Silicones having improved chemical resistance and curable silicone compositions having improved migration resistance

1. A method comprising:

(1) applying a composition over an electronic circuit board, and

(2) curing the composition to produce a sealed circuit board;

where the composition is prepared by mixing components comprising:

(I) a polyorganosiloxane having an average of at least two unsaturated organic groups per molecule,

with the proviso that component (I) is free of fluorine atoms;

optionally (II) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule,

with the proviso that component (II) is free of fluorine atoms;

(III) a hydrosilylation catalyst;

(IV) a fluoroorganosilicone,

with the provisos that

(1) component (IV) has at least one functional group reactive with component (I), component (II), or both,

(2) when component (II) is not present, then component (IV) has an average of at least two silicon-bonded hydrogen atoms per molecule, and

(3) component (IV) is added to the composition in an amount sufficient to provide chemical resistance to a cured product of the composition; and

(V) an adhesion promoter comprising a reaction product of a hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane or an unsaturated alkoxysilane, or a physical blend of a hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane or an unsaturated alkoxysilane,

with the proviso that component (IV) and component (V) are added to the composition in amounts sufficient to provide resistance to Bleed to the composition.

2. The method of claim 1 , where the substrate comprises an epoxy, a polycarbonate, a poly(butylene terephthalate) resin, a polyamide resin, a blend of polyamide resin with syndiotactic polystyrene, an acrylonitrile-butadiene- styrene, a styrene-modified poly(phenylene oxide), a poly(phenylene sulfide), a vinyl ester, a polyphthalamide, a polyimide, silicon, aluminum, a stainless steel alloy, titanium, copper, nickel, silver, gold, or combinations thereof.

3. The method of claim 1 , where component (V) comprises an alkoxysilane of the formula R 28 μ Si(OR 29 ) (4-μ) , where

μ is 1, 2, or 3,

each R 28 is independently a monovalent organic group, with the proviso that at least one R 28 is an unsaturated organic group or an epoxy-functional group, and

each R 29 is independently an unsubstituted, saturated hydrocarbon group of at least 1 carbon atom.

4. A method comprising:

(1) applying a composition on an electronic substrate,

(2) attaching a semiconductor die to the composition,

(3) curing the composition to produce a bonded composite,

optionally (4) repeating steps (1) to (3) to attach one or more additional semiconductor dice to the semiconductor die,

optionally (5) wire bonding the semiconductor die or semiconductor dice,

optionally (6) cleaning,

optionally (7) overmolding the semiconductor die or semiconductor dice with a molding compound, and

optionally (8) attaching solder balls to form a finished package;

where the composition is prepared by mixing components comprising:

(I) a polyorganosiloxane having an average of at least two unsaturated organic groups per molecule,

with the proviso that component (I) is free of fluorine atoms;

optionally (II) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule,

with the proviso that component (II) is free of fluorine atoms;

(Ill) a hydrosilylation catalyst;

(IV) a fluoroorganosilicone,

with the provisos that

(1) component (IV) has at least one functional group reactive with component (I), component (II), or both,

(2) when component (II) is not present, then component (IV) has an average of at least two silicon-bonded hydrogen atoms per molecule, and

(3) component (IV) is added to the composition in an amount sufficient to provide chemical resistance to a cured product of the composition; and

(V) an adhesion promoter compriding a reaction product of a hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane or an unsaturated alkoxysilane, or a physical blend of hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane or an unsaturated alkoxysilane,

with the proviso that component (IV) and component (V) are added to the composition in amounts sufficient to provide resistance to Bleed to the composition.

5. The method of claim 4 , where the substrate comprises an epoxy, a polycarbonate, a poly(butylene terephthalate) resin, a polyamide resin, a blend of polyamide resin with syndiotactic polystyrene, an acrylonitrile-butadiene- styrene, a styrene-modified poly(phenylene oxide), a poly(phenylene sulfide), a vinyl ester, a polyphthalamide, a polyimide, silicon, aluminum, a stainless steel alloy, titanium, copper, nickel, silver, gold, or combinations thereof.

6. The method of claim 4 , where component (I) comprises a polyorganosiloxane of the formula:

(a) R 1 3 SiO(R 1 2 SiO) α (R 1 R 2 SiO) β SiR 1 3 ,

(b) R 3 2 R 4 SiO(R 3 2 SiO) χ (R 3 R 4 SiO) δ SiR 3 2 R 4 , or

(c) a combination thereof, where

α has an average value of 0 to 2000,

β has an average value of 2 to 2000,

each R 1 is independently a monovalent organic group,

each R 2 is independently an unsaturated monovalent organic group,

χ has an average value of 0 to 2000,

δ has an average value of 0 to 2000,

each R 3 is independently a monovalent organic group, and

each R 4 is independently an unsaturated monovalent organic group.

