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2005-11-21 by JanRwl@AOL.COM
"Tinpest" is NOT a problem with "tin solders" with other metals ALLOYED in with the tin, even when only 1% or so! Only "pure tin" can get tinpest below freezing! [Non-text portions of this message have been removed]
2005-11-21 by Alan King
JanRwl@... wrote: >"Tinpest" is NOT a problem with "tin solders" with other metals ALLOYED in >with the tin, even when only 1% or so! Only "pure tin" can get tinpest below >freezing! > > > The article I hit last week on it mentioning the military's unpreparedness for no-lead future said that the only thing that reliably stops tincicles is at least somewhere from 1-3% lead. Within the industry article, so while I didn't go looking for contradiction for it, I'd expect they'd probably know something about it since everyone's looking for the lead free cure. So more specifically lead, which won't be around for some of the people shortly. Can't remember if it was 2006 or 2008 they said EU was to be lead free.. Sneak a fishing weight into your solder bath and out pace your competition. Also amazing how many of the dead satellites that they've worked out after the fact died from it. Direct TV 3 and like 5 or 6 of the other failures just in the last 5 years or so. Alan
2005-11-21 by Stefan Trethan
Well, lead fishing weights are/will be banned quickly too. (The fishing junk often gets lost/discarded and kills water birds and other animals, and it is not nice to die of lead poisoning.) So if you try to outpace the competition this way you need to use something else, and you also need to make sure nobody checks your products, which will probably happen. I'm aware you were merely joking. I personally don't think lead in electronics has to be a problem, but if you look how it is discarded, it is a problem now. I think it would have been more efficient to act there. That said, i don't think it will be a problem for the stuff i do anytime soon. Lead solder might even get cheaper for a few years as it is replaced industrially. It's not bad that the tin stuff has a higher melting point, this way i'm sure it does not melt when i try to fuse the legend onto it. ST
On Mon, 21 Nov 2005 09:41:04 +0100, Alan King <alan@...> wrote: > > > The article I hit last week on it mentioning the military's > > unpreparedness for no-lead future said that the only thing that reliably > > stops tincicles is at least somewhere from 1-3% lead. Within the > > industry article, so while I didn't go looking for contradiction for it, > > I'd expect they'd probably know something about it since everyone's > > looking for the lead free cure. So more specifically lead, which won't > > be around for some of the people shortly. Can't remember if it was 2006 > > or 2008 they said EU was to be lead free.. Sneak a fishing weight into > > your solder bath and out pace your competition. > > Also amazing how many of the dead satellites that they've worked out > > after the fact died from it. Direct TV 3 and like 5 or 6 of the other > > failures just in the last 5 years or so. > > > Alan
2005-11-21 by ron amundson
Alan King <alan@...> wrote: JanRwl@... wrote: >"Tinpest" is NOT a problem with "tin solders" with other metals ALLOYED in >with the tin, even when only 1% or so! Only "pure tin" can get tinpest below >freezing! > When SAC solder is already shown to have problems with tin pest, chances are SA has a probability of having problems, and SC would be worse. The 1%Pb as mentioned earlier will alleviate the problem, and its hoped that contaminants within SAC other than lead will do the same. (Notice the term hoped). The EU directive comes into effect in mid year 2006, and CA here in the US is probably going to adopt something similiar. There are other problems with SAC that are also starting to show. Strange unexplained fractures, that are not a function of low temperature has the medical community really concerned. The probability is low, really low, so it may not be a big deal for stuff we do, but for those in high volume, or mission critical apps, its going to be a major concern. I know I would not want to be in consumer electronics customer service for the next couple years.Its going to be a nightmare, but then again when politics rules over science and economics, that tends to happen. The only good part is that perhaps the solder metallurgists have this solved, and are just keeping quiet on it, until **it hits the fan for their competition. Ron Here are some references off google http://www.semiconfareast.com/pbfree.htm http://www.indium.com/drlasky/files/TinPestPaper0723Final.pdf --------------------------------- Yahoo! FareChase - Search multiple travel sites in one click. [Non-text portions of this message have been removed]
2005-11-21 by Stefan Trethan
Anyway, i bought the more expensive silver paste because it must surely be better ;-) BUT, it seems to reflow in the same strange manner as the leaded paste. When you heat it until it has a dry, grayish appearance, and then wipe it off, it will come off as sort of dried paste/powder, BUT the board will be tinned in a thin, shiny layer. When you heat it further, until it reflows, it will get a dull, rough appearance from where the particles melted. I don't understand the first thing. How can it tin the board without melting, at all? What happens? ST
2005-11-21 by Alan King
