Warpage of QFN Package in Post Mold Cure Process of integrated circuit packaging

Sriwithoon, Nattha; Ugsornrat, Kessararat; Srisuwitthanon, Warayoot; Thonglor, Panakamon

doi:10.1088/1742-6596/901/1/012089

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…Chiu et al analyzed the reduction of warpage by stress relaxation of the thermal residual stress generated during the curing process of EMC as the cure time in the cure cycle increases . Sriwithoon et al also analyzed the warpage according to the cure temperature . However, the increase in the processing time results in an increase in production costs.…”

Section: Introductionmentioning

confidence: 99%

“…18 Sriwithoon et al also analyzed the warpage according to the cure temperature. 19 However, the increase in the processing time results in an increase in production costs. In addition to increasing the cure cycle time, Kim et al developed a smart cure cycle comprising a cooling and reheating process to improve the mechanical strength and fatigue life by reducing the thermal residual stress in the cocured steel/carbon epoxy composite structures by lowering the bonding temperature.…”

Section: Introductionmentioning

confidence: 99%

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Electronic Packaging Enhancement Engineered by Reducing the Bonding Temperature via Modified Cure Cycles

Park

Kim

et al. 2023

ACS Appl. Mater. Interfaces

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Semiconductor packaging continues to reduce in thickness following the overall thinning of electronic devices such as smartphones and tablets. As the package becomes thinner, the warpage of the semiconductor package becomes more important due to the reduced bending stiffness and driven by thermal residual stresses and thermal expansion mismatch during the epoxy molding compound (EMC) curing to create the package. To address this packaging reliability issue, in this study, we developed a modified cure cycle that adds a rapid cooling step to the conventional cure cycle (CCC) to enhance the reliability of the EMC molded to a copper substrate (EMC/Cu bi-layer package) by lowering the bonding temperature of the EMC/Cu bi-layer package. Modeling of the package via Timoshenko theory including effective cure shrinkage allowed the rapid cooling step to be quantified and confirmed via experiments. The modified cure cycle resulted in a 26% reduction in residual strain, a 27% reduction in curvature, and a 40% increase in peel strength compared to the CCC, suggesting that this is an effective new method for managing warping effects in such packaged structures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electronic Packaging Enhancement Engineered by Reducing the Bonding Temperature via Modified Cure Cycles

Park

Kim

et al. 2023

ACS Appl. Mater. Interfaces

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“…There are many studies [1][2][3][4][5][6] on strip warpage dealing with warpage problem in a molded package. They include warpage analysis considering the impact of design parameters and processing conditions, mold filling and curing steps, optimum combination of material properties, and the cure shrinkage of the mold compound.…”

Section: Introductionmentioning

confidence: 99%

Modeling Study on the Impact of Mold Thickness on Strip Warpage of a Molded Leadframe Package

Talledo¹

2021

JERR

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Strip warpage is a common problem in molded leadframe packages. When warpage becomes excessive, the strip could not be processed as it would result in the strip being stuck or damaged during loading to the handling machine loader. This study focuses on the impact of mold cap thickness on strip warpage of a molded Quad Flat No Lead (QFN) package to provide guidance in reducing the strip warpage to an acceptable level. Different mold thickness values were considered in the modeling using finite element analysis (FEA). Results showed that there is an optimum mold thickness, which is around 1.0 mm for 0.20 mm leadframe thickness and 0.65 mm for 0.125 mm leadframe thickness, that gives the lowest warpage in the case considered. The optimum mold cap thickness is lower for thinner leadframe. At mold thickness lower than the optimum value, warpage is in “frowning” mode and increases as the package gets thinner and this agrees with actual observations. This study shows that mold cap thickness has significant impact on molded strip warpage and could be assessed using FEA. Therefore, controlling the mold cap thickness could now be considered an option to reduce strip warpage in molded semiconductor packages as supported by modeling.

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“…Usually, the epoxy material is used for its good fluidity (Linec & Mušič, 2019), curing property and the capability to design integrated 3D shapes. To improve mechanical properties (Wang et al, 2002;Sriwithoon et al, 2017), electrical properties (Bell et al, 2017;Chandra et al, 2019) and control thermal dissipation, the epoxy resin is filled by silicon dioxide beads, also called nanosilica particles (Preghenella et al, 2005;Liang & Pearson, 2009;Dittanet & Pearson, 2012). For microelectronic applications silica beads added in the EMC material represent an ingredient with a proportion more than 50 Vol %.…”

Section: Introductionmentioning

confidence: 99%

Quantitative mapping of high modulus materials at the nanoscale: comparative study between atomic force microscopy and nanoindentation

Germanicus

Mercier

Agrebi

et al. 2020

Journal of Microscopy

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Summary Local mechanical properties of submicron features are of particular interest due to their influence on macroscopic material performance and behaviour. This study is focused on local nanomechanical measurements, based on the latest Atomic Force Microscopy (AFM) mode, where the peak force set point is finely controlled at each pixel. After probe calibration, we evaluate the impact of spring constant of two AFM hand‐crafted natural full diamond tips with steel cantilevers, used for mapping. Based on the fast capture of the cantilever deflection at each pixel and real time force curve analysis in the elastic region, AFM local measured contact moduli mappings of the silica beads (>50 GPa) incorporated in an epoxy resin matrix, are compared with those determined using classical instrumented nanoindentation tests. Our analyses show that with the two AFM probes, without local residual deformation, the high moduli of the silica beads measured with this advanced AFM mode are within the standard deviation of the values determined by classical nanoindentation. Lay Description The knowledge of material properties at the nanometer scale is a key parameter for well understanding and determining the behavior of material at macroscopic scale. In this paper, we compare two methods (an advanced mode and a classical one) based on the analysis of probes in interaction with the surface of studied material. We focus on a latest developed mode for determining local mechanical properties with a very high spatial resolution. For the advanced mode, we also consider two different hand‐crafted probes. Our analyses show that with the high spatial resolution advanced mode, local mechanical properties are well determined. We also highlight the impact of the properties of the used probes for this advanced mode. In a final step, the power of the presented investigation lies in the fact that it does not modify the topography of the surface.

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Warpage of QFN Package in Post Mold Cure Process of integrated circuit packaging

Cited by 5 publications

References 4 publications

Electronic Packaging Enhancement Engineered by Reducing the Bonding Temperature via Modified Cure Cycles

Electronic Packaging Enhancement Engineered by Reducing the Bonding Temperature via Modified Cure Cycles

Modeling Study on the Impact of Mold Thickness on Strip Warpage of a Molded Leadframe Package

Quantitative mapping of high modulus materials at the nanoscale: comparative study between atomic force microscopy and nanoindentation

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