In our modern, technologically advanced society, it is common knowledge that water and electronic components do not get along very well together. When combined, these two components invariably produce a result that is fraught with significant difficulty. Although distilled water does not conduct electricity, water that has dissolved salts, chlorides, and sulfates is an excellent electrical conductor. Pure water does not conduct electricity. The water that is typically found in our immediate environment is not in its most unadulterated form.
When the various components of a circuit board are subjected to tap water, it might result in short-circuits or lower the efficiency of the circuit. Both of these outcomes can be undesirable. As a result, they require protection against moisture as well as corrosion. As a result, the first thing that must be done is to check and see if the fundamental circuitry of their device is resistant to water. The use of waterproof PCB is appropriate in this scenario. The following guide will look at what they are, how important they are, how they are used, and how manufacturers make them.
What Is a Waterproof PCBs?
Waterproof Printed circuit boards (PCBs) have a protective covering that makes them resistant to moisture as well as other environmental elements. Waterproof PCBs are also known as waterproof printed circuit boards. The coating is commonly composed of a resin-based material, and it covers the entirety of the circuit board as well as its individual components. This creates a barrier that prevents water, dust, and other contaminants from penetrating the board. This waterproofing technology can be used to both rigid and flexible circuit boards, offering increased safety for sensitive electronic components and electronics as a whole. The usage of waterproof printed circuit boards (PCBs) for vital components is common in a variety of industries and applications, including the medical, aerospace, and military sectors, as well as the industrial and consumer electronics sectors.
How to Waterproof Your PCB Boards?
Waterproof printed circuit boards (PCBs) are an absolute necessity for any electronic device that could potentially come into contact with water or moisture. It is possible to waterproof a printed circuit board (PCB) in a variety of methods, such as by employing water-resistant PCB substrates, sealing connectors, adding waterproof paint, and placing waterproof material on the topmost layer. Depending on the use of the PCBs and the degree of waterproofing that is necessary, each of these approaches can be utilized successfully with a distinct variety of PCBs.
Under any and all circumstances, it is best practice to keep moisture and water away from electronic devices by isolating them. However, in order to use electronic circuit boards in some locations where the amount of water present in the air is significantly higher, it is advisable to use waterproof PCBs. The PCBs that are utilized in marine applications are subjected to extremely high levels of moisture over the course of their lifetimes. Since of this, the usual PCBs were not successful there because they absorbed the water.
Apply Waterproof Material on Printed Circuit Board
This technique is utilized for the production of particularly specialized items, such as printed circuit boards (PCBs) for use in the control systems of vessels (ships, submarines, etc.). In this method, you can make the surface of the PCB board waterproof by adding a particular material to it, such as parylene C or parylene n.
Both parylene C and parylene N are, in point of fact, the same substance. Both of these materials are high-density polymers, and they are capable of being sliced into very thin layers. The majority of the time, they are in liquid form when we apply them to the PCB boards. After a predetermined amount of time has passed, they will begin to solidify and will eventually become watertight. The standard varnishes, such as epoxy resin, have a thickness that is significantly greater than that of Parylene C, which has a thickness of around 2 mils (0.05 mm). You have the option of using either parylene C or parylene n as the material for your PCB board if you require it to be water resistant.
Apply Waterproof Paint on the Printed Circuit Board
If you find out after the PCB production that you require a waterproof PCB or if you want to waterproof your DIE printed circuit board, you may do so by painting it with a waterproof paint. Alternatively, you can use a waterproof paint if you want to waterproof your PCB before producing it. The board receives an additional level of protection in addition to being simple to apply thanks to the waterproof paint.
This technique for protecting PCBs against moisture is both effective and economical at the same time. However, you should be careful about the quality of the paint, as there are many waterproofing paints on the market, but not all of them are of a high-quality and reliable.
Apply Waterproofing Material to Seal up the Connectors
You have the option of using waterproof materials to cover up the connectors on the printed circuit board (PCB) if you want to construct a waterproof PCB that is not being used for a specific purpose. Connectors’ primary function is to facilitate the joining of various components, including wires, terminals, and sensors, amongst others, to one another and to other components. When the connectors are being used, they will be brought into direct touch with water. In the event that they are not meticulously sealed up, the water will make its way onto your PCB board. In the event that it takes place, your electronic devices or PCBs would be readily destroyed.
Note:
When applying a conformal coating, it is necessary to examine and optimize the following four factors:
● The materials used for the conformal coating.
