Technique for welding dissimilar metals

• US 5,571,146 A
• Filed: 10/31/1995
• Issued: 11/05/1996
• Est. Priority Date: 10/31/1995
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Campbell, Arthur A., Jones, Stephen M., Pennala, Jeffrey L.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US08/550,907
• Time in Patent Office: 371 Days
• Field of Search: 607/36-38
• US Class Current: 607/37
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: A61N 1/3752 Details of casing-lead connections
• CPC Class Codes: A61N 1/3754 Feedthroughs
• CPC Class Codes: B23K 2103/05 Stainless steel

Abstract

For an implantable medical devices, a system is provided for welding electrically conductive ribbon, typically stainless steel, to electrically conductive wire, typically platinum, the melting point of steel being substantially lower than that of platinum. An aperture is formed in the ribbon having an opening smaller than that of the wire. The ribbon is engaged with the wire such that the aperture is generally coextensive with the wire. Thereupon, a pulse laser beam is directed transversely of the ribbon through the aperture and onto the wire to simultaneously melt the wire and the ribbon and to create a homogeneous mix of the molten steel and platinum in the region surrounding the aperture. Thereafter, operation of the laser beam is discontinued to allow solidification and thereby achieve a welded connection between the ribbon and the wire.

Claims

1. An implantable stimulating device for stimulating a patient'"'"'s heart, comprising:

a battery;

pulse generating means, coupled to the battery, for generating stimulation pulses to the patient'"'"'s heart;

a hermetically sealed housing having an interior region containing the battery and the pulse generating means and an exterior region;

a plurality of connector blocks disposed adjacent the exterior region of the housing;

at least one stimulation lead having a proximal end secured to the connector blocks and a distal end for implantation into the patient'"'"'s heart;

a plurality of feedthrough terminal pins, each having a longitudinal axis, extending through the housing for connecting the pulse generating means to the connector blocks, the plurality of feedthrough terminal pins being made of a first material having a first melting point;

a plurality of conductor ribbons extending between respective ones of the connector blocks and the feedthrough terminal pins, the plurality of conductor ribbons being made of a second material having a second melting point, the first and second materials being dissimilar, the first and second melting points being substantially different, each conductor ribbon extending to a terminal end proximate an associated one of the terminal pins, the terminal end having a transversely extending aperture therethrough with an opening smaller than a transverse dimension of the terminal pin, the terminal end lying in a plane parallel with and proximate to the associated one of the terminal pins and such that the center of the aperture in the terminal end of the conductor ribbon is generally aligned with the longitudinal axis of the terminal pin, such that a laser beam directed transversely of the conductor ribbon through the aperture therein impinges on the terminal pin to simultaneously melt the terminal pin and the conductor ribbon in the region of the aperture and create a homogenous mix of the first material with the second material in the region surrounding the aperture which, when solidified, achieves a welded connection between the conductive ribbon and the terminal pin without the formation of cracks and voids in the welded connection; and

encapsulation means, attached to the housing, for encapsulating the plurality of connector blocks and the plurality of conductor ribbons therein, the encapsulation means further having at least one channel for receiving at least one stimulating lead therein.

2. An implantable stimulating device, as set forth in claim 1:

wherein the first melting point is substantially higher than the second melting point.

3. An implantable stimulating device, as set forth in claim 2:

wherein the second material is stainless steel; and

wherein the first material is platinum.

4. An implantable stimulating device, as set forth in claim 3:

wherein each stainless steel conductor ribbon has opposed first and second edges and a terminal edge joining the first and second edges and is approximately 0.020 inches wide by approximately 0.006 inches thick;

wherein the aperture in each stainless steel conductor ribbon has a diameter of approximately 0.008 inches; and

wherein each platinum terminal pin has a diameter of approximately 0.012 inches.

5. An implantable stimulating device, as set forth in claim 1:

wherein the second material is stainless steel having a melt temperature of 1,398°

C.; and

wherein the first material is platinum having a melt temperature 1,773°

C.