Factors governing the loop profile in Au bonding wire

Ohno, Yasuhide; Ohzeki, Y.; Aso, Teruo; Kitamura, Osamu

doi:10.1109/ectc.1992.204313

Cited by 15 publications

(12 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…But in the region next to the ball neck, the hardness has been observed to decrease upto a distance of around 166µm showing hardness decreasing with decreasing grain size, which is anti-Hall-Petch behaviour. The explanation of this observation lies in the thermal history of the neck region [9].…”

Section: Resultsmentioning

confidence: 99%

Mechanical Characterization of the Heat Affected Zone of Gold Wirebonds Using Nanoindentation

Shah¹,

Zeng²,

Tay³

2004

Journal of Electronic Packaging

View full text Add to dashboard Cite

Abstract-With increasing miniaturization in microelectronics the wirebonds used in IC packages are witnessing a thrust towards fine pitch wirebonding.To have a precise control over loop height of the wirebond for fine pitch wirebonding, it is imperative to do mechanical characterization of the wirebond. The present work studies the mechanical properties of gold wire and wirebond using nanoindentation. The wirebond specimen surface was planarized using mechanical polishing.The loop height of the gold wirebond is directly proportional to the length of the heat affected zone (HAZ) above the ball of gold wirebond. Metallographic preparation of gold wirebond cross section reveals the presence of undesirable coarse grain structure in HAZ due to recrystallization and grain growth in the gold wire adjacent to the ball. The recrystallization temperature of our gold wire was found using D.S.C. to be 340.66 0 C. The doping elements present in the gold wire used, were identified using TOF-SIMS. Nanoindentation of the gold wire was done at different maximum loads to observe the hardness variation with load. The nanoindentation of gold wirebond has confirmed a v-shaped hardness profile in the HAZ. The hardness minima for the particular gold wire used with a ball size ratio of 2.4 was observed at distance of 160-170 µm from the neck of the ball. The elastic modulus was found to vary randomly and to be independent of the microstructure in the wirebond. A yield stress profile based on empirical hardness-yield strength correlation has been predicted for the gold wirebond.

show abstract

Section: Resultsmentioning

confidence: 99%

Mechanical Characterization of the Heat Affected Zone of Gold Wirebonds Using Nanoindentation

Shah¹,

Zeng²,

Tay³

2004

Journal of Electronic Packaging

View full text Add to dashboard Cite

show abstract

“…Before measurement, the microscope was calibrated using standard calibration glass specimen. The procedure was similar to the one established by Shu [2,3] as shown in Fig. 1, with (X,Y,Z) = (0,O.O) was set at the centre of the ball at hondpad level.…”

Section: Free Air Ball Preparationmentioning

confidence: 99%

Looping behaviour of gold ballbonding wire

Saraswati

Theint

Stephan

et al.

Proceedings of 6th Electronics Packaging Technology Conference (EPTC 2004) (IEEE Cat. No.04EX971)

View full text Add to dashboard Cite

Gold ballbonding is an enabling technology in electronics packaging that accounts for around 90% of the world demand for packaged IC's. Thinner IC packaging demands lower wire loops and the stacked dies used for example in mobile telecommunications applications require a range of loop heights from very high to very low. In addition, multi-tier wirebonding also demands ultra low loop profile for its application. The lowest achievable loop heights are physically constrained by the wire dimensions and the plastic deformation behaviour of the wire. Ultra low loops result in extensive plastic deformation in the heat affected zone (HAZ). This paper examines the correlation between the wire properties (break load, modulus, hardness, grain size. HAZ length) and looping 'performance. The springback height of the lifted ball due to tension in the wire from bonding, and how it affects the looping behaviour is also discussed.

show abstract

“…Ohno et al observed that a V-curve hardness distribution near neck portion. This minimum hardness position corresponded to the maximum curvature in the loop profile [7]. Hu et al found that the neckdown region is also the heat affected zone [8].…”

Section: Introductionmentioning

confidence: 98%