Methods for simultaneously brazing a ferrule and lead pins

• US 9,138,821 B2
• Filed: 04/24/2014
• Issued: 09/22/2015
• Est. Priority Date: 01/17/2014
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Brosnan, William M., Iyer, Rajesh V., Johnstone, George C., Tettemer, Susan A., Thom, Andrew J.
• Primary Examiner(s): STONER, KILEY SHAWN
• Application Number:
  US14/260,401
• Publication Number:
  US 20150202706A1
• Time in Patent Office: 516 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B23K 1/0016 Brazing of electronic components
• CPC Class Codes: B23K 1/008 Soldering within a furnace B23K1/012 takes precedence
• CPC Class Codes: B23K 2101/38 Conductors
• CPC Class Codes: B23K 3/0623 for shaped solder piece feeding, e.g. preforms, bumps, balls, pellets, droplets
• CPC Class Codes: B23K 37/0426 Fixtures for other work
• CPC Class Codes: B23K 37/0435 Clamps
• CPC Class Codes: H01G 4/35 Feed-through capacitors or anti-noise capacitors
• CPC Class Codes: H01R 4/027 comprising means for positioning or holding the parts to be soldered or welded
• CPC Class Codes: H01R 43/0249 for simultaneous welding or soldering of a plurality of wires to contact elements
• CPC Class Codes: H01R 43/20 for assembling or disassembling contact members with insulating base, case or sleeve

Abstract

A lead pin fixture is used to align and hold lead pins in place for brazing lead pins to metal contact pads of a ceramic insulator and brazing a ferrule to the ceramic insulator in a single step.

Claims

1. A method for simultaneously brazing a ferrule and lead pins comprising:

providing a feedthrough comprising a ceramic insulator having at least one conductive via, the at least one via having a contact pad on a surface of the ceramic insulator, a ferrule surrounding the ceramic insulator and a ferrule braze preform around the ceramic insulator and between the ferrule and the ceramic insulator;

providing at least one lead pin having a head at a proximal end and having a distal end, and a lead pin braze preform attached to the head;

providing a freestanding lead pin fixture comprising a plurality of lead pin fixture holes through the lead pin fixture, the holes configured to accept insertion of the at least one lead pin, the freestanding lead pin fixture configured to be placed over the feedthrough such that the at least one fixtured lead pin and attached braze preform are aligned and in contact with the contact pad on the surface of the ceramic insulator;

inserting the at least one lead pin into the at least one lead pin fixture holes;

placing said freestanding lead pin fixture over the feedthrough such that the at least one fixtured lead pin and attached braze preform are aligned and in contact with the contact pad on the surface of the ceramic insulator to form a feedthrough assembly; and

heating the feedthrough assembly at a temperature and for a time sufficient to form brazed joints between the ferrule and the ceramic insulator and the at least one lead pin and the contact pad.

2. The method of claim 1 further comprising holding the distal end of the at least one lead pin in place before placing said freestanding lead pin fixture over the feedthrough.

3. The method of claim 1 wherein the feedthrough assembly is heated at a temperature of about 1000-1150°

C.

4. The method of claim 2 wherein the distal end of the at least one lead pin is held in place by a clamp.

5. An assembly comprising:

a lead pin fixture comprising a feedthrough insertion cutout and a plurality of lead pin fixture holes through the lead pin fixture, and at least one lead pin fit within one of the plurality of lead pin fixture holes, the at least one lead pin having a proximate end of the lead pin; and

a feedthrough fitted within the feedthrough insertion cutout of the lead pin fixture and comprising a ceramic insulator having at least one conductive via, the at least one via having a contact pad on a surface of the ceramic insulator, a lead pin braze preform between and contacting the contact pad and the proximate end of the at least one lead pin, a ferrule surrounding the ceramic insulator and a ferrule braze preform around the ceramic insulator and between the ferrule and the ceramic insulator.

6. The assembly of claim 5 wherein the at least one lead pin has a lead pin head at the proximate end of the lead pin.

7. The assembly of claim 5 wherein the at least one lead pin has a distal portion and a distal end, wherein the distal portion and the distal end of the at least one lead pin extends out of the lead pin fixture.

8. The assembly of claim 7 further comprising a clamp position at a point along the distal portion of the at least one lead pin.

9. A method for simultaneously brazing a ferrule and lead pins comprising

providing a feedthrough comprising a ceramic insulator having at least one conductive via, the at least one via having a contact pad on a surface of the ceramic insulator, a lead pin braze preform on the contact pad, a ferrule surrounding the ceramic insulator and a ferrule braze preform around the ceramic insulator and between the ferrule and the ceramic insulator;

providing at least one lead pin having a head at a proximal end and having a distal end;

providing a freestanding lead pin fixture comprising a plurality of lead pin fixture holes through the lead pin fixture, the holes configured to accept insertion of the at least one lead pin, the freestanding lead pin fixture configured to be placed over the feedthrough such that the at least one fixtured lead pin and braze preform are aligned and in contact with the contact pad on the surface of the ceramic insulator;

inserting the at least one lead pin into the at least one lead pin fixture holes;

placing said freestanding lead pin fixture over the feedthrough such that the head of the at least one fixtured lead pin is aligned and in contact with the braze preform on the contact pad on the surface of the ceramic insulator to form a feedthrough assembly; and

heating the feedthrough assembly at a temperature and for a time sufficient to form brazed joints between the ferrule and the ceramic insulator and the at least one lead pin and the contact pad.

10. The method of claim 9 further comprising holding the distal end of the at least one lead pin in place before placing said freestanding lead pin fixture over the feedthrough.

11. The method of claim 10 wherein the distal end of the at least one lead pin is held in place by a clamp.

12. The method of claim 9 wherein the feedthrough assembly is heated at a temperature of about 1000-1150°

C.