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Etching Machine in PCB equipment is one of the crucial equipment in the electronic manufacturing process, which is mainly used to transfer circuit patterns from the copper-clad plate to the surface of the circuit board to form circuit patterns. The etching process is one of the key steps in circuit board fabrication and is usually followed by Photolithography or Screen Printing steps. With the advancement of electronic technology and the increase of miniaturization requirements, the production process of circuit boards has become more sophisticated. Etching machine, as a key equipment in circuit board manufacturing, has developed from the traditional chemical wet etching to today’s efficient and high-precision automation equipment. This article will discuss the working principle, different types, application areas, development trends, and future challenges of the etcher.
Etching Machine, UV exposure, Etching tank, etching fluid, PCB equipment.
The basic working principle of the etching machine is to use chemical reactions or physical effects (such as plasma etching) to remove copper or other metal materials to form conductive circuits on the circuit board. The process is usually divided into the following steps:
1.1 Apply a photoresist layer
The copper surface of the circuit board is coated with a layer of photoresist material (photoresist). The photoresist material undergoes chemical changes when exposed to ultraviolet light, which can protect the underlying copper layer from etching.
1.2 Exposure and development
A UV exposure device is used to transfer the circuit pattern to the photoresist layer through a mask, and then the unexposed photoresist part is removed through a development process to expose the copper layer.
1.3 Etching
Place the exposed copper area in the etcher. Depending on the etching method, a chemical solution (wet etching) or plasma (dry etching) can be used to remove the copper layer. The chemicals in the etching solution react with the copper to form a soluble copper compound, which removes unwanted copper parts.
1.4 Remove the photoresist layer
After the etching is complete, the remaining photoresist layer is removed, leaving only the copper circuit pattern.
According to the different etching methods, the etching machine can be divided into the following types:
2.1 Wet process etching machine
Wet process etching is the most traditional method of etching, using liquid chemical solutions to remove copper. The advantages of wet etching are simple operation and low equipment cost, but the disadvantage is that the etching speed is slow and the requirements for the environment are high, and it is easy to produce waste water and waste gas pollution. Wet etching equipment is usually composed of liquid tank, pump, heating device, gas flow system, etc.
2.2 Dry process etching machine (plasma etching)
Dry process etching is the use of plasma technology to etch, it through the electric field excited gas to form plasma, so as to generate ions and free radicals that can etch metal surface. Dry etching machine is often used in the manufacture of high-density circuit boards, because it has higher etching accuracy and can better handle complex and small circuit patterns. The advantages of dry etching are that the process is more environmentally friendly, does not produce waste water, and is suitable for the etching of fine structures.
2.3 Laser etching machine
Laser etching uses a laser beam to irradiate the surface of the circuit board, heating the local area to the evaporation point, and directly removing the copper layer. Laser etching machines are extremely accurate and suitable for small batch production or very complex circuit board designs.
Etching tank: This is where the circuit board is placed, usually made of stainless steel, with corrosion resistance characteristics.
Etching liquid circulation system: used to circulate the etching liquid to ensure that the liquid is evenly distributed on the surface of the circuit board, while removing the copper particles that have been etched in time.
Heating system: Some etching machines need to heat the etching fluid to increase the reaction rate and enhance the etching effect.
Gas supply system: Especially in dry etching, the gas supply system is responsible for supplying gas to the etching chamber and maintaining appropriate pressure and gas flow.
Automatic control system: Modern etching machines are usually equipped with PLC (programmable logic controller) and touch screen interface, which can realize automatic control, providing real-time monitoring, data recording and fault diagnosis functions.
PCB (printed circuit board) manufacturing: In the circuit board manufacturing process, etching machines are used to make conductive lines, connection points and other electrical structures, which are core components in most electronic devices.
Semiconductor manufacturing: Etching is a key step in semiconductor manufacturing, especially in integrated circuit (IC) and micro-electro-mechanical system (MEMS) manufacturing, where etching machines are used to remove unnecessary materials from silicon wafers.
Flexible circuit board production: With the rise of flexible electronic products, the etching process of flexible circuit board (FPCB) has become particularly important, requiring higher accuracy and adaptability of flexible board.
With the development of electronic devices towards higher integration, smaller sizes and more complex designs, etching machines are also facing increasing technical requirements:
Etching machines need to be able to handle ever smaller circuit patterns, especially in the production of high-density interconnect (HDI) boards and 5G and AI chips, where precision and etching depth control are becoming increasingly important.
With the increasingly strict environmental regulations, the development of etching machines tends to be low pollution and low energy consumption. Dry etching has received more attention because it does not produce wastewater.
Modern etching machines have gradually realized a high degree of automation, and can adjust etching parameters according to real-time data to improve production efficiency and product quality. At the same time, the application of artificial intelligence is also gradually improving the intelligent diagnosis and optimization capabilities of equipment.