● The application method for conformal coatings.
● The procedure for curing and drying conformal coatings.
● The inspection procedure for conformal coatings.
Your optimal choice for each of these aspects will be determined by the production volume and lead times, the fixtures that are now available, the environment, the level of complexity of the PCB, and so on.
Benefits of Waterproof PCBs
The following is a list of some of the most important advantages offered by waterproof PCBAs:
Longer lifespan:These sorts of printed circuit boards (PCBs) typically have a longer lifespan than ordinary PCBs since they are subjected to more strict quality inspections and are waterproofed.
High durability: Waterproof PCBs can withstand high levels of water and dust. They have oxidation and corrosion resistance.
Excellent functionality: High-precision boards that can handle high transfer rates are typically found on waterproof printed circuit boards (PCBs). Therefore, they need to maintain the same level of functionality no matter what the weather is like. Again, they need additional testing to guarantee that they are of high quality and perform properly.
Comprehensive range of applications: For example, portable programs such as the ones on your mobile or smartphone can be used in regions with harsher weather.
The Limitations of Waterproof PCBs
The following are some of the key limitations of waterproof PCBs:
● They have a higher overall cost, both in terms of production and buying.
● Producing waterproof PCBs takes additional time. The application of conformal coatings as well as resin coatings is the primary cause of this issue. In addition to that, they demand extremely thorough testing.
Test a Waterproof PCB Methods
There are two methods that can be used to test whether or not PCBs are waterproof:
● Using another compound: By applying a varied mixture to the conformal coatings, you can test their application. For example, you can apply Epoxy to a conformal coating that does not contain Epoxy. The mixture will not adhere to the PCB if it has been evenly covered.
● Using an alcohol spray: In order to test for liquid conformal coatings, we make use of this technology. After spraying the alcohol spray, if droplets start to form, this indicates that the waterproof PCB you have has a conformal coating that is liquid-based.
● Using Manual or automated inspection: Using a lamp, an inspector can perform a manual check to ensure that the coating is watertight. Alternately, we may make use of a computerized scanning or optical instrument.
The only other way to test whether or not the PCB effectively waterproofs itself is to expose it to moisture. This method may carry some degree of danger. As a result, we strongly advise that you restrict your use of this method to the testing of prototype PCBs.
How Should the Waterproof Application on PCB Be Handled?
Dispensing
This method of application is by far the most popular approach utilized for painting PCB boards. The paints are initially held in a hopper before being pumped into a gun as part of this operation. With the use of a spray gun, the paint will be applied to the PCB board by spraying it on.
Manual Spray
This method is very similar to dispensing, but manual spray can be used in place of dispensing if you do not have access to a specialized painting machine or if you need to paint a wide variety of PCB boards that cannot be painted using the dispensing method. If you have the option, it is recommended that you utilize manual spray instead of the dispense method since manual spray enables you to paint with a high degree of precision and makes the surface of the PCB board smooth.
Dipping Process
The PCB board will be coated in this step by being dipped into the paint tank. It is a standard industry procedure. However, because PCB boards must have some thickness, it is not recommended that you use the dipping process when creating PCB boards and electronics. When you dip your PCB boards into the clear coat, the majority of the clear coat will adhere to the surface of the PCB board while the remainder will remain in the paint tank. This will result in an uneven clear coat PCB coating on the PCB board.
Conformal Coating of a Waterproof PCB : How to Remove
In order to make repairs or make modifications to an Epoxy PCB, it may be necessary to remove the conformal coating. You can accomplish this in a few different ways:
● Grinding (AKA Scraping): The PCB could be harmed using this technique. It entails manually scraping the PCB’s covering. It works best against polyurethane, parylene, and epoxy. Grinding, however, carries a risk because it could harm the PCB.
● Using Solvent: Waterproof coatings that are vulnerable to removal by solvents such as acetone compounds can be removed by these solvents.
● Micro-blasting: To remove the coating from the PCB, operators use a spray that combines compressed air and a soft abrasive. Epoxy and parylene resins are the most amenable to this technique.
● Peeling: A complex process in which an operator manually removes the coating from the PCB. Peeling often only works on hard silicone coatings.
● Applying concentrated heat: By applying heat, we are able to remove the majority of conformal coatings. However, there is a risk that this procedure will damage the PCB as well as the electronic components on it.
Is There a Solution Beyond Conformal Waterproof Coatings?
