The purpose of the present study is to understand the interfacial deformation between pad and wire and the effect of the pad thickness, the pad hardness, and the tool shape on the interfacial deformation. The relationship between the bondability and the interfacial deformation (surface exposure to produce the clean surface) is summarized, because the bondability is largely affected by the interfacial deformation. A simple model of wire bonding is proposed for the numerical analysis. The model is based on the finite element method for rate sensitive materials and applicable to very large deformation processes. The numerical simulation made it possible to visualize the interfacial contacting process which occurs for several milli-seconds. It was suggested that the periphery bond is produced easily as the pad thickness decreases and the pad hardness increases. On the other hand, it was found that the thick pad and the groove tool can help the center bond formation. These results is explained by the distributions of the interfacial extension and the equivalent stress on the bonding interface. Also, the damage to the substrate (Si chip) is discussed, based on the numerical results.

Issue Section:
Technical Papers
Keywords:
plastic deformation, hardness, lead bonding, interface phenomena, packaging
Topics:
Bonding, Deformation, Wire, Wire bonding, Stress
1.
Anderson, O. L., 1957, “Adhesion of Solids: Principles and Applications,” Bell Laboratories Record, Nov., pp. 441–445.
2.
Christensen, H., 1958, “Electrical Contact with Thermo-compression Bonds,” Bell Laboratories Record, Apr., pp. 127–130.
3.
Tomioka, T., et al., 1997, “Flip Chip Bonding Technology Using Thermosonic Bonding,” 3rd Symposium of Microjoining and Assembly Technology (Mate ‘97), Feb. 6–7th, Yokohama, Japan, pp. 9–14.
4.
Jellison
,
J. L.
,
1975
, “
Effect of Surface Contamination on the Thermocompression Bondability of Gold
,”
IEEE Trans. PHP
,
PHP-11
, No.
3
, pp.
206
–
211
.
5.
Bay, N., 1981, “Cold Pressure Welding---A Theoretical Model for the Bond Strength,” Proc. of the Joining of Metal: Practice and Performance. Vol. 2, Coventry, UK, 10–12th, Apr., pp. 47–62.
6.
Zhang
,
W.
, and
Bay
,
N.
,
1997
, “
Cold Welding---Theoretical Modeling of the Weld Formation
,”
Weld. J. (Miami)
,
76
, pp.
417-s–420-s
417-s–420-s
.
7.
Harman
,
G. G.
, and
Albers
,
J.
,
1977
, “
The Ultrasonic Welding Mechanism as Applied to Alminum- and Gold-Wire Bonding in Microelectronics
,”
IEEE Trans. PHP
,
PHP-13
, No.
4
, pp.
406
–
412
.
8.
Krzanowski, J. E., 1989, “A Transmission Electron Microscopy Study of Ultrasonic Wire Bonding,” Proc. of 39th Electronic Components and Technology Conference, 22th–24th May, Houston, Texas, pp. 450–455.
9.
Schwizer, J., Mayer, M., Bolliger, D., Paul, O., and Baltes, H., 1999, “Thermosonic ball Bonding: Friction Model Based on Integrated Microsensor Measurements,” Proc. of Inter. Electron. Manufact. Technol. (IEMT) Symposium, Oct. 18–19, Austin, TX, pp. 108–114.
10.
Winchell
, II,
V. H.
, and
Berg
,
H. M.
,
1978
, “
Enhancing Ultrasonic Bond Development
,”
IEEE Trans. Compon. Hybrids, Manuf. Telchnol.
,
CHMT-1
, No.
3
, pp.
211
–
218
.
11.
Takahashi
,
Y.
,
Shibamoto
,
S.
, and
Inoue
,
K.
,
1996
, “
Numerical Analysis of the Interfacial Contact Process in Wire Thermocompression Bonding
,”
IEEE Trans. Compon., Package. Manuf. Telchnol., Part A
,
19
, No.
2
, pp.
213
–
223
.
12.
Ishizaka
,
A.
,
Iwata
,
S.
