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FrozenGate by Avery

Eagle PCB design software help!

Fiddy

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May 22, 2011
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G'day,

A question for someone in the know,

Im making my first PCB and im pretty much done but ive found what i think is a problem.

ive got a big polygon on each side of the board (GND is top ,12V+ is bottom) and when i connect pins to the polygon i get this cross-hair looking connection to the polygon, see this photo:

polygonconnections_zpsaa0df7b4.png



Is that normal to send of to get the boards made?

if not, how to i get a better connection like with other connections that arnt to a polygon?

Cheers! Fiddy.
 





Hey mate, replied to your PM :)

For anyone else wondering, it's a technique called "thermal relief", it makes soldering to the pads a crapload easier because all the heat isn't sinked away to the copper as fast :)
 
Its about as good as any other trace to pad connection, except there are 4 connections there, not just 1. So, it should technically be better. :)
 
Equally important, whatever you solder to that pad/hole has a solid connection, rather than a cold joint, or damage from overheating.
 
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If it's for a very high current thing, like a tesla coil, I'd recommend at least thickening them a bit so they don't become instant fuses when you discharge the caps, but apart from that, should be fine. A general rule of thumb is allow 10mil of trace for 1A for 10C rise :)
 
If it's for a very high current thing, like a tesla coil, I'd recommend at least thickening them a bit so they don't become instant fuses when you discharge the caps, but apart from that, should be fine. A general rule of thumb is allow 10mil of trace for 1A for 10C rise :)

Yeah it is actually, ive redone that guys plasma speaker board :D

Ill have to find out to make the copper pour connection take up all of the pad or make the 4 small connections on the pad bigger, i saw benmvw do it on his benboost:

36482d1328852762-free-diy-open-source-boost-driver-tested-working-ld-boost-driver-lm3410-r6-fork-again-r9-back-.png
 
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Hey replied to your PM but ill say it again here for anybody else.

To make them solid in eagle go in design rules and on one of the last tabs (second to last I think) change thermal isolation to 0.

I've never had any problems with it being hard to solder and I like to keep all my connection solid. Especially when you have a surface mount part in dpack or something. It wont connect the tab to the ground plane except for 4 tiny connections. You definitely don't want your hot parts thermally isolated like that.
 
Hi, thanks for the info @benmwv. I was going through this thread and I still have one little question, this is just a normal trace, the polygon. Essentially it’s nothing different than the other traces on the board except for its shape which isn't perfectly round. Theoretically speaking, how does it work? I searched on google and found out that thermal relief means connecting a PCB to a copper pour using a thermal connection which essentially is just spooks of copper connecting it to the surrounding board. I'd be thankful if you can explain this a little more. Thanks for the info anyways.
 
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