Project:DIY PCB Making

Under development by ChrisMc.

Schedule: Aiming at mid-March

Prerequisites: You should be familiar with EagleCAD, either through your own work or PCB Design with Eagle CAD.

Cost: Depending on numbers, materials cost is about £10 each (much less if you don't actually want to make your own PCB on the day). That includes components, boards and chemicals.

Introduction

In this workshop we will take a finished double-sided, mostly surface-mount design from EagleCAD, print it, etch it and solder on the components. With careful design and fabrication, the process described is sufficient for TQFP (and similar) packages down to 0.8mm lead pitch.

Layout Considerations

Successful DIY PCB fabrication begins at design time. You will need generally conservative design rules and some specific design constraints. This includes:

• Choice of component packages.
• Pad sizes.
• Drill & via sizes.
• Drill & via positioning.
• Track width & clearances.

PCB Fabrication

The messy stuff begins...

• Printing the lower and upper layers.
• Aligning the artwork.
• Pre-cutting the board.
• UV-exposure of bottom side.
• Flipping the board over.
• UV-exposure of top side.
• Common exposure issues.
• Applying the SN110 developer.
• Etching in Ferric Chloride.
• Applying the SN120 strip.
• Drilling the holes for vias and through-hole components.

Soldering Preparation

• Scrubbing the board.
• Applying the SN130 de-oxidiser.
• Applying the SN140 flux.

Soldering

• Drag-soldering TQFP (and similar) packages.
• Soldering other SMD components (resistors, capacitors, transistors).
• Soldering vias.
• Cleaning off excess flux.
• Pre-test visual and electrical checks.
• Power-up!