Types, Cleaning and Prevention to Avoid Corrosion PCB

Introduction

When you think of corrosion, one of the first things that probably comes to mind is rust – and you would be right. Corrosion can also lead to other problems, though, which makes it even more important to be aware of some of the different types of corrosion effects.

Brief Description of Corrosion PCB

Corrosion is the process by which a material loses its original properties due to a chemical reaction with its environment. Corrosion on a printed circuit board indicates that the copper has begun to erode and is being replaced by other materials such as carbon or oxygen.

The corrosion process may cause a number of problems with electronics, such as short-circuiting, reduced current capacity, and increased electrical resistance. This is most typically produced by oxidation (rusting), although there are other forms of corrosion generated by chemical interactions with components or other materials.

Corrosion PCB

Corrosion PCB

Why Does Corrosion Happen in a PCB?

PCBs are prone to corrosion because they are composed of a variety of components, including copper, which readily interacts with water.

Other elements that may induce corrosion in your printed circuit boards to include:

Electrochemical Migration

When a current is applied to a conductor, it creates an electric field. This electric field can cause electrons to flow from one terminal of the circuit to another. These electrons leave behind ions or charged particles. The ions are attracted to the surface of the conductor and stick to it, causing corrosion.

This process is called electrochemical migration, and it happens whenever there’s an electrolyte present (which is just a liquid that conducts electricity). The most common electrolyte is water, but other liquids like salt water can also be electrolytes.

Electrochemical Migration

Electrochemical Migration

Dust

Dust can cause corrosion by acting as an insulator between the copper and the plating, which will cause a loss of conductivity. This can lead to a static buildup on your PCB, which is bad for all kinds of reasons.

Moisture

Moisture infiltrates the metal of a printed circuit board, creating a condition conducive to corrosion. If the moisture is left unchecked and allowed to get into other parts of the circuit board, it can cause serious damage.

Moisture

Moisture

Humidity

The humidity in the air can cause the materials used in a printed circuit board to oxidize. This oxidation can be caused by small amounts of moisture that are present in the air, as well as by water droplets that have landed on the surface of the board.

Humidity

Humidity

Flux Residue

This is a byproduct of the soldering process and is left behind on the circuit board while it dries. this is usually made up of chemicals such as borax, ammonium chloride, and lead acetate. These chemicals erode the copper traces on a printed circuit board, causing them to corrode over time.

Flux Residue

Flux Residue

Types of Corrosion PCB

Corrosion is a major concern in the electronics industry, especially when you’re dealing with printed circuit boards. It’s important to understand the different types of corrosion that can occur on your circuit boards, and what measures you can take to prevent them.

Atmospheric

At the most basic level, corrosion is a chemical reaction between two substances. When a material combines with the oxygen in the air, atmospheric corrosion develops. This can be a concern for printed circuit boards since they are manufactured from copper, which is a great conductor of electricity and also prone to oxidation.

If there is moisture present, it may also react with the copper and cause corrosion. The result of these reactions is the formation of a greenish substance called Green Rust which slowly eats away at the printed circuit board.

Atmospheric Corrosion

Atmospheric Corrosion

Fretting

A form of electrochemical corrosion that occurs when two metal surfaces are in contact with each other, and one of the metals is subject to a corrosive environment.

The surfaces in contact are often two different metals such as copper and steel, or copper and aluminum. In this case, the steel or aluminum surface acts as an anode and corrodes at a faster rate than the copper surface. This causes an electrical current to flow from the copper to the steel or aluminum, resulting in the formation of copper oxide on the surface of the copper circuit board.

Fretting Corrosion

Fretting Corrosion

Galvanic

This can happen because of a wire or cable, where one end is connected to the positive terminal and the other end is connected to the negative terminal. The current will flow from one end to another, making it possible for one end of the wire or cable to be coated with anodic corrosion and the other side to be coated with cathodic corrosion.

Galvanic Corrosion

Galvanic Corrosion

Electrolytic

Electrolytic corrosion occurs when an ionized substance (electrolyte) is placed in contact with two electrodes—one positively charged and one negatively charged—and an electrical current passes through them. The presence of an electrolyte increases the rate at which electrochemical reactions occur; this means that the corrosion process happens faster than it would otherwise.