, and
Yamamoto
,
H.
,
1977
, “
Formation of Clean Al Surface by Interface Deformation in Au-Al Thermo-compression Bonding
,”
J. Jap. Met. Soc.
,
41
, No.
11
, pp.
1154
–
1160
.
13.
Ahmed, N., and Svitak J. J., 1975, “Characterization of Gold-Gold Thermocompression Bonding,” 25th Proc. of Electronic Components Conf. (ECC), 12th–14th, May, Washington DC, pp. 52–63.
14.
Oh
,
S.
,
Bryant
,
M. D.
, and
Yune
,
Y. G.
,
1988
, “
Steady-State Contact Pressure in Electrical Contacts
,”
IEEE Trans. Compon., Hybrids, Manuf. Technol.
,
11
, No.
1
, pp.
106
–
111
.
15.
Saeki, H., Nishitake, H., and Yotsumoto, T., 1991, “Evaluation of Bondability of Au/Al by Deformation Analysis of Au ball,” Preprint of Autumn Meeting of Plastisity and Material Processing Soc., Sept. 25th–27th Sapporo, Japan, pp. 687–690.
16.
Takahashi
,
Y.
,
Koguchi
,
T.
, and
Nishiguchi
,
K.
,
1993
, “
Modeling of Viscoplastic Adhering Process by a Finite Element Technique
,”
ASME J. Eng. Mater. Technol.
,
115
, pp.
150
–
155
.
17.
Tomita
,
Y.
, and
Sowerby
,
R.
,
1978
, “
An Approximate Analysis for Studying the Deformation Mechanics of Rate Sensitive Materials
,”
Int. J. Mech. Sci.
,
20
, pp.
361
–
371
.
18.
Kashiwabara
,
M.
, and
Hattori
,
S.
,
1970
, “
Deformation Characteristics and Bonding Process of Al Fine Wire in Ultrasonic Bonding
,”
J. of Precession and Machine (in Japanese)
,
36
, No.
6
, pp.
388
–
393
.
19.
Garofaro, F., 1965, Fundamental of Creep and Creep Rupture in Metals, 1st edition, Macmillan, London, pp. 152–168.
20.
Takahashi
,
Y.
,
Inoue
,
M.
, and
Inoue
,
K.
,
1999
, “
Numerical Analysis of Fine Lead Bonding—Effect of Pad Mechanical Properties on Interfacial Deformation—
,”
IEEE Trans. CPT
,
22
, No.
4
, pp.
558
–
566
.
21.
Davies
,
P. W.
,
Dennison
,
J. P.
, and
Evaans
,
R. W.
,
1964
, “
The High Temperature Creep and Fracture of Polycrystalline Gold
,”
J. Inst. Met.
,
92
, pp.
409
–
412
.
22.
Bailey
,
J. A.
, and
Singer
,
A. R. E.
,
1964
, “
Effect of Strain Rate and Temperature on the Resistance to Deformation of Aluminum, Two Aluminum Alloys, and Lead
,”
J. Inst. Met.
,
92
, pp.
404
–
409
.
23.
Weertman
,
J.
,
1956
, “
Creep of Polycrystalline Alminium as Determined from Strain Rate Tests
,”
J. Mech. Phys. Solids
,
4
, pp.
230
–
234
.
24.
Onuki
,
J.
, and
Koizumi
,
M.
,
1996
, “
Effect of Si Precipitation on Damage in Ultrasonic Bonding of Thick Al Wire
,”
Mater. Trans., JIM
,
37
, No.
9
, pp.
1319
–
1323
.
25.
Onuki
,
J.
,
Koizumi
,
M.
, and
Ishikawa
,
I.
,
1996
, “
Effect of Frequency and Surface Cleanliness of Al-Si Electrode on Ultrasonic Bonding Characteristics of Thick Al Wire Bonding
,”
Mater. Trans., JIM
,
37
, No.
9
, pp.
1492
–
1496
.
Copyright © 2002
 by ASME
You do not currently have access to this content.