6.1 The etching is uneven
Description of the problem:
During the etching process, local overcorrosion or undercorrosion occurs on the surface of the circuit board, resulting in unclear lines or uneven thickness.
Reason:
► The etching fluid concentration is not uniform.
► Etching machine operating temperature is not stable.
► The flow system is not smooth and the chemical solution is not evenly distributed.
► Improper placement of the circuit board leads to uneven solution flow.
Solution:
■ Periodically check the etching fluid concentration and ensure that it is adjusted according to process requirements.
■ Check the temperature of the etching fluid to ensure that the temperature is stable and avoid excessive fluctuations.
■ Regularly clean the liquid flow pipe in the etching machine to ensure uniform flow and liquid distribution.
■ Ensure that the board is placed smoothly to avoid tilting or uneven boards.
6.2 Etching speed is too slow or too fast
Problem description:
The etching process speed is too slow will lead to low production efficiency, too fast may lead to overcorrosion phenomenon.
Reason:
► The etching solution concentration is too low or too high.
► Etching temperature is too high or too low.
► The flow rate of the solution in the etching machine is too low or too high.
Solution:
■ Adjust the etching solution concentration according to the process requirements to ■ ensure that it is within the appropriate range.
■ Adjust the etching fluid temperature, usually the etching temperature should be between 45-50℃.
■ Adjust the fluid circulation system of the etcher to ensure proper flow rate.
6.3. Etching fluid pollution
Problem description:
Impurities in the etching solution lead to poor etching, which may cause corrosion or pollution to the circuit board.
Reason:
► The etching fluid used has not been replaced or handled improperly for a long time.
► The remaining oil or dirt on the circuit board enters the etching solution.
► There is a leak in the pipe system of the etching machine, resulting in the entry of external substances.
Solution:
■ Change or filter the etching fluid regularly.
■ Ensure that the production environment is clean, and ensure that the surface of the circuit board is free of oil or impurities.
■ Regularly inspect and maintain the pipes and connections of the etching machine to avoid the entry of external contaminants.
6.4 Incomplete corrosion or line breakage
Problem description: Part of the line is not completely removed or the line is broken during etching.
Reason:
► The concentration of etching fluid is too high or too low, resulting in uneven corrosion.
► The etching temperature is too low, resulting in incomplete reaction.
► The circuit design or graphics are unreasonable, and some parts are too small and easy to be corroded.
Solution:
■ Adjust the etching solution concentration and temperature according to the process requirements.
■ Optimize the design of the circuit board to avoid small or irregular graphics.
■ Perform a thorough inspection of the sheet to confirm that the graphic design and corrosion state are in compliance with the requirements.
6.5. Etching fluid volatilizes too fast
Problem description:
The etching liquid volatilizes too quickly during the etching process, resulting in unstable etching effect.
Reason:
► The working temperature of the etching machine is too high, which causes the etching liquid to evaporate too fast.
► The components in the etching solution are volatile.
Solution:
■ Adjust the ambient temperature of the etching machine to keep it within the appropriate range.
■ Choose an etching fluid with lower volatility, or properly seal the etching fluid to reduce volatilization.
6.6. Corrosion of etching fluid is weakened
Problem description:
After long-term use of etching solution, its corrosion effect gradually weakens, resulting in unsatisfactory etching effect.
Reason:
► The active ingredients in the etching solution are consumed, resulting in reduced corrosion.
► A large amount of impurities have accumulated in the etching fluid.
Solution:
■ Replace or replenish the etching fluid regularly to ensure its corrosiveness.
■ A dedicated filtration system is used to regularly clean impurities from the etching fluid.
6.7. The device is faulty or the transmission is unstable
Description of the problem:
The transmission system of the etching machine is unstable or unable to operate normally, resulting in production interruption or inefficiency.
Reason:
► Mechanical parts wear or malfunction.
► There was a problem with the electrical system, which caused the equipment to not function properly.
Solution:
■ Regularly check the mechanical parts of the equipment, such as motors, transmission belts, etc., for lubrication and replacement.
■ Perform regular maintenance on the electrical system to ensure the normal operation of electrical components.
6.8. Edge corrosion of the circuit board
Problem description:
In the etching process, the edge of the circuit board may be corroded, affecting the quality of the line.
Reason:
► When the etching liquid flows at the edge, the solution is easy to concentrate and lead to overcorrosion.
► The board is placed at an incorrect Angle, resulting in excessive corrosion of the edges.
Solution:
■ When placing the board, ensure that the edge of the board is not directly exposed to the etching solution, or use a special fixture to secure the board.
■ Adjust the flow pattern of the etching fluid to avoid the liquid staying on the edge for too long.
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