How can I interconnect and solder stacked single-layer PCBs? - Page 1
Forum section: electronics / projects

author: kitaprak
author_rank: Newbie
timestamp: April 29, 2025, 07:01:02 am
content: I’m designing a planar transformer on an E-core that requires 8 layers in total (4 primary layers and 4 secondary layers). I can only place two layers on my main board; for price considerations I want to design the remaining six layers as individual single-layer PCBs to stack and solder together.My main questions:1. What interconnect strategy to use?2. What construction, sizing and layout best practises can be used here?Some more details:1:40 winding ratio, center taped2 parallel winding layers for each primary winding (1 turn)4 serial layers for secondary winding13A_rms on primary winding(I've also posted this question to Stack Exchange)

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 29, 2025, 08:05:01 am
content: Quote from: kitaprak on April 29, 2025, 07:01:02 amIs that really cheaper ?2 layer PCBs are pretty much the bottom of the price curve, and they can reduce your solder joint count, with multiple vias, which come essentially for free.How many are you making ?

author: kitaprak
author_rank: Newbie
timestamp: April 29, 2025, 08:21:29 am
content: Good point, I’ll actually go with 2-layer PCBs, but I can only use the top half to keep proper isolation between windings. But I still need to stack boards and connect them, which brings me back to the original question.I'm really unexperienced and I'm looking for the general approach for connecting stacked PCBs, I would be really interested design and soldering techniques.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 29, 2025, 08:51:11 am
content: Quote from: kitaprak on April 29, 2025, 08:21:29 amAlso get some prices checks on 4 layer boards, smaller areas are not that costly.Anything that can reduce your solder joints and PCB area helps, and you may be able to separate low voltage windings with glass fibre tape.

author: daisizhou
author_rank: Super Contributor
timestamp: April 29, 2025, 08:52:25 am
content: Look at the pictures, are you interested?

author: kitaprak
author_rank: Newbie
timestamp: April 29, 2025, 08:55:34 am
content: QuoteThank you, I will try to come up with something, but I need 1 oz inner layer and it increses the price significantly at JLCPCB. If you have any tips on PCB layout or soldering techniques for connecting the stacked layers reliably, I’d really appreciate it. I'm open to any practical tricks you’ve seen or used!

author: kitaprak
author_rank: Newbie
timestamp: April 29, 2025, 09:02:16 am
content: Quote from: daisizhou on April 29, 2025, 08:52:25 amThanks for sharing the pictures, would you be willing to share the source files?

author: daisizhou
author_rank: Super Contributor
timestamp: April 29, 2025, 09:06:49 am
content: Quote from: kitaprak on April 29, 2025, 09:02:16 amI don't have the source file.This is the physical PCB transformer that I disassembled.Upon closer inspection, one of them has already been damaged,I plan to remake it, but it looks like it's over 20 layers. Do you need to see detailed pictures?

author: kitaprak
author_rank: Newbie
timestamp: April 29, 2025, 09:11:41 am
content: Quote from: daisizhou on April 29, 2025, 09:06:49 amYes, that would be really nice.

author: daisizhou
author_rank: Super Contributor
timestamp: April 29, 2025, 09:33:58 am
content: Quote from: kitaprak on April 29, 2025, 09:11:41 am

author: mtwieg
author_rank: Frequent Contributor
timestamp: April 29, 2025, 08:25:13 pm
content: I have good news, there is indeed a standard and cheap process for stacking multiple one or two layer PCBs and creating interconnects between them.It's called a multilayer PCB.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 03, 2025, 06:51:25 pm
content: PCB "through pins"? Veropins etc.I used them in the dark days of DIY dual layer pcbs. A bit of tinned copper wire works a treat if your a skinflint.https://www.mouser.in/new/mill-max/mill-max-press-fit-pcb-pins/Castellated edges can be used to quickly solder up a stack of pcbs.Use a cheap pcb fab to make you a multilayer pcb. It'll be cheaper than a DIY version.A stack will be a moisture magnet unless you glue/ seal the layers together.