Method and apparatus for machining blank, and wire bonding capillary

Abstract

To provide a method for machining a blank.SOLUTION: A method for machining a blank comprises the steps of: providing a blank made of a sintered ceramic material; and laser machining the blank with a laser beam (22) oriented to impinge tangentially on a surface of the blank, while continuously rotating the blank (1) around an axis of rotation, corresponding to a longitudinal axis of the blank (1), thereby machining at least two surface sections of the blank. Therein: the at least two surface sections are rotationally symmetric with regard to the longitudinal axis (19); the at least two surface sections are separated by a boundary curve, where a curve on the surface crossing the boundary curve has a stepwise change in curvature, and a smooth change in a direction of a surface normal; or in particular the boundary curve lies in a plane that is normal to the longitudinal axis (19).SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a wire bonding capillary, and more particularly to a method and apparatus for machining a blank, and to a wire bonding capillary as recited in the preamble of the corresponding independent claim.

Background Art

[0002] Wire bonding capillaries (hereinafter simply referred to as capillaries), and their use in the wire bonding process are described, for example, in US Patent No. 6,311,890 B1. It is further known to manufacture capillaries from sintered ceramic materials and create microstructures on a part of the forward working surface. Such microstructures are shown in Chinese Patent No. 108389806, Chinese Patent No. 109860067, Chinese Patent No. 110842339, Chinese Patent No. 113764295, and Chinese Patent No. 113927187, and can be manufactured by laser ablation or sublimation. The basic shape of the capillary, especially its tip, is formed by grinding or polishing.

Summary of the Invention

Problems to be Solved by the Invention

[0003] It is an object of the present invention to create a method and apparatus for machining a blank of the type mentioned at the beginning, in particular for creating a wire bonding capillary, which enables a machining process that is faster than existing methods and apparatuses. A further object is to provide a wire bonding capillary manufactured in this way.

Means for Solving the Problems

[0004] These objects are achieved by a method and apparatus for machining a blank, and by a wire bonding capillary as recited in the corresponding independent claim.

[0005] A method for machining a blank includes the following: ·Providing a blank made of a sintered ceramic material; ·Laser machining the blank using a laser beam oriented to impinge tangentially on the surface of the blank, ·While rotating the blank about a rotation axis, where the rotation axis coincides with or is parallel to the longitudinal axis of the blank, ·Thereby machining at least two surface sections of the blank, ○ The at least two surface sections are rotationally symmetric with respect to the longitudinal axis, ○ The at least two surface sections are separated by a boundary curve, and a curve on the surface intersecting the boundary curve has a stepwise change in curvature and a smooth change in the direction of the surface normal, ○ In particular, the boundary curve lies in a plane perpendicular to the longitudinal axis.

[0006] In an embodiment, the blank rotates continuously. A laser beam impinging tangentially on the surface of the blank means that at the focus or waist or in the vicinity thereof of the laser beam, a part of the laser beam does not impinge on the blank and a complementary part of the laser beam impinges on the blank. Therefore, only a part of the energy of this beam hits the material of the blank.

[0007] Generally, when laser machining a sintered ceramic material, the laser beam is oriented substantially perpendicular to the surface to be machined, i.e., substantially parallel to the surface normal of the surface. As a result, the particles of the sintered structure absorb the total energy of the laser pulse and evaporate or sublime as a whole. Thereby, the overall structure of the material surface becomes relatively rough, i.e., this roughness is determined by the particle size of the sintered material. When the laser beam is oriented tangentially to the surface, the total energy of the pulse is not absorbed by specific particles and the particles only evaporate or sublime partially. As a result, when viewed over a plurality of particles, the surface of the material has a finer structure than when the particles evaporate or sublime as a whole.

[0008] When specifying the angle of the laser beam with respect to the surface, it is understood that the direction of the surface is not necessarily the direction of the local surface patch that is machined and modified by the laser beam, but rather the average and overall direction of the surface. This may also be referred to as the average plane or reference plane in the cross-section of the surface of the blank being machined.

[0009] For example, when microstructures are machined on the working surface or face surface of a capillary, the angle of the laser beam is taken with respect to the surface defined by the face angle FA. Similarly, when machining the outer diameter surface, the angle of the laser beam is taken with respect to the surface defined by the outer diameter OR. Typically, the surface of the blank before machining is similar (in a geometric sense) or identical to the average plane or reference plane.

