My First: Surface Mount! - Page 1
Forum section: electronics / beginners

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 09:03:20 pm
content: Greetings all.I thought it would be funny to share my very first surface mount soldering.It started off very well indeed. I ordered some 0805 size resistors and capacitors, a SOIC8 package for the LM2675 and some other random components with the intent of building a Portable 5V/1A USB dual-output charger. The parts arrived and I was shocked at how small they were compared to the through hole components I have been used to for such a long time.Next, I downloaded a free copy of Eagle. Designing my circuit in this wasn't working because none of the components I had were in the library. Either I had to draw them myself (which was impossible using Eagle) or go back to my tusty copy of ExpressPCB. Since the UI in Eagle is so counterintuitive, I decided to opt for designing the circuit in the far superior (in terms of the UI) ExpressPCB.Once the board was finished, etched and polished up for soldering, I attempted to use a sharp-tipped soldering iron to solder the components into place. I found out quickly that the solder tended to make a blob of solder up the soldering iron tip, making it impossible to solder the components. I went back to the larger tip and tried the swipe method several times on the SOIC8 package. ALL of the pins were shorted. I then got a small flathead screwdriver and scraped furiously inbetween the traces to break the shorts. Soldering the SMT capacitors was insanely difficult, because the plastic kept melting. I had to put a HUGE blob of solder onto the board, heat it up and then lay the capacitor prong into the molten solder until it sank in and became wedged in place. The SMT diode was a ballache, as the two bottom pins were both anode and the backing plate was the cathode! I used the giant molten blob method on that too, pressing it down with needle-nose pliers so it stuck into place.What a ballache SMT is to solder using an iron!Next time I'll invest in some solder paste and a small oven to let them cook in instead.Hope you have fun looking at the photos.P.S. It actually works. It produces 4.969V on the output and charges my phone. I did test it before plugging in my phone to make sure it wasn't going to blow it up!

author: SeanB
author_rank: Super Contributor
timestamp: April 27, 2015, 09:07:38 pm
content: Buy a bottle of flux or a flux pen, that will make the work easier.

author: CrashO
author_rank: Unknown
timestamp: April 27, 2015, 09:17:46 pm
content: Yeah, Flux is the way to go.I regularly solder SSOP packages with a normal 2.5mm chisel tip. Apply some flux (using a pen or gel), melt a piece of < 0.4mm solderwire to the tip. I usually add about half the tip (so just over 1mm) of solder. Touch the pads with the tip, and voila

author: nanofrog
author_rank: Super Contributor
timestamp: April 27, 2015, 09:27:09 pm
content: Quote from: SeanB on April 27, 2015, 09:07:38 pm+1Would make a world of difference.BTWjim_griff, what are you using for solder wire (type of flux & amount of it)?

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 09:34:01 pm
content: Quote from: SeanB on April 27, 2015, 09:07:38 pmQuote from: CrashO on April 27, 2015, 09:17:46 pmYeah, I was regretting not buying a flux pen when ordering the components.Quote from: nanofrog on April 27, 2015, 09:27:09 pmI'm using some Tin/Copper solder (99.3%/0.7%) with flux in it, but the flux burns off before I manage to get it onto the board. Probably better to just get a flux pen, as mentioned above.EDIT: I can't stop laughing at those photos! It's just such a nooby job!

author: npelov
author_rank: Frequent Contributor
timestamp: April 27, 2015, 09:34:38 pm
content: The shorts were not a problem of the soldering iron. I bet you will have as many problems with oven. Watch Dave's videos about soldering. It's important to use a lot of flux. I use soldering paste (flux paste, doesn't have any tin in it) Cynel like this one:http://www.retroamplis.com/Cynel-soldering-grease/flux-40g. It's probably not meant for SMD, but it's cheap, doesn't made damage if you don't clean it and it does the best job for the price ($1-2). Proper flux would probably do better.So get the paste/flux, put tons on the shorted pins and drag the iron tip between the two pins. Then if it doesn't work clean the iron and try again. If there is too much solder - usesolder wick, flood it with flux/paste and suck the excessive solder.QuoteMe too, but I use 1.5mm. I find it easier to reach some places and I don't like changing tips. Mine is slightly damaged from 2 years of usage, but I still soldered 20 pin SSOP last week. Watching videos helped me a lotP.S. the url ofthe soldering pastewas wrong. Fixed it.

