Corrosion is a major enemy of printed circuit boards. Circuit boards that are sufficiently corroded cannot work. Furthermore, be sure that the steady advancement of corrosion must happen. However, the question now is why printed circuit boards corrode. You may also be wondering what causes PCB corrosion.
In this article, we will explain what PCB corrosion is, the types, and the ways of getting rid of them, and measures you should take to prevent them. Please read on as we give more explanation concerning the topic.
What Does PCB Corrosion Mean?
Anytime, oxygen forms a bond with any metal surface, oxidation takes place. This could lead to rust and add to flakes of metal surfaces that break away. Due to the fact that pcb pads and pcb traces are manufactured from metals like copper, there is always a risk of corrosion.
Note that different metals corrode at different rates. There are metals that corrode immediately they get some exposure to oxygen, while some others may not even corrode in any way. High corrosion metals include silver, gold, copper-metal alloy, and graphite.
Also, metals that will most likely suffer from serious or severe corrosion include copper, lead, plated nickel, and plated tin.
What Causes PCB Corrosion?
Corrosion could be caused by different things, which includes capacitors, leaking batteries, weather damage and water damage. No matter the quality of corrosion on the circuit board, it could cause it not to function or work properly. Furthermore, it may even cause the components to experience more damage. Over time, corrosion can become worse and in the end can cause or lead to irreversible damage.
What are the Forms and Types of Corrosion?
With respect to the root of the parts rusting, the different forms of corrosion include
- General attack corrosion
- Galvanic corrosion
- Localized corrosion
- Intergranular corrosion
- Electrolytic dendrite corrosion
- Fretting corrosion
- De-alloying corrosion
- High-temperature corrosion
- Environmental cracking corrosion
- Flow-accelerated corrosion
The general attack type is the most significant form and it works on bigger surfaces. For localized corrosion, it affects just a small portion. In addition, galvanic corrosion takes place when two metals start corroding as a result of corrosive electrolytes.
The metal present in PCBs (printed circuit boards) can experience corrosion in different ways. These include:
Galvanic
This galvanic corrosion occurs or takes place when different metals come in contact with an electrolyte. When galvanic corrosion occurs, metals that are more resistant will corrode much faster compared to the baser metal that it forms a contact with. Therefore, whenever tin comes in contact with gold, for instance, the gold corrodes faster than expected.
Atmospheric
This corrosion type is known as the most standard. Here, metal gets exposure to moisture containing oxygen. This causes a reaction whereby there is a bond formed between the oxygen atoms and the metal atoms, creating an oxide.
It is very easy and ensures that copper experiences atmospheric corrosion. This isn’t an issue for copper plumbing. This is due to the fact that corroded copper retains or hold on to its mechanical properties. However, it fails to keep its electrical conductivity, thereby making circuit boards have a huge problem.
Fretting
When there is fretting corrosion, when the solder-plated switches close, it creates some wiping action, which helps in the removal of the surface oxide layer. This allows or makes it possible for the layer underneath to oxidize. This then leads to excessive rust building up and preventing the activation of the switch.
Electrolyte
For this metal degradation, the adjacent traces see a dendrite growth anytime the electrical voltage formed between them is infected by contaminated moisture. This creates metal slivers that cause short circuits.
Ways of Cleaning Corrosion from Circuit Boards
If the printed circuit board gets some corrosion as a result of water damage or through a different source, then you may repair it just by cleaning it.
To clean a circuit board, you will need daily household items which any company can afford. The issue here is that only individuals having the necessary knowledge of PCB electronics should make attempts to clean a PCB.
This process deals with the disassembling of the board and making sure that no damage comes to the components. Furthermore, when the PCB is separated from the electronics, keep a distance from the water and then disconnect your device.
To clean a printed circuit board (PCB), you can use a whole lot of different cleaning tools. However, some items function well for getting rid of corrosion. These materials are useful for cleaning or to clean a circuit board corrosion.
What are the Materials Useful for Cleaning Circuit Board Corrosion?
Distilled water
With the use of water for cleaning or to clean a circuit board, ensure that there are no contaminants in it. The ions that are present in the regular water feature conductive properties, which degrade electronics. However, distilled water features no ions or contaminants, which can lead to damage.
Baking Soda
Note that the abrasive and alkalinity qualities of the baking soda ensure it is a perfect choice for all corroded printed circuit boards (PCBs). Baking soda helps in clearing and neutralizing corroded areas preventing damage.
Soft-bristle thin brush
If there is no specialized PCB cleaning tool for your PCB (printed circuit board), you can make use of a paintbrush or toothbrush. This also works. Brushes having soft bristles will prevent a scratch coming to the delicate components of the board.
Household cleaner
Household cleaners that are phosphate free can effectively get rid of corrosion and dirt. Phosphates offer some protection for PCBs (printed circuit boards) from corroding. However, they can cause water pollution.
