Encapsulation of Electronics

Why?
When working with electronics, you often deal with sensitive materials and components. It doesn't take much for a small sensor or diode to fail in performing its intended task. Therefore, it can be a good idea to encapsulate either the entire circuit board or certain components that need protection. Encapsulation can protect the electronics from the surrounding environment – wind and weather, shocks and impacts, fungus, moisture, dust, etc. A good encapsulation ensures that components last longer and do not short-circuit.
Also, in the growing LED industry, transparent/clear encapsulation adhesives are used to protect components. The adhesive protects components against moisture, vibrations, mechanical stress, and high and low temperatures.

Coating or potting?
There are several ways to protect your electronics. Two examples are coating and potting.

A coating is a thin film sprayed over the object to protect against contaminants such as moisture, dust, chemicals, etc. Potting, on the other hand, is when you place your object in a small box or enclosure and then cover it with adhesive so that the object becomes encapsulated and the box/enclosure becomes part of the finished product. The reason to use potting instead of coating may be that the circuit board must withstand shocks of a certain strength.

Sometimes it can be advantageous to use the so-called 'dam and fill' method. For example, if you have a circuit board where only a single or few components need protection, there is no reason to use excessive adhesive for encapsulation. Here you start by building a ‘dam’ around the component, then fill it with the chosen encapsulation adhesive. It goes without saying that the adhesive used to surround the component must first be very high viscosity so it does not flow out. Then you can fill the dam with adhesive of a viscosity suitable for the object. This method is economically advantageous when only certain components on, for example, a circuit board need protection through encapsulation, and with the right dosing equipment, it is not very time-consuming.

Adhesives for encapsulation
There are several options when choosing the adhesive or molding compound to protect your electronics. A 2-component polyurethane-based adhesive, for example, has many advantages. It is a durable adhesive that provides optimal protection against moisture. It generally has good chemical, mechanical, and dielectric properties and adheres well to most materials. They are usually available in black or transparent. When using adhesive for encapsulation of electronics, transparent adhesive can sometimes be advantageous. For example, when dealing with an LED or sensor intended to detect and respond to movement. Polyurethane-based adhesives also come in different hardness levels. You can get a quite flexible adhesive or one so hard that you can sand it. Likewise, it is available in almost all viscosities. Often, a relatively low-viscosity adhesive that self-levels fairly quickly is desired for electronics encapsulation. The only immediate drawback is the relatively low temperature resistance of polyurethane adhesives. If your object will be exposed to temperatures above approx. 100°C, polyurethane is not suitable.

If encapsulation that withstands higher temperatures than polyurethane adhesives is needed, you can use a 2-component epoxy adhesive. This adhesive has a heat resistance of up to approx. 180°C and protects well against moisture, dust, and chemicals. Here too, transparent adhesives are available, as well as many different viscosities. However, be aware of the hardness, as epoxy adhesives are quite inflexible with a high Shore hardness. They are also difficult to remove if that need arises.

Here you find a list of products very suitable for encapsulation/potting of electronics

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