Hi. Here's a real trap for young players. Look, what can happen to an already populated PCB if you try and reflow it in a thermal oven? Hmm I don't think our connectors gonna fit anymore. Oops.

Look, what's happened to all these through-hole connectors on this Samsung dumpster-dive 56 inch LCD TV I've got Wow look at that just melted them. Ah Horrible. Look, The flat flex connector survived just fine. Why is it? so now as you saw in a previous video and if you haven't, I'll link it in down below.

Check it out where I tried to repair this 46 inch Samsung LCD TV I got in the dumpster and I successfully reflow the T-con processor board here in my reflow oven. No problems whatsoever. Unfortunately, it didn't fix the fault, but I didn't actually damage the board at all. So I thought and you know I'll reflow the processor board.

so I took it out, whacked it in my reflow oven. Exactly the same thermal profiles What? I use for this T-con board and that's what happened. Mmm. bummer.

So why was there no damage to this T-con board at all? even though it's got a very similar looking connector up there. but this one just melted all of these connectors right along the edge here. Well, if you'll notice, these are actually a through-hole connectors on the bottom here. I've actually D soldered a couple of them, but you'll notice that these are all through-hole connectors.

Every single through-hole there's four of them and they all melted on this board. whereas the T-con board here survived just fine. But you'll notice this connector at the top here is not a through-hole connector. it's actually a surface male connector.

And that's the key to what's happened here because as a general rule, surface mount connectors like this one even though it looks almost identical this one, apart from all the melting, is that these surface mount ones are design and using higher temperature thermoplastics to actually survive the reflow soldering process used in surface mount boards like this one. And likewise with this high-density ribbon cable service mount connector. It's designed with plastics which are designed to survive the temperature profiles and these through-hole ones are clearly not as higher temperature are rated or for as long. They might survive the same peak temperature, but these are this particular type or brand or model or whatever might actually survive them longer then these particular through-hole ones here Because when you sold a through-hole components, of course you're only heating the individual pins on the bottom of your hand solder or if your wave solder.

And of course there's a big bubble in solder wave under the bottom here which then goes along and heats up all the individual pins and the individual pins are getting hot. They can get just as hot or hotter than the entire connector here, but that is the difference in a reflow oven. The entire connector, including all of the plastics, is slowly brought up to temperature, slowly rises up, gets hotter and hotter, and all of the plastic gets to that temperature self. They're not designed to survive it like these ones here clearly aren't then.

oops, That's what happens. But even if you're buying proper surface mount connectors like this supposedly designed to survive the reflow soldering process, you can still have issues. Now here's a photo of amps and connectors which are at a former company. We bought these connectors and look what happened to them.

They just melted. These are right angle through-hole our pin headers that were supposedly designed to survive the reflow soldering process. but this particular batch we got weren't I Don't know. they might have changed the plastic mixture or whatever happened.

Supposedly we got them from the same supplier I Don't know. he might have got duped, might got it. might have gotten a cheap, you know, clone rip off our parts from the Shenzhen market or something, but that's what happened from one batch we ordered. Another batch worked perfectly.

So yeah, you know it's all to do with the type of plastic and the temperature. our raiding of the place it's used in the connector. Now here's a typical reflow temperature profile for summer lead-free solder paste. This comes from a previous video which I've done.

so click here if you haven't seen that where I actually use the thermal oven and reflow the boards and get some data logging plots of my oven here. And basically you know there's all these different. They're separated into different sections, but it basically slowly ramps up like this hits a peak and then cools back down basically almost as fast as it can possibly. So you're the reason that it's like a big thick like that is because this is like the temperature range.

The acceptable temperature range for that particular solder to operate in, and each particular type of solder is going to have its own type of profile. Different parts can have different temperature profiles you'll often see. There are temperature profile recommendations in component data sheets as well, and likewise for surface mount components. Here you go, look up the data sheets firm and you'll likely find a thermal profile for some of the better manufacturers.

For example, here's a data sheet for a High Rose, which is a pretty reputable manufacturer of these type of connectors. The DF 13 series. Look Here it is recommended Temperature profiles. You can see the preheat in our phase.