Stefan Trethan wrote: >Anyway, i bought the more expensive silver paste because it must surely be >better ;-) > >BUT, it seems to reflow in the same strange manner as the leaded paste. > >When you heat it until it has a dry, grayish appearance, and then wipe it >off, it will come off as sort of dried paste/powder, BUT the board will be >tinned in a thin, shiny layer. > >When you heat it further, until it reflows, it will get a dull, rough >appearance from where the particles melted. > > >I don't understand the first thing. How can it tin the board without >melting, at all? >What happens? > > > > Think of having your board right at the melt point, and taking a solid lead pencil and writing on the traces. Pencil stays solid, but where you're touching the traces is melting. Traces are above the melt temp, but you're only getting melt when you make it touch. For sure it is melting some, just not a lot. Remember it takes a lot more energy for the phase change, so right near the melt temp you'll melt the surface but not have near enough extra heat to melt the rest of the solder balls. Might also be doing something with the flux at a higher temp, as someone else noted recently it stays on much longer just at the melt temp.. Think of how you draw on your iron tip with solder, as the iron is just heating up, leaves a nice shiny path. And won't melt the rest of the solder very fast yet, because it doesn't have enough extra heat. Things well above the melt temp uaually oxidize much faster than things right at it, part of the reason a temp controlled soldering iron is a good thing too.. Alan
2005-11-21 by Mike Young
Yes, sufficiently high temperature and dwell time are necessary. Lacking a controlled process, the simplest thing to do is cook and then overcook a few junk boards on a skillet and see what happens. (I have a few I can spare if you have not enough of your own. :) ----- Original Message -----
From: "Alan King" <alan@...> To: <Homebrew_PCBs@yahoogroups.com> Sent: Monday, November 21, 2005 2:46 PM Subject: Re: [Homebrew_PCBs] Re: Tinning the board? - reflow > Stefan Trethan wrote: > >>Anyway, i bought the more expensive silver paste because it must surely be >>better ;-) >> >>BUT, it seems to reflow in the same strange manner as the leaded paste. >> >>When you heat it until it has a dry, grayish appearance, and then wipe it >>off, it will come off as sort of dried paste/powder, BUT the board will be >>tinned in a thin, shiny layer. >> >>When you heat it further, until it reflows, it will get a dull, rough >>appearance from where the particles melted. >> >> >>I don't understand the first thing. How can it tin the board without >>melting, at all? >>What happens? >> >> >> >> > Think of having your board right at the melt point, and taking a solid > lead pencil and writing on the traces. Pencil stays solid, but where > you're touching the traces is melting. Traces are above the melt temp, > but you're only getting melt when you make it touch. For sure it is > melting some, just not a lot. Remember it takes a lot more energy for > the phase change, so right near the melt temp you'll melt the surface > but not have near enough extra heat to melt the rest of the solder > balls. Might also be doing something with the flux at a higher temp, as > someone else noted recently it stays on much longer just at the melt > temp.. > > Think of how you draw on your iron tip with solder, as the iron is > just heating up, leaves a nice shiny path. And won't melt the rest of > the solder very fast yet, because it doesn't have enough extra heat. > > Things well above the melt temp uaually oxidize much faster than > things right at it, part of the reason a temp controlled soldering iron > is a good thing too.. > > Alan > > > > > Be sure to visit the group home and check for new Links, Files, and > Photos: > http://groups.yahoo.com/group/Homebrew_PCBs > > If Files or Photos are running short of space, post them here: > http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ > Yahoo! Groups Links > > > > > >
2005-11-21 by Stefan Trethan
Nah, doesn't fit. If i heat with hot air from above the powdery stuff must be hotter than the board. ST
On Mon, 21 Nov 2005 21:46:59 +0100, Alan King <alan@...> wrote: > > > Think of having your board right at the melt point, and taking a solid > > lead pencil and writing on the traces. Pencil stays solid, but where > > you're touching the traces is melting. Traces are above the melt temp, > > but you're only getting melt when you make it touch. For sure it is > > melting some, just not a lot. Remember it takes a lot more energy for > > the phase change, so right near the melt temp you'll melt the surface > > but not have near enough extra heat to melt the rest of the solder > > balls. Might also be doing something with the flux at a higher temp, as > > someone else noted recently it stays on much longer just at the melt > temp.. > > > Think of how you draw on your iron tip with solder, as the iron is > > just heating up, leaves a nice shiny path. And won't melt the rest of > > the solder very fast yet, because it doesn't have enough extra heat. > > > Things well above the melt temp uaually oxidize much faster than > > things right at it, part of the reason a temp controlled soldering iron > > is a good thing too.. > > > Alan >
2005-11-21 by Alan King
Stefan Trethan wrote: >Nah, doesn't fit. > >If i heat with hot air from above the powdery stuff must be hotter than >the board. > >ST > > > Maybe simpler than what I was thinking anyway. When wiping, you are taking off the flux and oxides, when it just starts to reflow you are leaving them on. Try some test cases and go hotter. Haven't used this paste, but I think just in general reflow goes like this, then at a higher temp it goes shiny on its own. Maybe you're still not hot enough for full reflow.. Could be something just a little different with the paste though, plumbers typically do things a bit differently than how a no touch reflow goes.. Unless you wipe them with a rag, pipe joints are often dull right after making them. Divide and conquer, can't take more than 100 tests to figure it out exactly! :) Alan
2005-11-21 by lists
In article <op.s0k25tjimg0lsf@tu-x2pj5qeyp2u4>, Stefan Trethan <stefan_trethan@...> wrote: > That said, i don't think it will be a problem for the stuff i do anytime > soon. Lead solder might even get cheaper for a few years as it is > replaced industrially. More expensive I expect because it won't be made in such large quantities and the extra precautions neccessary when handling lead during the manufacture will make it so. Although all newly manufactured items will be required to have no lead there is a lot of stuff around that has leaded solder and in order to repair it you have to have leaded solder at your repair bench so it will still be on sale for a few (maybe 5-10) years after.
