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The Saltwater etch process using PIC16F54 microcontroller

The Saltwater etch process This is a one-off process to produce one printed circuit board by removing unwanted copper by electrolysis in a saltwater...

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Tags: #pic16f54#saltwater
Ibrar Ayyub By Ibrar Ayyub
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CategoryBeginner Tutorials
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Reading time~5 min
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  1. The Saltwater etch process
  2. Step 1
  3. Decide how large the board has to be
  4. Step 2
  5. Score a line on the copper
  6. Step 3
  7. Make that line a deeper groove
  8. Step 4
  9. Score the other side
  10. Step 5
  11. Groove on the plain side
  12. Step 6
  13. Break it apart
  14. Step 7
  15. The cut piece of PCB laminate
  16. Step 8
  17. Decide how large it has to be
  18. Step 9
  19. Clean the board
  20. Quick Solutions to Questions related to Saltwater Etch Process:
  21. Related projects

Summary of The Saltwater etch process using PIC16F54 microcontroller

This article details a beginner-friendly tutorial for creating a custom 18-pin PIC microcontroller circuit board using a saltwater electrolysis etching process. The guide covers cutting copper-clad laminate to size, scoring and breaking the board along marked lines, and cleaning the surface before etching. It specifically addresses design choices for an 18-pin PIC (like the PC16F54), including connector spacing and component placement for breadboard compatibility.

Parts used in the Saltwater Etch Process:

  • Copper clad board
  • Ruler or straightedge
  • Knife
  • Sandpaper
  • Abrasive cleaning pad
  • Saltwater solution
  • 18-pin PIC microcontroller (e.g., PC16F54)
  • Crystal oscillator
  • Capacitors
  • Resistor
  • .1" pitch connectors

The Saltwater etch process

This is a one-off process to produce one printed circuit board by removing unwanted copper by electrolysis in a saltwater solution.

I shall illustrate the process by etching and building a board for 18-pin PIC (for the PC16F54, but any 18 pin PIC will fit in it) in the figure. It has to plug into my breadboard and accept the programming signals from my PIC programmer (just go to http://geocities.com/it2n/circuits.html and look at it).

Saltwater etch process schematics

To avoid battling with signal conflicts, the two programming pins shall not be brought to the breadboard. To play around with the clock frequency, the crystal shall be made pluggable. The Master clear signal will not be brought out.

These decisions mean a board with two .1" pitch connectors, one with 13 connections and the other with five connections, one pin spaced apart from the rest.

This is a tutorial intended for the absolute beginner, and almost every step shall be illustrated. I've even included a video of the etching process.

Step 1

Decide how large the board has to be

From the diagram, the side that plugs into the breadboard has 13 connections, and the holes in the bb are spaced 0.1 inch apart. So we need at least 1.3 inches to accommodate 13 pins.Say one and a half inches, a nice figure. Take a piece of copper clad board larger than 1.5 inches a side. Draw a line at one and a half inches.

Step 2

Score a line on the copper

Hold your ruler or straightedge firmly down on the board. Hold a knife lightly and draw across the line many times.After some time, there will be a gouge on the copper, dividing it into two.

If you bear down with the knife, chances are that it might wander and cut the board deeply where you do not want it cut - and you will be looking ruefully down on your ruined PCB stock. Be patient. Being patient has its own virtues, as life will invariably teach you.

Step 3

Make that line a deeper groove

Now, you can take the ruler away and with a little more pressure on the knife, go over the line a few more times. It will be guided by the cut, and you need a groove on that side.
Then at each edge, mark the plain surface of the board and draw a line there, too, exactly on the other side.

Step 4

Score the other side

The Saltwater etch process

Now you need a groove on the other side of the laminate, too.You will have a board with grooves on both the sides, and bending it with the fingers will be sufficient to cause it to break neatly at this line.

This is the copper side, with a deep groove.

Step 5

Groove on the plain side

This is the plain side of the laminate, with that deep groove.

Step 6

Break it apart

If you look at the edge, you will see that the two grooves on the top and bottom of the sheet has made it weak at the line and it will break easily.

Step 7

The cut piece of PCB laminate

So we have cut the laminate to about one and a half inches. It is actually a bit more than that, and that is for allowances in finishing.It will need to be sanded down to make those edges smooth and that will take away a bit of material.

Step 8

Decide how large it has to be

Now we have to decide how large the board has to be on the other dimension.We need the two connectors, the PIC, the crystal, and some capacitors and one resistor.

Arranging them all on the board, it seems that about 2" will be sufficient.

Step 9

Clean the board

Remove rough edges of the board using a sandpaper (Or go out and rub it on a level rough cement surface).Clean the copper surface using an abrasive cleaning pad - the one I use is intended for use in the kitchen, and copper is toxic so do not let your wife or mum relocate it to the kitchen after you have used it - it would also be a good idea not to borrow the one in the kitchen for this purpose.
For more detail: The Saltwater etch process using PIC16F54 microcontroller
  • How do you cut the copper clad board to size?
    Score the line multiple times with a knife while holding a ruler firmly, then deepen the groove on both sides before snapping the board.
  • What is the minimum width required for the 13-connection side?
    The board needs at least 1.3 inches to accommodate 13 pins spaced 0.1 inch apart, though 1.5 inches is recommended.
  • Can I use a kitchen abrasive pad for cleaning the copper?
    You can use one, but it should not be returned to the kitchen because copper is toxic.
  • Which signals are excluded from the board design?
    The two programming pins and the Master clear signal are not brought out to avoid signal conflicts.
  • Why is the crystal made pluggable?
    Making the crystal pluggable allows the user to experiment with different clock frequencies.
  • How do you ensure the board breaks neatly after scoring?
    You must score deep grooves on both the copper side and the plain side of the laminate so bending causes a clean break.
  • What components fit on the estimated 2-inch length of the board?
    The two connectors, the PIC, the crystal, some capacitors, and one resistor fit within this dimension.
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Ibrar Ayyub

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough...