Why are these so hard to solder ? - Page 1
Forum section: electronics / general

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 07:52:24 am
content: So ...eBay Chinese Arduino Nano - checkPin headers - checkFibre glass pen to clean pads - checkFlux pen (eBay cheapie) - checkGenuine Hakko soldering iron - checkClean genuine Hakko chisel tip - checkMG Chemicals leaded 63/37 solder - checkIron at 380 C - checkFailure to flow properly - checkI eventually got to the point shown in the photos but I had to really load the solder on, attack with the iron from all angles, use nice braid to take off the excess and at the point where all the pads had been wetted, add enough solder for tidy joints.I've had the same with Pi Zero pin headers.Why does it go this way ?Everything else that I solder goes very well, smooth flowing and shiny joints.

author: Rerouter
author_rank: Super Contributor
timestamp: July 16, 2016, 07:59:31 am
content: at a guess your pin headers are slightly corroded and your flux isn't up to snuff, also 380 is way hot for normal solder, i rework must bigger beasts using a hakko 888 at 330,

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 08:05:00 am
content: Quote from: Rerouter on July 16, 2016, 07:59:31 amYes, it could be the flux (as per my eBay mention). That did still make a difference though.I used to use eBay solder too and then tried the MG stuff. It is infinitely better. Same with solder wick. So, I have considered better flux before but with shipping rules over here, we're talking an arm and a leg once a courier is factored in.http://www.ebay.co.uk/itm/MG-Chemicals-8341-10ml-No-Clean-Flux-Paste-Syringe-/322189997186?hash=item4b04053482:g:vS0AAOSwpDdVa3LjI wonder if it would be worth it.Regarding the pins, yes they look a little dull but the solder wasn't flowing on the pads, not the pins.Thanks

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 08:08:11 am
content: They also have this for the same price. However, my pen tips get wasted when working with through hole component leads.http://www.ebay.co.uk/itm/MG-Chemicals-Liquid-Rosin-Flux-835-P-Pensize-/222131634310?hash=item33b813c086

author: Rerouter
author_rank: Super Contributor
timestamp: July 16, 2016, 08:11:13 am
content: personally i have never used a fibreglass pen so i cannot speak for them, however based on your images the pads look to have reflowed fine,One remark i will make is if you are using a hakko 888D (common one beginners end up with), make sure you read the manual and check its calibration, every few months another worker will try and set the temperature on that model and end up mis-calibrating the iron instead where i work,the cheap thermocouple your multi meter likely came with is good enough for this task, lightly tin the tip then hold it against the iron and note the temperature, (you will likely be within 15 degrees or so)

author: IanB
author_rank: Super Contributor
timestamp: July 16, 2016, 08:21:08 am
content: Quote from: netdudeuk on July 16, 2016, 08:05:00 amYou're in the UK; surely you don't have to import things to obtain good quality? It must be possible to obtain good quality flux and solder from within the EU without hassle?The MG brand is common in the USA, but I would not go to the trouble of having it shipped over from there if it is not marketed locally.

author: CJay
author_rank: Super Contributor
timestamp: July 16, 2016, 08:24:26 am
content: I've found the Chinese are able to manufacture packs of unsolderable pin headers, or at least headers that aren't easy to solder.I use a Weller W60 (plenty of heat capacity, not heat, subtle difference) and genuine Ersin Multicore 60/40, the headers solder but not as nicely as the ones I buy from UK suppliers (even Maplin).Weirdly, the headers that came with the Arduino Pro mini nano uno duo treize whatevero I buy from China always solder, so far, really easily.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 08:24:34 am
content: Quote from: IanB on July 16, 2016, 08:21:08 amI got the solder from Circuit Specialists who are also based in the UK.Check out the screen capture to see where the cost gets so high. I think that this is due to UK regulations.£16.73 for a flux pen ?

