Lately I had to make a few … “revisions” … to one of my PCBs that required desoldering a number of components. This is very easy when using SMD devices either with hot air or solder wick. However, I’m having a devil of a time doing it with through hole components. It was one thing when I used to work with single-sided boards without plated through holes, but these double-sided boards with plated through holes are much more difficult.
I tried using solder wick, which cleans up the pad nicely, quickly removing all visible solder from both sides in one shot. However, there’s always just enough solder left in the plated hole to stick each pin of the component. The usual result is one hand fighting to pry the component off with a lever or a pliers while the other hand quickly tries to heat the pins. I had to remove some TO-220 devices which were a bit tight in the plated holes to start with, and one of them stubbornly ripped off the pads and the plated through hole with it.
So, my question is… Is there any helpful technique or tools? I’m using high-quality desoldering wick that has served me well everywhere else. I have a SMD hot air rework station available, although I did not try it (I’m thinking maybe next time use hot air to try to heat the whole component).
Do the vacuum-operated desoldering stations work better than desoldering wick? In particular, I’ve considered upgrading my aging Xytronic iron with something like this: http://www.howardelectronics.com/xytronic/lf8800.html, but don’t want to spend the extra money for a desoldering station if it’s no better than desoldering wick.
Depending on the part, if you use enough solder, you can get all the pins molten at the same time. Then just pull out the part. I’ve done this with 2x8 0.1" headers many times. Should definitely with with your TO-220s too.
For bonus points, if you expect to be “revising” anything with through hole stuff, sockets are your friend (especially for DIP-anythings).
I feel your pain… After wicking the pad it is possible to cleanly remove the part. The key is where you put the heat and for how long. Use some tweezers and hold the pin which will act as heat sink. Now you want to focus your heat on the pad and only the pad. This will hopefully heat up the solder enough and keep the pin cool that you can ‘break’ the bond. As you remove the iron from the pad move the pin with the tweezers as everything cools. With practice you can nicely remove the part, I will warn you though its not very easy.
edit: I missed the fact you have a hot air rework station. I would just use that.
rrpilot:
edit: I missed the fact you have a hot air rework station. I would just use that.
I second that. If I have to remove a throughhole part with more than 2 or 3 pins I use hot air.
As for the situation where the pins are a tight fit to begin with, that’s always going to be likely to damage the pads when you try to desolder. Assuming you don’t need the part anymore, try cutting off the leads and desoldering the pins one-by-one.
Chipquik is your friend. First, remove as much solder as possible with wick. Next, add a tacky flux to each pin, and then add chipquik to each pin and heat up each pin for a good 3 seconds or so. Once you’ve done all pins, go through and heat each up quickly for half a second, and remove the component.
Way way way less dangerous than hot air. Hot air, if you aren’t careful (and don’t preheat), can cause your PCB to heat up incredibly unevenly and delaminate.
Chipquik is a bit spendy - but it is well worth it. Practice on a dead board first though so that you get the hang of using it. It’s fairly easy - but you still want to practice first.
While repairing some of the retro computers I have, I tend to use hot air to remove components - first I use wick to remove as much solder as possible, then heat the board from below - I remove all sorts of ICs this way (I always put a socket in when I’m done, though). I do the same to salvage useful parts from scrap boards, and the parts I’ve salvaged have all worked. You do need to be careful with hot air though not to damage the PCB, but with practise it’s fast and easy and gives good results.
I like desoldering pumps a.k.a. solder suckers. They are inexpensive and quick to use. Simply cock the desoldering pump, line it up with the pin that needs desoldering, heat the pin with your iron, and pull the trigger when it’s molten.
For through-hole components, I like to use the wiggle method.
First, remove as much of the solder as reasonably possible using whatever method. Then, heat the lead with a soldering iron, wiggle the lead with a tweezer, remove the iron, and keep on wiggling until the solder solidifies.
Repeat for all leads, and the component should pull out easily.
I’ve tried wicking and solder pumps, but had very little success. So I bought one of those blue Chinese 220V vacuum de-solder guns on ebay for $30. I use it with a $5 50Hz/220 plug converter and it works like a champ. I have since purchased an expensive Aoyue desolder station and have found that the blue gun works just as well.
