TMV: An ‘Enabling’ Technology for Next-Gen PoP Requirements
After years of R&D, testing and customer evaluations, Amkor's overmolded/laser ablation technology, a.k.a. through-mold via (TMV), is ready to meet next-generation package-on-package requirements.
Sally Cole Johnson, Contributing Editor -- Semiconductor International, 11/4/2008
Demand for package-on-package (PoP) is still rising, thanks in large part to wildly popular smartphones like Apple’s (Cupertino, Calif.) iPhone and Research In Motion’s (Waterloo, Canada) BlackBerry products. Recent teardowns of smartphones indicate that most major makers are relying on PoP to meet their digital processor and memory 3-D packaging requirements.
PoP technology is constantly evolving to address changing signal processing and memory architecture requirements, but also must overcome technical obstacles such as conventional solder ball interfaces and surface-mount technology stack processing in terms of next-generation high-density PoP requirements. In response, Amkor Technology Inc. (Chandler, Ariz.) has developed a forward-looking matrix mold laser ablation process to create through-mold via (TMV) solderable interconnects.
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| Through-mold via (TMV) technology is expected to provide size, thickness and warpage reductions, while enabling the higher interconnect density, performance and reliability desired for next-generation PoP applications. |
TMV bottom packages use matrix strip molding, which is standard in fine-pitch BGAs (FBGAs), to resolve warpage control and die-to-package density challenges found in today’s bottom PoPs. “After molding, a laser process ablates the mold compound in the locations where TMV interconnects are required,” said Lee Smith, Amkor’s vice president of laminate business development.
Benefits of TVM technology
Test vehicles and trials show TMV technology offers a much-coveted warpage control improvement, according to Smith, while also enabling a bottom package thickness reduction. “For PoP to continue as the 3-D architecture of choice, a new bottom package technology must deliver higher densities at a lower cost. Future bottom packages must support wirebond, stacked die, flip-chip and passive integration requirements in a smaller, thinner, flatter bottom package that can scale with BGA pitch reductions to 0.3 mm or below,” he added. “Overcoming the scaled interface bottleneck was the first major obstacle to overcome, and we believe we have achieved that with our TVM interconnect technology.”
As for TMV cost, Smith noted that it’s a very minor additional charge, less than ~10% above the standard bottom PoP. The cost adder “could be as low as even 5% if it provides a size reduction,” he added. “If you try to apply a standard PoP to next-generation requirements, it may not be capable of doing it, so it’s a minor cost vs. the current PoP technology. From a systems standpoint, it has minuscule impact. You’d probably pay more to try to push the current technology to higher current density limits.”
Looking forward, without an innovation in the stacked interface, a wide range of next-generation requirements would have stressed the infrastructure, Smith pointed out. “TVM technology allows us to leverage our global FBGA manufacturing and development capabilities to achieve low cost in high densities.”
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