Who a beginner need hotair/solder paste to solder these parts? - Page 1
Forum section: electronics / beginners

author: Beamin
author_rank: Super Contributor
timestamp: October 19, 2017, 12:45:13 am
content: So I have the regular hakko chisel tip. I'm good at soldering but surface mount has never been done. When you were first starting out with electronics how would you go about soldering this? Can it be done with simple rosen core solder and the iron? Or do I need to glue down the really small parts on the right (to help as a beginner)?This kit wasn't terrible expensive and I don't even remember ordering it I think I clicked by mistake and it showed up at my house. But I don't want to fuck it up.The youtube tutorial videos I have seen all seem to use hot air guns but I don't have one.Image has a 31 ga 3mm needle a 30 cal bullet and a penny for scale. Those little SMA caps look scary small.As far as the too small to see aspect:I will be getting this awesome 32" wide screen (Almost 4k resolution) video screen magnifier that sits over a X Y axis sliding table and you can adjust colors; B+W; optical and digital zoom; change to invert colors; invert B+W. You can read any color code resistors with it; even ones on blue bodies because you can enhance the colors. You can snap grid lines on the picture too and does UV light and filters. Some how you can see through the pages of a book with it (XRAY vision!) It does more stuff like take pictures that I didn't get to play with while testing today. It costs a lot(!) around $5-6k I think but I think its worth it as a family member is paying for it as an early xmas present. It will be a while until I get it but I'll be sure to make a thread and brag about it.

author: Signal32
author_rank: Frequent Contributor
timestamp: October 19, 2017, 12:54:19 am
content: The capacitors look like 0805 which is huge ( seehttps://www.eevblog.com/forum/beginners/soldered-0805-vs-0603-vs-0402-vs-0201-vs-01005-vs-008004-today-)/msg1134443/#msg1134443 )Ideal way is indeed solder paste + heat air gun.You will still do very good with solder paste + soldering iron.You can get by with resin core wire + soldering iron. I would recommend flooding the pad with liquid flux, holding down the component with tweezers and touching one terminal at a time with soldering iron tip with decent amount of solder on it.

author: John B
author_rank: Frequent Contributor
timestamp: October 19, 2017, 01:12:40 am
content: As an aside note, its good practice to blunt the tips of needles if you're using them for chemical dispensing onto stuff you're working on. Otherwise guns and drugs paints an interesting picture.

author: Brumby
author_rank: Unknown
timestamp: October 19, 2017, 01:18:22 am
content: Using a bullet for a scale reference in electronics is a new one for me... and in Australia is of little help.Quote from: Signal32 on October 19, 2017, 12:54:19 amThis is my advice also.The first thing you will learn is that even the "huge" 0805 packages will dance along your PCB and bench at the slightest excuse - and surface tension will make them respond like neodymium magnets. You are going to need something to hold them in place while soldering. If you are concerned about using metal implements, then a long toothpick is an option.The next is - DON'T drop them. You will never find them unless you are working on a plain, smooth, light coloured surface - and even then it's a "maybe". Carpet is a black hole.

author: Ian.M
author_rank: Super Contributor
timestamp: October 19, 2017, 01:49:28 am
content: For the SMD ICs, tack solder ONE end pin, check alignment, reheating and correcting as required, tack solder the other end pin on the same side then drag solder the opposite side and finally return to drag solder the first side.SeeEEVBLOG #186, for detailed methods.

author: Nusa
author_rank: Super Contributor
timestamp: October 19, 2017, 02:34:40 am
content: There are hundreds of "smd soldering" videos out there. You should be able to find out all about the various ways to do it. Then focus on "smd hand soldering" if that's what you aim to do.Vision equipment is helpful, but these parts are big enough that it's not necessary for most.

author: cdev
author_rank: Super Contributor
timestamp: October 19, 2017, 03:18:20 am
content: I have much better luck using a toothpick to put (very) little dabs of solder paste on the pads on my board and then the parts, and then simply heating it up on a hot plate until it melts, and then turning it off.

author: Awesome14
author_rank: Regular Contributor
timestamp: October 19, 2017, 03:44:54 am
content: Get yourself a couple of dental instruments with tiny tips. Also, get some gluetack or funtack. Put the tiniest piece of gluetack in the middle of the SMD mount. For the soc-8s use a bucket tip and drag is along the pins. It takes a little practice. For the other smds, tack one down with gluetack, and use the dental instrument to put a tiny bit of flux on the ends and solder pads. Hold the part with a tweezers also. Solder and tweezers in one hand, iron in the other.

