Re: removing chip from board

[dciotti@pppl.gov (Dave Ciotti)]

In article <rick.light-3004950729530001@slip-dial0610.acc.uwrf.edu>
rick.light@swamp.mn.org (Rick Light) writes:

> I had a couple of RAM chips go bad on a fully loaded Apple 1 meg memory
> card.  I have a number of extra cards with 256 K soldered on the boards
> and would like to remove the chips and use them if possible.  How do you
> do something like this?  Thanks for the help.

VERY CAREFULLY!!!

If you don't know how to do it I would not recommend trying.  Circuit
boards can be easily damaged by desoldering components.

However if you must, get some solder wick from an electronics supply
house.  Using a controlled tip temperature soldering iron gently press
the solder wick onto the solder pads at the base of each lead of the IC
with the iron.  This will eventually suck the solder from the board and
the plated through hole onto the wick.  After doing one pad this way
wait a minuite or so for the board to cool down before starting on the
next hole.  Or you could go to a pin on the other side of the chip if
you don't want to wait.

Then with a pair of pliers try to wiggle the lead in the circuit board
hole.  If the lead wiggles you are done with that lead.  If it does not
wiggle you must suck more solder out with the wick.  Sometimes you have
to apply more solder to the pad to make good thermal contact between
the wick and the circuit board.  Usually if you have to suck the solder
more than two times the pad on the board will lift off the board and
damage the board.

Once all the leads wiggle in the plated through holes the chip can be
lifted out of the hole.  Now you have a $2 memory chip with solder on
the leads.  If you intend to put this chip into a socket the solder
will interfere with the electrical contact between the socket and the
chip.  Make sure the chip leads are clean before inserting into the
socket.

Binary.Bear on GEnie