Dielectric substrate comprising unsintered polytetrafluoroethylene and methods of making the same

Patent metadata

Field	Value
Publication number	US-2017145182-A1
Application number	US-201615352096-A
Country	US
Kind code	A1
Filing date	Nov 15, 2016
Priority date	Nov 25, 2015
Publication date	May 25, 2017
Grant date	—

Abstract

In an embodiment, a dielectric substrate comprises an unsintered polytetrafluoroethylene; and a high dielectric constant filler, wherein the dielectric constant of the high dielectric constant filler is greater than or equal to 35; wherein the dielectric substrate has a specific gravity of greater than or equal to 90% of a calculated theoretical density of the dielectric substrate, wherein the theoretical specific gravity is calculated based on a measured specific gravity of the high dielectric constant filler, the specific gravity of the unsintered polytetrafluoroethylene, and the relative weight fractions of the unsintered polytetrafluoroethylene and the high dielectric constant filler; and wherein the dielectric substrate has a dielectric constant of greater than or equal to 11.5 as determined at a frequency of 10 GHz.

First claim

1 . A dielectric substrate comprising:
an unsintered polytetrafluoroethylene; and a high dielectric constant filler, wherein the dielectric constant of the high dielectric constant filler is greater than or equal to 35; wherein the dielectric substrate has a specific gravity of greater than or equal to 90% of a calculated theoretical density of the dielectric substrate, wherein the theoretical specific gravity is calculated based on a measured specific gravity of the high dielectric constant filler, the specific gravity of the unsintered polytetrafluoroethylene, and the relative weight fractions of the unsintered polytetrafluoroethylene and the high dielectric constant filler; and wherein the dielectric substrate has a dielectric constant of greater than or equal to 11.5 as determined at a frequency of 10 GHz.

2 . The dielectric substrate of claim 1 , wherein the unsintered polytetrafluoroethylene comprises a polytetrafluoroethylene homopolymer.

3 . The dielectric substrate of claim 1 , wherein the unsintered polytetrafluoroethylene comprises a trace modified polytetrafluoroethylene homopolymer, wherein the trace modified polytetrafluoroethylene homopolymer comprises less than 1 wt % of a repeat unit derived from a co-monomer other than tetrafluoroethylene based on the total weight of the trace modified polytetrafluoroethylene homopolymer.

4 . The dielectric substrate of claim 1 , wherein the unsintered polytetrafluoroethylene polymer is made by emulsion polymerization.

5 . The dielectric substrate of claim 1 , wherein the high dielectric constant filler has a dielectric constant of greater than or equal to 100.

6 . The dielectric substrate of claim 1 , wherein the high dielectric constant filler comprises titanium dioxide.

7 . The dielectric substrate of claim 1 , wherein the high dielectric constant filler comprises titanium dioxide, calcium titanate, strontium titanate, barium titanate, or a combination comprising at least one of the foregoing.

8 . The dielectric substrate of claim 1 , wherein the dielectric substrate comprises 50 to 85 wt % of the high dielectric constant filler based on the total weight of the dielectric substrate.

9 . The dielectric substrate of claim 1 , wherein the dielectric substrate comprises 15 to 50 wt %, of the unsintered polytetrafluoroethylene based on the total weight of the dielectric substrate.

10 . The dielectric substrate of claim 1 , wherein the dielectric substrate consists essentially of the unsintered polytetrafluoroethylene and the high dielectric constant filler.

11 . The dielectric substrate of claim 1 , wherein the specific gravity is at least 95% of the theoretical specific gravity of the dielectric substrate.

12 . The dielectric substrate of claim 1 , wherein the dielectric constant of the dielectric substrate is greater than or equal to 12.

13 . An article comprising the dielectric substrates of claim 1 .

14 . The article of claim 13 , wherein the article is a mobile phone, a tablet, or a laptop.

15 . The article of claim 13 , wherein the article is an antenna.

16 . A method of making the dielectric substrate of claim 1 , comprising:
forming a mixture comprising the unsintered polytetrafluoroethylene, the high dielectric constant filler, and a lubricant; forming a preform from the mixture; calendering the preform to form a sheet; heating the sheet to remove the lubricant at a heating temperature that is below a melting temperature of the unsintered polytetrafluoroethylene; and dry calendering the sheet after the heating to form the dielectric substrate.

17 . The method of claim 16 , wherein the sheet after the heating comprises less than or equal to 1 wt % or 0 to 0.01 wt % of the lubricant based on the total weight of the sheet.

18 . The method of claim 16 , wherein the heating temperature is less than or equal to 300° C.

19 . The method of claim 16 , wherein the forming the preform comprises extruding the mixture.

20 . The method of claim 16 , further comprising biaxially calendering the sheet after the calendering at an angle of 45 to 135° from an initial calendering direction.

Assignees

• Rogers Corp

Inventors

• Horn Iii Allen F
• Caisse Christopher J
• Lafrance Patricia A

Classifications

• B29K2027/18

  PTFE, i.e. polytetrafluoroethylene {, e.g. ePTFE, i.e. expanded polytetrafluoroethylene} · CPC title

• H01Q9/0485

  Dielectric resonator antennas · CPC title

• C08K3/22 Primary

  of metals · CPC title

• B29C43/24

  Calendering · CPC title

• G06F1/1613

  for portable computers (cooling arrangements therefor G06F1/203; constructional details or arrangements for pocket calculators, electronic agendas or books G06F15/0216; constructional details of portable telephone sets: with several bodies H04M1/0202) · CPC title