Welding method for ultrathin metal electrode connecting wire

Abstract

The invention provides a welding method of an ultrathin metal electrode connecting wire, which comprises the following steps of: tabletting the front end of a cylindrical lead wire to form a sheet structure of which the area is greater than the spot area of welding laser; the sheet-shaped structure is attached to the bonding pad of the ultrathin metal electrode and is placed and pressed tightly; and regulating and controlling the power of the welding laser and a focusing light spot, and welding the sheet-shaped structure on the bonding pad. According to the method, welding between the ultrathin electrode and the electrode lead can be achieved, and the welding efficiency is high.

Description

Technical Field

[0001] The present disclosure relates to the technical field of neural electrodes, and in particular to a welding method for ultra-thin metal electrode wires. Background Art

[0002] Platinum-iridium alloy is the mainstream conductive material for electrodes implanted in the body, with good biocompatibility and tolerance to electrical stimulation. With the development of implantable electrode technology and the demand for neural electrical signal recording, especially the pursuit of high-throughput and high-spatial-resolution implantable neural electrodes, in order to obtain more regulation or recording information, more and more electrode channels are required to be implanted in the body.

[0003] In order to reduce implant damage, increase the biocompatibility of electrodes, and extend the in vivo service life of electrodes, the size of a single electrode should be as small as possible, provided that the electrical and mechanical properties of the electrodes are guaranteed. One method of implementing such devices is to use micro-machining processes such as photolithography and etching commonly used in micro-electromechanical systems (MEMS). Another method is to use laser processing technology. At present, some international companies, such as cortex in Germany and BMseed in the United States, or research institutions, have successively developed some implantable platinum-iridium alloy electrode arrays made of platinum-iridium alloy films with a thickness of only a dozen microns. Generally, these electrodes are first processed using micro-machining processes such as laser cutting, and then the platinum-iridium alloy wire with a diameter of tens of microns is melted together with the electrode by laser welding or resistance welding. Both forms of welding do not require solder, and a firm and reliable connection is formed by melting the two parts of the welding material. As the thickness of the platinum-iridium alloy used to prepare the electrode decreases, when laser welding is used, since the platinum-iridium alloy wire is usually cylindrical, when the other ultra-thin platinum sheets that need to be welded are placed in parallel, if the welding laser spot is too large, it is very easy to burn holes instead of welding points at the welding position; if the laser spot is too small, it can only melt the welding wire, and cannot effectively melt the platinum-iridium alloy sheet, and cannot form an effective weld. Summary of the invention

[0004] In view of the above problems, the present invention provides a welding method for ultra-thin metal electrode wires to solve the above technical problems.

[0005] One aspect of the present disclosure provides a method for welding ultra-thin metal electrode connections, comprising: pressing the front end of a cylindrical lead to form a sheet structure having an area larger than the spot area of ​​a welding laser; placing and pressing the sheet structure in contact with a pad of an ultra-thin metal electrode; and regulating the power and focus spot of the welding laser to weld the sheet structure to the pad.

[0006] According to an embodiment of the present disclosure, the method of regulating the power and the focusing spot of the welding laser to weld the sheet-like structure to the pad includes: by regulating the power and the focusing spot of the welding laser, the area of ​​the sheet-like structure melted by the welding laser is controlled to be in the contact area between the sheet-like structure and the pad, thereby forming a weld between the sheet-like structure and the pad.

[0007] According to an embodiment of the present disclosure, the sheet structure is smaller in size than the pad.

[0008] According to an embodiment of the present disclosure, the diameter of the cylindrical lead is 30 microns.

[0009] According to an embodiment of the present disclosure, the thickness of the sheet structure is less than 10 micrometers.

[0010] According to an embodiment of the present disclosure, the thickness of the pad is less than 10 microns.

[0011] According to an embodiment of the present disclosure, the material of the pad is at least one of platinum, iridium or gold.

[0012] According to an embodiment of the present disclosure, the material of the cylindrical lead is the same as that of the pad.

[0013] According to an embodiment of the present disclosure, the back side of the pad is covered with insulating material.

[0014] At least one of the above technical solutions adopted in the embodiments of the present disclosure can achieve the following beneficial effects:

[0015] The welding method of the ultra-thin metal electrode connection provided by the embodiment of the present disclosure does not require auxiliary materials, can form welding spots with better strength, better flatness and smaller size, and has high welding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0017] Figure 1 The schematic diagram of welding a traditional ultra-thin metal electrode and a metal lead provided by an embodiment of the present disclosure is schematically shown.

[0018] Figure 2 A schematic diagram of welding of an ultra-thin metal electrode connection provided by an embodiment of the present disclosure is shown schematically.

[0019] Description of reference numerals:

[0020] 1-lead; 2-metal electrode; 3-soldering pad. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0022] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0023] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0024] Figure 1 The schematic diagram of welding a traditional ultra-thin metal electrode and a metal wire provided by an embodiment of the present disclosure is schematically shown.

