Flip chip issues

Bauer, CE, Let s talk chip scale. Circuits Assembly, IPC Supplement (Apr. 1997). Ngulty TA, Ekere NN. Chip scale vs flip chip issues to consider. Circuits Assembly. Nov. 1999. 

Ngulty TA, Ekere NN. Chip scale vs flip chip issues to consider. Circuits Assembly. Nov. 1999. 

Ngulty, T. A., and Ekere, N. N., Chip Scale vs Flip Chip Issues to Consider, Circuits Assembly (flow. 1999)... 

In this section, we will outline important research to address the design, testing, and manufacturing issues for 2.5-D ICs illustrated in the Fig. 8.1. below. In Fig. 8.1, the two chips are face to face bonded to ensure short vertical inter-chip connections. A heat sink is attached on the bulk side of one chip, while flip-chip based area I/Os are deployed on the back of the other chip. High performance circuits should be... 

Ceramic materials provide excellent CTE match between the die and package, which then reduces the risk of first-level solder bump failure in flip-chip applications. Unfortunately, this superb CTE match between the ceramic and the silicon die creates a large CTE mismatch between the ceramic package and the PWB. This CTE mismatch creates severe stress on the second level interconnects (see Fig. 58.31). This CTE mismatch, combined with DNP issues... 

Other component reliability issues related to lead-free solders include flip chips and wafer level CSPs with lead-free solder bumps and balls, where the higher soldering temperature and higher stiffness of the lead-free solder can adversely effect the reliability of the low-k dielectric layer on the die. Low k dielectric is needed for high speed applications, but is typically more fragile and prone to cracking. 

Gu, Y., Nakamura, T. Interfacial delamination and fatigue life estimation of 3D solder bumps in flip-chip packages. In Microelectronics Reliability, Vol. 44, Issue 3 (2004), pp. 471-483. 

Tran, S.K. Questad, D.L. Sammakia, B.G. Adhesion issues in flip chip on organic modules. IEEE Trans. Compon. Packag. Technol. (USA) December 1999, 22 (4), 519-524. 

An application utilizing gold-coated nickel particles has been reported to provide reliable connection to unbumped flip chips [30]. Another study showed that ACAs containing larger particles could accommodate planarity issues due to surface roughness and nonflat or nonparallel pads, compared to ACAs containing smaller particles. It was very difficult to obtain 100 /o consistency in conduction with unbumped flip-chip dice using ACAs with small diameter balls [31]. 

VIII. FLIP CHIP-RELATED ISSUES A. Characteristics of Some Lead-Free Solder Bumps... 

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