Teck-Gyu Kang

Wide area vertical expansion (WAVE/sup TM/) package design for high speed application: reliability and performance

A two metal flex-based WAVE package has been developed to replace four metal rigid based PBGA package. High board-level reliability was the primary motivation for this project and an equivalent electrical performance was a challenging target. All the package dimensions were maintained the same as the reference package to allow direct replacement. As a result of the one-year-long development program, the required reliability and performance goals were met successfully. This paper mainly describes the WAVE package design for reliability and performance. Optimal lead design is the most important step for reliable package development. The WAVE geometry model (WAVEGM) was developed to analyze the lead type, lead orientation, bump height, and injection lift height. The 2-metal flex tape was chosen to replace the original 4-metal rigid substrate due to its thinner dielectric layer, lower dielectric constant and improved trace/space design capability. The electrical performance was verified by both simulation and actual measurements of a test device.

Reliability of high-end flip-chip package with large 45nm ultra low-k die

The ultra low-K (ULK) dielectric material employed in 45 nm process technology is more porous and brittle than low-K dielectric used in prior generations. This paper looks into the effects of packaging materials on the reliability of a 42.5 times 42.5 mm flip-chip package assembled by a 20 times 20 mm ULK daisy chain die with 180 mum bump pitch and organic build-up thin-core substrate. Underfill materials with low Tg and high modulus, high Tg and high modulus, and high Tg and low modulus have been evaluated. In addition the effects of die thickness were studied. Finite element modeling, room temperature coplanarity, component-level and board-level temperature cycling tests have been used to study the different underfill materials and die thicknesses. Results show that room temperature warpage, propensity for ULK delamination, and solder joint reliability were significantly affected by the underfill properties.