High Temperature Storage (HTS) Performance of Copper Ball Bonding Wires

Saraswati,; Theint, Ei Phyu Phyu; Stephan, D.; Goh, H.M.; Pasamanero, E.; Calpito, D.R.M.; Wulff, F.; Breach, C.D.

doi:10.1109/eptc.2005.1614473

Cited by 22 publications

(7 citation statements)

References 4 publications

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“…For example, micro-hardness of copper powder has been measured equal to 72 HV in the study of Eksi and Kulecki. 146 Micro-hardness of high-purity (99.99% Cu) copper wires has been measured equal to between 90 and 110 HV-see Figure 3 in the study of Saraswati et al 145 The latter is more related to the present case because it accounts for work hardening in the production of copper. It was thus decided to use a value of 90 HV for the hardness of the copper particles, although many tests were done with different (higher and lower) values to check the trend of the results.…”

Section: Copper Particles In Rolling Contactmentioning

confidence: 98%

“…However, annealing and work hardening can result in micro-hardness values for copper in excess of 160 HV (see Figure 2 in the study of Poole et al 144 ) and, generally, much higher than values perceived in assuming that copper is not worked. 145 Most importantly, there is a great difference between the macro-hardness of pure copper in bulk form and the micro-hardness of micrometre-size copper particles having undergone annealing and/or cold working. For example, micro-hardness of copper powder has been measured equal to 72 HV in the study of Eksi and Kulecki.…”

Section: Copper Particles In Rolling Contactmentioning

confidence: 99%

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An experimentally validated numerical model of indentation and abrasion by debris particles in machine-element contacts considering micro-hardness effects

Nikas

2012

Proceedings of the Institution of Mechanical Engineers, Part J:

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Indentation and abrasion of machine-element contacts by solid contamination particles is a major problem in many industries and manufacturing processes involving the automotive, aerospace, medical and electronics industries among others. Published theoretical studies on indentation and soft abrasion of surfaces by ductile debris particles other than those of the author are based on several major simplifications concerning material properties, hardness, plasticity modelling, interfacial friction, kinematic conditions, etc. None of the studies published in the literature to date (2011) have those simplifications concurrently relaxed.In view of the shortcomings of existing numerical models on debris particle indentation and abrasion, and given the importance of dent geometry and size on fatigue life of machine elements, a greatly improved numerical model has been developed based on the previous studies of the author. The new model deals with elastoplastic indentation and abrasion of rolling-sliding, dry and lubricated contacts by spherical particles of any hardness, from very soft (e.g. 40 HV) to very hard (e.g. over 1000 HV), including harder than the contact counterfaces. The model incorporates strain-hardening and strain-gradient or indentation-size micro-hardness effects with an expanding-cavity plasticity model, a localised treatment of friction, generalised boundary and kinematic conditions involving localised stick and slip of the particle, linear and nonlinear work-hardening models of the particle, a basic approach on pile-up/sink-in plasticity effects and several other improvements. The model has passed extensive validation tests and found to give realistic predictions that are quantitatively quite close to the experimental results published by independent researchers in the literature concerning dent dimensions and slope. Moreover, it has verified and explained theoretically for the first time the formation of dimples inside and outside dents experimentally observed in rolling and rolling-sliding contacts. This article presents the mathematics of the model, the validation procedure with several real cases from the experimental literature, and a parametric study to show the model's predictions on precise dent geometry in several realistic cases.

