Very interesting Metallurgical data,   How would you relate this to
whisker formation and rate of growth of Tin whiskers??

How to control???
John Lynch
ON Semiconductor

tetsuro Nishimura wrote:
> 
> Dear Sir,
> 
>  The shrinkage of the surface of  lead free solder is appeared by difference
> solidification time. Tin Silver and Tin Copper makes inter metallic
> compounds that are higher melting points than Tin Silver's and Tin Copper's
> eutectic melting point. So that, after pile up intermetalic compounds then
> liquid solder solidifies with decreasing volume between intermetalic
> compounds.
> Another things, I have studied if contained small amounts of Nickel in
> Copper contained solder, such as Sn-0.7Cu, the shrinkage is much smaller
> than before adoption Ni. I believe Tin Nickel inter metallic compounds makes
> Tin Copper intermetalic compounds very small particles. If you interested in
> this, I want to discuss farther with you.
> 
> ********************************************
>  西村哲郎　Tetsuro Nishimura (Executive Director)
>  ㈱日本スペリア社　Nihon Superior Co.,Ltd.
>  TEL +81(06)6380-1121
>  FAX+81(06)6380-1262
>  E-mail : [log in to unmask]
>  HP : http://www.nihonsuperior.co.jp
> ********************************************
> ----- Original Message -----
> From: Guenter Grossmann <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, December 06, 2000 5:12 PM
> Subject: [LF] Antw: [LF] Pb-free appearance
> 
> Kirk
> 
> Two possies I know of for dull Pb free solder:
> 
> - Intermetallics swimming on the surface of the liquid solder.
> 
> - Shrink cracks along primarily solidified phases. These cracks are not
> deep. They form because SnAg phases solidify like dendrites leaving a
> certain amount of liquid solder so that a gap forms when the solder joint
> cools down. Eric reported about this not eutectic solidification.
> 
> Have a great day
> 
> Guenter
> 
> Guenter Grossmann
> Swiss Federal Institute for Materials Testing and Research EMPA
> Centre for Reliability
> 8600 Duebendorf
> Switzerland
> 
> Phone: xx41 1 823 4279
> Fax :      xx41 1823 4054
> mail:     [log in to unmask]
> 
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information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
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