EEVblog #186 - Soldering Tutorial Part 3 - Surface Mount

hi welcome to the EEV blog and electronics engineering video blog of interest to anyone involved in electronics design I'm your host Dave Jones hi it's surface-mount soldering time part 3 in the hand soldering tutorial and today we're going to do surface mount technology we've looked it up the tools in the first part through-hole components in the second part and surface mount a lot of people think it's really hard but it's not it's an absolute piece of cake use the basic techniques you did last time few more little tricks and you can solder really first-class stuff with not much experience at all and some very basic tools let's take a look at it let's start out by looking at some basic surface mount components here up here is your standard quarter what through-hole resistor everyone's familiar with now this is a 1206 size surface mount resistor this is a 808 oh five surface mount ceramic capacitor this is an the same size Oh 8 over 5 surface mount resistor this is an O six a 3 surface me resistor and this is an O for o to surface mount resistor they do come even smaller than this tiny ones that are you see not really ultra miniature mobile phones and things like that now the 1206 but these are the basic standard sizes that you'll deal with in terms of in terms of your basic resistors and capacitors your basic passive components now the 1206 up here it's an absolute monster Stevie Wonder could solder this thing it is so damn easy let me tell you now o 805 s really very easy to do as as well once you get down to oh six oh three gets a little bit more touchy but I can easily do Oh 603 by I I don't need any magnification at all and you should yeah most people will generally be able to work sorter and OH 603 so if you're designing your boards especially for our hand soldering and even for surface mount solar in as well try and avoid the O 402s now I can those boy I just but I much prefer to use up to solder under four times four times six magnification they're just so that I can you know just so that I can keep a much tighter control of how much solder I feed on the the joint enter and just and inspect the joint at the same time as I'm doing the component so if you're designing your own boards I would stick to oh six oh three and up because the once you get down Oh 402 if you're actually getting on PCBs hand-assembled prototype they'll charge you a lot more for Oh 402 is because they will generally solder them under the microscope as well whereas if you're getting some prototype board hand soldered Oh 603 and up they can do by eye so really just put some thought into which components you use don't just jump right in and use oh four oh two is now for today's example I am just going to solder and oh six oh three part and if you're talking about our automated pick-and-place assembly of your boards when you're designing your boards put a bit of thought into it once again if you use AA 402s you might be in trouble because there are basically two classes or two technologies of surface mount pick-and-place machines cheaper and older designs can only do a six oh three and above components on to a two at least a reliable level they might be able to do Oh 402 but the yield isn't as good so if you're getting your board assembled by manufacturer they may actually charging more to use are to a place oh four oh two components because they might have to use one of their more advanced machines are the yield might not be as good and things like that so just put a bit of thought into it it might cost you a bit more to go down there so don't make it an arbitrary choice to go to before it is make sure you have a reason to do it now here's our oh six oh three resistor that we get a solder onto this board and as you can see it's going to be fairly easy because the pads are actually quite large in comparison to the component they do actually extend out further and this is great for hand soldering now if you don't know if you're laying out your own boards like this the IPC footprints the international standard footprints they actually come in three basic sizes what's called our normal least and most pad size now I'd recommend using the normal or the most pad size most means it's got the largest pad size and they're the ones that are suitable for getting your iron in in there to make contact with both the pad and the end the end cap on the component at the same time and that's important if you use are the least pad size or even a custom pad size some pads are really no bigger than the tiny little end cap on that resistor and really there's no way that you can actually get your iron in there to make contact with Bo if you could put solder on the end and bring it over and maybe get under there and actually thermal or even thermally transfer the heat through the cap onto the pad and it gets really nasty so just if you're actually designing your boards and you think that they may be reworked hand soldered or they're going to prototypes are going to be a assembled hand soldered if you can afford the room on your board if it's not a super compact layer highly recommend you go for a larger pad size so that you can get that thermal contact now we're going to use a contact we're going to use a method today called the art tack and reflow method for doing these components and it you as you'll see later it applies to other parts of work as well it basically basically means that we're going to tack the component down first and then solder the other side and if I'm doing a whole array of components like this I will do it in like a batch process and as as well I'll do a single resistor here but if I'm doing a whole bunch like this I would go through and apply solder to I'll do one step apply solder to all these pads first and then I will go and place my resistor