![]() In the presence of ionic contamination on the surface of a PCB and moisture, copper traces can grow dendrites. Although similar in nature to pitting corrosion, the difference is galvanic corrosion occurs between electrochemically dissimilar metals in electrical contact, with both metals in contact with the electrolyte. Galvanic corrosion frequently happens between copper on the board surface and the metal of a component, a gold or tin plating, in the presence of a corrosive electrolyte. Reacting with the copper, the moisture starts the corrosion process, which then has the potential to spread along the trace to other parts of the board.Īlso known as bimetallic corrosion, galvanic corrosion occurs due to the presence of two dissimilar metals. Nearby copper reacts with these materials and the corrosion starts in the cervices.įilliform Corrosion - Although a surface finish usually protects copper pads, moisture can enter under such surface finish. Compounds that produce the pitting corrosion, often hide the damage, making it difficult to detect.Ĭrevice Corrosion - Crevices under components or other hardware can collect left-over matter like flux, or other contaminants like cleaning solution. As the pit diameter and depth increase, the process ultimately leads to failure, such as discontinuity. Pitting Corrosion - Visible as holes or cavities in the copper surface, localized galvanic corrosion leads to deterioration of the conducting surface. However, localized corrosion may be of three types: The corrosion erodes the metal, causing an electrical discontinuity.Īs the name suggests, this type of corrosion limits itself to a small area on the board. Salt and moisture present in the atmosphere, especially in areas near seas, can also cause corrosion by forming a compound with copper in the track and iron/tin in the leads of components. Copper sulfate is non-conductive, and the process gradually erodes the copper, until there is a discontinuity in the copper track. It reacts with the copper on the board to form copper sulfate, a greenish corrosive powdery substance. Sulfur present in the atmosphere can also cause corrosion in the presence of moisture. This makes it easy to diagnose and prevent. Although the mechanical properties of the copper traces remain intact, there is a change in color. The increase in resistance can cause issues in circuit boards, as it prevents free flow of electrical current. Because of the reaction, copper turns into copper oxide with low electrical conductivity. A chemical reaction between the copper on the PCB and moisture/oxygen present in the atmosphere causes this type of corrosion. This is the most common form of corrosion, and is also known as uniform attack corrosion or atmospheric corrosion. There are different types of corrosion and understanding their nature helps in the diagnosis and prevention. Circuit boards are highly susceptible to corrosion as they contain a high amount of copper in each layer. Therefore, PCB manufacturers frequently cover the base metals like copper on the PCB with noble metals like gold to prevent corrosion. On the other hand, some alloys of copper, silver, gold, and graphite can resist corrosion indefinitely. Thin layers of tin, nickel, copper, and lead, all of which are present on the PCB surface, can be susceptible to corrosion. As the copper oxide flakes off, the copper track loses its volume, and its resistance increases which can cause performance issues. In the case of printed circuit boards with copper traces, corrosion result in the creation of copper oxide, which is a non-conductor of electricity. This paves the way for proper caring of the board, to allow them to work uninterrupted through the duration of their life.Ĭorrosion is the common name for the oxidation of metals and occurs when oxygen bonds with a metal. We recommend understanding the basic causes of PCB corrosion. Progressive corrosion can make the board work ineffectively, or even make it stop working altogether. Corrosion increases the resistance of the copper tracks on the surface of a circuit board. One of the major causes of failures is corrosion. Failure of electronic devices is a major concern anywhere in the world.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |