1. A mechanical assembly, comprising at least one mechanical structure, which comprises:
two bodies having different coefficients of thermal expansion;
at least one coefficient of thermal expansion adapting means that interconnects the two said bodies via two interconnecting interfaces, which are flat and parallel to each other; the coefficient of thermal expansion adapting means has coefficient of thermal expansion gradually varied in the direction perpendicular to the said interconnecting interfaces; at each interconnecting interface, the coefficient of thermal expansion directional components of the coefficient of thermal expansion adapting means match the coefficient of thermal expansion directional components of the adjacent body in all directions parallel to the interconnecting interfaces.
2. A mechanical assembly of claim 1 wherein the coefficient of thermal expansion adapting means is bonded to at least one said body at the interconnecting interface.
3. A mechanical assembly of claim 1 wherein the coefficient of thermal expansion adapting means is non-isotropic, having different values of coefficient of thermal expansion directional components.
4. A mechanical assembly of claim 3 wherein the coefficient of thermal expansion adapting means has near zero value of coefficient of thermal expansion directional component in the direction perpendicular to the said interconnecting interfaces.
5. A mechanical assembly of claim 1 wherein the coefficient of thermal expansion adapting means is made of composite material.
6. A mechanical assembly of claim 5 wherein the coefficient of thermal expansion adapting means material is made by pressing and sintering processes of solid powders.
7. A mechanical assembly of claim 5 wherein the coefficient of thermal expansion adapting means material is made by the sol-gel process.
8. A mechanical assembly of claim 1 wherein the coefficient of thermal expansion adapting means comprises multiple layers with uniform thickness, having different coefficients of thermal expansion, and are bonded together along the bonding interfaces parallel to the interconnecting interfaces in a specific order to form a composite body having coefficient of thermal expansion gradually varied in only one direction, which is perpendicular to the said bonding interfaces.
9. A mechanical assembly of claim 8 wherein the material of said multiple layers is made by pressing and sintering processes of solid powders.
10. A mechanical assembly of claim 8 wherein the material of said multiple layers is made by the sol-gel process.
11. A solid body comprising two flat outer surfaces, parallel to each other; the said body is made of material having coefficient of thermal expansion gradually varied in the direction perpendicular to the said two flat outer surfaces.
12. A solid body of claim 11 wherein the said body is made of non-isotropic material having different values of coefficient of thermal expansion directional components.
13. A solid body of claim 12 wherein the said body is made of material having near zero value of coefficient of thermal expansion directional component in the direction perpendicular to the said two flat outer surfaces.
14. A solid body of claim 11 wherein the said body is made of composite material.
15. A solid body of claim 11 wherein the said body comprises multiple layers with uniform thickness, having different coefficients of thermal expansion, and are bonded together along the bonding interfaces parallel to the said two flat outer surfaces in a specific order to form a composite body having coefficient of thermal expansion gradually varied in only one direction, which is perpendicular to the said bonding interfaces.
16. A solid body of claim 15 wherein the material of said multiple layers is fabricated by pressing and sintering processes of solid powders.
17. A solid body of claim 16 wherein the said multiple layers are bonded by pressing the layers and sintering them together.
18. A solid body of claim 15 wherein the material of said multiple layers is fabricated by the sol-gel process.
19. A solid body of claim 18 wherein the said multiple layers are bonded by the sol-gel process.
20. A solid body of claim 15 wherein multiple layers are fabricated and bonded together by sputtering process; the first layer material is sputtered onto a flat surface mold, and each subsequent layer material is sputtered directly on top of the previously sputtered adjacent layer in a specific order.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A semiconductor package comprising a semiconductor chip, leads for conveying electrical signals, and bonding wires for electrically connecting said chip and said leads, at least portions of said chip, said bonding wires and said leads being covered and protected with an electrically insulating fluorochemical material, wherein
said fluorochemical material is a cured product of a curable composition comprising
(A) 100 parts by weight of a chain-like polyfluorodialkenyl compound having alkenyl groups at both ends of its molecular chain and comprising a backbone represented by the formula:
(B) an effective amount of an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms in a molecule, and
(C) a catalytic amount of a platinum group metal catalyst.
2. The semiconductor package of claim 1, wherein said fluorochemical material has a relative permittivity of up to 2.5 in a frequency range of at least 1 MHz.
3. The semiconductor package of claim 1, wherein said curable composition further comprises (D) 40 to 160 parts by weight of a chain-like polyfluoromonoalkenyl compound having an alkenyl group at one end of its molecular chain and comprising a backbone represented by the formula:
4. The semiconductor package of claim 1, wherein said curable composition further comprises (E) 0.1 to 3.0 parts by weight of an organosilicon compound having at least one of trialkoxysilyl and epoxy groups in a molecule.
5. The semiconductor package of claim 1, wherein component (A) is a branched chain-like polyfluorodialkenyl compound having the general formula (1):
CH2\u2550CH\u2014(X)a\u2014Rf1\u2014(X\u2032)a\u2014CH\u2550CH2\u2003\u2003(1)
wherein X is a divalent group selected from among \u2014CH2\u2014, \u2014CH2O\u2014, \u2014CH2OCH2\u2014 and \u2014Y\u2014NR1\u2014CO\u2014, wherein Y is \u2014CH2\u2014 or a divalent group of the formula:
and R1 is hydrogen or a substituted or unsubstituted monovalent hydrocarbon group,
X\u2032 is a divalent group selected from among \u2014CH2\u2014, \u2014OCH2\u2014, \u2014CH2OCH2\u2014 and \u2014CO\u2014NR1\u2014Y\u2032\u2014, wherein Y\u2032 is \u2014CH2\u2014 or a divalent group of the formula:
and R1 is as defined above,
\u201ca\u201d is independently 0 or 1,
Rf1 is a divalent group of the general formula (i):
\u2014CtF2t\u2014OCF2CF(CF3)p\u2014OCF2(CF2)rCF2O\u2014CF(CF3)CF2Oq\u2014CtF2t\u2014\u2003\u2003(i)
wherein p and q each are an integer of at least 1, the sum of p and q is 2 to 200 on average, r is an integer of 0 to 6, and t is 2 or 3,
or the general formula (ii):
\u2014CtF2t\u2014OCF(CF3)CF2u\u2014(OCF2)v\u2014OCtF2t\u2014\u2003\u2003(ii)
wherein u is an integer of 1 to 200, v is an integer of 1 to 50, and t is as defined above.
6. The semiconductor package of claim 3, wherein component (D) is a branched chain-like polyfluoromonoalkenyl compound having the general formula (2):
Rf2\u2014(X\u2032)a\u2014CH\u2550CH2\u2003\u2003(2)
wherein X\u2032 and \u201ca\u201d are as defined in claim 5, Rf2 is a group of the general formula (iii):
F\u2014CF(CF3)CF2Ow\u2014CtF2t\u2014\u2003\u2003(iii)
wherein w is an integer of at least 1 and t is as defined above.