Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Laminate materials

genesmelik

#6314

Laminate materials | 22 August, 2000

Dr. Lee,

Given the higher reflow temperatures for Pb-Free assembly, will common FR4 laminate materials be adequate, or do you believe that higher glass content boards will be required for mainstream Pb-free assembly? As a corollary question - if manufacturers resist adopting higher Tg laminate materials and stick with FR4, should we begin to see an increase in PCA defects because of delamination and warpage?

Regards,

Gene Smelik Cookson Performance Solutions

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Dr. Ning-Cheng Lee

#6315

Re: Laminate materials | 22 August, 2000

FR-4 will be OK for small products such as cellular phones. Here the temperature gradient across the board may be 3-4C only, and the board temperature can be well controlled. At temperature above around 245C, the discoloration and delamination may become more significant and cause reliability concerns. Warpage can also cause problem for large flat components such as BGAs. For large PCBs, due to the large temperature gradient developed across the board, some part of the board will see unacceptably high temperatures for FR4. For those applications, laminates with a higher Tg as well as a higher thermal stability will be needed.

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