A new high strength gold bond wire

Humpston, G.; Jacobson, David M.

doi:10.1007/bf03214723

Cited by 20 publications

(11 citation statements)

References 8 publications

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“…Although the ultimate tensile strength of 550 MPa at T)=5.6 for the Au-lOAg DMMC is much higher than the strength of pure annealed gold, it is lower than the ultimate tensile strength of several precipitationhardened gold alloys (egAu-1 wt%Ti with (JUTS = 1000 MPa) (20). It remains for future studies to determine whether deformation beyond T)=5.6 would further strengthen an Au-lOAg DMMC and whether the 10% Ag volume is optimal.…”

Section: Potential For Further Developmentmentioning

confidence: 81%

A new method for strengthening gold

Russell

Chumbley

et al. 1998

Gold Bull

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Metal-metal composites were first produced in a copper matrix in the 1970's, and they have since been produced in several other binary metal systems. This strengthening technique reinforces a ductile metal matrix with a ductile metal second phase. In some binary systems, this technique confers extraordinarily high strength and hardness while still maintaining low electrical resistivity. This article reports on the first gold matrix metal-metal composite, which was produced by deformation processing a 90%Au-l0%Ag powder compact. The Au-Ag specimen studied had an ultimate tensile strength of 550 MPa and an electrical resistivity only 8% higher than that of pure Au at a deformation processing true strain of 5.6. The 590 nm average Ag filament thickness in this composite was relatively coarse compared to other deformation processed composites, which suggests that substantially higher strengths would be possible in a gold matrix metal-metal composite using deformation processing to higher true strains to reduce the filament thickness. DEFORMATION PROCESSED METAL-METAL COMPOSITESDuring the past two decades, a new class of copperrefractory metal composites has been developed with extraordinary mechanical and electrical properties (1-3). These composites, composed of face-centered cubic Cu with 10 to 30% by volume element X (where X is a body-centered cubic metal immiscible in Cu, such as Nb, V, Ta, Cr, or Fe), are severely deformed by extrusion/swaging/wire drawing or by rolling to produce the nanometer-scale microstructure of X filaments in a Cu matrix shown in Figure 1. The Cu20%Nb system is the most thoroughly studied of these composites. These materials are best known for their extraordinary tensile strengths, which can be as high as 2400 MPa after deformation to a true strain (T) ) of 12 (4). However, they possess other unusual properties as well, including: strength-to-electrical-resistivity ratios much higher than those of any copper alloy the smallest filamentary microstructures (phase size) of any material available in bulk quantities phase structures with very low dislocation densities, approaching whisker quality in many cases The Cu-X deformation-processed metal metal £omposites (DMMC's) are characterized byremarkable ductility, which allows cast-or powder-processed 88 starting billets to be deformed as much as T) = 13.4 (5). Such deformations represent more than an 800-fold reduction in diameter and are accompanied by a concomitant reduction in the thickness and spacing of the X phase. Thus, an as-cast billet of Cu-20Nb, displaying Nb dendrites with an average thickness of

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Section: Potential For Further Developmentmentioning

confidence: 81%

A new method for strengthening gold

Russell

Chumbley

et al. 1998

Gold Bull

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“…Work hardening is therefore increased by solid solution hardening and grain refining effects, leading to much higher strengthening levels and also to increased recrystallization temperatures (22). Precipitation hardening, which gives stronger effects than those of the doping elements discussed above, can be obtained, for example by titanium (23,24). However, this approach is not yet commonly used because it is generated mainly by alloying elements that increase the corrosion risk and often give ball hardnesses which are too high.…”