Electrolytic Corrosion

Electrolytic Corrosion

Localized

When there is a localized source of corrosion, it can lead to problems with the circuit. This usually happens with components that have been exposed to moisture.

The first sign of localized corrosion is that the component starts to tarnish and develop a green, brown, or red coating. This can cause it to look old, but more importantly, it can cause the circuit to fail.

Localized Corrosion

Localized Corrosion

Intergranular

Intergranular corrosion occurs when the metal is exposed to an electrolyte that can attack the metal at its grain boundaries. This type of corrosion is common in metals that have low melting points and high thermal conductivity.

The problem with intergranular corrosion is that it looks like other kinds of corrosion, so it can be tricky to tell if you have it. It usually shows up as tiny pits that are less than 1mm deep. These pits are also often covered with a white or grayish-green powdery substance. This powdery substance is actually an oxide—a layer of material that forms when metal rusts.

Intergranular Corrosion

Intergranular Corrosion

Electrolytic Dendrite

This happens when two or more different metals are in close proximity to each other, and an electrolyte (usually water) is present. The electrolyte can cause the metals to corrode at different rates, resulting in a series of tiny tree-like structures called “dendrites.”

Electrolytic Dendrite Corrosion

Electrolytic Dendrite Corrosion

Crevice

A type of corrosion that occurs when a small amount of liquid is trapped in a space between two metal surfaces. The liquid may be water or any other type of liquid, but it must be present and present in sufficient quantity to cause corrosion.

Crevice corrosion occurs most often when there is a small gap between two elements in a circuit board such as the leads of an integrated circuit (IC) or other components, with no barrier to prevent the entry of moisture.

Crevice Corrosion

Crevice Corrosion

Filiform

A type of corrosion occurs in printed circuit boards that are caused by moisture seeping into the board, where it forms a thin layer of rust on copper traces and vias. The rust spreads out from there, causing a “filiform” pattern.

Filliform Corrosion

Filiform Corrosion

Methods for Cleaning Corrosion PCB

Corrosion is one of the most common problems that can affect printed circuit boards. It is caused by a reaction between the copper and oxygen in the air, which results in the formation of a thin layer of corrosion on the surface of the board.

This layer can be removed using any one of several different methods, including:

By Compressed Air

Using compressed air to clean corrosion-printed circuit boards is a good option if you have access to a compressor, or if you can rent one. You’ll need to be able to blow air through the holes of your circuit board, so it’s best suited for small-scale cleaning.

You’ll also want to make sure that you’re using filtered compressed air, as any dust particles in it can clog up your board and make cleaning more difficult.

By Compressed Air

By Compressed Air

By Brush

Brushing is an easy way to remove corrosion from printed circuit boards without damaging any of the components on the board. It’s also inexpensive since all you need is a toothbrush and some water.

If you have a lot of PCBs that need cleaning, then it might be worth investing in a dedicated brush for this purpose only (and maybe even consider buying some replacement heads). But if you just have a few boards that need cleaning, then any old toothbrush should do just fine.

By Brush

By Brush

By Household Cleaning Solution

Make sure that you’re using a solution that’s safe for the material of your printed circuit board. For example, if it’s made of plastic, then you should only use a solution that’s safe for plastic. You also want to make sure that the solution isn’t too strong or concentrated—you want just enough so that it can effectively dissolve the corrosion without damaging your board.

To clean the corrosion off of your printed circuit board, simply soak it in your chosen cleaning solution for about 15 minutes. Then take it out and wipe away any remaining corrosion with a rag or paper towel.

By Deionized Water

This type of water is water that has been stripped of all ions, including sodium and chloride. This means that there’s no salt left in the water. This kind of water is perfect for cleaning corrosion off of printed circuit boards because it doesn’t leave behind any residue or get stuck in any cracks, which could cause further damage.

This water has a pH of 7 and contains no mineral ions, so it will not cause further corrosion when applied to your board. You can spray this water onto the board with an air compressor or other sprayer.

By Deionized Water

By Deionized Water

By Baking Soda

If you want to clean corrosion from a printed circuit board, try baking soda. This is alkaline that can aid in the removal of corrosion from the PCB’s surface. In addition, it will help neutralize any acid present in the corrosive solution.

