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Research Papers

Effects of Stacked Layers and Stacked Configurations on Wire Sweep and Wire Sag of Advanced Overhang/Pyramid Stacked Packages

[+] Author and Article Information
Huang-Kuang Kung

Professor
Institute of Mechatronic Engineering,
Cheng Shiu University,
Kaohsiung City 83347, Taiwan
e-mail: hkkung@gcloud.csu.edu.tw

Chi-Lung Hsieh

Institute of Mechatronic Engineering,
Cheng Shiu University,
Kaohsiung City 83347, Taiwan
e-mail: k2957@gcloud.csu.edu.tw

1Corresponding author.

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received April 13, 2017; final manuscript received July 8, 2017; published online July 27, 2017. Assoc. Editor: Yi-Shao Lai.

J. Electron. Packag 139(4), 041002 (Jul 27, 2017) (8 pages) Paper No: EP-17-1042; doi: 10.1115/1.4037276 History: Received April 13, 2017; Revised July 08, 2017

Overhang and/or pyramid stacked packages are the trend in the semiconductor industry. As the stacked layers increase drastically, the wire sweep and wire sag problems become more and more serious. Based on some types of frequently used stacked configurations, their corresponding wire sweep and wire sag stiffness and deflections are investigated for extra-high stacked layers. Two typical profiles of Q_loop and S_loop wire bonds are included in this study. However, wire sweep and wire sag have to be considered in two different design aspects. For wire sweep, we have the conclusion that the maximum wire sweep deflections always occur near the central segment of a wire bond. As for the wire sag, the maximum wire sag may take place in the center region of the straight portion of a wire bond. The result shows that the deflections of wire sag can be reduced significantly by simply shifting the position of the kink or bend created within a wire bond. Finally, we have concluded that a stacked configuration with smallest bond span may be the preferred selection for the concerns of wire sweep and wire sag issues.

Copyright © 2017 by ASME
Topics: Wire , Deflection
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References

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Figures

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Fig. 1

Side view and top view of overhand four-die cross stacked configuration (type A)

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Fig. 2

Side view and top view of four same-die stacked configuration (type B)

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Fig. 3

Side view and top view of pyramid stacked configuration with single row bond pad arrangement (type C1)

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Fig. 4

Side view and top view of pyramid stacked configuration with multirow bond pad arrangement (type C2)

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Fig. 5

Side view and top view of pyramid stacked configuration with multirow bond pad and isobond span arrangement (type C3)

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Fig. 6

A schematic 3D wire bonds to indicate layer pitch and layer height

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Fig. 7

(a) Looping parameters of Q_loop wire bond profile, (b) looping parameters of S_loop wire bond profile, and (c) typical profiles of S_loop and Q_loop wire bonds for L2 = 0.5L

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Fig. 8

The sweep stiffness of four-layers B-type stacked configuration with S_loop and Q_loop wire bonds

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Fig. 9

The sag stiffness of four-layers B-type stacked configuration with S_loop and Q_loop wire bonds

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Fig. 10

The sweep deflections of B-type stacked configuration for four stacked layers with S_loop and Q_loop wire bonds

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Fig. 11

The sag deflections of B-type stacked configuration for four stacked layers with S_loop and Q_loop wire bonds

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Fig. 12

The sweep deflections of fourth-layer stacked configurations with S_loop and Q_loop wire bonds

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Fig. 13

The sag deflections of fourth-layer stacked configurations with S_loop and Q_loop wire bonds

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Fig. 14

The maximum sweep deflections of 4/8/12/16th-layers B-type stacked configurations with S_loop and Q_loop wire bonds

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Fig. 15

The maximum sag deflections of 4/8/12/16th-layers B-type stacked configurations with S_loop and Q_loop wire bonds

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Fig. 16

The effect of wire diameter on sweep deflections of B-type stacked configuration for layer 16th with S_loop and Q_loop wire bonds

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Fig. 17

The effect of wire diameter on sag deflections of B-type stacked configuration for layer 16th with S_loop and Q_loop wire bonds

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Fig. 18

The characteristic regions of wire sweep and wire sag for S_loop and Q_loop wire bond profiles: (a) typical Q_loop wire bond profile, (b) typical S_loop wire bond profile, and (c) S_loop wire bond with a kink or bend in the middle of bond span

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Fig. 19

The over-sag induced wire bond touch during the transfer molding process [16]

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