Effect of Au on the reliability of fine pitch surface mount solder joints

Conference · Wed May 01 00:00:00 EDT 1991

OSTI ID:5208317

Glazer, J ^[1]; Kramer, P; Morris, Jr, J W ^[2]

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1. Hewlett-Packard Co., Palo Alto, CA (United States)
2. Lawrence Berkeley Lab., CA (United States)

The effect of Au on the reliability of 0.65 mm pitch surface mount solder joints between plastic quad flat packs and Cu-Ni-Au FR-4 printed circuit boards was investigated. Cu-Ni-Au is a desirable printed circuit board finish for multi-chip modules or printed circuit boards that would otherwise require a selective Au finish, for example for edge connectors or wire bondable parts. However, Au is known to embrittle solder when it is present in sufficiently high concentrations, creating a concern that solder joint fatigue life in service will also be adversely affected. This paper reports the results of mechanical shock, mechanical vibration and thermal cycling testing of fine pitch solder joints containing varying amounts of Au. Tests were performed on as-soldered joints and on joints that had been heat-treated to evolve the microstructure toward equilibrium. The tests were designed to accelerate in-service conditions in a typical industrial environment. Under these conditions, the Au concentrations tested did not promote solder joint failures. Microstructural characterization of the distribution and morphology of the Au-, Ni-, and Cu-Sn intermetallics in the joint before and after accelerated testing was also performed. On the basis of these observations it is recommended that the Au concentration in solder joints between plastic quad flat packs and Cu-Ni-Au FR-4 printed circuit boards not exceed 3.0 wt %. 13 refs., 6 figs.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5208317
• Report Number(s): LBL-30881; CONF-9108172-1; ON: DE92000962
• Resource Relation: Conference: Surface Mount International (SMI) conference, San Jose, CA (United States), 27-29 Aug 1991
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
GOLD
METALLURGICAL EFFECTS
SOLDERED JOINTS
RELIABILITY
COPPER ALLOYS
GOLD ALLOYS
MECHANICAL VIBRATIONS
MICROSTRUCTURE
NICKEL ALLOYS
PRINTED CIRCUITS
THERMAL CYCLING
ALLOYS
CRYSTAL STRUCTURE
ELECTRONIC CIRCUITS
ELEMENTS
JOINTS
METALS
TRANSITION ELEMENTS
360101* - Metals & Alloys- Preparation & Fabrication
426000 - Engineering- Components
Electron Devices & Circuits- (1990-)