SEMICON WEST REPORT: Interconnect symposium heralds exciting year

By Fran&#231oise von Trapp, managing editor, Advanced Packaging

Participants in Tuesday’s Interconnect Symposium at SEMICON West, hosted by Kulicke & Soffa and Advanced Packaging magazine, shared insights into a list of trends, challenges, and opportunities in advanced packaging (e.g., wire-bonding and flip-chips) that are being thrust into the semiconductor manufacturing spotlight.

“This is one of the most exciting years in the industry with all the developments happening,” noted TechSearch International founder/president E. Jan Vardaman. “If you’re an advanced packaging engineer, you’re finally getting the recognition you deserve.”

Speaking to a packed audience, Vardaman led off with an analysis between wire-bonding and flip-chip trends. Advanced packaging accounted for 30% of the total packaging market in 2006, and will grow to 36.5% in 2010, according to Vardaman. “A lot of companies will tell you that their money is being made in advanced packaging,” she said.

The usual casts of characters — mobile phones, PDAs, and MP3 players — are driving the market, and the thin-is-in craze that started with Apple’s iPod is expected to continue with the iPhone, which reportedly sold more than 700,000 units in the first weekend. “There’s cool packaging inside this thing,” Vardaman noted, showing images of an iPhone teardown to identify many wire-bonded parts and a few wafer-level packages, including an Intel stacked-die package, and package-on-package (PoP) technology from Samsung consisting of a microprocessor in the bottom package with two stacked die in the top.

Stacked-die packaging reached 2.2 million units in 2006, and TechSearch expects that to hit 3.2 billion units in 2010. It has been demonstrated that 16 die can successfully be stacked, though 4-5 is more commonly seen, Vardaman noted, adding that most of these stacks are wire bonded and gold-stud bump bonded.

Looking ahead, Vardaman said that stacked package trends forecast thinner packages with higher levels of stacking and multifunctional chips. Challenges include wafer thinning and die attach, wire bonding, material selection, thermal performance, and business issues of logic and memory — the latter having driven PoP development. At least 10 major OEMS in handset and digital-still-camera markets have adopted PoP, due to the ability to use known-good-die (KDG). In 2006, 67 million PoPs shipped, and that number is expected to grow, Vardaman noted.

For IC packages, wire bonding contributes 124 billion units, or about 90% of the total available market. The remaining 10% are bumped die, though market penetration could increase to 14.9% by 2010, Vardaman suggested. Advanced packaging continues to grow in units and revenue, and 67% of all advanced packages are wire bonded — so why doesn’t flip-chip dominate? “We use what’s best suited to the technology at hand,” said Vardaman, explaining that flip-chip is used when needed for performance or for pad-limited designs. But because it’s more expensive (~30%) to build, “it’s used because you have to use it, not just for grins.” She noted that Intel has delayed major flip-chip adoption out to 2009, because wire bonding still produces viable products. And wire-bond technologies continue to advance, making the transition to flip-chip less critical. “Conventional technologies don’t stand still while novel technologies are developed,” Vardaman concluded.

Other Interconnect Symposium presenters included Stephen Lee, chief scientist at Freescale, who talked about the company’s bond-over-active (BOA) evolution and addressed the issue of metal lift failures; and Flynn Carson, STATS ChipPAC, who addressed advancements in stacked die packaging and interconnect schemes. Carson says we’re headed to increased density with through-silicon vias and 3D systems-on-chip, but that these processing developments are still a few years out. All levels of interconnection integrated together will support the next generation of highly functional cell phones, he added. Bob Chylak, Kulicke & Soffa, explained how to control pad structural damage for ultra-fine pitch copper wire. –F.v.T.

The SEMICON West Interconnect Symposium presentations will be available online at “


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