[Open-graphics] Designing a DDC injection box

[Peter TB Brett]

On Friday 01 September 2006 17:55, Dieter wrote:

> For the most part I agree.  De-soldering a DIP from a board without
> destroying it is the exception.  The legs love to stick to the walls of the
> hole, even with the use of solder-suckers and solder-wick.  And even
> high-quality boards with experienced rework people are only good for about
> 5 replacements. With a low quality board you're lucky to replace a chip
> once without destroying the lands.  So I never solder DIPs to a board, I
> always use sockets. 

True: trying to replace a DIP by the 'traditional' technique (desoldering each 
pin with a sucker and then pulling the chip off) almost always destroys the 
PCB.

However, replacing a DIP is actually quite easy, if you don't want to reuse 
the original DIP.

1) Clamp the board (in a vice, usually) so the package body is downwards and 
the pins upwards

2) Get a *high power* soldering iron and flood all the pins of the package 
with a giant blob of solder.  Stroke the iron backwards and forwards, keeping 
all the pins nice and hot.

3) The DIP will fall out under its own weight, lubricated by the molten 
solder.  Throw it out, it'll almost certainly be wrecked.

4) Get some braid and a flux pen and carefully clean the footprint.

However, this is impossible (or at least very tricky) to do for packages with 
more than 16 pins, unless you're quite experienced at this technique.

If someone who *doesn't* have a lot of rework experience is going to be 
expected to need to replace the chip, fit a DIP socket. ;)

Peter

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