and then tack it down tack tack the resistor down onto each pad as a second batch step and then I'll flip my board around to the other side right or if you're left-handed if um ambidextrous you can solder with both hands you can know then you go through and you complete the joint on the other side so that's a batch process but I'm gonna show a single resistor today now we are going to need any flux for this because there's that flux built into this art so into the core of the solder here so let's actually just apply a small amount of solder just a tiny amount onto that pad there and that will allow us to tack down this component so if we grab it with the tweezers like this and we get in there it's important to what make sure the component doesn't flip up like that's hard on the camera I can't get my tweezers down vertical but if I get my resistor in there and I just reflow it like that and really we've soldered one side of the resistor there beautiful and we just flip our board around like that and we go in grab our iron again and get in there with our once again I'm using a very fine soldier nor point four six millimeter solder tiny stuff I highly recommend you get that size or smaller for this kind of service mount work forget using point seven or one millimeter solder really you into a horrible job you've got to feed too much solder in there it'll it'll just look very amateurish it'll be horrible trust me spend good money get good quality fine solder and we go in there and we just there we go we just tacked down the solder the other side of the component and bingo we've sold it and oh six oh three surface-mount resistor and it's the same for a capacitor is the same 404 oh to size 1206 Oh 805 whatever or it's um also very similar for other components like a sock 23 and things like that so it's really quite easy to solder these components give it a try piece of cake and after you've soldered small parts like this you just want to get in there with your jewels looped one of these or your inspection microscope or something like that and just check that that the resistors are soldered nicely just and once again it as with any solder joint should be nice shiny night very nice shiny and smooth finish and you should have a very nice fill it there on either side of the resistor that one there slightly crooked a little bit off-center but generally that's not a bad job at all okay now let's try and solder this a very typical our 8 pin s o package I see here very easy to do by hand even if you're not even if you haven't done SMD soldering at all because the pin pitch is that reasonably large it's um half that of a standard dip based IC instead of point 1 inch it's point O 5 inch or one point two seven millimeter pin pitch in the metric scale and that's actually quite large and you can get in and with your soul through nine and actually individual and solder very fine solder and solder each individual pin this is one way to do it do it there are other methods as we'll see which are better used on smaller pin pitch parts but these Esso packages I like to just dump solder each in a bit individual pin by hand with my iron and how we're going to do this is we're going to use the reflow the attack and reflow soldering method so I'm going to put my iron on there and I'm going to just start in that little pad there it needs to be sort of you know every a small sized lump of solder on there it's you you don't want to turn it completely flat because then there won't be enough solder on there to actually tack down your component and the whole idea is that we want to bring in our component this is where our our tweezers can come in handy and we want to actually tack that pin down on there like so and that holds our chip in place and we can solder the other pins flip that around to the other side and we just want to solder the diagonally opposite pin so you get your iron in there chisel tip which heats up the pin and the pad at the same time and just apply a small amount a solder in there and it will you can it will just flow onto both the pin and the pad and you should get a nice a very nice fill it in there it's hard to get I can't really zoom in much more than that but you should get a really nice shiny finish as well with no burrs and no things sticking out no shorts to other pins because we've got the solder mask on these boards solder mask is vital for surface mount our soldering work this is the red material that you see on the board but it also comes in other colors you've seen that green and there's blue of there's black and these yellow and there's white and there's all sorts of colors that you can get but solder mask is vital because the solar mask will actually go between each individual pad like that and it will prevent it will help prevent unless you're really bad at solder in prevent shorts between the individual pins and that's really important as we'll see on the much finer pin pitch components but as you'll see I can sort of you know solder all I want I'm trying to attempt to put solder under this bottom this solder mask it will blacken but it will never ever take and by having the solder mask in between the individual pins like that on a board it just dump helps keep the solder out because it's not sticky at all the solder will just naturally want to flow into the individual pins and not get stuck between the pins I sell I am there once again for a second or two just like a through-hole work and apply the solder not to the iron itself although it's hard when you're this sort of pin pitch but apply it to the pin or the pad if you can get access to the pad and it will flow onto the joint like that bingo we have one side nicely soldered and with practice you can do this incredibly quickly just as quick or even quicker than not through-hole work and then we'll get in there with our