SMD Soldering Feedback - Page 1
Forum section: electronics / beginners

author: gsgx
author_rank: Contributor
timestamp: June 11, 2023, 06:19:51 am
content: Hi, I'm relatively new to soldering and very new to SMD soldering. I've been practicing soldering some SMD components, and I wanted some feedback on how to improve. Specifically, I need some confirmation I understand which joints aren't great and what to do about it. My process is to get some solder on one pad, place the component, melt the solder to get the component to stick, and then solder the other side. You can find some photos below. I'm using lead-free solder.Some specific questions:- I think the right joint of C1 is how I want the rest to look, can anyone confirm?- I feel like too many of them are "blobby" (left side of C2 is particularly bad), is this because I'm using too much solder?- Do any of them look like there's not enough solder? Maybe the right side of C9 and C10? I know it may be hard to tell from a top-down photo.- Some of the joints are "pointy", like the right side of C4 and C5. It happens when I take the iron off of the pad and some of the solder gets pulled away from the pad. I'd guess this means I need more flux, or could it be something else?EDIT: Could someone point out what I'm doing wrong with the inline image attachments?

author: Siwastaja
author_rank: Super Contributor
timestamp: June 11, 2023, 07:34:05 am
content: Yes, the right pad of C1 is pretty much spot-on.The reason why blobbiness is bad is it hides whether the solder flowed into the PCB pad or not. It could be just a blob hanging on the component lead; or it could be actually connected to the PCB, you can't say by looking at it. Otherwise than that, excess solder does not matter. If you feel confident that you saw solder actually flowing and melting on the PCB pad and only applied too much after this, there is no need to rework IMHO.And that's usually the biggest challenge, get the solder stick on the PCB, especially if the PCB has large polygon pours or multi-layer ground fills. In such cases, pre-heating the board to say 120-140degC (which does not hurt the PCB and other components even if held for a long time) helps tremendously, as does applying flux to the pads using a flux pen right before soldering.Finally, hand-soldering is not a beauty contest. It's hobby/prototyping and most important is to recognize which problems truly reduce reliability. For example, R1 looks a bit ugly but it's 100% fine really. But C2 and C3 left pad leave a hanging question, are they connected to the PCB? Probably yes but can't be sure.

author: tautech
author_rank: Super Contributor
timestamp: June 11, 2023, 07:44:26 am
content: IMO all but the LH side of C11 have an unnecessary amount of solder on them.You need set up a tip cleaner of brass or steel wool and use it to remove excess tip solder and by retouching joints remove excess to get a better shaped solder fillet that should never be higher than the component.And BTW, welcome to the forum.

author: xavier60
author_rank: Super Contributor
timestamp: June 11, 2023, 08:06:50 am
content: I solder those sorts of SMD components using the same method. I use 0.6mm Sn63/Pb37 rosin core solders with a Hakko T18-S4 tip set to 350°C. The spikes and other unevenness is caused by low tip temperature and by not using extra flux. Generally, the flux contained in solders is only active while the solder wire is first being melted. When the blob is remelted, the flux fails to keep the solder from oxidizing, preventing the molten solder from forming a smooth fillet.It's difficult to control the amount of applied solder if it's too thick.I use CAIG Rosin Soldering Flux RSF-R80.

author: agehall
author_rank: Frequent Contributor
timestamp: June 11, 2023, 08:49:36 am
content: Not too bad. C1 is, as said, pretty much spot on. Let me guess though - you didn’t use flux? It will help a lot if you apply good flux to the board before soldering.To up your game even more, use hot air to allow surface tension to straighten out components after initial soldering.That said, I would bet all of the joints are good. Too much solder and not 100% straight components when hand soldering isn’t a big deal ime.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: June 11, 2023, 10:01:19 am
content: For hand soldering that's a very good effort, especially with pesky hotter melting lead free solderIf you don't already have a solder flux pen, get one. Flux is good. Plus, obtain some IPA (isopropyl alcohol) to clean away the surplus flux afterwards.Don't over work SMTs. If it looks wrong, remove the part and start again.Plus, if you're designing your own PCBs, choose SMD pads described "for hand soldering", as the copper area is helpfully larger.Keep on with the steady hand

author: xrunner
author_rank: Super Contributor
timestamp: June 11, 2023, 10:56:13 am
content: Not bad overall. When you see something like the right hand side of C3 and C4 going on, you can put a little flux on and touch it up.

