Electronics Production

Assignments

Characterize the specifications of your PCB production process

Make an in-circuit programmer by milling the PCB (program it, so that you can use it to program your board in Electronics Design week, and in other weeks)

Optionally, trying other processes.

Summary of the week
For electronic production, I only had done one plug-in PCB(printed circuit board) which called drawdio (inspired from Jay Silver). And a maker named Luke taught me the basic about Fritzing App.So this page describes my learning process to mill and to solder SMD.

I really struggled a lot about the milling and soldering, and I wasted a lot of time at finding the components. What I learnt most was I had to follow the instruction and figure out the exact process about making instead of rushing to make. Anyway, I still had a lot of fun during this assignment.

Making an in-circuit programmer 'FabTinyISP'

I chose to make an Attiny44 FabTinyISP, I searched the detail on Ali's page

Preparing the milling machine Roland SRM-20

For milling I used Roland SRM-20 Desktop Milling Machine.

First of all, practice to change the endmill of the machine. For the very first time, I feel nervous cause I worried that I would drop the endmill. And it turned out OK, even if I dropped it, it's also easy to get the endmill out. We could just open the drawer of the machine.

Change the endmill

And the wood plate is not even at Szoil, so I changed the wood plate into an acrylic base with a piece of wood on the top. And fixed the copper clad board on the wood board with hot glue.

Set the origin of Z-,X- and Y-axle

Open the program Vpanel for SRM-20, we could press the button on the panel to move the endmill and the base plate.

After moving to the right position, press user coordinate system x/y to set x- and y- axle.

It's better to use the continue moving module at first and then change into X100 or X10.

For the Z- axle , to prevent from broken the endmill, we'll move the endmill to a position near the copper board , loose the endmill to touch the board and then fasten the endmill again.

When press the button to control the endmill to move, we should remeber:

X- axis moves the table, and and Y- and Z-axes move the head.
Move the axes manually by the VPanel arrows with appropriate Cursor Step.

Continue moves as long as you push it, by which you will move near to the aimed origin.
x100 does smaller steps to get closer and
x10 0,1 mm steps to get nearby the surface.

Create .rml -files

I downloaded the .png -files Traces and Outline Cutout below,

and used fabmodules.org to make the .rml -files for Roland SRM-20 milling machine .

Generate rml for traces

Open Fabmodules.org ,input the png file ,chose .rml , pcb traces(1/64).

ouput machine "SRM-20" / X0:10,y0:10.Z0:0 / cut depth(mm):0.1 / number of offsets:1

Click caculate fisrt, to check if the cutting route is right. And then save the rml file.

Same way for the interior png file, PCB outline (1/32),same x0,y0 and z0

For one time , I didn't notice to set the same x,y,z axle, the cutting ended up like this:

So it's important to double check this part when we just start to use Roland milling machine.

I use 0.4mm endmill to cut the traces and use 0.8mm endmill to cut the interior.

I cut 5 boards for this time, in case I failed to solder the USB part.

Assembling the PCB

Preparing for soldering

First of all, I collected the tools needed: soldering iron, soldering tin, desolder braid, tweezers.Remember to wet the sponge of soldering iron for cleaning the tip of the iron.

I taped all the components on a piece of paper.

Start to solder and check if the components are soldered well with multimeter.

I failed for the first and second board, after soldering and adjusting several times. I destryed the surface and some components. So I prepare all the things again and start from the very beginning.

The hardest part for me is soldering the USB, after some practicing and my coworker taught me that I could first put a lot of tin to solder the USB then I could heat the tin and hold the board to hit the desktop, the extra tin will pop-up.

Finnally, I've got 2 boards which seemed good to use .