Once again, Gordon comes through with the scientific voice of reason.

Jim Smith
Managing Director
Cambridge Management Sciences, Inc.
4285 45th St. S.
St. Petersburg, FL 33711-4431
Tel: (727)866-6502 ext. 21
Fax: (727)867-7890
eMail: [log in to unmask]

"Davy, Gordon" wrote:
>
> A question has been raised about the appearance of solder alloys other than
> eutectic SnPb and whether non-shiny is acceptable. The terms "dull" and
> "grainy" were used. Allow me to quote from J-STD-001 (para. 9.2.4).
>
>         There are solder alloy compositions, component lead and terminal
> finishes, or printed board platings and special solder processes (e.g., slow
> cooling with large mass PWBs) that may produce dull, matte, gray, or grainy
> appearing solders that are normal for the material or process involved.
> These solder joints are acceptable.
>
> The surface of a solder connection has three visual attributes: luster,
> texture, and contour. The first two have to do with composition and cooling
> rate; the third with wetting. Except for those compositions that are at risk
> of lifting (as discussed recently in this forum), wetting is the primary
> reliability concern.
>
> Gordon Davy
> Northrop Grumman ESSS
> Baltimore, MD
> [log in to unmask]
> 410-993-7399
>
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