Method for producing a cohesive laser bond connection and apparatus for forming a laser bond connection

Abstract

Methods for producing a cohesive laser bond connection, wherein, in a first method step, a bond element (2) made from copper is provided, in a second method step, a contact element (3) made from copper is provided, and, in a third method step, the bond element (2) and the contact element (3) are connected to one another in a joined fashion under the action of green laser radiation (1).

Claims

1. A method for producing a cohesive laser bond connection, wherein in a first method step, a bond element (2) formed from copper is provided, in a second method step, a contact element (3) made from copper is provided, in a third method step, the bond element (2) and the contact element (3) are connected to one another in a joined fashion under the action of green laser radiation with a laser beam (1), and in a fourth method step, after the third method step, severing the bond element (2) at a location that is not connected to the contact element (3).

2. The method according to the preceding claim 1, characterized in that the green laser radiation (1) has a wavelength of 532 nm.

3. The method according to claim 1, characterized in that the bond element (2) and the contact element (3) are immediately connected to one another.

4. The method according to claim 1, characterized in that the bond element (2) has a cross-sectional area arranged perpendicularly to a longitudinal direction of the bond element (2), wherein the cross-sectional area of the bond element (2) has a square, rectangular, or round shape.

5. The method according to claim 1, characterized in that the bond element (2) has a width arranged perpendicularly to a longitudinal direction of the bond element (2), wherein the width of the bond element has a value of less than 5 cm.

6. The method according to claim 1, characterized in that the bond element (2) has a width arranged perpendicularly to a longitudinal direction of the bond element (2), wherein the width of the bond element has a value of less than 1 cm.

7. The method according to claim 1, characterized in that the bond element (2) has a width arranged perpendicularly to a longitudinal direction of the bond element (2), wherein the width of the bond element has a value of less than 0.5 cm.

8. The method according to claim 1, characterized in that the contact element (3), provided in the second method step, is a voltage tap of a battery cell of a battery module or a monitoring system of a battery module.

9. The method according to claim 1, characterized in that the bond element (2) provided in the first method step has a first end and a second end, wherein the first end is connected in a joined fashion to a voltage tap of a battery cell and the second end is connected in a joined fashion to a voltage tap of a further battery cell, or wherein the first end is connected in a joined fashion to a voltage tap of a battery cell and the second end is connected to a monitoring system of the battery module.

10. The method according to claim 1, characterized in that, during the third method step, the action of the laser beam (1) is selected in a manner such that the evaporation temperature of copper is never exceeded.

11. The method according to claim 2, characterized in that the bond element (2) and the contact element (3) are immediately connected to one another.

12. The method according to claim 11, characterized in that the bond element (2) has a cross-sectional area arranged perpendicularly to a longitudinal direction of the bond element (2), wherein the cross-sectional area of the bond element (2) has a square, rectangular, or round shape.

13. The method according to claim 12, characterized in that the bond element (2) has a width arranged perpendicularly to a longitudinal direction of the bond element (2), wherein the width of the bond element has a value of less than 0.5 cm.

14. The method according to claim 13, characterized in that the contact element (3), provided in the second method step, is a voltage tap of a battery cell of a battery module or a monitoring system of a battery module.

15. The method according to claim 14, characterized in that the bond element (2) provided in the first method step has a first end and a second end, wherein the first end is connected in a joined fashion to a voltage tap of a battery cell and the second end is connected in a joined fashion to a voltage tap of a further battery cell, or wherein the first end is connected in a joined fashion to a voltage tap of a battery cell and the second end is connected to a monitoring system of the battery module.

16. The method according to claim 15, characterized in that, during the third method step, the action of the laser beam (1) is selected in a manner such that the evaporation temperature of copper is never exceeded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description.

(2) In the drawings

(3) FIG. 1 schematically shows the embodiment of a heat conduction welding method, and

(4) FIG. 2 schematically shows the realization of a deep welding method.

