Cutter for cutting DIP pins - Page 1
Forum section: electronics / general

author: ezalys
author_rank: Frequent Contributor
timestamp: January 19, 2019, 10:07:57 pm
content: When desoldering cheap DIPs from a particularly delicate and expensive board I prefer to cut all the pins and pull the pins out one by one with an iron and tweezers. The problem is getting the cutter between the pins. Does anyone have a favorite pair of cutters for getting between dip pins that can deal with cutting sideways through the flat copper part close to the package? I want to be able to go in from above, with the pliers pointing normal to the board. Erem, lindstrom, excelta or similar quality prefered.

author: jfiresto
author_rank: Frequent Contributor
timestamp: January 19, 2019, 10:49:14 pm
content: How about an end cutters likethis one? It will be too light for plated steel pins [make that iron-nickel -- see later correction], but you say you will be cutting copper?Tomorrow, I can check if it, and a sibling with a more angled face, will slip around a DIP pin. (It is getting late here.)

author: james_s
author_rank: Super Contributor
timestamp: January 19, 2019, 11:04:04 pm
content: I never understood why people cut the pins off, especially now. With a decent desoldering tool there's no need, you can pop a DIP out in a minute or two, test it out of circuit and reinstall the same part if it tests good. It takes longer to cut the pins off and desolder them one at a time and you can't reuse the chip if it turns out to be good.

author: sotos
author_rank: Frequent Contributor
timestamp: January 19, 2019, 11:12:34 pm
content: Here you are, pick one you like.https://www.weidinger.eu/en/shop/tools/side_cutters_and_other_cutters/erem_side_cutters/erem_special_cutting_pliers_esd/wl27277https://uk.farnell.com/erem/670ep/cutter-tip-smd-110mm/dp/7256450https://www.amazon.com/schmitz-3563HS22-without-Hightech-professionals/dp/B00CMR066Mhttp://www.engineer.jp/en/products/nz10_13e.htmlhttps://catalogue.facom.com/dk-en/categorie/electronics/electronic-pliers-antistatic-series/cutting-pliers-for-dip-cms-components/produit/esd-diagonal-cutters-for-dip-cms-components/417-spehttps://smtsupplies.com/CHP_Cutter_I.C._Pin_Cut_16g_Dissipative

author: ezalys
author_rank: Frequent Contributor
timestamp: January 19, 2019, 11:55:14 pm
content: I have a pretty good desoldering tool (Hakko FR-300). I just can't always get all the solder out from around the pin. Maybe my technique is bad. There's always one or two pins that I can't get the solder out from around. When I keep trying, I might end up inflicting a little damage to the board. Clipping the pins, especially for something like a cheap jellybean opamp, seems much safer.

author: ezalys
author_rank: Frequent Contributor
timestamp: January 20, 2019, 12:43:59 am
content: Also, I'm afraid I had no idea that the lead-frames are made of steel! I suppose I want something that'll handle that then.

author: james_s
author_rank: Super Contributor
timestamp: January 20, 2019, 03:54:25 am
content: Keep the desoldering gun clean so it is operating at peak efficiency. Suck the solder out and then orbit the tip a few circles to get the pin separated from the side of the hole. If it doesn't work, add fresh solder to the pin and try again. As a last resort you can snip the pins but it's very rare that I have to do that. Only when I'm absolutely positive the IC is bad and the board is particularly tricky.

author: cdev
author_rank: Super Contributor
timestamp: January 20, 2019, 05:39:08 am
content: Heat up the board from below with a hot plate to around 100 degrees C and then apply the hot air from above and you should be able to lift it up and away much faster than without the heat without keeping the circuitry too hot for too long.

author: jfiresto
author_rank: Frequent Contributor
timestamp: January 20, 2019, 11:28:03 am
content: Quote from: ezalys on January 20, 2019, 12:43:59 amSorry, my mistake! Iron-nickel, in particular Alloy 42 (Fe58Ni42) and Kovar (Fe54Ni29Co17), has long been a popular lead-frame core material. You may encounter that, rather than copper, especially on older parts.

