PCB Blog - Reasons for PCB corrosion

PCB corrosion is a natural process in which unstable materials (such as metals) are gradually destroyed (and thus become more stable) through chemical reactions. Rust is common, and iron and iron alloys decompose due to exposure to a mixture of oxygen and moisture. Corrosion is caused by many different factors, such as atmospheric corrosion, localized corrosion, electrical corrosion, electrolytic corrosion, and so on. We often see equipment failures caused by PCB corrosion during maintenance, and sometimes a component is sprayed, soaked, or otherwise immersed in liquid, which is gradual and unexpected.

Reasons for corrosion of circuit boards

1. Temperature changes

Rapid temperature changes can cause condensation within the electrical enclosure, ultimately leading to corrosion related faults. When warm and humid air is suddenly exposed to a surface below the dew point temperature of the surrounding air, condensation occurs. This will lead to gradual corrosion of component metals (commonly copper, lead, and tin in printed circuit boards).

2. Chemical process

Some circuit board manufacturing processes involve chemicals that may accelerate the corrosion process. The faster one is when a circuit board is exposed to acid. The common ones are nitric acid (usually used in fertilizers) or citric acid (used as a very common food preservative). This is a bit difficult to avoid as it is very dependent on the application. Discuss and develop a written plan with your employees to control processes involving corrosive chemicals. Ensure that your employees follow the correct procedures to distribute and use these substances around your machine.

3. Atmospheric corrosion

A common problem with circuit boards is atmospheric corrosion, where metals are exposed to moisture, which in turn exposes them to oxygen, leading to the reaction of metal ions bonding with oxygen atoms to form oxides. Atmospheric corrosion mainly occurs on copper components. Although corrosion of copper does not affect the mechanical properties of circuit boards, it can affect their conductivity.

4. Material defects

During the manufacturing process of circuit boards, there may be material defects such as bubbles, notches, holes, etc. These defects can make the surface of the circuit board susceptible to corrosion and erosion.

The manifestation of PCB corrosion

The manifestations of PCB corrosion include the following aspects:

1. The surface of the circuit board may show corrosion spots, pits, etc., which can cause circuit interruption in severe cases.

2. The metal wires or solder joints on the circuit board are prone to corrosion damage, forming virtual open circuits or short circuits.

3. The components or devices on the surface of the circuit board are prone to corrosion and erosion, leading to performance degradation or failure.

Methods to avoid PCB corrosion

1. Control humidity and temperature: During the manufacturing process of circuit boards, it is necessary to control the temperature and humidity of the products to avoid corrosion caused by environmental factors.

2. Choose high-quality materials: High quality materials have good corrosion resistance, so it is necessary to choose high-quality materials when manufacturing circuit boards.

3. Control the amount and concentration of chemicals: When conducting chemical treatment on the surface of circuit boards, it is necessary to control the amount and concentration of chemicals to avoid corrosion.

4. Strengthen maintenance and upkeep: It is necessary to strengthen maintenance and upkeep of already manufactured circuit boards, and regularly clean and repair them to ensure that there is no corrosion on the surface of the circuit board.

By taking the above measures, the occurrence of PCB corrosion can be effectively avoided, thereby enhancing the reliability and stability of the circuit board and ensuring its normal use.

PCB corrosion is the main cause of electronic product failures. At first, the effect of corrosion was to increase the resistance of copper traces on the circuit board, but as the degree of corrosion increased, the working efficiency of the PCB would decrease or even stop working.