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 09:39:46 pm
content: Quote from: npelov on April 27, 2015, 09:34:38 pmI need to invest in a new soldering iron, to be honest. It is great for Lead solder but piss poor for SnCu solder. Doesn't get quite hot enough. I'd be better with a temperature controlled one instead.

author: tautech
author_rank: Super Contributor
timestamp: April 27, 2015, 09:43:14 pm
content: The type and thickness of solder you are using will have a huge influence on success.For hand work don't piss around with any Pb free muck, use a quality leaded solder.A pointed iron tip should do the job, SMD components that you describe have a small thermal mass.That said, tinning of the tip is critical, you should NOT have blobs of solder anywhere but on the very end of the tip and small blobs at that. Get some tip cleaning brass or SS wool.I've yet to need additional flux for any SMD work, just lightly tin one pad first, position component with tweezers and re-melt tinned pad. Done. Then solder remaining pads/leads.

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 09:49:49 pm
content: Quote from: tautech on April 27, 2015, 09:43:14 pmThe tips are too clean so the solder tends to blob up the tip due to surface tension. I'm going to let it heat up for an hour to damage the tip and clean only the first 1mm of it with tip cleaner. That should prevent the solder from blobbing any further up the tip. And yeah, I need to get some leaded solder.

author: nanofrog
author_rank: Super Contributor
timestamp: April 27, 2015, 09:51:48 pm
content: Quote from: jim_griff on April 27, 2015, 09:34:01 pmWould you happen to know what type of flux (i.e. R, RMA, RA, or no-clean), and how much of it there is (stated as a percentage by weight, letterPfollowed by a number, orCorefollowed by a double digit number)? Brand?Since you mention fast boil-off, what temp were you using?Could be there's just not enough flux in the solder wire, poor quality flux, you had the iron set way too high, or some combination.

author: tautech
author_rank: Super Contributor
timestamp: April 27, 2015, 09:55:40 pm
content: Quote from: jim_griff on April 27, 2015, 09:34:01 pmThere's your problem above.Get an incandesant light dimmer and cool your iron down a bit, another trick was to put a bulb in series with the iron, switched for hot or cooler.

author: Howardlong
author_rank: Super Contributor
timestamp: April 27, 2015, 09:59:03 pm
content: As well as what others have said regarding using full fat solder, flux etc, the good news is that when doing a board without solder resist it will always look a bit rubbish, the solder always flows where it's not needed.

author: tautech
author_rank: Super Contributor
timestamp: April 27, 2015, 10:06:17 pm
content: Quote from: jim_griff on April 27, 2015, 09:49:49 pmNooooo, don't do that, get some temp control for your iron, it's too hot and flashing the flux away.

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:08:58 pm
content: Quote from: nanofrog on April 27, 2015, 09:51:48 pm"Shen Mao® Lead-Free Solder"Composition: Sn 99.3%, Cu 0.7%Diameter: 1mm~Made in Taiwan~That's all the information about the solder. It's some cheap stuff I bought from Maplin a few years ago.Quote from: tautech on April 27, 2015, 09:55:40 pmIt actually doesn't get hot enough to melt the solder very well. I think it doesn't contain much flux in the first place and/or it's the wrong type.

author: JackP
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:11:50 pm
content: How are you soldering passives? Don't put the solder on to the iron, melt the solder on to one pad, then melt that and position one end of the component on the pad. Then solder the other end normally.

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:13:25 pm
content: Quote from: JackP on April 27, 2015, 10:11:50 pmI'm usually holding the passive in place and putting the soldering iron onto it with a small blob. It's the only way it works. My iron doesn't get hot enough to be able to touch-melt solder once it's on the board. I have to tin the tip so it allows for better heat conductivity to the solder on the board, else it takes about 20 seconds to start melting. I need temp. control on my iron, to be honest.

author: JackP
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:17:18 pm
content: What power rating is your iron? Doing it that way will mean the flux burns of regardless of temperature, so the solder won't wet on the joint, or will result in an unreliable joint. This can be resolved with flux, but it is a waste really. My £20 Hakko 936 clone can do it well enough.

