Hot air gun solder. Completely useless - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: May 20, 2024, 08:08:45 pm
content: Hi guys, it's been a while I've been trying to solder stuff with solder paste plus hot air gun.It's always been a disaster. No matter how low I set the air speed (20% now), small stuff (0805 or smaller) keep flying away, and I have to crank up the heat up to about 330°C to even have the chance of the solder melt.I'm using ChipQuik solder paste now, but the result is the same. So I think I'm doing something wrong. Do I use the big nozzle or the small one for soldering onto a board? Any videos or pointers on how to learn?I'm planning on doing boards which feature some… challenging packages and I was counting on the hot air gun to solder those, now I'm lost!Cheers

author: ejeffrey
author_rank: Super Contributor
timestamp: May 20, 2024, 08:23:11 pm
content: Yeah, don't use hot air guns to solder, it doesn't work. Use a soldering, a a hot plate, or an oven.Hot air guns are good for desoldering and rework. Another way to use hot air is with a hot air table that blows hot air onto the back side of a board. This is good mostly for preheating a board: for instance, if I'm going to solder some connectors to a board with heavy ground planes and no thermal relief, I will often use hot air to warm up the ground planes so they soldering iron has an easier time.

author: IanB
author_rank: Super Contributor
timestamp: May 20, 2024, 08:31:03 pm
content: Also, whatever hand soldering method you are using, you should hold the part down with something to keep it in place while you apply the heat to it.

author: dmulligan
author_rank: Regular Contributor
timestamp: May 20, 2024, 09:26:36 pm
content: Louis Rossmann did a video about this a while back. It might be how you are holding your parts.https://youtu.be/gl9NuCiDR7s?si=bd5o8gEajWHfcBQV

author: JustMeHere
author_rank: Frequent Contributor
timestamp: May 20, 2024, 09:43:16 pm
content: Quote from: ejeffrey on May 20, 2024, 08:23:11 pmHot air works and is fairly easy. I prefer it over the iron.Work in circles. Make them smaller as you get your work aera up to tempature. I tack down small components with flux.

author: shapirus
author_rank: Super Contributor
timestamp: May 20, 2024, 10:00:38 pm
content: Quote from: Moriambar on May 20, 2024, 08:08:45 pmStill too high air speed, I guess. Or maybe you hold the nozzle too close to the parts.I have one of those cheap (but good)Yihua 8858hot air guns and am having good success with soldering SMD parts, including small ones. Settings: air speed 15% or even less, temperature 360 °C or even more, calibrated using a DMM with a thermocouple. High temperature, I believe, is not much of a problem, as long as I don't hold it there for too long: basically just enough to melt the solder, and in some cases to give the part a little push or two and watch it snap back into place to make sure it's properly seated.Preheating (just hit the board with hot air from the bottom for some time) also helps.Regarding high temperature: I've had some ICs that I initially soldered with an iron, then desoldered using hot air at 360 °C, then soldered back again with an iron. Of course I can't be certain that they definitely weren't damaged, but at least they kept working as expected. As a matter of fact, I have never made a semiconductor component non-working during soldering or desoldering. Whether I created any subtle damage, I do not know.

author: Moriambar
author_rank: Unknown
timestamp: May 21, 2024, 07:46:38 pm
content: thanks everyone. I'll try applying your suggestions.Hopefully I'll be successful next timecheers

author: JustMeHere
author_rank: Frequent Contributor
timestamp: May 22, 2024, 05:38:34 am
content: Practice on a dead something (computer, alarm clock). Work on removing different components. Then add them back. If you can do that on a commercial grade board, then your own project boards will be easy. A board with ground/power planes and lead-free solder will be tricky. Figure that out and the other stuff gets easy.Sometimes hotter is actually cooler....how? Because if you have your iron too cool, it heats up the entire component instead of just the leads. So if you find 330 is what works, use it. Just because your air is 330, it doesn't mean you have to heat up the component to that temperature. The solder will still melt at ~200 even if your iron is on 400. So, get it hot enough to melt the solder. Linger for a second or so. Then pull away gradually. And you will be fine.By using a hotter tool you can get the job done faster and end up heating the components less. If have ground/power panes, remember they will be sucking heat away from the work area. So heat it up faster than it can be sucked and less overall heat is sucked away.

author: nali
author_rank: Frequent Contributor
timestamp: May 22, 2024, 07:37:48 am
content: It might also be your hot air gun. My first air station was a cheapie and used a diaphragm type air punp which gave pulses of air not a smooth flow, and I was experiencing the same as you with components 0603 or below being blown away, even on the lowest airflow setting. Now I still use a budget model at home but the fan-in-handle type which although a bit more unweildy gives much better results (most of my discretes are 0402 now).Also... get a preheater. You won't regret it.

author: perieanuo
author_rank: Frequent Contributor
timestamp: May 22, 2024, 08:01:01 am
content: hi, don't think for one sec that 330C you see is 330C on the component. just attach a thermocouple near the component solidar with the pcb and you'll understand what temp you need on the handle to get the 255C on the pcb. i have colleagues using daily this technique on ic's, passives of all size, it works. the paste just need to be medium quality.personally, i prefer big machines because i have them on hand (ie ersa 600), but in a hurry the hotair handle for 0805 (this is BIG those days, we change smaller passives) is ok