Agreed. The problem is, many vendors specify 6 months, regardless of how long it's useable.
I had this issue with R type paste. We'd buy in lots of 48 pounds of 1 lb tubs, and QA would have issues with the Certs as we would typically use that quantity in 8 to 10 months.
We will sequester out of date stuff from production, and use it for R and D.
Liquid fluxes which are based on alcohol are different. They are shipped in one gallon plastic containers, so we REALLY have to be aware of shelf life. The primary reason is the diffusion of the alcohol through the plastic containers. Unopened year old containers will start to suck in, deforming the container. We tried to reconstitute using the proper alcohol, never got it to work as well as new.. (btw, this is a problem with two part epoxy storage as well, you'll find that one or both container will start to collapse because some of the constituents are diffusing through the plastic container... Chemicals I cannot pronounce..
I see this problem with my plumbing work as well. End up throwing away flux, buying new every year or so. Even though the carrier is petrolatum jelly with tree sap as the active ingredient.
ps..Dirty jneutron??
Oh, one of your links said RMA had no halides...that is incorrect. There are many RMA fluxes out there with zinc chloride.
jn
Ah, I stand in awe. I only build components for the most advanced technologies in the world.
Someday, if I'm lucky, I'll reach the pinnacle of my profession....audio products. Then I too, can go into the production line with a boy scout knife, showing experienced solderers how to scrape wire leads..
jn
Using the materials as specified, i.e., comparing apples to apples, 60/40 will give a thicker coating because of a higher melt viscosity. Yes, changing other parameters will also change the thickness, but there is a significant difference at a fixed temperature between the two alloys.
The pinnacle of your profession isn't audio products- the bulk of that sector is engineered solutions, and their sales and popularity reflect this. To win awards from fashion magazines, you need to concentrate on the storyline and only work on products with minuscule sales. It helps to keep your head buried in 1968 and continue flogging minor variations of the same topology. Keep the true believers believing, that's the goal.
To quote Multicore solders app. instruction"Practical experience has shown that there can be advantages in having a plastic range.For joining on electronic equipment 60/40 alloy is often preferred to 63/37 for it obviates fractures which may occur owing to slight vibration whilst the solder is solidifying"
But I do not follow it as I have been using Multicore Ersin Sn62 for years.
Best Sn 60 solder I have ever used is a polish Cynel brand with genuine pine wood flux. BTW, do anybody know composition of famous Wonder Solder?
My preferred cleaning method is by steel wool , with more uniform cleaning action compared to scraping round leads with sharp tool.
But I do not follow it as I have been using Multicore Ersin Sn62 for years.
Best Sn 60 solder I have ever used is a polish Cynel brand with genuine pine wood flux. BTW, do anybody know composition of famous Wonder Solder?
My preferred cleaning method is by steel wool , with more uniform cleaning action compared to scraping round leads with sharp tool.
I solved the soldering QA problem long ago. I ask all potential technicians "Which end of a soldering iron do you hold?" Those who consider it a stupid question or give a theoretical answer are never hired. Hand scars are a plus!
Now in doing maybe one or two low level microphone connectors in the field, 63-37 yields about 1 failure per 1,000 connector pairs at six joints per pair. 60-40 yields 7. To do field wiring a tech must have done 1000 connectors at a bench without any bad ones.
I do get quantity pricing on connectors!
Now in doing maybe one or two low level microphone connectors in the field, 63-37 yields about 1 failure per 1,000 connector pairs at six joints per pair. 60-40 yields 7. To do field wiring a tech must have done 1000 connectors at a bench without any bad ones.
I do get quantity pricing on connectors!
Actually, regarding assembly techniques including soldering, I had a technician working for me with a curious personality (not uncommon, this), who combined two of the worst breadboarding techniques: On ground-plane pad-per-hole protoboards, he made solder connections with no mechanical support except the solder. It looked rather artistic in its way, and I think he thought me rather churlish to suggest that a bit of lead twisting before the soldering was a good idea. But when it came to inserting the axial parts, usually 1/8W resistors, he made them snug to the component side of the board by violently yanking them down from the solder side, frequently fracturing the coating over the end caps and creating intermittent shorts!
When I got vocally upset with him one day, really quite mildly, it so bothered him that he confided in a coworker that he could never work with me again. Shortly thereafter, management had fired almost everyone in the lab, except him. He was essentially unsupervised, and a while later he quit, citing overwhelming stress. You can't make this stuff up.
When I got vocally upset with him one day, really quite mildly, it so bothered him that he confided in a coworker that he could never work with me again. Shortly thereafter, management had fired almost everyone in the lab, except him. He was essentially unsupervised, and a while later he quit, citing overwhelming stress. You can't make this stuff up.
