[SI-LIST] A Thermal Relief Question
- From: Ned.Dempsher@xxxxxxxxxx
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 16 Sep 2010 13:13:57 -0400
Thanks Josef for your response,
The pin/power supply is designed to pass 50 Amps (.08" diameter brass
material) and the resistance of the pin is supposed to be about
0.14mOhm.
So I guess the dissipation in the pin is roughly (20**2) x 0.14mOhm 56mW
The thermal relief spokes are roughly 12 mils. wide and 10 mils. long,
four per layer. on 2 oz copper.
The power tool is showing about 0.8mV voltage drop across a voltage rail
spoke which seems to correspond to back of the envelope calculations
(currently routed to two layers) which corresponds roughly to 0.8mV x
2.5Amps = 2mW each spoke.
So I hope I am ok on that.
There is confusion here however because IPC specifications say that the
temperature rise will be through the roof for these spokes but IPC is
for long traces with no heatsink and this is a very short trace to a
large 2 oz copper plane.
Ned
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