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Research Papers

[+] Author and Article Information
S. Abdullah

Advanced Semiconductor Packaging (ASPAC) Research Group, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor 43600, Malaysiashahrum@eng.ukm.my

M. F. Abdullah, A. K. Ariffin, A. Jalar

Advanced Semiconductor Packaging (ASPAC) Research Group, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor 43600, Malaysia

J. Electron. Packag 131(3), 031002 (Jun 16, 2009) (7 pages) doi:10.1115/1.3144155 History: Received September 19, 2008; Revised February 04, 2009; Published June 16, 2009

## Abstract

This study analyzed the reliability of two condition types of copper leadframe, namely, good and oxidized. Both types of leadframe were used in the fabricating process of a quad flat no-lead (QFN) package. Determining the adhesiveness of die strength and determining the strength of the leadframe are important in order for the package to obtain higher reliability. Commonly, an epoxy material is used in the die attachment process for die adherence onto the leadframe. A statistical analysis of the die shear test and the cyclic strain test of a QFN package was performed in this paper. From the application of the $t$-test method, the $p$-value shows a significant difference in die shear stress depending on leadframe condition. Based on a process capability ratio $(Cpk)$ above 1, the leadframe in good condition showed better processing capability than the oxidized leadframe. The Coffin–Manson approach was used in the cyclic loading of a QFN package to predict the package reliability in terms of cyclic strain. The leadframe in good condition showed a higher die strength value and lower microstrain compared with the oxidized leadframe. The oxidized leadframe provided a poor surface to attach adhesive and a higher microstrain on cyclic load, resulting in a negative effect on package reliability, such as a crack phenomenon at the epoxy interface between the die and the leadframe. This occurrence may ultimately cause delamination, which occurs between the die and the leadframe die pad.

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## Figures

Figure 8

Probability plot of shear strength on both leadframe types

Figure 9

Histogram and normal distribution of shear strength on both leadframes

Figure 10

Graph of strain versus time of a QFN package that used a good leadframe

Figure 11

Graph of strain versus time for a QFN package that used an oxidized leadframe

Figure 12

Power spectrum density of the QFN package using good leadframe

Figure 13

Power spectrum density of the QFN package using oxidized leadframe

Figure 14

C-SAM images obtained after 1000 cycles for (a) the good leadframe and (b) the oxidized leadframe

Figure 15

Cross section of the QFN package using the good leadframe

Figure 16

Cross section of the QFN package using the oxidized leadframe

Figure 1

Side view of the die shear test taken from the literature (11)

Figure 2

Top view of die shear alignment, as reported in Ref. 11

Figure 3

The XYZTEC CONDOR machine

Figure 4

Position of a QFN package on the INSTRON Micro

Figure 5

Schematic diagram of the position of the strain gauge on a QFN package when looking from the (a) the bottom view and (b) the side view

Figure 6

Top view image of good leadframe using an optical microscope; (a) before die shear and (b) after die shear

Figure 7

Top view image of oxidized leadframe using an optical microscope; (a) before die shear and (b) after die shear

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