Here these are the different phases I was talking about of the soldering process. And look at this look: Max 230 degrees here for 60 seconds soldering If it goes over 60 seconds, all bets are off right then. they don't basically do not guarantee that. and and it tells you down here as well in this table, look more than Tintin Solder in more than to stand 20 C for 10 to 30 seconds.

So you know if you go over that the things can melt and it doesn't take that long at all. You know you could go 10 seconds over and that could be the difference between your connectors melting and not melting. And here is the actual temperature profile. Maybe to lay out our thermal oven which I captured with my Agilent data log in multimedia and up.

this is a tablet shot I did this in the previous video You can see you know it ramps up sort of in a similar kinda way and it reaches you know, a P temperature 230 or 240 degrees or whatever it was and then. But the problem with these type and types of Cheaper do-it-yourself ovens, especially the ones that aren't fan force. They can't cool down very quickly, so if you don't open that door quick enough and sort of can I get all that heat out and sometimes just opening the door is not enough. It can stay there for too long and look, we're talking.

You know you can stay there for it like a couple of minutes, right? That's will over the data sheet values for these sorts of things typically. So yeah, all bets are off. As I said, you don't know what your particular connectors are going to do unless you've got the correct data sheet and some data sheets don't even tell you all that sort of stuff. So it's all pretty hit and miss.

But basically yet, you've got to not try and keep them at a hot temperature like this for too long. Just the absolute minimum required. so it's a really fine balancing act. So in the case of this board here, we just got unlucky and well, you know you could have thought that Well, okay, these are through-hole connectors.

Maybe we should take care. I actually, by the way, put the board in like this. so these connectors were at the front. so I couldn't even visually monitor those connectors at the back here.

So you know if I really had my brain in gear and I know this stuff's I should have like gone. Oh yeah, okay, should be extra careful with you know these through all connectors. maybe there's some issues there or something like that. put them at the front, really start to monitor them, but by the time you start seeing it melting, it's probably too late.

So yeah, yeah, oops. just completely come a gutter and our data sheets for this ite connectivity one. for example. this is a three typical through-hole boxed pin header like this and look, it's wave solder capable.

Okay, it doesn't say anything about reflow at all in this datasheet. So unless you specifically went and asked the manufacturer that you know, you just don't know if this is compatible. We say the yeah pasty in pin soldering process and that's here's actually a shot courtesy of Phoenix connectors. They've got a like an uploader thing on this and this shows how you can actually reflow solder regular through-hole connectors using a reflow oven process.

You actually put paste inside the hole, then put them the connector in there reflow like a surface mount component. But if you use one of these connectors which doesn't have the high-temperature thermoplastic in it to enable that and it's only wave solder compatible and you haven't checked, well, you can come a gutter just like this. So the moral of the story? Just be careful using these cheap-ass do-it-yourself thermal ovens. They're not that great.

they're not that precise, not that controlled, and just be aware that you can actually have problems like this. And in this case, I was probably a bit gung-ho You know, a just reflow the T-con board and it just survived. Fine and dandy. So I just wait this one in Not giving it a second thought.

Don't silly me, through-hole connectors on the side because apart from that, everything else on this start processor board survived just fine. It was just this right angle connectors. in this case, the particular type of plastic particular connector. Who knows who the manufacturer is, who knows where they sourced them from.

They just didn't like it because this board is. They almost certainly soldered this thing using a weight like a two step process. They did the UM SMD reflow stuff of course, which is you know 95% of stuff on here. and then they put it through a dip solder in our process.

a wave soldering process where it all bubbles up underneath and solders these connectors on the edge here, so it was actually able to de solder These things are pretty easily using my desolder pump, so yeah, probably ultimately are repairable. It's not too big a deal, just melting some connectors like this if I can get replacement ones or or an equivalent one and just sort of budget it in I could even like individually take out the pins and just solder the pins back and just sort of budging the connector if I was really desperate. but yeah, it's just a little lopsy trap for young players. Yeah, I got caught out.

Hope you learned something useful out of that video. and if you liked it, please give it a big thumbs up and discuss it on YouTube and over at the blog and everything else. And by the time you see this, I've probably got a new website over at Eevblog. Calm as well.

that'll be like I'll slowly be adding more features and stuff to that over the next month or two, so check it out. Hope you enjoyed it. Catch you next time you.