Trying a different brand of solder.  Flux smells like burnt plastic.  Normal? - Page 1
Forum section: electronics / beginners

author: Whales
author_rank: Super Contributor
timestamp: August 07, 2016, 05:26:45 am
content: MBO "AUTOFIL RT 15". According to the datasheet, flux is "Blend of rosin and modified rosin".I melted a little bit on my tip, took a test whiff and it made me start coughing. It smells nothing like rosin, but does smell like burning plastic.Any comments/advice?EDIT: More backstory, photos and details below.

author: jpanhalt
author_rank: Super Contributor
timestamp: August 07, 2016, 05:34:14 am
content: The datasheet doesn't give much more information than you present. Does the flux work? If so, try not to smell it.JohnEdit: The datasheet lists the halide concentration as "nil." If accurate, the flux is not an acid chloride.

author: Whales
author_rank: Super Contributor
timestamp: August 07, 2016, 06:12:34 am
content: Quote from: blueskull on August 07, 2016, 05:33:02 amI have never used this brand before nor heard of it. It was the cheapest lead free on RS-online.Quote from: blueskull on August 07, 2016, 05:33:02 amQuote from: jpanhalt on August 07, 2016, 05:34:14 amI have never dealt with anything that smells this bad, but I don't know if I've used an acid flux before. Are acid fluxes particularly smelly/evil?Quick tests and comparisonNew solder appears really rough after I use it. Here are some joints on tin-plated board, even after trying to fix them up with a block of rosin:I still have a few centimeters of my last brand of lead-free solder left (it was ~1/2 the price of this new stuff). I made some joints on some uncleaned bare copper (a difficult to solder scenario) to compare this new stuff to what I used to use:I had a lot of difficulty getting the joints to wet with the new stuff. Too little did nothing, the only way to get the joint working was to put too much on. My old stuff fared much better (and smelt much better!) even though I didn't completely wet the top joint.Normally I clean my copper before soldering, but this was to highlight how different they feel when making a joint.

author: Whales
author_rank: Super Contributor
timestamp: August 07, 2016, 06:30:57 am
content: Some more backstory on this solderI bought of roll of it from RS-online a while ago (item 555-301, their website is down at the moment).Datasheet.It cost me $21.10 (equates to $211 per kg).They sent me the wrong item (I ordered 0.7mm diam, they sent 1.0mm). I emailed them, didn't get a reply, so I called them a few days later and was asked to resend the email. Within a few hours I was notified of the item being re-shipped to me (for free).The wrong item arrived again. I took more photos and sent another email. At this point it looked like they had the products barcoded incorrectly (both rolls of solder arrived in a bag with the item code + barcode for the correct 0.7mm product).Again, no reply for the past week. I'll ring them tomorrow and see if I can sort it out.My old solderI used to use this stuff:http://www.wagneronline.com.au/lead-free-solder/april-2016-new-products/new-products/6568/fl/It's about 1/2 the price and has worked well for me. It also smells like actual rosin.I've been suspicious that it might not actually be lead-free, because I don't know any methods of verifying it, but thedatasheetsuggests otherwise.Is there a chance that this is actually rosin cored solder?At this point I'm tempted to ask RS for a refund. It behaves poorly, smells completely wrong, they've sent me the wrong item twice and it is twice the price of a competitor.

author: wraper
author_rank: Unknown
timestamp: August 07, 2016, 06:56:15 am
content: It contains only 1.5% of flux which is very low, therefore requires tighter soldering process control than usual solders with about 3% flux content. Also may be inappropriate for the jobs where more flux is required. Your crappy protoboard on the second pic might be one of those because no decent finish, not even hasl. Advantage of low flux content is that less flux residue will be left. IMO learn how to solder properly, adjust soldering iron temperature.

author: Whales
author_rank: Super Contributor
timestamp: August 07, 2016, 07:36:01 am
content: Quote from: blueskull on August 07, 2016, 07:24:22 amThanks blueskull. I've only ever used the one make of lead-free previously and it comes out much shinier.

