July - August 1999
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IC Packaging Foundries Are Taking the Lead in CSP Development
By Robert Crowley
Not long ago, semiconductor manufacturers followed Henry Ford's tradition and would sell you any color package you liked-as long as it was black.
Contract IC assemblers followed the lead of semiconductor companies and delivered black plastic packages to help semiconductor companies manage production volumes and decrease cost. The introduction of ball grid array packaging led to a leveling of the package development field, with both IC and assembly companies jumping into BGA development. Today, IC packaging foundries are beginning to take the lead in CSP development.
Several factors have contributed to this shift in packaging R&D. U.S. semiconductor companies started the transition when they moved package manufacturing overseas to reduce labor rates. Along with reductions in cost came reductions in package manufacturing expertise. Semiconductor companies focused more on front-end processes, and packages began to limit the ability of chips to meet customer demands. Meanwhile, advanced packaging technology moved from the realm of high-end computers and military electronics to consumer electronics.
Most semiconductor IC packaging foundries have developed fine-pitch BGA packages using laminate and polyimide interposers. Dozens of new package styles have been developed for specific applications. Much of this development work is happening at the assemblers.
In the United States, companies such as Amkor Technology and ChipPAC have invested heavily in CSP research and development. Amkor has developed the wsCSP for wafer-level processing, the Micro Leadframe package (MLP) for low-I/O chips, and the m2BGA laminate CSP for center-pad DRAMs. ChipPAC has developed the flip-chip-based FlashPAC and RamPAC packages for memory and the m2CSP for chip stacking, and is developing WaferCSP technology. Both of these companies, of course, have a strong Asian presence.
In Japan, the situation is a bit different. The vertically-integrated powerhouses continue to fund large packaging R&D groups.
Fujitsu has developed all types of CSP solutions, has commercialized at least five of these internally, and also offers contract assembly of their USON, BCC, and SuperCSP packages. NEC also makes several types of CSPs and has licensed its D2BGA to at least three assembly companies.
Large assemblers, such as Mitsui High-tec and Shinko Electric, offer a variety of CSPs, but have relied most heavily on conventional FBGA packages and technology licensed from other companies.
IC assemblers are well-suited to develop new packages. Many customers are fabless semiconductor companies that depend on silicon foundries for front-end processing and a packaging foundry for backend processing. These fabless companies depend on packaging foundry innovations to offer competitive packaging solutions for demanding applications.
Semiconductor companies also benefit from using packaging foundries. Instead of investing their own resources in packaging R&D, chip suppliers have access to new technology with a lower initial investment. Of course, the per-unit costs are higher in the beginning, but if a package proves successful, the option usually exists to license it from the packaging foundry and bring it in- house for high-volume, low-cost production. Chip companies can leverage their packaging budget by using packages that have been qualified at assembly companies and then ramping up the most critical packages internally.
Where does this leave independent package development companies such as FormFactor, ShellCase and Tessera? Tessera's business model has demon-strated the importance of licensing agreements with assemblers. The same leveraging argument applies in this case. Assemblers make the technology available to a larger number of users at a lower initial investment and create additional licensing opportunities for the package developers.
Packaging has become an equal part of the cost-performance equation in the silicon world, and packaging foundries have responded quicker than many semiconductor companies to the rapidly changing requirements of chip-scale packaging. This places the assemblers in a position to transfer new technology back to chip suppliers.
Mr. Crowley is president of Redpoint Research, a technology analysis and consulting company in the microelectronics packaging field. He can be reached at firstname.lastname@example.org.
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