Corrosion is one of the major enemies of printed circuit boards.Everything from motor vehicles to satellites, to printed circuit boards are affected by corrosion. Regardless of location or industry corrosion will prove to be a problem for anything made of certain metals. Corrosion occurs during oxidation, when oxygen and metal bond with each other, producing rust which causes the metal to lose its chemical properties. Printed circuit boards are composed mostly of metal and are naturally exposed to oxygen. Most printed circuit boards will corrode over time. PCBA King works diligently to assist our clients in keeping their boards rust free and functioning at high levels for as long as possible.
There are four common types of PCB corrosion: Atmospheric, Fretting, Galvanic, and Electrolytic.
- Atmospheric corrosion is the most common occurrence. Exposure to moisture causes metal ions to bind with oxygen atoms. Copper is highly susceptible to atmospheric corrosion due to its chemical structure and creates problems for conductivity.
- Fretting corrosion is a result of surface oxide layers being removed by the action of closing solder-plated switches which makes the layer beneath oxidize.
- Galvanic corrosion is caused by electrolytes being present between two different metals. For example, when gold is in contact with tin in the presence of an electrolyte the gold will corrode faster than usual.
- Electrolytic corrosion occurs when there is metal degradation. Metal degradation is the process of metal slivers being created by traces that experience dendrite growth. This generally happens when ionic contaminated moisture infects the electrical voltage between the traces. Metal slivers most often result in short circuits.
Unfortunately it is impossible to avoid corrosion entirely, but you can extend the life of your printed circuit board. Printed circuit board components being exposed to moisture with ionic contamination is one of the most common causes of corrosion in PCBs. Consider sealing enclosures and/or regular maintenance to ensure that your board stays clean and dry.
- HASL uses a corrosive flux to prepare the surface, which will not help corrosion susceptibility. Gold does not react with oxygen, which means it will not rust or corrode over time.
- Gold Immersion (ENIG) will protect your printed circuit boards surface. Gold Immersion (ENIG) also makes for a higher quality finish and look.
Keeping printed circuit boards corrosion free entails a combination of surface finish, enclosures and conformal coating and simply keeping boards clean and dry. Taking these steps can’t guarantee that your board will never be affected by corrosion but will always extend the life of your board.
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