Eagle question: Calculating area - Page 1
Forum section: electronics / beginners

author: gregallenwarner
author_rank: Regular Contributor
timestamp: July 17, 2014, 07:59:36 pm
content: I realize Eagle's got a love/hate thing going on with people here. Some people love to hate it, others hate to love it. Either way, it's what I'm using because for me, it's what makes the most sense right now.I've laid out a copper fill using the polygon tool, to act as a heat spreader for a surface mount linear voltage regulator. I was wondering if there's a function in Eagle to have it calculate the surface area of that copper pour? I don't mean the overall size of the polygon, however. That would be trivial. But rather, there are little variations and cut-outs in the overall shape where Eagle automatically avoids any other nets or components that happen to overlap the area of that polygon. So I'm wondering if there's a way to calculate the resulting surface area after Eagle performs all of its magic of shaping the fill around all the adjacent components?In other words, is there a way for Eagle to tell me exactly how much copper will be in that fill? I want to use this info to calculate the maximum heat dissipation, and the maximum current I'll be able to draw from that regulator for a given temperature rise.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: July 17, 2014, 08:16:35 pm
content: the heat dissipation is subject to too may other variables for exact single digit % accuracy to mattera big part of engineering is knowing when a number is close enough to quickly move on to the next issue

author: gregallenwarner
author_rank: Regular Contributor
timestamp: July 17, 2014, 08:24:52 pm
content: So let's say I take the trivial approach and just calculate the area of the overall polygon geometrically, disregarding any cut-outs that Eagle makes. You reckon this'll be close enough to calculate my thermal dissipation?

author: XFDDesign
author_rank: Frequent Contributor
timestamp: July 17, 2014, 10:56:26 pm
content: The actual catch is a variable which Eagle (as far as I know) doesn't factor in: Copper weight (i.e. 1oz, 2oz, etc).If I'm understanding your question, your issue is that the polygon isn't a normal rectangle so it's an "odd shape" - so you're looking to calculate total copper area (and then copper volume)?Do you have a screen shot of what your copper poly looks like?

author: Prime73
author_rank: Regular Contributor
timestamp: July 18, 2014, 12:39:35 am
content: try this ulp:http://www.cadsoftusa.com/downloads/file/statistic-copper-plane.zip

author: gregallenwarner
author_rank: Regular Contributor
timestamp: July 18, 2014, 01:48:15 pm
content: @XFDDesign: You're right about the "odd shape". Although for copper volume, I'm just assuming that the copper plating will be of uniform thickness, and then depending on whether I get it manufactured in 1oz or 2oz copper, I'll just multiply the calculated surface area by the depth of the copper. So I don't need to calculate the volume from within Eagle, just the surface area. I can post a picture next time I'm at my design computer.@Prime73: I'll take a look at that file, but I'm completely new to Eagle and ULP's, so I'm not 100% sure how I'm supposed to run it. I'll do some Googling on ULP's. Thanks!