Cleaning oxidised soldering iron tips - Page 1
Forum section: electronics / general

author: adx
author_rank: Frequent Contributor
timestamp: January 31, 2020, 12:14:57 pm
content: A bit of a dumb question, but I picked up a Metcal and the tip it came with is so badly oxidised that solder pushes right off (I did manage to ball up a little just to check that it was sort of working, a slight puff of flux smoke). It looks smooth and not pitted or wizzened away through the plating.I've never had a tip get this bad so I don't know the best way to get it clean, if possible. I usually just find a patch that works and chase some solder over it using a combination of scraping and blind ignorance, but this is like some sort of advanced ceramic coating. I was just wondering if there is a 'pro tip' for this sort of thing (other than getting a new cartridge, which I will do anyway, just want to try it / get that one useful). I've tried the goldilocks (brass) and wiping, I may have some tip cleaner around but I doubt that would work on this if I could find it. An acid? Electrolysis? Surface grinder? Space shuttle exhaust plume? Plan A is to sand it under a microscope, but I thought I'd ask in case I'm missing something other than common sense.

author: GromBeestje
author_rank: Frequent Contributor
timestamp: January 31, 2020, 12:28:52 pm
content: There are solder tip activators for sale which are to clean oxidised solder tips. They're called soler tip activator, retinner, refresher. Heat up the iron and dip it in that stuff.https://nl.farnell.com/weller/tip-activator/tip-activator-low-temp-25g/dp/873895https://www.ebay.com/itm/box-Clean-Paste-Soldering-Iron-Tip-Refresher-Resurrection-Plaster-Solder-Cream/174144394309?hash=item288bd09445:g:eXYAAOSwxR1eDvXl

author: adx
author_rank: Frequent Contributor
timestamp: January 31, 2020, 01:38:55 pm
content: Ah! That's what it's called. It's what I meant by "tip cleaner". I always thought it was for people endowed with less blind ignorance than me, assuming it's ordinary solder paste and flux, but apparently it has abrasive. Thanks for the 'tip' - I was searching in the wrong place. I'll find / procure some.Failing that using that search term led me to some useful things on YT: Weller make a thing called a "polishing bar", and there's a video "How to clean Soldering Tip" which has a few tips including steel wool and scraping with a knife, looks like also running it over some saturated solder wick can help which I hadn't thought of. One left-field idea that's just given me is to try to solder to the tip with another (bigger) iron, after a bit of a clean.At the back of my mind is dipping it in some acid.gabinetex, just noticed your reply come in while writing this. Encouraged to hear a process which works. I recently got a kit of sandpaper which goes up to 8000 from Aliexpress - in NZ the finest anyone thinks we need is 1200. I'd better get to bed, and try some of these techniques out tomorrow.The mind does boggle though at how it got that bad. It'd have to be turned on, which implies someone thought it would be useful to solder stuff. I suppose it might be a good way to get controlled small amounts of heat into an SMT joint. Anyway, I've been itching to try a Metcal since 2016 when I had my first horrible experience soldering, after decades of blissful ignorance with (mostly) a Weller PTA7 tip which does everything from 120A connectors to QFPs. In the meantime I got a T12 clone which can do things the Weller can't.Actually not true about my first horrible experience. That was when my parents thought I was going to burn the house down, so I soldered on the back step with a bucket of water next to me. I was so intently focussed on the job that I picked up the iron by the wrong end, and plunged the whole lot into the bucket of water, blowing the element on my shiny new Antex 25W. I must have been using it in meataxe / stabbing mode because the burn was right across my palm, and it was bad. The water definitely helped. Every burn I've received while soldering since then hasn't been so bad, so it could be said a lesson well learned.

author: Shock
author_rank: Super Contributor
timestamp: January 31, 2020, 09:45:10 pm
content: Anything that is a low abrasive will clean it up, that plus elbow grease. It's like polishing a piece of metal, you just have a layer of crap you need to work through to get to the shiny and be patient. If the tip is heavily pitted and old though it might not be worth the effort.Don't be too quick to use a high temp and rosin fluxed solder before the tinned section of the tip is shiny from cleaning as you will just burn on rosin which impede tinning it properly, the idea is use good soldering brass wool and tin the tip a little with solder before wiping clean with brass wool. Eventually you will be able to easily apply solder to the whole tinned section.Also don't be too concerned about anything but a reasonable sized shiny area at very tip end. As you use the brass wool frequently to clean the solder and burned flux from the tip it will eventually polish the rest up over time.

author: richnormand
author_rank: Unknown
timestamp: January 31, 2020, 10:40:07 pm
content: I have the Weller tip activator in the first link from GromBeestje.Used it on my Weller soldering station and it worked perfectly.I don't know if the formulation is optimised for the composition and alloys used by Weller however.It did not seem to damage the tip unlike abrasives could do on the surface plating.

