JN, as well as coil winding, apparently you are also expert in soldering. Personally, I am not a soldering expert, but I have Manko's book: 'Solders and soldering' that gives me the info that I need. Surprisingly, I can still buy SN62 so I do. I have never been unhappy with it. My employers, who have to put my designs into production, have their own 'experts' and I do not interfere with what they do.
Maybe you can help me with soldering copper wire to gold plated connectors. I read a Wiki doc listing specifics of many solders. Most are not recommended for gold. Even the old standby 63/37 was identified as not recommended for gold. I have some high quality gold plated RCAs and XLRs with heavy gold plated solder cups. What would be an appropriate, rosin core, solder wire for connecting stranded copper, small like 14 AWG, wire to the gold connectors?
Thanks
Thanks
I have multiple hats, it comes with the territory. When I started coil winding, we were the only one on the third rock doing so at the needed precision. When we had to build a really big machine, we again were the only ones on the third rock to do so; I was the one called on to develop all the soldering processes, based on my industry experience.
Right now I'm dealing with radiation modified forward voltage distribution on a 3 inch diameter diode. One edge was heavily dosed, so it's forward voltage is higher for given current density. So, the less damaged side went into thermal runaway, as roughly a quarter of the disc had to support 6300 amps. And, you guessed it.. I am the only person on this rock with a cryo bypass diode that failed as a result of radiation gradient damage.. sigh, one day I'd like to google a task I'm assigned and actually find stuff on it..
I also prefer eutectic lead/tin for personal use, and I required it for all instrumentation outside of cryostats, lead free only for cryo use. They tried to ban lead/tin here a while ago, I raised a whole lot of dust...I won..
It's good that you have employers with their own staff who are experienced. Having people who are good at soldering is worth it's weight in gold..
I note you posted right away. Congrats...
John
Last edited:
Having solders "not recommended for gold" really doesn't tell you the whole story.
Gold is great for keeping the underlying metals relatively clear of oxides. As a result, soldering to even old gold plated surfaces is not a difficult thing (unless it's a thin layer of gold). Any old solder will typically be ok for soldering to gold.
HOWEVER, the problem is not how well it melts or bonds to the gold, but rather, the fact that gold/tin intermetallic will form, and that is very brittle, especially over time.
If you have gold plated surfaces you want to solder to, you really need to swamp out the gold using the solder of your choice first. For example, a gold plated lead can be tinned, cleaned, and re-tinned using a pencil or a pot. The purpose is to dilute the gold sufficiently that it won't go brittle. If you're using lead/tin, you will know you are good when the solidified solder surface is very shiny (the advantage over tin/silver here).
I will dip a gold plated lead into flux, then the pot, repeat multiple times until the lead is good and shiny, meaning no gold left to speak of.
An RCA or xlr, you can pre-tin, then wick out, then re-tin once or twice, that will clean the gold. Normal soldering to the cup will then be good to go. Another way to do it is to loosely mount the rca into an inch wide strip of aluminum, fill the cup, then whack the aluminum against a piece of 2 by 4 sitting on your bench, spraying the molten solder onto the awaiting wet cloth. Repeat a second time, then demount and use it in your application. I've used kelly clamps as well, but they will mark the threads too much. And, be very careful of flying solder drops..they hurt. (so I'm told)..😱😱
Edit: by the way, the process of swamping out the gold is the exact same process we use for swamping out tin plated ROHS components. For the reliability we require, we have to eliminate the tin plating, especially on the edges of formed leads, to eliminate tin whiskers. (apparently, stress/strain issues can cause whiskers as well) We conformal coat as well, but early analysis' showed that whiskers could be found working through the coatings.
John
Last edited:
I would love to see the photos of these esoteric projects that you have worked on. It seems like they all have somehow destroyed themselves. Its in your court.
On another note, if i am to be fired, I would love to see/hear about the projects that this new employment offer has for me.
Dont worry about responding, I am supposed to be a throne in your side. Its the only way this project will work, for you to be a relaxed yet confusing king.
On another note, if i am to be fired, I would love to see/hear about the projects that this new employment offer has for me.
Dont worry about responding, I am supposed to be a throne in your side. Its the only way this project will work, for you to be a relaxed yet confusing king.
Last edited:
There's one failure mode that never crossed my mind. 😀
I'm curious about the nature of the radiation damage - is the actual crystal structure of the diode being damaged (more defects being created) by the radiation? Are we talking fairly heavy particles in the radiation beam here?
Or does something else happen, such as the dopant molecules actually migrating through the crystal in response to the radiation gradient, so that the actual physical distribution/doping profile of the PN junction is altered over time?
-Gnobuddy
There are many projects, most are well published. Only the antimatter confinement guys were initially secretive, but they too eventually published.
Now, 20 years later, one diode finally fails due to unintended consequences.. so I get called in. Thank goodness I actually had stuff committed to paper, as nobody here can read 5 1/4 floppies where the test data resides. So far, I haven't had to get the backup tapes from back then, not even sure they are readable magnetically, nevermind format...
