RohS lead free soldering

[auplater]

Why would the alloy accuracy affect the process? Tens of degrees Kelvin is above the lead point, so phase constituents are not the issue, eh?

Did you mean ""bond niobium at 183 C for use at tens of kelvin""?

Cheers, John

Yeah right... we all got dressed up in cryo suits, jumped in a GREAT BIG dewer, and fired up the pumps and bonding equip...

problem was EE's using non-eutectic alloys at normal temps, not understanding phase relationships when working under a scope, producing joints that performed poorly when chilled and thermally cycled on phosphor bronze whiskers, often soldered to gold metallized quartz substrates.

keep the faith
John L.

 

[jneutron]

Yeah right... we all got dressed up in cryo suits, jumped in a GREAT BIG dewer, and fired up the pumps and bonding equip...

problem was EE's using non-eutectic alloys at normal temps, not understanding phase relationships when working under a scope, producing joints that performed poorly when chilled and thermally cycled on phosphor bronze whiskers, often soldered to gold metallized quartz substrates.

keep the faith
John L.

You hit the nail...the problem was ""EE's"".

Don't you know that you never give an EE (or ME or physicist) an object with which they can hurt themselves??? Scissors, staplers, forks...strictly against common sense to do so. And yet, you allowed them to even come near soldering irons???

Dangerous.

Cheers, John

ps...hand soldering on a quartz surface with (I assume) sputtered gold..that's a major recipe for disaster, scavenging all the gold would be a big problem...Was there an underlayer of nickel or silver perhaps?

 

[auplater]

SiO2 substrates

tell me about it...

i wasn't the one in charge.... but yes, they were Cr/Au sputtered... we often switched to ultrasonic bonding after I pointed and gold coated the whisker tips... and mentioned the solubility of gold in solder...

whisker pointing.. ugh.. does that bring back painful memories... don't ask

BTW: try mechanical bonding to 5 micron sputterred niobium films on quartz w/o damaging the photo defined geometry or electrical properties at superconducting temps...


l8tr
John L.

 

[jneutron]

Re: SiO2 substrates

tell me about it...

i wasn't the one in charge.... but yes, they were Cr/Au sputtered... we often switched to ultrasonic bonding after I pointed and gold coated the whisker tips... and mentioned the solubility of gold in solder...

whisker pointing.. ugh.. does that bring back painful memories... don't ask

BTW: try mechanical bonding to 5 micron sputterred niobium films on quartz w/o damaging the photo defined geometry or electrical properties at superconducting temps...


l8tr
John L.

pffft...give me something that'll take more than ten seconds with my eyes closed..... Ain't science fun?

I like wirebonding for that size. .7 mil gold... either TC or TS, depending on what the substrate can take.

Those weird things are the fun stuff, eh? Keeps woik from gettin boring..

Cheers, John

ps..not that I actually used the wirebonders (remember, safety rules for engineers)...we had some girls on the machines that could probably bond to the top of a glass of water...

 

[auplater]

Re: Re: SiO2 substrates

pffft...give me something that'll take more than ten seconds with my eyes closed..... Ain't science fun?

I like wirebonding for that size. .7 mil gold... either TC or TS, depending on what the substrate can take.

Those weird things are the fun stuff, eh? Keeps woik from gettin boring..

Cheers, John

ps..not that I actually used the wirebonders (remember, safety rules for engineers)...we had some girls on the machines that could probably bond to the top of a glass of water...

well.. that was then... I've moved on from all that tough scientific type stuff to easier pursuits... re: getting medical insurance operations to pay for all the work my wife does on her patients...

It's too bad for them I used to do that tough scientific stuff....

I work a system... they don't seem to know how to use theirs...

John L.