author: Ian.M
author_rank: Super Contributor
timestamp: August 07, 2016, 08:03:59 am
content: As Wraper has pointed out, there isn't a lot of flux in the core of that solder. I wouldn't expect good results with 60/40 on bare copper with that little flux, let alone when using lead free. The smell isn't indicative of much - burning pine indicates Rosin, but a modified rosin could easily smell like plastic. I've encountered solder with flux that had fumes that smelt like floral air-freshener, which was more irritating than the normal rosin fumes. The whole workshop refused to use the 'romantic' solder!R.S. aren't going to f**k up and supply non-ROHS solder falsely labelled as ROHS, nor will they do business with a supplier that is likely to. Métaux Blancs Ouvrés appears to be E.U. based (although they do have a Chinese subsidiary) and offer solder-bath analysis services so I would expect their solder composition to be as specified. Commercially available lead test swab kits will detect lead oxides and other salts on a metal surface, so if you are still feeling paranoid, get a test kit from a hardware store and compare your 'good' solder, the suspect solder and some 60/40, by swabbing the surface of each in wire form.Are you able to check your actual bit temperature? A type K thermocouple, with the junction in a blob of solder on the bit will give a reasonably accurate result. If you are running too hot, the flux will be burning off before it has a chance to work. See MBO's site for recommended temperatures.As you are soldering bare copper, you should try the solder with some decent liquid rosin flux. If you don't have any good liquid flux you can make a little to experiment with:Crush a little of your rosin block - a piece the size of a large pea should be about right, and add a couple of ml of Isopropyl Alcohol (or if you don't have any IPA, at a pinch you can use methylated spirits). Let it stand overnight in a small tightly sealed glass jar. Apply with a small brush to the pads and let it dry a couple of minutes before soldering.Unactivated pure rosin in IPA flux (or commercial Rosin (R) in alcohol flux that fully dries) can be applied to a whole board after cleaning the copper and allowed to dry to maintain solderability for months. In all except the most critical applications, if a thin film is thoroughly dried, you can treat it as a no-clean flux.

author: Whales
author_rank: Super Contributor
timestamp: August 07, 2016, 09:23:47 am
content: Thanks for the tips. I'm aware of how to making soldering to bare copper easier -- as per my post, I was using the 'hard soldering' situation to highlight the difference between this new solder and my old stuff.I didn't realise the new solder had a significantly lower flux content. Thankyou for pointing it out.I do have a type K and I've been keeping the soldering iron as low as I can. Even after I apply significant external flux the joints still appear cloudy/rough, but they do then wet.QuoteI use metho: if you keep it permanently in a jar then you don't have issues with solubility. Otherwise it's very slow to dissolve.It's especially nice when you get it on your fingers. Nice and stickyQuoteI was referring to my previous solder from a different supplier.QuoteAbsolutely nasty! I'm having trouble physically tolerating the smoke from this stuff, although a fan on my desk does help.I'll atleast talk to RS about making sure they fix up their stock RE wire diameters.Hopefully I'm not going to get more people telling me how to solder properly as soon as they see the bad joint demonstration photos

author: jpanhalt
author_rank: Super Contributor
timestamp: August 07, 2016, 09:50:11 am
content: Your problem may be the solder. SAC solder is expensive, and alternative called K100LD is considerably cheaper and presumably behaves like the older leaded solders.I am still able to use 63/37 leaded solder, but here is a comment from a user of the K100LD :http://forum.allaboutcircuits.com/threads/best-way-to-solder-what-solder-to-use-please-help.122312/#post-981441 (post #5). Maybe your older, cheaper solder was not SAC.As for the smell, "burning plastic" is completely uninformative to me. There are many plastics available today, on one way to distinguish between them is to do a "flame test." The corrollary of that is that burning plastic can have many different odors. Some smell sweet, some buttery, some acrid, some like burned skin, and so forth.Here's a link to Kester K100LD that hopefully will work:http://www.kester.com/download/K100LD%20Lead-Free,%20Silver-Free%20Alloy%20Bar%20Solder%20Data%20Sheet.pdfJohn

author: wraper
author_rank: Unknown
timestamp: August 07, 2016, 10:30:06 am
content: Quote from: Whales on August 07, 2016, 09:23:47 amIMO this solder just showed the lack of skill which wasn't so apparent with other solders and/or not properly regulated temperature. Low flux amount will burn very fast and is becomes very important how you apply it to the joint. Likely you don't preheat the joint with soldering iron before applying solder, probably apply the solder onto the soldering iron, not directly onto the solder joint. Also still using solid rosin is oldscool and weird. Not something that you should be using nowadays, especially if want good results.On the green protoboard there is too much solder applied. Brown protoboard apparently have oxidized and probably even corroded pads by the looks of it. That is the type which I avoid to buy because they are crap.If you still think that your soldering skill is fine, then most likely it is not the case. When I worked in manufacturer authorized mobile phone repair shop in the past, out of about 15 technicians my skill was the only one which I would call decent enough (much better right now). All others didn't know how to solder properly, and I don't think more than a few of them realized it themselves.BTW leaded solder wets the joint and flows much better than lead free. Dull joints are what you normally get with most of the lead free solders.