Henkel's non-conductive paste (NCP) solutions have long enjoyed a leading market position for traditional Gold - Gold flip chip processes. Recent NCP innovations from the global materials leader are also now enabling next-generation, high I/O fine-pitch technologies including new copper pillar (Cu Pillar) interconnects.
Driven by the need to increase functionality while simultaneously maintaining or decreasing device footprints, Cu Pillar technology offers a structure conducive to such demands. The architecture of Cu Pillar, as compared to conventional solder bumps or solder balls, is forgiving of much finer pitches and, therefore, allows higher I/O counts per die. With Cu Pillar, for example, a die can accommodate 40um pitch, whereas traditional soldered flip chip pitches are generally in the range of 150um to 200um.
Henkel's Hysol FP5201 NCP offers the underfill protection required for Cu Pillar technology, effectively mitigating the stress between the substrate and the die. The tighter pitches of Cu Pillar interconnect technology are not highly compatible with traditional capillary underfill processes, as flow time can be a drain on throughput and UPH and complete coverage is uncertain at best. Hysol FP5201 resolves these issues; the material is applied to the substrate prior to die placement and thermal compression, providing more robust coverage and improved device protection.
In addition to these advantages, Hysol FP5201 is also compatible with overmolding, which is an emerging requirement for some advanced Cu Pillar processes. Not only does the material have to provide a physically reliable and stable bonded package, it must also maintain its integrity and reliability following the molding process. This, in fact, was one of the more challenging aspects of the development process as older-generation NCPs have been unable to deliver robust post-molding performance.
Henkel Senior Development Scientist, Donald Frye, explains the demanding requirements for Hysol FP5201: "Working with a beta-site customer, our top materials scientists embarked on a year-long development process to formulate an NCP that could meet some stringent performance demands," says Frye. "The new material had to cure very quickly to accommodate a very fast bonding process, provide a high level of reliability and be compatible with the overmolding process - all in a high volume production environment. In each instance, Hysol FP5201 was able to deliver."
Other benefits of Hysol FP5201 include its fast cure of between one and four seconds at a bonding temperature range of 220°C - 300°C, little to no voiding and its outstanding reliability performance of MSL3, TCT1000 and HAST168.
"The development of Hysol FP5201 is a very significant material innovation," concludes Frye. "Without it, the advance of robust, high-volume, fine-pitch Cu Pillar processes for microelectronics would be impractical. This material improves throughput through lower cure times, enhances package reliability and allows for exponentially greater I/O counts and finer pitches."
For more information on Henkel's Hysol FP5201, call 949-789-2500 or log onto henkel.com/electroncis.
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