PCB Fabrication

Techniques to fabricate your own PCB at home

Introduction

This page describes the technique that i used to fabricate my own PCB. It is a common idea but may differ slightly after several years of fine-tuning.

Items that you would need:

  • Blank copper board (single or dual layer)
  • Saw or something useful to cut the copper board.
  • Sand paper (Grade 500)
  • Laser printer
  • Art Paper / Photo Glossy Paper (Art paper is easier to use)
  • Iron (for ironing fabrics)
  • Water
  • A permanent marker pen (size fine or medium)
  • Etching solution (Ferric Chloride or Copper Chloride in Aqueous Hydrochloric Acid Solution)
  • Hot water
  • Drill
  • Drill bit (size depends on components)
  • Acetone

Most of these items are available in from a hardware and electronic shops. The art paper or glossy paper is available from stationary shops and sometimes, computer shops.

Step 1: PCB Design and Layout

For the first step, you must design and print your PCB circuit. This can be done using a PCB software. There are many software available but a necessary feature is inverting the PCB circuit for printing. This feature is important since the process of transferring the pattern to the board will invert the circuit. Inverting it before printing will produce the desired image on the board. For double sided PCB, only invert the top image.

Some of the commercial software available are Protel and Ultiboard. For a fee, these software meets all of the required features to design and print out your PCB. You may try to search for open-source or free PCB designing software on the internet.

Assuming you have created your circuit image, print it on the art paper or photo glossy paper using a quality laser printer. The paper works as a medium to transfer laser ink particles to the PCB board. The image acts as a mask during etching and retains the wanted copper design. Generally, i prefer art paper since the outcome image has a better quality and less broken connections. Art paper is semi-glossy and is a thin as a normal A4 paper.

Price of the art paper.

Difference between a normal A4 paper (left) and an art paper (right). Notice the glossy look on the art paper.

After printing the image on the paper, inspect the quality of the image. If the image is blurry or has any defects, try to change to ink cartridge or find another printer.

Another key point, when designing the PCB circuit, ensure you allocate extra space on the side margin. This will reduce future complications with pattern transfer around the sides.

Step 2: Copper Board Preparation

If you are using a copper board stored away for sometime, it is likely to have oxidize. This layer of copper oxide hinders the ink particles from transferring onto the copper board and must be removed using sand paper.

The copper board in the image above has a dark oxide layer. Polish the board with sand paper until all dark areas have been removed. You may have trouble removing the oxide layer around the corners and edges of the board. This may not be a problem, assuming you have allocated additional space in the PCB circuit design.

After polishing it, wash the board with water and wipe it dry with a towel. Next, use acetone (and a clean cotton or towel) to further clean the board.

Step 3: Transferring PCB Pattern

Since your board is cleaned and oxide-free, you can transfer the pattern. Here, the idea is to use heat to transfer the pattern from the glossy paper to the copper board.

In the image below, there are two pieces of art paper with the PCB pattern for a dual-layered PCB. One of the method to align them properly is staple an (or two) unused corner while holding and aligning the patterns against a source of light. That should hold them together for the next step.

To transfer the pattern, you would need to use an iron. Set the temperature setting to maximum and allow it to heat up. Place the copper board into the stapled paper and iron the combination.

Be careful of trapping bubbles of air during the heating process. Ensure that the board (& paper) is heated properly. You may iron it a couple of times. Once you are confident that the pattern has transfered successfully, soak it in water.

Wait till the paper has fully absorbed water. As water is absorbed, the paper becomes translucent. Give it a few minutes. Once the paper has become "mushy", carefully use your fingers to rub away the paper, leaving behind the pattern.

Ensure that all traces of paper is removed. There may be thin pieces of paper stuck in between traces. Use your thumb or nails to slowly rub them off. Inspect the design for any flaws or broken lines. Use the permanent marker pen to correct the flaws.

Step 4: Etching

Ferric chloride is used to etched the exposed copper. Use caution when handling ferric chloride. Please read the MSDS for safety information e.g. http://www.jtbaker.com/msds/englishhtml/f1080.htm

Disposing ferric chloride is not an environmental problem but disposing copper chloride is. You may try Copper Chloride in Aqueous Hydrochloric Acid Solution instead.

You may buy Ferric chloride from an electronic shop. If you bought yourself a batch of solid ferric chloride, you would need to dissolve them. I suggest you use hot water but BEWARE, fumes of ferric chloride are produced when hot water is mixed with the solid Ferric Chloride.

I recommend drilling a small hole at the corner of the board. Stick in a wire and soak it in the etching solution. Once in a few minutes, dip it in and out of the solution just like a teabag. This is the best way to expose both sides of the board simulatenously especially for dual-layer PCBs. If you do not wish to drill a hole, you may soak it in and regularly shake the board.

The etching duration depends on the concentration and temperature of the solution as well as the size and design of the board. I recommend checking it constantly to ensure it is not over-etched. If it is closely watched, the outcome is pretty amazing.

Once this is done, you may store your etching solution for another day.

Step 5: Drilling

The last step before you can solder your components is to drill the holes. To do this, you would need a drill and a drill bit.

If you are using a hand-held drill, place the drill bit directly on top hole/via and slowly start drilling. Do not approach the board with a rotating drill bit. It would easily skid off the surface when it comes into contact. Repeat the process for all of the holes and vias.

Last but not least, clean the ink traces using acetone. You may use a towel or a cotton for that purpose.

The Outcome

VoilĂ !!