Pre-tinning and flux considerations on the reliability of solder surface

Conference · Mon Jul 01 04:00:00 EDT 1991

OSTI ID:5239376

Sunwoo, A J ^[1]; Morris, Jr, J W ^[2]; Lucey, G K ^[3]

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1. Lawrence Livermore National Lab., CA (United States)
2. Lawrence Berkeley Lab., CA (United States)
3. Harry Diamond Labs., Adelphi, MD (United States)

The kinetics of wetting were studied on several different prepared surfaces of copper (Cu) to simulate the microstructure observed in pre-tinned Cu-clad printed circuit boards. The results illustrate the effectiveness of pre-tinning in maintaining the solderability of Cu surfaces. Pre-tinning with Pb-rich solder (95Pb-5Sn) is particularly effective since solderability is preserved even after a relatively long aging treatment. On the other hand, pre-tinning with eutectic solder risks the loss of solderability during aging or baking due to surface exposure of an {var epsilon}-phase intermetallic with poor wetting properties. The results also confirm the presence of carbon in pre-tinned specimens due to the use of flux. The effect of carbon on solderability is not yet known. 13 refs., 8 figs., 1 tab.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: DOD; Department of Defense, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5239376
• Report Number(s): LBL-31074; CONF-9108172--2; ON: DE92000905; CNN: MIPR No.R91-056
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
CARBON
COPPER
CRYSTAL STRUCTURE
ELECTRONIC CIRCUITS
ELEMENTS
FABRICATION
JOINING
JOINTS
LEAD ALLOYS
METALS
MICROSTRUCTURE
NONMETALS
PRINTED CIRCUITS
SOLDERED JOINTS
SOLDERING
TIN ALLOYS
TRANSITION ELEMENTS
WELDING
WETTABILITY