author: Shock
author_rank: Super Contributor
timestamp: October 19, 2017, 10:51:17 am
content: No hot air required for most smd work. You need an appropriately sized tip though.

author: Beamin
author_rank: Super Contributor
timestamp: October 19, 2017, 01:45:14 pm
content: Quote from: John B on October 19, 2017, 01:12:40 amHAHA. Just things I had lying near by. Most American TV shows compare size to football fields so those caps are about 0.00001 football fields long. You can actually see blood in the tip of the needle. I have to take medication with them so I clean the old ones and use them for gluing and dispensing chemicals.

author: Pedro147
author_rank: Regular Contributor
timestamp: October 20, 2017, 03:24:14 am
content: I do a lot of SMD assembly of quadcopter flight control boards with 0.5mm pitch QFN and 0805, 0603, 0402 passives - huge stuffI started out with a Polyimide stencil and a PID controlled toaster oven which I love but for expediency I have been doing a lot with paste and hot air. I also use a toothpick and apply a very small amount of solder paste which also tends to hold even the passives in place. Gently heat with hot air until it reflows. Too easy and fix any bridging with a good liquid flux and drag soldering technique. I have used paste and iron for passives and legged IC's but QFN cannot be done like that.

author: Beamin
author_rank: Super Contributor
timestamp: October 20, 2017, 11:52:32 pm
content: So it looks like solder paste kapton tape and a small tip is in order. Or wait fr my magnifier to come.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 21, 2017, 04:03:33 am
content: Quote from: Shock on October 19, 2017, 10:51:17 amnormal tip can do the job, just not as nice as in the video..

author: Mjolinor
author_rank: Frequent Contributor
timestamp: October 21, 2017, 10:06:45 am
content: Buy some solder wick before you start, you will need it.

author: Ian.M
author_rank: Super Contributor
timestamp: October 21, 2017, 02:01:08 pm
content: Quote from: Mjolinor on October 21, 2017, 10:06:45 amNot just *ANY* solder wick. It needs to be fresh good quality wick(Chemtronics is one of several respected brands), and fairly thin and narrow if you want to clean up SOIC IC joints with good enough control that you don't have to re-do the whole side. Heavier wick is better when you have removed a part and have a lot of pads to clean and level. If you buy a larger reel, *DO* *NOT* touch the wick with your bare hands before use, dispense it onto a smaller working spool, ideally the soft plastic type that covers the coiled wick apart from the working end, and keep the main reel in a sealed bag, as it will tarnish easily due to fingerprints and atmospheric contaminants, which render it nearly useless. That dusty reel of wick you may have inherited from your grandpa is probably *WORSE* than useless.You'll also need extra flux - I prefer pure liquid Rosin (R) in IPA, and aren't fussy about the brand as long as it dries to a hard light amber residue, but many like gel flux: e.g. Louis Rossman recommends Amtech NC-559-V2 Tacky Flux (genuine, not fake crap off EBAY shipped from China).When wiping a pad, initially apply pressure with the bit *WITHOUT* movement, then wipe away from the track with virtually *NO* pressure. Use extra flux, and always clip back the used stiff part of the wick, leaving a short stiff end with the remaining stiff part no larger than the face of your bit. This initially solder saturated section gives you good initial heat transfer so you don't cook the pad off the board, which can happen if you try to heat a pad with a dry bit through a dry wick.

author: Beamin
author_rank: Super Contributor
timestamp: October 21, 2017, 07:14:41 pm
content: That was way easier then it looks. I just taped the IC down put a lot of gel flux on each side and wiped the solder iron down the side with a drop of solder on it. The flux makes it so that the solder doesn't stick where its not supposed to. I thought I was going to have to solder each individual pin one by one. I haven't tried to do the caps yet but it seems like you just put a solder blob on one side tape down heat then solder the other side. Hardest part is reading the numbers on the chips.

author: frog
author_rank: Contributor
timestamp: October 22, 2017, 01:48:42 am
content: IMO you can do a lot of stuff that you'd expect to be impossible if you can actually see what you're doing. A good optical aid (microscope) will go a long way. As you're probably discovering, you can often get away with a bigger tip than you'd think.Hot air has a lot going for it, but be wary of blowing other parts off the board - get in, do the job and get out again.