[0010] In particular, when the direction is said to be tangential to the outer circumference or perimeter of the blank or capillary, this means that it is essentially tangential to a circle in a plane perpendicular to the longitudinal axis of the blank or capillary, and the radius of the circle is the average radius of the outer surface of the blank or capillary.

[0011] As is generally known, the second-order behavior of a space curve is described by its tangent, curvature, and normal vectors.

[0012] In an embodiment, the method includes machining at least one surface of the blank using a laser beam oriented to completely impinge on the surface at an angle greater than 20 degrees, or greater than 40 degrees, or greater than 60 degrees, or greater than 80 degrees with respect to the surface. Thus, it is possible for the entire laser beam to strike the surface.

[0013] In particular, at least one surface is a surface that has already been machined using a laser beam oriented tangentially to the surface.

[0014] This makes it possible to machine the surface to form microstructures on the surface. While doing so, it is not necessary to continuously rotate the blank. In the case of a blank for a capillary, this may also be the case for small structures on the face surface and / or the inner chamfer surface. Such small structures may form, for example, in the form of bonding wires joined to the capillary. For certain surface sections, it is possible to machine the reference shape tangentially while rotating the blank and machine the microstructures with a fully incident laser beam.

[0015] In an embodiment, when machining small structures on the surface, the angle of the laser beam with respect to the surface can be adjusted by tilting the longitudinal axis of the blank with respect to the direction of the laser beam. Typically, the laser beam is tilted such that the surface to be machined is at least approximately perpendicular to the laser beam. The relative tilt can be achieved by moving the blank and / or the laser beam, or both, with respect to the environment.

[0016] For machining microstructures on the face surface, the longitudinal axis may be at least substantially parallel to the laser beam. When the blank is machined into a capillary, the longitudinal axis may be at an angle that is at least approximately equal to the face angle FA. In either case, by controlling the direction of the laser beam, the laser beam can be displaced in its direction and in a direction orthogonal to the blank. Such displacement is also possible by moving the blank in these directions, but the speed decreases.

[0017] In an embodiment, the blank has a rotationally symmetric shape that has rotational symmetry, particularly circular symmetry or n-fold rotational symmetry where n is an integer greater than 1, with respect to rotation about the longitudinal axis of the blank.

[0018] This enables such blanks to be machined by rotating them about the longitudinal axis. In an embodiment, the blank is held in a working fixture that rotates relative to the laser beam.

[0019] In an embodiment, the method includes machining two or three or four or all surfaces of the blank without interruption, in particular one or more of the following apply: · Continuously operating the laser to generate a series of laser pulses during machining of adjacent surfaces; · Holding the blank at the same position of the end effector of the working fixture.

[0020] This enables a continuous machining operation, that is, a smooth transition of the machining operation from one surface section to an adjacent surface section to machine one or more surface sections.

[0021] In an embodiment, the continuous operation of the laser includes pulsed operation of the laser and / or changing the parameters of the laser operation during operation.

[0022] In an embodiment, holding the blank at the same position of the end effector of the working fixture includes moving the end effector together with the blank without changing the relative position between the end effector and the blank. The end effector, and thus the blank, is movable in at least two degrees of freedom. Such two degrees of freedom may be, for example, rotation about the longitudinal axis of the blank and inclination of the longitudinal axis of the blank.

[0023] In an embodiment, the blank is for a wire bonding capillary. Typically, it may have an outer diameter of less than 3 millimeters, in particular less than 2 millimeters.

[0024] This enables the capillary to be machined, in particular by machining the outer surface sections in the region of the tip of the capillary in a single process step. Such portions include one or more of a tapered portion, an outer diameter surface, a face surface, and an inner chamfer surface. The tapered portion may have a bottleneck shape or a stepped shape and may have corresponding sub-sections of the surface corresponding to the tapered portion. The single process step may include holding and rotating the capillary blank and moving the laser beam and the rotating capillary blank relative to each other, thereby machining these regions successively in one continuous process.

[0025] The at least two surface sections separated by the boundary curve may be the tapered portion and the outer diameter surface of the capillary. Thus, a smooth transition is created at the boundary curve between the two. In particular, when viewed in a cross-section with the capillary axis, the surface of the capillary at the tapered portion extends tangentially to the outer diameter surface.

[0026] In an embodiment, the method includes continuously rotating blank 1 at a rotational speed around the axis of rotation that is greater than 200 RPM or greater than 800 RPM or greater than 1,000 RPM or greater than 4,000 RPM or greater than 10,000 RPM.

