PCB cheaper when less copper etched off? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: November 12, 2021, 09:18:23 pm
content: Hi,At 1:39:15 of this PCB layout video, it says that the more copper pour you have on a board, the cheaper it is...Is this true?I am always getting told that its the other way round, because the more copper you get etched off, the more copper they reclaim from the process, and so the board manufacture is cheaper.Which is right?

author: ataradov
author_rank: Super Contributor
timestamp: November 12, 2021, 09:27:49 pm
content: It depends. Etchant is also not free, and reclaiming not free. So it really depends on a situation. For most cases, I would say it is irrelevant. It starts to matter when you are Apple and making a ton of stuff and trying to save cents on each board.None of the retail board houses will give a discount depending on your copper pours.

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: November 14, 2021, 10:44:21 pm
content: +1 for it does not matter unless you have crazy volumesThe best thing you could do to lower your PCB/PCBA cost is to make the board easy to fabricate (not being right on the Cu & Drill clearance/size boundaries, making sure Cu pours have an even distribution so board does not warp...) and assemble (having all the components on one side, having plenty of component to board edge clearance, not pushing P&P/solder machine component capability, making the board easy to depanelize...)

author: Brage
author_rank: Contributor
timestamp: November 16, 2021, 08:01:20 pm
content: I have not heard of a manufacturer that prefers to etch away as much copper as possible. It sounds counter-intuitive to me. You start out with a sheet full of copper, in my mind you want to remove as little copper as possible. Both to benefit the product, but also for the manufacturer.On a unrelated node: That was one kick-ass presentation from Rick Hartley! Thanks for sharing it!

author: Faringdon
author_rank: Super Contributor
timestamp: November 20, 2021, 12:11:53 pm
content: QuoteThanks, when i was in lighting we always used to put components up to 0.5mm from the board edge.Is there a kind of "best value" for this clearance?, say 2mm clear from the board edge, so that the boards dont snag components in the conveyor that takes them through the oven?

author: Mangozac
author_rank: Frequent Contributor
timestamp: November 21, 2021, 11:51:55 pm
content: Quote from: Faringdon on November 20, 2021, 12:11:53 pmWe've standardised on a minimum 4mm clearance; if any less then the panel needs 5mm v-groove snap off rails added.

author: SMTech
author_rank: Frequent Contributor
timestamp: November 22, 2021, 02:58:38 pm
content: Quote from: Mangozac on November 21, 2021, 11:51:55 pmTypically if you look at equipment specs, you'll find conveyors quote a 3mm clearance requirement, and you probably want a little more than that for comfort. Pin edge conveyors in reflow ovens seem to standardize on something a little bigger. On our Heller that's 5mm but there was a 3mm option. All of these systems would prefer your panels don't get too small, somewhere around 50-70mm is the minimum size the systems can handle reliably. A scored, routed & scored or pipped&routed border is required for any board or panel that needs parts closer to the edge than that, and which option you choose depends on subsequent processes and things like overhanging components. We tend to go with a 10mm border as standard, that's a nice width that you can easily get hold of when manually handling the panel. There's often a lot of talk about stress when breaking off panel borders, frankly I think accidentally cutting something off when cropping leads is far more of an issue and you can usually easily get away with breaking them them off using a metal plate with a groove in it or a nice set of pliers, after that its a PCB cutter, mousebite clips or your own router or laser de-paneller.