Flowable silicone offers thermal cycling and shock resistance

Master Bond MasterSil 323 is a two component, addition cured system for bonding, sealing and potting applications. This product has a convenient to use 1:1 mix ratio, and can be packaged in double barrel cartridges for dispensing from a gun applicator.

It can be applied in thin and thick sections. This silicone has excellent flexibility, with an elongation of 150-250% at room temperature, a Shore A hardness of 35-45 and a low tensile modulus of 100-175 psi at 75°F for stress relief. It is capable of withstanding rigorous thermal cycling and shock without cracking or exerting stress on components. Additionally, MasterSil 323 has a low dielectric constant of 2.8 at 75°F, 1 MHz.

“MasterSil 323 is a specialty compound which not only offers strain relief upon cure, but also provides decent bond strength to a variety of substrates, especially considering that it is a silicone,” says senior product engineer Rohit Ramnath. “The lap shear strength for an aluminium-to-aluminium bond joint is around 200-250 psi at 75°F. Moreover, MasterSil 323 is optically clear in thinner sections and has a refractive index of 1.44 at 589 nm. It has a wide service temperature range of -65°F to 400°F.”

The optimal cure schedule for MasterSil 323 is overnight at room temperature followed by 2-4 hours at 135-165°F. The material will fully cure without exposure to air or humidity. The working life of a mixed 100 gram batch is approximately 2-3 hours. It also has extremely low shrinkage upon curing.

MasterSil 323 is available for use in half pint, pint, quart, gallon kit containers, 30 cc syringe kits, and 50 cc double barrel cartridges for gun dispensers. Shelf life in original, unopened containers at 75°F is 6 months.