Polymer-ceramic composite plies

Claim 2

A composite ply comprised of a planarly oriented plurality of high thermal conductivity, low thermal expansion coefficient, moderately low dielectric constant crystalline ceramic fibers embedded in a low dielectric constant resin matrix, the composite having an out-of-plane dielectric constant of no more than 12 to 1 KHz or higher frequency, a thermal expansion coefficient in the fiber direction of no more than 14 ppm/°C, and a thermal conductivity in the fiber direction of at least 5 W/m°K, and a thermal conductivity transverse to the fiber direction of at least 0.3 W/m°K.

Claim 3

A composite ply comprised of a planarly oriented plurality of high thermal conductivity, low thermal exansion coefficient, moderately low dielectric constant crystalline ceramic fibers embedded in a low dielectric constant resin matrix, the composite having an out-of-plane dielectric constant of no more than 12 to 1 KHz or higher frequency, a quasi-isotropic in-plane thermal expansion coefficient of no more than 14 ppm/°C, and a thermal conductivity in the plane of the ply of at least 5 W/m°K, and out of the plane of the ply of at least 0.3 W/m°K.

Claim 4

A composite ply comprised of a planarly oriented plurality of high thermal conductivity, low thermal exansion coefficient, moderately low dielectric constant crystalline ceramic fibers embedded in a low dielectric constant resin matrix, the composite having an out-of-plane dielectric constant of no more than 12 to 1 KHz or higher frequency, a quasi-isotropic in-plane thermal expansion coefficient of no more than 14 ppm/°C, and a thermal conductivity in the plane of the ply of at least 5 W/m°K, and out of the plane of the ply of at least 0.3 W/m°K.

Claim 5

The composite ply of Claim 1 or Claim 2 wherein the thermal conductivity of said crystalline ceramic fibers is at least 8 W/m°K.

Claim 6

The composite ply of Claim 1 or Claim 2 wherein the thermal condictivity of said crystalline ceramic fibers is at least 25 W/m°K.

Claim 7

The composite ply of Claim 1 or Claim 2 wherein the dielectric constant of said crystalline ceramic fibers is no more than 80 (measured at room temperature and at 1 KHz or higher frequency).

Claim 8

The composite ply of Claim 1 or Claim 2 wherein the dielectric constant of said crystalline ceramic fibers is no more than 50 (measured at room temperature and at 1 KHz or higher frequency).

Claim 9

The composite ply of Claim 1 or Claim 2 wherein the dielectric constant of said crystalline ceramic fibers is no more than 12 (measured at room temperature and at 1 KHz or higher frequency).

Claim 10

The composite ply of Claim 1 or Claim 2 wherein the coefficient of thermal expansion of said crystalline ceramic fibers is no more than 14 ppm/°C from 50 to 200°C.

Claim 11

The composite ply of Claim 1 or Claim 2 wherein the coefficient of thermal expansion of said crystalline ceramic fibers is no more than 9 ppm/°C from 50 to 200°C.

Claim 12

The composite ply of Claim 1 or Claim 2 wherein the dielectric constant of said resin matrix is no more than 5 (measured at room temperature and at 1 KHz or higher frequency).

Claim 13

The composite ply of Claim 1 or Claim 2 wherein the ceramic fibers comprise at least 30 volume per cent of the composite.

Claim 14

The composite ply of Claim 1 or Claim 2 wherein the ceramic fibers comprise at least 45 volume per cent of the composite.

Claim 15

The composite ply of Claim 1 or Claim 2 wherein the ceramic fibers are composed of a pure, dense, crystalline ceramic material selected from the group of alumina, aluminum nitride, silicon carbide, alpha quartz, beryllium oxide, boron nitride, silicon nitride, magnesium oxide, and diamond and mixtures thereof.

Claim 16

The composite ply of Claim 13 wherein said ceramic material is further mixed with one or more non-ceramic fiber materials.

Claim 17

The composite ply of Claim 1 or Claim 2 wherein the ceramic fibers are composed of alpha alumina.

Claim 18

The composite ply of Claim 1 or Claim 2 wherein the ceramic fibers are composed of alpha alumina which is at least 97% pure.

Claim 19

The composite ply of Claim 1 or Claim 2 wherein the ceramic fibers are composed of aluminum nitride.

Claim 20

The composite ply of Claim 1 or Claim 2 wherein the fibers are substantially continuous along one axis within the ply.

Claim 21

The composite ply of Claim 1 or Claim 2 wherein the fibers are no more than 25 microns in diameter.

Claim 22

The composite ply of Claim 1 wherein the ceramic fibers are aligned parallel to one another in the plane of the ply.

Claim 23

The ply of Claim 2 wherein the ceramic fibers are in random in-plane array.

Claim 24

The ply of Claim 2 wherein the ceramic fibers are in a woven array.

Claim 25

The ply of Claim 2 wherein the ceramic fibers are in a non-woven array.

Claim 26

A laminate comprising the composite ply of Claim 1 laminated with at least one additional composite ply also having a plurality of fibers aligned parallel to one another in the plane of the additional ply, the aligned fibers in the first ply and in the additional plies being angularly displaced from one another by a predetermined amount to maintain in-plane rotational symmetry of 2 or greater and out-­of-plane mirror symmetry.

Claim 27

The laminate of claim 24 comprising at least six plies wherein the fibers of each ply are in collimated array, and are oriented with predetermined angular symmetry to achieve quasi-isotropic in-plane physical properties.

Claim 28

The laminate of Claim 25 wherein said predetermined angular symmetry is 0°, +60°, -60°, -60°, +60°, 0° with respect to an arbitrarily designated 0° axis.

