6 Jun
2000
6 Jun
'00
6:17 p.m.
Hi Mark,
I would recommend against putting the board in an oven. This will
result in the entire IC getting too hot, and possibly breaking.
Modern plastic package absorb a small amount of water from the air.
Heating the part may result in a small steam explosion. ICs are
shipped from the factory in sealed bags with some desiccant inside.
The label on the outside says to solder them down within a fairly
short time after opening (couple days IIRC).
That being said, you can pick up a small propane torch at most
hardware stores. Any typical propane or MAPP type torch will do. Or you
can use a dremel (or equivalent) to carve enough of the board away
to unsolder one pad at a time (very slow, but the only way to remove
plastic shrouded connectors without destroying them).
Finally, I have access to a hot air desoldering station at work, and
can desolder them for you. Contact me OL for this option.
clint
vaxman(a)uswest.net
On Mon, 5 Jun 2000, Mark wrote:
Hi,
This isn't strictly on-topic, but I guess it could be applied to maintaining
classic stuff, so...
Can anyone recommend a way of removing surface-mounted ICs (specifically SOJ
package DRAM chips) from a board? It's not critical to keep the board
undamaged, but the chips must be kept intact since I want to solder them into
another device.
I read of a technique involving turning the board upside-down and heating the
board area opposite the ICs in question with a blowtorch. The ICs drop off
when the solder melts. I don't have a blowtorch, but do have a gas stove.
Heating the board over the stove will probably not be a good idea, since the
ICs would need to be lifted off when the solder melts. Since I want to
recover several chips, they are likely to get too hot doing it this way.
I do have an electric grill. The element is at the top of the oven. What about
putting the board component side down in the oven (near the heating element),
and heating until the solder melts?
It will be important to get the temperature profile right here, I think.
Putting the board straight into a hot oven might not be a good idea, but on
the other hand having it in the oven as it warms up from cold may be too
long.
In a way, doing this would be similar to IR reflow soldering.
What is a typical melting temperature for solder used on surface-mount
components? The oven control goes up to 260 Celsius (from memory), which I
hope is high enough.
Has anyone else attempted something like this? Do you have any advice?
I guess the same technique could also be used for soldering surface-mount
components (with board component side up, and solder paste applied to the
pads).
-- Mark