author: macboy
author_rank: Super Contributor
timestamp: January 21, 2019, 06:39:51 pm
content: Quote from: ezalys on January 19, 2019, 11:55:14 pmYou should never damage the board with the desoldering tool because its tip should never even touch the board!A heated tip vacuum desoldering tool like your Hakko is effective and safe when used correctly. I always make sure there is a good amount of solder on the pin(s) being desoldered. This may mean adding a little leaded solder. If I know the joint is lead-free, I always add leaded solder (I have no need to maintain the lead-free status of my purely hobby level work). Bring the tipstraightdown over the component pin. When it starts to melt, wiggle the tip back and forth (for ICs, transistors, things with rectangular leads) or in a circle (passives with round leads), but keep the tipjustabove the pad when doing this. Don't rub the tip against the pad. For 2+layer boards, you will feel a difference when the solder is finally melted all the way to the other side - the pin will wiggle more easily. Itmustmelt all the way through; Verify visually if needed.While still wiggling, activate the vacuum, andkeep the vaccum onwhile pulling the tip back from the pin until it is free. The motion plus the cooling action of the air rushing in should prevent the pin from sticking to the hole plating. Note that the tip is never pressed into the board. That not only damages the delicate pads, but it actually transferstoo muchheat directly to the board, so that the solder remnants in the hole may remain molten for too long, causing the pin to stick to the hole plating. When you perfect this, you will have 40 pin DIPs falling off the board on the first pass.To help avoid too much heat on the component/board, do every third pin. Then go back and do a second pass, and then a final pass to get them all. This spreads the heat load. If the pin isn't freed and you need to rework it, always re-solder; you need a continuous blob of solder from bottom to top. To avoid overheating, wait little while (desolder a few other pins) then go back, re-solder that pin, wait a while again, then finally go back and desolder.That's how I do it, and it works great for me, but I'm not an expert and I'm always open to suggestions. The detail of keeping the vacuum on while removing the desoldering tip from the board was an "Aha!" moment for me. I forget where I learned that, but I'm sure it was on this forum. Hopefully this helps you or others.

author: ezalys
author_rank: Frequent Contributor
timestamp: January 21, 2019, 07:37:40 pm
content: Thank you so much! I'll give this a try.

author: Cnoob
author_rank: Regular Contributor
timestamp: January 23, 2019, 08:00:29 pm
content: All the IC pins/legs I have cut have been plated copper.https://en.wikipedia.org/wiki/Lead_frameI have done this since 1980.If you need to protect the pcb I would sacrifice the IC unless it was expensive.Another pair of cutters are lindstrom series 80 modle 8211 cutting capacity 0.2mm to 1mm copper wire.

author: sotos
author_rank: Frequent Contributor
timestamp: January 23, 2019, 08:28:52 pm
content: Also here, 30 years pcb repair. What I do? I cut all the legs, take them off one by one and then desolder the holes with me Pace desoldering hanpiece.Expensive chips, a heat the pin from the component side with my soldering iron while at the same time a desolder the pin from beneath, solder side.They come off easily without destroying something.

author: jfiresto
author_rank: Frequent Contributor
timestamp: January 23, 2019, 08:53:14 pm
content: Quote from: Cnoob on January 23, 2019, 08:00:29 pmI just ran a magnet over a mix of ca. 120 SSI/MSI/LSI integrated circuits on two boards, one from the late 1970s and the other from 1985. Two thirds of the ICs were magnetic.

author: Cnoob
author_rank: Regular Contributor
timestamp: January 24, 2019, 05:03:23 am
content: component leads are nickel plated and nickel is classed as ferromagnetic along with iron, cobalt and gadolinium.Edit some component leads are.

author: jfiresto
author_rank: Frequent Contributor
timestamp: January 24, 2019, 09:30:21 am
content: The following excerpt is consistent with what I found during a half hour or so of web-snooping. It does not mention Kovar, a "typical" lead frame material for at least one IC lead frame manufacturer.QuoteFrom"Info Tracks", issue 53, November 2013, Semitracks Inc.

author: Cnoob
author_rank: Regular Contributor
timestamp: January 24, 2019, 04:46:18 pm
content: That must be the same alloy they used in Valve/tube pins, as I said I have never come across it on semiconductors.

author: all_repair
author_rank: Frequent Contributor
timestamp: January 24, 2019, 04:52:36 pm
content: If you cut off the pins and desolder one by one is the best approach. A toe nail cutter is well suited for this task. IC legs are quite soft, connector pins may not be so suitable if they are too hard.