Removing surface-mounted ICs

From: jpero_at_cgocable.net <(jpero_at_cgocable.net)>
Date: Sun Jun 4 17:21:40 2000

> From: Mark <mark_k_at_iname.com>
> To: classiccmp <classiccmp_at_classiccmp.org>
> Date: Mon, 05 Jun 2000 00:58:27 +0000
> Subject: Removing surface-mounted ICs
> Reply-to: classiccmp_at_classiccmp.org

> Hi,
>
> 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?

Get a old heavy alumium baking pan and start cooking on electric or
gas. Heat on high starting with piece of solder wire dabbling
the pan till solder melts and balls up then turn low bit towards
medium. Wait for few minutes, then tap the chips you want to take
till it is free and pick them up with tweezers or needle long nose
pliers. I often find the melting point of solder is hot enough even
on low on any stoves.

Warning: It will smell if heat is too high.

For those dual SOJ or gull wing (not the quad SOJ/gullwing kind), I
take two 40W solder irons (grounded) and melt excessive solder acts
as heat capacity to keep solder molten and keep moving both solder
together. Till chip is loose then pinch the chip with the solder
iron tips quickly lift up and let it drop on the metal or cardboard.

Clean leads up with fresh blob of solder dragged across them by
holding the chip vertical using gravity and surface torison do the
work. I do that same for installing all SOJ and gull wing pitch of
.025 by tacking two leads down to hold it in place and solder
excessively then drag the blob, solder will want to leave the leads
and try to run off at the last pin but you can prevent it when
moving the solder tip carefully.

> 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.

All cooking of any types are hot enough, over 500F on high without
water load. Heated metals that are glowing red and orange ia over
1000F and bit more. Because of this glow the water has very high
specific heat capacity and that takes so much heat to bring it to
boil quickly and keep it there.

Oh yes can melt cheap aluminum spun thin pots with a stove. I
had this happen few times. Without warning too.

Look at burned buses and airplaces, aluminum melted because fire is
hot enough.

> -- Mark

Wizard
Received on Sun Jun 04 2000 - 17:21:40 BST