Aaaargh, lead free solder. Don't get me started. Oh, wait, too late, you got me started.vasimv wrote: Biggest problem of chips with BGA is lead-free solders used because ecology requirements. It tends to lose contacts with these because their temperature and mechanical characteristics, too fragile. I hope they will make special chip series with old fashioned Pb-based soldering for the mission.
I'm still nursing a couple of 40-year-old spools of Ersin Multicore I bought back in the last millennium.
The difficulty is, now it is getting hard to find parts that are not RoHS, i.e. lead free. Frequently the leads are tinned for compatibility with lead free solders, and don't work reliably with lead-based. I've had a job recently where I had to re-tin all the leads by hand in order to solder reliably. There are issues with gold plating, as well. Light gold platings are OK, heavy ones are not.
Tin solders used to be common in the early days of vacuum tube electronics. That's when it was discovered that tin solders make whiskers. Lead-tin solved the whisker problem. But now with lead removed, we're back to whisker problems, and with high component density and miserly contact spacing on boards, whiskers are more of a problem than ever.
Thus, we have yet another incentive to manufacture electronics on Mars ... that no lawyers angle means we could go back to reliable parts and solders.