Potting compounds and encapsulants for electronics and cable connections
We offer high quality products for potting and encapsulation of printed circuit boards and individual electronic components as well as for sealing and protecting electrical components and connections, e.g. cables. We provide products from Relicon and Wacker Chemie. These are polyurethane resins as well as RTV-1 and RTV-2 silicone rubbers.
Cast resins Relicon
Standard two-component polyurethane cast resin PUR33
Green colour. Hard. Developed for repairing cables and wires. Appropriate for many applications: potting, sealing, electrical insulation, casting of elements.
Elastic two-component polyurethane cast resin PUR771
Black colour. Developed for repairing cables and wires. Suitable for many applications – potting, sealing, electrical insulation, casting of elastic parts.
Encapsulants and sealants Wacker Chemie
The sealants and encapsulants produced by Wacker Chemie are silicone rubber, either one-component (RTV-1) or two-component (RTV-2), which cures at room temperature. Silicone rubber is characterised by its high temperature resistance, which is why it is sometimes called high-temperature silicone. A standard silicone sealant is resistant to temperatures up to 150°C in continuous operation, while a high-temperature silicone, i.e. a silicone with special additives, is resistant up to 250 – 275°C.
Silicone rubber RTV-1
RTV-1 silicone rubbers are one-part systems which cure at room temperature from air humidity. During curing process, they release small amounts of byproducts in the form of a vapour, usually with a characteristic odour. Depending on the type of vapour released, RTV-1 silicone rubbers are classified into three groups:
1. Acidic RTV-1 silicone rubbers (acetoxy), releasing acetic acid vapour
2. Alkaline RTV-1 silicone rubbers, releasing amine compounds
3. Neutral RTV-1 silicone rubbers, releasing either oxime compounds or alcohol vapour (alkoxy)
The release of byproduct during curing causes RTV-1 silicone rubbers to have shrinkage equal to the amount of byproduct released. The standard shrinkage of RTV-1 silicone rubber is between 3-5%.
RTV-1 silicone rubbers are characterized by very good adhesion to the substrate and comfort of use. However, the disadvantage is the rather long curing time (full curing usually takes approx. 12 h/mm), which depends on air humidity (min. 50%). For this reason RTV-1 silicone sealers are recommended for thin-film coatings (conformal coating).
Silicone rubber RTV-2
RTV-2 silicone rubbers are two-part formulations which cure at room or elevated temperature. They are divided into condensation-curing systems, characterised by a shrinkage of 1.5-2%, and addition-curing systems, which have a shrinkage of approx. 0.1%. Condensation-curing silicone rubbers are formulations where the cure speed can be varied within limits by adjusting the ratio of main component to curing agent. In general, addition-curing silicone rubbers tend to have better mechanical properties than condensation-curing silicone rubbers. The most common application for RTV-2 condensation-curing silicone rubbers is as a silicone sealant for electronics and electrical engineering. The curing of addition-curing silicone rubbers, on the other hand, is controlled both chemically with a catalyst (accelerating the reaction) and an inhibitor (retarding the reaction), as well as by increasing or decreasing the temperature from room temperature level, i.e. 23°C. Addition-curing silicone rubbers are most commonly used as a coating for electronics and as a molding compound for creating flexible reproduction molds or casting flexible insulation components.
A one-part, liquid silicone rubber. It is a solvent-free, neutral cure, low viscous and non-thixotropic silicone sealant which cures at room temperature under influence of atmospheric moisture. The formed transparent, highly elastic coating can be easily removed locally with a sharp tool, e.g. for repair or replacement of parts, and then reapplied.
A liquid, transparent silicone used for thin-film coating and sealing of electronic circuits. This one-part, solvent-based RTV-1 silicone rubber splits off an organic amine during curing. It cures at room or elevated temperature by reaction with air humidity to a flexible silicone coating.
Pourable, two-component, neutral silicone rubber, translucent in colour. The product has very low shrinkage when curing (addition-curing system). Due to its high elasticity, it is possible to remove the silicone locally for repair purposes and then reapply it later. Normally, the product has poor adhesion to other materials. Therefore, to increase the adhesion, a primer should be applied.