Comprehensive Study on the Interactions of Multiple Die Shift Mechanisms During Wafer Level Molding of Multichip-Embedded Wafer Level Packages

Ling, Ho Siow; Bu, Lin; Choong, Chong Ser; Velez, Sorono Dexter; Chong, Chai Tai; Zhang, Xiaowu

doi:10.1109/tcpmt.2014.2316019

Cited by 21 publications

(4 citation statements)

References 8 publications

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“…The die shift is also dependent on wafer warpages and each process condition mainly including their temperatures [11]. Ling et al, have mentioned that 85% of die shift is resulted from thermal and mechanical (TM) effects such as Young's moduli and coefficient of thermal expansion (CTE) mismatches between the molds and carrier wafers, whereas the rest 15% is due to fluidic forces (FF) such as a shear force [12]. The TM-induced die shift can be lessened through increasing the die pitch/thickness [9] and decreasing the mold compound thickness [9].…”

Section: Introductionmentioning

confidence: 99%

Significant Die-Shift Reduction and μLED Integration Based on Die-First Fan-Out Wafer-Level Packaging for Flexible Hybrid Electronics

Fukushima

Susumago

Zhou

et al. 2020

IEEE Trans. Compon., Packag. Manufact. Technol.

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Typical die shift is beyond several tens micrometers or more, which is a serious problem on advanced fan-out wafer-level packaging (FOWLP), to give inevitable misalignment errors in the subsequent photolithography processes for fine-pitch redistributed wiring layer (RDL) formation. In particular, this problem is expected to grow all the more serious in chiplets and tiny dies less than 1 mm in a side. In this work, the use of an anchoring layer is proposed to fix these dies/chiplets on a double-side laminate thermo release tape and drastically reduce the die shift. In addition, an on-nail photoplethysmogram (PPG) sensor system as a flexible hybrid electronics (FHE) is integrated with μLED (270 μm by 270 μm) based on a die-first FOWLP methodology using a biocompatible polydimethylsiloxane (PDMS) mold resin for real-time monitoring pulse wave and percutaneous oxygen saturation (SpO2). The repeated bendability of fan-out Au wirings formed on the PDMS and the current-voltage (I-V) behavior of the μLED before and after die embedment in the PDMS is characterized.

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Section: Introductionmentioning

confidence: 99%

Significant Die-Shift Reduction and μLED Integration Based on Die-First Fan-Out Wafer-Level Packaging for Flexible Hybrid Electronics

Fukushima

Susumago

Zhou

et al. 2020

IEEE Trans. Compon., Packag. Manufact. Technol.

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show abstract

“…This slight shift in die location creates problems for subsequent wafer processing, such as the formation of redistribution lines. Previous studies indicated that both fluid loading and thermal mechanical mismatch during curing play key roles in this problem (1) .However, under different molding and curing conditions, as well as the used materials, the major controlling factor could be different case by case.…”

Section: Introductionmentioning

confidence: 99%

Thermo-mechanical and Mold Flow Analyses of Die Shift in Wafer Reconstitution Process for Advanced Packaging Technology

Yang

Liu

Chen

et al. 2017

The Proceedings of the 5th International Conference on Industrial Application Engineering 2017

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In advanced wafer level packaging, a process called wafer reconstitution was developed as a strategy for decoupling IC/MEMS fabrication and packaging. However, several concern such as die-shift and warpage are found during reconstitution and they induce problems for subsequent wafer process. In this paper, it is desired to examine the key factor of die-shift on wafer. The investigation procedures including fluidic and thermomechanical effects are introduced. Preliminarily, the die-shift problem is deduced as interaction of fluid load, thermal expansion, shrinkage of molding compound and viscoelastic effect. To gain a deeper insight, simplified fluid model and finite element analyses have been constructed to mimic the entire process. As current results shown, defects of molding is not the dominating factor in reconstitution process as those usually reported previously. Meanwhile, simulation of thermal model has a consistent tendency with actual situation and is close to the observed defects. In summary, the presented model in this work is able to provide the basis failure phenomena for the wafer reconstitution. However, the situations are actually sensitive to processing parameters and a more sophisticated finite element model to include those detail processing should be further developed for further optimizing the reconstitution process for a better yield models in the near future.

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“…Sharma et al [ 12 ] studied the effect of package specifications, operation temperature, and material on die shift and proposed a method to improve die shift by compensating for the measured die shift prior to the die-realignment stage. Ling and Bu et al [ 13 , 14 ] proposed a numerical analysis method that predicts a die shift by considering the molding-tape deformation behavior during the molding process, and performed theoretical research for predicting the die shift caused by mechanical effects during molding.…”

Section: Introductionmentioning

confidence: 99%

Compensation Method for Die Shift Caused by Flow Drag Force in Wafer-Level Molding Process

2016

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Wafer-level packaging (WLP) is a next-generation semiconductor packaging technology that is important for realizing high-performance and ultra-thin semiconductor devices. However, the molding process, which is a part of the WLP process, has various problems such as a high defect rate and low predictability. Among the various defect factors, the die shift primarily determines the quality of the final product; therefore, predicting the die shift is necessary to achieve high-yield production in WLP. In this study, the die shift caused by the flow drag force of the epoxy molding compound (EMC) is evaluated from the die shift of a debonded molding wafer. Experimental and analytical methods were employed to evaluate the die shift occurring during each stage of the molding process and that resulting from the geometrical changes after the debonding process. The die shift caused by the EMC flow drag force is evaluated from the data on die movements due to thermal contraction/expansion and warpage. The relationship between the die shift and variation in the die gap is determined through regression analysis in order to predict the die shift due to the flow drag force. The results can be used for die realignment by predicting and compensating for the die shift.

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Comprehensive Study on the Interactions of Multiple Die Shift Mechanisms During Wafer Level Molding of Multichip-Embedded Wafer Level Packages

Cited by 21 publications

References 8 publications

Significant Die-Shift Reduction and μLED Integration Based on Die-First Fan-Out Wafer-Level Packaging for Flexible Hybrid Electronics

Significant Die-Shift Reduction and μLED Integration Based on Die-First Fan-Out Wafer-Level Packaging for Flexible Hybrid Electronics

Thermo-mechanical and Mold Flow Analyses of Die Shift in Wafer Reconstitution Process for Advanced Packaging Technology

Compensation Method for Die Shift Caused by Flow Drag Force in Wafer-Level Molding Process

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