 All right well let's just get started early. This is not a long talk. He's got me slotted in for one hour but this is not going to take an hour unless you all have a lot of questions so so soldering uh well soldering 101 melting metal for fun in Providence. This is an actually an old soldering iron from back in the day. It actually had gasoline in it and then you would pump up the gasoline under pressure and then that was the torch uh and then the the soldering iron was just that top part and that that was loose that just came off you would solder with that. It was more for soldering like metal and cans and they used to actually solder food cans which probably wasn't a good idea so all right so solder is uh a an alloy of uh tin and lead for the most part. There are non-lead solders but this is your basic solder. If you're just starting out you probably should stay away from the lead-free solder because it's actually a little bit harder to use. There is a thing called the eutectic point of bimetal alloys and what that means is that point that the melting point is the lowest so looks like about 168 Celsius. That's the eutectic point and at that point something special happens. A bimetal alloy will melt and turn into a mushy state if it's non-eutectic but if it's a eutectic alloy it freezes all at once it doesn't go through a mushy phase so that's good for solder because you want it to harden all at once you don't want it to mush around while it's hardening. So most solder is 60 40 and that's very close to the eutectic point but it's not not exact and the reason for that is that tin is way more expensive than lead so they they shifted a little bit toward the lead side to save a little bit of money. So the non-lead solder the reduction of harmful substances solder is a tin silver copper and that gives a much well it gives it a little bit higher melting point makes it a little bit harder to use and so that's why you know if you're building 10,000 of something and they're going to wind up in the landfill you know use lead free solder because then it matters but if you're just doing hobby stuff just use the lead and solder. So flux flux is is flux is what makes solder work it's it's abiotic acid it's called rosin flux because it comes from a tree it's rosin but abiotic acid is what makes it work and the way that it works well actually so flux is at the core of most electronic solder so it's right there you can see it you can't hardly see it when you're actually holding the solder but it's in there so when you put the solder on the iron you see a little bit of smoke that smoke is actually the flux melting and burning if you leave it on the iron too long all the flux burns off and then you're kind of screwed because flux is what makes soldering work. This is the good stuff the paste flux you can you can sometimes get that bomb they've actually got these syringes of flux so they're actually over there if you need them but these are these are nice because you can just squeeze out a little bit the the pots are more for dipping your iron in you know just getting a little bit of flux but these are good for applying to the circuit board. So this is rosin flux in its crystallized form it's sort of what it looks like naturally you can use it in that form but it's easier to use the paste so some of you may remember this scene from Fight Club and the reaction involved here is relevant to soldering because this is a saponification reaction it's sodium hydroxide like combining with the fat in this man's hand forming a soap and so that's actually what flux does as well it's a saponification reaction it's another soap slide I'm not sure why I have two. The saponification happens with the copper oxide that's on the surface of copper in the contacts the abiotic acid reacts with the copper forms copy abiotate which is actually a soap and that that causes the surface tension of the solder to decrease it causes the solder to actually stick to things because surface tension is the key to soldering. Use plumbing flux that's a harsh acid flux abiotic acid is a weak organic acid plumbing fluxes are generally a stronger acid they're going to cause more corrosion over the course of the lifetime of your your device if you do have to use a plumbing flux we'll rinse it off thoroughly you want to use the rosin flux if you can the electronics flux a lot of it this is no clean flux or it might say force surface mounted or things like that that's that's what you want so the surface tension is critical this is an experiment it's a lead and frost effect you wet your hand you can actually jam it into a cauldron of boiling lead and it doesn't burn you liquid nitrogen yeah yeah so you can actually put liquid nitrogen in your mouth and it's the same thing but with the lead what the boiling water keeps the lead from sticking to you so that that's the key is that we want the lead to stick to the work when we're soldering and if it doesn't stick and lead doesn't like to stick to things it doesn't want to wet things so that's what flux does this is your basic iron a lot of people ask me what's iron to get it really depends on how much you want to put into it this is your most basic iron ideally you want to do a little higher than this but if you're only going to occasionally solder this is better than nothing the main problem with it is there's no temperature control so this is a slightly better iron it's still not great but it's got a knob there you can actually control the temperature so you don't want it to be too hot because then then you can cook things on your board you can lift pads you can actually destroy the epoxy that's holding the pad on the board you don't want to do that and if it's too low then you