One- and two-component potting compounds are used very frequently. With two-component potting compounds, resin and hardener are mixed in a specific ratio using appropriate machinery and, as standard, poured into the cavity via a static mixing tube. Thus, this cold potting is a non-molding process and requires a housing into which the potting compound is poured.
Potting offers many advantages: Not only does it provide excellent electrical insulation, high heat dissipation, and vibration and shock reduction, but it also offers resistance to chemicals, moisture, thermal shock, and cycling, protects the electronics from dust and moisture, and possesses flame-retardant properties.
 
Depending on specific requirements, epoxy, polyurethane, and silicone resins are typically used. They all differ in terms of their properties (Table 1). 

With conformal coating, printed circuit boards are coated either completely or selectively. In the case of selective coating, only the necessary areas of the printed circuit board are covered with a protective layer. Generally, a distinction is made between two types of coating: Thin-film coating, with its fast curing time and optimized viscosity, ensures high cost-effectiveness in manufacturing processes. In contrast, thick-film coating provides particularly high edge and surface protection, safeguarding electronic assemblies especially against extreme humidity. In both cases, conformal coatings build up layer thicknesses of only 30–2000 µm after drying. This means the electronic assembly can still be installed in tight spaces. 

 Due to the varying viscosities of the protective coatings and their resulting differences in flow behavior, the DAM & FILL principle is frequently applied to assembled electronic assemblies. Here, a thixotropic protective coating is used to form a “dam” around components that must not be encapsulated, such as connectors. The remaining components are then coated with a low-viscosity conformal coating (“Fill”).Various polymer materials

are used for conformal coating. Users can choose between silicone-based and UV-curing products, among others. The former are ideally suited for harsh operating conditions, such as in aerospace or offshore applications, due to their wide temperature range from -40°C to +200°C. The latter consist of acrylates and polyurethanes or hybrids of both materials. They are characterized primarily by the fact that they cure very quickly through UV initiation and offer excellent thermal shock resistance.

The applications for conformal coatings are diverse and range from the automotive sector to rail technology, sensor technology, industrial electronics, medical technology, as well as the aforementioned offshore wind power and aerospace technology.

Hot-melt molding is a specialized form of encapsulation. In this process, the assembly is coated with a material in a single step, creating a housing structure while simultaneously protecting the assembly. The electronics remain undamaged because the low-viscosity thermoplastics have a low processing temperature and are processed at significantly lower injection pressure than in standard plastic injection molding. This component protection is achieved while allowing the thermoplastics to cure quickly, making the process cost-effective.

Low-pressure injection molding thus enables even sensitive components such as contacts, sensors, printed circuit boards, and coils to be environmentally friendly encapsulated, bonded, or sealed to IP68 standards, thereby protecting them even from the most severe conditions.

One industry heavily affected by external influences is agriculture, for example. Here, machinery is subjected to varying weather conditions on a daily basis. Hot-melt molding is perfectly suited for protecting their electronics: It provides reliable, long-lasting protection against moisture, temperature fluctuations, corrosion, and vibrations. 

Extreme temperatures, dirt, and moisture, as well as chemical or mechanical stress: With the right component protection method, electronics are shielded from virtually any external influence. However, one aspect must be taken into account: Encapsulation is only possible if the functionality of the installed components is not compromised by the materials used. This also requires a potting-compatible connection solution—ruling out the use of standard PCB connectors. The reason for this is the typically two-part spring-blade contact technology, where the potting compound can penetrate the vulnerable mating area and thus interfere with the contact.

With conventional connectors, the contact area must therefore be sealed using a dam-and-fill method prior to potting to avoid any risk of interference from the potting compound (Fig. 2). The concern here is that the potting compound in the contact area could, on the one hand, impair the contact points and thus interrupt signal transmission. On the other hand, it would inhibit the relaxation properties of the spring.

To enable potting while still ensuring the required reliability, it is recommended to choose a one-piece connection solution—that is, a connector that does not require a conventional mating area. With such a one-piece connector, it is impossible for the potting compound to penetrate the contact area.