Smd Soldering Help - Page 1
Forum section: electronics / beginners

author: Ranger14
author_rank: Regular Contributor
timestamp: February 25, 2018, 02:47:28 am
content: I am starting to work with smd parts and hoping I can get some suggestions.1-What kind of paste flux do you prefer2-What kind of tips should I be getting for my FX-888D for smdThanks

author: tautech
author_rank: Super Contributor
timestamp: February 25, 2018, 02:54:19 am
content: Quote from: Ranger14 on February 25, 2018, 02:47:28 amHow small do you want to go ?2.4mm chisel or hoof tips are preferred and usable down to 0603.K (skew) tips are good for passive rework as they can bridge to both pads.Few use paste for hand work on SMD, fine solder wire is good enough. I've never bothered using finer than 1mm but many do. If you go to small SMD you will want thin solder.A flux pen is of great help, I never bothered with one for ages however I'd recommend a SMD newbie get one.

author: Teledog
author_rank: Regular Contributor
timestamp: February 25, 2018, 04:50:20 am
content: To each, their own ..everyone has their own preferences.Would use the finest tips possible for your ironWas taught at the last company..for passives anyway..Rosin flux pen swiped on the pads of a new clean PCBTouch the pads with your finest tip iron..with thin leaded rosin core solder, make the tiniest dots possible on the pads.May take a bit longer with grounded padsSwipe the solder dots with the rosin pen againPlace the SMD (again, we're talking passives here) components on top/balanced on the solder dots (they should stick)Ideally, use two soldering irons with the fine tips and solder simultaneously with the two irons..you can manipulate them while hot, it takes practice.With only one iron, use tweezers & hold it/press down as you alternate heating from pad to pad.Do not drink too much coffee!For multiple pin ICs..flux the PCB, place one "dot" of solder on a pad, preferably not a ground, and flux again.Place the IC, hold it with tweezers, press down slightly and touch the leg/pin with the iron to tack the leg..make sure all the pins/legs are aligned, (it would not hurt to flux the remaining IC legs/pins) & finish soldering the restMy 2 cents anyway...

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: February 25, 2018, 05:04:29 am
content: Personal preference. With that said, I'd suggest going for a cheap Hakko compatible tip kit from eBay, something like this:https://www.ebay.com.au/itm/10-PCs-Soldering-Iron-Station-TIPs-Rework-Solder-Lead-Free-FOR-hakko-FX-888-T18/271581080528?epid=716161960&hash=item3f3b7e6bd0:g:aVQAAMXQpwFRbN2HThey arenotofficial Hakko tips, and I do recommend always using official tips (if you can afford them). However, this would be a good way to "sample" all the different types to find out what feels best for you.Personally, I've found that the "angled blade" (type k) to be the most useful, especially for large LQFP packages.http://www.hakko.com/english/tip_selection/type_k.htmlAlso, the trick is to use aLOTof flux.

author: Ranger14
author_rank: Regular Contributor
timestamp: February 28, 2018, 03:29:27 am
content: Wow thanks for all the great information ..My I plan on soldering mostly 1206/0805 and sot-23 packages.. The cheap tip package on ebay is a great idea and will have to pick one up..Also I tried liquid flux and found it to be messy and a pain for me to use..So I was going to Flux paste and was looking for suggestion on company makes good flux paste like MG Chemicals,Chip Quik and so forth?? Oh has anyone every use paste in a can flux from chinaThanks