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Section: Copper Particles In Rolling Contactmentioning

confidence: 98%

Section: Copper Particles In Rolling Contactmentioning

confidence: 99%

An experimentally validated numerical model of indentation and abrasion by debris particles in machine-element contacts considering micro-hardness effects

Nikas

2012

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…As the ultrasonic power increases, the ball shear force increases till it reaches a peak of 185 gf, then it decreases quickly. Shear strength is an indicator of bond interface properties rather than the shear force [19]. It was obtained by dividing the shear force by the area defined by the diameter of the deformed ball.…”

Section: Thermosonic Ball Bonding 321 Ultrasonic Powermentioning

confidence: 99%

Effects of process parameters on bondability in thermosonic copper ball bonding

Liu

Silberschmidt

et al. 2008

2008 58th Electronic Components and Technology Conference

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Thermosonic copper ball bonding is an absorbing interconnection technology that serves as a viable and cost saving alternative to gold ball bonding. Its excellent mechanical and electrical characteristics make copper ball bonding attractive for high-speed, power devices and finepitch applications. However, copper is easily oxidized and harder than gold, which causes some critical process problems in connection with bondability. In this study, a 50 µm copper wire with purity of 99.99% was bonded on aluminum metallization with thickness 3 µm using an ASM angle 60 automatic thermosonic ball/wedge bonder. Experimental studies of copper free air balls (FABs) formation and bonding process were conducted to establish the bonding mechanism and to explain the effects of process parameters on bondability. A micro-slipping model was proposed to account for the effects of the ultrasonic power and bonding force on bondability. It was found that the bondability was determined by a slip area at the bonding interface. The occurrence of bonding only at the periphery of the contact area between FAB and aluminum metallization was attributed to partial slips at the bonding interface. Variation in the ultrasonic power and bonding force that lead to different stick-slip modes, can effect bondability in the ultrasonic bonding process. It is important to set a proper bonding time to achieve interatomic bonding without causing fatigue rupture of microjoints. It was also found that preheating of the chip to a certain temperature can improve bondability.

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“…The bond reliability for Cu wire bonding has been reported [3,[9][10][11][12]. These studies mostly focused on thermal reliability under a dry atmosphere in HTS testing.…”

Section: Introductionmentioning

confidence: 99%

“…Gold prices have risen significantly so that demand for lower material cost has increased. There is growing interest in Cu wire bonding for LSI interconnection due to cost savings and better electrical and mechanical properties [1][2][3]. There are difficulties when implementing Cu wires in advanced LSI packaging such as fine pitch bonding [1,2].…”

Section: Introductionmentioning

confidence: 99%

Improving humidity bond reliability of copper bonding wires

Uno

Yamada²

2010

2010 Proceedings 60th Electronic Components and Technology Conference (ECTC)

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There is growing interest in Cu wire bonding for LSI interconnection due to cost savings and better electrical and mechanical properties. Conventional bare Cu bonding wires, in general, are severely limited in their use compared to Au wires. A coated Cu bonding wire (EX1) has been developed for LSI application. EX1 is a Pd-coated Cu wire to enhance the bondability.Bond reliability at a Cu wire bond under a humid environment is a major concern in replacing Au wires. The bond reliability of EX1 and bare Cu was compared in the reliability testing of PCT and uHAST (unbiased HAST). The lifetimes for EX1 and the bare Cu in PCT testing were over 800 h and 250 h, respectively. Humidity reliability was significantly greater for EX1. Continuous cracking was formed at the bond interface for the bare Cu wire. Corrosioninduced deterioration would be the root cause of failure for bare Cu wires. The corrosion was a chemical reaction of CuAl IMC (Intermetallic Compound) and halogens (Cl, Br) from molding resins. EX1 improves the bond reliability by controlling diffusion and IMC formation at the bond interface. The excellent humidity reliability of the coated Cu wire, EX1 is suitable for LSI application.

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High Temperature Storage (HTS) Performance of Copper Ball Bonding Wires

Cited by 22 publications

References 4 publications

An experimentally validated numerical model of indentation and abrasion by debris particles in machine-element contacts considering micro-hardness effects

An experimentally validated numerical model of indentation and abrasion by debris particles in machine-element contacts considering micro-hardness effects

Effects of process parameters on bondability in thermosonic copper ball bonding

Improving humidity bond reliability of copper bonding wires

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