PCB Prototyping

Here we will document various ways of prototyping PCB's

22 June 2020

A common PCB manufacturing method of toner transfer was tested. Here a laser printer is used to place toner on photo-paper of the PCB. This is then ironed to a cleaned copper PCB blank. In water, the photo-paper can be removed leaving only the toner which can act as an etching mask.

A copy of the Velocity PCB was transferred to a copper PCB blank using this method. The result is shown in the image below. As can be seen the transfer process was not perfect, (and the masked area is the negative of what it should be) however the areas which did stick stuck quite well. Scratching with a fingernail does not remove the coating.

• 

  Copper PCB blank with toner solder mask

Below is the result after etching and removing the toner. Evidently, the circuit was etched for too long and the masked areas over expanded to remove some of the finer detail. Despite this the process worked surprisingly well for a first attempt. It is thought that better results could be achieved with finer tuning of the technique.

• 

  Copper PCB after etching

4 May 2021

We are again looking at PCB prototyping as turn around time for the PCB's is really a major hurdle to faster development times. In-house PCB printing seems unfeasible especially with the capital needed for the most advanced devices however the soldering of the components is viable for us to do.

This would involve reflow soldering, and use of stenciled solder paste.

The double sidedness of the PCB's presents an issue as well as heating up to solder the one side of the PCB will cause components on the other side to fall off. To fix this we can use 2 temperatures of soldering paste. We use the higher temperature paste first and then the lower temperature paste for the other side.

In reading it seems that the Voltera is able to do re flow soldering on once PCB side. It is able to print on the solder paste and then heat up the board using internal heaters to re-flow the paste.