Jim - do you know by any chance what solder GM uses on their Alumina boards? I tried working on one board with 60/40 lead tin solder with no luck. The solder on the board had to be removed to get to copper. I was guessing the initial solder was incompatible and/or worked at a higher temperature.
Hul
Jim Thomps> > >> >> > >>
[snip]
I have no idea what is used now. I last ran a hybrid (alumina/beryllia substrates) facility in 1970-73. Back then we were using a solder with gold in it to avoid leaching the gold traces. Alumina boards with copper traces came after I left that part of the semiconductor biz.
I would hazard a guess that the present solder has some silver in it. ...Jim Thompson
I can't read it - or at least I'm not prepared to pay to access the full text - but it does seem to be a recent (2010) snap-shot of what's going on.
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
I suppose pure lead is a possibility (higher temp performance? RoHS exempt?), or bismuth (rather brittle to use pure, though?).
Anything tin-based should be regular RoHS style alloys (aside from the aforementioned gold $$$), which should be fine if you turn up the iron a bit. The substrate is probably doing a good job of heatsinking too, so you probably want to preheat it.
Tim
Gold itself is a pretty good solder. I suppose if you heat it locally with infra-red laser, it could be welded to silicon.
Crap! Even 0.18um is no big deal. This snipped-for-privacy@gmail.com is nothing but a bloviator. What don't you declare your credentials Edward? Degree? Company? Position? Preferred broom style ?>:-} ...Jim Thompson
Not interested in fame war.
Your "contributions" to this thread have never exceeded Popular Science level and have confused those seeking accurate information on making their own chips.
You have been dismissed from class. ...Jim Thompson
blue laser may work better, gold's reflective in the IR.
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