[0025] like Figure 1 As shown, area A shows a plan view of the metal electrode 2 and the lead 1, and areas B and C show cross-sectional views of the pad 3 and the lead 1, where area B shows the shape of the lead 1 and the pad 3 before welding, and area C shows the shape of the pad 3 burned through by the laser after welding. The electrode 2 connection wire is usually a platinum-iridium wire with a diameter of about 30 microns. When it is stacked on top of a platinum sheet with a thickness of only 10 microns and welded using a pulsed laser, due to the large difference in thickness of the two materials, especially the thin thickness of the pad 3, the laser pulse melts the pad 3 to form a hole instead of fusion with the platinum-iridium wire, making it very difficult to adjust the welding parameters.

[0026] Figure 2 A schematic diagram of welding of an ultra-thin metal electrode connection provided by an embodiment of the present disclosure is shown schematically.

[0027] Figure 2 The embodiment of the present disclosure schematically shows a method for welding a connection line of an ultra-thin metal electrode 2. Specifically, the method includes S1 to S3.

[0028] S1, the front end of the cylindrical lead 1 is pressed into a sheet to form a sheet structure whose area is larger than the spot area of ​​the welding laser. Furthermore, the size of the sheet structure is smaller than the pad 3.

[0029] S2, placing the sheet structure on the pad 3 of the ultra-thin metal electrode 2 and pressing it tightly.

[0030] S3, adjusting the power and focus spot of the welding laser to weld the sheet structure onto the welding pad 3.

[0031] Specifically, by adjusting the power and focus spot of the welding laser, the area where the sheet structure is melted by the welding laser is controlled to be within the contact area between the sheet structure and the pad 3, thereby forming a weld between the sheet structure and the pad 3.

[0032] Optionally, the material of the pad 3 is at least one of platinum, iridium or gold. The material of the cylindrical lead 1 is the same as that of the pad 3, and the two have the same melting point for easy welding.

[0033] In this embodiment, the diameter of the cylindrical lead 1 is 30 micrometers, the thickness of the sheet structure is less than 10 micrometers, and the thickness of the pad 3 is less than 10 micrometers.

[0034] In this embodiment, the ultra-thin metal electrode 2 is an ultra-thin platinum-iridium electrode. The electrode and mechanical connection between the ultra-thin platinum-iridium electrode and the lead wire made of the same platinum-iridium material need to be welded by laser welding or resistance welding, which does not require auxiliary materials (such as brazing). Compared with resistance welding, laser welding can form welds with better strength, better flatness and smaller size. In addition, laser welding has the advantages of simple fixtures and higher welding efficiency.

[0035] In this example, the back side of the pad 3 is covered with insulating material, so resistance welding cannot be used and only laser welding can be used.

[0036] like Figure 2 As shown, area A shows a planar schematic diagram of the metal electrode 2 and the lead 1, and the front end of the lead 1 is pressed into a sheet structure. Areas B and C show cross-sectional views of the pad 3 and the lead 1, wherein area B shows the shape of the lead 1 and the pad 3 before welding, and area C shows the shape of the sheet structure welded to the pad 3 after welding. The front end of the platinum-iridium alloy wire is squeezed into a sheet structure with a thickness similar to that of the electrode sheet, a width the same as that of the electrode pad 3, or larger than the laser spot. When laser welding is implemented, the laser pulse welding area is changed from the two high and low areas that are not in the same plane composed of the original cylindrical-plane two parts to a flat area. It is only necessary to adjust the focal spot of the laser pulse to a suitable size (much smaller than the size of the electrode pad 3), and then adjust the power of a single pulse. A smaller pulse power can melt the upper conductor sheet layer to form an observable scar; a large power will ablate through two layers of metal including the conductor and the electrode pad 3. The experimenter only needs to adjust the power between these two parameters to select the appropriate welding power. The entire layer of metal in the central area irradiated by the light spot melts and tends to adhere to the surrounding unmelted areas due to surface tension, thereby forming ablation holes on the pad 3.

[0037] The welding method of the ultra-thin metal electrode connection provided by the embodiment of the present disclosure does not require auxiliary materials, can form welding spots with better strength, better flatness and smaller size, and has high welding efficiency.

[0038] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0039] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A welding method for ultra-thin metal electrode wires, characterized in that: include: The front end of the cylindrical lead is pressed into a sheet to form a sheet structure having an area larger than the spot area of ​​the welding laser; Placing and pressing the sheet structure against the pad of the ultra-thin metal electrode; The power and focus spot of the welding laser are adjusted to weld the sheet structure onto the welding pad.

2. The method according to claim 1, characterized in that The step of regulating the power and the focus spot of the welding laser to weld the sheet structure to the welding pad comprises: By adjusting the power and focus spot of the welding laser, the area of ​​the sheet structure melted by the welding laser is controlled to be in the contact area between the sheet structure and the pad, thereby forming a weld between the sheet structure and the pad.

3. The method according to claim 1, characterized in that The sheet structure has a size smaller than the pad.

4. The method according to claim 1, characterized in that: The diameter of the cylindrical lead is 30 microns.

5. The method according to claim 1, characterized in that The thickness of the sheet-like structure is less than 10 micrometers.

6. The method according to claim 1, characterized in that The thickness of the pad is less than 10 microns.

7. The method according to claim 1, characterized in that The material of the pad is at least one of platinum, iridium or gold.

8. The method according to claim 7, characterized in that The material of the cylindrical lead is the same as that of the pad.

9. The method according to claim 1, characterized in that: The back side of the pad is covered with insulating material.

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