author: Pedro147
author_rank: Regular Contributor
timestamp: October 22, 2017, 03:06:52 am
content: Quote from: frog on October 22, 2017, 01:48:42 amI totally agree. Once I got a good optical microscope and could actually see what I was doing, my results are much better and now I am confident doing down to 0402 on double sided boards.

author: frog
author_rank: Contributor
timestamp: October 22, 2017, 04:57:22 am
content: But don't try this with a USB microscope - the latency is far too long.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 22, 2017, 05:05:59 am
content: 0805s seemed intimidating to me at first too, but once you develop some strategies, it's really doable. No need for magnification either, though that might help when it comes to smaller sizes.

author: Beamin
author_rank: Super Contributor
timestamp: October 23, 2017, 01:49:23 am
content: Quote from: Mr. Scram on October 22, 2017, 05:05:59 amI'm just having trouble with these caps going to try super glue in a syringe; the CA- stuff that's like water . Hopefully it will flow through a 31 ga needle.I sent one flying and thought I was crewed until I noticed a black speck on my flux gel tip. It was the part about 5 feet away from where I flung it out.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 23, 2017, 02:04:23 am
content: Quote from: Beamin on October 23, 2017, 01:49:23 amI don't use glue. My method with regular SMD parts is to tin one pad. After tinning that one pad, I add some flux to that pad and put the part on top of both pads with tweezers in the place it should end up. This is the only time a wayward part could escape. A brief touch with the soldering iron remelts the tin. It should cool quickly and afterwards, the part is stuck in place. Now you can do the second pad at your leisure.It's basically what you would do with something like a QFP. Fixating first, soldering it in place after. It's just that the after is only the other pad, rather than many pins.

author: tautech
author_rank: Super Contributor
timestamp: October 23, 2017, 02:07:19 am
content: You don't need glue for SMD passives, flux the pad, hold the passive with tweezers and touch with the iron tip....tacked. If you have the iron set too hot it won't hold bugger all solder that you need to wick into the joint. Solder other end....just don't dwell too long on it as the heat will transfer to the tacked end and melt the solder there too. Touch the first joint again...done. Bent end tweezers I hear are best but the straight fine stainless non-magnetic ones I have work fine.Eyesight can be a issue but a simple Optivisor works well for most without the expense and hassle of additional magnification.I never needed hot air until wanting to do SMD rework, then it's a must !!

author: Beamin
author_rank: Super Contributor
timestamp: October 23, 2017, 02:26:25 am
content: I just spent about an hour soldering 4 caps on. Only to realize I soldered the wrong value. I did use super glue with water out f another syringe to activate it. But that takes just as long. Fuck this. The chips were fun this is tedious without magnification. I am just going to clip the leads real short of through hole parts and use those. It just one of those 30$ ebay scopes and I might have a chip up side down but no way to get it off so all could be for nothing. The flux wipes of the lettering on top and this one chip has no dot.

author: Ian.M
author_rank: Super Contributor
timestamp: October 23, 2017, 02:31:30 am
content: You can get flux core solder as small as 0.3mm diameter, and its certainly worth having some small diameter solder (<0.5mm) of the same alloy as your regular solder or solder paste when you are dealing with small passives and discretes and need to add a controlled amount of solder to a pad or joint quickly to avoid cooking the pad off the board or remelting the tack-joint at the other end.Without suitable diameter solder, there's more fiddling around, and the risk of pad damage or is much higher: If the solder wire is too thick, its very hard to control and you often end up with excess that has to be wicked off, and paste is problematic when using an iron because you have to preposition the right amount, and its very hard to control how much ends up on the pad or joint and how much on the bit, so you are lucky if its right in one shot. When you are using hot air or bulk reflow, that isn't a problem as all the solder in the paste in the immediate vicinity of the pad or joint will end up on the pad or joint.Beware of kits with precisely counted small passives and discretes. You *WILL* loose a few, its virtually unavoidable, and when hand soldering, you may loose some that stick to the soldering bit. While it *may* be possible to quickly scrape the part off the bit, by the time you've cleaned it up, it will have been badly cooked, and you don't know how badly its terminal metallisation has been eroded by the solder so reusing such parts is unwise. There's also a problem with unmarked caps - if one flips away, and you *think* you've found it, are you 100% certain it isn't one of a different value you gave up on finding earlier?

author: Pedro147
author_rank: Regular Contributor
timestamp: October 23, 2017, 02:49:37 am
content: Quote from: Ian.M on October 23, 2017, 02:31:30 amExactlyAnything 0402 or smaller, once you lose sight or grip on it and you "think" that you found it. No way Jose, bin it and grab another one.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 23, 2017, 03:07:37 am
content: Quote from: Pedro147 on October 23, 2017, 02:49:37 amThat's what an LCR meter is for. It's not bad practice to ensure everything works and has the correct values before mounting anyway.