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:19:54 pm
content: Quote from: JackP on April 27, 2015, 10:17:18 pmIt's an Antex XS25 (25W) Iron. I see your point about the flux. I think it'd be best for me to get some Lead solder and a flux pen to be on the safe side until I'm more experienced. Through-hole is a piece of piss for me, but SMT is just...haha.

author: tautech
author_rank: Super Contributor
timestamp: April 27, 2015, 10:26:46 pm
content: Quote from: jim_griff on April 27, 2015, 10:19:54 pmIt shouldn't be a problem really.Ditch that Pb free muck and you'll be amazed at the difference.Sure if you have all the good gear and you have a methodology that works for the muck use it, but for hobbyists and hand populated prototypes, rework and such STAY away from the crap. It'll just give you gray hairs before your time.

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:29:34 pm
content: Quote from: tautech on April 27, 2015, 10:26:46 pmI ran out of my Lead solder a few weeks ago. It gives me a headache when using it (even in a well ventilated area), but man is it easy to melt! Stuff just solders/desolders without issue.

author: tautech
author_rank: Super Contributor
timestamp: April 27, 2015, 10:38:11 pm
content: Quote from: jim_griff on April 27, 2015, 10:29:34 pmNot all do, it may have been the flux type used, get a different brand.I keep 3 solder types, low temp(Silver alloy), agressive flux and an easy clean mild flux.The problem with hobbyist soldering, particuliarly SMD, by virtue of the operator's close proximity, convection of the heat from your body draws the fumes up past your head and we breathe the fumes.Any small draft to prevent this happening is beneficial.

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:41:12 pm
content: Quote from: tautech on April 27, 2015, 10:38:11 pmI put a 120mm computer fan inside a cardboard tube and that draws away the fumes quite effectively now. Even with it 20-30cm away, it still sucks the fumes away quite well. Can't beat homemade stuff.

author: nanofrog
author_rank: Super Contributor
timestamp: April 27, 2015, 10:56:26 pm
content: Quote from: jim_griff on April 27, 2015, 10:08:58 pmFirst off, this stuff is crap. Get some good quality solder in a lead based alloy.I'd suggest looking for Sn63Pb37 (also written as 63/37), with 3.3% by weight of RA solder (may also be written as P3 or Core 66), at 0.020"/0.5mm diameter from a company such as Multicore (Henkel), Kester, Alpha (Cookson), AIM (American Iron & Metals), or Indium for general purpose use (great for both new & old work).[Quote from: jim_griff on April 27, 2015, 10:08:58 pmSwitch solder as recommended above, and this will improve (lead based has a lower melting point than the lead-free alloys).

author: jim_griff
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:59:25 pm
content: Quote from: nanofrog on April 27, 2015, 10:56:26 pmThanks! I'll give that a try. Haven't tried many different types of solder since this 0.5kg stuff has literally lasted years.

author: VK5RC
author_rank: Unknown
timestamp: April 28, 2015, 03:50:45 am
content: I would support the smaller diameter solder, too much solder, either too big a diameter solder or not getting enough heat onto the pad/component, bizarrely sometimes a bigger tipped soldering iron (better heat transfer) can work better. Also clean the board before soldering eg isopropyl alcohol.Practice, practice practice. In a decade or so I might get my smd soldering good! HiHi

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: April 28, 2015, 03:47:36 pm
content: I bought 50$ of soldering supplies. An old used digital iron, multicore desoldering braid and solder, electrolube flux and thats it. My first job was a repair of a 6ch. reciever that uses surface mount class D amplifiers. It has a 0.65mm pin pitch and it worked on the first try! Thanks dave for the suggestions on brand name stuff. WELL worth it. Also, if you have .7mm dia solder, you can load it into a 0.7mm mechanical pencil. Bit more precise.

author: Howardlong
author_rank: Super Contributor
timestamp: April 28, 2015, 03:54:55 pm
content: Quote from: jim_griff on April 27, 2015, 10:13:25 pmYou definitely need a better iron if it won't heat the pad up enough so you can flow a bit onto the pad. And do yourself a favour and get some full fat solder. I don't understand why Maplin don't sell it these days.Applying solder by putting it onto the iron first is a no-no as others have said, the flux will have burned off before it hits the pad for a start.