author: mariush
author_rank: Super Contributor
timestamp: June 11, 2023, 11:43:54 am
content: The ceramic capacitors are too small for the footprint.Indeed, you're using a bit too much solder, probably you're using a thick gauge solder wire, try going down to 0.5mm-ish or 0.38mm solder wire, it may help a lot. T18-S4 is conical, which is somewhat of a negative, other shapes are better for surface mount components. Maybe T18-D12 would work better:https://hakkousa.com/products/soldering/soldering-tips/t18-d12-chisel-tip.htmlMaybe this series would help

author: xavier60
author_rank: Super Contributor
timestamp: June 11, 2023, 11:58:16 am
content: Why is the T18-S4 being conical a negative? It's a very versatile tip, suitable for small SMD and much larger joints.More here:https://www.eevblog.com/forum/reviews/hakko-fx-888d-and-t18-bl-tip/msg3462698/#msg3462698

author: janoc
author_rank: Super Contributor
timestamp: June 11, 2023, 03:18:11 pm
content: Quote from: xavier60 on June 11, 2023, 11:58:16 amConical tips in general are difficult to work with because you don't get sufficient transfer of heat to the joint. To even get the solder to melt you have to apply the tip sideways to the joint - and that may not be easily doable on a crowded board (incidentally that's also why various "bent" tips exist).You will get a lot better results with a chisel ("screwdriver") style tip. Don't fall into the trap of thinking that for SMD you need extremely fine and pointy tips, that's completely false.

author: xavier60
author_rank: Super Contributor
timestamp: June 11, 2023, 03:31:55 pm
content: Quote from: janoc on June 11, 2023, 03:18:11 pmHave you tried a T18-S4 tip? I have been using them for years and there is no problem with thermal transfer to any type of joint even though it does need to make side contact.

author: tooki
author_rank: Super Contributor
timestamp: June 11, 2023, 03:40:45 pm
content: Quote from: tautech on June 11, 2023, 07:44:26 amAgreed. It should be concave.With that said, it also depends on pad geometry and component size. It’s really hard to hand-solder an 0402 with small pads and still maintain a convex fillet.So in practice, as long as it’s not a bulging blob, don’t worry about it too much.As for the solder spikes: use more flux, but also, if you ever see them happening, re-tin your tip. Two things cause the spikes: oxidation and solder “contamination” from copper, gold, etc from pads and component leads dissolving into the solder, which happens more if you take too long (which is normal when starting out!). The oxidation and/or unwanted dissolved metals change the properties for the worse. When you observe this, “rinse” your tip with fresh solder so that it drips off, wipe clean, rinse again, wipe again, and then re-tin with a small amount of solder to protect the tip and to act as a thermal bridge.Also, another comment correctly said that too low a tip temperature can cause spikes, and that’s absolutely true. But what’s also true is that too high a temperature can cause them, because higher temperatures promote both faster oxidation and the aforementioned contamination. So you want a temperate that is as low as possible, but as high as needed. It’s all about finding that middle ground, which is something you do constantly since it depends on the tip in use as well as the solder joint itself.

author: tooki
author_rank: Super Contributor
timestamp: June 11, 2023, 03:43:59 pm
content: Quote from: xavier60 on June 11, 2023, 11:58:16 amI don’t understand why people torture themselves with conical tips. I don’t find them to be superior for anything, other than maybe melting round holes into plastic or hot-pressing-in brass threaded inserts…

author: xavier60
author_rank: Super Contributor
timestamp: June 11, 2023, 03:46:20 pm
content: It's not your typical long pointy useless tip.https://core-electronics.com.au/hakko-t18-s4-soldering-tip.html?gclid=CjwKCAjw4ZWkBhA4EiwAVJXwqc885qEimp3MvvJ700BukX6wlhbQqUvdjvzeqYm_NU0artWf1RmbARoCBEYQAvD_BwE

author: tooki
author_rank: Super Contributor
timestamp: June 11, 2023, 03:56:10 pm
content: Quote from: xavier60 on June 11, 2023, 03:46:20 pmI know it’s not a long pencil tip, but a stubbier conical. But I still don’t see why one wouldwantthat shape when better ones are available.

