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Can ROHS BGA be used with SnPb solder?

Associate III

It's my understanding that it is a bad idea to mix lead-free and leaded solder, and that it can cause cracks.

I'm using a TFBGA100 package on an STM32H7 and have some long-term reliability requirements. In order to avoid tin-whiskers, I was considering using SnPb (leaded) solder.

But then I started wondering, if the TFBGA uses collapsing solder balls, and the device is lead-free, wouldn't this cause issues with the leaded solder? The balls would be lead-free and the solder on the board would be leaded?

Does anyone have experience with this?

Douglas MILLER
ST Employee

Hello Adam,

Please check the following link for information on mixing leaded and lead free solder - 

Thanks for that link, however, I've already done a bunch of searching and reading; I was hoping to find something more official. Does ST recommend against using leaded solder on their BGA components?