Our goal at Dow Corning is to have a complete product line to serve a variety of needs, and that's why we're expanding our offerings of Microelectronic Adhesives," said George Toskey, electronics assembly marketing manager for Dow Corning. "We're focusing on customer needs and requests, and that's what drove the development of the EA-6800 and the EA-6900."

Both the EA-6800 and the EA-6900 are available now in production quantities. Like Dow Corning's other adhesive offerings, both have been thoroughly tested at customer sites. The EA-6800 has been evaluated and accepted by a leading chip manufacturer and the EA-6900 has been qualified by Amkor Technology.

Based on proprietary technology, like their predecessors, the EA-6800 and the EA-6900 adhesive formulas feature reduced voiding from residual moisture within substrates, which leads to improved adhesion to ceramic and organic substrates. The adhesives also maintain a low modulus, a key quality that allows both to absorb thermomechancial stress when used between two materials (such as laminate substrates and nickel-plated copper lids) with differing thermal expansion coefficients. These features make the EA-6800 and the EA- 6900 ideal for high-performance devices that employ flip-chip technology.

Flip-chip is one of the high-growth technologies in semiconductor packaging. It is an increasingly popular technique in which the chip is placed face down and its bond pads directly connected to the substrate with metal studs or solder, thereby eliminating wire-bonding. The market for flip-chip applications is poised to expand from 785 million units in 2006 to 1.74 billion units in 2011, according to market research firm Prismark.

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