[eagle] New Data

Dick Jansson-rr rjansson at cfl.rr.com
Sat Oct 20 16:19:14 PDT 2007


John:
 
I have just completed some analytic evaluation of the clamping of the PCB
generously to the side edge of the Baseplate, as in the revised design shown
to you on the E05 60 Module, its new designation.
 
The model consists of a 80x80mm PCB, with 72x80mm freely hanging away from
the Baseplate. One model uses only a single 1.4mil copper ground plane layer
and has the IC mounted 52mm from the clamped PCB to the Baseplate. The
second model uses a dual 1.4mil copper ground plane and has the IC mounted
20mm from the clamped PCB to the Baseplate.
 
I ran a series of four power levels in the IC, 0.25W, 0.50W, 0.75W, and
1.00W. The IC temperatures are fairly linear with power for each case. In
the first case with the IC mounted pretty far away, 1.00W of power caused a
temperature rise of 38.4°C above a 20°C Baseplate and enclosure. For the
more closely mounted IC, the temperature rise for the 1.00W case is 28.6°C
above the 20°C of the Baseplate.
 
You can detect that the temperature rise does not seem to be very linear
with the distance from the Baseplate. As this data is still quite new for
me, I do not have an explanation for this effect. I did, however, want to
make you aware of the data so that you can start to plan to see what you can
do in the URx redesign. I plan to do some variations on these two cases to
try to understand the processes more completely. I do, however, have to wrap
up this data process so that I can complete my presentation in Pittsburgh. 
 
I hope that this information will be of use to you.
 
’73,
Dick Jansson, KD1K
 <mailto:kd1k at amsat.org> kd1k at amsat.org 
 <mailto:kd1k at arrl.net> kd1k at arrl.net 
 
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