[0027] This rotational speed enables the entire blank or capillary to be machined in a relatively short time.

[0028] In an embodiment, the length of the laser pulse is between 100 and 1,000 femtoseconds, particularly between 200 and 800 femtoseconds, more specifically between 200 and 500 femtoseconds.

[0029] In an embodiment, the repetition frequency of the laser pulse is from 10 kHz to 800 MHz, particularly from 10 kHz to 10 MHz, more specifically 50 kHz to 1 MHz.

[0030] This makes it possible to maintain an output level that enables rapid and accurate machining of the material.

[0031] Short laser pulses enable a high pulse frequency. The energy of each pulse, and thus the average laser output, can be made relatively high. As a result, even if part of the laser is directed tangentially to the workpiece and does not hit the workpiece, the energy of the part hitting the particles of the sintered workpiece is sufficient to evaporate or sublime some of the particles.

[0032] The high pulse frequency enables spatial overlap of consecutive pulses on the material being machined when it rotates under the laser beam. This spatial overlap results in a reduction in the roughness of the machined surface and an improvement in accuracy.

[0033] In an embodiment, the wavelength of the laser pulse is between 500 and 550 nanometers, particularly between 515 and 532 nanometers.

[0034] In contrast to a laser source with a longer wavelength, in a corresponding laser source operating in the green part of the spectrum (about 495 - 570 nanometers, more narrowly 500 - 550 nanometers), the absorption near the surface of the material being machined is better. This leads to a more reliable ablation or sublimation process. This reduces cracking and chipping of the material being machined. Also, the beam waist can be made smaller, and thus smaller shaped objects can be machined.

[0035] In an embodiment, the fluence of a series of laser pulses is between 5 and 20 J / cm 2 and particularly the wavelength of the pulse is between 515 and 532 nanometers.

[0036] This makes it possible to overcome the ablation threshold, particularly for the materials envisioned in this context.

[0037] In an embodiment, the main material of the blank is sintered alumina, or sintered zirconia, or a sintered mixture of alumina and zirconia. In particular, at least one of the following applies: · The density of the sintered material (which may be one of the above materials or another sintered material) is at least 96%, · The hardness of this material is at least 1200 HV1 (HV represents Vickers hardness or Vickers pyramid number).

[0038] These material properties are particularly suitable for capillaries. In an embodiment, the particle size of the blank material is less than 3 micrometers, particularly less than 2 micrometers.

[0039] In an embodiment, the method includes machining a capillary blank as follows: · Orienting the longitudinal axis of the blank so as to be substantially perpendicular to the direction of the laser beam, and machining the outer periphery of the blank using a laser beam that impinges tangentially on the outer periphery of the blank, ○ In particular, the outer periphery includes one or more of a tapered portion, an outer diameter surface, and a face surface; · Orienting the longitudinal axis of the blank so as to be substantially parallel to the direction of the laser beam, and machining one or more surfaces of the blank using a laser beam that impinges completely on these surfaces, ○ In particular, these surfaces are one or more of a face surface and an inner chamfered surface.

[0040] This enables machining the entire outer surface of the capillary in a single continuous process.

[0041] The longitudinal axis of the blank being substantially perpendicular to the direction of the laser beam means that the angle between them is greater than 45 degrees, specifically greater than 60 degrees, and more specifically greater than 80 degrees.

[0042] The longitudinal axis of the blank being substantially parallel to the direction of the laser beam means that the angle between the two is less than 45 degrees, specifically less than 30 degrees, and more specifically less than 10 degrees.

[0043] The direction of the laser beam and the axis of the capillary form two skew lines as long as they do not intersect. The angle between the two skew lines is the angle between one of them and a straight line drawn parallel to the other through a point on the first line.

[0044] In an embodiment, the method further includes machining a blank for a capillary by orienting the longitudinal axis of the blank parallel to the direction of the laser beam, and machining at least one of the inner chamfer surface of the blank and the hole surface such that the laser beam impinges tangentially on the hole surface.

[0045] This enables machining of important portions of the inner surface of the capillary in an extension of the same continuous process.

[0046] In an embodiment, the method includes machining a blank for a capillary by orienting the longitudinal axis of the blank such that the blank intersects the laser beam at least approximately and the laser beam is tangential to the outer diameter surface or the face surface.

