SEMICOSIL® 924

Because of the thixotropic behavior, SEMICOSIL® 924 is specially recommended for local encapsulation of delicate electronic components, e.g. bonded chips on hybrid components which are exposed to extreme external influences.

Processing

Surface preparation

All surfaces must be clean and free of contaminants that will inhibit the cure of SEMICOSIL® 924. Examples of inhibiting contaminants are sulfur containing materials, plasticizers, urethanes, amine containing materials and organometallic compounds – especially organotin compounds. If a substrate’s ability to inhibit cure is unknown, a small scale test should be run to determine compatibility.

Dispensing

Because of the thixotropy (shear thinning effect) SEMICOSIL 924 can be dispensed easily with all dispensing equipments. To eliminate any air introduced during dispensing or trapped under components or devices a vacuum encapsulation is recommended.

Curing

• SEMICOSIL® 924 works best when cured at 100 °C or more depending on the size and heat sink properties of the components. The reactivity can be adjusted within wide limits by adding Catalyst EP or Inhibitor PT 88 to suit the processing requirements of the particular application.
• Catalyst EP increases the reactivity, i. e., pot life and curing time are reduced. Inhibitor PT 88 is a pot life extender and prolongs pot life and curing time.

• One-part, ready-to-use
• Thixotropic flow
• Forms a soft gel on vulcanization
• Low content of volatiles
• Low content of uncured polymer
• Low ion content
• Almost constant properties between –50 °C and +180 °C

Cured properties are cured for 30 min at 150 °C in a circulating air oven.