Dielectric material and method of making the dielectric material

• US 4,518,737 A
• Filed: 02/17/1982
• Issued: 05/21/1985
• Est. Priority Date: 12/26/1978
• Status: Expired due to Fees

• Current Assignee: Rogers Corporation (Rogers Communications Inc.)
• Original Assignee: Rogers Corporation (Rogers Communications Inc.)
• Inventors: Traut, G. Robert
• Primary Examiner(s): MARQUIS, MELVYN I
• Application Number:
  US06/349,466
• Time in Patent Office: 1,189 Days
• Field of Search: 524/413, 524/444, 524/435, 524/493, 524/494, 252/518, 252/519, 252/520, 264/122
• US Class Current: 524/413
• CPC Class Codes: B29C 67/02 Moulding by agglomerating B29C67/20 takes precedence
• CPC Class Codes: B29C 70/025 with particular filler
• CPC Class Codes: B29C 70/88 characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced
• CPC Class Codes: B29K 2105/0064 Latex, emulsion or dispersion
• CPC Class Codes: B29K 2105/007 Paste, dough
• CPC Class Codes: B29K 2105/12 of short lengths, e.g. chopped filaments, staple fibres or bristles
• CPC Class Codes: B29K 2105/122 microfibres or nanofibers
• CPC Class Codes: B29K 2105/16 Fillers
• CPC Class Codes: B29K 2995/0006 Dielectric
• CPC Class Codes: B29L 2007/002 Panels; Plates; Sheets
• CPC Class Codes: H01B 3/445 from vinylfluorides or other fluoroethylenic compounds
• CPC Class Codes: H01B 3/48 fibrous materials fibre-reinforced plastics H01B3/47
• CPC Class Codes: H05K 1/034 containing halogen
• CPC Class Codes: H05K 1/0366 reinforced, e.g. by fibres, fabrics H05K1/036 takes precedence
• CPC Class Codes: H05K 1/0373 containing additives, e.g. fillers H05K1/036 takes precedence
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 2201/0116 Porous, e.g. foam

Abstract

A method of making a dielectric material comprising blending in a polymer dispersion, a particulate filler material having a high dielectric constant and microfibrous material to form a slurry of polymer, filler, and fiber. A flocculant is added to the slurry to agglomerate the polymer particles, the filler particles, and the microfibers to produce a dough-like material. The dough-like material is formed into a desired shape and then subjected to heat and pressure to densify the dielectric material.

Claims

1. A non-porous dielectric sheet material wherein the dielectric constant is substantially isotropic, said sheet material comprising a fluorinated polymer binding selected from the group consisting of polytetrafluoroethylene, fluorinated poly (ethene-co-propene), polyolefins, polyacrylates, polystyrenes and poly (vinylidene fluoride), a ceramic filler in particulate form having an average particle diameter of between about 1 to 20 micrometers and non-conductive inorganic microfibers having an average diameter less than 2 micrometers selected from the group consisting of glass, aluminum silicate, potassium titanate, quartz and zirconia, the ratio of the weight of fibers to total non-filler being in the range of 0.07 to 0.20 and the filler comprising between 10% and 75% by weight of the dielectric material.

2. The dielectric material of claim 1 having a water absorption less than 0.5 percent.

3. The dielectric material of claim 1 wherein said ceramic filler is selected from the group comprising titania, aluminia, zirconia, ground quartz, amorphous or crystalline silica and ferrites.

4. The sheet material of claim 1 wherein said polymer binder comprises polytetrafluoroethylene and wherein said ceramic filler comprises titania, said titania comprising at least 60% by weight of the dielectric material and having an average particle size of between about 1 to 20 micrometers.

5. The material of claim 3 wherein said microfibers are glass and comprise more than 3.00% and less than 5.00% by weight of the dielectric material.

6. The material of claim 4 wherein said microfibers are glass and comprise more than 3.00% and less than 5.00% by weight of the dielectric material.

7. A method of making a non-porous isotropic dielectric sheet material which has desirable strain relief characteristics in the X and Y directions, a substantially isotropic dielectric constant and a water absorption less than 0.5% comprising the steps of:

mixing a dispersion of fluorinated polymer selected from the group consisting of polytetrafluoroethylene, flourinated poly (ethene-co-propene), polyolefins, polyacrylates, polystyrenes, and poly (vinylidene flouride) particles with a dielectric filler material in particulate form and nonconductive inorganic microfibers selected from the group consisting of glass, aluminum silicate, quartz, zirconia and potassium titanate to form a slurry, the slurry comprising enough filler and fibers to obtain in the final product between 10% and 75% by weight of the filler and between 7% and 20% fibers of the total non-filler content;

agglomerating the polymer particles, the ceramic filler particles and the microfibes to provide a mass of dielectric material;

shaping said mass; and

subjecting the shaped mass to heat and pressure to densify the dielectric material.

8. The method of claim 7 wherein the step of mixing further comprises:

adding a ceramic filler having an average particle size of between about 1 to 20 micrometers and between 3% and 5% by weight of glass fibers to an aqueous dispersion of polytetrafluoroethylene.