Via Stitching! - Page 1
Forum section: electronics / beginners

author: Swapnil
author_rank: Contributor
timestamp: July 30, 2022, 10:35:49 am
content: Hello everyone, I am a newbie in PCB designing and started designing PCBs recently. I came across a concept called via stitching which is to achieve increased current carrying capacity of the board. I looked for the references on the internet but did not find the ones which will clear the doubts that I had. The doubts that I have regarding the via stitching are:1) If adding vias is intended for increased current capacity then what number of vias should be added and what should be its diameter?2) If there is not enough space to add bigger diameter vias, then can a large number of small-sized vias be used?3) Is there any calculation regarding the number of vias we need to put for a specific current requirement?4) Is there any guidelines regarding the clearances between each via if we have space constraints?(P.S: The trace width is 140 mils and the required current capacity is 100A)

author: tooki
author_rank: Super Contributor
timestamp: July 30, 2022, 01:49:45 pm
content: Quote from: Swapnil on July 30, 2022, 10:35:49 amMaybe if the PCB is cooled in liquid nitrogen!No amount of via stitching in the world will make that work.For a 75°C temperature rise (which is more than I’d want in a PCB) you’d need a cross-section of about 55mm2. 140mil is about 3.5mm, so you’d need a PCB trace about 16mm thick. That’s clearly not possible, even by using via stitching to combine traces on multiple layers.

author: wraper
author_rank: Unknown
timestamp: July 30, 2022, 02:03:00 pm
content: Vias don't increase the current capability, quite the opposite since you are making holes in the traces thus reducing usable trace width. A lot of vias between the layers are usable when you are transferring a lot of current from one layer to another. So for example you could run parallel traces on multiple layers and connect them with a lot of vias on their ends

author: Gyro
author_rank: Super Contributor
timestamp: July 30, 2022, 02:10:47 pm
content: Reading the OP's other threads, it looks as if it is for some kind of military style drone, so it may be short lived anyway!https://www.eevblog.com/forum/buysellwanted/wireless-communication-module!/Hmm

author: langwadt
author_rank: Super Contributor
timestamp: July 30, 2022, 02:19:33 pm
content: Quote from: wraper on July 30, 2022, 02:03:00 pmvias aren't just holes, they are plated. so the "missing" horisontal copper is replaced with the vertical copper in the walls of the via

author: wraper
author_rank: Unknown
timestamp: July 30, 2022, 03:55:06 pm
content: Quote from: langwadt on July 30, 2022, 02:19:33 pmFar from replaced. Copper layer in vias is thinner (higher resistance) and in location where only a little of the current will flow since it will need to go way out of the shortest path (again higher resistance). So via plating will compensate for copper missing from the hole only a little bit.

author: tooki
author_rank: Super Contributor
timestamp: July 30, 2022, 04:09:39 pm
content: Not that it matters here. With or without vias, there’s no way a 140mil trace is going to carry 100A for more than a fraction of a second! :p