No, the alphas from lead are a real problem. Ten years ago, there were folks going round to churches with lead roofs, offering them a new lead roof in exchange for their old--and now low-alpha--lead ones.
Same with steel from old battleships.
Cheers
Phil Hobbs
The difference existed at least 30 years ago, when I bought my first roll of eutectic.
But where is the lead /within/ ICs? (The wires are bonded, not soldered.) Alpha particles have poor penetrating power.
No, you're not misunderstanding, and what you say is logical. But... This disparity existed 30 years ago, when I first bought a roll of eutectic solder. At that time, eutectic was less-common and less asked-for. That /might/ explain the difference.
Solder prices for single pound lots are all over the map- they change with voltatile metal prices and some distributors may have old stock.
There's been roughly a 4:1 price range in lead and 2.5:1 in tin over the past three years. Currently tin costs about 10x as much as lead, so you'd expect about a 10-11% price difference due to cost of the metals. At current prices there's around $5.30 worth of metals in a pound of solder, of which only 30 cents or so is lead. There's also the plastic spool, the cardboard box and 10-15 grams of flux.
Best regards, Spehro Pefhany
And then there is the shipping.
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No wonder I haven't seen those $4.95/lb. bar solder sales lately. I used to wait for those and stock up a couple hundred pounds for the soldering machine.
The fog is lifting...
Only a problem with flip-chip (C4) bonding. At one point I worked in the packaging research group at IBM Yorktown lab (no, I'm not a packaging guy--it's a long story).
Cheers
Phil Hobbs
The C4 balls were lead-indium, IIRC.
Lead-tin eutectic in my era (1987-2008), followed by gold-tin currently, IIRC.
Cheers
Phil Hobbs
The last time I dealt with any of this was in the mid '70s. Before TCMs, even (LEMs). I'm pretty sure they were lead-indium, but there may have been tin in there too. There was also an issue of polonium contamination causing uncorrectable L1 errors, but that's a completely different issue.
So you don't really know the composition of the solder in the pot, or how much copper, gold, etc. contamination there is?
No need to, really. it was used to salvage parts and tin wire. Most of the boards were soldered with 80/20 so i had to add some scrap lead from time to time, to lower the melting point. The other metals didn't hurt anything.
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