Can a heatgun be used to remove one component (or other ideas)?

Flashlight Modding and DIY Parts
1

Hi,

I have a “regular” heatgun (something like this, but not the same model: http://www.homedepot.com/p/Wagner-HT1000-1200-Watt-Heat-Gun-0503008/100048744) and I was wondering if there’s a a way that it can be used to remove an individual SMD part, like say, a diode, from a board?

The last time I tried to use it to remove an SS34, I was able to do it, but it also blew several components around or off of the board.

I’m wondering if I cover all of the board with something like Kapton tape and expose just the component I want to remove if that would work?

Has anyone tried something like that, or has another idea/technique?

Thanks,
Jim

2

Plug it into a lamp dimmer... that will lower the heat as well as the fan speed, but if you're lucky it might still work.

3

Oo that’s a good idea. I never thought of that. Have quite a few motor speed controllers that could work with my heat gun as well.

Thanks

4

Hi comfy,

The one I have (I think the actual model is this one http://www.lowes.com/pd_20960-97-0503040_0?productId=1059297&Ntt=heatgun&pl=1&currentURL=%3FNtt%3Dheatgun&facetInfo=) has low and high speeds, and you can set the temperature independently.

I’ve used it mostly for reflowing emitters till recently, and I don’t know if I’ve just been too impatient, but when I’ve tried using it at the low speed, it didn’t seem to melt the solder, even at the same (highest) temperature.

It seemed like I always had to turn it to high speed in order to get the reflow done.

Maybe I should take some junk stars and emitters and do some testing with the lower speed again, but this time, wait longer…

Jim

5

If the temp & fan speed are truly independent, it should be hotter with the lower fan speed... air moving past the heater more slowly.

I have a Yihua 858D hot air setup, it's only 900W (claimed) edit: only 600W!, and I only need 310-320*C for everything, that's only 590-610*F. And fan speed low enough I've never ever not-even-once blown any parts off a board. If the specs on your gun are anywhere close to accurate, you should be able to light a PCB on fire with it when cranked up to max temp.

6

cheap 2 settings gun from ACE. No tips so made one out of aluminum foil for .25” tip. Works great as long as I can sneak up on single component with tweezers lurking in other hand. Pull tip off to wash whole board.

I have 10 amp Variac but could make do with heavy diode if I need to slow air and heat further. Still looking for 2nd hand hot air work station.

7

Nice unit!

You definately have to wait longer!

I have done reflow of components at work on all kinds of boards with simple on/off units. I cover what I dont want heated with tin foil and take my time doing it.

Changing a couple of diodes on a rectifier bridge in an expensive plc controller or something similar saves thousands of dollars and makes the boss love you.

8

Another potential option: I have a butane microtorch with a “blower” attachment (contains a catalytic grid) that can deliver moderate heat to a fairly small area. I haven’t tried it on any boards, but it seems like it would work.
http://www.bernzomatic.com/item.html?id=16

9

Single smd passives like diodes, resistors, and capacitors could be handled with just the soldering iron. Alternately heat both sides of device till melt point, at which time the device moves off one or both pads and holds to the iron, or can be flicked off with last dab of heat. Don’t have tweezers, but that would work too.

Another solution like for a multipad device like an ATtiny 13A, is to use ChipQuick which is a low melting point solder. Use some flux and solder braid to clean everything off the pads after removal.

10

Or you can just use that heat gun, set on high. I do it with a similar 1500W Milwaukee heatgun, fan on High, temp on 950 degrees. I typically hold the gun about 3in away from the PCB and move the gun around as necessary. It’s possible to blow components off the board if you get the gun too close - so don’t do that. It’ll heat everything up plenty from a distance. If you are removing a single component it’s best to secure the board and have your tweezers ready in your other hand. Remember not to jar the board even after you turn the gun off.

11

I’ve been doing some “practicing” on a junk/dead driver, and I really think that it either doesn’t get hot as fast, or it doesn’t get as hot at all, on the low speed setting, but what I found is that if I run it at high speed for awhile, pointing it somewhere else (preferably non-flammable), then after I see the front end starting to glow, change it to the low speed, then that does seem to eventually get the solder melted so that I can pull the part (and also reflow it back on).

Another way that seems to work ok, but only with boards that have the components all on one side, is that I run the heatgun on high speed (and max temp) and heat the board from the bottom for awhile, then, change the gun to low speed, and point it at the component from the top.

I’ve seen posts/threads about the Yihua or similar, and have been thinking about getting something like that, but I’ve been hesitant because I wouldn’t be using it that often. With the one you have, can you isolate the hot air to a small area (i.e., to cover just a single component that you want to pull or reflow)?

Thanks,
Jim

12

Making a small tip sounds like a good idea! The Wagner I have came with a couple of different ones, but even the smaller one is fairly large opening.

Could you post a pic of the one you made (and yes, I know it was from aluminum foil, but would still be interested).

Thanks,
Jim

13

Have you tried running it on high, but partially covering the air intake with your hand?

14

By “tin foil”, do you use just regular aluminum foil? Or is it maybe some heavier/industrial type?

EDIT: Now we know where your BLF username is from, like “LED” smoke :)!!

15

With the gun at 3 inches and at 950 degrees, does it take a really long while before the solder starts melting?

Like I said, maybe I’m being too impatient :(…

Also, with the gun that far away from the board, do you use like a really long pair of tweezers (so you don’t get burnt by the heat from the heat gun)?

16

Ouchy,

You want to hear something funny (like humorous)? When I first glanced at your post, I thought you were suggesting partially covering the front end of the gun “with your hand”, and thought “He has to got to be kidding!” :)…

More seriously, re. your question: No, I haven’t tried that. What would that do? Do you think that would decrease the velocity/force of the output?

17

Definitely!

18

I usually let the gun heat for 10-20 seconds before I point it at the board. I may have to get back to you on how long it takes. I’m pretty sure it takes over 5 seconds to melt the solder. I may be holding it close to the board than 3in, who knows. Since everything doesn’t melt at once, I’ve got plenty of time to adjust the distance as soon as stuff starts to melt.

I use 6in straight tweezers for the most part, or 6in bent tweezers. Once things are melted, they stay that way. It is merely uncomfortable to put my hand in front of the air at 2-3in, although holding it there will cause problems. I keep the tweezers away from the heat except when prodding the components or picking something up.

19

but now have to kill you all…

Fold sheet to length then twist to opening you want. Hold tip to barrel with wire clip or it could shoot across your desk! Just not sexy like a work station.

Forgot to mention poking diverter hole on top surface to reduce air flow, at tip, if needed. You can practice on small piece of solder to get melting point and technique down.

20

Yes, the foil your choice but I use regular, is just to divert excess heat. People have wrapped whole video cards in foil but leave NVidia chip expose when baking board in oven to reflow. lol, recipes are online.