author: Pedro147
author_rank: Regular Contributor
timestamp: October 23, 2017, 03:21:12 am
content: Quote from: Mr. Scram on October 23, 2017, 03:07:37 amDefinitely not bad practise, but also not done in practiseCan you see a board fab house checking each individual passives value. If we cannot trust the QC of what's in the tape, what hope have we got?That's why I leave everything in the tape (which I label on unpacking) until I am going to to use it. Sure I will "decant" them into labeled containers just prior to assembly but that's it.I think I break every rule here in regard to ESD but no problems yetThey are mini quadcopter flight control boards and they all work flawlessly.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 23, 2017, 04:30:03 am
content: Who says anything about board fab houses?If you build for yourself, you can prevent some headaches by testing. Remember that board fab houses test after the fact and simply discard bad boards.

author: Pedro147
author_rank: Regular Contributor
timestamp: October 23, 2017, 05:55:05 am
content: Quote from: Mr. Scram on October 23, 2017, 04:30:03 amAll I am saying is that nobody is going to waste their time testing passives before they use them in a hobby buildHowever maybe I am wrong, it wouldn't be the first time.So who here is doing this pretesting of passives in hobby builds?

author: tautech
author_rank: Super Contributor
timestamp: October 23, 2017, 06:23:53 am
content: Quote from: Pedro147 on October 23, 2017, 05:55:05 amSo we buy strips of SMD caps on tape, little lots of 20 are the most commonly bought as you enter SMD.Some nice Asian has written the value on the tape, will it be correct ?When I knew the future of my hobbyist circuits was to be SMD I already had a junk pile of old boards to harvest SMD passives from but of course you don't have any idea of cap values so I dug deep and got a set of ST3 LCR tweezers.They proved to be much more versatile than I imagined and to this day they are my goto component tester for everything. So now I don't harvest parts on the cheap, still the ST3 tweezers have pride of place as #1 tool for SMD and all PCB fault finding and rework. Despite their initial price, over the decade that I've had them their initial price has proved to be cheap.

author: Pedro147
author_rank: Regular Contributor
timestamp: October 23, 2017, 06:47:40 am
content: Quote from: tautech on October 23, 2017, 06:23:53 amPoint taken and no I would be wary in that case too. I have only been buying from reputable dealers but even then mistakes can happen I suppose.My previous comment about fab houses was just pointing out that any machine assembled boards are not going to have the passives checked prior to assembly and even testing a completed board is no guarantee that every passive is of the stated value is it? When harvesting off old boards you have no choice but to measure the values. I did buy these cheap tweezers but to be honest have never used them much.http://www.ebay.com.au/itm/Tweezers-Capacitance-Resistance-Diode-Test-Tester-Pen-Multimeter-Meter-R-C-SMD-/161595625720?epid=1037823615&hash=item259fd990f8:g:PUIAAMXQdGJRzV8SOf course the ones you have look a hell of a lot better obviouslyI assume that your "real" ones are an earlier version of thesehttp://www.smarttweezers.com/and that price, Ouch. I would be making full use of them too.

author: tautech
author_rank: Super Contributor
timestamp: October 23, 2017, 07:12:08 am
content: Quote from: Pedro147 on October 23, 2017, 06:47:40 amMy ST3's are now updated to ST5, of which there are couple of models and I'd like to upgrade to their top model.Even my old ones do an ESR measurement which I find extremely useful when checking electrolytics as you get the uF and ESR in the same window with a single measurement.A couple years back I grabbed a set of Mastech tweezers, IIRC #8910, I think they are better spec'ed than those you linked but nevertheless they didn't cut it against ST3 so I gave them away.I looked hard at SMD and made the plunge a decade ago, worried as hell if I'd manage it but with a visor magnifier it was easy, so much so that I haven't made anallTH PCB since.Soldering these wee components onto PCB is just the start ( if youcansolder), you have to see the little blighters and hold them on point while doing so. We each have our favoured methodology, mine's been KISS and develop the skills with practice. Ineveruse solder wick as I can't bear to fork out what most robbers want for the stuff instead persevere with a manual sucker that can get everything as clean as I need it if you know how to use it. Flux is another one, until very recently never used, just rely on enough being in the flux cored solder that I use of which could be anything I have around that suits the job, The only roll I know what it is, is some I bought nearly 20 years ago, a low temp silver bearing type that is now saved for special needs.