author: Rerouter
author_rank: Super Contributor
timestamp: July 16, 2016, 08:26:42 am
content: try a tack flux syringe, they are about the same in costs, but you get far more milage, and it holds things in place at the same time.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 08:31:15 am
content: I've just compared an eBay Chinese Arduino Pro Micro with an Adafruit EZ-KEY, both plugged into the same breadboard.The joints on the latter are all super shiny and beautifully shaped. The Arduino joints are ok but not so good in both respects.Maybe it is a combination of better pins and pad quality ?

author: CJay
author_rank: Super Contributor
timestamp: July 16, 2016, 08:31:53 am
content: Wow. Find a local source perhaps, that's a ridiculous handling charge, I can buy all manner of chemicals form eBay that need 'special' handling and the carriage isn't anything like that.However, if you like, I will coil up a couple of metres of the 60/40 Multicore solder I have here so you can try it and post it to you if you PM me your address.

author: sleemanj
author_rank: Super Contributor
timestamp: July 16, 2016, 08:32:54 am
content: +1 on the cheap paste flux syringe.Reduce iron temp a bit, 320 would be more typical, you might be boiling off the flux too fast.That said I've always found headers a pita to solder generally speaking but lately I have been using a J type (aka hook, bent) tip and that makes for an easier job of it - orient strip perpendicular to you, start at the top, get the pin in the nook of the hook feed solder into it between the point and the pin, drop down to the next pin...

author: CJay
author_rank: Super Contributor
timestamp: July 16, 2016, 08:35:08 am
content: Oh, and just to add, unless I've been hot air reflowing SMD I've *never* needed more flux than that contained in the cores of the solder or paste.

author: IanB
author_rank: Super Contributor
timestamp: July 16, 2016, 08:47:08 am
content: Quote from: netdudeuk on July 16, 2016, 08:24:34 amI've no idea about that shipping and handling charge. That's crazy. I would expect a flux pen to be shipped within the UK in a padded envelope by first class post.Also, I second the recommendation of Ersin Multicore solder. It's the best solder I have ever tried.Try to find out from other UK forum members where they get their supplies from.

author: CJay
author_rank: Super Contributor
timestamp: July 16, 2016, 08:54:35 am
content: Quote from: blueskull on July 16, 2016, 08:44:21 amI was kind of joking about unsolderable headers as I've not found any that wouldn't solder with some effort, the bag I got from eBay that are not easy to solder but as you say, the tinned ones and the gold plated ones solder really easily.I'd not increase iron temperature unless I was using lead free solder, the flux in the 60/40 just burns and leaves an unholy mess to clean up.

author: stj
author_rank: Super Contributor
timestamp: July 16, 2016, 09:43:36 am
content: you have stacked mistakes here.first you shouldnt use flux, because you have it in the solder and different fluxes can mess with each other.second, you should use decent lead-free solder like Stannol TC with HS10 or KS115 flux in it.(rapid sells it, and lots of fluxes and other good stuff)https://www.rapidonline.com/stannol-ks115-sn99-cu1-rosin-free-halide-activated-synthetic-resin-solder-wire-520183third, your temp is way to high.i use 330 to solder with lead-free, if your temp is too high it will burn the flux and make things worse instead of better.all fluxes have a maximum working temp - your iron is way over.

author: Rerouter
author_rank: Super Contributor
timestamp: July 16, 2016, 09:47:40 am
content: Why would you recommend lead free solder to a beginner? Its far more toxic and harder to use than normal leaded. ?

author: stj
author_rank: Super Contributor
timestamp: July 16, 2016, 09:49:54 am
content: where did you get that info from?tin/copper is cleaner than tin/leadthe modern fluxes hardly fume, they pool as a liquid on the joint - none of that white smoke that leaded solder with rosin flux gives.as for ease, if your temps are right, you wont notice any difference with tin/copper solder.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 09:50:50 am
content: Quote from: Rerouter on July 16, 2016, 09:47:40 amBeginner ? I got my first iron and built my first radio forty two years ago

