Print positioning gadget for double-sided PCBs

efi222 14 Aug 2025 19:43 8 1791 Cool? (+12)

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From my observations, fewer and fewer DIY builders are producing their own PCBs.
This topic is dedicated to the handful of others who "agonise" over this subject:) Although they certainly have their own proven ways.
I usually do one-sided plates for my needs and here I have mastered this 100%. However, the day came when I was forced to make a double-sided PCB.
I tried various patents. With holes for positioning the sides, with envelopes and others, with various final results. I got tired of the centring holes. (Maybe I don't have the skill).
In the end I came up with an alternative, experimental gadget that makes it easier to position the bottom and top print of the tracks.
The mosaic to be printed has to be provided with a corner marker for both sides of the print, or a larger frame. According to this marker you need to cut one corner of the print paper for each side.

I align the plate with the adjustable "pressers" to the corner of the jig. I place the printed paper on the plate and fix it with pieces of paper adhesive tape.

I cut the corner of the plate and the printed paper slightly so that there is a better fit between the sides and the frame.

I then turn the plate over and fix it in the jig.

Continue analogously to the previous page.

The arms are connected by sunken inserts with M3 threads.

Drilled inserts. 2.1mm diameter through-hole pads. Deviations are and probably always will be. This is the third tile I've done this way. It's not too big - 170x30 mm. I haven't tested on larger sizes. But the potential I think is there.

I need to observe in which phase these shifts occur. Maybe something can be refined further.
And that's all. Greetings

About Author

efi222 wrote 630 posts with rating 1041 , helped 12 times. Live in city Toruń. Been with us since 2019 year.

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mmaker 15 Aug 2025 07:52

Hi! Quite a cool idea, if it makes the work easier, it's a success, as I myself often make double-sided PCBs for my needs and sometimes feel that it would probably be better to order and wait than to do... [Read more]

efi222 15 Aug 2025 08:54

Thanks for the response :) I did my first attempts with positioning holes too. The next with positioning the corner of the print with the corner of the plate. In the second case it is easier to achieve... [Read more]

gregor124 15 Aug 2025 12:00

I at one time developed my own method for making PCBs. I modified an old HP laser printer by pulling its fuser outwards so that when printing, the paper bypassed it, so that the applied toner was not... [Read more]

Krzyychu 15 Aug 2025 12:19

I made my last double-sided board a very long time ago, but somehow it didn't cause me any problems. First I printed the tracks on a laser printer and chalkboard paper and folded them under the light... [Read more]

acctr 15 Aug 2025 14:21

As I was recently making a double-sided PCB by my own efforts in the editor I copied the Top layer, reflected relative to the longer edge and moved it by the thickness of the laminate (1.6 mm I think).... [Read more]

efi222 15 Aug 2025 14:39

I know from experience that it is also a good idea to run a blank sheet of paper through the printer, for heating before printing proper. The paper I have shrinks about 1mm when heated on the printer.... [Read more]

LA72 16 Aug 2025 09:59

As you are designing for corners you can make rounds. https://obrazki.elektroda.pl/1641782600_1755331118_thumb.jpg You will be able to use tiles without chamfers. [Read more]

efi222 16 Aug 2025 10:24

Good point. The scribe angles have a similar dodge. https://obrazki.elektroda.pl/6464286100_1755332587_thumb.jpg I also thought of this as the hardware was already in use :) So much so that even... [Read more]

FAQ

TL;DR: DIY double‑sided PCB alignment is achievable: paper can shrink ~1 mm when heated, and “The phenomenon is already very limited by the second printing.” [Elektroda, efi222, post #21635664]

Why it matters: It helps makers who ask “how do I align both sides at home?” finish reliable boards without pro fab costs.

Typical FR‑4 thickness is 1.6 mm; mirror and offset the top layer by this to align. [Elektroda, acctr, post #21635643]
Paper may shrink ~1 mm with heat; run a blank sheet first to stabilize. [Elektroda, efi222, post #21635664]
Proven on a 170×30 mm board with 2.1 mm through‑pads using a corner‑jig. [Elektroda, efi222, post #21635139]
Expect up to ~0.5 mm via mis‑registration; plan a retry workflow. [Elektroda, mmaker, post #21635363]
Rounded-corner frames let you skip chamfering PCB corners. [Elektroda, LA72, post #21636187]

Quick Facts

- Typical FR‑4 thickness is 1.6 mm; mirror and offset the top layer by this to align. [Elektroda, acctr, post #21635643]
- Paper may shrink ~1 mm with heat; run a blank sheet first to stabilize. [Elektroda, efi222, post #21635664]
- Proven on a 170×30 mm board with 2.1 mm through‑pads using a corner‑jig. [Elektroda, efi222, post #21635139]
- Expect up to ~0.5 mm via mis‑registration; plan a retry workflow. [Elektroda, mmaker, post #21635363]
- Rounded-corner frames let you skip chamfering PCB corners. [Elektroda, LA72, post #21636187]

What is the print‑positioning gadget and how does it work?