author: Nusa
author_rank: Super Contributor
timestamp: October 23, 2017, 08:28:01 am
content: Quote from: Pedro147 on October 23, 2017, 05:55:05 amI often end up metering through-hole resistors just to confirm their value. But that's more out of necessity because my color vision isn't to be trusted on reading some of the color bands. Brown and red bands look very similar to me, though in really good light I can tell the difference.

author: Pedro147
author_rank: Regular Contributor
timestamp: October 23, 2017, 08:51:02 am
content: Quote from: Nusa on October 23, 2017, 08:28:01 amIf I ever use through hole I do too and I sympathise and agree with you totally

author: Beamin
author_rank: Super Contributor
timestamp: October 23, 2017, 12:26:58 pm
content: Quote from: Ian.M on October 23, 2017, 02:31:30 amI had a couple caps and resistors get stuck inside the solder ball on the tip. That ruins the parts? One board in this kit is SMD soldered and the other is not. There are 20 of those 2nd from smallest parts to solder with 5 different values. I could see if you just have to solder the chips by why SMD solder one board and not the other? These kits would be great if they soldered all those really tiny passives and just left through holes and chips to do. I suspect it has something to do with saving $0.01 per unit and pawning it off on a foreign customer who will never send it back. These companies will practically suck your dick not to get negative feed back so maybe I will bitch and see if they can send me another board with it soldered. Why would you make a chip without a pin #1 dot and sell it as a kit?I think the trick is to buy that assurance 99 cent warranty plan and have them send you a free unit. That way you get an extra device when that one 0.5mmX1.0mm cap gets eaten by your soldering iron. Think about it because they can't send an extra part for a fraction of a cent they have send you a whole new unit.RadioShack had a "product replacement plan" on all kinds of stuff like cordless phones for 3.99. So 11 months in I would say the phones were broken (take out the batteries of course) and get a brand new model and buy another 3.99 insurance plan. I had a new set of phones/mouse/alarm clock etc. every year for about 10 years all the way until they went out of business.I'm going to buy this 99 cent ebay insurance on everything if it works the way I think it does.

author: Old Don
author_rank: Regular Contributor
timestamp: October 24, 2017, 01:19:09 am
content: Quote from: Beamin on October 23, 2017, 12:26:58 pmAnd I'll bet you wonder why they went out of business.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 24, 2017, 01:24:14 am
content: This is why we can't have nice things.

author: Ian.M
author_rank: Super Contributor
timestamp: October 24, 2017, 01:50:15 am
content: Its also how to get into my Ignore List, so I don't have to remember who is ethically challenged.Your Ignore list is to be found at the bottom of the [Modify Profile] dropdown on your profile page.

author: Pedro147
author_rank: Regular Contributor
timestamp: October 24, 2017, 03:20:58 am
content: Quote from: Beamin on October 23, 2017, 12:26:58 pmWhat so you are one of those guys that thinks the world owes you a living are you?I will contact a seller if they are not living up to what they say you will receive but I draw the line at outright theft. That's just me though obviously

author: Beamin
author_rank: Super Contributor
timestamp: October 26, 2017, 05:24:23 pm
content: Quote from: Ian.M on October 24, 2017, 01:50:15 amRadioShack screwed me over bigtime when I was younger and the store was robbed at gun point while I was working as a cashier. They fired me going home early that day. As far as I can tell they are the ones with bad ethics and I don't mind getting a free phone that costs them 94 cents after what they put me through. I told them multiple times they needed to take precautions at location and install a REAL security camera. They did nothing to save costs. They also didn't pay me my commission that month or that whole weeks pay. FUCK RADIO SHACK AND THE MANAGER that went home early that day making me cover his shift. My coworker got bashed over the head with the butt of a gun and they did nothing but fire them too. As for the company that sold me this kit they have sent me three broken kits and argued with me over email multiple times trying to weasel their way out of responsibility.So yes I consider my ethics top notch and if they try to screw me over I have no reservations about treating them the way they treat other people.

author: Shock
author_rank: Super Contributor
timestamp: October 26, 2017, 06:41:26 pm
content: Quote from: Beamin on October 26, 2017, 05:24:23 pmProbably more believable if you didn't start originally talking about defrauding other sellers via insurance at the start, but good story about the robbery. You need to work on the delivery a little because retribution by deceit is generally not an admired trait either.