PCB Etching – All There Is To Know

Printed Circuit Board Etching also referred to as PCB Etching is the process in which a selective material is removed from the surface of a printed circuit board with the help of a chemical action that involves an etchant or an etching agent. Etching generally eliminates the areas with copper that you do not wish to be present on your printed circuit board.

PCB Etching comprises of two basic methods in order to remove the unwanted copper from the copper covered substrates so as to form electronic circuits namely:

• Mechanical Etching: Mechanical etching requires machine along with a special cutter for the purpose of removing a thin strip of copper from the periphery of every pad and trace. This electrically separates the circuit element from the remaining part of the foil.
• Chemical Etching: Chemical Etching depends upon the action of a liquid that is corrosive in nature so as to dissolve all the unwanted copper in order to characterize the circuit board you desired.

Usually PCB etching is done by immersing the board totally in the chemical and then stirring it up, blowing air through the bath. The copper that we wish to leave on the printed circuit board will be protected with the help of an material resistive to the etchant.

Etching needs to be controlled carefully in order to ensure that only the copper that you want to be removed is separated. One should keep the following things in mind:

• Over etching can result in undercutting of the etchant resist, which can in turn cause serious damage to the edges of the tracks as well as the pads.
• You should usede-ionized or distilled water for rinsing and then inspect the pattern for the areas that are not completely etched.
• In case you find any areas that are left from getting etched, repeat the process for another 30 seconds and then re-examine. If these areas still persist, eliminate them using a razor. Continue doing this until the circuit board is free from any defects.
• After completing the process, rinse the PCB thoroughly using water

But PCB etching can cause some defects as well:

• Non-etched Copper: The copper areas that were not able to be etched completely are acceptable only if they do not cause any short circuits.
• Pits: Small pits through which the copper has been not etched correctly can be acceptable only if they are benign. They can be an outcome of bad protection of the copper through the resist.
• Undercut: While etching, the sidewalls have a tendency to etch sideways and generate an undercut action. The degree up to which this process occurs is called the etch factor which can be characterized as the ratio between the depth to the side attack. Immersion etch methods usually lead to a "low etch factor".

Quite a lot of different kinds of etching chemicals are used in industrial processing including chromic/sulphuric, ammonium Per sulphate acid and ferric chloride. To know more about PCB wizard full, visit Pcbcart.com.

About The Author

James Whitehall is an expert when it comes to printed circuit board manufacturing and design. He loves writing interesting articles and blogs about the topic and recommends PCBCart.com as the name to trust if you are looking printed circuit board fabrication services and support