On Thursday, April 12, 2018 at 1:17:00 PM UTC-4, Jeff Liebermann wrote:


You get sort of a feel for how big of a daub or bead to apply.
Ideally it should stick slightly out the sides of the device,
that assures full coverage. You don't want a huge amount of
excess. Also in some cases it is a good idea to push the device
on to the heatsink by hand with as much force as possible.
Screws strip in aluminum and some of them have a spring type
hold down.

Sigh.

Not sure where you disagree Jeff. Not speaking for the other Jeff (jurb), but I agree with him. If you get too much compound out of the sides, you've wasted it. If none appears you may not have put enough.

The idea is to squeeze as much out as is possible ensuring that only enough to fill gaps is left, on that we all agree. Forcing the device down by external pressure helps make sure any excess is forced out without relying on the devices own hardware to accomplish.

The center daub verses the even spread is debatable either way. RCA back in the late 60s told us to use the center daub and let it spread out on it's own. Their reason was to avoid air pockets. On small devices like transistors, that's what I do. On larger devices, I don't think enough pressure can be exerted to ensure a large area can force enough compound out of the joint, so I tend to carefully spread as thin a layer as I can accomplish.