Section: DESIGN

Components

Austin, Texas -- Flexible circuits may be a tiny segment of the overall circuit-board market, but the technology is making huge strides forward, according to a new report from TechSearch International. As flex circuits find their way into a host of new products, adhesiveless solutions are coming on strong and line widths are beginning to shrink, to 100 microns and below.

"I was frankly amazed at all the activity; there's a lot of implementation," said Jan Vardaman, president of TechSearch. "The growth in the market was staggering." Indeed, the report, "Flexible Circuits: Worldwide Production Analysis," suggests that production levels are soaring (see chart).

Just because flex circuits are a tiny portion of the total circuit-board production doesn't mean the technology isn't robust. The authors found that there is plenty of activity in flex circuits, which have been around long enough to have built up an infrastructure. Much of the market is in Japan.

"Japan is the largest manufacturing region, with 60 percent of a $2 billion market in 1995," said Tom Goodman, senior analyst at TechSearch. "That's partly because they have manufactured very, very cost-conscious flex boards that go into cost-sensitive consumer products like cameras, and partly because there is a lot of competition there. MITI [the Ministry of International Trade and Industry]lists 33 manufacturers that have over $1 million in flex sales."

The interplay between end markets and production capabilities is highlighted by the difference in board types produced in Japan and the United States.

"Japan typically manufactures simpler circuits--single-or double-sided boards--though there are companies that are making very complicated circuitry," Goodman said. "In the United States, the history offlex is for military applications and avionics, which tend to be very complicated products. There are [U.S.] companies doing high volumes of flex, but it's in automotive, not consumer."

The basic substrate is common throughout the world, with around 85 percent of flex boards using polyimides, Goodman said. But the remainder of the technology is going through some changes.

"A technology that is becoming more popular is adhesive-less, which differs from today's techniques," said Goodman. The latter use adhesives to at-tach copper to polyimide. The adhesiveless approach is "becoming popular in the U.S. because it gives you finer lines. Another change is that people are going away from the punched overlays that are used to protect the circuit. They're going to photoimageable technology, which is geared to finer lines."

Those line widths are beginning to shrink, though their implementation is occurring slowly. "The majority of production is still in the 125- to 150-micron-and-greater range," Goodman said. "The Japanese are starting to push down to 75 microns. A number of U.S. companies are doing 100 microns, and some are doing 50. Some of them are sampling 25-micron lines. I'm not sure how useful those are for production,but the technology is there."

The TechSearch report split its examination into four geographical segments: Japan, the rest of Asia, Europe and the United States. The U.S. market has been undergoing an interesting change since the end of the Cold War, according to TechSearch: Domestic providers are now free to compete with technologies that were developed for the military.

The markets in Europe and Asia are smaller than the other two. In Europe, much of the flex production is targeted toward specific applications, such as watches. In Asia, as in Japan, much of the technology is aimed at consumer products.

The report examines flexible circuits from a variety of standpoints, from market drivers to technical and business issues. The common thread is production technology, which is affected by all the other issues.

GRAPH: FLEX-CIRCUIT PRODUCTION PROJECTED TO CLIMB

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By TERRY COSTLOW