Removing the heat from the plastic should in turn drop the temperature of the metal fin some. Now does that produce undesirable thermal shifts, no idea. In my case I'm pulling heat from a little of both, but mostly the plastic.
So what does baking the chip actually fix? I know some IC's are sensitive to humidity, but this is usually only just before the high temperature of a reflow oven. The trapped moisture can cause defects when heated.
Jeff
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On 1/20/2013 6:07 PM, Dave C wrote:
Last time 'round on this topic I designed a heatsink that contacts only the metal tab parts of U800, not the plastic body. This is the intended (I think) means of getting the heat out of the chip.
The drawing of this heatsink is in the Tekscopes files page on the Yahoo Groups web site. Look for a folder titled "U800". Its in there.
Dave
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On 20 January 2013, at 2:05 PM, Jeff Machesky wrote:
Is all of this heat related? One of the first things I did when getting
my 2465BDM was strap a very large heat sink to the U800 chip with good
quality thermal compound and very secure mounting. It's larger then the
chip. It runs just over room temperature with the case on. I
measured it
with a type K probe through the vents and touching the middle of the
heat sink with a dab of thermal compound over a half hour or so time
frame.
I do notice mine drifts a tiny tiny bit on warm up, one or two mm to
the
left. It later snaps back about 1mm to the right.
Jeff