Back in the day, I had a similar technique for interviewing engineers. I would be chatting with them, and had an ostentatiously unplugged soldering iron on my desk. While we chatted, I would casually pick up the iron and reach over to touch them on the arm with it. If they stared at me and didn't move, the interview was over. If they flinched reflexively, they had a good chance at the job.
Ed, that input was impressive! I learned about SN63 solder, after 4 years being professionally in the field of electronics engineering, from a predecessor company, who ultimately made the Wall of Sound for the Grateful Dead, named ALEMBIC Inc, in 1970.
They found it important because of the problems of wiring 'snakes' for the sound system that they developed. I think one of my personal advantages in life, is that I do not throw information away, but learn from it the most that I can.
They found it important because of the problems of wiring 'snakes' for the sound system that they developed. I think one of my personal advantages in life, is that I do not throw information away, but learn from it the most that I can.
Steel wool IS an excellent lead cleaner, BUT it leaves little bits of steel wool around that can cause shorts. Also, it is oily due to the fact that it would rust otherwise, I presume, and this becomes a different contaminant that has to be dealt with. We did use it perhaps 30 years ago to some degree, but gave it up, because of the electrical shorts that we got from these almost invisible steel wool 'particles'.
Oh dear! That might lose me the job. Having noticed that the iron was unplugged throughout the interview I would be rapidly estimating how hot it might still be (assuming it was unplugged just before I arrived - the worst case) and so whether it might still do damage.SY said:
Was this an interview for scientists or technicians?
Well, you replied to one sentence I wrote out of context, "How we respond to sound is all about beliefs," and sounds like you missed the message. Yes people can hear audible differences, our auditory system works really good. And some sounds we have a natural dislike for that we find offensive.
The fact is that a stereo system sounds different all the time. We set the volume control at different levels - changing distortion, weather changes, listening position and so on ...
Why is it you only hear "break-in" of a new component? When you change something in your system, you start re-evaluating the sound.
There is also a ton of changing sounds and noise in your ears and brain, but these sounds are filtered out and we don't hear them at all. It's called habituation of perception. When we hear a new sound (or think we do) it starts a period of evaluation to form beliefs about the sound. Sounds we hear all the time with no particular importance are filtered out. This all happens in neuronal networks in the auditory pathways of the brain.
"Then we compared two transformers introduced to me as "transformer A" & "transformer B" and I noticed a slight difference, but this couldn't be be based on any belief because I knew absolutely nothing about either of them."
If the transformers were exactly the same you might also here are slight difference.
Anyway, making broad generalizations about equipment based on a hearing evaluation has it's pitfalls. Just saying that audiophiles should give their auditory system some consideration.
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Pavel, you are a real man.
SY if you had left it plugged in the good technicians would still stand out and the bad ones would have increased their knowledge base.
Brad I assume he was the lowest paid employee. As you know all people filling job descriptions are interchangeable. All personnel has to do is verify resumes. In the Harman Parallel Universe (HPU) Crown saved a bunch of money by getting rid of the higher paid folks and replacing them with the more up to date new graduates. Sheesh you relly should read some MBA textbooks.
My favorite case study is about how the railroads failed to get into the airline business.
SY if you had left it plugged in the good technicians would still stand out and the bad ones would have increased their knowledge base.
Brad I assume he was the lowest paid employee. As you know all people filling job descriptions are interchangeable. All personnel has to do is verify resumes. In the Harman Parallel Universe (HPU) Crown saved a bunch of money by getting rid of the higher paid folks and replacing them with the more up to date new graduates. Sheesh you relly should read some MBA textbooks.
My favorite case study is about how the railroads failed to get into the airline business.
Data?
I found some...
Here's the cover, I don't know how to give proper attribution, wrong language..maybe someone can help.
Physical properties of lead free solders in liquid and solid state
von der Fakultät für Naturwissenschaften der Technischen Universität Chemnitz
genehmigte Dissertation zur Erlangung des akademischen Grades
doctor rerum naturalium
(Dr. rer. nat.)
vorgelegt von Frau Souad Mhiaoui, M. Sc.
geboren am 16.08.1978 in Oujda/Marokko
Gutachter:
Prof. Dr. Jean-George Gasser
Prof. Dr. Bernard Legendre
Prof. Dr. Jens-Boie Suck
Diff doesn't look like it would vary much. Wish they compared 60/40 and eutectic..
Pic from page 140
I love the fact that typical solder pots run at 250 C, data on 60/40 only goes down to 400 C..sigh
jn
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I thought it was the free roads that killed rail travel and a lot of the freight.
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