Warpage analysis of epoxy molded packages using viscoelastic based model

Srikanth, Narasimalu

doi:10.1007/s10853-006-2373-9

Cited by 31 publications

(10 citation statements)

References 4 publications

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“…Tsai [4] modeled the molding compound behavior as temperature dependent elastic during cooldown based on the storage modulus obtained by the dynamic mechanical tests. Similar approach was often found in other literatures [5][6][7]. However, the storage modulus is another type of the modulus in frequency domain, and it cannot replace the Young's modulus without proper conversion process.…”

Section: Introductionmentioning

confidence: 53%

Warpage mechanism analyses of strip panel type PBGA chip packaging

Kim

Park

Choi

2010

Microelectronics Reliability

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Section: Introductionmentioning

confidence: 53%

Warpage mechanism analyses of strip panel type PBGA chip packaging

Kim

Park

Choi

2010

Microelectronics Reliability

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“…To determine the cure-kinetic model constants for the nonisothermal condition, data from the 2 • C/min, 3 • C/min, and 5 • C/min DSC experiments [17] were fitted by (2), and the fitted model constants are given in Table I. The comparison between the nonisothermal DSC experimental results and the fitted cure-kinetic model is shown in Fig.…”

Section: Dsc and Curing Kineticsmentioning

confidence: 99%

“…It is well known that the warpage occurs as a result of incompatible stress-free deformations among dissimilar package constituents. Many linear elastic-or viscoelastic-based analyses [1], [2] have been performed to investigate the warpage evolution of electronic packages under thermal excursion and had good correlations to experimental results. As the technology drives for miniaturization and system-in-package integration, the requirements for the warpage during package fabrication and board mounting processes are becoming more stringent.…”

Section: Introductionmentioning

confidence: 99%

Effects of Curing and Chemical Aging on Warpage—Characterization and Simulation

Chiu

Gung

Huang

et al. 2011

IEEE Trans. Device Mater. Relib.

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In this paper, the effect of the curing process on the warpage of an encapsulated electronic package is considered by using a coupled chemical-thermomechanical modeling methodology. A cure-dependent constitutive model that consists of a cure-kinetic model, a curing-and chemical-aging-induced shrinkage model, and a degree of cure-dependent viscoelastic relaxation model was developed and implemented in a numerical finite-element model for warpage simulation. Effects of polymerization conversion and chemical aging on the warpage evolution of a bimaterial dummy package after molding and during the postmold curing (PMC) process were investigated by using the proposed modeling methodology. Shadow Moiré warpage analyses were also performed to validate the numerical results. It was found from the warpage analyses that the chemical aging, while contributing little to the overall cross linking during the PMC, has a significant effect on the package warpage. The coupled chemicalthermomechanical model can be applied for performing numerical optimization for the packaging process and the assembly reliability.

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“…The subject of package warpage and stress resulted from CTE mismatch has been considered extensively, and quantitative models for packages under either assembly reflow or temperature cycling conditions were developed by many researchers, e. g., [2,3]. On the other hand, the effect of polymer chemical shrinkage on package warpage and stress was less discussed.…”

Section: Introductionmentioning

confidence: 99%

Effect of chemical aging on warpage for encapsulated packages — Characterization and simulation

Chiu

Huang

Lai

2011

2011 IEEE 61st Electronic Components and Technology Conference (ECTC)

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The effect of curing process on the warpage of encapsulated electronic package is considered by using a coupled chemical-thermo-mechanical modeling methodology. A cure-dependent constitutive model that consists of a cure kinetics model, a curing and chemical aging induced shrinkage model and a degree of cure-dependent viscoelastic relaxation model was implemented in a numerical finite element model for warpage simulation. Effects of polymerization conversion and chemical aging on the warpage evolution of a bimaterial dummy package after molding and during the post-mold curing (PMC) process were investigated by using the proposed modeling methodology. Shadow Moiré warpage analyses were also performed to validate the numerical results. It was found from the warpage analyses that the chemical aging, while contributing little to the overall crosslinking during PMC, has a significant effect on package warpage. The coupled chemical-thermomechanical model can be applied for performing numerical optimization for packaging process and assembly reliability. IntroductionThe tendency of thermosetting polymers to expand or contract more significantly than other package constituents during processing is widely recognized as a critical issue for electronic packages: from the assembly yield perspective, the deviation of the package from a planar state, or warpage, as a result of the mismatch in volume changes would increase the difficulty in achieving good interconnection to circuit board for surface mount area array packages; from the reliability perspective, the associated residual stress would accelerate defect growth and product failure. Polymeric packaging materials, such as epoxy molding compound (EMC), underfill, and substrates undergo significant volume changes during assembly processes because of their high coefficients of thermal expansion (CTEs) and the chemical shrinkage occurring at high temperatures.With the higher reflow temperatures associated with Pbfree assembly processes, packages are more prone to the warpage and stress issues related to the mismatch in package material expansion or contraction. In addition to that, the technology trend of system integration at package level and finer package-to-circuit-board-interconnect pitch are placing more tightened specifications on both coplanarity and inplane alignment accuracy. For example, in state-of-the-art embedded wafer level packaging process, two of the key challenges are the silicon die location shift and warpage of the reconfigured wafer, both of which are related to the shrinkage of the molding compound used for encapsulating the reconfigured wafer [1]. In order to meet the more stringent

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Warpage analysis of epoxy molded packages using viscoelastic based model

Cited by 31 publications

References 4 publications

Warpage mechanism analyses of strip panel type PBGA chip packaging

Warpage mechanism analyses of strip panel type PBGA chip packaging

Effects of Curing and Chemical Aging on Warpage—Characterization and Simulation

Effect of chemical aging on warpage for encapsulated packages — Characterization and simulation

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Warpage analysis of epoxy molded packages using viscoelastic based model

Cited by 31 publications

References 4 publications

Warpage mechanism analyses of strip panel type PBGA chip packaging

Warpage mechanism analyses of strip panel type PBGA chip packaging

Effects of Curing and Chemical Aging on Warpage—Characterization and Simulation

Effect of chemical aging on warpage for encapsulated packages &#x2014; Characterization and simulation

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Effect of chemical aging on warpage for encapsulated packages — Characterization and simulation