Big desoldering tool for SMT transformers? - Page 1
Forum section: electronics / general

author: jrs45
author_rank: Regular Contributor
timestamp: February 17, 2022, 08:03:34 pm
content: We have to harvest a bunch of SMT transformers from old boards to get us by for a while. These are 12-pin transformers, about 2x2cm, so a regular iron isn't going to cut it.Maybe a beefy preheater placed right under it would get the board hot enough to melt the solder? Or combined with hot-air?Any recommendations welcome!

author: coppercone2
author_rank: Super Contributor
timestamp: February 17, 2022, 08:31:52 pm
content: pictures would help alot, it sounds like a job for a pace soldering tweezer attachment

author: thm_w
author_rank: Super Contributor
timestamp: February 18, 2022, 12:09:48 am
content: Yeah you can preheat to the point of melting the solder, if you don't mind the wait and don't care about any components on the bottom of the board.Make sure you have good ventilation.Another option might be the really wide tips:https://hken.rs-online.com/web/p/soldering-iron-tips/5175575But you need a reasonably high power iron.Quote from: coppercone2 on February 17, 2022, 08:31:52 pmBiggest is 28mm so could work:https://www.waveroomplus.com/Pace-1124-1010-P1-SMT-Mini-Tweezers-Tips-Chip-03-x-109-7-x-28mm_p_1618.html

author: coppercone2
author_rank: Super Contributor
timestamp: February 18, 2022, 12:25:08 am
content: You can also get copper wire/rod that fits into your soldering iron and bend it into the correct shape to make a ghetto pace like extraction tool, possibly filing the wire after its bent for the right form factor. Just keep in mind it will contaminate with copper and have a short shelf life and it will be hard on your soldering iron.. however unless you are running a pro repair shop it might be useful.

author: jrs45
author_rank: Regular Contributor
timestamp: February 18, 2022, 01:56:23 pm
content: Thanks! Here's a photo.Each set of terminals is just over 2cm (2.2cm). I did try a preheater but it's too slow.Looks like wide irons is the way to go? The Pace MT-100 tweezers with the special tips look promising, but I'm not sure if the tweezers can span such a large part.It might be safer to just get a couple of big irons with wide blade tips. The Hakko one posted is discontinued, sadly. Maybe something like a pair of T12-1404. I'll have to dig around I guess.

author: Shock
author_rank: Super Contributor
timestamp: February 18, 2022, 02:58:11 pm
content: Solder low melt alloy (chip quik) to the pins while underside preheating and hot air if needed to lift.If you have some copper stock you can diy blade tips. Drill a hole in two blocks and use two cheap irons that use solid core tips. Cut the excess tip off bang it into hole in the block. Put it back on the iron and apply lots of solder to the downside edge. Use preheating and some flux on the board.The height also might prevent tweezer blades, on the old Pace TT65 tweezers you could just flip them around and bend them to suit or drill a hole and bolt on some copper cut to shape (modify them while removed from the tweezers of course).

author: thm_w
author_rank: Super Contributor
timestamp: February 18, 2022, 11:48:18 pm
content: Quote from: jrs45 on February 18, 2022, 01:56:23 pmAll of the "T12" stuff is technically discontinued. They've just changed it to "T15". So if you see a T12 tip for sale on line its mostly clones.If you want ultra low budget: two T12-1404 clone tips and two KSGER stations.If you have Hakko stations already, and higher budget, official T15 tips:https://www.digikey.ca/en/products/detail/american-hakko-products-inc/T15-1403/6228866If you have other stations, then check what they offer.I assume you are willing to break off those capacitors on the left hand side to get the large tip in there.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 19, 2022, 12:07:17 am
content: Assuming you can destroy the boards, one approach is to use a soft propane flame on the back side. I have unsoldered RF components and their fully soldered shields that way. You can also snip and saw/drill the board so the smaller pieces can be removed.

author: jonpaul
author_rank: Super Contributor
timestamp: February 19, 2022, 01:38:27 am
content: Metcal irons large blunt tip.Or cheap Chinese vacuum pump irons, $13Jon

author: bdunham7
author_rank: Super Contributor
timestamp: February 19, 2022, 02:11:39 am
content: You might consider taking a large QFP hot air nozzle, cutting off and sealing two of the four nozzle sides and using that with a preheater. If you got the right size nozzle, you could easily melt the solder without significantly heating the transformer and the missing sides of the nozzle would give you space to grab the transformer with a customized pliers of some sort.https://www.techni-tool.com/product/821TI126-A1126B?gclid=Cj0KCQiApL2QBhC8ARIsAGMm-KG9cz--YjKL049qTy66Ynq6N6ZDoC7HdIp12OS9bPG65-jrODtvtckaArQEEALw_wcB

author: jrs45
author_rank: Regular Contributor
timestamp: March 11, 2022, 07:21:21 pm
content: For anyone stumbling upon this thread, and wondering what the solution was, a big wide tip like this worked beautifully:https://www.tequipment.net/Pace/1130-0502-P1/Tips/Flux helped, of course, as it always does.

author: Shock
author_rank: Super Contributor
timestamp: March 11, 2022, 07:51:16 pm
content: Did you use two irons or just go side to side? Yeah flux and preloading the tip with a little solder helps, you get a quicker thermal bridge that way so it dumps heat through the legs more efficiently.

author: jrs45
author_rank: Regular Contributor
timestamp: March 12, 2022, 11:53:48 pm
content: Just one side at a time, worked well enough and saved me the $$ from buying another iron. Just lifted the side slightly, moved to the other one.