New Leadframe-Based Package Integrates QFN, TQFP Technologies
Sally Cole Johnson, Contributing Editor -- Semiconductor International, 2/6/2008
Amkor (Chandler, Ariz.) recently debuted “FusionQuad,” a leadframe-based plastic packaging technology platform that fuses quad flat pack no leads (QFN) and thin quad flat pack (TQFP) technologies. Interestingly, this approach eliminates the historical pin count barrier of peripheral leaded configurations and can double the number of external I/Os of classic leadframe packaging to nearly 400 unique pins — while also delivering a 50% reduction in package size for a given lead count. Its basic outline combines standard peripheral leads with the option of one or two rows of inner lands.
As far as market drivers, there is tremendous ongoing interest and investment in developing highly miniaturized packages to scale with die-size shrinks. While there’s lots of activity going on in other parts of the market (wafer-level flip-chip, chip-scale packaging and 3-D packaging), Amkor noticed that 100- to 400-pin range of standard packaging wasn’t being particularly well served and decided to do something about it.
The result? A new approach to leadframe-based packaging that’s a bit different. “We achieved a breakthrough in package performance and price through the novel integration of inner lands on an exposed pad TQFP-style package,” explained Tim Olson, Amkor’s senior vice president of system-in-a-package (SiP) and leadframe products. “As die sizes shrink with each new wafer node, the wire lengths become a concern in a TQFP — causing signal integrity limitations. Inner lands enable shorter wire lengths, offering improved high-speed or RF circuit performance up to 10 GHz. We also designed FusionQuad with the inner lands separated laterally from the peripheral leads to provide space for low-cost PCB through vias. Low-cost boards are essential to a wide range of consumer applications.”
As you can see in the cross-section of FusionQuad, the package has a thickness of 0.8 mm, and its short signal paths to the bottom lands translates into high-power dissipation capability with the solderable exposed die attach paddle.
Because the package is a bit different, some people are wondering if it will work, Olson acknowledged. “The answer is yes,” he said. We’ve already done the package-level reliability testing and conducted board-level engineering studies, and it’s all been very favorable.”
A cross-section of FusionQuad, shown with dual rows of inner lands (0.8 mm thick). For a larger version of this image,  . Courtesy of Amkor.
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Designers can now take full advantage of new system-on-a-chip (SOC) devices without having to migrate from a QFP to a ball grid array (BGA), a more costly solution, according to Lee Smith, Amkor’s senior director of business development. “We introduced FusionQuad at a recent JEDEC meeting for standardization under the QFP family, and are in the process of publishing the application notes for surface-mount assembly with a leading EMS supplier. We plan to enable further infrastructure development by offering mechanical examples through third-party distributors,” Smith added.
FusionQuad was designed for applications demanding superior electrical or thermal performance in a budget-conscious environment, and is expected to find applications in products such as hard disk drives, laptops, Ethernet communication, digital TV and data conversion, set-top boxes and other consumer electronics devices.
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