Bectron® PK 4340 is a one-component resin system which cures to form a soft polyurethane duroplastic. It comprises a liquid polyol system with a dispersed solid encapsulated polyisocyanate and a pigment combination selected to provide controlled rheology including excellent thixotropic properties. Heating the resin releases the encapsulated polyiso- cyanate resulting in a polyaddition reaction to give a resistant duroplastic cured material.
In contrast to the usual 2 component resin systems Bectron® PK 4340 is ready to use and distinguished by excellent properties and especially good environ- mental compatibility.
APPLICATIONS
- The cured Bectron® PK 4340 is a soft duroplastic suitable for vibration protection of delicate compo- nents.
- Bectron® PK 4340 is therefore well suited for the partial or selective coating of SMD and other compo- nents groups on printed circuit boards and ceramic substrates. The rapid increase of viscosity at low shear allows small areas of components to be pro- tected individually.
- Bectron® PK 4340 can be applied as a dam around an area requiring thicker coating to be filled by a low- er viscosity grade such as PK 4342.
Properties of components as supplied
Property | Condition | Value | Unit |
Viscosity, DIN 53019 | D=15 s-1, 23°C | 9.500 ± 1.500 | mPas |
Density, DIN EN ISO 2811-2 | 23°C | 1,23 ± 0,02 | g/cm³ |
Shelf life | 23°C | 6 | months |
Pot-life, gel-time, curing conditions
Property | Value | Value | Unit |
Temperature | 80 | 90 | °C |
Gel-time | 5 ± 2 |
| min |
Curing | 65 ± 5 | 30 ± 5 | min |
Thermal properties of cured compound
Property | Condition | Value | Unit |
Coefficient of thermal expansion, Beck Test M 56 | -20°C to + 90°C | 200·10-6 | K-1 |
Thermal conductivity, DIN 52616 | 23°C | 0,18 ± 0,02 | W/mK |