jeweler's loupe and we'll just have a look to make sure the solder joints are good and we can actually see that there's no shorts in there and as you can see I've got a little bit of solder splash onto this pad here you've got to be careful not to do that it's because I'm working under the camera here and I had to use a shallower angle the soldering iron the shallow a shallower angle than I normally would but as you can see those joints have turned out quite nice because I've used 0.46 millimeter solder I've used a nice site chisel point soldering iron which allowed me to hit the pin and the pad at the same time I was able to get in there nice and quick and then is a nicely salted surface mount chip and it really is easy give it a go now let's try and solder a much smaller pin pitch of Nohr point six five millimeter pitch device let's see how we go and remember it's got the solder mask in between the pads let's start out by tinning one other pad shall we there we go and this will allow us to reflow what's called a reflow our part into position because this is the reflow soldering process because there's already solder on the pad itself and all we do is heat it up be it with a soldering iron or with an infrared reflow oven or a toaster oven as you may be familiar with a lot of people use those and this is how they must assemble boards after there's pick-and-place them using the reflow process we've done a very similar thing here or an identical thing but we've just a used a hand soldering iron and with this pin pitch I'm not actually using any visual magnification at all I'm viewing this on the camcorder screen here but I can solder these by eye okay let's try and tack down the other corner here sherry if we can get in there there we go I think we've tacked down the other pin so that chip can't move any more it's secured in place and consulta the other pins even though my alignments a bit off there I may need to work reflow that and just shift it slightly so there we go just reflow that and just move the chip gently into place until those pins line up perfect now there's one thing I forgot to use here and this was the flux pin I'd probably should have with these surface mount parts these surface mount ICS like this I probably should have that just pasted on a bit of a layer of our flux before actually onto all the pads before I soldered that chip into place but I'm just going to apply some just after the fact here I'm just going to work with that a little bit on there so to help the solder take to that when I drag it right across with my well-based tip and there you can actually see the residue the flux residue all around there like that I sort of overdid it a bit there but you can actually see it's in place too bad it's not actually under the pins but it could actually flow back under and that will be good enough should be good enough okay here we go let's feed some solder into well here until we've got just enough to sort of make it sort of just swell out the bottom and let's see if we can do this bingo look at that magic and there you go that's almost a near-perfect solder joint on each and every one of those pins and all I did was drag the soldering iron across actually dragged it across a couple of times because I didn't get it first go it's a bit hard under the camber and I haven't practiced mmm today which is something that you should do before you start out on an important board just even no matter how experienced you are just do a little practice run now as you can see we do have a tiny little bit two pins shorted together there but we can get our trusty solder wick this is the really thick stuff this is where the superfine stuff would come in and we'll just wick that away bingo gone and we have a perfectly soldered 0.65 millimeter pin pitch and I don't know if you heard that on the camera but there was a lot of that sizzle there as well as the flux are burnt and the flux is really the key to doing this I'll try and do exactly the same thing on the other side okay but I won't use any flux and let's see what happens and that one turned out okay there's one little solder bridge there which I can fix up with either the solder wick or I can just come back in with my Wiccan tip okay and just that will just suck that should if I can get in there suck that away like that now that turned out alright but it took a few err swipes it didn't seem as clean to me because the other side that had the flux on it just sent to a reflow much better I just much preferred that so the flux can be really handy unless you got like a brand spanking your board fully clean you've got a brand spanking new component and you know no oxidization then you can do without the flux but flux really helps but there you go that's how you can solder an 0.65 millimeter pin pitch yeah you'd have a hard time doing those are individually with each pin you'd probably have to do it under a microscope to get a good result but with one of these are well based arm tips these things that actually have the wool in them that wick the solder away these wicking tips are great now what we're going to have a go at is solder in this pic 24 F J not that it matters it could be any chip but it's a pic 24 F 0.5 millimeter pitch quad flat-pack let's see how we go first thing we're going to do is just put some flux on these pads now here's a liquid base flux if you want and really because we've got the gold flash pads here you don't necessarily have to use flux like this but I'm going to anyway because flux is always a good thing trust me it's the key to good surface mount soldering like this am I going to use our tack and reflow method here so I'm just going to put a little bit of solder on that second pin there because I didn't have to worry about getting it on the first one there and we're going to tack that component in place in at