author: Jwillis
author_rank: Super Contributor
timestamp: June 11, 2023, 05:38:54 pm
content: Your practice soldering doesn't look to bad . Don't be afraid to use extra flux. Spiking ,pitting and dulling can all be attributed to oxidation. Everyone will have their own preferences on brand but I find a liquid or gel for SMD and a basic rosin paste for through hole work just fine.Chisel tips for SMD work the best for me. A 1.8mm, 2.4mm or 3.2mm chisel depending on package size.If your still getting a lot of solder blobbing try reducing the size of your solder wire. Usually a .8mm diameter is plenty for package sizes of 1225 down to 0805. Reducing the solder size down to .4mm for package sizes less than 0805 helps me.If you find that your trouble keeping the component in place a SMD adhesive might help. It also helps to keep the component from lifting on one side because of the contraction of cooling solder on the other side.

author: gsgx
author_rank: Contributor
timestamp: June 11, 2023, 07:32:09 pm
content: Thanks everyone for the advice and the supportI've been using a chisel tip, I tried a conical but it was definitely more difficult. I should also mention I'm using a $20 soldering iron I bought around 7 years ago, so I definitely don't trust the accuracy of its temperature and I don't have a thermocouple to check it. It also doesn't have the feature where when you set it down it automatically cools down, so I can also see that leading to some problems with oxidation if I didn't thoroughly clean the tip between placing a component and soldering it (don't worry, a "proper" soldering station will be my next purchase).Regarding using hot air, I had purchased an Atten ST-862D but I'm still waiting to receive it. I'm hoping I get it next week to test it out.Quote from: Siwastaja on June 11, 2023, 07:34:05 amThanks, I wasn't sure about the blobby joints, but this helps me understand what the problem with them might be. And this definitely makes me feel less self-conscious about how it looksQuote from: tautech on June 11, 2023, 07:44:26 amI've been using brass wool for cleaning, but will be more mindful of this going forward. Also I wasn't sure if the solder should just cover the top edge of the component or be below it, will try to keep it below the top edge in the future and to keep it concave. And thanks for the welcomeOne question about this comment:Quote from: tooki on June 11, 2023, 03:40:45 pmThe solder contamination could definitely be a factor, I'm still getting a feel for how long to hold the iron to the pad. Other than cleaning and re-tinning the tip, if I suspect this contamination should I attempt to remove the solder with some solder wick first or should I not worry about that?Overall, I think the main things for me to focus on are keeping the tip clean and free of oxidation and adding enough flux. I've tried a flux pen in the past (SRA #99-20 RMA Rosin Flux Pen), and while I found it much more convenient than tacky flux, I found that the tacky flux produced better results for me (MG Chemicals 8341 No Clean Flux Paste). But I'll try both again with some different brands.Thanks again everyone!

author: mariush
author_rank: Super Contributor
timestamp: June 11, 2023, 07:32:59 pm
content: Quote from: xavier60 on June 11, 2023, 11:58:16 amI said somewhat, because it's not the worst choice, but there are better choices. It's about thermal mass, how much of surface is in contact with the component and the pad and other factors, like how well can it be used for drag soldering or for soldering a QFN package (lots of leads close together, a chisel tip could be used to solder the leads easily while the conical would be harder to use)Some tips about choosing the right tip:

author: xavier60
author_rank: Super Contributor
timestamp: June 11, 2023, 08:18:00 pm
content: This is an example of what the T18-S4 tip is capable of.The brass screws are M5x25. The the PCB is 2oz copper. The tip has good heat transfer. I have since started using a large chisel tip.So the T18-S4 has no trouble at all with small SMD components.This member also understands the useful attributes of the T18-S4.https://www.eevblog.com/forum/reviews/hakko-fx-888d-and-t18-bl-tip/msg3462698/#msg3462698

author: janoc
author_rank: Super Contributor
timestamp: June 11, 2023, 08:45:50 pm
content: Quote from: tooki on June 11, 2023, 03:43:59 pmOh you don't want to use conical tips for inserts! The insert will get stuck on the tip and you are screwed, likely destroying your work trying to remove it. For inserts there are special cylindrical tips.