author: KL27x
author_rank: Super Contributor
timestamp: February 28, 2018, 03:56:11 am
content: T18-CF3. If you look up "John Gammel" on youtube, you'll find some videos of SMD soldering that looks easy. And in fact, it IS that easy. He calls out the Hakko CF3 as "an amazing SMD soldering tip," and it is one of my favorites. The C means it is a hoof tip. The F means that it is tinned-face, only. The 3 is the diameter of the face in mm. You can also buy this style of tip in 1, 1.5, 2, and 2.5mm (The latter is in a "short" version, CSF25. (I have them all, and the smaller ones are great for point to point jumper wires and such).Another favorite of mine is the T18 K, knife tip. The claim to fame is that it holds a lot of solder and is sort of chisel-shaped, but it is angled so you don't have to position the board exactly just so to use it (twisting the iron changes the angle, unlike a chisel where the edge is always perpendicular when the blade is flat on the board), and it has a sharp point that can be used to pin components down while adjusting them with tweezers. Also, unlike a chisel, it is tinned on the working edge, only. Regular chisels have a tinnable surface extending up the shaft which is maybe useful for thru hole stuff. But just an extra hassle for SMD, IMO.These are my most used tips, period. To round things out, I also sometimes use a regular bevel. T18-C2 and T18-C3 are the most useful, IMO.It has literally been over a year since I used a conical tip for anything. Maybe 3 years since I tried a chisel. I do a lot of SMD soldering.But don't forget the secret sauce. If you are going to solder any SMD, you will be wanting some liquid flux. MG Chemicals MG835 works fine to me. You can buy it in 125mL bottle or 1L bottles. Cheap as dirt. 100 packs of syringes and plastic tips are also cheap as dirt.A knockoff tip assortment is fine to start. But there are several useful styles that won't come in this assortment. And once you find what you like, you owe it to yourself to buy genuine Hakko. They work better, and genuine T18 tips seemingly last forever.QuoteTo each their own. I get the most mileage from the huger tips. CSF25, CF3, K. If you do a lot of bodge wire rework or protoboard stuff, maybe you will get more use out of the finer tips. Even here, I prefer the CF1/CF15/CF2 over the pointy conicals. Tinned-face-only tips and liquid flux make quick work of anything, really.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 28, 2018, 04:36:26 am
content: Get a decent hot air machine. Don't get hung up on the all-in-ones. Hot air makes SMD sooooooo much easier.https://www.amazon.com/Aoyue-852A-Digital-Rework-Station/dp/B000HDDXY0That's what I bought, but if I did it over again, I wouldn't get the pickup tool. There is only one pump in the device and picking up chips cuts off air to the air gun.The steel ball gauge is okay. It does give you an idea that the air is flowing, but I find that its fairly useless for judging actual air flow.I don't have a preheater yet, but if you have a big ground plane, it's probably nice.I've been able to solder down chips like this now:https://www.digikey.com/product-detail/en/semtech-corporation/TS30041-M033QFNR/TS30041-M033QFNRCT-ND/6605531It takes a little time to learn.A flux pen is recommended. For real small stuff, tin the pads. Wipe over it with the pen. Heat it with the air gun. Watch it real closely. It will move -- at least you will say to yourself "did it move" -- then perhaps give it a light tap on the top. Be careful with the tap and hit it square or you will knock the chip out of place. If you tap it and moves back to where it's "supposed" to be, you probably got the chip down and all of the pins soldered.Get a loupe and one of those USB microscopes for inspection.Also, don't get a "lifetime" supply of paste. It does go bad. Mine is a year old, and I think it is bad. I've not even used half of it and I have done a handful of boards. The flux isn't as active as it used to be.As far as soldering iron tips, I like the cylinder type with a bit of an angle on the end. I go with the biggest one I can fit into the space I'm working. Bigger tips transfer heat better and make it easier to cleanup bridges. A "brass scrubber" helps a lot when cleaning the tip. When you need to clean up bridges using a big tip with the scrubber lets you get the extra solder off fairly fast. Lots of flux helps too, so don't only rely on a flux pen.

author: KL27x
author_rank: Super Contributor
timestamp: February 28, 2018, 05:39:52 am
content: QuoteThis is typically called a bevel or hoof.Quote+1Quote858D is very popular for good reason. It's like $30.00 in the US. My $200.00 station went through 1 heater replacement after 2 years. And I never used the iron or pickup tool on it. My 858D is going strong with no issues, and it has seen much more use over its lifetime.

