PCB Corrosion: Causes & How to Prevent It

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Apr 9, 2020|PCB Maintenance, Repair and Troubleshooting

PCB Corrosion is caused by many different factors, such as the following:

* Atmospheric Corrosion

* Localized Corrosion

* Galvanic Corrosion

* Electrolytic Corrosion

* Electrolytic Dendrite Formation

* Fretting Corrosion

* Intergranular Corrosion

Circuit board corrosion can be extremely harmful to printed circuit boards, and while there are many things that can cause it, there are also several ways to clean it using conventional household products like baking soda and compressed air. 

Preventative methods can also be put into place to ensure that future PCB corrosion doesn’t take place. 

What Causes PCB Corrosion?

Circuit board corrosion can be harmful to the point of completely destroying a PCB, rendering it useless. There are several causes of this corrosion, which is the process of oxidation that occurs when oxygen bonds with metal and produces rust and flaking.

Atmospheric Corrosion

Atmospheric corrosion is the most common type of PCB corrosion that involves metal becoming exposed to moisture, which, in turn, exposes it to oxygen. These elements combined lead to a reaction where the metal ions bond with the oxygen atoms to form an oxide. 

Atmospheric corrosion happens mainly with copper components. While copper will retain its mechanical properties even with corrosion, it will not retain its electrical conductivity. 

Localized Corrosion

Localized corrosion is similar to any kind of general corrosion, except that it mainly affects a limited or small area. This kind of corrosion can include filiform corrosion, crevice corrosion, and pitting corrosion. 

Galvanic Corrosion

This type of corrosion happens at the site of various metals and an electrolyte, where the more resistant metal corrodes faster than the base metal that it is touching.

Electrolytic Corrosion

Electrolytic corrosion occurs when touching traces take on dendrite growth. This growth happens when contaminated ionic moisture gets into the electrical voltage between the two traces. The result is metal slivers that cause a short circuit. 

Electrolytic Dendrite Formation

Electrolytic dendrite formation is what happens when there is ionic contamination in moisture. This deformation causes any adjacent copper traces with different voltages to grow metal slivers, which will ultimately cause shorts between traces. 

Fretting Corrosion

Fretting is the result of the continual closing of solder-plated switches. The motion creates a wiping action, which eventually removes the surface oxide layer. When this happens, the layer beneath it oxidizes and builds excessive rust, which prevents the operation of the switch. 

Intergranular Corrosion

This final type of corrosion involves the presence of chemicals on the grain boundary of a copper trace and happens because grain boundaries have higher levels of impurities that are more susceptible to corrosion. 

How to Clean Corrosion from PCB?

Over time, your PCB can accumulate more than just corrosion. Dirt, dust, and all kinds of grime can easily find its way into your electronic devices. Cleaning them can help prevent corrosion. But, if you have detected that your PCB already has corrosion, you can learn how to clean corrosion and use the following methods to avoid permanent damage. 

Using Compressed Air

Compressed air is a fairly common tool used in electronics cleaning. You can use compressed air by releasing short bursts to the inside of ventilation ports. This type of cleaning is recommended for routine electronic care, so if you’re dealing with corrosion, you will want to open up your electronics and hit it right at the source. 

Using Baking Soda

Baking soda is a highly effective ingredient used to clean corrosion from PCBs. Not only that, but it’s likely that you already have baking soda in your kitchen cabinet. Because baking soda is mildly abrasive, you can use it to scrub off corrosion and residue that won’t release with compressed air. Try using it with a gentle brush and distilled water. 

Using Distilled Water

Speaking of distilled water, this product is also a great way to safely and easily remove corrosion from a circuit board. In its purest form, distilled water will not degrade or ruin your electronic devices. It’s also a terrible conductor, so there’s no cause for worry. 

Using Household Cleaners

Any household cleaner is a good solution to PCB corrosion, but only if it’s phosphate-free. Phosphates are effective in protecting against corrosion, but it’s a strong source of pollution in American lakes across the country. But there are so many phosphate-free cleansers that will work just as well. There are also specially made PCB corrosion cleaners on the market as well. 

Using a Brush

A brush can be a super helpful tool when you’re cleaning your circuit boards, as it can help you get in between all of the tiny components. It’s crucial that you choose a brush with soft bristles. Size also plays a factor, as you need to be able to reach all the smallest spaces.

Most people like to go with a toothbrush or a paintbrush. They are sturdy and gentle, and most people already own at least one of them. 

Lint-free microfiber cloths are also good tools to have on hand to rub down and dry off your circuit board after you clean it. 

How Do You Prevent Corrosion on a Circuit Board?

Different metals have varying levels of corrosion risk. While they can all corrode eventually, copper and other base metals corrode much easier and faster than noble metals and some alloys. The latter of these are more expensive, so many professionals will stick to the more common metals, making it necessary to know how to prevent corrosion on PCBs and not harm their circuit boards. 

One simple way to prevent corrosion on a circuit board is by placing a coating over the exposed copper areas. There are many different types of coatings, including epoxy coatings, aerosol spray coatings, and solder masks. 

You should also do your best to avoid humidity surrounding your PCBs. Try to keep them in an environment that isn’t affected by humidity. You can use a humidifier in the same room to help with this. But knowing how to stop corrosion on PCBs is the first step to success. 

Conclusion

Corrosion on a circuit board is something that is naturally bound to occur at some point or another during the life of your electronic devices. While we can’t necessarily avoid it altogether, we can take steps to elongate the life of our electronics by preventing corrosion and treating it properly. Learning how to clean a circuit board of corrosion is easy, but it’s essential.