Hi Rex,
Please be careful about the following:

(1) equating relative performance in accelerated testing to relative reliability performance—this is a classic apples v. oranges comparison;

(2) making a 'uniform' alloy from mixed SAC/SnPb solder combinations requires at least SAC reflow temperatures and more time than soldering just SAC;

(3) drawing any conclusions from one set of test results is quite 'dangerous' for Pb-free solders.




Werner


-----Original Message-----
From: Rex Waygood <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, 21 Oct 2008 12:08 pm
Subject: Re: [TN] Lead Free BGA'S








There is an NPL report that shows that this could be more reliable in
thermal cycle than either all SAC or all SnPb with the balls having
reflowed to produce a 'uniform' alloy. Obviously making an assumption
that some other BGA, thermal cycle routine, pad size etc will be the
same has risks but it was a good report. From memory the NPL under BGA
temp was 217C.


Rex Waygood
Technical Manager
 
PartnerTech Poole Ltd 
Benson Road
Poole
Dorset BH17 0RY
United Kingdom
 
Tel: +44 (0)1202 674333
Fax: +44 (0)1202 678028
DDI: +44 (0)1202 338222
Mob: +44 (0)7887 997403
 
[log in to unmask]
www.PartnerTech.co.uk

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Foster
Sent: 21 October 2008 16:21
To: [log in to unmask]
Subject: [TN] Lead Free BGA'S

Our assembly house recently assembled some boards with Lead Free BGA's
for us and when I asked them if they=2
0used a lead free process they
responded with.

We use leaded solder (Sn63Pb37) with a hybrid oven profile to
accommodate the lead-free BGA. I hope this answers your question. Please
let me know if you have any more questions."
Is this a common process, is this a reliable process

Any input is appreciated

Thank You
John Foster


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