2005-11-21 by Stefan Trethan
I'll do that, but i'm positive the following will be the result: There will be one temperature where the "shiny thin layer with grey loose powder on top" will set in, and another where the solder reflows like normal. It seems the first temperature is considerably less than the second one, which makes me doubt the partial reflow theory, but i'll try and find out the temperatures. Plumbers reflow it fully, for sure, until the paste melts shiny and then you add some solder from a wire. I never felt the need to use those expensive pastes for plumbing, a bit of normal plumbing flux and wire seems just as good to me. The first shiny layer at low temperature would appeal for several reasons, but then it is surely very thin and much paste is wasted. maybe it could be recovered by scraping off and mixing with water. By the way the paste i have seems mixed with a cleaner, as it foamed up when mixed with water and shaken. It hasn't collapsed yet, i emptied the bottle leaving only a small amount, added some water, and now the bottle is again as full as it was with foamed paste. I wonder if it might be used for SMD in it's undiluted state, it sure is cheap... will try tomorrow... By the way - has anyone ever tried using a metal "sponge" made of fine stranded wire in a soldering iron as "tinning brush"? I think i might try to paint over a fluxed board with it. ST
On Mon, 21 Nov 2005 22:42:47 +0100, Alan King <alan@...> wrote: > > > Maybe simpler than what I was thinking anyway. When wiping, you are > > taking off the flux and oxides, when it just starts to reflow you are > > leaving them on. > > > Try some test cases and go hotter. Haven't used this paste, but I > > think just in general reflow goes like this, then at a higher temp it > > goes shiny on its own. Maybe you're still not hot enough for full > > reflow.. Could be something just a little different with the paste > > though, plumbers typically do things a bit differently than how a no > > touch reflow goes.. Unless you wipe them with a rag, pipe joints are > > often dull right after making them. > > > Divide and conquer, can't take more than 100 tests to figure it out > > exactly! > > > Alan
2005-11-22 by Mike Young
http://www.stencilsunlimited.com/TDS%20SynTECH.pdf http://www.stencilsunlimited.com/TDS%20NWS-4200-LF.pdf The first is a datasheet for tin/lead paste; the second for tin/silver/cu. The reflow profile is on page two of each. Flux activation happens around 140^C. Reflow doesn't begin until much higher, at 219^C for Sn/Ag/Cu. The spec'ed peak profile temperature is higher still, *minimum* 235^C. Full reflow will not be complete until 60 seconds after reaching 219^C. I suspect the residue is spent flux (?) and the shiny material might be unalloyed Sn in the paste reflowing at a lower temp. Just guessing. My paste is in the mail; I have nothing to do the next few days but kibitz your thinking. ----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...> To: <Homebrew_PCBs@yahoogroups.com> Sent: Monday, November 21, 2005 2:59 PM Subject: Re: [Homebrew_PCBs] Re: Tinning the board? - reflow > Nah, doesn't fit. > > If i heat with hot air from above the powdery stuff must be hotter than > the board. > > ST > > > On Mon, 21 Nov 2005 21:46:59 +0100, Alan King <alan@...> wrote: > >> >> >> Think of having your board right at the melt point, and taking a solid >> >> lead pencil and writing on the traces. Pencil stays solid, but where >> >> you're touching the traces is melting. Traces are above the melt temp, >> >> but you're only getting melt when you make it touch. For sure it is >> >> melting some, just not a lot. Remember it takes a lot more energy for >> >> the phase change, so right near the melt temp you'll melt the surface >> >> but not have near enough extra heat to melt the rest of the solder >> >> balls. Might also be doing something with the flux at a higher temp, as >> >> someone else noted recently it stays on much longer just at the melt >> temp.. >> >> >> Think of how you draw on your iron tip with solder, as the iron is >> >> just heating up, leaves a nice shiny path. And won't melt the rest of >> >> the solder very fast yet, because it doesn't have enough extra heat. >> >> >> Things well above the melt temp uaually oxidize much faster than >> >> things right at it, part of the reason a temp controlled soldering iron >> >> is a good thing too.. >> >> >> Alan >> > > > > > > Be sure to visit the group home and check for new Links, Files, and > Photos: > http://groups.yahoo.com/group/Homebrew_PCBs > > If Files or Photos are running short of space, post them here: > http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ > Yahoo! Groups Links > > > > > > >