It’s a simple corner‑alignment jig with adjustable pressers. You add corner markers or a frame to each print, trim one corner, align the PCB to the jig corner, tape the print, then flip and repeat for the other side. It improves two‑side registration without drilling. [Elektroda, efi222, post #21635139]

How do I align both sides without drilling registration holes?

Use corner markers and a jig. Trim the paper corner to the marker, push the PCB into the jig corner using the pressers, tape, then turn over and repeat. Many find this easier than hole‑pinning. “This jig makes it easier to align the corners.” [Elektroda, efi222, post #21635382]

What tolerances did people see on DIY double‑sided boards?

On a 170×30 mm board with 2.1 mm through‑pads, alignment worked but small deviations remained. The author notes this was the third board and plans to study where shifts occur. Expect minor offset and check vias before etch. [Elektroda, efi222, post #21635139]

Laminator or iron: which is better for toner transfer here?

The jig’s author irons with a laminator, not a hand iron. A laminator gives steadier heat and pressure, reducing slip during transfer, especially when both sides are taped. If you use an iron, expect more variability across the surface. [Elektroda, efi222, post #21635382]

How do I prevent heat‑shrink from wrecking alignment?

Pre‑heat the printer path. Run a blank sheet to warm the fuser, then print both sides. The paper used shrank about 1 mm when heated, but the second printing reduced the effect. Print pairs consecutively for consistency. [Elektroda, efi222, post #21635664]

What is the “envelope” method and when should I use it?

Print both sides, fold under light to align vias, tape three edges to make an envelope. Insert the PCB, fix it so it can’t move, and pass through a laminator. Some movement can occur, but it’s minimal with careful taping. [Elektroda, Krzyychu, post #21635531]

What common failure modes should I expect?

Holes may misalign by ~0.5 mm after ironing; then you strip toner and restart. Underdried paper can blister, which is hard to remove. Some yellow transfer papers can crack toner when bent. Plan for occasional rework cycles. [Elektroda, mmaker, post #21635363]

Any prep tips for the printouts before transfer?

Dry the printed sheets on an iron until the toner starts to shine. Then align and tape the two prints toner‑to‑toner using Kapton tape. This reduces moisture‑induced blisters and improves adhesion during laminating. [Elektroda, mmaker, post #21635363]

How can CAD help align layers on thick laminates?

Mirror the top layer and offset it by the laminate thickness, e.g., 1.6 mm. Print both drawings, bend edges to register, and transfer. Also, route to minimize inter‑layer connections under DIP parts to ease drilling. [Elektroda, acctr, post #21635643]

Can I avoid trimming PCB corners when using a frame?

Yes. Use rounded corner markers in the frame. This lets you place square‑cut PCBs without chamfers while still seating neatly into the reference corner. It simplifies setup and preserves panel edges. [Elektroda, LA72, post #21636187]

What is Kapton tape and why use it here?

Kapton is a heat‑resistant polyimide tape. Use it to hinge and secure the two mirrored prints toner‑to‑toner before transfer. It holds alignment during heating and avoids residue that some tapes leave. “I glue these prints together using kapton tape.” [Elektroda, mmaker, post #21635363]

Is there a way to transfer unfused toner without ironing first?

Yes. One maker pulled the printer’s fuser out so toner wasn’t fixed. They positioned the unfused image on the PCB, gently tapped from the back to deposit toner, then heated the laminate to fix it. The sheet could be reused. [Elektroda, gregor124, post #21635513]

How do I use the corner‑marker jig? (3‑step quick start)

Add corner markers or a frame to both prints; trim that corner on each sheet. [Elektroda, efi222, post #21635139]
Press PCB into the jig corner with adjustable pressers; tape the first print in place. [Elektroda, efi222, post #21635139]
Flip, re‑seat, tape the second print, then laminate and etch. [Elektroda, efi222, post #21635139]

Should I try photoresist or laser‑burned paint instead of toner transfer?

Both work but add complexity. One user found photochemical methods even more work for two‑sided alignment. A 5 W laser on painted laminate gave average early results; further tuning was needed. Start with toner while you iterate. [Elektroda, mmaker, post #21635363]

Will rounded‑corner frames leave a small protrusion at the start of the arc?

Yes, a slight protrusion can appear where the rounding begins, even with a hole in the corner. You can refine the frame geometry or deburr after transfer to remove the artifact before etching. [Elektroda, efi222, post #21636205]

What does DIP mean, and why avoid vias under DIP packages?

DIP stands for Dual In‑line Package. Avoid vias under DIP bodies to reduce layer‑to‑layer dependencies during manual alignment and drilling. It simplifies placement and improves yield for home‑made double‑sided boards. [Elektroda, acctr, post #21635643]