Need Help Desoldering
Mar 14, 2009 at 8:07 PM Thread Starter Post #1 of 17
willne1

willne1

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I'm trying to desolder some capacitors on a board. I turned the heat on my Hakko up to 800 deg. and still can't get the solder to melt. what am I doing wrong?
confused_face.gif
 
Mar 14, 2009 at 8:49 PM Post #3 of 17
Do you have a picture of the part on the board?

Either you need to add some solder to make sure you can get a good connection between the iron and the pad, or there's a massive groundplane/heatsink taking away your heat.
 
Mar 14, 2009 at 9:44 PM Post #4 of 17
Thanks guys...flux did the trick. they're hard to get out though. I'm pulling from the top side while melting the solder and wicking on the bottom. I hope I'm doing it right, not as easy as it looks.
 
Mar 14, 2009 at 10:06 PM Post #5 of 17
Nope, it's not always easy. It's highly unpredictable what problems might turn up on an unknown board. I recently had a scare and (wrongly) thought I ruined a board, so I gave in and bought an expensive desoldering station with built-in vacuum. Call me a wimp, but I've had to repair a couple of boards I messed up before. Don't want to do that again.

One thing you definitely don't want to do again is turn up the heat and keep it there if something isn't working. That's a sure way to lift a trace or worse.

If you have to wiggle the cap side to side while moving it out bit by bit, you're better off just lifting it just enough to cut the lead and toss the part.
 
Mar 15, 2009 at 2:09 AM Post #6 of 17
Quote:

Originally Posted by SiBurning /img/forum/go_quote.gif
Nope, it's not always easy. It's highly unpredictable what problems might turn up on an unknown board. I recently had a scare and (wrongly) thought I ruined a board, so I gave in and bought an expensive desoldering station with built-in vacuum. Call me a wimp, but I've had to repair a couple of boards I messed up before. Don't want to do that again.

One thing you definitely don't want to do again is turn up the heat and keep it there if something isn't working. That's a sure way to lift a trace or worse.

If you have to wiggle the cap side to side while moving it out bit by bit, you're better off just lifting it just enough to cut the lead and toss the part.


Hi,
I was looking at MPJA and they have a "Cheap" desoldering station for around $115. Which one did you buy? Did it make a huge difference over a solderpulit? If so, how does it do it so much better/

.
 
Mar 15, 2009 at 5:05 AM Post #7 of 17
I was a solder tech in the Navy - we used Pace PRC-2000s, only way to go in my opinion is to use a solder station with a built in vac, especially with controllable temp. It will pay for itself in time saved and potential damage to pcb/components/wire.

The problem with the PRC-2000 as a civilian is costs close to $5000, so thats out of the question. Ebay has had some decent units, but I'm afraid to go with a brand other than Pace and I can only afford a used unit myself.
 
Mar 15, 2009 at 5:08 AM Post #8 of 17
Quote:

Originally Posted by les_garten /img/forum/go_quote.gif
Hi,
I was looking at MPJA and they have a "Cheap" desoldering station for around $115. Which one did you buy? Did it make a huge difference over a solderpulit? If so, how does it do it so much better/

.


I believe if you ever used a vaccum desolder you would never even think of using any other method, especially for components on pcb.
 
Mar 15, 2009 at 5:22 AM Post #9 of 17
Mar 15, 2009 at 7:15 AM Post #11 of 17
Quote:

Originally Posted by les_garten /img/forum/go_quote.gif
Most likely Junk, but these can be had pretty cheap.

Digital Desolder Station, ZD-915 - [4652] - (Soldering Soldering stations, accessories and rplacement) - Manufacturers: Zhongdi - Komerci - Shop - Electronics and more ...

Zhongdi Manufacture Co.,Ltd.

.


I've run across that one but it seems it had a different manufacturer, i just found this on ebay, this is ideal, great price.

UNUSED PACE PRC2000 PRC 2000 SOLDER, REWORK & REPAIR - eBay (item 150332526671 end time Mar-21-09 23:19:27 PDT)


yeah, flux is your friend
 
Mar 15, 2009 at 12:59 PM Post #12 of 17
Before buying the station, I went hunting online and found a post where someone attached a fish tank pump to one of those radio shack style desoldering irons with a bulb attached. He drilled a hole in the bulb and stuffed the tube into it. I chose not to go that route because I couldn't find an iron I liked enough to do that with. With a bit of ingenuity, and if you don't mind using irons where the tips don't have integrated heating elements, you could put something together on the cheap. I'd be thinking of adding a switch to the air flow, and some kind of filtering (1) close to the tip to trap solder, and (2) beyond that filter to reduce the fumes getting into the pump.

I'm using a hakko 204. It's very nice to quickly suck solder out of holes with one hand. Haven't used it much, but I desoldered an 8-pin DIP without issue. It took two passes because on the first pass I just touched the thing, and you really need to physically move pins away from the side of the hole to suck the solder out of the space where it touches.

[edit]On trying again, the desoldering tool doesn't really work for smd. It's great for through hole. Tweezers work much better for smd. Specialized soldering tips also work well: the soic-8 tunnel and 10mm flat knife are great for soldering or desoldering 8-pin SOIC & DIP. Just got a bunch of new tools, and haven't really got experience with them yet. I just played around with 25mm tips in the 750 hot tweezer to remove a 28 pin smd chip and it works okay, but I wish it would heat a little more evenly--one side seems to get hotter than the other. Same with the 10mm tips. This kind of thing is the main reason I usually skip the cheaper tools.

It's possible to use the 203/4 desoldering handle and tips on a hakko 102 (around $100 on ebay if you're patient). You could attach the heating cord to it and hook up the air side to a cheap pump. Same would go for most other desoldering stations, most of which require separate air. I'm just not sure how well this would work. Most fish tank type pumps are meant to be underwater and pump water, not air.

There's also the hakko 808 that can be had for about $180. There's a lot of recommendations on the internet for this product. I passed on it because I prefer tips with an integrated heating element, but that route's not for the budget conscious. The desoldering tips for the 204 are $50-60. The 808 is a lot cheaper, and people say it works great.

One thing to consider is that technique is by far the most important thing. If you're only desoldering boards you built yourself, you know all the variables, and can get by a lot easier. It's when you start modifying unknown boards that you can get into trouble. The board I thought I messed up recently had some kind of sealant on it, the board material was very flaky, and the traces were embedded below the surface of the rest of the board. None of this was apparent before I started, or at least the consequences weren't. I burned through the sealant, and flaked & burned some of the board material just to get down to the trace. The trace was fine, but it scared me, and brought back memories of boards I actually screwed up in the past. It's a huge pain to fix broken traces, and I mostly work on existing products, not DIY, so I spent the money rather than risk ruining something expensive. I also just bought a used xytronic hot air station, just to play with. One can never have too many toys.
 
Mar 15, 2009 at 1:45 PM Post #13 of 17
Mar 15, 2009 at 2:03 PM Post #14 of 17
Mar 15, 2009 at 2:09 PM Post #15 of 17
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