author: adx
author_rank: Frequent Contributor
timestamp: February 01, 2020, 01:11:58 am
content: Some results in:I've worked out "it got that bad". It seems someone had curated a nice impervious layer of oxide ceramic over the sides of the tip, which would help with rework. After a bit of pushing and shoving around (below) the end started accepting tiny patches of solder, and is worn down (it's a sttc-190 0.25mm tip and the end is definitely not that small, also I can see plating missing). So the end was just badly oxidised (and worn), the rest of the tip plating seems to be intentionally beyond hope. I can see how relying on one tiny patch of wettable surface could be useful - you can touch the side of another joint and it won't melt.I also tested "I suppose it might be a good way to get controlled small amounts of heat into an SMT joint." since I've never tried to use a fully-oxidised tip in anger before. It does work, sort of. You hold it there for a few seconds, push it in and wait. A little heat flows and preheats the board. Eventually there is enough in the joint to melt the solder - it seems quite serene and might be good to avoid thermal shock for caps. I was soldering on an old video card with 0402s and some bigger caps. An added advantage is it can get solder to ball up and separate, these balls can then be rolled around and even put back. Might be useful for removing shorts on preheated or hot-air boards. You can also do some interesting polishing and scraping of solder fillets which soften but don't really melt. I tried using the tip like a drill to see if that could improve heat transfer but that's when the oxide came off and spots of solder started sticking. Interesting experiment, but none of this is for me, apart from the idea of putting some high temperature paint on a rework tip to insulate the sides, even that would be messy.I tried scraping with a knife, but the sides absolutely won't wet. There is a fine surface roughness to the plating, 90% of the oxide remains in the valleys and is not exposed by the knife.I then tried a chemical many people might have about the place: A paste of citric acid to dip it in while heating and cooling the tip. Didn't do anything.More experiments to come, but knowing what I know, I may just grind the end of the tip down a little more and keep it for what it seems to have been 'modified' for.The next problem is buying tips for these things. It seems you can only get 600 (626F) and 800 (775F) tips - that's a big gap, why no 700? It could well be that after all this time a Metcal is not for me and a $25 T12 iron is state of the art. But yet to work through that, open mind time. Empty mind even.

author: Shock
author_rank: Super Contributor
timestamp: February 01, 2020, 05:14:03 am
content: STTC-190 is a 700 series tip, they have a confusing numbering convention5XX = 500 series = 575F/302C0XX = 600 series = 675F/357C1XX = 700 series = 775F/413C8XX = 800 series = 925F/496CYou can see why people think their Metcals are performing really well, 700 or 800 series is operating at a fairly high temp. The STTC-190 conical tip kinda sucks so perhaps it's for the best that it's toast.Edit:Which exact model and handpiece did you get anyway?

author: adx
author_rank: Frequent Contributor
timestamp: February 01, 2020, 12:47:50 pm
content: Handpiece? Hmm, it looks most like MX-RM3E, no words I can see. It is plastic and quite thin - seems nice.Ah those temps make more sense. I was possibly comparing Thermaltronics advertising 330C with Metcal's 775F, hence my numbers which seem to miss 700 entirely after a little bit of rounding. I was thinking of trying the 600 series first anyway, because 775 deg F is just too hot in my book.I did tests once with Weller tips and demonstrated 800 lifting pads off FR4 where the 700 didn't at all. My boss / client then changed over to 700, having come from a factory where I used to also work and everything was 800 - for speed. Tips basically on fire all the time, didn't last long, but for repetitive production work where people know exactly what they're doing it's fine. Engineers mashing at air wired sculptures and flicking off 0805s (all we had in the day), not so much. Maybe Metcal worked out that backing off just a bit is good enough. There was a competing school of thought (a person) who was pushing 600 tips across the board, arguing even 700 is too hot, he was right of course, but 600 was impossibly slow. They had an extremely expensive Pace, and it was horrible (to me), I don't know why. I quickly found Weller PTA7 to be the obvious compromise.I am also struggling to find a Metcal 600 tip in the shape I want - without the hot end on a long stalk. Shorter cone (but not the very short 4mm ones available) with flatter end. Thermaltronics do make a more conical chisel M6CH016, nowhere to be found though.I was / am starting to wonder if Metcal is a (reluctant and incorrect use of the word...) s c a m. Because of these marketing-hot numbers, and advertising suggests the heat is directly in the tip, appearing just below the surface, where it's needed. Which it's not, as far as I can gather. There's a copper core some way (not far) down the shaft which has the curie point material around that, and a coil. But that's the basic arrangement of the Weller WTCPS irons, except the curie material is in a blob at the end of the core rather than around it. And thermal contact (heater) is much better in the Metcal, so faster response and less overshoot (if that matters). Maybe that's why the old Wellers have always treated me so well. Undoubtedly Metcal is better, and was the only thing even remotely in that class in its day, but it either was partly based on skilful marketing manipulation back then, or some of the magic hasn't translated through the decades. But not seriously suggesting s c a m, it's obviously a nice system and the proof of the pudding is in the heating. Yet to have my snack though.Wo ok essay stop.