least two corners and we'll just reflow that pin there there we go and we'll just tap and we'll just tack solder a second pin there we can clean that up later it doesn't matter if we've got a short there and just to be sure we'll add some more flux along there because you can never have too much now the technique we've been using here is called drag soldering as you see we drag the soldering iron over the pins and I showed you it with a well based tip but you don't have to have a ball-based tip you can have a standard chisel like we've been using now what you can in fact some people will say it's better to use a chisel but well I don't know um take your pick really but we can do drag based solar in with a will with a regular chisel tip as well let's give it a go here we go we're going on or point five millimeter pin pitch part this is quite a very small part pretty much as small as they get so we've got some solder on the backside of that let's give it a go there we go it's not necessarily the cleanest result there because there's a probably a bit too much solder got on on the pins but we can actually clean that up you can actually drag the iron back out like that and get the solder off those pins no problems at all but look at that we've created we've soldered easily soldered an or point five millimeter pin pitch part and granted it's really easy if you've got these larger longer pads that you can actually get the iron onto so if you're laying out your board like this for these nine point five millimeter quad flat-pack it doesn't matter what size this can be a big two or three hundred pin quad flat-pack and you'll solder it just as easily and just as quickly and to finish off this chip you would just do exactly the same thing on all four sides and cleaned it up with a little bit of solder wick if you have to or as I show just dragging the iron back away from the pins now this one really helps because it's got really long it's a prototype board so it's got really long pads like this and I don't recommend you when you lane our footprints to make them this long but something like these pads over here is would be a really nice size exposed pad there so that you can get your chisel tip iron or the solder the molten solder the ball of solder either in your will or on your chisel tip so that actually makes decent contact thermal contact with the pad itself as well as the pen and then with the flux it all just flows beautifully and it all has to do with the surface tension of the solder because you know some people look at this and they think it's just amazing how you can solder an 0.5 millimeter pin pitch part with a couple of millimeter diameter chisel tip like this you would think it's impossible well it's not it's because of the surface tension of the solder it just wants to stay on the iron I'm Eeva I'll stay in the well tip or the chisel tip and it doesn't as we showed it doesn't want to stick to the solder mask the red solder mask material which is between the pads and it wants to actually just reflow onto the pads itself with the flux there to help clean it so really it's it is almost like magic and there's no trick to it at all it really is that easy and if you don't feel comfortable actually dragging your iron all the way along these pins especially the very large packages you don't have to actually drag you along you can actually just drag are the individual pins and backwards as we saw like this you can actually just get them like that and just touch it in like that if that's another technique you can use it's not as quick and efficient but you can actually say that it is a bit it's a bit more precise than the technique of dragging them actually across the chip like that so you can drag back at my total a little bit more but you can actually get a bit more a bit more precise feel and there you go just that simple application of the iron and we have pretty much perfectly soldered one side of that quad flat-pack and as with any solder joint each one has to be a really nice shiny joint with a really nice filler it's really hard to get sorry I can't actually zoom any closer like this under the camera but you can see that really and that only took me a couple of seconds and each joint is pretty much almost perfectly formed and as I mentioned in the first part of the tutorial my soldering iron there is set to about 350 degrees you certainly wouldn't want any higher than that anywhere from 300 to 350 is is really going to do the trick for for fine surface mount work like this because if you make it too hot you can actually lift the pads you have to be careful and especially if you apply too much pressure with your iron if you come across here and actually apply a lot of pressure as you're sweeping across like that you can actually lift the pad so just be careful that you apply very light pressure and in the case of the well-based abused you really shouldn't even need to touch it as long as the the molten ball of solder actually makes contact thermal contact with the pen and the pad it's going to reflow so really you should shouldn't be having any pressure at all on there if you are just very very light there's another technique that some people like to use and you can actually use a solder paste this is just some basic cut solder paste with a little arm in it in the syringe like this and you can actually just apply a small amount of our solder paste ever even before you lay the chip down or you can even do it after which I'll show an example of here but you really have to get just the right amount of paste on there otherwise you end up with too much and then you've got to clean it off but anyway let's give it a go let's see if we can apply a small amount of paste across here it's good it's quite hard under the camera here but anyway let's give that a go and see what happens and you