[0047] This enables machining of these surfaces from a different angle. In an embodiment, the method includes the following to align the outer surface of the blank with an existing hole or wire supply opening present in the blank: · Measuring the deviation of the hole with respect to the axis of rotation; · Compensating for the deviation by deflecting the laser beam according to the angular position of the blank when machining the blank.

[0048] The deviation compensation is performed, in particular, in a direction perpendicular to the axis of rotation and in a direction perpendicular to the direction of the laser beam.

[0049] This makes it possible to machine the outer surface of the blank to be concentric with the hole. The center of the hole is generally on the longitudinal axis of the blank or the capillary. The machined outer surface usually comprises one or more of a tapered portion, an outer diameter surface, a face surface, and an inner chamfered surface.

[0050] The apparatus for machining the blank comprises the following: · A laser source for generating a laser beam for machining the blank, the laser source being configured to deflect the laser beam in a direction orthogonal to the direction of the laser beam; · A fixture for holding and rotating the blank 1 around the axis of rotation, the axis of rotation coinciding with or being parallel to the longitudinal axis 19 of the blank 1; · The laser source and the fixture are configured to be movable relative to each other to set the angle between the axis of rotation and the laser beam, ○ In particular, between a relative position where they are substantially perpendicular and a relative position where they are substantially parallel.

[0051] This makes it possible to machine all relevant surfaces of the capillary, including the micro surface structure, with a single apparatus.

[0052] The wire bonding capillary is manufactured by the method described herein. This may have a smooth transition at the boundary curve between two sections, where, when viewed in a cross-section including the longitudinal axis of the capillary, the surface of the capillary extends tangentially from one of the two sections to the other. One or more of the following may apply. That is, the tapered portion and the outer diameter surface extend tangentially to each other, the outer diameter surface and the face surface extend tangentially to each other, and the face surface and the inner chamfered surface extend tangentially to each other.

[0053] In an embodiment, for at least one surface section, the overall shape of the surface is generated by laser machining with a beam that impinges in a tangential direction, and the microstructures on the surface are generated by a beam that impinges completely.

[0054] Further embodiments are apparent from the dependent claims. The features of the method claims can be combined with the features of the apparatus claims and vice versa.

[0055] The subject matter of the present invention will be described in more detail in the following text with reference to the exemplary embodiments shown in the accompanying drawings.

Brief Description of the Drawings

[0056]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Modes for Carrying Out the Invention

[0057] As a general rule, the same or functionally identical parts are marked with the same reference signs in the figures.

[0058] Figures 1 and 2 schematically show the generally used parameters defining the shape of the capillary 1, namely the face angle FA, the outer diameter OR, the hole diameter H, the chamfer diameter CD, the tip diameter T, the inner chamfer angle ICA, the outer diameter OD, the taper angle (or cone angle) CA, and the tool length TL, as seen in a cross-sectional view of the capillary 1.

[0059] In the region of the tip of the capillary 1, the orientation or curvature of the surface section is defined by the corresponding parameters. The surface section shall be labeled as follows, following the surface from the outside to the inside.

[0060] · An outer diameter surface characterized by the outer diameter OD. · A tapered portion 11 characterized by the main taper angle MTA (alternatively, the terms chamfer surface or cone angle CA can be used). If the tapered portion 11 has a bottleneck shape with sub-sections of different angles (Figure 3), this can be characterized by two corresponding taper angles, for example, the main taper angle MTA and the bottleneck angle BNA, and the bottleneck height BNH. If the tapered portion 11 has a stepped shape with corresponding sub-sections (Figure 4), it can be characterized by additional parameters.

[0061] · An outer diameter surface 12 characterized by the outer diameter OR. · A face surface 13 characterized by the face angle FA. The face surface 13 may also be called the working surface.

[0062] · An inner chamfer surface 14 characterized by the inner chamfer angle ICA. As shown in Figure 2, there may be two or more inner chamfer surfaces adjacent to each other and having different characteristic angles.

[0063] · A hole surface 15 characterized by the hole diameter H. The hole provided with the hole surface 15 may also be called the wire supply opening.

[0064] Since the blank becomes a capillary by the machining process described in this specification, the terms "blank" and "capillary" are somewhat interchangeable. Thus, the blank can be considered an incomplete form of the capillary. Also, referring to the capillary axis 19, this is the same as or at least parallel to the axis or longitudinal axis of the blank 1. Thus, if the laser beam 22 has a specific angle with respect to the capillary axis 19, it has the same angle with respect to the longitudinal axis of the blank 1, and if the plane is perpendicular to the capillary axis 19, it is also perpendicular to the longitudinal axis of the blank 1.

