(July 26, 2010) — Henkel’s non-conductive paste (NCP) development will enable next-generation, high I/O fine-pitch technologies including new copper pillar (Cu Pillar) interconnects. Henkel’s Hysol FP5201 NCP offers the underfill protection required for Cu Pillar technology, effectively mitigating the stress between the substrate and the die.
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 40µm pitch, whereas traditional soldered flip chip pitches are generally in the range of 150 to 200µm.
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.
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.
“Working with a beta-site customer, Henkel’s top materials scientists embarked on a year-long development process to formulate an NCP that could meet some stringent performance demands,” said Henkel Senior Development Scientist, Donald 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°-300°C, little to no voiding and its outstanding reliability performance of MSL3, TCT1000 and HAST168.
Doug Dixon, Henkel Corporation, talks about Henkel’s new wafer backside coating technology for stacked die packages. In 2011, Henkel foresees a 5 um bondline thickness. Dixon also discusses copper pillar technology for chip stacking.
For more information, visit www.henkel.com/electronics