author: Rerouter
author_rank: Super Contributor
timestamp: July 16, 2016, 10:00:21 am
content: Sorry the nature of the question asked and the information provided led me to think that way.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 10:02:30 am
content: Quote from: stj on July 16, 2016, 09:43:36 amThanks for the reply.However, the solder wouldn't flow on the (burnished) pads until I'd used the flux pen.I'd also say that the MG Chemicals solder is a decent solder. It usually produces bright smooth joints, as per my comment above about the Adafruit boards with their own headers.Here's what I use -http://www.circuitspecialists.eu/leaded-solder-wire-roll-0-635mm-dia-454g-sn63-pb37-4884-454g/http://www.circuitspecialists.eu/leaded-solder-wire-roll-0-81mm-dia-454g-sn63-pb37-4885-454g/I work at 280 degrees C virtually all of the time but it wouldn't flow until I turned it up.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 10:06:09 am
content: Quote from: Rerouter on July 16, 2016, 10:00:21 amNP. I'd probably put it down to a cheap board and (probably) headers too but I'm always interested in how others got on with things like this.Here's an example of someone making a mess of soldering a Pi Zero. I'd say he'd be better off with a proper iron with a better tip.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 10:25:21 am
content: Ok guys, so I took some eBay Chinese headers and an eBay Chinese FR4 board, used the same solder at 280 degrees C and used no additional flux.Here's what I get, which I think is pretty reasonable given I've not even cleaned off the flux yet. So, I'd say cheap headers can be ok. Cheap Arduino boards are not so good.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 10:26:30 am
content: I'll just add that they just flowed. I didn't need to move the iron from one side of the pad to the other or spend ages there with the heat.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 10:36:46 am
content: Quote from: blueskull on July 16, 2016, 10:31:42 amAgreed. However, in this case, it looks pretty much like for like.

author: Monkeh
author_rank: Super Contributor
timestamp: July 16, 2016, 10:41:28 am
content: Quote from: stj on July 16, 2016, 09:43:36 amBecause leaded solder just doesn't work. It was never any good, we had no problems switching to lead-free in industry...QuoteThis has been hashed out before, and I'll be blunt: Bollocks. Yes, 380C is fairly hot, no, it is not 'way too high'. It may make a mess of some fluxes if you're slow about it, but it's not a big problem.Respectfully, someone who solders at around 380C using leaded solder practically every day without issues.

author: tautech
author_rank: Super Contributor
timestamp: July 16, 2016, 10:56:49 am
content: Quote from: netdudeuk on July 16, 2016, 10:26:30 amThere's very little in my life I've been unable to solder with the correct flux cored solder. Never needed additional flux if the solders flux has been correct for the job, in fact I never use additional flux.I have at least 4 solder types, all leaded and some have more active fluxes than others.Get a leaded solder with an active flux for the odd time you'll need it, just a small spool will be the ticket.

author: GreyWoolfe
author_rank: Unknown
timestamp: July 16, 2016, 12:37:35 pm
content: Quote from: netdudeuk on July 16, 2016, 10:06:09 amI would say that he would be better off letting someone who has a clue what they are doing take care of it along with the proper equipment. That was painful to watch.

author: janoc
author_rank: Super Contributor
timestamp: July 16, 2016, 12:59:13 pm
content: Quote from: GreyWoolfe on July 16, 2016, 12:37:35 pmConsidering that hot poker he was doing it with, with no flux added, I would say he has done a reasonable job. Not great, but I have seen people do much worse.If you want to really cringe, watch some episodes of the Ben Heck's show. He has much better gear, but his soldering is atrocious.

author: System Error Message
author_rank: Frequent Contributor
timestamp: July 16, 2016, 01:03:12 pm
content: If in the UK and you dont want to buy overpriced stuff look at certain websites. Circuit specialists is one when it comes to supplies and there are many other websites, some of which have a UK version of a US or other country website where you can purchase electronics supplies for a good price. Avoid ebay because its easy to get stuff that isnt up to standards and things that arent what they are rated.Some things like soldering tips you can actually cheap out on. When you're soldering look at the temperature for it. 220C is sufficient for many solder while some will need much more temperature.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 01:11:05 pm
content: Quote from: janoc on July 16, 2016, 12:59:13 pmI agree. I really like a lot of things that he does but when I see his so(l)dering, I think the same.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 01:12:33 pm
content: Quote from: System Error Message on July 16, 2016, 01:03:12 pmThat's where I got my solder from.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 16, 2016, 01:14:46 pm
content: QuoteYes thanks, my solder has a 'RA Flux Core'.

