What is potting in electronic assembly?
Electronic components are delicate, and given that some parts are reserved for use in rough environments, manufacturers must find a way to protect them.
But are all electronic enclosure designs suited to potting, or does it require some sophisticated procedures?
As our guest today, you probably know something about potting or want to learn everything from scratch.
Either way, we got you covered, so without further ado, let’s get right into it.
What is Electronic Potting?
The potting process keeps moisture and harmful gases off the electronic assembly parts.
Some will refer to it as the embedment process primarily because it encases the components in a shell or box-like structure.
Additionally, the potting media protects the sensitive components from corrosive agents and cushions them from shocks.
It can be the outer cover of an electronic assembly or an inner enclosure within a larger box.
Conformal Coatings vs. Potting Compounds
Flexible robotic conformal coating and dispensing system.
A conformal coating plays the same protective role as a potting material.
Nonetheless, the layer is unique in structure. Potting application involves encasing the finished component.
Conversely, a conformal coating is a nonconductive material with dielectric properties on an electronic circuit board.
Conformal Coatings and Potting Compounds: Similarities
- The two share a common material in organic polymers. In their absence, all external factors, such as shock, corrosion, and dust, would bombard the circuit board. Hence, they create a ‘wall’ that shields the components ensuring lengthy and optimal operation of the device.
- They also boost the performance of internal components by preventing overheating and PCB parts failure. They are, therefore, a barrier that, if absent, would lead to frequent electronic device breakdowns.
Best Scenarios to Use Potting
A Complex PCB.
The best time to use the wide range of potting materials is when the aim is to curtail the impact of vibrations during device use.
It is ideal for high-intensive device applications without wearing off, making it also fit for temperature resistance applications.
In addition to abrasion protection, other ideal situations include:
- It provides protection solutions when the manufacturer wants to shield the inner components from tampering. Dark-colored potting compounds also guarantee obscurity inside the protected parts’ chamber.
- Also, it is ideal when a device’s overall weight change after adding the material is insignificant. But when you’re looking to maintain the circuit board’s weight or width, then conformal coatings would be a better option.
Best Scenarios to Use Conformal Coating
A conformal coating on PCB.
You can never go wrong with conformal coatings when working on small form factor components such as mobile devices where the weight and thickness of the PCB matter a lot.
They provide an immense level of protection while also ensuring that the boards retain their designated thicknesses.
For instance, Types AR, ER, and UR conformal coatings represent Acrylic Resin, Epoxy Resin, and Polyurethane Resin, respectively.
These are ideal for boards with a thickness between 0.00118 and 0.00512 inches, respectively.
Other conformal coatings for thicker boards include silicone resin and Parylene Resin.
Potting And Encapsulation: Pros And Cons
Robot holding glue syringe Injection on the phone.
Here is a comparison of potting to conformal coatings by first looking at the upsides and downsides of the former.
Pros
- Many manufacturers will go for this method primarily because it’s easy to apply on circuit boards and more economical. The resilience of the encapsulation, even under high-temperature environments, is also a reason the technique is widely popular.
- Also, it is the ultimate abrasion resistance measure for electronics that operate in high vibrations. It guarantees 100% abrasion resistance, mainly if applied effectively.
- Thirdly, circuit board assembly factories with high turnaround times prefer this method as it’s arguably the fastest.
- An art electronics potting facility will also produce materials that can withstand all moisture exposure conditions with utmost resilience.
Cons
- Despite the high turnaround times when working with potting, this popular choice renders circuit boards quite hard to work on. Expelling the layers means exposing the circuit assemblies to destruction and harsh elements.
- It is also a multistep process which makes it quite complex to perform.
- Thirdly, the inspection process of dark potted PCBs is quite a hassle, and the electrical potting compounds can lead to unwanted increases in the circuit board and device weight.
Conformal Coating: Pros And Cons
A PCB conformal coating.
Pros
- Conformal coatings are the best bet in scenarios where we want to realize the visibility of the device parts and the circuit board.
- Also, the weight of the electronic device remains constant even after applying a conformal coating.
- If you are looking for flexibility in PCBs, this is the best protection method, and it is also cheaper to apply than conventional potting.
- Finally, they eliminate the essence of having complex and delicate enclosures like in the case of potting.
Cons
- The method doesn’t guarantee total protection of the inside materials, especially under challenging conditions.
- Coatings are also less durable than most conductive potting compounds.
Which Is Better To Protect My PCB?
A PCB enclosure.
To answer this question best, the primary consideration should be the product requirements you want to achieve.
Potting is ideal when building components where durability is a concern.
On the other hand, it introduces an increase in weight which can be problematic in circuit boards that operate under confined spaces.
But the mechanical strength of conformal coatings cannot match that of potting compounds.
The bottom line of this is that you have to make a tradeoff between durability and weight.
Which are the Best Potting Compounds?
The table below highlights the common compounds we use for potting and their standout features and ideal use conditions.
| Electrical Potting Compound | Properties |
| Urethane compounds | Its standout feature is high flexibility making it easy to work with most common electronic substrate components. Also, it has excellent abrasion resistance, ensuring the internal components are always safe. |
| Epoxy compounds | These are the ultimate go-to potting compounds when excellent adhesion is necessary. Also, like urethane materials, this compound has excellent tensile strength and is equally flexible. |
| Silicone compounds | They are most popular for their extensive temperature-of-use range. Also, they barely exert pressure/stress on PCB parts, but this feature makes them pricey. |
Selection Considerations for the Ideal Potting Compounds for Your Project
Illustrating viscosity.
Pay attention to these main aspects when choosing a potting material.
Hardness
If you aim to realize resistance to weather elements and IP protection, then you should opt for hard-potting compounds.
The most ideal one here is silicon, renowned for its extreme hardness but still flexible, making it quite friendly.
Viscosity
Low-viscosity compounds are easy to use and are the industry standard, although you can still encounter situations that demand high-viscous potting materials.
Therefore, depending on your scenario, you should always choose the best.
Color
This is a significant aspect of potting, as dark materials significantly hinder visibility. Always use light-colored potting when the work is for a lighting application, such as LEDs.
Thermal Conductivity
Choosing a potting compound with top-notch thermal conductivity makes all the sense.
Almost all PCBs will emit heat during use, and a highly conductive material eases the dissipation of the temperatures.
Factors to Consider When Potting an Electronic Assembly
There’s no ultimate potting method and procedure, as each manufacturer has unique ways.
But there are some critical aspects you need to get right for an efficient encapsulation.
- First, melt the compound at high temperatures to improve its viscous flow. But be careful not to heat it high and above the manufacturer’s requirements when performing this step.
- Also, is the resin-to-hardener ratio proper? Always balance hardness and flexibility, as both are equally significant.
- Make a hardener resin mixture and apply it at the appropriate dispense weight.
Applications of Electronic Potting
- It helps cushion electronic components in automotive parts such as common-use vehicles and forklifts from damage.
- Also, it is the ultimate protector of outdoor electronic parts such as street lights and sensors from weather damage.
Outdoor lights.
- Lastly, it protects any electronic part that requires shielding from harsh operating conditions.
Summary
Electronics manufacturers have over the ages evolved as the use of electronics in any field proliferates.
Thanks to circuit board improvements such as potting, we have devices that can withstand harsh surroundings with a breach of their internal parts integrity.
As technology advances, we progress further toward more mobile devices.
Hence, we are set to witness further developments in cushioning measures, such as improved potting mechanisms.