Subassembly for a microwave connector and method for making it

• US 5,067,912 A
• Filed: 11/03/1987
• Issued: 11/26/1991
• Est. Priority Date: 11/03/1987
• Status: Expired due to Fees

• Current Assignee: The Whitaker Corporation (Meggitt PLC)
• Original Assignee: M/A-Com Adams-Russell, Inc.
• Inventors: Smith, Kenneth L., Bickford, Wayne F.
• Primary Examiner(s): PIRLOT, DAVID
• Application Number:
  US07/116,473
• Time in Patent Office: 1,484 Days
• Field of Search: 439/578-585, 439/675, 439/736, 333/254-260, 333/261, 333/245, 156/158, 156/244.11-244.15, 29/868, 29/856, 29/858, 29/841, 29/848, 29/883, 29/885, 29/631, 29/842, 264/262, 264/272.11, 264/272.12, 264/272.13, 264/274, 264/277
• US Class Current: 439/578
• CPC Class Codes: H01R 24/40 specially adapted for high frequency
• CPC Class Codes: H01R 43/20 for assembling or disassembling contact members with insulating base, case or sleeve
• CPC Class Codes: Y10T 29/49147 Assembling terminal to base

Abstract

A subassembly for microwave structure such as a connector is described. An insulator for spacing of at least one center conductor is formed of PTFE (polytetrafluoroethylene) and effectively bonded to at least one center conductor to be used in the connector. The PTFE may be bonded to the conductor by employing an intermediate layer of FEP (fluorinated ethylene-propylene) that can be bonded to the center conductor. Bonding of the components into an integral subassembly is done in a single step involving heating and pressurizing a pre-assembly in a mold to a sufficient amount and for a sufficient time to provide an acceptably strong bond. Superior electrical characteristics such as a low SWR and insertion loss are achieved in captivated and/or sealed connectors. A good seal is achieved between the insulator and the outer conductor by forming an undercut in the latter, filling it with silicone grease and enabling a temporarily mechanically-collapsed bead on the insulator to expand into the undercut.

Claims

1. A method for making a conductor subassembly comprising the steps of:

forming a preassembly of a metal conductor placed adjacent a first layer of a first fluoroplastic material and with the first layer placed adjacent a second layer formed of a second fluoroplastic material;

said first fluoroplastic material being more readily bondable to said conductor than the second fluoroplastic material and being bondable to said second fluoroplastic material; and

applying heat and pressure to the preassembled conductor, and the first and second layer in a sufficient amount and for a sufficient time to bond the conductor to the first layer and the first layer to the second layer to form an integral subassembly.

2. The method as claimed in claim 1 and further comprising the step of:

thoroughly cleaning the metal conductor and said first and second layers of fluoroplastic materials.

3. The method as claimed in claim 1 and further including the steps of:

forming a central conductor, a sleeve of said first fluoroplastic material and shaped to snugly surround the central conductor and a cylindrical insulator formed of said second fluoroplastic material and having a through bore sized to snugly fit around said sleeve.

4. The method as claimed in claim 1 wherein the first fluoroplastic material is fluorinated ethylene-propylene and said second fluoroplastic material is polytetrafluoroethylene.

5. The method as claimed in claim 4 wherein the heat and pressure applying steps comprise respectively

applying heat in an amount so as to establish a temperature in the range from about 730°

F. to about 750°

F.; and

applying pressure at a level in the range from about 10,500 psi to about 16,500 psi.

6. The method as claimed in claim 5 wherein the assembling step includes the steps of:

first heating the preassembly to said desired temperature and then applying said pressure while maintaining the temperature.

7. A microwave structure comprising an integral subassembly formed of a center conductor for a coaxial connector, a first insulative sleeve layer formed of an FEP fluoroplastic material with said sleeve bonded to the conductor and a second cylindrical insulative layer of a second PTFE fluoroplastic material having a through bore sized to snugly enclose the sleeve and being sized to form an insulator spacer for the center conductor in the coaxial connector;

wherein the coaxial connector has a cylindrical outer conductor having a bore sized to snugly receive the second insulative layer and having an inwardly-facing annular recess, said second insulative layer being provided with a collapsible externally projecting annular bead sized to fit inside the recess and engage walls thereof.

8. A microwave structure comprising an integral subassembly formed of a center conductor for a coaxial connector, a first insulative sleeve layer formed of a FEP fluoroplastic material with said sleeve bonded to the conductor and a second cylindrical insulative layer of a second PTFE fluoroplastic material having a through bore sized to snugly enclose the sleeve and being sized to form an insulator spacer for the center conductor in the coaxial connector;

wherein the first fluoroplastic insulative layer surrounds the conductor and is bonded thereto at one side of the conductor and wherein the second fluoroplastic material insulative layer surrounds the conductor at another side of the conductor and is bonded to a side of the first fluoroplastic material.

10. The microwave coaxial structure as claimed in claim 8 wherein the silicone material is silicone grease.

11. The microwave coaxial structure as claimed in claim 10 wherein said conductor is an outer conductor of a microwave coaxial connector.

9. In a microwave structure having a conductor, the improvement comprising:

an annular undercut formed in the conductor;

an insulator formed of PTFE and having an annular bead sized to expand into the undercut after mechanical collapse to fit the insulator to the conductor; and

a silicone material placed inside the undercut to form a seal between the insulator and said conductor.