Keep "dead copper pours" on PCB that needs cooling? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: January 18, 2024, 06:18:15 pm
content: Hi,We have a 4 layer board with some linear regs on it and loads of tracking and a micro and some slow comms.When i do the copper pours, there are several areas of dead copper pour. As you know, theseare said to behave like antennae, and interfere with the operation of this board itself, and anyother boards around. Though i wish to keep the bits of dead copper in this board, as it addsto the overall copper cooling for the linear regulators.Do you agree this will be fine?

author: Siwastaja
author_rank: Super Contributor
timestamp: January 18, 2024, 07:29:10 pm
content: Just via stitch them to ground and you are fine, then they are advantageous. Sure, it's more work for you, for relatively small gain. And if you need really dense routing on the opposite layer or mid layers, then the vias take room, unless you pay premium for blind vias. But it's not usually that bad if you use the smallest drill size and minimum clearance.Only leave unconnected antennae if you are sure all signals close-by are free of high frequency components (slow switching or DC) - and probably not even then, because if you are interested about thermals, those vias help, too; unconnected copper not so much. Usually your regulators would have thermal pads connected to the GND net.

author: Gyro
author_rank: Super Contributor
timestamp: January 18, 2024, 08:10:35 pm
content: It seems to me that this is effectively a double post and the OP has people replying to both of them!https://www.eevblog.com/forum/beginners/ground-loops-created-in-pcb-copper-pour/new/#new

author: floobydust
author_rank: Super Contributor
timestamp: January 18, 2024, 08:29:20 pm
content: His venture is doomed, no amount of copper can save him. He has to add a pre-regulator buck dropping the 20V down instead of using the linear's.Until then I guess we get a dozen posts about it to appease insecurity, as if a part of him knows it's going to cook eggs.

author: ataradov
author_rank: Super Contributor
timestamp: January 18, 2024, 09:03:27 pm
content: He was already figuring out how to conduct the heat away from plastic packages a few days ago.OP, foreigners you constantly rant about are more qualified to perform your job. What were you doing all those 40 years of experience that you are asking questions first year students will know the answer to?

author: jpanhalt
author_rank: Super Contributor
timestamp: January 18, 2024, 09:40:28 pm
content: Quote from: ataradov on January 18, 2024, 09:03:27 pmI think he is looking for an employer who will give him a negative recommendation so he can retire. Unfortunately, all those inept employers are smart enough not to be honest.

author: floobydust
author_rank: Super Contributor
timestamp: January 18, 2024, 10:36:04 pm
content: The (SOT-223) semiconductor manufacturer's intent is heat transfer through the tab... onto a copper pour.Cooling parts from the topside, through plastic - kinda silly, indicative of low intellect. Even the 'foreigners' won't do it - I've chinese gizmos with thermal pad and heatsink (all sticky backed) that are squished onto the solder side, on a copper pour. Heat transfer involves via's, not plastic.Will OP ever get more room on his too small designs, or a cooling fan? Or learn how heat transfer works, the Laws of Thermodynamics, thermal management?I guess he's in a lesson right now.