Gold coatings for fluxless soldering

Jacobson, David M.; Humpston, G.

doi:10.1007/bf03214704

Cited by 59 publications

(47 citation statements)

References 13 publications

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“…Similar analyses have been performed on several other solder compositions [78]. The authors of Reference [78] predicted Au-Sn intermetallic particle formation (as a precursor to embrittlement) in lOOSn and 96Sn-4Ag solders at approximately 10% loading with Au.…”

Section: Alternative Soldersmentioning

confidence: 54%

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An overview of surface finishes and their role in printed circuit board solderability and solder joint performance

Vianco

1999

Circuit World

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A overview has been presented on the topic of alternative surface finishes for package VOs and circuit board features. Aspects of processability and solder joint reliability were described for the following coatings: baseline hot-dipped, plated, and plated-and-fused lOOSn and Sn-Pb coatings; Ni/Au; Pd, Ni/Pd, and Ni/Pd/Au finishes; and the recently marketed immersion Ag coatings. The Ni/Au coatings appear to provide the all-around best option in terms of solderability protection and wire bondability. Nickel/Pd finishes offer a slightly reduced level of performance in these areas that is most likely due to variable Pd surface conditions. It is necessary to minimize dissolved Au or Pd contents in the solder material to prevent solder joint embrittlement. Ancillary aspects that included thickness measurement techniques; the importance of finish compatibility with conformal coatings and conductive adhesives; and the need for alternative finishes for the processing of non-Pb bearing solders were discussed. IntroductionSuccessful manufacturing operations that use solder joining processes require the bonding (or "faying") surfaces of the circuit board and package VO (lead, termination, or castellation) to have adequate solderability. It is important to understand the functional definition of solderability in order to appreciate the role of surface finishes. Solderability includes two underlying properties, wettabizity andJlowabiZity or spreadability. Wettability is described as the capacity of the molten solder to interact with the base material by means of interfacial tension effects or, interfacial tension effects in combination with interfacial reaction processes, so as to develop an adherence between the liquid and the base material surface. The adherence must continue after the molten solder has solidified. The terms flowability or spreadability pertain to the molten solder being able to spontaneously cover

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Section: Alternative Soldersmentioning

confidence: 54%

“…The authors of Reference [78] predicted Au-Sn intermetallic particle formation (as a precursor to embrittlement) in lOOSn and 96Sn-4Ag solders at approximately 10% loading with Au. The low-temperature 58Bi-42Sn solder was affected by only 0.8% Au contamination.…”

Section: Alternative Soldersmentioning

confidence: 99%

An overview of surface finishes and their role in printed circuit board solderability and solder joint performance

Vianco

1999

Circuit World

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“…These metals are therefore solderable even without fluxes being present and, on that account, are suitable candidates for the required solder test substrates. Gold was selected in preference to platinum precisely because it is widely used in flux-free soldering applications [4].…”

Section: Development Of An "Ideal" Substratementioning

confidence: 99%

“…However, gold is highly soluble in most common solders and the resulting alloying alters their metallurgical and physical characteristics [4,5,6,7] , An exception to this trend is provided by some of the indium-based solders. These alloys react with gold to form an interfacial layer of the AuIn2 intermetallic compound [4], Once established, this layer tends to inhibit further interaction between the gold layer and the molten solder, thereby preventing the dissolution of gold by the solder reaching a level where it significantly modifies the metallurgical characteristics of the latter.…”

Section: Development Of An "Ideal" Substratementioning

confidence: 99%

Solder spread: A criterion for evaluation of soldering

Humpston¹,

Jacobson²

1990

Gold Bull

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“…If the ratio of gold in the metallization to tin in the solder exceeds a certain ratio, the AuSn4 intermetallic compound will form as the primary phase. It is well-known that this situation causes catastrophic embrittlement in gold-plated joints made with tin-based solders (other than the Au20wt.%Sn composition) [11]. Table III shows the concentration of gold needed to form; AuSn4 as the primary phase in the joint with each of the lowmelting-point solders.…”

Section: Preparation Of Bonded Specimensmentioning

confidence: 99%

Gold in gallium arsenide die-attach technology

Humpston¹,

Jacobson²

1989

Gold Bull

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Gold plays an important role in leading-edge semiconductor technologies based on gallium arsenide. This metal is used extensively in contact metallizations and in solders for bonding gallium arsenide devices into packages. The quality of soldered joints made to this semiconductor depends critically on the choice of the metallization/solder combination and bonding temperature. A set of design guidelines for achieving sound joints has been derived from a metallurgical study, which encompassed a representative selection of metallizations and solders employed in industry.

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Gold coatings for fluxless soldering

Abstract: Gold coatings play an important role in flux-free joining in a vacuum -a method widely used in electronics fabrication. In this process, the gold coating provides a substitute for the flux, ensuring that the surfaces of the joint are oxide free and solderable.

Cited by 59 publications

References 13 publications

An overview of surface finishes and their role in printed circuit board solderability and solder joint performance

An overview of surface finishes and their role in printed circuit board solderability and solder joint performance

Solder spread: A criterion for evaluation of soldering

Gold in gallium arsenide die-attach technology

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