can actually cook pads as well because it takes longer to get it up to temperature if your iron is too low this is the iron I recommend if you want to spend like between a hundred and two hundred dollars it's a it's got hot air on one side and soldering on the other this is actually my my personal iron well I didn't take this picture but it is the model of my personal iron it you can get these on ebay they're they're made in china but they're actually pretty decent bomb that has one right there in the corner of the table if you want to check it out after the after the talk the hot air comes in handy and also it's got really nice temperature control for both the hot air and the soldering so what does a good solder joint look like these here on the left these are pretty good they should be concave and shiny if they're convex they convex is okay that just means you use too much solder but it can't hide little flaws like that bottom picture that let the little bubble is being hidden by all that blob of solder so you want to try to get it a nice convex shiny joint if you can and if it doesn't look shiny add some flux because flux will make it shiny it'll it'll reduce that that oxidation and make it shiny again what happens is if you're using flux core solder if you start playing with it a lot if you if you keep messing around you're going to burn all your flux off and then you'll get a joint that looks more like the ones on the right or especially the bottom two that's what solder looks like without enough flux it gets bumpy it gets the inclusion of corrosion in it and the flux will smooth it back out make it shiny again you could actually reuse that solder if you put enough flux on it and so you don't want the extreme overheating either and then like I said they're gonna actually be caused by an iron that's too low can overheat or it's that's too small of a wattage a larger wattage iron will actually tend to overheat less because it can get enough heat in the right spot where you need it fast enough to not heat the whole board up in the time you need so like I said it should be slightly concave it should go all the way around the pad and it should have a shiny finish if it's a double-sided PCB the solder might show through on the other side that's a good thing if it does you want it to show through on the other side so this is the sort of fake animation of the process this brown thing is the pad the wire is the yellow thing so you don't want to have too much solder on your tip because that solder is already devoid of flux it's already burned all its flux off you don't want that it went just a little bit of solder on the tip and what that does is it gives you a more contact area so you can actually get the heat where you need it quickly so you don't want a completely dry iron you want to have some solder on the iron but just very little so stick that down there so it's touching the pad and it's touching the wire that's important you want to heat up the wire and the pad because otherwise it's going to stick to it's going to stick to the thing that's hot and not stick to the thing that's cold and you don't want that so then try to feed the solder in from the other side and don't try not to feed it directly onto the iron because that works sometimes but it's not as reliable if you feed in from the other side then you know that everything's hot enough and it's ready to go and everything's gonna flow perfectly so you're feeding solder in the solder sticking to everything it's good you take the solder away but then you leave the iron on there for just like 1001 just one second leave the iron on the joint after you take the solder away that makes sure everything's flowed everything's hot take the iron away and ideally you get that nice little concave concave joint and that's what you want okay so in that one the flux was actually in the core of the solder this you see my mouse that brown there so the flux is in the solder you can also put a little bit of flux on the board if you want if you've got solder on the board that has already dried up you know it's starting to get that wrinkly look then you need to add a little bit more flux is that any other questions come on i got a whole hour you gotta have something this that that's the actual solder so the solder if i could find it the solder is actually like a hollow tube so the solder looks like a little hollow tube and it's got flux in the center and then it's that lead tin alloy around it so that helps you bring the flux straight to the joint the flux core solder prevents you from having to constantly put it flux on there to make things work but it's not foolproof so it's good to have extra flux it's it's hard to actually put too much flux and if your board does get sticky all you have to do is take some isopropyl alcohol preferably 91 percent and scrub the whole board and you can get all that flux off so flux off yes oh i thought you had a question anyone else so there's all kinds of cool stuff there's there's the hot air station over there at the corner there's a soldering contest uh tie short he's got a short tie can't miss him he's on the end there he's actually doing a time soldering contest so if you'd like to try it's got easy medium and hard easy is like through hole medium and surface mount the hardest small surface mount and you can only do one person at a time but i think he's got some kind of prize wherever gets the fastest time on that so there's a soldering contest there's lots of soldering stations you can watch people solder and if you go in the vendor area or if you have something to solder you can come in here and find an iron and solder it so anything else we're done we're done okay i think we're done thank you