can likely hear that I've got my hot air gun here it once again set to about 350 degrees and with a reasonable airflow on there and let's heat up this and see if we can do it normally I'd get this write down vertical but I can't do that with the camera in the way unfortunately go on this but it should there we go there we go it's finally reflow in bingo and that's not a bad result I'd say is slightly too much solder paste there as you can see it's actually quite hard to dispense the correct amount of paste and of course this way this is where you get into what solder stencils and proper reflow solder in with a thermal oven which won't be in this tutorial because this is about our hand soldering it's not about doing a solder paste stencil but um that there you go you can actually use a syringe based paste it once again you can go along with your iron or your wick later and you can actually clean up that generally you're going to end up you usually going to end up with that more solder than not generally it's it's hard to put a very tiny amount on there unless you've got a specific paste dispenser you can get automated up pump based dispensers they only dispense a certain amount of paste and you can go along and actually apply it to each page and go long and go bang bang bang bang on each pad like a little drop just before you place the chip down but geez if you're going to do that well you probably may as well do the UM stencil as well but there are some cases where you actually want to rework boards with components all around where you can't actually get in there and do a solar it's not as easy to use one of those up solder paste stencils so you may have to use one of those pump solders paste solder paste based and dispensers to just dispense the correct amount of paste on each sharp pad and you can actually get machines to do that as well and I've got another video which I'll link to here which actually shows you a very expensive high end machine that can actually dispense paste onto individual pads in a fully automated type process that's good for reworking BGA components and things like that now you'll notice that I've been using a gold-plated or a gold flashed prototyping board here now if you're going to do really high density fine surface mount work I highly recommend that you get your boards manufactured with these gold are flushed pads because it is just that a it's easier to solder to everything takes better the flux takes it you don't have to use as much flux it's just nicer it doesn't it doesn't corrode as much and it's just done and the other thing is that it is a much flatter surface and that's quite important when you get down to quite fine pin pitches you can get finer stuff than this and if you get BGA's it's actually quite important that you that that the chip actually sits on all the pads quite flat now if you compare that with a what's called a hot air level um solder finish board here's a typical one it's not it's not the gold flash it's just a solder a template solder finish on the pads here and you probably can't see it under the camera there but the finish is uh it is lumpier and um and the chip doesn't sit as flashing if air flush um it's flat to the board and if you've got like a BGA or something like that with the little balls in there um if you just get one pad that's got a bit of excess solder on it then you're going to get a horrible result so really it doesn't cost all that much more you know it might even cost a few cents per board really to get the the gold flash pads I highly recommend it now let's try and solder on this a higher thermal capacity Deepak here the others have been really easy because our soru nine hasn't sweated the smaller stuff at all but as you can see this some large rather large device has a huge pad on the bottom and a matching pad here which is connected to a edge well it's a reasonably large art little heatsink here as sort of a heatsink ground and so let's solder that in place and see if we can do that at the same solar in temperature we use before 350 degrees C with the same chip now to our chisel tip we used before and see how we go on that see how long it takes to solder something of this thermal capacity and of course we're going to want to have to tack this in place as well so we'll just put a bit of solder on that pad there and we'll just bring our device in and we'll reflow that in place no problems do the other pad now as you can see we don't actually have any pad area there to actually apply our solder to our ball our int so we really have to apply put the iron on top of the leg apply pressure and feed in solder from the bottom like that and it reflows on to the pad and then on to the leg as well now I'm going to use my standard Dutch is all medium sized chisel tip here I still got my own set to 350 degrees as we've been using up until now but I've got this large amount of copper listen let's see how it goes now one method to actually do even what larger devices like this and this is actually quite a small device a Deepak I mean I forgot a large to-220 and trying to solder to the tab or something like that you may actually want to preheat it now what's called a pre heating process where you would that's where your hot air gun might come in handy you would actually heat up all of the surrounding copper and the pad and the component first and then you can get in there with your solder and require less time but anyway let's say let's not discuss that today let's actually get now iron in there try and get it on the pad and the device as well at the same time and let's try and get our solder in there now at the moment you know we're trying to apply it to the pad and that's really not working that well this is where okay we're going to have to put some solder onto our on to our tip like that so that where we can actually