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- September 27, 2022
- PCB knowledge
- (0)
- 05 mins
PCB etching – a complete guide
PCB etching is a vital part in PCB manufacturing. It is used for extracting copper from the board to get the ideal circuit sequence. While it may appear simple, PCB etching is somewhat complicated. Furthermore, different techniques of PCB etching can be employed, each comes with its advantages and disadvantages. We’ve crafted this guidance to assist you in better comprehending the etching procedure. Today, we will also talk what PCB etching is and why it is required to perform.
What is PCB etching?
The procedure by which excess of copper from a printed circuit board is extracted is known as PCB etching. Only the needed circuit persists after all surplus copper has been eliminated from the circuit board.
Manufacturers develop a design for the PCB before proceeding towards the procedure. Once the design is developed, they transmit the required board design onto a PCB using Photolithography technique. This is the framework that defines which copper parts must be eliminated from the board.
What is the purpose of PCB etching?
PCB etching is one of the most crucial steps of board development. Without this technique, you won’t be able to design the circuit board you want. You must now be curious to know why this technique is required. Its purpose is to remove the copper from the board. PCB etching is particularly used when someone needs to develop a PCB.
In any circuit board, a lot of connections are present. This technique involves copper to link various connections on a board. Some chemicals are needed to make the traces of copper for these connections. However, copper can also spread over the surface of PCB. This is why PCB etching is used to clean the circuit board from unnecessary copper except at the points where connections are linked.
By using the PCB etching technique, you can be sure that the copper is completely extracted from the board and you can now effectively get the required pattern.
What are the types of PCB etching?
There are four types of PCB etching. The sorts of etching accessible to you are:
•Acidic etching
•Alkaline etching
•Chemical Etch
•Laser Etch
Acidic Etching
This PCB etching process is beneficial. Acid etching entails removing the Copper from internal layers in circuit boards. This type of PCB etching exists with FR-4 panels. Acid etching is a wet process and is available in solution form. The special feature of acid etching is that it does not cause any kind of reaction in the solution. But this PCB etching also has a disadvantage: it takes much longer than alkaline.
Alkaline PCB Etching
This type is faster than Acidic etching. Alkaline etching is another important type of PCB etching. This technique is used when you have to remove unnecessary copper from the outer layers of the PCB. Alkaline etching is assumed to be somewhat better than acidic since it scrubs the copper in a shorter time.
Chemical Etch
In this type of PCB etching, the solutions ammonium per sulphate and ferric chloride are used. For PTH, further stages of electroless sediment are performed after the pits are prepared. After that, Copper is plated to make up the consistency. Next, the circuit boards are filtered and coated with tin.
Laser Etch
This type of PCB etching is used for specific, computer-controlled hardware. During this type of PCB etching, a high-powered laser cuts out path lines on the PCB’s substrate and smashes off undesirable copper traces. Laser etch reduces the number of stages in the procedure. It also prevents any acids or harmful chemicals from being used.
With the help of a laser beam, the copper present in the bottom layer of the board is revealed and later the desired pattern is obtained by cleaning the copper from the board using the acid technique.
Materials and necessary tools you need to etch a PCB
The required materials and tools for this PCB etching process are given below:
1.PCB board
2.Soldering iron
3.Glossy paper
4.Drill machine
5.Steel wool or Sandpaper
6.Laser Printer
7.Cloth Iron
8.Marker pen
9.Etchants such as iron oxide chloride, hydrogen chloride, and hydrogen peroxide
10.Protective glasses and protective gloves
Which chemical is used for PCB etching?
The following chemicals you can use for PCB etching:
Ferric chloride (FeCl3) – used for the etching of most metals, safe to use, recyclable, can be regenerated and reused.
Concentrated Hydrochloric acid – Used for the etching of specialist metals and alloys.
Concentrated Nitric Acid – It can also be used to dissolve copper from a PCB.
Ammonium Persulfate – It is used to create a cleaner copper etchant solution. The advantage of this chemical is that its solution remains transparent, no gas bubbles are ejected, and the board does not drift.
Ammoniacal etchant – They are widely used in mobilizing, tinning, and gluing fluxes to eliminate oxide coatings from metal. However, it has a very smelly nature and only used in the form of spray etching.
What are the steps in PCB etching?
The following steps will lead you to perfect PCB development:
1.First, design the PCB you want.
2.Print out your PCB design onto a Transfer Paper.
3.Sand the Copper Plate.
4.Wash the copper with some Water and rubbing alcohol and let it dry.
5.Sculpt the drawings and insert them on the copper face down.
6.Operate the copper plate with the design via a laminator 5-7 Times.
7.Put the plate in a freezing bath.
8.Execute PCB etching technique.
9.Wash it with water after the removal of copper.
Safety measures while undertaking PCB etching
You should be careful when trying to doing PCB etching using equipment and chemicals. Below are some safety measures you must follow while working on PCB etching:
•Before starting the PCB etch process, make sure that you know everything about PCB etching pocess clearly and you are able to use all the tools and equipment correctly. If you aren’t sure of something, go ahead and ask an expert.
•Wear protection glasses, safety gloves and an apron all the time.
•Do your work close to an eyewash station, or ensure a phone and a first aid box by your side.
Some issues while etching a PCB
We know about some common PCB issues users face and we have made the list of these problems. By identifying these points, you can remember them while developing your PCB. So you can avoid these issues.Here are some issues you may face while etching a printed circuit board.
•Over- etch
•Acid Traps
•Chemical Leakage
•Waste Disposal
Summary
Although PCB etching looks straightforward, it is much more complicated. Obtaining a required PCB is not easy as you think. The process needs you lots of safety measures, materials & tools, and to follow all the steps. Do it carefully and don’t miss any step. We hope this guide can increase your knowledge about PCB etching.