Claim 29

The laminate of Claim 25 wherein said predetermined angular symmetry is 0°, +45°, -45°, 90°, 90°, -45°, +45°, 0° with respect to an arbitrarily designated 0° axis.

Claim 30

The composite ply of Claim 1 or Claim 2 wherein the resin is selected from the group of polyimides, polyamides, epoxies, polyetherimides, polyamide-imides, fluoropolymers, polyarylates, polyetherketones, polysulfones, polyphenylene sulfides, bismaleimide resins, phenolic resins polyesters, polybutadiene, polyetheretherketones, polyetherketoneketones, cyanate esters, and modified resins and copolymers of these.

Claim 31

The composite poly of Claim 28 wherein the resin matrix is filled with a predetermined volume percentage of a particulate filler material.

Claim 32

The composite ply of Claim 1 or Claim 2 wherein the resin is a polyimide.

Claim 33

The composite ply of Claim 1 or Claim 2 wherein the resin is an epoxy.

Claim 34

An electronic substrate comprised of the composite of Claim 1 or Claim 2 or Claim 24 and, disposed in preselected patterns on at least one ply surface thereof, an electrically conductive material forming an electric circuit, the composite being adapted to rapidly conduct heat from any source of heat in the circuit to the surrounding area of the ply and through the thickness of the ply to the opposite face.

Claim 35

The electronic substrate of Claim 32 wherein the fibers contained in the ply are composed of alpha alumina.

Claim 36

The electronic substrate of Claim 32 wherein the fibers contained in the ply are composed of aluminum nitride.

Claim 37

The electronic substrate of Claim 32 wherein the resin in the ply is a polyimide.

Claim 38

The electronic substrate of Claim 32 wherein the resin in the ply is an epoxy resin.

Claim 39

The method of making the composite ply of Claim 1 comprising the steps of: a. positioning said ceramic fibers in a predetermined array; b. coating or impregnating said ceramic fiber array with a hardenable liquid polymer such that the polymer coating on the individual fibers forms bonding surfaces between contiguous fibers; and c. hardening said polymer to effect bonding between contiguous fibers such that less than 5 volume per cent voids are formed.

Claim 40

The method of making the composite laminate of Claim 24 comprising the steps of: a. positioning said ceramic fibers in a predetermined array; b. coating or impregnating said ceramic fiber array with a heat- hardenable liquid polymer such that the polymer coating on the individual fibers forms bonding surfaces between contiguous fibers; c. hardening said polymer to effect bonding between contiguous fibers to make a ply such that less than 5 volume per cent voids are formed; d. forming the laminate by overlaying a plurality of plies in which the fibers are oriented in a predetermined array such that the polymer coating on the fibers forms bonding surfaces between contiguous fibers; and e. treating the laminate of step d. to effect hardening of the liquid polymer and bonding between contiguous fibers such that less than 5 volume per cent voids are formed

Claim 41

A composite suitable for use as a printed circuit board comprising the ply of Claim 1 or Claim 2 having a thin layer of metal bonded to at least one surface thereof.

Claim 42

A composite suitable for use as a printed circuit board comprising the laminate of Claim 24 having a thin layer of metal bonded to at least one surface of one ply thereof.

Claim 43

The composite of Claim 38 wherein said metal is copper.

Claim 44

The composite of Claim 39 wherein said metal is copper.

Claim 45

A method of making the composite of Claim 38 comprising the steps of: a. positioning said ceramic fibers in an array; b. coating or impregnating said ceramic fiber array with a hardenable liquid polymer such that the polymer coating on the individual fibers forms bonding surfaces between contiguous fibers such that less than 5 volume per cent voids are formed; c. placing a metal sheet adjacent to at least one surface of said polymer-coated fiber array; and d. hardening said polymer to effect bonding between contiguous fibers and said metal sheet such that less than 5 volume per cent voids are formed.

Claim 46

The method of making the composite of Claim 38 comprising the steps of: a. positioning said ceramic fibers in an array; b. coating or impregnating said ceramic fiber array with a hardenable liquid polymer such that the polymer coating on the individual fibers forms bonding surfaces between contiguous fibers and less than 5 volume per cent voids are formed; c. adding additional liquid polymer to at least one surface of said array; d. placing a metal sheet adjacent to at least one surface of said polymer-coated fiber array; and e. hardening said polymer to effect bonding between contiguous fibers and said metal sheet such that less than 5 volume per cent voids are formed.

Claim 47

The method of Claim 42 or Claim 43 wherein said metal sheet is precoated with said polymer.

Claim 48

A method of making the composite of Claim 39 comprising the steps of: a. positioning said ceramic fibers in an array; b. coating or impregnating said ceramic fiber array with a heat-hardenable liquid polymer such that the polymer coating on the individual fibers forms bonding surfaces between contiguous fibers; c. hardening said polymer to effect bonding between contiguous fibers to make a ply such that less than 5 volume per cent voids are formed; d. forming the laminate by overlaying a plurality of plies in which the fibers are oriented in a predetermined array such that the polymer coating on the fibers forms bonding surfaces between contiguous fibers; e. placing a metal sheet adjacent to at least one surface of said laminate; and f. heating the laminate of step e. to effect hardening of the liquid polymer and bonding between contiguous fibers and said metal sheet such that less than 5 volume percent voids are formed.

Claim 49

The ply of Claim 1 or Claim 2 wherein at least one surface is coated with additional resin to provide a smooth surface in order to enhance photo-­process resolution of circuit patterns and microwave properties of the ply.

Claim 50

The ply of Claim 46 wherein said smooth surface contains no nonuniformities of greater than 20 microinches in height.

Claim 51

The composite of Claim 39 wherein at least one of the outer surfaces is coated with additional resin to provide a smooth surface in order to enhance photo-process resolution of circuit patterns and microwave properties of the composite.