tinning PCB's - Page 1
Forum section: electronics / general

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 07:40:45 am
content: Well like many people probably do I got some of that tinning powder you mix with water and put your pcb into to tin it.However I was thinking there might be another method. what about putting solder paste on the track of the PCB and then using a hot air gun to heat it ? would it work ? what exactly is solder paste, I work for a radiator manufacturer and they guy has a solder paste (solder + flux) that they paint onto stuff to tin it and get it ready for soldering together, same stuff maybe ?

author: tyblu
author_rank: Frequent Contributor
timestamp: January 07, 2011, 09:53:26 am
content: I just spread solder on it with an iron. If there are too many fine tracks to do this quickly (long <20mil data buses), I just do the pads and forget the tracks. Flux right before soldering helps. I'm thinking, however, of getting into electrochemical tinning after chemical treatments in order to do my own vias. Appears to require some intense, multi-step chemical treatment to get it to stick to drill bit glass transitioned FR-4 (bit melts and smoothes holes), but it doesn't seem too bad. Anything to keep it in my garage

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 07, 2011, 10:16:37 am
content: I used to use tinning solution a long time ago but don't bother these days - the stuff is expensive and solution doesn't last long.I just leave a coat of flux on to prevent the copper oxidising.

author: RayJones
author_rank: Frequent Contributor
timestamp: January 07, 2011, 10:27:30 am
content: Quote from: Simon on January 07, 2011, 07:40:45 amYeouch, I'm thinking that stuff would corrosive as all hell - we call it Bakers Flux - but it's used by plumbers, not technicians.NO NO NO.

author: Psi
author_rank: Super Contributor
timestamp: January 07, 2011, 10:56:30 am
content: Maybe you could get one of thesehttp://www.dealextreme.com/details.dx/sku.48764Fill it with solder then just spoon it onto the pcb and let it run back off into the pot?I have no idea how well it would work though, i just noticed those solder pots on DX a few days ago.You'd want a ceramic spoon though i think, to stop the solder sticking to it or burning you by heating up the spoon.They happen to have the correct plug for AU/NZ which is nice. (well, nice if your in AU/NZ)

author: tyblu
author_rank: Frequent Contributor
timestamp: January 07, 2011, 11:39:18 am
content: Quote from: RayJones on January 07, 2011, 10:27:30 amThere's tinning mixtures available that are meant for this:http://www.mgchemicals.com/products/421.html.Quote from: Psi on January 07, 2011, 10:56:30 amI would think that this wouldn't work very well without a PCB preheater to get the tracks up to temperature...

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 01:27:24 pm
content: I had thought of the pot, maybe I could try it at work in our tinning pit

author: comox
author_rank: Regular Contributor
timestamp: January 07, 2011, 01:47:58 pm
content: Tinning powder isn't worth the HASL.Get it? HASL?Har har har!!!! Bwaahahahahahha!But seriously folks, if your not rich like Dave and go for gold plating, go for Hot Air Solder Leveling. If your making your own, well, your on your own.

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: January 07, 2011, 02:54:08 pm
content: Quote from: Simon on January 07, 2011, 07:40:45 amPlumbing (radiator) solder paste is ground up solder in a flux (often acid based flux).Electronic solder paste is VERY precisely manufactured solder spheres suspended in a much less aggressive flux (rosin or no-clean). The point of the spheres is that they pack well and predictably into the openings in a stencil. While plumbing solder is usually simple tin-lead, solder paste can have other compounds (nickle, silver, indium) to improve wetting and performance in electronic applications.

author: TheDirty
author_rank: Frequent Contributor
timestamp: January 07, 2011, 03:17:28 pm
content: I once used a piece of solder wick soaked in solder and dragged around the board to tin a board just because I wanted it to look nice. It worked well. Otherwise I have no use for tinning boards and haven't done it since. The boards I haven't conformal coated tarnish and darken.

