Easy way to Solder Surface Mount Parts! - How I do it
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- Опубликовано: 21 авг 2024
- Was working on some boards today and I thought maybe others might find this kind of video useful. Note that this is just the way I deal with surface mount soldering... people that do this sort of thing all the time have developed it into an art of sorts. But whenever I need to assemble up a couple prototypes before sending out for manufacturing, this is my go-to method.
Sorry about the audio on this one... just used the camera's built in microphone.
By the way, these boards are going out to the patrons of this channel this month. Thanks again to everyone who supports what I'm doing here: / kdarrah
And that board I was working on: www.kevindarrah...
So, here's the list of things shown in the video:
I buy the stainless stencils here: www.electrodrag...
Plastic Stencils here: www.pololu.com...
Hot Air Station here: www.amazon.com...
Solder Paste: SMD291SNL10 (I keep mine refrigerated when not in use, then sit out for an hour or so before I need it)
www.digikey.co...
Check out my Tindie store (trigBoard is available) www.tindie.com...
Thanks to all the Patrons for dropping a few bucks in the tip jar to help make these videos happen!
/ kdarrah
Twitter: / kdcircuits
For inquiries or design services:
www.kdcircuits...
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When doing solder touchup, adding a little solder flux to the joint first will work wonders for reflowing the solder and avoid possible cold solder joints. It probably would have fixed the bridging too during the touchup.
I don't know if someone has already written this down but I'm going to share it anyway.
If you want to use the solder paste syringe to manually dispense, then for the very fine pitch pads you could buy from your local pharmacy (if they are available) empty fine-tipped syringes (the insuline injection type) and use them as a kind of scoop.
You dump some quantity (paste) somewhere off the board and you use the fine-tipped syringe to pick up a small amount of solder paste each time to lay on each pad.
The reason I am suggesting a fine-tipped syringe and not a needle for example, is because the tip of the syringe is an diagonally cut tube which means it is concavely shaped ( kinda like a spoon) on the one side which can hold some paste more effectively than just something cone shaped.
It is a bit time consuming but it is a lot better than bridges due to excess solder and you can save yourself some trouble from having to use the hot iron and the wick. Sometimes using the wick removes more solder than it should, you cannot exactly control it.
The manual dispensing way presented in this video is fine if you want to go for it. I just wanted to share some of my experience, so no trolling please.
PS: Also Kevin Darrah, you might wanna start considering some hot plates for properly heating up and re-flowing for your assemblies (provided the boards assembled are one-sided and small enough to fit on the surface of the plate). Some components (and yes that includes ceramic caps and resistors) DO NOT like thermal shock as you probably know. A hot plate can be a cheap (kinda) solution to that.
Alright that's it, I'm out. Bye!
Kevin, thanks for the video. This is the first time I have seen surface mounting done and between watching the video and reading the comments I have learned a lot. It has made me feel that "Yeah, I can learn to do that".
THE best video I've seen - explains all steps, adds lots of tips, just excellent. It takes some of the "fear" away from surface mount.
Personally, I might have slipped some heat-shrink tubing over the too-coarse needle, and shrink it to have a finer applicator, but the fact he did it as is and it worked, is wonderful.
...and per a later comment, the heat-shrink could be cut at an angle to dispense somewhat downward, I think. Finding thin enough heat-shrink might be a problem. All this is theoretical.
When doing it without a stencil, just dab the solder paste to the components, Use a toothpick to wipe off any excess if need be, then place the parts on the board with your tweezers
Thanks for sharing. Just to add some point of benefit, when you paste the PCB by hand and you make a mess by bridging the pads, I would not recommend to use the iron for cleaning it as you did it here, rather run some flux over those pads, change the tip of the iron into a flat blade that covers all the pads of one side of the chip (they come in different sizes) then simply wipe them all outwardly, away form the chip, you'll notice the pads nicely and evenly soldered with no bridging at all. And finally, don't forget the golden rule, ESD protection. Carry on the good work.
You have everything ok. A friendly voice, and a very professional way of working. Everything you teach comes fine!