Section: Enhanced Doped Gold Bonding Wires With Higher Strength / Purmentioning

confidence: 99%

Doped and low-alloyed gold bonding wires

2000

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Fine gold wires with diameters down to 15p.m are used for bonding semiconductor devices. Increasing miniaturization of electronic circuits calls for smaller wire diameters. This requires the development of gold wires with increased mechanical strength and good bondability to replace thicker wire diameters without detriment to their functionality. The first gold bonding wires were pure gold, and then doped gold wires of high purity were developed because of their stabilized and improved mechanical characteristics. Nowadays and in the near future low alloyed gold wires are increasingly replacing doped gold wires. This paper gives an overview of the mechanical characteristicsof doped and low-alloyed gold bonding wires and their bondability.Bonding wires serve as electrically conducting connections in integrated and highly integrated circuits (ICs), in automobile, power, and hybrid components. Usual diameters range from 500rm down to l Sum. Highest demands are made on the reliability and quality of the wires and resulting wire connections. The most important prerequisites are the uniformity and homogeneity of the wire and its mechanical and electrical characteristics. Thus, bonding wire producers are required to achieve the corresponding properties whilst meeting the highest quality demands.For automobile, power, and hybrid components socalled thick wires are used from l Ouprn to 500rm diameter. This wire range is usually made of aluminium and aluminium alloys in order to keep metal costs as low as possible.

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“…An earlier study of the Au-lTi alloy in wire form (5,6) demonstrated that a precipitation strengthening phenomenon is also observed after the material is drawn to a fine wire. In both cases, samples of the material are initially solution treated in a vacuum at approximately 850°C, water quenched and then cold worked as appropriate, followed by a heat-treatment at a lower temperature to develop maximum strength.…”

Section: The Enhanced Strengthening Of Au-iti Achievable In Fine Wirementioning

confidence: 99%

“…This was consistent with a limited diffusion path length of oxygen into the alloy, even when this is heavily cold worked. An experiment was undertaken to test whether oxidation is involved in the strengthening of Au-I Ti fine wire (5). A length of Au-ITi wire that had been drawn down to 25Jlm was divided into two halves.…”

Section: Anomalous Strengthening Mechanismmentioning

confidence: 99%

“…A more attractive application is the use of Au-I Ti in fine bondwire for electronic interconnection, which originally prompted this study. The stable oxide strengthening ensures that the boosted mechanical properties of the wire are resilient to subsequent thermal processing involved in electronics manufacture, which make it ideal for interconnects produced by both thermosonic ball-wedge and thermocompression wedge bonding (5).…”

Section: Uses Of Strengthened Au-lti Foil and Fine Wirementioning

confidence: 99%

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Stable strengthening of 990-gold

1996

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The addition of 1wt% titanium to gold was found to substantially harden the precious metal and enhance its wear resistance, which makes it attractive for jewellery applications. The enhanced hardening is due to the formation of fine AU4Ti precipitates under the appropriate thermo-mechanical treatments. It has been shown that another hardening mechanism can be induced in wire having a diameter of less than lOO/lm, which is stable to heating in air up to 200°C. These observations are consistent with the formation of a network of titanium oxide inclusions up to lOO/lm below the free surface, which has been reported elsewhere. New results have indicated that thin foil of Au-lTi, which has been subjected to similar thermo-mechanical processing, exhibits similar properties to those of fine wire of this material. Potential uses for the fine wire and foil are described.Age-hardened gold containing 1% Ti (990-gold) represents one of the most significant new jewellery alloys developed in the last 25 years (1). The fact that gold with up to 1% base metal content qualifies as '24 carat gold jewellery' in much of the Far East has provided the opportunity to choose an addition which substantially enhances the mechanical resilience of gold. Following a systematic study of additives which could be used to precipitation-harden gold at the 1wt% level, titanium was identified as the optimum element for this purpose, on both alloy constitution criteria and experimental findings.The addition of titanium to gold satisfies two important criteria for achieving optimum precipitation hardening.

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A new high strength gold bond wire

Cited by 20 publications

References 8 publications

A new method for strengthening gold

A new method for strengthening gold

Doped and low-alloyed gold bonding wires

Stable strengthening of 990-gold

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