[0065] Generally, the compartments and sub-compartments are rotationally symmetric, and thus the blank 1 can be machined by rotating it around its longitudinal axis, and the laser beam impinges on the blank 1 tangentially.

[0066] In practice, the longitudinal axis of the blank 1 may not coincide with the central axis of the hole present in the blank 1. That is, the hole and the blank 1 are not concentric. In such a case, it is possible to machine the blank so that the outer shape of the resulting capillary is concentric with the hole. As a result, the capillary axis 19 of the final blank 1 does not coincide with the longitudinal axis of the original blank. This can be achieved by mechanically compensating for the eccentricity of the outer surface of the blank with respect to the hole. This can also be achieved by measuring the eccentricity of the hole with respect to the blank 1 and controlling the laser beam so as to compensate for the eccentricity of the hole by deflecting the laser beam 22 in synchronization with the rotation of the blank 1 when machining the blank 1, and machining the surface of the capillary to be concentric with the hole.

[0067] The following examples show a capillary axis 19 that coincides with the longitudinal axis and the rotational axis of the blank 1, and the method of applying the examples when the axes do not coincide will be apparent to those skilled in the art.

[0068] Figs. 5 to 6 are a schematic perspective view of a laser beam colliding in a tangential direction and a view seen in the direction of the capillary axis 19. The laser beam 22 is generated, for example, by a laser source 21 including a laser light generator, a light guiding means, a collimating optical system and a focusing optical system, and a deflecting means for slightly deflecting the laser beam 22 in a direction orthogonal to the direction of the beam. The laser beam 22 is schematically indicated by an arrow, and it is understood that the beam waist is a focused beam located at or near the point where it collides with the blank 1 being machined by laser ablation or sublimation by the laser beam 22. The direction of rotation of the blank 1 is indicated by an arrow. The direction of rotation is usually such that the surface moves relative to the direction of the laser beam 22 that collides with it.

[0069] Fig. 7 shows what happens when the laser beam completely collides with the surface of a sintered material composed of particles 4 sintered together. The surface is substantially horizontal in the drawing, and only a very small cross-section is schematically shown. If the energy of the laser beam 22 hitting the particles 4 of the material exceeds a certain limit within a specific time interval, the energy absorbed by the particles 4 evaporates or sublimates them as a whole before the energy dissipates to other particles 3. This is shown by the removed particles 41 surrounded by a dotted line. The overall result of machining the surface in this way is that the surface roughness corresponds to the size of the particles 4 of the material. Therefore, by hitting the surface, and thus the particles 4, tangentially, only a part of the particles 4 is removed, and the resulting overall surface has a finer and rougher structure.

[0070] Figure 8 shows a laser beam 22 that impinges on the surface in a tangential direction. The laser beam 22 does not completely hit the surface, and a part of it can pass completely through the surface. Each individual particle 4 does not receive the total energy of the beam and thus does not completely evaporate or sublime. Rather, the energy is sufficient to evaporate or sublime only a part of one or more particles that are hit tangentially by the beam. This is shown by the removed part 42 of the particles that is enclosed by the dotted line. The overall result of machining the surface in this way is that, as shown in Figure 7, the surface roughness is smaller than when the laser beam hits completely.

[0071] Figure 9 shows a laser beam that impinges on the tapered portion 11 of the blank for the capillary 1 in a tangential direction. Its longitudinal axis 19 is at an angle f with respect to the direction of the laser beam 22. This angle f is generally a right angle. Preferably, this is greater than 45 degrees, particularly greater than 60 degrees, and more specifically greater than 80 degrees. The laser beam 22 oriented in this way can be used to machine the outer periphery of the blank 1 in a state where the laser beam 22 impinges tangentially. The surface machined in this way can be the tapered portion 11, the outer diameter surface 12, and the face surface 13.

[0072] Here, and in other examples, the direction of the laser beam 22 and the axis of the capillary 19 can form two skew lines. The angle f between these two skew lines is the angle between one of them and a straight line drawn parallel to the other through a point on the first line.

