Hi Carl,
You did not say what the paste is.
When you have a high-melt SnPb ball and 63Sn/37Pb paste you wind up with a good solder joint having a gradient in Sn/Pb concentrations.
When you have a SAC ball and 63Sn/37Pb paste, it depends how long you are above the Liquidus temperature of the SAC solder and whether you get good mixing—while it is not the ideal solution alloy, with good mixing the fatigue resistance is comparable to SAC & SnPb.
In you case—well, IT DEPENDS.
Werner

 


 

 

-----Original Message-----
From: Carl Ray <[log in to unmask]>
To: [log in to unmask]
Sent: Wed, Mar 10, 2010 4:09 pm
Subject: [TN] Low Temp Solder Paste


Hi Technetters!!! I have a question regarding low temp solder paste and standard 
63/37 eutectic BGAs. Has anyone had any experience with this type of process? 
What are the pros and cons? Obviously the BGA doesn't see the temperatures 
needed for the balls to collapse so what type of solder joint do you end up 
with?


Carl Ray
Manufacturing Engineering Manager
Teledyne Electronic Manufacturing Services
1425 Higgs Rd.
Lewisburg, TN 37091
Direct: 931-270-2724
Cell: 931-637-5958
Email: [log in to unmask]<mailto:[log in to unmask]>


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