Take a small blob of blu-tak, shape it into a point, and stick it to the end of a pencil or empty pen. Makes a very accurate pick and place tool! The only thing it doesn't have is a release, so that's where your tweezers come in: touch tweezers to top of part, withdraw pick tool. The sharpness of the point on the blu-tak can be adapted for different part sizes, e.g. blunt for larger parts like your MCU, very sharp for teeny SMD caps and resistors. When blu-tak gets dirty and stops picking up parts, squish and remold - it'll be good as new.
I usually center the component, then add solder paste. When I was taught, I was told that they are very small solder balls inside the paste. So with that under the flat surface of your component, it allows the potential of that component moving around. It makes sense to me, and its the only way I've done it. Also, you don't really need to add the solder paste directly on the pads, just get it close. When the solder reaches melting temp it'll walk right up your pad/ lead. Downside is if your hot air jet tweaks when you're running it back and forth, you create a big potential for solder bridges. So steady hands are always nice lol. However, I suppose at the end of the day multi leaded devices are just generally synonymous with solder bridges. But you know what they say, different strokes for different folks. Just a different outlook on other methods. Great video man, thanks for making it!
Great video but I have to correct you on something. The capillary action only happens between the flat bottom of the pins and the flat pad because it's a narrow space and capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.
What you mentioned about the solder separating and grouping around the pins is due to surface tension not capillary action. Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible so droplets separate and group around the pins cleaning up the spaces between pins of solder.
thanks for jumping in with that!
Great comment, but I have to correct you on something. "Capillary" applies to narrow tubes. Surface tension is a more general term, and capillary action relies entirely on surface tension.
Liquids forming into droplets is another phenomenon that also relies on surface tension, in the case where a liquid adheres to itself more readily that to any adjacent surface or material, or in a vacuum.
Also "ability of a liquid" implies that the nature of the liquid is all that matters. The nature of the surface is just as important, as evidenced by the failure of solder to take on some surfaces. The solder will adhere if energy state of the surface in contact with the solder is lower than that of the surface in contact with the air. Systems tend to change to lower energy states when possible, sometimes needing a "push" in this case the application of heat in the presence of flux.
I think it is the combination of the two phenomena that make things easier while soldering
When soldering you do not want the liquid solder balling up. That phenomenon makes soldering more difficult, not easier.
Wow, Kevin you are indeed good at this. As an old school engineer I remember when we first rolled out SMD designs in the 80's thinking, well this is the end of the garage tinkerer. Obviously I was wrong. What impresses me most is the number of connections being made and the fact that you were able to make good ones without shorts/opens the first time. Keep it up. Maybe an old school guy like me will be motivated to give it a try despite the fact that my garage is full of old PIH stuff. :)
Watching this... one tip is you don't really want to crank up the air temperature that high. I assume you are using leaded solder paste.
You want as much airflow as is practical and as little temperature as is needed to do proper reflow.
With high temperature air and low air flow you are creating large temperature gradients and this is also damaging to components. You can have the top of your component be very hot (directly to very hot 400C air) but the pads still relatively cool. High air flow tends to equalize and spread temperature much better which means you can use cooler air flow.
Also try to soak the board and components in hot air in lower temperature before you get to actual reflow temperature. This is what would usually happen in professional reflow oven btw. If you preheat the board the gradients will be less and the whole process will be more forgiving.
The way I would determine is I would crank up the cool air until parts start flying away, then reduce it a bit. I would then crank up temperature to see when it takes few seconds to start reflow, not too fast, not too slow. I would soak the board from bit further away and when I'm satisfied I would close in with the gun and do the reflow itself.
It is not leaded solder paste. Would the temps be higher in this case?
@@BrowFinGarf that is right, as non leaded solder has a higher melting temperature
Great video! I don't know if anyone else mentioned this, but in addition to the capillary action, it's the surface tension of the molten solder that pulls the parts into alignment with the pads.
That's nifty. Very cool when the paste reaches that critical temp and reflows like that, very cool, haha. Can watch that for hours I think.
Great video! I've watched many SMD tutorials. It's helpful to see multiple engineers show their methods. Keep producing great content!
Something I have used to fix solder bridging is an iron tip with a flat face. Cleaned well, it allows you to drag the corner of the tip against the board, the face against the tip of the pins. The face of the tip wicks up the excess solder and by dragging the iron across the pins it evens out the solder left behind.
