This is all true you will see a line between the solder and the termination coating for any material that does not become liquid
during normal soldering. Consider the first time you soldered to a Texas Instruments component with a palladium termination it did
not look like the standards but it was reliable.

The same variations can be seen on solderability testing times as well when using a wetting balance.


Bob Willis
Tel: (44) 01245 351502
Fax: (44) 01245 496123
Email: [log in to unmask]
Web Page: www.bobwillis.co.uk
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Web Page: www.online4training.com
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-----Original Message-----
From: Larry Tawyea <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 14 July 1999 16:24
Subject: Re: [LF] Solderability


>Andy,
>
>Everyone has a theory but hear is mine.  Given that all things are equal in a
>soldering operation, except for the fact that you are compensating your
>processing temperatures for the difference in melting point temperatures,
>there is a difference between eutectic solder and high tin alloys that will
>effect the physical appearance.  High tin solders have a much higher surface
>tension, approx. 20 to 30%, than eutectic tin lead solders.  This will effect
>the wetting angle or the spread rate when viewed visually.  I'm not sure how
>you are defining solderability since I have not followed the entire thread,
>but if you are using a visual criterion, this could be the reason why you are
>seeing a difference.
>
>Larry
>
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