Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1991-05-28
1993-11-16
Tung, T.
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
204400, 204412, 204434, 228101, 228103, 228104, G01N 2726
Patent
active
052620220
ABSTRACT:
A sequential electrochemical reduction method and apparatus for assessing solderability of electronic component leads and printed wiring boards. The method detects and quantifies the oxides present on copper, solder, and intermetallics that are detrimental to solderability. A solderable portion of the component to be tested is immersed in an electrolyte to form an electrode. An inert counter electrode and a reference electrode are also placed in the electrolyte. A current is passed from the inert counter electrode to the tested component, and the potential between the component and the reference electrode is recorded as a function of time. In a plot of the electrode potential versus the total charge passed, a series of inflection points identify and quantify particular metallic oxides present on the solder. The plot is compared with previous analyses of aged specimens having known oxide compositions that correlate with degradation of solderability. The method is useful for testing off-the-shelf components and for control of circuit board manufacturing and assembly processes.
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Kolthoff et al., Polarography, 2d. ed., vol. 1, (1952), p. 395
Anderson Dennis P.
Tench D. Morgan
McFarren John C.
Rockwell International Corporation
Tung T.
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