I'd say that that would be the case for high Pb balls, not for high
Sn balls.

  

-- 
Best regards,

Vladimir                          mailto:[log in to unmask]

SENTEC
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca

I disagree - with this type of component, the intent is not to create a homogeneous mix - the intent is to solder to the ball, and some amount of diffusion will occur in the process. Retaining the Sn90Pb10 ball gives the joint added height, which increases the reliability of the package.

The determining factors are those for a typical solder joint - ensure that the joint meets the appropriate reflow profile for the solder paste being used.

Ben


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev
Sent: Friday, February 27, 2009 11:07 AM
To: [log in to unmask]
Subject: Re: [TN] Reflowing CBGA component (with high Sn balls) using Eutectic solder paste

Hi Joe,

You have to make sure there is enough time above the liquids
temperature, as you'd want to get a homogenous mix of Sn and Pb in
the final joints.

-- 

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