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 03:58:00 pm
content: well essentially I just want to protect the copper from oxidising, so if I just flux it that will do ?

author: wd5gnr
author_rank: Regular Contributor
timestamp: January 07, 2011, 04:11:13 pm
content: Instead of solder wick get the braid off some coax and use it to make a "snuggie" around your iron tiip. This will soak up solder and then you can drag it over the traces. I usually just use a conformal coating spray though. Of course, the boards that already have mask layers shouldn't be a problem.

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: January 07, 2011, 04:13:28 pm
content: No, flux won't. But paint will.Krylon Clear Gloss Enamel has always been my favorite. (sometimes color pigments are conductive)Be sure to test your specific paint before coating your board.

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 04:18:48 pm
content: yea paint is starting to sound attractive, but then will tinning help me solder SMD parts ?

author: mitpatterson
author_rank: Regular Contributor
timestamp: January 07, 2011, 04:27:39 pm
content: I have never used any of the solutions, normally what i do i just use a small bottle(with a needle tip that I got from mouser for flux, its just MG Chemicals Rosin Flux) and use that to cover all the traces and then just put a blob of solder on my tip and drag it around until i'm happy, normally works quite well, and normally after etching, but before "tinning" i use some scotchbright again to clean up the board and clean with IPA then flux and tin, works great for me.In regards to the via's someone mentioned, yah, that the same as MG chemicals makes a "professionals prototyping kit" that lets your make your own PTH, but its like a 5 step chemical process(involving fermaldiahite, what they preseve anamils for science in) a lot of carsiniginas, and that's just for the Electorless parrt, then you have to electricaly plate them, its a lot of work, and 2 of the chemicals are only good for like 2 days after mixe, and then you ahve a lot of chemcilas to dispose of, but i miss PTH on home made boards, make 2 sided boards hard to do and solder though hole components, but i digress.

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 04:40:06 pm
content: has anyone ever tried dipping the board in a solder bath ?

author: TheDirty
author_rank: Frequent Contributor
timestamp: January 07, 2011, 06:25:42 pm
content: Yikes, like that solder dipping shown in one of the other threads?If I don't want it to tarnish, I just spray it with a bit of conformal coating. I have the cheaper acrylic stuff rather than the nicer silicon based coating. Otherwise I haven't found any issue with tarnished boards, I just let them tarnish as long as they have all the components on them already.

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 06:36:04 pm
content: you mean the copper won't eventually wear away when tarnished ?, I have a high current project that could do with no tin for heat dissipation

author: mitpatterson
author_rank: Regular Contributor
timestamp: January 07, 2011, 07:19:18 pm
content: Quote from: Simon on January 07, 2011, 06:36:04 pmNormally with most oxides they are actually, believe it or not, a protective barrier to prevent further oxidation, now i can't say it won't wear away after 100 years, but in the short term(5-10 years) i don't know why it would. because the layer on the outside actually acts to protect whats underneath from oxidizing.

author: Simon
author_rank: Unknown
timestamp: January 07, 2011, 07:28:58 pm
content: hm yes that's what I'd think, but 35um is not a lot. I suppose i worry because i took apart a prototype we were given at work and the thin traces were falling apart but then I don't know what he had been doing with it

author: Zero999
author_rank: Super Contributor
timestamp: January 07, 2011, 08:27:52 pm
content: Use a conformal coating to prevent tarnishing. The one I use can be easily soldered through so I coat before soldering if I know I'm not doing to solder it all in one go.

author: RayJones
author_rank: Frequent Contributor
timestamp: January 07, 2011, 09:16:23 pm
content: Quote from: tyblu on January 07, 2011, 11:39:18 amSorry, I quoted too much, I was referring to the radiator solder paste.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: January 07, 2011, 11:33:24 pm
content: I use MG Liquid Tin For Copper Circuits, with very good results for me.David.

author: TheDirty
author_rank: Frequent Contributor
timestamp: January 08, 2011, 06:24:21 pm
content: The oldest unprotected copper PCB I have is about 6 years old I think. It's darkened but it's not noticeably corroded. The darkest ones are ones that I handle regularly.