author: tautech
author_rank: Super Contributor
timestamp: June 11, 2023, 08:45:56 pm
content: Quote from: gsgx on June 11, 2023, 07:32:09 pmYou're on the right track.Quote from: tautech on June 11, 2023, 07:44:26 amQuote from: gsgx on June 11, 2023, 07:32:09 pmExamine commercially built PCB's for guidance.I too use chisel tips but only down to 0603 where I'm not interested in any going finer.The corner contact of a 2.4mm tip gets the job done just fine with sufficient thermal mass to also take on larger components.About my tip cleaning comments, a small tub with tip cleaner brass/stainless wool and a plunge or 2 into it will strip the tip of all solder and retouching previously made joints will pull a little solder from them so to get a better fillet.A friend gave me a small ceramic cup for tip cleaner wool that has sufficient mass to stay where its put when cleaning tips.Otherwise a small tin weighted down with molten lead can serve the same purpose.A few small tweaks make for a more enjoyable soldering experience....have fun as it should never be a chore.

author: Old Printer
author_rank: Frequent Contributor
timestamp: June 12, 2023, 03:17:19 pm
content: Curious if you for-see a need to use lead free solder? Many hobbyists opt for the old standard 60/40 which is easier for a beginner to master. Good lighting and possibly magnification are also a couple of important ingredients that are easy to overlook. Check out some YouTube vids by Louis Rossmann, he is a bit of a guru in reworking SMD and a big liquid flux proponent.

author: gsgx
author_rank: Contributor
timestamp: June 12, 2023, 04:30:11 pm
content: Quote from: Old Printer on June 12, 2023, 03:17:19 pmI'm mainly using lead-free solder because I have cats and I'm worried of them getting lead poisoning. I make sure to thoroughly clean my soldering space, put away anything that would have solder on it, and only allow them in that area supervised, but I don't want a mistake on my part to end up being lethal. Of course, even digesting lead-free solder is bad for them, but it's not as lethal as lead solder.And yea, Louis's videos have been very helpful

author: Old Printer
author_rank: Frequent Contributor
timestamp: June 12, 2023, 06:14:14 pm
content: Gotcha on the cat thing, got a puppy myself that needs to be considered and honestly did not think about her getting into solder, but she eats everything so I should.

author: EPAIII
author_rank: Super Contributor
timestamp: June 13, 2023, 09:29:49 am
content: While there certainly are dangers associated with lead, I have to say that the need for lead free solder in hobby electronics is certainly minimal. We don't need tons of lead on millions of commercial circuit boards leaching into our water table from land fills. But the use of lead based solder on the few boards that hobbyists make is not going to cause any damage to either them or the environment. I have worked with electronics and used lead based solder for over 65 years, often on a daily basis and am still quite OK.As for cats, I can't say. Would they lick and lick and lick any droppings? I don't know. I once saw a duck that drank from an open container of anti freeze that was left unguarded. He only got about three feet from it. So animals can be caught by dangers that humans would never fall for. But it is still difficult to see how they could get enough lead from any single encounter. They can't get much with a lick and any pieces they swallow would pass through with 99.9% of the original lead remaining in the piece. The children who got lead poisoning did not eat just one paint chip.

author: Rettox
author_rank: Newbie
timestamp: June 14, 2023, 02:28:06 am
content: You may obtain better results using solder paste and a heat gun. Apply a VERY small amount of paste to each pad and place the component (I tend to use Lead based paste as it gives a better finish and is easier to work with)Use a heat gun on the lowest air speed and warm the board to about 160 degrees. You can then quickly heat at about 280 degrees at which point the solder will flow (I use an IR oven for large batches but a heat gun is cheaper for rework and day to day projects)I use solder wick with some RMA flux to remove any excess solder or bridges.A binocular microscope is a useful aid for final inspection.. As with all techniques practice, practice practice

author: armandine2
author_rank: Frequent Contributor
timestamp: June 15, 2023, 12:15:21 pm
content: I too have just started with SMD soldering - last night I used a different tweezer as I found it was mostly my first solder joint that was not making a good concave fillet. It seemed to help keep the device down onto the pad, as the solder was reflowed.

author: janoc
author_rank: Super Contributor
timestamp: June 15, 2023, 05:46:43 pm
content: Concerning tips for metal inserts, you want these kinds of tips:https://cnckitchen.store/products/einschmelzhilfen-soldering-tips-m2-m2-5-m3-m4-m5-m6-1-4-m8-100-lead-and-cadmium-freeThey fit on many common cheap irons, I have bought a cheapie for 20€ just for these.Conical tip will wedge itself inside the insert because of its shape, plus it gets wider as it gets hot - and the insert is stuck to the tip.