author: IanB
author_rank: Super Contributor
timestamp: April 28, 2015, 04:41:51 pm
content: Going to echo lots of previous comments here.1. Don't use lead free solder for hand soldering. Always use tin/lead solder (63/37 or 60/40).2. Solder doesn't ball up on a clean tip. If solder makes a ball you have dirty surfaces or insufficient flux.3. The Antex XS25 tends to run hot. No way is it "not hot enough".4. If you can't melt solder within a second of touching the iron to the joint, it's not a temperature problem it's a dirt problem. Clean surfaces with IPA and then add liquid flux before soldering.5. If you melt capacitors you are taking far too long to solder them. The iron should be touching for 2-3 seconds at most. Clean the pads, use liquid flux, clean the iron tip better. Make sure the iron tip is shiny before you start making a joint.6. A good technique for SMD soldering is to place the solder wire between the joint and the iron. This way the iron will melt the solder, which will then conduct heat into the joint, which will flow to form a fillet. Watch tutorial videos for a demonstration.

author: Electro Fan
author_rank: Super Contributor
timestamp: April 28, 2015, 07:11:43 pm
content: Two questions/requests:Any links to preferred flux (liquid or otherwise)?Any links to especially good videos on Surface Mount soldering techniques?Thx

author: IanB
author_rank: Super Contributor
timestamp: April 28, 2015, 07:36:05 pm
content: Quote from: Electro Fan on April 28, 2015, 07:11:43 pmHere's an expert at work:https://youtu.be/5uiroWBkdFY

author: JackP
author_rank: Regular Contributor
timestamp: April 28, 2015, 08:04:28 pm
content: I've seen that before, shows great methods that aren't shown in most tutorials. If you haven't, check out Dave's tutorial on the subject, IMHO MOST others are generally flawed in some way, but Dave shows good technique along with step-by-step instructions; you know someone is not lying to you when they leave in their mistakes for you to learn from (and gives justifiable reasons for them, like not having practised). He also has some hot air and oven reflow videos out there.

author: tautech
author_rank: Super Contributor
timestamp: April 28, 2015, 08:31:09 pm
content: Trouble is most people have a wide range of kit and little of it may be well suited to SMD work.Then general soldering experience has a lot to do with success.If one thinks they will do a good amount, best they bite the bullet and get a rework station.Get a couple of chisel or hoof tips and one I find very handy from time to time, the 45 degree knife tip that can bridge 2 pads on many passives. Great for rework.But hang on to your big old iron, just yesterday I needed it for modding leads from a ATX PSU where a dozen leads came from one pad. Even the hot little Antex like the OP's wasn't up to that task.

author: nanofrog
author_rank: Super Contributor
timestamp: April 28, 2015, 10:54:28 pm
content: Quote from: Electro Fan on April 28, 2015, 07:11:43 pmMG Chemicals Rosin Flux 835is a reasonably priced, quality RA flux that comes in hobbyist friendly sizes.Quote from: Electro Fan on April 28, 2015, 07:11:43 pmPACE SMT Video DatabasePace Inc. SMD soldering and desoldering(10 lesson playlist from Marc Siegel's YouTube page).

author: miguelvp
author_rank: Super Contributor
timestamp: April 29, 2015, 03:13:07 am
content: Quote from: IanB on April 28, 2015, 07:36:05 pmWeird that @0:55s they don't mention flux and they are indeed using it.

author: savril
author_rank: Regular Contributor
timestamp: April 29, 2015, 11:10:18 am
content: Contrary to previous comments, I don't agree with some of the Pb free bashing. I agree than 10 years ago, Pb free was much harder to use than lead solder but things have changed. I did my first SMD soldering few weeks ago (after 10 years without soldering) with Pb free solder and it went relatively easy, up to 0603 and SSOP (if I forget 2 pad lift).But I was in a better condition of success than you :I used rosin flux (and it really help a lot, especially for ICs)I have a quality solder (with Ag), much easier to use than the Pb free I had 10 years agoI have a temperature controlled ironFrom comments I had seen in this forum, this trio seem to be the condition to Pb free quality soldering.However it ask for a certain amount of money (Ag is not cheap). If you can't get these, it's probably better to get lead solder... But more important, use flux. It really helped me a lot.A temperature controlled iron is probably a good investment too. As SMD have a lower thermal mass, they can burn more easily.There is also the fact that the PCBs I used had a solder mask which can help. For my first SMD soldering, I used a 1,2 mm chisel tip for components and a 2,2 mm for drag soldering ICs. If you get pins shorted, just apply more flux and drag the solder to the outside, so easy with flux.