In Situ Studies of the Effect of Ultrasound During Deformation on Residual Hardness of a Metal

Abstract

A method is developed using an ultrasonic wire bonder to systematically study in situ the effect of superimposed ultrasound during deformation on the residual hardness of a metal wire. The method is applied during ultrasonic ball bonding of Au wire. It is found that 69 mW applied ultrasonic power during deformation of the Au balls leads to lower residual hardness than similarly deformed Au balls without applied ultrasound; this may be beneficial in reducing defects in applications sensitive to bonding stresses. It is confirmed that, although samples deformed with applied ultrasound experience larger strain rates than samples deformed without, strain rate hardening (if it does exist) does not change the finding that ultrasound applied during deformation of Au leads to lower residual hardness.

Effect of EFO parameters and superimposed ultrasound on work hardening behavior of palladium coated copper wire in thermosonic ball bonding

“…The previously reported on-line method is used to evaluate FAB deformability by measuring FAB height (H FAB ) as illustrated in Fig. 1a and b, and deformed FAB height (H DEF ) [11][12][13][14][15][16].…”

“…The influence of US on the FAB deformability is investigated in a similar way as described in [13,14]. The evaluation procedure described in the previous subsection is modified to include ultrasound during FAB deformation.…”

Role of process parameters on bondability and pad damage indicators in copper ball bonding

“…6. Pre-bleed USG helps in reducing the risk of pad damage by producing softer deformed Cu balls after impact due to the usual amount of strain hardening being reduced by the ultrasound during the impact deformation (''acoustic softening") [31][32][33].…”

Rationally Designing the Trace of Wire Bonder Head for Large-Span-Ratio Wire Bonding in 3D Stacked Packaging

“…Gold wire bonding is the most commonly used technology to interconnect chips with low cost in microelectronics packaging. Since its invention in the 1960s, wire bonding has evolved into a dominant form of first-level chip or circuit interconnect with a large number of fixed user groups and equipment reserves [6][7][8][9][10][11][12][13]. Threedimensional stacked packaging through large-span-ratio and high-density wire bonding can maximize chip integration, boost the device performance, reduce the device size, and shorten the development cycle, which will further ensure a smooth transition of interconnect technology in the Post Moore Era [14].…”