author: Buriedcode
author_rank: Super Contributor
timestamp: July 16, 2016, 01:44:42 pm
content: I too have encountered difficult-to-solder pin headers. It isn't the flux or solder that's the problem, its the pins themselves. Generally, ones from Farnell, Rapidonline, or RS are fine - whether gold plated or not, they are all plated with solderable metals and happily wick solder, leaded or lead-free. However, those that seem to be on mass-produced boards - Arduino, Rpi and all the sub boards for them, as well as just bulk buys of pin-headers from Ebay tend to use cheaper ones that I don't think are plated very well.It ends up looking like one is trying to solder those enameled wires (not the solderable kind) - lots of flux bubbling, it gets hot, but just doesn't 'take' at all. So whilst I'm not exactly sure 'why', for arduinos and Rpi stuff, I just use sockets instead. And when buying pinheaders you don't have to go to the expensive route of Samtec or Toby, Rapid or Farnell are fairly cheap. I'll admit its annoying but as China produces a huge range of quality - people will always tend to buy the absolute cheapest for their boards.

author: stj
author_rank: Super Contributor
timestamp: July 16, 2016, 03:05:26 pm
content: Quote from: Buriedcode on July 16, 2016, 01:44:42 pmyour wrong, it's the wrong flux in your solder.if you want to solder onto nickel,brass or a number of other materials then your flux *must* contain Halide.if it's Halide-free then your f'd.

author: nanofrog
author_rank: Super Contributor
timestamp: July 16, 2016, 05:53:05 pm
content: Quote from: netdudeuk on July 16, 2016, 08:08:11 amI'd suggest getting theMG Chemicals 835 in a 100ml bottle. Not only does it work well, but it's far cheaper this way vs. disposable pens, and you can choose whatever method for dispensing you wish (dip a small artist brush, nail polish bottle w/ brush, refillable brush pen such as aBonkote BON-102*, needle bottle, ...).BTW, the store is located in the UK.It can only go by ground shipping, and they use NEP or Yodel (can't go by Royal Post). Hopefully the shipping rate will be reasonable since you're in the UK.* If you use eBay or similar, expect a counterfeit where the pump mechanism is usually DOA (you can remove the guts, but if you do, keep it upright or it will leak out).Real Bonkote flux pens aren't exactly cheap, but work extremely well IME as you have the ability to control just how much flux goes where you want it. Well worth the additional expense IMHO.

author: Buriedcode
author_rank: Super Contributor
timestamp: July 16, 2016, 06:02:31 pm
content: Quote from: stj on July 16, 2016, 03:05:26 pmJust tested it with multicore 5 core epsin 362. Halide activated, temp ~ 340 (normally I set it to 360 when I'm banging out long lines of pins). Managed to get a small amount of solder on one side of one pin. I still just blame the pins, but not complaining, I added some onto an order from a generic ebay shop selling 'modules', just binned the rest.

author: boffin
author_rank: Unknown
timestamp: July 16, 2016, 07:09:29 pm
content: Quote from: nanofrog on July 16, 2016, 05:53:05 pmAmusingly I drove by the MG Chemicals HQ yesterday. I wish they sold stuff there, rather than having to drive across town and hope someone has it in stock

author: Brumby
author_rank: Unknown
timestamp: July 17, 2016, 02:37:52 am
content: Quote from: GreyWoolfe on July 16, 2016, 12:37:35 pmWhen he asked if his soldering was perfect - I was well ahead of him on his answer ... but one thing caught my eye a bit further along.....

