8. PCB Production

Hero Shot of the Week

Summary

Summary on how it is supposed to be & my feelings.

	Vinyl	Photosensitive	Laser Engraving	Milling
Time	Production Quite fast installation can take time as you will need to transfer your traces	Takes time with chemicals	On the Slower depends on parameters	Milling can take time depends on mill
Pollution	None	high (acids & other chemicals)	Depends on FR type & copper sublimation	Depends on FR type
Traces	not that good with smaller traces	really good	really good	good
Short circuits	None	none	none	possible
PCB Size	Depends on copper tape size can be infinite	depends on machine	depends on machine	depends on machine
ease of use	easy	needs proper setup	on the easier side	medium difficulty

Work Process

Calendar

Date	To be done	What was done
Thursday	- 9h Santi meeting - 10h local meeting	- Santi is a nice guy - Intro to stuff - Vinyl Cut
Friday	- FabLab normal work morning - 3D Print PCB	- Normal work - PCB Chemical prod
Saturday		- Documentation
Sunday
Monday	- Morning Optic Laser PCB - Bantam PCB	- PCB engraving - Bantam CNC
Tuesday	- FabLab normal work	- documenting when free
Wednesday	- 12h Local - 13h Regional - 15h Global	- Its RUUUSH TIME

Introduction

Henk and Erwin made an introduction.

They showed us how to use the little PCB CNC and how to control it from ModsProject

So I have a lithography machine but I guess I can put that away into a cupboard and forget about it.

My work

Vinyl Cutter

So I wanted to try out to make a battery level indicator. For some reason most of them are doing it with 15V. I want to use it for 1.5V AA & AAA batteries.

The simplest one I found is this one.

That I will combine with this table.

The LED I have are the following

• RED
• BLUE
• GREEN

So I quickly did a KiCAD file. Printed to save it as PDF.

Found an online PDF to JPEG and also to PNG converter. For JPEG Silhouette Studio said that the resolution was too low. No error message for the PNG type.

After some parameter testing I tried to cut my file.

The lines are too small.

Back to KiCAD. Need fatter lines.

...

It does not work.

Even with 1mm line width. I am still loosing traces in the cutting process. 😕

From left to right: 0.2mm - 0.5mm - 1.0mm

The copper paper might be too old ?
Maybe I am doing something wrong ?
Or the cutter needs to be changes ?

Who knows. It is a fail.

Honghao Deng page who successfully cut it with the vinyl.

3D Printing - Postponed

It was postponed. The printer was in a disassembled state. But they told me that they will drop it at the fabLab when they have time so I can play with it next time.

Video of 3D Printing with Solder

Geoffrey's labs - Chemical Process

In Geoffrey's Lab they are working on a Modified CNC where they have a CNC head AND a laser head. It is still Work in Progress.

Than we needed to do some PC stuff. First I export my file to gerber. Than we imported it into FlatCAM where the toolpath was generated. It is in this program where it is also chosen what part is done with which head. Than the output NC file is imported into the control program of the Laser/CNC.

Than we used a FR4 copper plat with a photosensitive layer. We engraved the design onto it. I made a simple design (same as vinyl) for testing. We did not use the CNC head as there was no need.

After that we dissolve the photosensitive part that was hit with the laser.

Than we put it into an acid bath.

You can see the before and after.

Than we rinse and clean. And the result is

weird...

The machine is still in work in progress but at least I got to see another method of fabrication. And the laboratory.

There machine concept is somewhat similar to this hackaday article but instead of engraving they are doing it with photosensitive layers and chemicals.

Nico's Lab - Laser Engraving

Nicola recently got the xTool F1 Ultra 20W Fiber & Diode Dual Laser Engraver at his work place. So we tried it out. It was the first experience for both of us.

In the following images you can see the Laser, extractor and a security USB. If the USB is not installed the laser wont start.

It is a dual laser so the optics need to be perfectly aligned.

Than as my KiCAD was in version 9 and to save some time as Nicola needed to be elsewhere, we tried one of his PCB design. We needed to import an DXF file, and version 9 has some bugs with vectors.

Note we were following this guide: How to make PCBs on a Fiber Laser

After some tinkering in the app for this laser we setup the copper board in the laser.

Than using the parameters given from the guide, we launched the engraving. Video in fast forward 500%

After engraving we cut it. Video in fast forward 200%

While cutting we stopped midway as I could see light from under the board.

As you can see from the image we should have put a second martyr to not cut into the base of the laser cutter.

The results weren't really satisfactory.
To still see if it worked Nicola quickly soldered different components onto the board.

And it works.

