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Research Papers

The Effects of Silica Fillers on the Properties of Encapsulation Molding Compounds

[+] Author and Article Information
Yowching Liaw

Department of Engineering Science,
National Cheng Kung University,
Tainan 70101, Taiwan

Jung-Hua Chou

Department of Engineering Science,
National Cheng Kung University,
Tainan 70101, Taiwan
e-mail: jungchou@mail.ncku.edu.tw

1Corresponding author.

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received November 5, 2016; final manuscript received June 13, 2017; published online July 10, 2017. Assoc. Editor: S. Ravi Annapragada.

J. Electron. Packag 139(3), 031007 (Jul 10, 2017) (6 pages) Paper No: EP-16-1120; doi: 10.1115/1.4037145 History: Received November 05, 2016; Revised June 13, 2017

Encapsulation molding compounds (EMCs) are commonly used to protect integrated circuit (IC) chips. Their composition always contains fillers of a large amount (about 70%) and will affect the properties of the compounds. Thus, in order to clarify the filler effects, in this study, three types of silica fillers including crystal silica, edgeless silica, and fused silica were studied experimentally to explore their effects on the compounds. The results show that all of the flow spiral length, glass transition temperature (Tg), coefficient of thermal expansion (CTE), and water absorption rate of the encapsulation molding compounds decrease as the filler amount increases, irrespective of the filler type. In contrast, both thermal conductivity and flexural strength of the compounds increase as the filler amount increases, but also irrespective of the filler type. For the three fillers, the edgeless silica filler has the advantage of a large flow spiral length and can be molded better. It also has a larger thermal conductivity, larger flexural strength, and lower water absorption rate. Hence, for low stress industrial applications, the edgeless silica should be adopted as the filler of the encapsulation molding compounds.

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Figures

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Fig. 1

Irregular polygons with sharp edges (D50 = 40 μm)

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Fig. 2

Edgeless silica (D50 = 40 μm)

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Fig. 3

Specimen size and the determination of Tg and CTE

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Fig. 4

EMC flow spiral length versus filler contents

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Fig. 5

Trends of viscosity versus filler amount in terms of KE

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Fig. 6

Filler amount versus KE

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Fig. 7

Variations of Tg versus filler amount (data standard deviation between 1.0–4.3  °C)

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Fig. 8

The variation of CTE versus filler amount

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Fig. 9

Water absorption versus filler amount

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Fig. 10

The variation of thermal conductivity versus filler amount

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Fig. 11

The effect of shape factor on the thermal conductivity ratio, Kc/Km

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Fig. 12

The trend of flexural strength versus filler amount (data standard deviation around 0.020–0.035)

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