The EthNode – Hardware build

A quick update on the EthNode: I developed and etched a double side PCB for the EthNode last night and have just finished assembling the components. It’s a tricky build as I can’t plate the through holes with my home setup. If it works, I’ll be getting a few PCB’s professionally made!

The PCB developed with good clean traces.  I was trying to make a JeeNode too, put my inkjet printer ran out of ink and the laser version of the artwork was not dark enough.. so I guess I now know that inkjet is the way to go for printing artwork for PCB production!

Here is the top side of the PCB with a few parts added:

Ethnode - Build start

Ethnode – Build start

The back side is good a clean too, and the hole alignment is much better for this PCB.  I converted an old scanner to a light box which made alignment of the artwork quick and easy to do.

Below is a photo of the assembled PCB, you can see more on my Flickr page if that is your thing!

Ethnoe - Fully assembled

Ethnoe – Fully assembled

Another view.. from the MagJack end:

Ethnoe - Fully assembled (MagJack side)

Ethnoe – Fully assembled (MagJack side)

A close up of the only SMD part on the board (the 25LC512 serial EEPROM):

25L512 serial EEPROM memory

25L512 serial EEPROM memory

All the rails (+5 an 3.3V) are good and a quick electrical check with a multimeter didn’t show up and shorts as I guess it’s coding time..


Home PCB Production – I2C 8 channel IO board

Time to start making the I2C Relay IO board I designed up a month ago.  It’s taken me this long to get around to production because I have had to get a few things together to make this happen!

So for PCB production here is my list of things you’ll need:

  1. Artwork (KiCAD will give you PS or SVG)
  2. Artwork printed onto OHP film with either a laser or inkjet printer
  3. A light box/UV exposure box
  4. Photoresist developer (I’m using Electrolube PDN, 1 part to 4 water by vol.)
  5. Etch solution (either Ferric Choride or Sodium Persulphate)
  6. A selection of glassware
  7. Rubber gloves and eye protection (all very “Breaking Bad” sounding!)

The artwork needs to be printed out on clear overhead projector film. I always print two copies and tape the two together to get an extra dark image.

PCB Artwork doubled up

PCB Artwork doubled up

I don’t yet have a UV source so I used the sun.. works fine, 5 minutes exposure and into the developer.  The developer is spec’ed at 20C but I turned up the heat to about 28C as it was taking all day to do anything!

PCB Development - traces just starting to show up

PCB Development – traces just starting to show up

Once the image was good and clear time to take it out of the developer and rinse with water, at this point the copper should be shiny.  This takes about 5 to 7 minutes.

Into an etch bath at about 50C..

PCB Etching - start, good sharp lines, looks good..

PCB Etching – start, good sharp lines, looks good..

5 minutes later we have some action, the last of the copper is being removed.

PCB Etching - near the end of process

PCB Etching – near the end of process

Rinse again under water and dry.  The resist comes off with wire-wool or nail polish remover.

Dremel at the ready, with diameter 0.8, 1.0 and 1.2mm bits.  Forget HSS bits, drop some more cash and get solid-carbide drills, they last much better!

PCB Drilling - 0.8, 1.0 and 1.2mm drills needed for this PCB

PCB Drilling – 0.8, 1.0 and 1.2mm drills needed for this PCB

Mount up the parts.. and I’m very happy, worked first time!

I2C Relay Board - top side - Finished

I2C Relay Board – top side – Finished

Here is a close up of the tracks:

PCB track close up

PCB track close up