Our main issue was that the traces were really small. Too much material was sublimated. There could be two reasons.
Number One is that the optics aren't aligned correctly.
Number Two is that the given parameters form the git repo are not good for the copper board we used.

But for a first test we called it a success.

• Laser Cutting a PCB with a CO2 and Fiber Trotec laser cutter

Bantam - CNC

Interface Setup.

For using the Bantam CNC that we have at the FabLab I asked Axel to give me a hand on how to use it.

In the Bantam Interface menu we have several submenus that we need to be aware of.

1. Are the position of the CNC head
2. Are the view options
3. Is for the tool installed in the CNC
4. Is for the copper plate that will be milled
5. Are buttons to move the head around
6. Is for importing the Gerber file.

To import a file you select Open Files... than select the TOP Layer. Than a second windows popup where you can add other layers. This is where you add the Outline / Edge Cut.

After you imported your file you can select what layers a visible with the three buttons Traces, Holes and Outline in your project menu (image below).

This also where you select what tool you will be using to mill. You can also select in the trace depth in the advanced drop down menu.

Than if you click Start Milling you can mill the selected job. Mill All Visible will mill everything that is visible on the center view.

In the Case you have the following error message (image above), you will need to adjust your PCB design. This error means that the milling path contains a path that has a smaller diameter than the tool diameter.
You will need to verify you DRC and tool setup.
As you can see I did not verify it before hand 😅

Board Setup

Cut your board if need be. We used FR2.

I literally mean cutting it so it can fit inside the Bantam CNC.

Than give it some love with double sided tape, so it wont move when milling.

Mill End Setup

In the interface select the Change button. This will put the CNC head in a position where you will be able to change the mill with more ease.

Unscrew the previous head if need be. Than insert the new head. In the interface popup menu, select the new tool from the dropdown menu.

After making sure that the mill is correctly installed you can fasten it. Than you will need to make a Z calibration. You only need to click Locate Tool...

You finished changing the mill.

Milling

Before you start milling switch on the extraction.

Than you can hit Start Milling or Mill all visible.

The scree will show you the time left and also the tool path & position.

When the milling finished you can use flat head screws to unstuck your PCB. Make sure the bed is in the load position.

After unsticking (?) it you can use sandpaper to sand away the little copper filaments that are still stuck onto the copper plate. You take away the possible shortcuts.

Than you can go and solder.

Export file for other CNC types

PCB Editor

File > Fabrication Output > Gerber >

• F.CU
• Edge.Cuts

& Other settings if needed

.> Plot

FabAc Schedule

.> gerber2img

drag & drop onto the web

Settings:

• Black & White
• Fill edge cut to have the edge cut separately

DL the images. They now can be used in ModsProject to be cut out.

More info for GERBER:

• KiCAD to Gerber module
• Gerber to PNG converter
• Gerber to PNG converter - Quentin
• Gerber to PNG wiki

Soldering

When going through what I have at the FabLab I have found a No-Clean Flux. I did not understand what no clean wanted to mean...

So after a quick search I have found this nice article on different Flux types. TLDR: you don't need to clean the remaining flux on your PCB.

Industrial method

For the industrial method you use a syringe filled with solder paste and put it where you will put your components. Than you push your components into the solder paste.

Than when everything is in place you can put it onto a heating plate, put a cover so it has a oven effect. When your solder turns from a matt gray color into a shining one you can move it onto a cooling plate to cool it off.

And now you have a ready PCB.

Hand solder

With hand solder you melt a little solder onto the PCB, than fix you component into it and solder the other end.

This is hand soldered. As you can see it has a messier results. But I guess that also depends on the experience of the person.

PCB Board house

Henk and Sam showed us how to buy PCB from JLCPB

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Learning Outcome

So in the end I did not do (correctly) the individual assignment, as my curiosity of discovering took over and as you can see I tried different methods instead of focusing on the PCB design and prototyping. Learning what works for what, and how they work was really fun.

I think this was one of the best week as I could play with so many different new methods / machines.

But what did I learn in the end ? 🤔 I think its mostly that there is always several ways to do what you want to do. Be open minded and try out different things. You will found what works for you.

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Digital Files and Links

• KiCAD for Vinyl
• PCB Sharing Site
  • Just like thingiverse
  • Its github repo
• Programmer Serial D11C
• 2023 Bootcamp video on PCB prototyping
• 2024 Bootcamp instructor page

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Assignment Check

• group assignment:
  • characterize the design rules for your in-house PCB production process
    • Done
  • submit a PCB design to a board house
    • Done
• individual assignment:
  • make and test a microcontroller development board that you designed
    • Half Done
  • extra credit: make it with another process
    • Done

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