author: stj
author_rank: Super Contributor
timestamp: July 17, 2016, 02:55:11 am
content: loland high brightness led's (for a few seconds)

author: janoc
author_rank: Super Contributor
timestamp: July 17, 2016, 01:32:50 pm
content: Quote from: stj on July 16, 2016, 03:05:26 pmI would rather say those are wrong headers for the job, if they are nickel plated (or plated with some other unsolderable metal), not a wrong flux.I have encountered some headers like that, but it was usually because they use very cheap plating that doesn't do a good job against oxidation. The seller had them also stored who knows where for who knows how long, so then this happens. Either toss the headers or, if you really have to use them, roughing off the oxides using a a fine sandpaper or scraping with a knife usually helps and the solder will take.However, unless the OP doesn't use correct temperature and technique, it won't help any. 380C is way too much, even for lead free solder. At that temperature any flux will vaporize and burn off instantly, with no effect on the solder. In addition, the OP doesn't use extra flux, making the problem worse.

author: bktemp
author_rank: Super Contributor
timestamp: July 17, 2016, 01:54:51 pm
content: Quote from: janoc on July 17, 2016, 01:32:50 pmIt depends on the solder. I use lead free solder with a recommended solder temperature of 380°C (EDSYN SC1250). I tried a lower temperature and the result looked ugly, so you have to use the high temperature for the flux to work correctly. For other lead free solders 380°C could be way too high, so always read the datasheet.

author: Monkeh
author_rank: Super Contributor
timestamp: July 17, 2016, 01:59:08 pm
content: Quote from: janoc on July 17, 2016, 01:32:50 pmReally? Wow, I had no idea my flux does nothing so my solder never works. All those good joints are, apparently, total junk.

author: donotdespisethesnake
author_rank: Super Contributor
timestamp: July 17, 2016, 05:11:51 pm
content: Quote from: Monkeh on July 17, 2016, 01:59:08 pmI think you need to check your reading comprehension.

author: Monkeh
author_rank: Super Contributor
timestamp: July 17, 2016, 05:14:28 pm
content: Quote from: donotdespisethesnake on July 17, 2016, 05:11:51 pmReally? So he's not saying 380C is so hot the flux won't do anything?How, exactly, do you parse that?

author: m98
author_rank: Frequent Contributor
timestamp: July 18, 2016, 04:18:53 pm
content: Quote from: janoc on July 17, 2016, 01:32:50 pmYou know that the temperature at the joint can be much lower than the set temperature of the station due to high thermal mass of the target?

author: rrinker
author_rank: Super Contributor
timestamp: July 18, 2016, 06:02:53 pm
content: Quote from: stj on July 17, 2016, 02:55:11 amMaybe the project is a flashbulb emulator? Or a DED burner.

author: tautech
author_rank: Super Contributor
timestamp: July 18, 2016, 08:37:14 pm
content: Quote from: m98 on July 18, 2016, 04:18:53 pmThis very simple statement ^^^.Dissimilar thermal mass of the 2 parts of a simple solder joint is a real trap for learners until soldering experience is gained and to overcome it can be as simple as extending the "soak" time to allow the solder enough time to wick completely around the joint.

author: Monkeh
author_rank: Super Contributor
timestamp: July 18, 2016, 08:43:06 pm
content: Quote from: tautech on July 18, 2016, 08:37:14 pmAnd this is why the specific temperature of the tip isn't that critical. Merely that it's hot enough to reach the desired temperature of the workpiece, and cool enough not to violently oxidise. And before someone tries that tack, no, 380C is not so hot the tips wear out rapidly.Excessively low temperatures can actually cause you to spend too much time trying to heat the entire joint, cooking the contact point..

author: janoc
author_rank: Super Contributor
timestamp: July 18, 2016, 09:58:35 pm
content: Guys, the OP was talking about solderingheadersand complaining that the solder wasmelting fine but not "taking"(aka not wetting) the pin. That's hardly a situation of something with a high thermal mass. Or are you commonly soldering a strip of those to a ground plane? So yes,in that situationthe iron was too hot, burning off flux.

author: Monkeh
author_rank: Super Contributor
timestamp: July 18, 2016, 09:59:49 pm
content: Quote from: janoc on July 18, 2016, 09:58:35 pmIf too much heat was the problem, I'd never get solder to stick to the tip. But, oddly enough, the flux activates normally and solder adheres to the tip.Excessive heat is not the problem.