7. The method of claim 4 , where component (I) comprises an MQ resin consisting essentially of R 5 3 SiO 1/2 units and SiO 4/2 units, a TD resin consisting essentially of R 5 SiO 3/2 units and R 5 2 SiO 2/2 units, an MT resin consisting essentially of R 5 3 SiO 1/2 units and R 5 SiO 3/2 units, an MTD resin consisting essentially of R 5 3 SiO 1/2 units, R 5 SiO 3/2 units, and R 5 2 SiO 2/2 units, or a combination thereof, where

each R 5 is a monovalent organic group of 1 to 20 carbon atoms, and

the resin contains an average of 3 to 30 mole percent of unsaturated organic groups.

8. The method of claim 4 , where component (II) is present and component (II) comprises siloxane units selected from HR 6 2 SiO 1/2 , R 6 3 SiO 1/2 , HR 6 SiO 2/2 , R 6 2 SiO 2/2 , R 6 SiO 3/2 , SiO 4/2 , or combinations thereof; where each R 6 is independently selected from monovalent organic groups free of aliphatic unsaturation.

9. The method of claim 4 , where component (II) is present and component (II) comprises a compound of the formula:

(a) R 7 3 SiO(R 7 2 SiO) ε (R 7 HSiO) ø SiR 7 3 , or

(b) R 8 2 HSiO(R 8 2 SiO) γ (R 8 HSiO) η SiR 8 2 H,

(c) a combination thereof, where

ε has an average value of 0 to 2000,

ø has an average value of 2 to 2000,

each R 7 is independently a monovalent organic group free of aliphatic unsaturation,

γ has an average value of 0 to 2000,

η has an average value of 0 to 2000, and

each R 8 is independently a monovalent organic group free of aliphatic unsaturation.

10. The method of claim 4 , where component (Ill) comprises a platinum metal, a rhodium metal, or an organometallic compound.

11. The method of claim 4 , where component (Ill) comprises a microencapsulated hydrosilylation catalyst.

12. The method of claim 4 , where component (IV) comprises a compound of the formula:

(a) R 9 3 SiO(R 9 2 SiO) ι (R 9 R 10 SiO) φ SiR 9 3 ,

(b) R 11 2 R 12 SiO(R 11 2 SiO) κ (R 11 R 12 SiO) λ SiR 11 2 R 12 ,

(c) F 3 C(CF 2 ) ν R 13 —Si—[O—Si(R 14 ) 2 (R 15 )] 3 ,

(d) a resinous or branched structure consisting essentially of R 15 R 14 2 SiO 1/2 units, CF 3 (CF 2 )νR 13 SiO 3/2 units, and optionally SiO 4/2 units, or

(e) a combination thereof; where

ι has an average value of 0 to 2000,

φ has an average value of 1 to 500,

each R 9 is independently a hydrogen atom or a monovalent organic group, with the proviso that at least one R 9 is a hydrogen atom or an unsaturated monovalent organic group;

each R 10 is independently a fluoro-functional organic group;

κ has an average value of 0 to 2000;

λ has an average value of 0 to 500;

each R 11 is independently a hydrogen atom or a monovalent organic group, with the proviso that at least one R 11 is a hydrogen atom or an unsaturated monovalent organic group;

each R 12 is independently a fluoro-functional organic group;

each R 13 is independently a divalent organic group;

each R 14 is independently a monovalent hydrocarbon group free of aliphatic unsaturation;

ν is 0 to 10; and

each R 15 is independently a hydrogen atom or an unsaturated monovalent organic group.

13. The method of claim 4 , where component (V) comprises an alkoxysilane of the formula R 28 μ Si(OR 29 ) (4-μ) , where

μ is 1, 2, or3,

each R 28 is independently a monovalent organic group, with the proviso that at least one R 28 is an unsaturated organic group or an epoxy-functional group, and

each R 29 is independently an unsubstituted, saturated hydrocarbon group of at least 1 carbon atom.

14. The method of claim 4 , where the composition further comprises an acid acceptor, an anti-oxidant, a stabilizer, a flame retardant, a flow control additive, a reactive diluent, an anti-settling agent, a silylating agent, a desiccant, a blowing agent, or combinations thereof.