Conducive, silicone-based compositions with improved initial adhesion reduced microvoiding

A curable conductive composition comprising:

• (a) a reactive polyorganosiloxane component;
• (b) a silicone resin formed as a hydrolysis and condensation product of at least one silane within the formula R1mR2pSi(X)4-(m+p), wherein R1 and R2 may be the same or different and may be selected from the group consisting of monovalent ethylenically unsaturated radicals, C1-12 alkoxy, C6-12 aryloxy, (meth) acrylate, hydrogen, C1-12 alkyl, C6-12 aryl, C7-18 arylalkyl, and C7-18 alkylaryl, X is a hydrolyzable functionality, m is an integer from 1 to 3, and m+p is an integer from 1 to 3 provided at least one of R1 and R2 is a member selected from the group consisting of monovalent ethylenically unsaturated radicals, C1-12 alkoxy, C6-12 aryloxy, (meth)acrylate hydrogen;
• and
• (c) a conductive filler component, wherein the composition demonstrates an improved initial adhesion to a substrate with which it is to be used of at least about 7%;
• and wherein at least one of the polyorganosiloxane component and the silicone resin component is moisture curable.

A process for preparing a conductive composition, said process comprising the steps of:

• (a) providing a curable conductive composition comprising:
• (i) a reactive polyorganosiloxane component;
• (ii) a silicone resin formed as a hydrolysis and condensation product of at least one silane within the formula R1mR2pSi(X)4-(m+p), wherein R1 and R2 may be the same or different and may be selected from the group consisting of monovalent ethylenically unsaturated radicals, C1-12 alkoxy, C6-12 aryloxy, (meth)acrylate, hydrogen, C1-12 alkyl, C6-12 aryl, C7-18 arylalkyl, and C7-18 alkylaryl, X is a hydrolyzable functionality, m is an integer from 1 to 3, and m+p is an integer from 1 to 3 provided at least one of R1 and R2 is a member selected from the group consisting of monovalent ethylenically unsaturated radicals, C1-12 alkoxy, C6-12 aryloxy, (meth)acrylate hydrogen;
• and
• (iii) a conductive filler component, wherein the composition demonstrates an improved initial adhesion to a substrate with which it is to be used of at least about 7%, and
• b) shearingly dispersing the components thereof by application of shear mixing forces to form a substantially homogeneous composition in which the conductive filler is densely packed in the composition.

A process for using a conductive composition to bond a pair of substrates, said process comprising the steps of:

• (a) dispensing a curable conductive composition comprising:
• (i) a reactive polyorganosiloxane component;
• (ii) a silicone resin formed as a hydrolysis and condensation product of at least one silane within the formula R1m R2pSi(X)4-(m+p), wherein R1 and P2 may be the same or different and may be selected from the group consisting of monovalent ethylenically unsaturated radicals, C1-12 alkoxy, C6-12 aryloxy, (meth)acrylate, hydrogen, C1-12 alkyl, C6-12 aryl, C7-18 arylalkyl, and C7-18 alkylaryl, X is a hydrolyzable functionality, m is an integer from 1 to 3, and m+p is an integer from 1 to 3 provided at least one of R1 and R2 is a member selected from the group consisting of monovalent ethylenically unsaturated radicals C1-12 alkoxy, C6-12 aryloxy, (meth)acrylate hydrogen;
• and
• (iii) a conductive filler component, wherein the conductive filler component comprise:
• a) a first conductive filler and
• b) a second conductive filler wherein the first conductive filler is relatively harder than the second conductive filler using a Mohs hardness test, wherein the composition is subjected to shear mixing forces which shearingly disperse the first and second conductive fillers throughout the composition so as to provide a volume fraction of conductive filler throughout the resinous material in the range of about 30 to about 65% by volume of the composition and wherein the composition demonstrates an improved initial adhesion to a substrate with which it is to be used of at least about 7% onto a surface of at least one of the substrates;
• (b) joining the other substrate therewith;
• and
• (c) exposing the joined substrates to conditions favorable to cure the conductive composition.