author: stj
author_rank: Super Contributor
timestamp: July 19, 2016, 03:19:03 am
content: think what you want, this isnt religion.a smart person would just try several times at say 320,340 & 360 and compare the difference.if using lead solder then best to start at 280 and work up.**all good discovery's come from doing experiments - not from writing theory's [Nicola Tesla]

author: Monkeh
author_rank: Super Contributor
timestamp: July 19, 2016, 03:27:38 am
content: Quote from: stj on July 19, 2016, 03:19:03 amNo, it's cold hard fact.QuoteSure, let me just find the temperature knob on this... Hmm, nope, just the power switch. 'fraid it doesn't go down to 280C at all.There are certainly fluxes which react badly to higher temperatures, but most don't have a problem, and soldering at higher temperatures doesn't automatically cause problems.

author: jh15
author_rank: Frequent Contributor
timestamp: July 19, 2016, 05:36:22 am
content: "In Tesla's age, making anything new is a major breakthrough. In nowadays, making things to work while it fails in 2 years is considered fail."Doesn't the fruit named company goal want everyone to replace their stuff in 18 months?

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 19, 2016, 06:34:43 am
content: Quote from: janoc on July 18, 2016, 09:58:35 pmSorry if it wasn't made clear but the solder 'blobbed' on the pins. It went on there ok. The solder wouldn't flow onto the pads. That's why I mentioned cleaning them with the pen.

author: batteksystem
author_rank: Regular Contributor
timestamp: July 19, 2016, 09:52:56 am
content: Quote from: Rerouter on July 16, 2016, 09:47:40 amCertainly not more toxic for lead free solder (comparing to 40% lead one)

author: batteksystem
author_rank: Regular Contributor
timestamp: July 19, 2016, 09:59:26 am
content: Quote from: tautech on July 16, 2016, 10:56:49 amAlso using a flux too aggressive can "de-solder" the component, I don't mean the solder will melt but rather the component will fall off, literally.

author: TheAmmoniacal
author_rank: Unknown
timestamp: July 19, 2016, 10:00:15 am
content: Anyone know if it's possible to solder on pure silver?

author: TheAmmoniacal
author_rank: Unknown
timestamp: July 19, 2016, 10:02:20 am
content: The book "Principles of Soldering" says:Fluxeshave been formulated that are satisfactory formost pure metals and alloys, including stainlesssteel. Noted exceptions are beryllium, chro-mium, magnesium, titanium, and some alumi-num alloys, which are classified as “unsolder-able” in air, unless coated with a different metal.

author: TheAmmoniacal
author_rank: Unknown
timestamp: July 19, 2016, 10:13:17 am
content: Quote from: blueskull on July 19, 2016, 10:11:22 amThanks!

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2016, 10:15:44 am
content: Quote from: batteksystem on July 19, 2016, 09:59:26 amNever seen that other than in arc or gas fusion welding of dissimilar metals, and I've done a good amount of all including roofing soldering (acid flux), brazing, gas silver soldering, copper silphos (pipework), Tig, Mig, arc AC, DC and reverse DC, oh and of course electrical soldering.Give me a specific real example of a toooooo aggressive flux.Oh yeah, it might be the wrong flux for the job.

