Reliability of Underfill-Encapsulated Flip-Chips With Heat Spreaders

Doi, H.; Kawano, Kenya; Yasukawa, Akio; Satô, Toshihiko

doi:10.1115/1.2792641

Cited by 14 publications

(5 citation statements)

References 2 publications

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“…It is commonly accepted that the dominant failure mode of FCOB assemblies with underfill is delamination of the underfill and the subsequent fracture of solder joints, which has been predicted in some finite element simulations (Madenci et al, 1998) and observed by experimental investigations (Nysather et al, 1998). However, some studies reported that delamination was not observed before the solder joint failure (Doi et al, 1998) and that the failure mechanism changed with improved underfill materials (Gamota and Melton, 1997;Rosson et al, 1999). Finite element simulation also shows that rapid failure of the solder joints can be significantly reduced by using an underfill with a low CTE, high Young's modulus and high Tg, even when a complete delamination occurred (Rzepka et al, 1998).…”

Section: Introductionmentioning

confidence: 96%

On the degradation of the solder joints of underfilled flip chip packages: a case study

Qun¹,

Xie²,

Liu³

et al. 2000

Soldering &Amp; Surface Mount Technology

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The lifetime of flip chip solder joints can be greatly increased by applying underfill encapsulation. This paper presents a case study where the thermal cycle lifetime was increased by more than 20 times, that is from ∼100 cycles to more than 2,000 cycles for a chip size of 5.6mm × 6.3mm. By combining electrical, acoustic and metallographic investigation, the degradation of the solder joints was monitored, some important factors relevant to solder joint reliability were analysed and discussed. Delamination was found not to be the dominant failure mode.

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Section: Introductionmentioning

confidence: 96%

On the degradation of the solder joints of underfilled flip chip packages: a case study

Qun¹,

Xie²,

Liu³

et al. 2000

Soldering &Amp; Surface Mount Technology

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“…The chip stress not only depends on fc and Is but also depends on the shape of the under-fill at the edge of the chip [3]. We thus evaluated the dependence on the shape of the under-fill, i.e.. h and I in the FEA model in Fig.…”

Section: Reliability Issuementioning

confidence: 99%

“…under-fills are inserted between the WPPs and the substrate. The reliability of solder joints between the WPP and the substrate is thus very high [3]. To further reduce the cost of the MCM, a low-cost FR-4 base is used a substrate on which the WPPs are mounted.…”

Section: Introductionmentioning

confidence: 99%

Highly reliable and low-cost multi-chip module composed of wafer process packages

Naka

Tanaka

Naitô

53rd Electronic Components and Technology Conference, 2003. Proceedings.

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A high-performance. low-cost, and highly reliable multichip module (MCM) was developed. It is composed of a MPU and a synchronous DRAM [i.e., wafer process packages (WPPs)] on a substrate, To reduce the cost of the MCM, a low-cost FR-4 base is used a substrate on which the WPPs are mounted. Since the mismatch between the thermal expansion coefficients (TEC) of the MPU and DRAM chips and the substrate increases, thermal deformation due to the mismatch may cause cracking of the chip or decrease the life of the solder joints between the MCM and a FR-4 base motherboard.To minimize the stress caused by thermal deformation in the MCM and, thus, to improve its reliability, the structure of the MCM was therefore optimized by finite element analysis (FEA). The FEA results show that thermal stresses in both the chips and the solder bumps are a function of the ratio of chip thickness (tc) and substrate thickness (ts), i.e., tclts, and these stresses decrease when tclts is decreased. Furthermore, thermal-cycling test results show that MCM reliability is assured when tclts is 0.5 or less. A MCM with tclts of 0.4, including a margin of safety, was developed. It was found that the life of this MCM is over 1000 cycles (no chip cracking and no solder joint failure) under thermal-cycling between -55°C and 125°C.

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“…with the d e f~t i o n of Mises inelastic strain rate p (5) where n is the stress exponent, D the drag stress, &, the reference strain rate, k the Bolmann constant, Q the activation energy for inelastic deformation processes, T the absolute temperature, respectively. However, the Mses equivalent stress G e is defined in different ways, which could be involved in a back stress, depending on specific constitutive model.…”

Section: Nonlinear Materials Models Of Solder and Underfillmentioning

confidence: 99%

“…Currently, most of analyses still use thermal elastic properties of undmfill encapsulants to perform iinite element simulation of Flip-chip package [5] [6][11]. The reason could be the lack of experimental data of nonlinear properties of underfills.…”

Section: Introductionmentioning

confidence: 99%

Fatigue life prediction of flip-chips in terms of nonlinear behavior of solder and underfill

Qian

Liu³

1999 Proceedings. 49th Electronic Components and Technology Conference (Cat. No.99CH36299)

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The nonlinear properties of eutectic solder and underfill FP4526 have been reported and incorporated into ABAQUS material model library for the fatigue life prediction of advanced electronic packages. The methods of unified constitutive modeling, separated Constitutive modeling, and fatigue life prediction have been described and compared in details. The nonlinear constitutive modeliig of solder alloys and underfills plays an important role in the life prediction in terms of the correct calculation of inelastic strain range and inelastic strain energy density of hysteresis loop under various accelerated test conditions. Combining with unified constitutive modeling, strain-based approach of life prediction is recommended in this paper. The analyses performed in this report present valuable insights for the design of advanced flip-chip packages.

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Reliability of Underfill-Encapsulated Flip-Chips With Heat Spreaders

Cited by 14 publications

References 2 publications

On the degradation of the solder joints of underfilled flip chip packages: a case study

On the degradation of the solder joints of underfilled flip chip packages: a case study

Highly reliable and low-cost multi-chip module composed of wafer process packages

Fatigue life prediction of flip-chips in terms of nonlinear behavior of solder and underfill

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