It is well known that the conformal waterproof coating is one of the most useful and well-liked materials that are utilized to protect PCB boards. It is a very thin, elastic, and protective material that, in order to make the PCB board waterproof, can be sprayed over it. PCBs can be shielded against harm in a variety of settings thanks to its application. However, despite their widespread use, conformal waterproof coatings have a few drawbacks that must be considered. Under some conditions, they cannot provide adequate protection for PCB boards because of their limitations. In general, there are two primary reasons that have led to this circumstance:
● Due to its low adhesive strength, the conformal waterproof coating cannot effectively prevent water from infiltrating the PCB board.
● The PCB board will be harmed in a wet environment or when the environment is extremely corrosive, even though the conformal waterproof coating can prevent water from getting into the PCB board.
In the past, PCB makers would safeguard their boards by only employing the usage of conformal waterproof coatings. They did not have any other solutions, nor did they find any other ways to solve this problem, thus they were at a loss. Because of this, they had to pay careful attention to the design of the PCB board and make use of specific PCB materials in order to ensure that the board was waterproof.
When to Use Waterproof Enclosure and Conformal Coating？
An enclosure is distinct from conformal coating. On the other hand, if you need to make your electronics waterproof, you will need to employ enclosures. Your electrical devices need to be shielded from both air and water, and the enclosure serves that purpose. It functions similarly to a tent in that it shields your electronics or PCBs from the elements, including water, air, corrosive gases, and other potentially damaging elements.
In order to ensure that the surface of a PCB board is waterproof, conformal waterproof coatings are often sprayed onto the board.
So Which One Do You Need?
● If you plan on making your own electronics or waterproofing circuit boards, you will without a doubt require conformal waterproof coatings in addition to enclosures. It is recommended that you use both of them together if the environment is too caustic or too damp to utilize either one of them alone. You may find that you need to make your electronic devices or PCB boards waterproof only in certain circumstances. In this particular scenario, conformal coatings can be used instead of enclosures. Protecting printed circuit boards (PCBs) against moisture in corrosive and damp conditions can be accomplished with the use of conformal coatings. When working in situations that are both wet and corrosive, it is strongly advised that you utilize conformal coatings to safeguard any electronics or PCB boards that you might have.
● It is not necessary to employ conformal waterproof coatings at all if you are constructing a waterproof PCB for a specific purpose. For instance, there is no requirement for these kinds of materials when building PCBs for the control system of a ship or submarine or any other type of vessel. This is because it is not permitted that water get into the control system, since this could result in the ship or submarine sinking.
There are a variety of methods available to waterproof your circuit boards or other electronic devices. You are free to pick one that best suits your requirements. It is recommended that you use a conformal coating first, and then enclosures, if you need to make your electronics or PCBs waterproof in a damp environment. This is because conformal coatings are more water resistant than enclosures. Your electrical components or PCBs will be properly protected with this method, not just from water but also from corrosion and other potentially damaging causes.
Temperature Changes’ Effects on Waterproof PCBs
Temperature shifts that are outside the parameters of the waterproof PCB could cause it to become damaged. As was just said, temperatures that are too high can cause the conformal coating layer to get damaged. If something like this were to occur, there would be no point in attempting to waterproof the area using this method. In addition, because of the conformal coating and the waterproofing enclosure, the extra heat that is generated within the circuit board will not be drained in an appropriate manner. This will cause the PCB to suffer on the electrical side and will shorten its lifespan. Therefore, prior to deciding on the conformal coating, it is necessary to take into account the suitable coating material and thickness, as well as to calculate the amount of heat that will be generated.
Are Waterproof PCBs Customizable by Your Company?
We can customize most waterproof PCBs during the manufacturing process. However, once we apply the waterproof coating, it becomes nearly hard to modify the PCB’s design, unless you use structural waterproofing to remove the encasing without causing any damage to it.
Conclusion
When it comes to excessive humidity and corrosion, a waterproof PCB is your best bet. The waterproof PCBs excel in environments with high humidity, making them ideal for marine and military use.
At present, enclosures and conformal coating are the main two ways of pcb waterproof.
The conformal coating process involves spraying a very thin layer of chemical compounds such as parylene, urethane, and acrylic on the topmost layer of the PCB in order to seal it. Waterproofing enclosures, on the other hand, are simply boxes composed of plastic or stainless steel. These enclosures serve as a barrier between the printed circuit boards (PCBs) and the outside environment, and they offer superior resistance to water compared to conformal coatings. If you want to more waterproof PCB detail, please contact us today!