Advice on Desoldering an IC

[Rob Jarratt]

I decided to invest in a Hakko FR-301. It worked almost immediately. Hours of trying before, I did it in 10 minutes!

Regards

Rob

> -----Original Message-----
> From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of dwight via cctalk
> Sent: 16 April 2022 14:00
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Subject: Re: Advice on Desoldering an IC
> 
> Sometimes the IC has been installed with the pins under tension. This is
> typical of machine inserted ICs. When the solder is loose, bend the pin away
> from the side it is pressed against. Do this carefully, don't over bend. You
> want it to center in the hole. I recommend doing this with a separate iron
> than the desoldering tool, so you can see what you are doing. Once the pin is
> nicely centered in the hole use the desoldering tool to suck the solder out.
> Make sure to always use a clean tip. An oxidixed tip will require excess
> pressure to transfer heatand damage the trace. Keep the solder shinny with
> a spung or soft metal wool. Do mot use a hard metal to clean an iron clad tip
> or it will damage the iron and rot it from the inside 🙁
> When not using the iron but leaving it hot, always leave a blob of solder so
> that it won't have a thin oxide coating that is hard to remove. KEEP A CLEAN
> TIP!
> After sucking the solder with the tool, with a small screw driver, give the pin a
> slight sideways pressure and let the screw driver slip off the pin. It should
> make a plink sound or a momentary ring. This is something that you'll just
> have to learn the sound of. If it doesn't sound right it means it isn't free of
> the sides. Add solder and try to bend the pin.
> Often the body side of the IC will have a tiny film of solder right where the IC
> sits on the trace. If this is just the tiny amount to solder, one can break it
> loose with a pair of short needle nose pliers, By squeezing the two sides of
> the IC together. Don't expect to break loose a large blob.
> Of course, if you expect to throw the IC away, use sharp pointed dikes to cut
> the pins at the package and pull each pin individually while the solder is hot.
> Use a small vice to hold the board so you can work from both sides. Tweezers
> are best but heat the solder first and when hot grab the pin from the top.
> Work quickly while the solder is hot.
> You may need to refill the pin with fresh clean solder. Old oxidized solder
> does not remove easily. Use separate rosin flux if you have it ( not plumber
> flux!! ).
> Like I said earlier, use a really clean tip. It should be shinny before trying to
> heat the board. It is hard to do with the higher temperature solders. There is
> some low temperature stuff you can use to remove solder more quickly.
> I like using a large manual plastic solderpulit. Some like to use solder wick.
> The solder removal suckers are often hard to keep the tip clean. If you have
> to press hard on the tip to the work, the tip is not clean. It does help to have
> some really tiny flux core solder to touch right at the junction of the iron and
> work to start the heat transfer. Never use force to get the heat to start to
> transfer! Clean tip and a quick touch with solder is all that is needed.
> When you are not using the iron for some time, but leaving it on, add a
> thicker blob of solder on it so it doesn't get a thin hard to clean oxide on it.
> KEEP YOUR TIP FREE OF THIN OXIDE!
> Dwight
> 
> 
> 
> ________________________________
> From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Rob Jarratt via
> cctalk <cctalk at classiccmp.org>
> Sent: Friday, April 15, 2022 10:49 AM
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Subject: Advice on Desoldering an IC
> 
> I am trying to remove an IC from my PDP 11/24 CPU, a DS8641. I am really
> struggling to desolder it. I am using the technique of applying fresh solder
> and then removing it. But after multiple cycles of this I think I am starting to
> damage the PCB.
> 
> 
> 
> I am using a fairly cheap desoldering station (this one
> https://cpc.farnell.com/duratool/d00672/desoldering-station-uk-eu-
> plug/dp/SD
> 01384?st=duratool%20desoldering). Its spec in terms of vacuum pressure is
> equivalent to that of the professional Hakko ones though. I am also trying a
> hand desoldering pump. None of these are able to clear many of the holes of
> solder, although some are doing better than others. Nevertheless, the IC
> remains stubbornly unmoving.
> 
> 
> 
> Are there any tips for removing ICs?
> 
> 
> 
> Thanks
> 
> 
> 
> Rob