Re: gEDA-user: Thermal pad (heatsink)?

[kai-martin knaak <kmk@xxxxxxxxxxxxxxx>]

Matthew Lai wrote:

> I'm assuming if I want to connect it to some net, I'll have to make a
> proper footprint (of the original part + thermal pad). Otherwise it
> keeps telling me there is a shorted net.

You'll have to include the thermal footprint in the netlist. The only way of 
doing this (short of manual edits of netlist and *.pcb file) is to provide a 
symbol in the schematic. This pad just needs one pin, a footprint attribute, 
and a refdes attribute. I have such a pad in my section on gedasymbols:
http://www.gedasymbols.org/user/kai_martin_knaak/symbols/misc/pad.sym

The pin number of the pin in the symbol should match the name of the pad in 
the footprint. you can edit the number of the pad in pcb. Type "n" while the 
mouse hovers over the pad. Or you can edit the name in your favorite editor. 
It is the second last parameter of the Pad[...] statement. Enclose the 
number by " characters like this:

	Pad[-2500 5500 57500 5500 79000 2000 80000 "1" "1" "square"]

I set the third last parameter to "1", too, because I always forget which 
parameter is the name and which is the label. (Positional parameters are a 
bitch). 

Set the footprint attribute in the pad symbol o the name of your footprint 
and process the schematic with gsch2pcb like. The thermal pad will act like 
any other footprint and connect to whatever net you attached in the 
schematic.

(Note-to-self: This is a real world case for a multiple footprint component. 
An improved symbol/footprint management system should allow for this.)

---<)kaimartin(>---
-- 
Kai-Martin Knaak
Ãffentlicher PGP-SchlÃssel:
http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x6C0B9F53



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