PCB Corrosion

Corrosion refers to degradation of the board material through any chemical action with the service environment; it is caused by interaction with chemicals, specifically metals: copper traces, solder, and so on, which tends to increase their resistance by disrupting connectivity that may render the board useless. Understanding its forms and causes becomes important if it has to be kept away from a piece of hardware.

Types of PCB Corrosion

Types of Corrosion Most of them are seen in rather different guises:

General Corrosion

Also known as atmospheric or uniform corrosion, this common form occurs when copper on the PCB reacts with elements like oxygen, sulfur, and moisture. This reaction produces copper oxides or sulfates, which increase electrical resistance and impair conductivity. Visually, this can lead to discoloration and powdery deposits on the board, but it is often straightforward to detect and manage.

Localized Corrosion

Localized corrosion involves the attack of specific areas of a PCB, including:

Pitting Corrosion: Small, deep holes in copper traces characterize this kind of corrosion. These are very difficult to trace and may only be determined when substantial damage has taken place, which can affect board failure.

Crevice Corrosion: A type of localized corrosion under components, where stagnant moisture and residues can promote corrosive reactions.

Filiform Corrosion: It initiates under protective coatings and forms thread-like structures that grow in all directions across the PCB, threatening its other areas.

Galvanic Corrosion

Galvanic corrosion occurs when two unlike metals are in electrical contact in a common electrolyte, resulting in one metal corroding preferentially to its rate of attack when it exists alone. This often occurs at their junctions, like on solder joints.

Dendrite Formation

Dendrites form because of ionic contamination due to moisture on the surface of the PCB, which forms conductive pathways and causes short circuits across the board.

Intergranular Corrosion

This form affects the grain boundaries of copper, where impurities accumulate, making these areas more susceptible to corrosion. It often compromises structural integrity and electrical performance.

Causes of PCB Corrosion

Several factors combine to cause corrosion in PCBs, including:

Moisture and Humidity: High levels of moisture in the environment accelerate the electrochemical reactions that lead to corrosion.

Salt and Contaminants: The presence of salts, especially in coastal or industrial areas, can result in rapid corrosion.

Temperature Fluctuations: Repeated expansion and contraction due to temperature changes can create microfractures, exposing the board to corrosive environments.

Material and Manufacturing Quality: Poor quality in materials or manufacturing defects can leave the boards more vulnerable to environmental damage.

Preventing PCB Corrosion

Effective prevention strategies are essential to safeguard PCBs:

Conformal Coatings: Applying protective coatings such as acrylic, silicone, or epoxy can shield the PCB from moisture and contaminants. These coatings form a barrier, preventing corrosive reactions.

Environmental Controls: Storing and operating PCBs in controlled environments with regulated humidity and minimal exposure to pollutants can significantly reduce corrosion risks.

Quality Materials: Employ top-grade materials both for the PCBs and components. Rigorous quality control at the time of manufacturing may ensure early detection of any defect that might be potentially hazardous.

Regular Maintenance and Cleaning: Regular inspections and cleaning using isopropyl alcohol or specialized PCB cleaning solutions will avoid the buildup of contaminants responsible for corrosion.

Design Changes: Consider operational environments during design by employing protective enclosures and strategic component placement to minimize exposure.

How to Manage and Repair Corrosion-Damaged PCBs

Corrosion-damaged PCBs require immediate attention to limit damage and restore functionality to the boards:

Inspection and Cleaning: The PCB should be visually inspected, and multimeters should be used to check for any abnormalities in resistance or conductivity. Use baking soda paste or isopropyl alcohol to clean the corroded area to remove any residue.

Repair Techniques: Damaged traces can be restored using a conductive pen or copper tape. Beyond that, replace highly corroded components to maintain the functionality of the board.

Tools to Remove Corrosion

The following are some of the tools and other materials that can be used in the process of removing corrosion:

Baking Soda: This will help in making a soft abrasive paste for cleaning, especially when combined with water.

Isopropyl Alcohol: A very good cleaning agent which evaporates easily, hence minimizing the risk of causing further damage.

Deionized or Distilled Water: For rinsing purposes without depositing ions, which would increase conductivity.

Compressed Air: It can be used to blow off loose debris and moisture from the board.

In content marketing for PCB solutions, it is important to bring out the understanding and prevention of PCB corrosion. The longevity of electronic devices depends a lot on how their core components are managed proactively. Recognizing the forms and causes of PCB corrosion and introducing strategic preventive and repair measures will considerably improve the reliability and lifespan of your electronics. Well-informed design and maintenance practices are required to avoid costly repairs and ensuring the functionality of devices over time.