Silicone gels are typically composed of a very lightly cross-linked silicone elastomer whose polymer network has been swollen with silicone fluids or, less commonly, nonsilicone fluids, such as mineral oil. It’s important to note that these gels do not contain any silica or other types of fillers. Typically, silicone gel comes in a two-part fluid system and undergoes a curing process through a platinum-catalyzed addition reaction.
The Properties of Silicone Gel
Silicone gels are a type of two-component material that utilizes addition (platinum) cure chemistry. Most silicone gels are designed with a one-to-one mix ratio system. They can be cured at room temperature or subjected to heat for faster processing. Dispensing can be done either automatically or by hand. Specialty gels can also be formulated to cure solely with the application of heat, allowing for an extended pot life.
Silicone gels find extensive use in various electronic applications where a soft and highly flexible encapsulation or potting material is required. These gels serve to safeguard delicate components and assemblies from vibration, thermal and mechanical shocks, as well as protect against moisture corrosion and other harsh environmental factors.
Many silicone gels have an optically clear appearance, but they can be tinted for visual identification if needed. Alternatively, fillers can be added to produce tougher, more rigid gels when optical clarity is not a requirement.
Silicone gels are available in a range of hardnesses, penetrations, and viscosities. Gels with low viscosity can easily flow around intricate components, while thixo-gels can be used in situations where non-slumping or sagging properties are necessary. Silicone gels typically offer a priceless, “pressure sensitive” type bond to most substrates. However, chemical adhesion can be achieved by using a primer.
Here are some notable properties of silicone gels:
- Wide operating temperature range: -55ºC to 200ºC
- Excellent electrical properties
- Flame retardant, with UL listed grades available
- Range of refractive indices
- UV resistant catalysts that prevent yellowing
- Low modulus materials that minimize strain caused by thermal expansion
- Good resistance to chemicals, water, and humidity
- Repairable and self-healing grades
- Adhesion to many substrates, including glass, aluminum, and copper
Silicone Gel Applications
Silicone gels find applications in various industries such as electronics, aerospace, automotive, solar/energy, and healthcare.
Electronics: Electronic protection, Optical bonding, Gap pads, Gap fillers. These gels are supple yet durable, offering a protective shield against moisture and environmental pollutants. They alleviate the mechanical and thermal strains commonly experienced by high-voltage devices. Moreover, their properties such as adhesion, modulus, temperature range, and conductivity can all be tailored to suit your specific application.
Aerospace: Silicone gel finds application in the aerospace industry with the following benefits:
- Moisture protection: Silicone gel provides effective protection against moisture, safeguarding sensitive aerospace components.
- Excellent shock and vibration resistance: The gel exhibits high resilience, effectively absorbing and dampening shock and vibration in aerospace applications.
- Adhesion through room temperature and heat curing: Silicone gel offers reliable adhesion properties, capable of bonding components through both room temperature and heat curing methods.
- Low-temperature capabilities: Certain silicone gel products are designed to withstand extremely low temperatures, offering reliable performance even in environments as cold as -110°C.
Health Care: Silicone gels find application in the production of cushioned external prosthetics, whereas sticky gels can serve as an adhesive for these prosthetics. Due to their softness and ability to maintain their shape once cured, silicone gels offer a comfortable padding solution for hospital beds, wheelchair pillows, and the cushioning of shoe soles. In addition, Silicone Gel is also used in scar treatment, in making ointments for skin diseases.
And A1 Silicones is a global distributor of advanced silicones. For more information, contact A1 Silicone.