If the coherency of your resume is consistent with your postings on this forum, your resume would not get past initial viewing at HR.
John
Please pardon the simplicity of my answer, I'm just a country doctor jim..
It is the result of lattice defects causing recombination of carriers. The forward voltage curve is dependent on diffusion and recombination. I think SZE or Grove mentions it somewhere.
Back in the day, it was TRR that was all the rage (the dawn of SMPS). To make diodes turn off faster, diffusion would only get you so far without trashing forward voltage, breakdown, and leakage. So manu's would diffuse gold or platinum in to cause lattice defects for recombination, I believe some used other elements as well. (edit: shottky's work by sweeping the carriers out like a capacitor) Gold was a bit worse than platinum in that it caused more leakage, and very badly, it's leakage increased dramatically with temperature. This would cause thermal runaway of gold implanted devices during high speed operation as a result because of leakage dissipation, platinum held up better.
It was also possible to use ion implantation to speed the diodes up, but that pretty much cheating, as there would be partial healing over time. Mil spec frowned heavily on cheating on their devices.
All the things done to create lattice defects would raise the VF, increase reverse leakage, and speed up reverse recovery.
Course, back then, the largest devices I worked on were 40 amp shottky's, 356 mils square IIRC. To me at the time, a 3 inch PN disc was the middle step of the process, we would dice that up to make thousands of diodes.
I suspect the bulk of the damage we see is caused by neutron damage, with a large amount of x-ray as well. The source of the radiation was about an inch from the edge of a 3 inch disc. And since the damage to the lattice does NOT change the negative temperature coefficient of the pn junction, thermal runaway caused by hotspots still rears it's ugly head.
Trust me, you're not the only one who didn't think of the gradient damage. CERN alludes to gradient concerns in their 688 paper, but doesn't delve.
All the rad damage work done out there tends to deal only with uniformly spread damage.
John
Last edited:
I sit about 100 feet from a TARDIS.
Apparently, the head scientist on one of the beamlines is a fanboy, and spent too much time naming his endstation in a convoluted way just to use the acronym..
Sigh, some of these guys need to get out more often.
John
PROMETHEUS Energy Project, FP7 EU Project they really had to try hard for that one
I was involved in another prometheus https://en.wikipedia.org/wiki/Eureka_Prometheus_Project
Take lots of europeans, ply them with beer then offer prize for silly acronym contest?
I was involved in another prometheus https://en.wikipedia.org/wiki/Eureka_Prometheus_Project
Take lots of europeans, ply them with beer then offer prize for silly acronym contest?
Oh, and henry..I forgot to mention..
Never wipe molten solder off a surface that you are coating to remove gold and intend to solder to. If you do that, you remove the material that is easily wetted to, and the intermetallic remaining behind will oxidize instantly. That oxidized surface will then need a more active flux to break the oxide layer, and the flux in your flux core electronic solder may not be up to the task.. Plumbing flux will do it, but that stuff is nasty when it comes to electronics, as it will have zinc chloride as the activator. It will leave hydrogen chloride behind, not very nice.
John
Rellik, criticism can get pretty rough around here. I unfortunately am having trouble following some of your comments, myself, but I am not the problem. It is best, if you go after the 'critics' on this thread that you get your spelling and argument in order, or they will attack you on that severely, forgetting what you were originally trying to convey. Happens to me as well.
It's very easy to understand what he's trying to convey here John. Why you try to coddle someone with absolutely no technical knowledge is beyond me.
He has clearly stated that: (quotes are his words exactly)
""The lead free high silver content ones will eventually desentigrate""
""Sorry, firstly CERN does not use solder joints, the reflections caused by the differences in materials would cause serious errors in the measurements.""
""Secondly, I would hardly believe that a project as well planned as cern would ever have large pieces flying around.""
""Thirdly, radio does not use solder.""
""Where would helium serve a purpose in radio gear or cern? ""
""Lastly, you can cool something in vacuum. Its not a vaporization, its a sublimation due to a strikingly different temperature difference. Then you also have to consider the fact that the metal didnt even have to go through a phase change. ""
""the electricity being pumped into the solder will readily create silver odixe. This will readily slough off compared to a leaded solder where the lead oxide will retain less brittleness and emit its oxygen thus preserving the silver.""
""I have personally seen even eutectic solder vaporize off during the soldering process...This can be mitigated by dripping candle wax on your solder joints after they are complete to keep it held within.""
So, John...which of those statements do you believe???
Oh, let's not forget His stated purpose:
" I am supposed to be a throne in your side""
Granted, there appears to be an EFL problem as well (english as a foreign language), I've passed over the Jar Jar Binks level of english. But really John?? You are supporting an explosion in a technical dictionary factory..??
Why don't you tell your soldering experts all this stuff, and tell them to start dripping candle wax onto your boards to keep the solder from vaporizing? I hear it's a serious problem.
John
Last edited:
John you are knee jerk defending anyone who offends certain people here again with no regard to what they say, you are smarter than that.
- Status
- Not open for further replies.