UDC SIL 635MT encapsulating resin is a high strength, room-temperature curing silicone elastomer supplied as a two-component pourable system. The cured clear-to-translucent product represents a three to four fold increase in tear strength over other available pourable silicone elastomers. UDC SIL 635MT also has good dielectric properties and can operate at a wide temperature range, i.e., -85 to 482° F (-65 to 250° C) with no post-cure. Other features include:
o No shrinkage when cured at room temperature
o Unlimited thick section cure
o Resistant to depolymerization upon confined heating
o Self-extinguishing
o No exothermic heat
o Heat accelerated cure
o Physical and electrical stability
o High elongation
o Firmness and flexibility
TYPICAL PROPERTIES*
As Supplied:
Color, Curing Agent....................................Clear
Elastomer Base............................................Bright to grayish pink
Viscosity
Base, Poise.................................................1100
with 7 parts per 100 of curing agent,
0 hours, poises..............................................550
2 hours, poises.............................................1000
Pot life, with 7 pph curing agent
added, hours.................................................>2
Physical – as cured 1 hr. at 150°C (302°F)
Tear Strength, die B ppi..................................90
Elongation, die C, percent.............................420
Tensile Strength, die C psi............................ 700
Durometer hardness, Shore A, points............. 32
Specific Gravity at 77°F (25°C)................... 1.12
Nonvolatile Content, percent........................ >98
Water vapor permeability g24 hr sq
meter mm Hg/cm thickness...........................0.00108
Electrical – as cured 1 hr. at 150°C (302°F)
Dielectric Strength, volt/mil..............................575
Volume Resistivity, ohm-cm............................2 x 1015
Dielectric Constant
100 Hz.............................................................3.01
100 KHz. ........................................................3.00
Dissipation Factor,
100 Hz............................................................0.0009
100 KHz.........................................................0.001
Surface Resistivity............................................7 x 1016
APPLICATION SUGGESTIONS
Compatibility: UDC SIL635MT encapsulating resin will cure when in contact with most materials found in electronic equipment. Exceptions that have been noted are butyl and chlorinated rubbers, some RTV silicone rubbers and residual amine catalysts from resin systems such as epoxies. Substrates that inhibit the proper curing of UDC SIL635MT can be made compatible by washing with solvent or by heating. No corrosion has been observed on any common metals, including copper, when using UDC SIL635MT.
Curing: After mixing, UDC SIL635MT encapsulating resin will remain workable for a minimum of two hours. Room temperature cure is achieved in about 24 hours. UDC SIL635MT is adaptable to elevated temperature cure. It may be fully cured with any of the following schedules:
4 hours at 65 oC (150°F)
1 hour at 100 oC (212°F)
15 minutes at 150 oC (302°F)
Adhesion and Release: UDC SIL635MT encapsulating resin releases well for smooth, unprimed surfaces other than glass. A release agent may be used to insure trouble-free release. A 2% to 5% solution of a non-bleach-containing household detergent such as Ivory liquid is useful.
|
