Working Temperature Characterizations for Die Attach Films in Stacked-die Process

Tsai, Tsung-Yueh; Chang, Hsiao-Chuan; Li, Wei-Chung; Teng, Chi-Ping; Lai, Yi‐Shao

doi:10.1109/iemt.2007.4417058

Cited by 4 publications

(3 citation statements)

References 5 publications

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“…(5)(6)(7)(8) DAF is a film attached using an epoxy adhesive to the backside of the wafer after the wafer grinding and stress relief manufacture steps, to the object of attachment on the lead frame, or to the substrate of the assembly die bond manufacturing step: DAF includes the following material.…”

Section: Introductionmentioning

confidence: 99%

Design of UV Laser Parameters on Grooving Depth for Die Attach Film

2018

Sensors and Materials

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A die attach film (DAF) is a material that is used to attach dies to a substrate or lead frame during the die attach manufacturing step in the semiconductor IC assembly process, and the DAF UV laser half cut is a manufacturing step in the semiconductor IC assembly process, and the cutting performance affects the die bond chip pickup yield. Therefore, the optimization of laser half cut parameters is very important. In this work, different laser parameters were studied to find the significant factor parameters followed by the fine tuning of the optimization condition. Experimental results showed that the laser power and cutting feed speed are the significant parameters for achieving laser cutting quality. According to the design of experiment (DOE) results, in the laser power range of 0.5-0.8 W, the cutting feed speed range is 45-65 mm/s and the grooving depth is 15-20 µm, which are the optimized conditions of a 20-µm-thick DAF.

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Section: Introductionmentioning

confidence: 99%

Design of UV Laser Parameters on Grooving Depth for Die Attach Film

2018

Sensors and Materials

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“…By comparison to epoxy, the DAF requires some bonding delay and temperature to allow the DAF to melt, solidifies and stick to the leadframe or die. Previous study has indicated that most of the die stress is developed during die attach and curing process [2,3,[5][6][7] . When the die stress in the assembly processes is compared, it is found that DAF showed 42% lower stress than epoxy [7] .…”

Section: Introductionmentioning

confidence: 99%

“…3D packaging offers attractive way to reduce transmission delays, since its configuration provides much shorter access to several surrounding chips [1] . However, as the number of die stacks increases, DAF on the top die would experience decrease heating temperatures during top die attach process, higher power dissipation and higher thermal resistance between bottom and top die which may lead to weak adhesion and delamination due to high stress concentration [2,3] . There are two common adhesive material used for die stacking in the microelectronic packaging i.e., epoxy paste and DAF.…”

Section: Introductionmentioning

confidence: 99%

Effect of Manufacturing Stresses to Die Attach Film Performance In Quad Flatpack No-Lead Stacked Die Packages

1,2McBagonluri.¹

2009

American J. of Engineering and Applied Sciences

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Problem statement: Repeated heat cure during assembly processes affected the Die Attach Film (DAF) material properties and the effectiveness touched area that leads to weak die bonding and delamination. Suitable die attached condition and DAF material selection had been evaluated to achieve required reliability performance in the manufacturing of the 3D Quad Flat No-Lead (QFN) stacked die package. Approach: During this study, special attention was given to the development of the residual stresses due to mismatch in the coefficients of thermal expansion of different DAF materials. Both experimental and finite element method were employed to gain a better understanding in a stress development induced between two different type of DAF, different die attach temperature and during the manufacturing process. Differential scanning calorimetry (DSC) was used to measure the changes of heat flow characteristics for both types of DAF. The die bond strength results measured using shear testing machine were compared with the finite element method prediction. Results: Although both DAF samples achieved good reliability performance and passed the Moisture Sensitivity Level 3 test (MSL3) at reflow 260°C without any sign of delamination, numerical simulation had demonstrated that the stress development were increased exponentially as the die attach temperature increased. It showed that different DAF gave different values of stresses but presented the same trend which the lowest die attached temperature (100°C in comparison with 125°C and 150°C) gave more stress to the die and possibility that the die will have weak adhesion to the substrate was high. Conclusions/Recommendations: Therefore for this case, stress can be relieved by having higher die attached temperature with an adequate bonding force and time, however die attached temperature for both DAF must be used above the glass transition temperature (128°C for DAF A and 165°C for DAF B) and being controlled not to exceed the crystallization temperature (203°C for DAF A and 204°C for DAF B) of both DAF.

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