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A novel polymer technology for underfill

Published online by Cambridge University Press:  30 July 2012

Osamu Suzuki ,
Toshiyuki Sato ,
Paul Czubarow  and
David Son
Osamu Suzuki
Affiliation:
Namics Corporation, 3993 Nigorikawa, Kita-ku, Niigata-City 950-3131, Japan, E-mail os@namics.co.jp, TEL +81-25-278-6600
Toshiyuki Sato
Affiliation:
Namics Corporation, 3993 Nigorikawa, Kita-ku, Niigata-City 950-3131, Japan, E-mail os@namics.co.jp, TEL +81-25-278-6600
Paul Czubarow*
Affiliation:
eM-TECH, Inc.,
David Son
Affiliation:
Department of Chemistry, Southern Methodist University, Dallas, Texas
*
*Email: paul@em-tech.us
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Abstract

Capillary type underfill is still the mainstream underfill for mass production flip chip applications. Flip chip packages are migrating to ultra low-k, Pb-free, 3D and fine pitch packages. Underfill selection is becoming more critical. This paper discusses the performance and potential of underfills using a novel organic-inorganic hybrid polymer technology.

Compared to eutectic and high lead solder, tin-silver-copper solder has lower C.T.E., higher elasticity and greater brittleness. In light of these properties, it is generally better to select high Tg and lower CTE underfill in order to prevent bump fatigue during reliability testing. Given the brittleness of low-k dielectric layers of flip chips, the destruction of low-k layers by stress inside the flip chip packages has become a major issue. Underfills for low-k packages should have low stress, and the warpage should be small. It is expected that as the low-k trend expands, the underfill is required to provide less stress. Low Tg underfill shows lower warpage. New chemical technologies have been developed to address the needs of underfills for low-k/Pb-free flip chip packages, specifically organic-inorganic hybrid polymer compounds. The organic-inorganic hybrid polymer provides excellent cure properties which enable a balanced combination of low stress and good bump protection. The material properties of the underfill were characterized using Differential Scanning Calorimetry (DSC), Thermo-Mechanical Analysis (TMA), and Dynamic Mechanical Analysis (DMA). A daisy-chained test vehicle was used for reliability testing. A detailed study is presented on the underfill properties, reliability data, as well as finite element modeling results.

Keywords

chemical compositionelectronic materialjoining
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1428: Symposium C – “Interconnect Challenges for CMOS Technology--Materials, Processes and Reliability for Downscaling, Packaging and 3D Stacking” , 2012 , mrss12-1428-c07-01
Copyright
Copyright © Materials Research Society 2012

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References

1. Chen, K. M. et al. , “Effects of Underfill Materials on the Reliability of Low-k Flip Chip Packaging,” Microelectronics Reliability, Vol. 46, No. 1, 2006, pp.155–163.Google Scholar
2. Paquet, Marie-Claude. et al. ,, “Underfill Selection Strategy for Pb-Free, Low-K and Fine Pitch Organic Flip Chip Applications,” Proc Electronic Components and Technology Conf, 2006, pp. 1595–1603.Google Scholar
3. Schmaltz, Brian et al. , “Underfill Design for Low-k Dielectrics & Lead Free Application,” Proc IMAPS International Conference and Exhibition on Device Packaging, Scottsdale/Fountain Hills, AZ, Mar. 2010.Google Scholar