better thermally couple onto both the pad and the device so we've now got solder on there and you can see it already starting to flow on to the pad and there we go bang starting to flow along and it's starting to heat up both but as you can see it's taken a bit of it's taking a bit of effort you can actually see parts of it cool while the others actually heat it actually heating up and is molten the other end of it just instantly cools and solidifies look at that but there you go we've actually now completed that but this is actually this isn't ideal because it's only actually attached to the top we haven't actually refloat any under the bottom this is where arts some thermal paste would come in handy to actually put some paste on the bottom of that device and then you would actually reflow that with your hot-air gun on top but anyway that's that's not that's ok for just a simple art prototype but of course I'm not entirely happy with that look it's it's it's all lumpy and it doesn't you know it's all craggy I don't like it it's not as shiny as it should be so let's get our iron back on there shall we try an air we try and get this one flat to apply a much much more even heat so we'll leave it there for five seconds or so and we can heat up both the pad and the device and this is where we might want to turn our temperature up a tad but as you can see where I'm already starting to get a much better out a much better wedding between both surfaces there and we've probably got a little bit too much solder there actually so it's not going to look perfect but that is better than what we had before and there you go that is quite a nice shiny smooth result there and that device is still hot it's still very hot after the process but these larger components can actually take more of the heat like this and they will actually trap the heat for longer so just don't be careful not to touch them because after you've solder them because they will still be hot retaining that heat as part of the thermal capacity that's their job now if these are small components like this these passive components they can be quite easily damaged by excess heat you have to be very careful with them it could be because there's no thermal capacity in there at all so so most of the temperature of your iron is going to go straight into that component very quickly our multi-layer ceramic ceramic capacitors are one example of components that can be really damaged out very easily with excess heat so you want to be very quick and you want to use as lower temperature as you can get away with with these devices and otherwise you can lift the end caps off them and and your boards as well your fr4 PCB material you can get different temperature grades which will handle heat better than some will handle heat better than others but if you've got a poor quality if our for material that uses poor poor quality glue and resins and things like that to actually stick the copper down to the fr4 for material they're numb really you and these pads can actually lift straight off the board if you have excess heat or leave it there for too long so just be aware of that let's actually see if we can do that I've turned the solder and iron up to 450 degrees Celsius and I'm going to heat up this pad here now it could take a little bit and especially it does it a lot when you are when you're doing rework and stuff like that if you have to rework out several devices but there we go bingo it's gone there we go we've lifted check it out we've totally lifted that pin up to bug it look at it see it's just totally floating and hanging on to to the trace like that thank goodness that the copper actually still hangs on there so you can actually if you're very careful you can actually push and push those back into place if you do lift them can push it back into place and then still solder your I see on top but you could be careful of that that's what had can happen with two higher temperature I told you it was easy look at that point five millimeter pin pitch parts why be scared of it he'd do it in a couple of seconds with her which is very basic tools and hardly any experience at all it's unbelievably simple now we didn't cover our solder stenciling which is a different technique and put it in the reflow oven and things like that maybe we'll cover that sometime in the future but this is just hand soldering and you need good hand solder in schools even if you're going to stencil and reflow your own boards cos sooner or later you're going to have to rework our parts and rework solder in techniques are slightly are different as well especially removing parts maybe we'll do another tutorial on just reworking parts but hand soldering skills very important and there's no need to be scared of any components like this surface male components are easy to do basic chisel tip soldering iron some fine solder a well-designed board with well-designed pads and the solder mask make sure you get the solder mask between the pins when you're laying out the board watch for solder mask expansion go Google that too I think I've probably done that in a previous tutorial solder mask expansion is important to get that right but if you get those things right you can solder all these boards yourself at home very quickly very professionally simple basic tools so there you go I hope you learned something and go out there don't be afraid of surface mount parts they're a piece of cake see you next time and don't forget your flux fluxes everything

Channel: EEVblog

Views: 1,272,360

Rating: 4.8370504 out of 5

Keywords: soldering, smd, iron, tutorial, hot, air, surface, mount, paste, wick, station, pcb, board, resistor, capacitor, ic, chip, TQFP, BGA, reflow, flux, how, to, tip, electronics, diy, oven

Id: b9FC9fAlfQE

Length: 39min 55sec (2395 seconds)

Published: Fri Jul 15 2011