Are chemical compounds with a backbone of alternating silicon (Si) and oxygen (O) atoms, each silicon atom bearing one or several organic groups, as be seen in the image 1, are very flexible due to large bond angles and bond lengths compared to those found in more basic polymers. Siloxanes are building blocks for silicone products or make part of other products, such as cosmetics or paint.
Image 1: Representation of the chemical structure of Silicones
¿What Makes Silicone Rubber Versatile?
Polymers are widely used in industry and in our daily life because of their diverse functionality:
- Light weight
- Low cost
- Excellent chemical stability.
However, on some applications such as heat exchangers and electronic packaging, the low thermal conductivity of polymers is one of the major technological barriers.
Long-term, reliable protection of sensitive electronic components is essential to many electronic applications today. Increasingly small systems and rising circuit densities have resulted in hotter operating temperatures, and driven demand for high-performance solutions for heat dissipation.
Silicones come in a variety of forms:
Oils and gums that can be formulated in fluids (emulsions, resins, greases, compounds) or elastomers. Thanks to its versatility, silicones are used in a wide range of applications. Typically, silicones are presents in every technologic device for protecting micro-electronics with potting and encapsulation, as well as in every car in the world for sealing and bonding functionalities.
Silicones have amazing array of properties, as it can be observed in the list below:
- Thermal stability (from -80°C to 250°C), ensuring proper viscosity in a wide temperature range
- Resistance to natural ageing (oxidation, UV)
- Low hardness
- Low modulus for compensation of stress in high temperature or cycling conditions.
- High fire resistance capabilities,
- Low surface energy
- Good wetting on many substrates
- Hydrophobia (beading effect) to ensure waterproofing
- Easy re-workability or strong adhesion depending on requirements
- Extremely low inner stress on potted components, preventing delamination from the housing substrate
Finally, in list below, it can be observed the performance characteristics silicone versus others resins
Table 1: Properties of different types of resins