Compressed Air
Now, compressed air is a method that is non-disruptive in clearing accumulated dust within electronics and on surfaces. This method helps in blowing air into the gadget via the device’s open spaces. Furthermore, if there are small spaces, be careful when opening the equipment and then clean the circuit board carefully using the compressed air.
Oven
Using your usual household oven helps in drying a printed circuit board thoroughly when using indirect heat. Make sure that you switch off the oven first, before you place the circuit board inside it.
Lint-free Towel
Clothes that are manufactured from microfiber as well as other fabrics that are lint-free, aid the speed up of the process of drying without leaving out any particles.
How to Use Baking Soda for Cleaning Printed Circuit Boards (PCBs)
These materials above help in restoring the PCB’s corroded areas. Work with these steps and use baking soda importantly so as to clean corrosion from your circuit boards.
Record the configuration and layout of the PCB. Make sure you capture all the details with pictures or notes. This will help you when reassembling the board after you are done cleaning it.
Remove or disassemble the chips and cables of the PCB. With this step, you will be able to access all the corroded parts of the circuit board.
Clean making use of distilled water and baking soda. Combine a part of the baking soda with about 2-4 parts of water till it turns into a thick paste. Next, make use of the brush in scrubbing the cleaning solution in all the corroded areas. Next, allow the circuit board to dry for about 20 – 30 minutes. You can then use additional distilled water for rinsing.
Make use of household cleaner to do another pass. Ensure that you use the cleaner to spray all the corroded parts. After this, make use of a clean brush for your scrubbing once again. Lastly, make use of your lint-free towel in patting the circuit board dry.
Use your oven to dry your PCB. Set it at 170 degrees and once it has completed the preheating, turn it off properly. Next, place your circuit board into the oven and allow the heat to dry the remaining moisture.
Get the board reassembled and tested. Place the components together and then check the functions of the PCB once again. Make use of an eraser to remove the leftover corrosion if you discover that the circuit board is still not working.
What are the Effective Methods for Removing PCB Corrosion?
Two ways exist for cleaning corroded circuit boards. These include making use of a solution that has been mixed with baking soda, alcohol, and water. The other is making use of a special cleaning spray for circuit boards.
Below are some other methods.
Always make sure that you first of all remove the power source and batteries of the device. This prevents short circuits. It also prevents possible injuries. Note that when doing this, you may expose some other elements of your device to corrosion. Therefore, make sure that you do this very carefully.
You can easily find corrosion when you see a greenish or white substance looking and feeling crusty. The common places you should check are battery connectors, charging ports, connectors for SIM cards, as well as other mechanisms that will permit the connection of wired accessories onto the device.
Make use of Q-Tips or cotton swaps. You can also use water, baking soda, and isopropyl alcohol to clean up the corrosion. Vinegar is also useful. Apply this mixed solution onto that affected area. You can then wipe it back & forth to ensure that the corrosion disappears. This solution can also be applied onto the corroded part and then allowed to sit for long periods before you wipe it off.
Make use of the soft cloth or cool setting of a hair dryer to dry up the device. Never make use of heat to achieve this. Before you get the device back on or replace the batteries, ensure that you have dried the circuit board completely
Replace any damaged battery with a new one. Also, ensure you recycle the old one properly. Don’t dispose of them with any trash. This is because it can cause damage to your environment.
Ways of Preventing Corrosion on a PCB
Now, the question is, what ways can you prevent corrosion from coming to the PCB? You cannot avoid corrosion for forever, however delaying it is possible beyond the circuit board’s expected life. However, what are the steps necessary to achieve this?
The major goal when you are preventing PCB corrosion must be to prevent ionic contamination. When you expose components of circuit board to moisture, the ionic contamination is known as the major cause of corrosion in printed circuit boards. The first ever priority has to be to ensure that the pcbs as well as its components stay dry and clean.
Also, it is very important that this priority is kept in mind during the manufacturing of PCBs. Fabricators have to avoid getting liquids and fingerprinted on the printed circuit board and ensure that the boards are manufactured in a dry and clean environment. Also, designers have to take care and prevent moisture from beading up on the exposed conductors.
Also, when designing printed circuit boards to be used in applications that will most likely expose them to more liquid contaminants like industrial environments, agricultural industry, and automotive industry, you have to take some important steps in protecting your circuit boards from any environmental hazards that will likely happen.
Ensuring that the PCBs are kept dry and clean enough to prevent or ward off corrosion is easy. You only need little attention and care. However, taking any of these preventive steps doesn’t mean that corrosion will come to your PCBs. But the fact is that this reduces the possibility of corrosion happening and it is worth the care and effort.
Conclusion
You can learn more about ways by which you can prevent corrosion from coming to your printed circuit boards. For some reliable information to learn how Rayming PCB & Assembly ensures that their printed circuit boards resists corrosion, or you wish to learn other strict quality assurance methods we adhere to, please contact Rayming PCB today.
