Chemwick. Not as good on two sided plated through holes but usually works w ell enough.
You mean a desoldering bulb ? Those aren't that good. For plated through, s omething like a Hakko 808 works well. On lead free, you have to turn the he at all the way up. Also, when you see it melt, do not push the vacuum butto n tight away or else you will have an air pocket in there and solder at the top where you cant get a good thermal connection to it.
In any case, if it is lead free the first thing to do is to add some 83/37 to the connection.
Whle it is usually used to remove SMD components, Chip-Quik might be helpful here. Remove as much solder using solder-wik as you can, then apply the Chip-Quik. This with a little heat should allow for easy removal.
I have a Pace machine with a vacuum pump in it, and a hollow soldering tip. It does an amazing job of desoldering parts even from multi-layer boards with heavy copper planes. Generally, after using it, the parts just fall free of the board. The trick is you heat the joint for about 6 seconds, then "swirl" the tip around the hole once, and then keep swirling while you hit the vacuum pedal. The vacuum pump can pump for a lot longer than the plunger-type solder sucker. Usually I take 1-2 full seconds of vacuum while swirling the tip, this gets ALL the solder out of the plated through hole.
When you do this, the swirling of the desoldering tip wiggles the end of the component lead, making sure all the solder in the hole is extracted.
This works about 10 X better than the desoldering suckers, or even the hollow-tip irons that have the vacuum plunger built into the iron.
desoldering stations are great, but expensive... I have one now but I had a soldier sucker before, and managed to desoldier such circuits with quite success. you must first re-soldier the circuit, with fresh leaded soldier then use the soldier sucker, one pin at a time and it will come off (except if it's a multi layer board there you really need a desoldering station)
practice on another board you can destroy if needed. good luck
You have to practise the following on a scrap board , before going for it proper. Retouch solder on each pin, mask off surrounding areas with a "frustrum" made of PTFE slabs, tied together and tied to the pcb. Blast the chip with freezer spray and then blast solder side with hot air gun on full blast, ie as short as possible, while pulling the chip from the other side with bent large circlip pliers, holding the board in a vice while doing all this.
Any air flow (vacuum) after the initial sucking is a waste. The molten solder is sucked away and the continuing air cools the area and... no more molten solder.
The idea is to heat, heat, heat (as much as you determine is safe) and hit the vacuum once. Repeat the whole process if required. If it is required, usually longer heating period or higher heat is necessary.
Yes I?ve found sometimes soldering a joint with fresh solder before de-soldering it makes the process easier. Kind of a mystery why (except if the original is lead-free solder--we all know about that...)
I just started playing with the surface mounted devices about 3 weeks ago after working with the older types for about 50 years. Just glad the old computer boards I have been practicing on must have had the lead solder on them. They seemed easy to work with.
Then I got an old mother board that must have the lead free stuff on it. Using the hot air gun was not difficult to get the old part off. When I tried to clean up the pads the device was on with some solder wick with the old setting of the soldering iron about all I got done was to stick the braid to the pads. Cranked up the heat on the iron and still not much luck. Finally heated the area with the hot air gun then used the braid and iron and that worked much beter.
Any other good hints on workig with the lead free solder other than preheating the board ? Even putting some tin/lead solder on the pads don't seem to help.
The vacuum has to last long enough to remove ALL the solder in one go. If it doesn't, the tiny remaining bits of solder don't conduct heat to the far end of the pin. With the hollow copper desoldering tip on the joint, it does NOT cool off, in the second or two it takes to pull all the solder out.
I wish you could see this Pace unit work, it is totally amazing! I fairly routinely desolder some 68-pin connectors, and they just fall off the board when you are done.
You have to overload each PbF joint with PbSn solder, the result is not supposed to be pretty or pass QC, doubling the blob size at least, to have good effect at reducing the required tempearature to desolder them
Yeah but on plated through holes that might result in a bog blob on the top of the board, which will be harder to heat up and suck out. You really need to heat the shit out of it to mix ALL the solder. And that is what creates this risk.
Agreed. I have and use an old Pace: Note the gas brazing tip cleaning tool. You'll need it. There's a glass tube inside the handle which also needs to be cleaned. The vacuum inline filter also tends to get clogged every few years and will need to be replaced. However, an automobile fuel pump filter also works.
Pace desoldering stuff on eBay:
Yeah, that works but I do it a bit differently. I "swirl" the tip around to get the last bits of solder, but I don't try to clean the hole at this point. Once the part is removed, I either make another pass with the vacuum pump, or I clean up the mess with an ordinary soldering iron and a mechanical solder sucker. The problem is that if I use too much vacuum, the solder gets cold, turns to dross, and is then difficult to reflow or remove.
I have several soldering irons with hollow tips and either a bulb or mechanical vacuum solder sucker attached. They were a waste of time and money. The Pace vacuum desoldering station works the best.
Jeff Liebermann email@example.com
150 Felker St #D http://www.LearnByDestroying.com
Go ahead and cut the pins, but as close to the board as possible. Then solder the "amputee" to a 28-pin header. You stand a far smaller chance of damaging it that way, than if you try to get all the legs out at once. Also much less chance of ripping the plating out of any of the holes.
The type of soldering iron with a rubber bulb solder sucker attachment can work well, but if you take care to avoid damage from the recoil, a piston type solder sucker can also work.
add flux and make sure all the solder is liquid before activating the sucker.
If at first you don't succeed - remake the joint with fresh cored 60/40 solder and try again.
As long as you can shift about 90% of the solder out of the hole; you can wiggle each pin free with small pointy nose pliers. Sometimes the chip will almost fall out, but an overlooked sliver of solder can rip a via out as you pry the chip.
Before levering the chip; grip the chip body and flex it in each direction, this will contribute to freeing stuck pins and also show up the ones that need another visit from the solder sucker.
firstname.lastname@example.org wrote in news: email@example.com:
+1. Chip-Quik will get the melting point of the remaining solder down to around 100 deg C so you can keep all 28 joints molten with a hot air gun on a fairly low temperature setting without cooking the board.
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)