author: paulca
author_rank: Super Contributor
timestamp: February 28, 2018, 01:22:15 pm
content: I started doing this recently. It's a lot easier than expected.To hand solder passives I tin a pad, then melt the pad and stick the component on it with tweezers. Then solder the other side. Flux helps stop "nipples" from forming or helps remove them when they do form as the solder tries to follow the iron when you release.ICs. "tack" one corner, as with the passive, then I flood them with flux from a flux pen and take some solder on the tip and draw it over the pins slowly, watching that the solder flows out behind the tip. It is MUCH easier to fix too little solder than too much!I also tried a hot air 858D and it makes things a lot faster and easier. It does require solder paste and a suitable applicator needle though.Get your self some practice boards. I recommend one of these:https://www.ebay.co.uk/itm/SMD-Components-Solder-Practice-Plate-for-Training-DIY-Module-Electronic-Kit/141890124297?_trkparms=aid%3D777003%26algo%3DDISCL.MBE%26ao%3D2%26asc%3D43782%26meid%3Dcbd59ae4472140cf81f7e1a00ae0ced2%26pid%3D100012%26rk%3D1%26rkt%3D11%26sd%3D273043902602%26itm%3D141890124297&_trksid=p2047675.c100012.m1985They have a good range of parts/packages.EDIT: Also don't try and be a hero with your eyesight. Buy a Jewelers visor.

author: rstofer
author_rank: Super Contributor
timestamp: February 28, 2018, 10:56:55 pm
content: You can also do nice work using solder paste. I just bought a syringe of lead/tin paste:https://www.amazon.com/gp/product/B017RSZFQQUse the small pink tip to dab solder on pads for resistors and capacitors. Run a string of paste perpendicular to the pads for SMD ICs.Place the parts, hold them in place with curved tweezers and hit the joint with the soldering iron tip.Alternately, Google for 'drag soldering'. I use flux paste like this:https://www.amazon.com/gp/product/B00425FUW2There's no voodoo in SMDs until you want to take them off. I have an air gun for that but I usually just cut the pins, remove the package and then individually remove the pins. My biggest concern is lifting pads.I just did some reflow soldering on 0805 and SOIC this morning. I applied paste solder as described above, placed the parts and stuffed the board in a converted Black and Decker InfraWave Toaster Oven. A few minutes later the board was completely soldered. There was one solder bridge that I fixed with SolderWick.SMDs really are my preferred method. They take less space, they don't clutter both sides of the board and reflow soldering is FAST.A hotplate like this:https://www.target.com/p/elite-cuisine-electric-burner-hot-plate/-/A-51107299?preselect=49124277#lnk=sametabThese can do a nice job as long as the plate doesn't have a recessed area where the board won't get heated properly. What's properly? Put the board on the plate, turn the temperature all the way up and watch the board. When all of the solder has reflowed, remove the board with tweezers. Then turn off the hotplate.It's pretty clear the hotplate method doesn't comply with any recommended temperature versus time curves. But it works well.

author: paulca
author_rank: Super Contributor
timestamp: March 01, 2018, 10:22:48 pm
content: Just thought I'd share this...I build one of those SMD DIY LED chaser kits tonight. Used the hot air to do the whole board at the same time. Learnt a few things.* 260*C is too low, 300*C works better.* Amtech cutting mats don't like 300*C air, they begin to smell horribly and go shiny, I'm sure not long after that they will start to blister and melt, possibly though unlikely ignite. This is only of real concern around the edge of boards as the thing under your work will get the direct 300*C air. (What do you guys use?)* When you lay the paste out for ICs put it towards the outer end of the pads, if it's too close to the centre you can end up forming a bridge UNDER the chip.That last one took me an hour to fix. I tried all manor of flux, soldering iron, hot air to get the bridge out, but... the chip was sitting on top of it. Ended up hot airing it to remove the chip and remove the solder bridge with desolder wick, then hand soldering the chip back on.

author: tautech
author_rank: Super Contributor
timestamp: March 01, 2018, 11:15:36 pm
content: Quote from: paulca on March 01, 2018, 10:22:48 pmJust float a good amount of liquid flux in there, apply heat and the bridgeshouldsplit unless there's too much solder in there anyway.I prefer the rosin fluxes for this as they don't flash off like some liquid ones do.Practice makes perfect.