Thanks Victor, interesting thread. If it is humidity based then I'm glad I live in Arizona. Seams like leaving them for a long time packed in silica gel might also help. Interesting in any event.
Jeff
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On 1/20/2013 6:37 PM, victor_j_silva wrote:
It may fix some of the U800s that have failed:
Please search this forum:
"U800 baking"
This has been discussed ad nauseam.
--Victor
--- In TekScopes@... <mailto:TekScopes%40yahoogroups.com>, Jeff Machesky wrote:
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
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
-=-=-=-
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