author: matts-uk
author_rank: Contributor
timestamp: July 19, 2016, 10:50:48 am
content: Quote from: netdudeuk on July 19, 2016, 06:34:43 amThe most common cause of solder refusing to whet is oxidation, or some other contamination, of the surfaces. Burnishing may make things worse as the striation increases friction and surface area, and traps residues.During cable and header assembly, you should (always) pre-tin mating surfaces before trying to solder them together. Whet the surfaces and overload with solder, then use a de-solder pump or braid to remove the excess, leaving a shiny layer of solder, only a few molecules thin. Gold plated contacts in particular, should always be pre-tinned - Otherwise the Gold dissolves into the solder, contaminating the joint at the molecular level.If your iron and technique are not sufficient to whet and pre-tin surfaces before assembly, obviously you need to sort that out before trying to solder the final assembly.The dwell time on your so called, 'thermally balanced' iron is working against you, I am afraid. 380C is  the temperature of the tip, left idle for an hour, in free air, at room temperature. As soon as you bring the iron in contact with the cooler joint surfaces, the temperature will fall faster than the element can raise it. As PCB assembly tools, these irons are notorious for being simultaneously -Too hot for the flux and too cold for the solder.You _need_ additional flux, as the initial high temperature melts the flux in the solder core, which pours out and is flashed away, before the solder melts.The best you can do is tin the tip, bridge the pin and pad, feed the solder in directly opposite. When (if) the solder starts flowing, pause until it drops into the VIA then continue to feed in solder until the pad is full and there is a convex fillet to the pin. The dwell time is almost certainly long enough for sufficient heat to conduct as far as the plastic former, to melt it - In which case, you can use a damp (solder iron) sponge or old bread board as a heat sink on the opposite (non solder) side of the header.Finally. Even with a decent iron, the pads connected to the Nano's ground plane and Voltage regulator traces, can be a right ole bitch. I suspect they might use dead horse to glue the copper cladding to the substrate. Maybe flour and water on the really cheap boards.HTH

author: Ian.M
author_rank: Super Contributor
timestamp: July 19, 2016, 11:45:56 am
content: 380 deg C is within the 'ballpark' for hand soldering with normal 60/40 Sn/Pb solder. Weller fixed temperature 'magnastat' irons generally came with 700 deg F (370 deg C) bits as standard. 600 deg F (315 deg C) bits were a P.I.T.A, requiring excessive dwell times on any except the lightest tracks and components. As the O.P. is using a genuine Hakko iron & bits, it should have decent power delivery to the bit so could probably be turned down to 350 deg C, as eutectic Sn/Pb has a lower melting pont than 60/40. However, one does need a reasonable excess over the 183 deg C melting point of eutectic Sn/Pb to get enough heat transfer fast enough to minimise the dwell time.One suspects the PCB manufacturer has a plating or storage problem with the pads. Electroless Tin cam have a shelf life as low as 9 months, and if its a really cheap & nasty manufacturer they may have simply electroless Nickel plated them, (the first step of ENIG so they just skipped the Gold), and cheap Nickel plating is notorious for its poor solderability. The problem is compounded if it or the underlying copper has a high Phosphorous content.There have been occasional reports of fake flux pens on Ebay, that look like the real deal but are filled with stuff that is minimally effective as a flux. The odds of trouble are higher if the fake flux claims to be water washable or no clean. Even lump Rosin dissolved in Meths or IPA, with no added activator is better than that crap.If you get solder balling and refusing to wet the pads, STOP, desolder and disassemble. The *ONLY* hope is to pre-tin the pads and you'll need to do whatever it takes to wet them. A good start is to clean them with a fibre-glass abrasive pencil, then try with good quality active flux core solder + extra liquid rosin flux painted onto the pads and allowed to dry before soldering. If that doesn't work, you may need to actually sand the pads with fine Wet&Dry paper, and use acid flux. Once you've got them tinned, you need to scrub off all acid flux residues to reduce the risk of corrosion. Re-flux with liquid Rosin flux and solder with normal RMA flux core solder.If the pins themselves are unsolderable, its seldom worth trying to get solder to 'take' as the insulator strip holding the header together will distort due to the long dwell time, and its a PITA to get all four sides of each pin clean enough to take solder. Reject as not fit for purpose and replace from a reputable supplier.

author: Buriedcode
author_rank: Super Contributor
timestamp: July 19, 2016, 12:05:14 pm
content: Quote from: Ian.M on July 19, 2016, 11:45:56 amThis. They're so cheap anyway its worth finding, and sticking to, a half decent manufacturer. I Order them in the thousands fromhttp://www.rapidonline.comas they are pretty damn cheap, but never fail. I'm sure some might used very expensive ones which is fair if its for industry but for small runs or hobbywork, no need.