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Norm
Joined: 17 Aug 2007
Posts: 6
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 27 May 2008 8:35 How can I desolder a DIP28 package? |
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Hello,
I've been trying to find a suitable desoldering solution to repair my boards with faulty 28-pin DIP multiplexers on them.
I've searched quite a bit and only found Leister's contactless desoldering stations which are extremely expensive.
I've been told that Weller and Ersa have products that have interchangeable tips for DIP sockets. They are high power soldering stations presumably, and when you change the standard soldering tip with a 28 piece one, the increased power enables you to heat all the pins of the IC at once and take it away with a tweezer.
I have found neither of the brands' products that match this description. Not only there is almost no reference to available tips, most of their soldering stations are 60W.
If anyone has any experience or know of a way to desolder a 28-pin DIP package, please let me know. If I can choose, I would prefer Ersa tips because I have Xytronic soldering station and Ersa tips might be compatible with it.
thanks
norm
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FvM
Joined: 22 Jan 2008
Posts: 2632
Helped: 431
Location: Bochum, Germany
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| 27 May 2008 9:19 Re: How can I desolder a DIP28 package? |
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If I have access to, I'm using a good vacuum desolder tool, e. g. Weller. I sometimes replaced Z80 processors this way. If the component has very tight drill diameter at it's pads, it may be easier to cut the pins and desolder them individually with tweezers.
The said Ersa desolder tips are still available up to DIL16, I'm not sure if larger variants have been manufactured previously. By the way, a toolmaker should be able to make a custom desolder tip, brass would be a compromise that gives some (limited) lifetime without a galvanized steel surface.
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cyberrat
Joined: 19 Jun 2001
Posts: 898
Helped: 31
Location: In the sewers of the U.K.
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| 27 May 2008 9:29 How can I desolder a DIP28 package? |
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There are high power soldering irons with bits that will cover allpins, but they are rubbish.
If the device is faulty then you are better doing as FvM sugests & cutting pins & desoldering individually.
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Norm
Joined: 17 Aug 2007
Posts: 6
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| 27 May 2008 9:51 How can I desolder a DIP28 package? |
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Thanks for the replies
If you have any part numbers you can point me to, it would greatly aid in my research. We will try to build a custom soldering tip for the DIP28 package, but I'm not sure if the poewr output of our soldering station would support it.
We would buy a new soldering station if need be, but we have no product numbers to go by, so we are lost in the redundant universe of brand catalogs.
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banjo
Joined: 24 Dec 2005
Posts: 473
Helped: 89
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| 28 May 2008 14:29 How can I desolder a DIP28 package? |
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I have removed lots of similar chips using just solder wick. This has always worked. Perhaps you might have difficulty if the drill is too small or there are multiple internal PCB layers.
If solder wick does not work, I would suggest getting a hot air rework station. You can use the pencil tip nozzle to wave across the pins and heat them all.
If you have lots of boards to do, another solution is to get a solder pot. These have a little pool of melted solder. You have to make a mask to shield the area that you don't want unsoldered. The you dip the bottom of the board at the DIP28 chip in the melted solder pool and pull the chip from the top.
The good thing about either hot air or the solder pot is that you are not limited to only one size component.
Regardless of the removal method used, you will still need either solder wick or a vacuum desoldering tool to remove the solder from the holes before installing the new chip.
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echo47
Joined: 07 Apr 2002
Posts: 4206
Helped: 565
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| 28 May 2008 14:57 How can I desolder a DIP28 package? |
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Pins attached to power planes can be stubborn to unsolder. I prefer to cut all the pins, remove the body, and desolder the pins individually. The technique also works for smaller parts such as TSSOP ICs. My favorite cutters are the Lindstrom Rx series, such as the Rx8147. They are expensive (about $60 US) but worth it. Don't drop them or cut heavy stuff.
http://www.lindstromtools.com/tools_cutters_rx_assort.htm
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banjo
Joined: 24 Dec 2005
Posts: 473
Helped: 89
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| 29 May 2008 13:43 How can I desolder a DIP28 package? |
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For cutting DIP pins on crowded boards, I often use an X-Acto knife with a very pointy triangular blade. Stick the point of the knife between pins 1 and 2 with the sharp edge on pin 1. Then using pin 2 as a fulcrum point lever the knife to slice through pin 1 at the point where it enters the body. Repeat the process of all other pins on that side. The final pin on each side you have to cut with snips as no fulcrum is available.
This method will chew up your X-Acto blade after a couple of ICs, but these are very cheap.
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jacklim
Joined: 03 Apr 2007
Posts: 11
Helped: 2
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| 02 Jun 2008 13:13 Re: How can I desolder a DIP28 package? |
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Use a desoldering tool to remove solder in every pin hole until you can see through to the other side.
In this state use a flat blade screwdriver to alternately prise each end of the IC off the board. The force applied is enough to shear off the small amounts of solder still sticking any pin to the PCB.
If cutting of pins is needed use a mini cutter plier with jaws slim and pointed enough to cut each pin easily.
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