Can't remember where I picked the technique up from, but it works in a pinch.
armorer1984 link a video! Please!!
Congrats on the patience. :) I've done some small raster soldering by hand in the past and I find it too time consuming. IMO stencil is surely a way to go if you have more than 2-3 boards to do. Cheers!
When you are cleaning up the bridges it helps to apply some flux.
It took me too long to realise this, flux and a reheat does wonders :)
If you're applying it by hand it's easier to do it CNLohr style - using a toothpick instead of the syringe it came in.
oh man, that's a good tip! Most of the time I just pick up the stencil when I order boards, so hardly ever do it that way... probably shows in the video :)
The glass PCBs CNLohr makes are really amazing, too.
And he doesn't even have through-hole or breadboards, he just goes straight for the SMD, his prototypes are done like a final product lol.
Good show. It's good to see the two ways of doing it side by side and how cleanly they can be done. Thanks!
Good job. I never seen anyone use a stencil, but one thing I noticed when you didn't use the stencil was the crystal oscillator shifting position. from my experience, the solder paste has two states. it helps to firmly press down on the component until it reaches the chalky state. shortly thereafter, you can see the little spheres forming and identify the desired state.
Very COoL. Best video on SMT "start to finish"... Being a old-school 1w "resister scale dude" I never realized how do'able this was. You've INspired me to downSIZE. BTW.. Really nice (camera) work. Thank you (subscribed, of course:)
try tacking 2 corners of a quad pack. then run a bead of solder paste across the remain legs then heat. It should minimize the solder bridges as well as make it easier to set them in place. Add additional flux when touching up will eliminate the need for the additional heat source, also try using the drag method that's how I was taught.
Thanks! Very helpful. Especially useful that you showed best case scenario with template mask and worst case sloppy hobby scenario with hand applied solder paste. Both worked! Great that you showed how to clean up a sloppy job including solder bridges. Good job! Nice video!
Even you drank too much coffee, your hand is still more steady than 90% soldering youtubers LOL
Ha Ha. almost 70 but don't have the shake yet. Hopefully it stays away.
Hey man ! thank yu for the video ... I have been soldering the pins one at a time ... killing my eye sight ... will definitely change to paste method now ... darn .. got all the tools to do it ... could have saved hours of work .... I must have built up more than three four thousand boards bu hand .. thanks again
One of the best explained tutorial that i saw about soldering SMD. Thaks from Argentina.
there are many videos showing this.. but this one is the best
could just drag solder the chip. and hit the caps and resistor just as quickly.
and look just as good
Good video Kevin but as someone else pointed out it's not the capillary action, it's the soldermask that prevents the solder from attaching itself to anything other than the pads. Well in theory :)
This is a great way to do if you don't have shaky hands. Well I DO!PCBWAY will make ten 100x100mm boards for only $5! Get the red ones they look and work fantastic!
Nice, but in the second method could you not have put the paste on the pins and then put the chip on the board as a way to keep from using too much paste?
Your vids are some of the easiest & informative to watch. Thanks on the stencil tricks!
Good video. I like that you've demonstrated both methods and how to fix bridges. Also, thank you for providing the links to the tools and parts (reflow station and the PCB service provider).
no prob, glad you found this useful
This is exactly the kind of project that I was looking to do for one of my future projects. This stuff is awesome!
The more examples of technique the better. Everyone has a style.
I went to Kennedy Jr. High in Woburm,Ma. I remember a tall thin classmate with your name. Fantastic video,and technique.
When applying solder paste without the use of a stencil, simply paint the paste on with a small paintbrush. A small amount of paste goes a long way and a thin coating will generally not result in bridging.
Now after your tut I have the confidence to try my hand at this technique.
It is the best practice for large pcb quantities.I think that the pcb manufacturer can make the solder mask stencil also and ship it along with the boards to make the life easier somehow.Otherwise you have to etch it on your own but it worths in massive production and not for few boards.
you could have used flux to get the solder bridges away
He did, the wick was soaked up with flux.
Yep, I've only done that way over, literally a million times in my life.
It does take a skill set, many people will never have ;-)
Either you've soddered decades doing nothing else or you literally don't know the definition of literally.
