Learned a rookie 101 (temperature) soldering lesson today - Page 1
Forum section: electronics / beginners

author: Electro Fan
author_rank: Super Contributor
timestamp: May 31, 2020, 05:40:39 am
content: Several years ago I purchased a Weller WESD51 soldering iron. I don't do much soldering and it seemed to work "ok" (good not great) - so when I saw a deal on a Hakko 888D a couple years later I decided to give it a try. The Hakko seemed to heat somewhat faster and while the controls weren't super intuitive in some respects they were more user friendly than the Weller - or maybe the Hakko manual was written a bit better.Anyway, both irons were ok but neither really gave great results. Using all Kester solder, both leaded and lead free, in typical temp ranges nothing seemed to heat up or melt the way I expected, and sometimes wire insulation would melt more than I would have liked. I chalked it up to infrequent rookie soldering skills.I questioned the temperature displays on the two irons so along the way I got out my Fluke DMM with it's thermocouple. The DMM showed such a large discrepancy compared to the two irons that I figured maybe the DMM was much more accurate for volts, amps, and ohms than degrees (although theoretically they should be somewhat related). The discrepancy was so large I just didn't believe the Fluke.About a year ago I purchased a Hakko RST FG-100 thermometer. It came with some sensors but I purchased two extra sets - one that claimed to be official Hakko sensors (I was a little skeptical) and the other set that I think acknowledged they were clones or compatible (it was a while back, so I don't remember for sure on that). Anyway, today I finally tried out the RST FG-100 and the sensors.The first thing I found was that all 3 sets of sensors seemed to agree with each other. No discernible differences among the 3 sets of sensors. Having gained some confidence in the consistency of the sensors I then checked the Weller iron and the Hakko iron against the Hakko RST FG-100 thermometer. Neither iron was even anywhere in the ballpark of the Hakko thermometer. The displays on the irons indicated that they were each MUCH hotter than the what the RST FG-100 showed - but I decided to go with the Hakko thermometer as the reference. So I dug out the manuals and tried to get both irons to agree with the RST FG-100. (Following the instructions and getting the Hakko adjusted was easier than adjusting the Weller.) After some back and forth I got each iron close to what the RST FG-100 said was the correct temp.Next I did some simple soldering and what da ya know? Soldering behaved MUCH more like expected. For temperatures that made sense the solder flowed easily as expected - no waiting for unreasonable periods of time and no overheating.So, next I dug out the Fluke and it's thermocouple and what da ya know? The Fluke came within within about 1.5% of agreement to the Hakko iron and within 3% of agreeing with the Weller iron.Moral of the story, if you haven't checked your iron temp against some thermometer that you trust, you might be soldering with a temperature pretty far off from what your iron indicates (assuming it has a temp display).

author: Ian.M
author_rank: Super Contributor
timestamp: May 31, 2020, 06:52:08 am
content: Yes. There's a 'sweet spot' temperature range for any particular combo of solder alloy, flux and 'weight' of work, outside of which soldering rapidly becomes difficult or even impossible.If you don't have a soldering iron thermometer, load up the bit with a blob of a known eutectic solder alloy, and check the displayed temperature it solidifies at, then re-melt it with the smallest possible temperature increase to do so. A wooden toothpick to prod the blob with may help detect when it starts to solidify or melt. Compare with the alloy's specified melting point and adjust calibration accordingly. You should be able to get it within +/-5 deg C at the melting point which should put it well within a +/-10 deg C error band at the significantly higher bit temperatures used in practice, which should be good enough for all except the most critical and demanding parts and processes. N.B. wipe off and refresh the solder blob between measurements to remove burnt flux and oxides and minimise errors.

author: Electro Fan
author_rank: Super Contributor
timestamp: May 31, 2020, 09:18:59 pm
content: Ian.M, ThanksFrom reading your posts I know you are on top of soldering (among other stuff). So a little bit off the (temperature) topic, but a few questions...1) What is the likely shelf-life of solder if it's properly stored? Does it differ if it's lead vs lead-free (is one likely to last longer)? Or maybe other ingredients (amount and type of flux, RA, etc) also are determinants? Any general guidelines or it varies widely by ingredients?2) I've read that solder likes a fairly cool storage environment (maybe 32F- 50F?). If it's stored in a garage that ranges from ~45F - ~85F (winter to summer), how much would you think that might accelerate (shorten) shelf-life?3) How would you describe the characteristics of shelf-life roll-off? And is the roll-off in performance enough that you would recommend replacing solder at some rule of thumb interval to get better soldering performance, or would you suggest just dealing with some degraded characteristics during the solder-making process and be happy to have joints that will still continue to reliably conduct electricity? Or aside from a degraded soldering experience during the soldering process, is there a point at which the joints themselves will be so degraded from expired or expiring solder that it will impair the integrity of the solder joints?

