US 2008/0185601 A1 · Process and Silicone Encapsulant Composition for Molding Small Shapes

Abstract

A process includes the steps of: 1) heating a mold at a temperature ranging from 100° C. to 200° C.; 2) feeding a silicone encapsulant composition including a mold release agent, where the composition has a viscosity ranging from 100 cps to 3,000 cps at operating temperatures of the process, to an assembly for preventing the silicone encapsulant composition from flowing backward out of the assembly; 3) injecting the silicone encapsulant composition from the assembly into a mold having a horizontal orientation and having a mold cavity through a gate, where the mold cavity has a top and a bottom, a vent is located at the top of the mold cavity, the vent comprises a channel 0.1 mm to 1 mm wide by 0.0001 mm to 0.001 mm deep, the gate is located at the bottom of the mold cavity, and injecting is performed at a pressure ranging from 1,000 psi to 10,000 psi for up to 5 seconds; 4) holding the silicone encapsulant composition at 1,000 psi to 10,000 psi for an amount of time sufficient to prevent the silicone encapsulant composition from flowing out of the mold cavity; 5) curing the product of step 4). Lenses for LED packages may be prepared by the process.

Claims14

Dependent claims

A process comprising:

1) heating a mold having a mold cavity at a temperature ranging from 100° C. to 200° C.;
2) feeding a quantity of a silicone composition including a mold release agent, where the composition has a viscosity ranging from 50 cps to 3,000 cps at operating temperatures of the process, to an assembly for preventing the silicone encapsulant composition from flowing backward out of the assembly;
3) injecting the silicone composition from the assembly into the mold cavity through a gate, where
the mold cavity has a top and a bottom,
a vent is located at the top of the mold cavity,
the vent comprises a channel 0.1 mm to 1 mm wide by 0.0001 mm to 0.001 mm deep,
the gate is located at the bottom of the mold cavity, and
injecting is performed at a pressure ranging from 1,000 psi to 10,000 psi for up to 5 seconds;
4) holding the silicone composition at 1,000 psi to 10,000 psi for an amount of time sufficient to prevent the silicone composition from flowing out of the mold cavity;
5) curing the product of step 4).

7 more elements

A composition comprising:

(A) 100 parts of an organopolysiloxane resin represented by average compositional formula
R1aR2bSiO(4-a-b)/2 (1)
where each R1 is independently an alkenyl group having 2 to 10 carbon atoms, each R2 is independently a substituted or unsubstituted monovalent hydrocarbon group other than R1, with the proviso that at least 50 mole % of R2 comprise phenyl groups, subscript “a” has a value ranging from 0.09 to 0.16, and subscript “b” has a value ranging from 1.00 to 1.20;
with the provisos that (i) the organopolysiloxane resin comprises alkenyl groups and phenyl groups and (ii) the organopolysiloxane resin has a weight-average molecular weight equal to or exceeding 3000 with polystyrene as reference and determined by gel chromatography;
(B) 10 to 50 parts by weight of an organooligosiloxane represented by average compositional formula
R3cR4dSiO(4-c-d)/2 (2)
where each R3 is independently an alkenyl group having 2 to 10 carbon atoms, each R4 is independently a substituted or unsubstituted monovalent or non-substituted monovalent hydrocarbon group other than R3, with the proviso that at least 10 mole % of R4 comprise phenyl groups;
subscript “c” has a value ranging from 0.60 to 0.80, and subscript “d” has a value ranging from 1.50 to 2.10;
with the proviso that the organooligosiloxane comprises alkenyl groups and phenyl groups;
(C) 20 to 100 parts by weight of an organohydrogenoligosiloxane or organohydrogenpolysiloxane represented by average compositional formula
HeR5fSiO(4-e-f)/2 (3)
where each R5 is independently a substituted or unsubstituted monovalent or non-substituted monovalent hydrocarbon group other than alkenyl groups, with the proviso that at least 20 mole % of R5 comprise phenyl groups;
subscript “e” has a value ranging from 0.35 to 0.65, and subscript “f” has a value ranging from 0.90 to 1.70;
(D) a catalytic quantity of an addition-reaction catalyst;
and
(E) 0.2% to 2% parts by weight of a mold release agent;
where
the composition is curable to form an article having a hardness of 60 to 100 at 25° C. and 40 to 100 at 150° C. as measured by ASTM D2240-86.

15 more elements

Dependencies are inferred from the claim text.

Process and Silicone Encapsulant Composition for Molding Small Shapes

Life of this patent

Process and Silicone Encapsulant Composition for Molding Small Shapes

Life of this patent

Abstract

Claims14