Who knows - maybe he works at Foxconn. :P
I've done it that way _physically_ a million times. Get on my level, nerd
Excellent video. Really cool and makes me feel more comfortable possibly making my own boards with smd components. What I have done before with soldering smd is use really fine braided wire as a wick. I have a large roll of telephone wire that actually used fine braided wire instead of solid. I almost threw it out but if I twist the braid really tight it makes a fine solder wick.
Use a hotplate and preheat the boards. Then while still on the hotplate use the hot air to flow the solder. Allow the solder to set before removing the pcb.
The most questionable but super cheap method is to put the PCB on the hotplate cold, let the heat rise until the solder flows then turn off the power and allow to cool. (Some components don't like this.)
Final cleanup with low water isopropyl alcohol (91% or better).
You should be a surgeon 😷 very steady hands - great job.
Kevin, I have stubbled on your youtube once again.. Awesome as always... great job showing how to do it.
Dip a toothpick in the gel type flux and use that to pick up the components. I find you have much more control than using tweezers. Once placed onto solder paste the component will release. Obviously a vacuum pickup with foot pedal is even better.
havent tried it yet but ive seen an etch done wit flattened pop can with coating removed.... toner transfer and acid peroxide etch. I might give it a shot at some point with riston. Last summer I construsted a vac press exposure box from plexi, low iron glass, 365nm 4.1w led from digi key, vaccum pump from ebay/china, pvc, and weather stripping. Also a vertical bubbler tank for cupric. all i lack at the moment is a tested/confirmed stencil making system. otherwise i can do 8mil on 2oz and enough alignment on dl to do through hole. I figured out that part is easy if i add marks to transparancies and align then glue a strip of preff board between them...makes a hinge that the cc goes between then exposure press box does rest, flip and repeat. I usually drill a hole through template sandwitch and cc so alignment is confirmed on flip. only shit part is i dont want cupric inside and mn has a limited etch season. otherwise a 4x6 dl costs like 4 bucks in consumables.
Or, if you're me, and really poor, i.e. I can't afford a hot air reflow station, you hold the board six inches over a BIC lighter and hope for the best. :P
I've actually soldered a QFN24 that way (a CP2104 USB to UART chip), and yes, it worked.
I just received two of the Atmega328 boards. I'm waiting on the SMD 328s to arrive and then into the Toast-R-Reflow. Good work Mr Darrah.
Thanks!
Can you check me on this. C1 10uF and C2 and C3 are 100nF?
Beautiful! Great video! I don't have a stencil (although after watching this I think I will pay the extra for one next time) but instead apply paste directly using the pointy end of a cocktail stick. Seems to work OK.
Thank you! Thank you! Thank you! I appreciate a human explaining what is going on!
400 Degree Celsius? That's very hot for that little bugs. Try something about 230-250. And the 858 normally contain smaller nozzles. So you don't need to wipe insanely over the board to be afraid of picking up some components accidently. Just move slowly and smooth from one pin to another.
Put a bit of solder in the wick first before using it. It transfers the heat through the wick much quicker. Use flux heavily during the wicking.
Cool. so satisfying to watch how the paste melts
the 2nd method needed the pins flooded with flux and a little less paste on the pads. then it would come out just as good !
Great demo. I especially loved the mask vs no mask.
Wow, I didn't think the none stenciol solder paste method would have turned out as nice as it did.
I've seen this done with a concave tip and flux - very fast and clean.
Great video! Really enjoyed seeing how this can be done at home.
Great video! I've watched it like a mini-thriller :D
P.S. I think that in some cases it's good to check for continuities with a multimeter before testing an assembly.
That was awesome. I learn something every day.
Apply flux to the shorted pins and then heat those pins with an outward motion and the solder will come right to the iron and off the end of the pins.
Excelent job Kevin! Congrats! Today I learn something very important from you. Tnx!
Well Presented and invaluable. Thank You, Kevin.
Great demo. Clearly explained. Thank you.
I can see that the stencil makes a much neater job! Can you make the video again with tighter angles, and a fixed focus, as the camera keeps going out of focus...
What a great demonstration, thank you very much.
Did you burn the bootloader using your USBasp? Or using another arduino?
Don't do it with a wick, just apply flux, heheat and it will auto flow to your iron, it also helps to have a hook tip for that.
