8. Electronics Production

Goals

Group Assignment:

  • [x] characterize the design rules for your in-house PCB production process
  • [x] submit a PCB design to a board house

Individual Assignment:

  • [x] make and test a microcontroller development board that you designed
  • [x] extra credit: make it with another process

Tools Used

TLDR; Nice images

Group Project

Link to full documentation here

Individual Project

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1. Testing Fusion 360

For my assignment this week planed to test using fusion 360 for cut my board from week 6.

1.1 CAM and settup

For my test I use the project tools to select a few traces just to try out posting the program.

Under my setup I defined my stock to be 160 x 100mm x 1.8mm

For posts I used the default fusion Roalnd RML post.

Under machine type select MDX-40 (note that although we are using the SRM-20 this still works)

1.2 Running tests

To suet up the machine is enter V-Panel and jog the x-y axis to aprox 5mm in from the edge of the copper and set my set origin point under User coordinates system and then X/Y

To set the z-axis I slowly jog the z axis down until it is close and I then release the grub screw and manually lower the bit down to the copper.

Note: make sure you minimize your stick out on the tool to reduce vibration, I like to have the tool jammed up pretty far in the collet before this step.

Now set set origin point -> User coordinates system -> Z

Files are loaded under Cut then your Add files before hitting Output

Shot of the file running

First cut was very hairy, but I noticed that the stock looked smooth, this is normally a sign that switching from climb to conventional will help

So I updated the toolpath from climb to conventional and the cut was much smoother

1.2 Tweeks

I was worried about my ability to solder with the pads being close to the other copper, so I wanted to experiment with using a 2D Pocket to remove all the unused copper.

The results of using a 2D Pocket to remove all the unused copper were quite impressive. The copper was removed cleanly and evenly, leaving a smooth surface for soldering.

1.3 Results

Testing continuity with the multimeter was successful.

And looking at the tool under the magnifying glass did not show any damage or chipping

2. Making my Quentorres from Week 6

2.1 Setup

For my first full cut, the first step was to create a new setup and set up my stock size.

I hide all the bodies except copper traces to create a pocket toolpath selecting each of the traces.

And then un-hide the body and select the outline of the board.

Then check each of the loops, and make sure the tool is cutting on the right side of the line using the red arrow.

In the Heights tab is set the bottom height to be 0.2mm offset from the Stock Top

Set the Multiple Depths to be each at 0.1mm

My stock to leave is 0.1mm radial and 0mm axial

Simulation of the pocket toolpath

I then set up a 2d Contour to finish the traces, in this case I was able to use the silhouette selection to select the outline of the board.

Again, in the Heights tab is set the bottom height to be 0.2mm offset from the Stock Top

And, Set the Multiple Depths to be each at 0.1mm

I then decided that the rectangular board was a bit boring.

So used an online generator to generate a squircle.

And brought it into fusion to cut it out of my stock

I also placed my company logo on the board using insert svg

I used a drill toolpath for the holes, using a boring strategy to get a 3mm ID with the 0.8mm bit

And created a 2D contour to define all the edges of the traces and then used a pocket to clear all the other material.

I used the 0.8mm bit to clear away the coper after isolating it with the 0.4mm bit

I think the traces are still a bit thin… no good :(

3 Making things flat

I thought my issues may have been coming from the board not being flat so I decided to readjust the spoilboard.

I removed the board from the machine and reaplied the tape on the bottom, making sure to cover the whole surface.

And I decided to recut the spoilboard. This was done with a facing operation in fusion with a 6mm bit.

Nice and flat!

Similar to the spoil I was very though with covering the bottom of he stock with double sided tape.

4 Trying Again - No Pocket

So this time I decided to just isolate the copper and not remove all the copper

First roughing pass

Cutting the board out.

And the finished board

And picking out my components as per Adrian’s BOM

5 If at first you fail, fail again

Laying out my parts

I noticed a bad trace so I added a jumper cable

And started soldering my way around the board.

Before I finish the board I wanted to test some code.

So in Thonny I used Run - Interperater and used the add / install Micropython wizard.

To load micropython you hold the boot button the the device while to are plugging in the usb

And while trouble shooting the code not working I tried to re-solder the first pin and … ripped the trace off.

Soooo after another failure I decided to take a break from this one and go back to the drawing board.

6 The Mil-enth time the charm

As I was running our of time and the focus of this week was production and not design I decided that the only way to get this week over the line was to use a pre-made design and program it in MODS. I set out to make Adrians other board to see if I would have more success

This is the original traces PNG from Adrians page

An this was the outline.

It was at this point I noticed that we only had a 60deg v-bit in stock and I would not be able to achieve the resolution to fit between the pads.

So I decided to use GIMP to edit the png directly

I used gimp to remove the trace on the left and add a pair of pads that I could jump over with some wire

After all my trouble with the previous board I decided to use MODS this time around

These were the setting I landed on for the V-Bit

I only had through headers but it was pretty straight forward to bend them into position

After bending

And the board after soldering.

After all my previous fails I have development a more systematic way to solder:

  • Iron is 410 deg
  • hold the iron to the pad
  • count to 5 in my head
  • feed the solder the into the pad (not the iron)
  • remove the iron and let cool
  • repeat till the board is finished

This is my jumped cable that I added in GIMP

And the finished board

basic_blink.py

import machine
import time

led = machine.Pin(0,machine.Pin.OUT)

while True:
    led.toggle()
    time.sleep(0.5)

print("Hello, Pi Pico!")

Above is my test micropython code where I get the LED on pin 0 to blink every 0.5 seconds

Success!

In Summary

This was a very difficult week. I had a lot of failure and really struggled to get things to work.

Im happy with the final result because I know I now have this board to help me test with for the next few weeks

Things I would do differently next time

Using fusion 360’s CAM was an interesting experiment but in the end did not really pan out.

I feel that it is easier to create a dimensionally accurate board in fusion as cutting at a boundary is a bit more natural but MODS overall is much more plug and play for PCB’s

Also having the option to go in and fix things pixel by pixel in GIMP is great as sometimes as a beginner its had to get the exact result I want in Fusion Electronic Design

See below link to to files created this week:

Week 8 Files

End

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