Bluesil™ ESA 7242 is a two-component heat curing liquid silicone elastomer that cross-links by a polyaddition reaction. This product is well suited for applications that require a heat curable silicone elastomer for potting of electronics. These products cure without regard to the thickness of the material, and cure rate is controlled by the temperature of cure. For many applications the use of a primer may be required if adhesion is necessary.
Mix Parts A and B separately before blending together. Some filler separation with a small amount of liquid at the top of the container is normal. Once the Parts A and B have been mixed individually in their original containers, both parts ban be mixed together at a 1:1 mix ratio by weight or volume and then the blend can be poured into place over desired electronic assembly.
Bubbles may gather in the material during the mixing and pouring processes. If this is not desired, then the material must be deaired. Deairing can be accomplished by placing the mixed product and part in a vacuum chamber and reducing the pressure over the material until the bubbles rise and break.
Alternatively, another method to add silicone to a desired container without capturing bubbles is to use an automated dispensing machine with a vacuum deairing feature. The Parts A and B will be deaired in individual containers under vacuum and then pumped and mixed through a static mixing head to provide air free mixed product prior to cure.
Cure can be accomplished simply by leaving the product for 24 hours at room temperature (or longer if desired). However, the recommended method for cure is via a heat cure. This can be accomplished via a 90 minute cure at +100°C, 20 minute cure at +120°C, or a 5 minute cure at +150°C. Contact Bluestar Silicones if alternative or more defined temperature cure times are needed. Note: Make sure to account for a lag in the time it takes for parts to heat up. A large heavy part may take longer to cure than is indicated here.