Abradable silicone elastomer compound and use thereof
Addition curing silicone elastomers of high Shore D hardness are grindable and polishable, and are particularly useful as temporary adhesives in the processing of semiconductor wafers.
1. An addition-crosslinkable silicone elastomer composition comprising:
(A1) 1-10% by weight of at least one linear organopolysiloxane containing at least 2 SiC-bonded radicals having aliphatic carbon-carbon multiple bonds, wherein the mean molar mass of (A1) is not more than 15,000 g/mol,
(A2) 1-20% by weight of at least one linear organopolysiloxane containing at least 2 SiC-bonded radicals having aliphatic carbon-carbon multiple bonds, wherein the mean molar mass of (A2) is at least 40,000 g/mol,
(B) 1-40% by weight of at least one organopolysiloxane containing at least three Si-bonded hydrogen atoms per molecule, having a content of Si-bonded hydrogen of from 0.04 to 1.7% by weight and a mean molar mass of not more than 20,000 g/mol,
(D) 1-100 ppm (based on the metal) of a hydrosilylation catalyst,
(E) 50-99% by weight of at least one branched silicone resin of the general empirical formula (I)
(R 3 3 SiO 1/2 ) l (R 4 R 3 2 SiO 1/2 ) t (R 4 R 3 SiO) u (R 3 2 SiO) p (R 4 SiO 3/2 ) q (R 3 SiO 3/2 ) r (SiO 4/2 ) s (I),
wherein
R 3 denotes a linear aliphatic radical,
R 4 denotes an aliphatically unsaturated radical having a terminal C═C double bond,
l, t, u, p, q, r and s denote integers,
wherein the following apply:
l≧0, t≧0, u≧0, p≧0, q≧0, r≧0 and s≧0; and
the content of aliphatically unsaturated groups in (E) is between 0.2 and 10 mmol/g; and
(E) has a mean molar mass of not more than 10 5 g/mol,
with the proviso that the ratio of the Si—H groups provided by component (B) to the aliphatically unsaturated groups provided by components (A1), (A2) and (E) is between 0.5 and 5 and the ratio of the dynamic viscosity of the silicone elastomer composition at shear rates of 1 s −1 and 100 s −1 and a temperature of 20° C. is not more than 1.2 and after crosslinking exhibits a Shore D hardness of at least 25.
2. A process for the preparation of a silicone elastomer compositions of claim 1 , wherein all the components are mixed together.
3. A molding, adhesive bond or optical component, comprising a cured silicone elastomer of claim 1 .
4. The adhesive bond of claim 3 , which is a temporary adhesive bond.
5. In the processing of a semiconductor wafer wherein an adhesive is used to bond the wafer to a substrate in temporary fashion, the improvement comprising employing an adhesive which is a curable silicone elastomer composition of claim 1 .