Effects of reliability testing methods on microstructure and strength at the Cu wire-Al pad interface

Su, Peng; Seki, Hidetoshi; Chen, Ping; Itoh, Shingo; Huang, Louie; Liao, Nicholas; Liu, Bill; Chen, Curtis; Tai, Winnie; Tseng, Andy

doi:10.1109/ectc.2013.6575569

Cited by 8 publications

(2 citation statements)

References 7 publications

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“…Uno T [21] reported CuAl IMC interfacial corrosion under HAST environmental test. Yamaji Y et al [22] and Su P et al [23] reported similar CuAl IMC interfacial corrosion post HAST and UHAST tests and effects of pH of molding compounds on HAST failure rates. Lu YH et al [24] observed the growth rates of IMCs in Pd-coated Cu wire bonds are very sensitive to temperature, but the sequence of IMC formation remains the same for temperature below 350°C.…”

Section: Introductionmentioning

confidence: 70%

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

Gan

Francis²,

Chan³

et al. 2014

Gold Bull

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This paper discusses the microstructure evolution of copper (Cu) and gold (Au) ball bonds after various extended reliability stresses such as biased highly accelerated temperature and humidity test (HAST), unbiased highly accelerated temperature and humidity test (UHAST), temperature cycling (TC), and high temperature storage life (HTSL) in BGA package. Objective of this study is to study the microstructure evolution and changes after long hours and long cycles of component reliability stressing and its predicted failure mechanisms and to determine the long-term reliability comparison with combination of bonding wires in HAST, UHAST, and TC. Secondary electron microscopy (SEM) and energy dispersive X-ray (EDX) have been carried out to understand the respective microstructure of failed samples in HAST, UHAST, TC, and HTSL long-term reliability failures. Respective failure mechanisms of copper and gold ball bonds carrion under HAST and UHAST, ball bond lifting in TC and HTSL have been analyzed and proposed. The evolution of surface morphology, including copper and gold ball bond micro cracking, gold ball bond Kirkendall microvoiding and intermetallic compound (IMC) formation, was studied in FBGA package with copper and gold ball bonds during various reliability stresses. Biased HAST, UHAST, TC, and HTSL mechanisms were proposed to explain the observed morphological changes and the resulting ball bond wear out modes after extended reliability stresses. Weibull reliability analyses have been established to compare the performance of copper and gold ball bonds under humid and dry environmental tests.

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Section: Introductionmentioning

confidence: 70%

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

Gan

Francis²,

Chan³

et al. 2014

Gold Bull

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“…However, The diffusion of oxygen may accompany moisture absorption by molding compound. [14] After IMC corrosion, the void or crack forms at interface. Oxygen can diffuse through void or crack and react with Cu.…”

Section: Discussionmentioning

confidence: 99%

The corrosion performance of Cu alloy wire bond on Al pad in molding compounds of various chlorine contents under biased-HAST

Chiu

Chiang

Chen

et al. 2014

2014 IEEE 64th Electronic Components and Technology Conference (ECTC)

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The present article investigated the performance and interfacial behavior between Cu wire bond and Al pad under molding compounds of different chlorine contents. The epoxy molding compounds (EMCs) were categorized as ultra-high chlorine, high chlorine and low chlorine, respectively, with 24, 7.6, and 4.3 ppm chlorine contents. The ball bonds were stressed under 130 o C/85%RH with biased voltage of 10V. The interfacial evolution between Cu wire bond and Al pad was investigated in EMC of three chlorine contents after the biased-HAST test. The Cu bonding wires used in the plastic ball grid array (PBGA) package include bare Cu wire (4N Cu) and Pd coated Cu alloy wire (98Cu2Pd). The as bonded wire bond exhibits an average Cu-Al IMC thickness of ~0.12 µm in both types of Cu wire. Two Cu-Al IMC layers, Cu 9 Al 4 and CuAl 2 , analyzed by EDX were formed after 100h of biased-HAST test. The joint failed in 192h and 1296h, respectively, under ultra-high and high chlorine content EMC. The joint lasts longer than 2000h with low chlorine content EMC. The corrosion of IMC formed between Cu wire and Al pad, occurs in the ultra-high and high chlorine molding compound. The results of EDX analysis indicate that the chlorine ion diffuses from molding compound to IMC through the crack formed between IMC and Al pad. Al 2 O 3 was formed within the IMC layer. It is believed the existence of Al 2 O 3 accelerates the penetration of the chlorine ion and thus the corrosion.

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Effect of surface potential distribution on corrosion behavior of Cu/Al interface in Cu wire bonding applications

Mokhtari

Nishikawa

2020

Microelectronics Reliability

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Effects of reliability testing methods on microstructure and strength at the Cu wire-Al pad interface

Cited by 8 publications

References 7 publications

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

Evolution and investigation of copper and gold ball bonds in extended reliability stressing

The corrosion performance of Cu alloy wire bond on Al pad in molding compounds of various chlorine contents under biased-HAST

Effect of surface potential distribution on corrosion behavior of Cu/Al interface in Cu wire bonding applications

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