author: Ian.M
author_rank: Super Contributor
timestamp: May 31, 2020, 10:15:19 pm
content: https://www.eevblog.com/forum/beginners/solder-shelf-life/https://www.eevblog.com/forum/beginners/does-solder-really-expire/https://www.eevblog.com/forum/beginners/cored-solder-not-behaving/TLDR: For solder wire, the alloy doesn't change or degrade with age. The flux core *may* degrade with moisture and age, or even attack the surrounding alloy, but degradation of rosin R, RMA and RA flux cores is insignificant over many decades. Surface oxidisation can be a problem as it uses up a proportion of the flux core when the solder melts, eventually overwhelming the available flux. Oxidisation will be worse if stored at high temperatures, high humidity, or if exposed to air-borne pollution, salts or acid fumes. However even if you've got badly oxidised solder, cleaning off the oxide by pulling it through a folded over green panscourer, then kitchen paper wetted with IPA till it no longer leaves a dirty oxide streak will restore close to original solderability.Solder paste is a different matter. The small particle size and liquid flux allows the flux to slowly attack the solder particles + the solvents in the flux tend to evaporate. If stored at room temperature (rather than refrigerated) it is likely to go bad well before its official expiry date.

author: tggzzz
author_rank: Super Contributor
timestamp: May 31, 2020, 10:31:13 pm
content: These professional video tutorials clearly show how soldering works well, and fails, and how and why.https://www.youtube.com/playlist?list=PL926EC0F1F93C1837Note that they teach you to get it right by observation, not by setting a dial and hoping.Those videos are succinct and make full use of the mediumandthat most precious quantity:your time. The only problem is the way the narrator mispronounces solder.

author: Electro Fan
author_rank: Super Contributor
timestamp: June 01, 2020, 12:35:47 am
content: Quote from: Ian.M on May 31, 2020, 10:15:19 pmThanks for the links. I've read them all just now. Doesn't sound like many people are staying awake at night worrying about their solder's shelf-life.

author: Electro Fan
author_rank: Super Contributor
timestamp: June 01, 2020, 12:38:28 am
content: Quote from: tggzzz on May 31, 2020, 10:31:13 pmThanks! I just watched the first video. It is an outstanding introduction to solder and soldering for electronics! I'm looking forward to watching the rest of the series. Thx again!

author: tggzzz
author_rank: Super Contributor
timestamp: June 01, 2020, 07:33:38 am
content: Quote from: Electro Fan on June 01, 2020, 12:38:28 amThey illustrate the abysmal quality of most yootoob vids!

author: exe
author_rank: Unknown
timestamp: June 01, 2020, 08:04:16 am
content: Wow, didn't know that Kester, Pace, etc so long in business. I'm watching the first video, and it's superb.

author: Shock
author_rank: Super Contributor
timestamp: June 01, 2020, 01:53:27 pm
content: On the Pace Worldwide channel there are a few different series - Basic Soldering for Electronics, Adventures in Repair, Rework and Repair in Electronics.

author: Cubdriver
author_rank: Unknown
timestamp: June 02, 2020, 03:44:57 am
content: Those Pace videos are excellent. I wouldn't worry too much about the shelf life of wire solder (at least wire solder from a reputable manufacturer). I'm currently using a spool of Kester 44 60/40 thatheI got at an old job some time in the mid-late 80s and it is just fine.-Pat<edit - I need to proofread better - have no idea how "I" became "he">

author: tggzzz
author_rank: Super Contributor
timestamp: June 02, 2020, 07:16:50 am
content: Quote from: Cubdriver on June 02, 2020, 03:44:57 amSo am I, also without problems.Solder paste is a different issue, though.

author: Electro Fan
author_rank: Super Contributor
timestamp: June 03, 2020, 08:03:11 pm
content: Don't want to go off topic too far but since we roamed from solder-shelf life to how to solder and back again, and since it's a thread I started maybe we can stretch the topic a bit further.I'm a safety first guy and definitely don't want to start a big solder (lead vs lead-free or anything else) debate but today I asked my wife if she had some red nail polish so I could mark a transistor that had failed so I could come back later, find that transistor and study the failure mode.I don't have this calibrated to the nano, micro, or even milli-smell but I'd say if solder fumes on a scale of 1-10 are about a 2-3 after half an hour of soldering, the nail (toe too?) polish is about a 7 after 30 seconds. (I'm leaving 8 for hospitalization, 9 for near fatal and 10 for fatal). YMMV

author: jmelson
author_rank: Super Contributor
timestamp: June 04, 2020, 12:27:01 am
content: Quote from: Electro Fan on June 03, 2020, 08:03:11 pmSome things that smell **AWFUL** are not really that harmful. Check out methionine and butyric acid. And, of course, there are things that have no smell at all (carbon monoxide) that can kill you with milligrams.If you are sensitive to solder flux, it can be a real problem. I've been soldering for at LEAST 55 years, and really don't have any problem with it. You do want to wash your hands after handling solder (especially with lead) before eating.Jon

author: exe
author_rank: Unknown
timestamp: June 04, 2020, 08:22:32 am
content: I recently studied that fumes from rosin flux are considered toxic. Too bad since I'm quite used to it, and I like it. There is one piece of information is missing: how its toxicity compares to other fluxes. Does anyone have any information? I found nothing.The reason I'm asking is to get an idea how toxic it is in "absolute" scale. May be it is toxic comparing to fresh forest air, but but completely normal comparing to an air in a dense urban area. Anyway, I try to be careful now and avoid breathing any fumes, just in case.PS some fluxes cause me headaches after even short exposure.