Method and apparatus for laser welding incorporating galvanometer delivery

• US 20060144827A1
• Filed: 12/30/2004
• Published: 07/06/2006
• Est. Priority Date: 12/30/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Papenfuss, Jason T., Buendorf, David J.
• Granted Patent: US 7,763,827 B2
• Time in Patent Office: Days
• US Class Current: 219/121.640
• CPC Class Codes: B23K 26/22 Spot welding
• CPC Class Codes: B23K 26/24 Seam welding

Abstract

Methods and systems for laser welding using a galvanometer to deliver laser energy in a multiple point sequence for high-speed and low-temperature welding of batteries, capacitors, medical devices, and related medical device components or the like.

Claims

1. A method of laser welding to form a weld seam along a junction between members suitable for use as part of an implantable medical device, comprising:

defining a weld path along the junction;

locating a plurality of initial welding locations spaced along the weld path;

delivering a first sequence of pulses of laser beam energy, each pulse in the first sequence of pulses being directed to one of the initial welding locations to form a first sequence of weld points of the members at the initial welding locations; and

delivering successive sequences of pulses of laser beam energy, the pulses in each successive sequence of pulses each being directed to a weld point located along the weld path an incremental distance from one of the existing weld points to form successive sequences of weld points of the members, the sequences continuing until the weld points form a generally continuous weld seam of the members along the weld path.

2. The laser welding method of claim 1, wherein the weld points formed by each sequence of pulses are spaced sufficiently along the weld path to distribute heat generated from the welding generally evenly along the weld path.

3. The laser welding method of claim 1, wherein the weld points formed in any one successive sequence are directly adjacent to the weld points formed in an immediately prior sequence to the any one successive sequence, and wherein each successive sequence of pulses forms the same number of weld points as formed in the first sequence of pulses.

4. The laser welding method of claim 1, wherein the successive sequences each form weld points progressively further from a respective one of the initial welding locations, and wherein the progression is in a weld direction, the weld direction being the same for each of the initial welding locations.

5. The laser welding method of claim 1, wherein successive sequences of pulses form weld points partially overlapping with existing weld points.

6. The laser welding method of claim 1, wherein the incremental distance is the same for each weld point in any one sequence of the successive sequences.

7. The laser welding method of claim 1, wherein the weld points formed are spot welds.

8. The laser welding method of claim 1, further comprising:

providing a mirror for reflecting the pulses of laser beam energy;

providing a galvanometer motor adapted to move the mirror to position the reflected laser beam along the weld path;

moving the mirror with the galvanometer motor to position the reflected laser beam along the weld path to deliver the first sequence of pulses of laser beam energy; and

moving the mirror with the galvanometer motor to position the reflected laser beam along the weld path to deliver the successive sequences of pulses of laser beam energy.

9. The method of laser welding of claim 8, further comprising a second mirror and a second galvanometer motor adapted to position the reflected laser beam in two dimensions along the weld path.

10. The method of laser welding of claim 8, further comprising a dynamic Z galvanometer adapted to provide a variable focal length laser beam, wherein the weld path is three-dimensional.

11. The method of laser welding of claim 8, wherein the members being welded are rotated about an axis.

12. The method of laser welding of claim 8, wherein the weld path is measured and stored in memory.

13. The method of laser welding of claim 12, wherein the number and location of initial welding locations along the weld path is automatically determined by a computer algorithm.

14. The method of laser welding of claim 8, wherein the members being welded form a hermetic seal along the weld path having greater than 25% overlap between adjacent weld points.

15. The method of laser welding of claim 14, wherein the amount of overlap between adjacent weld points is generally equal along the weld path, and wherein the incremental distance between the center of adjacent weld points is less than a radius of a weld point.

16. The method of laser welding of claim 8, wherein the members being welded form a housing for an implantable medical device (IMD).

17. The method of laser welding of claim 8, wherein a single pulsed laser source delivers laser energy to a plurality of weld paths for a plurality of members being welded located on a single fixture.

18. An implantable medical device (IMD) having a housing and a housing cover, the cover being hermetically sealed to the housing by a process that includes laser welding a hermetic seal weld, the laser welding process comprising:

defining a weld path having a weld direction;

locating a plurality of initial welding locations spaced along the weld path;

providing a pulsed laser beam;

providing a mirror for reflecting the pulsed laser beam;

providing a galvanometer motor adapted to move the mirror to position the reflected laser beam along the weld path;

moving the mirror with the galvanometer motor to position the reflected laser beam along the weld path to deliver a first sequence of pulses of laser beam energy, each pulse in the first sequence of pulses being directed to one of the initial welding locations to form a first sequence of weld points of the housing and cover at the initial welding locations; and

moving the mirror with the galvanometer motor to position the reflected laser beam along the weld path to deliver successive sequences of pulses of laser beam energy, the pulses in each successive sequence of pulses each being directed to a weld point located along the weld path an incremental distance from one of the existing weld points to form successive sequences of weld points of the housing and cover, the sequences continuing until the weld points form a generally continuous weld seam of the housing and cover along the weld path.

19. The IMD of claim 18, further comprising:

vision acquisition means to define the weld path on at least one of the housing and the cover;

motion controller means for locating the initial welding locations spaced along the weld path; and

controller means for coordinating the pulsed laser beam and the galvanometer motor in order to deliver the sequences of pulses.

20. A method of laser welding to form a weld seam along a junction between members, comprising:

defining a weld path having a weld direction;

providing a continuous wave laser beam;

providing a mirror for reflecting the continuous wave laser beam;

providing a galvanometer motor adapted to move the mirror to position the reflected laser beam along the weld path; and

moving the mirror with the galvanometer motor to deliver the reflected laser beam around the weld path until a substantially continuous weld seam is formed along the weld path.