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Reply To: | TechNet E-Mail Forum. |
Date: | Tue, 30 Mar 1999 08:22:05 -0800 |
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Hello all,
Just a quick note for reference. The MicroBGA® CSP was designed to obviate
concern over the solder joint as a compliant element. In the µBGA® CSP, the
compliant layer in the package absorbs most of the stain of CTE mismatch
between silicon and FR-4 substate. As a result, the solder ball metallurgy
is not a great concern beyond allowing a good joint to be easily and
reliably formed in the assembly process and have sufficent strength to hold
fast the component in use.
Kind regards,
J. Fjelstad
At 12:41 AM 3/30/99 -0800, you wrote:
> Hi, Guenter, Werner...
> An opinion within the group of "leading lights" of UK technology,
> claim that "the lead free legislation is good timing" as Sn/Pb alloys
> do not have the reliability of other alloys, particularly with regard
> to modern components such as CSPs and Micro BGA.
>
> I have always understood that Pb makes Sn/Pb alloys very plastic and
> thus extreemly reliable under the stresses of thermal cycling.
>
> If there are more reliable alloys, what might they be?
> Which alloys present us with a higher degree of plasticity?
>
> Regards
> Edward Brunker
> PSION Computers
>
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