DETAILED DESCRIPTION

(5) It is possible using the method according to the invention to cohesively connect bond elements made from copper and contact elements made from copper by means of laser bonding.

(6) In this respect, FIG. 1 schematically shows the performance of a heat conduction welding method on which the method according to the invention is based.

(7) Here, as already described, a laser welding method or laser joining method is used for forming a connection, wherein the wavelength of the used laser beam lies in the range of green light and particularly preferably has a value of 532 nm.

(8) FIG. 1 shows here the used laser beam 1.

(9) FIG. 2 furthermore shows one of the two elements that are to be connected to one another, that is to say either a bond element 2 or a contact element 3.

(10) The action of the laser beam 1 is selected here such that the evaporation temperature of copper is not exceeded.

(11) This can be achieved for example by way of combining power and advancement of the laser beam 1 or the duration of their radiation with the laser beam 1.

(12) It is of course also possible to install suitable temperature controls, for example the installation of temperature sensors on the surface of the element to be connected.

(13) It is furthermore also possible to change the intensity of the laser beam 1 by way of targeted focusing.

(14) Consequently, evaporation of the copper is avoided, which is critical for heat conduction welding.

(15) The action of the laser beam 1 is furthermore selected here such that the copper material is locally melted.

(16) In FIG. 1, reference sign 41 denotes a melt zone in which the copper material is present in liquid form, and reference sign 42 denotes a melt zone in which the copper material exists in solid form.

(17) The second element (not shown in FIG. 1) of the two elements that are to be connected to one another, that is to say either a contact element or a bond element, is arranged here such that it is molten locally due to heat conduction alone, also referred to as conduction.

(18) Consequently, the two elements, that is to say a bond element and a contact element, can subsequently be connected to one another.

(19) To ensure there is sufficient area for the connection of the two joining partners, it is possible for example for larger areas to be connected to one another or for multiple connecting locations to be formed at different locations.

(20) It should also be noted at this point that FIG. 1 is merely intended to serve for the schematic illustration of heat conduction welding.

(21) For the geometry of the weld seam formed, any desired and producible shape can be used.

(22) FIG. 2 schematically shows a deep welding method known from the prior art.

(23) Again, a bond element 20 or a contact element 30 can be seen here as one of the two elements to be connected.

(24) A laser beam 10 is used here to locally melt the element that is to be connected.

(25) This produces a melt zone, denoted with reference sign 410, with liquid copper material and a melt zone, designated with reference sign 420, with solid copper material.

(26) It is clearly apparent from the comparison of FIGS. 1 and 2 that in heat conduction welding, the melt zones 41 and 42 are significantly smaller than the melt zones 410 and 420 during deep welding.

(27) FIG. 2 furthermore also clearly shows that a distinctive vapor capillary 50 is formed, which can lead to process instabilities.

(28) The vapor capillary 50 here comprises a first region 51 arranged partially inside the element that is to be connected and comprising a channel including plasma.

(29) The vapor capillary 50 furthermore comprises a second region 52, which can be referred to as laser-induced plasma.

(30) The vapor capillary 50 furthermore also comprises a third region 53, in which metal vapor can stream from the vapor capillary 5.

(31) In such a method, a significantly increased welding depth as compared to heat conduction welding is formed.

(32) It is assumed here in relation to many materials, although for example not for copper, that the process instabilities due to the vapor capillary 50 are controllable and the large welding depth produced is thus a predominant advantage.

(33) It should be noted once again at this point that in the heat conduction welding shown in FIG. 1, which can be performed using a method according to the invention, no vapor capillary is produced, and as a result such process instabilities can be reduced.

(34) As is furthermore apparent from a comparison of FIGS. 1 and 2, the welding depth in heat conduction welding is also significantly reduced.

(35) Due to the lower welding depth in heat conduction welding, which depth can consequently also be made to be more constant, it is also possible for the formation of spatters to be reduced, which was already identified as a problem in the introductory part.

(36) Overall, it is possible with heat conduction welding to thus form a reliable connection between a bond element made from copper and a contact element made from copper.