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Topic: Removing DIP chip? (Read 4732 times) previous topic - next topic

amacmullen14

Apr 05, 2010, 02:27 am Last Edit: Apr 05, 2010, 02:27 am by amacmullen14 Reason: 1
Noobish question:

I have a 18 pin dip ic soldered into a protoboard.
What's the easiest way to remove it with only a soldering iron and other general stuff?  I tried a solder sucker, but it couldn't remove all of the solder.

RanTalbott

If you get almost all of the solder out,  you may be able to break individual pins loose with some careful wiggling.  A pair of 4.5" bent needle-nose pliers are great for this:  they make it easier to grasp single pins without needing to be a contortionist.  The wiggling trick only works if you've gotten out enough solder that you can see,  by shining a light through the hole,  that it's almost completely cleared.  You need to grab the pin so the tips of the pliers are flush with the solder side of the board,  and gently move it so the last little bit of solder breaks.

When you're down to the last couple or three pins,  you can start working the chip out by prying from underneath with a small screwdriver while heating the stubborn pins.

retrolefty

Also solderwick can be useful.

Lefty

amacmullen14

Thanks I'll keep trying.

westfw

Are you trying to preserve the chip, or the board, or both?  Removal techniques differ...

amacmullen14

Yeah, I kinda want to preserve the chip even though I think it may be faulty.
The protoboard I want to definitely preserve.

brtech

This technique works best after some practice, but it works:

Use solderwick to get most of the solder off.  This is essential.  Radioshack has solderwick.  Don't try removing without it.

Use a small screwdriver under ONE END of the dip
apply heat with the iron, carefully, starting at the end with the screwdriver, heat, lever, heat, lever.  You often have to heat 2-3 pins to on one side get anything to move. Then do the other side, then back to the first, ...  You aren't using the lever to break any solder connections, you do that with the iron. The chip moves in very small increments at first.

The pins on the chip will bend, but after you get it out, you can straighten them.

When you replace the part, solder both the top and the bottom of the board.


MarkT

Solder suckers are much quicker than wick, but you have to make good contact (square on to the board) to suck all the solder - and you have to do this while the solder is still molten - which means being quick to replace soldering iron with the sucker nozzle...

There are also special soldering bits that heat all the pins in a DIL package at once, so that you can pull it all out in one go - however this is a rather expensive solution for one chip.  For an electronics repair shop it's clearly useful!
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

tjmck

The chip is likely damaged due to the heat you have already applied.  The best way to preserve the protoboard is to cut the pins at the body of the chip.  Once they are all cut and the chip body is removed, you can easly remove the pins one at a time using minimal heat.  Go back to the empty holes with a piece of solder wick.  They will come clean easily.  (This was the method military electronics manufacturers were using in the dark days of the 1970's to rework assemblies with little risk of damaging the circuit card.)

tjmck

KenH

and once the holes are all cleaned - install a socket!!! makes removing the DIP chip a lot less hassle....  UNLESS the circuit is so critical the extra cap/inductance from the socket will mess up the circuit.

Ken H>

amacmullen14

Cap or inductance doesn't matter-- there's not enough room to place a socket.  Directly above is an led matrix in female headers.

Grumpy_Mike

#11
Apr 06, 2010, 02:56 pm Last Edit: Apr 06, 2010, 05:29 pm by Grumpy_Mike Reason: 1
Quote
there's not enough room to place a socket.


If there is enough room for an IC then there is enough room for a socket. I have some sockets that consist of just a strip of metal sockets connected by a metal tab. Once you have soldered it in you bend the tab over and break it, leaving you with a socket that has no housing and therefore will not require any room.


Have you seen this page:-
http://tuukan.fliput.net/pcbfix_en.html
It doesn't use the socket strip I talked about but it is good at showing the principals of what to do.

MarkT

Quote
Cap or inductance doesn't matter-- there's not enough room to place a socket.  Directly above is an led matrix in female headers.


You can always mount the socket on the other side of the board and bend the IC pins backwards before plugging it it.  This is definitely a kludge though!
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

amacmullen14

Thanks for the advice about sockets, etc, bu first I have to actually  get the chip out, I haven't had free time.

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