By Towel

We recommend trying is using a towel to wipe away the corrosion. You can use a microfiber cloth or even just a regular old dishcloth to gently rub away any dirt or grime from around the area where the corrosion has occurred. Make sure not to rub too hard—you don’t want to scratch up your board!

By Towel

By Towel

By Oven

Another option is using an oven cleaner on your board. This method works well if there is only light corrosion on your boards and they aren’t too damaged from water damage or other problems like electrical shorts. The downside of this method is that it might take longer than other options due to requiring more time for drying before being able to use it again.

By Oven

By Oven

Ways Prevent Corrosion PCB

Prevention is better than cure. Here are some ways to prevent corrosion in your printed circuit boards:

Controlled Lamination Procedure

One of the best ways to prevent corrosion in printed circuit boards is to use a controlled lamination procedure. In this procedure, all of the layers of the board are laminated together at once, which creates an airtight seal between layers. The airtight seal prevents water from getting into the board and causing corrosion.

The controlled lamination procedure can be used for single-sided or double-sided boards. With single-sided boards, one side will have an adhesive on both sides so that it can be laminated with another layer of material. Double-sided boards have adhesive on just one side, so they can be laminated with either another layer of material or with themselves.

Appropriate Soldermask

To prevent corrosion in printed circuit boards, it’s important to use an appropriate solder mask.

A soldermask is a protective layer that covers the copper traces of a PCB and protects them from corrosion caused by the environment. It’s usually made using an epoxy material or lacquer-based paint.

Meshed Copper Planes

A meshed copper plane is a layer of copper that runs through the middle of a printed circuit board. This layer helps prevent oxidation on the surface of the board and also acts as a heat sink for dissipating heat away from components.

ESD Bags for Storage

An ESD bag is a specially designed storage container that prevents the build-up of electrostatic charge on your circuit boards. If a circuit board has an electric charge, it will attract other electrons, which can cause corrosion. An ESD bag can prevent this by blocking the flow of electrons, so they cannot build up on your circuit boards.

ESD Bags

ESD Bags

Micro-Encapsulation

When a printed circuit board (PCB) is manufactured, it is coated with a layer of varnish that protects the circuit from oxidation and other forms of corrosion. This protective layer is called a “coating” and can be made from different materials such as epoxy resin and silicone rubber.

However, this coating only lasts for about 10 years before it begins to wear off and become ineffective at protecting the PCB from damage. Micro-encapsulation provides an improved form of protection by applying several layers of protective coating on top of each other instead of just one single layer like traditional coatings.

Thermal Overmolding

It’s a process that uses heat and pressure to create a thin, flexible coating on the surface of your printed circuit boards. This process involves applying a thermoplastic material to the surface of a PCB. The plastic is then heated and molded around the PCB.

Conformal Coating

A type of coating that is used to protect the quality and integrity of printed circuit boards. Conformal coating is a thin film that goes over the surface of an object to seal it from moisture, corrosion, and other factors that can degrade its quality.

Conformal coatings are especially important for printed circuit boards because they allow them to maintain their function in a wide range of environments. They can be applied over both exposed and non-exposed areas and protect against damage from water, humidity, air pollution, temperature changes, or other factors.

Baking

This is a method of drying out the PCB board after it has been manufactured. It’s done by heating up the board and allowing it to sit at that temperature for a certain amount of time. This process removes any moisture that may be present on the board and helps prevent corrosion from occurring later on.

Surface Finishing

Surface finishing is an important part of the manufacturing process when it comes to printed circuit boards. It is necessary to ensure that the surface of your PCBs is free of any contamination which may cause corrosion. This process can also help you achieve better performance in your circuits by making them more resistant to heat, moisture, and other environmental factors.

These are common surface finish types used to avoid corrosion PCB:

Surface Finishing

Surface Finishing

Conclusion

It can be disappointing and troublesome to find corrosion on your PCB that not only diminishes the aesthetics of your work but also affects its functionality of it. Corrosion usually takes place after a while, depending on how you store your circuit boards or if you are giving them properly. For instance, if a PCB is left outside during the rain and is not protected, there is a possibility that it will undergo corrosion.

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