Thank you SO much for this video! Super informative and helpful. I wish I could give it more than 1 like!
Why not apply some paste to the pins and feet of the components and set them in place or apply some regular solder to the pins and feet then apply some flux to the board using a solder gun or a halogen light (use the bulbs with a reflector behind the light).
Like a lot of other people I use an electric frypan.Works a treat.
I like to just drag solder with plain old leaded solder (60/40 works well for me) and ChipQuik flux paste.
Good informative and visual tutorial
Don't know if this helps - my paste dispenser has a smaller needle and needs a bit of pressure to get it to come out. I found if i held the dispenser quite vertical and gently tap I could control how much comes out to a high-degree. I literally apply paste to each pad one by one this way under the microscope. Then try and drop the components onto the pads so as not to smear the paste and then the heat-gun reflow completes neatly. I'm using lead free too - not sure this matters.
If you do not have a stencil an easier method to do this is what is referred to as the poor mans method. This entails pretinning all of the pads for the components on the PCB first using standard solder and no clean solder flux. Once the pads are tinned clean the PCB with isopropyl alcohol, apply no clean solder flux to the pads, place the parts then hot air reflow everything. This method allows you to more accurately apply the solder and reduce that bridging. If you do use a smaller nozzle on the hot air gun, the temperature can be reduced, 400C is in the danger zone as far as what smd components are designed to take. You should be able to reflow at around 315C or about 600F. Size of nozzle, air setting and distance from the PCB all will affect the temperature of what you are working on.
"The boards look like they were professionally made" - Well, they were, man, they were :)
oh thanks!
It's not capillary action; SMT pads do not form a capillary (tube). It is wetting balance that produced self-centering as the solder melts.
Some flux and drag soldering would be a lot quicker...
Maybe a suction pen for mounting the chip. ;-)
Damn if I knew solder paste worked like this I wouldve ditched regular solder years ago.... Does the 400 degrees not damage any of the components tho?
This was ultra helpful. Thank you.
soldering paste = magic!
Love this video. Very informative. Thanks for making it!
"Drank too much coffee" always an excuse
16:00 before touching to fix the solder bridges the chip pads need flux in order to make the solder stick to the pins ...
Thanks for sharing this with us!!
If you already have parts on one side, how do you do the other side?
When you do the bridge cleaning using excessive heat can those tiny electrical path damaged?
I do not see two surfaces there for which capillary action would happen
the phenomenon you want to refer to is called surface tension (due to surface tension liquid would always form surface which is smallest possible for amount of liquid and other surface on which it rests)
Two comments 1. a heavy size chrome plated needle can be used to clear hot solder bridges. Solder will not stick to chrome plate. Part needs to be in a jig. I have seen a pro do this sort of work on a Soic device using just high activity syringe dispensed solder and the solder just wicked off the pool of solder on his iron. However these days- late 2018 , that SMD mounting solder seems not easy to find in commerce. My tuppence. TEF.
you have some very good information that has helped me quit a bit, I'm curious what kind of education you have and are you an engineer for a company. I became interested in computer programming at a young age with a commadore 64 and over the years i have kind of played around with programming. i have a couple of years of electronics engineering, but i never attained a degree. Almost all the electronics knowledge i have is self learned and you appear to have quit a bit of knowledge, so i'm just curious if your knowledge is self taught.
Great video really helped me out
Have you tried using flux for touching up the manual one? I think it would make it much easier :)
thanks for the video
2 quick questions. I looked through the comments and didn't see these questions asked. sorry in advance if I missed them.
1 what thickness is the stencil?
2 what is your paste expansion rule? how much larger is your stencil opening than the pad you are applying paste to?
thanks in advance.
Ron Morgan hmm, I remember having to SHRINK the stencil holes for a 328p. Just fyi.
Just a thought, but wouldn't you have more control over where the paste goes (when not using a stencil) for the chip pins by applying the paste directly to the pins, and then positioning it on the board?
Super helpful man!
Could you add the paste to the micro first then set on board? That way gaps between legs might not get filled in
I wonder if 3D printers could be modified to print solder paste directly on the board.
no such thing as too much coffee lol
Agreed.
Would it be better to heat the PCB from the other side? I damaged a bunch of MOSFETs recently.