The View from Weiner

The use of chip-scale packages (CSPs) continues to grow, with an estimated 50 in development or in the early stages of manufacture and approximately 30 already in production at contract assemblers and OEMs.

CSPs seem to be proliferating-if not in format, at least in name-at what appears to be a geometric rate. The majority depend upon some form of BGA technology. Two billion units by the year 2,000 certainly seem more realistic as each month passes.

One of the newer entrants to the CSP arena is Advanced Semiconductor Engineering (ASE) in Taiwan. ASE became the 15th licensee for Tessera's mBGA® packaging technology and the first licensee in Taiwan. A few weeks later, ChipPAC in Korea unveiled its new automated mBGA assembly line in a full production mode.

Also noted this past quarter was Altera's announcement of its new "FineLine™ BGA package designed to put a 672-ball package in the same space as a 256-ball package.

Since I'm from the board side of the interconnect industry, I tend to think of infrastructure when thinking of CSPs. How will the interposers and substrates used in making the package be fabricated?

The primary imaging area for fine line circuits and mBGA packages provides fertile ground for investigation. Our first investigation of imaging equipment turned up a few surprises and several exciting new items:

We found a laser aligning automatic photoresist exposure system for precise circuit registration at Olec in California. The system produces lines and spaces down to 50 microns with conventional dry film photoresists.

We visited MRS Technology in Massachu-setts. MRS, the only U.S. flat panel display lithography vendor, disclosed that it is planning to shift its core business to focus on high density circuit interconnects. The company claims an ability to register layer-to-layer, or front-to-back on double-sided panels, of better than 5 microns (0.2 mils).

While returning from the CPCA and NEPCON shows in Shanghai, we met Floyd Horowitz (of California's Advanced Micro Systems) at an airport. He had just returned from Israel where he had acquired the distributorship from Creo of a new direct laser imaging system now being readied for introduction at the IPC Printed Circuits Expo.

During the same period, ETEC Systems, known as a supplier of e-beam patterning equipment for the worldwide semiconductor and electronics industries, entered the fray in April with the announcement of the shipment of its first production laser direct imaging system for the printed circuit board fabrication industry. ETEC's "beta" system was shipped to an undisclosed U.S. customer.

Laser direct imaging is expected to improve registration and critical dimension control. What remains to be seen is how versatile the machines are, what resists can be used with them, how they perform in a production environment and how cost effective they will be.

On the backend, Panasonic Factory Automation introduced (through its Create business unit) the CM-100, a multifunctional chip mounter that can handle BGAs and CSPs. It provides 100% ball inspection for ball pitch as fine as 0.5 mm and ball size as small as 0.35mm.

In Japan, experience with a variety of build-up and other high density flex and rigid substrates has led to a proliferation of technologies for creating thinner, lighter, higher density packages with microvias that seem capable of being a substrate for CSPs.

Mr. Weiner is Editor/Publisher of PAC/Asia Circuit News and a consultant to high technology companies. Contact him at 203.797.9103 or by fax at 203.797.9565. www.weiner-intl.com

By Gene Weiner
Contributing Editor