author: joelby
author_rank: Frequent Contributor
timestamp: January 09, 2011, 10:50:16 pm
content: I silver plate boards using Cool-Amp powder. You just tip some powder onto the board and using a damp paper towel or similar, rub until it's coated.A bit more information here:http://www.cool-amp.com/cool_amp.htmlAvailable in smaller, cheaper quantities fromUltrakeet.

author: DJPhil
author_rank: Frequent Contributor
timestamp: January 10, 2011, 12:19:11 pm
content: Quote from: joelby on January 09, 2011, 10:50:16 pmInteresting stuff!What's the solderability like? I imagine you'd have to use 2% silver solder for best results, though that's just a guess. I'd give it a whirl if I could solder to it with my favorite 63/37 health hazard solder.

author: joelby
author_rank: Frequent Contributor
timestamp: January 10, 2011, 12:28:31 pm
content: Quote from: DJPhil on January 10, 2011, 12:19:11 pmPretty good! Much better than tarnished copper. I use 60/40 solder I bought from Dick Smith in 1990 and have no complaints (other than abdominal pain, confusion, headache, anaemia, irritability, coma, and death).I asked Ahmad at Ultrakeet about this very issue, and he said that it makes no difference at all, but that the 60/40 solder seems to work better.

author: Simon
author_rank: Unknown
timestamp: January 10, 2011, 12:40:05 pm
content: would a micro inch be 0.000001 of an inch ? never heard that one before, looks like interesting stuff certainly for power electronics

author: DJPhil
author_rank: Frequent Contributor
timestamp: January 10, 2011, 01:20:09 pm
content: Quote from: joelby on January 10, 2011, 12:28:31 pmI do love my leaded solder.Quote from: joelby on January 10, 2011, 12:28:31 pmThat's great news. Once I get squared away again after bills and the like I'll definitely try this stuff out. I'll check with Ultrakeet to see if they can ship to me here in the US, as I like the idea of helping out the birds.Quote from: Simon on January 10, 2011, 12:40:05 pmThat one threw me too. Their website has a link to their'spec sheet'and afaq. The faq says the coating is about 1/10,000 of an inch, so that'd be 0.00001, and the spec sheet says 40-70 micro inches, so I assume that'd be 0.00004 to 0.00007. They talk a bit about durability and the like in the faq, and it looks like the sort of thing that'd stand up well in a power application. It will tarnish in time, but it'll protect the copper in doing so and in turn the outer layer of tarnish will protect a bit of the silver as well.Weird fact of the day. Did you know that silver used to tarnish in the atmosphere much more slowly than it does today? Silver usually tarnishes from exposure to ozone or sulfur compounds, and the increase in the latter released from man made sources have made silver much more quick to tarnish than before the industrial revolution.(sorry, too much coffee)

author: Simon
author_rank: Unknown
timestamp: January 10, 2011, 05:38:48 pm
content: I though that with microns and thou/mils we had enough measuring references without some two bit company coming up with another so 0.000001 micro" = 0.001 thou, which is 0.00254 microns *40 = 0.1016 microns and *70 = 0.1778 so basically 0.1-0.18 microns, wow thats not a lot, no wonder they came up with a new measurement system to make it sound like something you can get your teeth into. Well that's not very thick but hey if it protects, fine and being a better conductor than copper won't cause issues with trapping heat into the tracks like tin/solder would being 10X less conductive

author: am2pgs
author_rank: Contributor
timestamp: January 10, 2011, 08:54:18 pm
content: regarding that cool-amp stuff, I read somwhere (sorry can't remember where) that you could easilly make it yourself with basically silver chloride and salt.My problem is not sure where to get silver chloride or silver nitrate(to make silver chloride) from here in the UK. I'd love to give it a try.

author: Simon
author_rank: Unknown
timestamp: January 10, 2011, 09:29:00 pm
content: to be honest for the price of it I'd rather buy it made up although there is a 18 USD UPS delivery charge, maybe there is a uk supplier ?