[0073] FIG. 10 shows a laser beam that impinges completely on the face surface 13 of the blank for the capillary 1. Its longitudinal axis 19 is at an angle f with respect to the direction of the laser beam 22. This angle f is generally small, i.e., the two directions are generally parallel. Preferably, the angle f is less than 45 degrees, particularly less than 30 degrees, and more specifically less than 10 degrees. The laser beam 22 oriented in this way can be used to machine one or more surfaces of the blank using a laser beam that impinges completely on these surfaces. The surfaces machined in this way can be the face surface 13 and the inner chamfer surface 14. It is also possible to machine the hole surface 15, particularly such that the laser beam 22 is parallel to the axis of the hole surface 15 and the capillary axis 19. The laser beam 22 can also be oriented with respect to (or vice versa) the capillary axis 19 such that the laser beam 22 impinges tangentially on the face surface 13, offset from or intersecting the capillary axis 19 as shown in FIG. 9.

[0074] Figure 11 shows an apparatus for machining a blank. In addition to the laser source 21, the laser beam 22 and the blank or capillary 1 already described, a fixture 3 for holding the blank or capillary 1 and a articulation link 31 between the laser source 21 and the fixture 3 are shown very schematically. The articulation link 31 is a mechanical link mechanism between the two. This enables the two to move relative to each other, and in principle it does not matter how the two move relative to the environment. Typically, this relative movement comprises rotating the fixture 3 about an axis of rotation and setting the angle between this axis of rotation and the direction of the laser beam 22. Typically, this axis of rotation coincides with the longitudinal axis of the blank 1 held by the articulation link 31. The angle of rotation is shown as r in the figure and the direction of the axis of rotation as e. In this example, e is the elevation angle on the X-Y plane of a reference Euclidean coordinate system. The laser source 21 is oriented such that the laser beam 22 is essentially in the Z direction of this coordinate system, perpendicular to the X-Y plane. The laser source 21 enables the laser beam 22 to be deflected slightly in the X and Y directions, thereby being able to cover a working area including at least the width and length of the capillary 1 that needs to be machined. This may be a few millimeters, for example up to 5 millimeters or 10 millimeters, measured from the laser source 21 where the capillary 1 is located. Using this arrangement, by setting the elevation angle e and adjusting the angle f between the capillary axis 19 and the direction of the laser beam 22 (while maintaining the machining area of the capillary 1 in the working area of the laser source 21), the capillary 1 can be machined as described above. This can be achieved by rotating the fixture 3 while keeping the laser source 21 fixed relative to the environment. Alternatively, the axis of rotation of the fixture 3 may remain fixed relative to the environment and the laser source 21 may rotate around the working area (in this case, the XYZ coordinate system rotates with the laser source 21). In an embodiment, the axis of rotation of the fixture 3 may also rotate around the azimuth angle a around the Z axis, especially while maintaining the tip of the capillary 1 in the working area.

[0075] In an embodiment not shown, a measuring device such as a camera is arranged to take an image along the rotation axis of the fixture 3 and the blank 1. At least before machining the blank, the camera determines the position of the capillary 1 and / or the central hole of the capillary with respect to the rotation axis, i.e., the eccentricity of the hole and the fixture 3. Instead of a camera, a one-dimensional sensor may be used to measure the eccentricity while rotating the blank around the rotation axis of the fixture. When machining the blank, the laser beam 22 may be continuously deflected to compensate for the eccentricity according to the angular position of the fixture 3 as it rotates.

[0076] Although the present invention has been described in this embodiment, it is clearly understood that the present invention is not limited thereto and can be embodied and implemented in various other ways within the scope of the claims.

Claims

1. A method for machining a blank, comprising the following steps: - providing a blank made of a sintered ceramic material; - laser machining the blank using a laser beam (22) oriented to impinge tangentially on the surface of the blank; - rotating the blank (1) about a rotation axis, wherein the rotation axis coincides with or is parallel to the longitudinal axis (19) of the blank (1); - thereby machining at least two surface sections of the blank; ○ the at least two surface sections are rotationally symmetric with respect to the longitudinal axis; ○ the at least two surface sections are separated by a boundary curve, and a curve on the surface intersecting the boundary curve has a stepwise change in curvature and a smooth change in the direction of the surface normal; ○ in particular, the boundary curve lies in a plane perpendicular to the longitudinal axis; A method comprising the above steps.

2. Machining at least one surface of the blank (1) using the laser beam (22) oriented to impinge completely on the surface at an angle greater than 20 degrees, or greater than 40 degrees, or greater than 60 degrees, or greater than 80 degrees with respect to the surface, in particular; In particular, the at least one surface is a surface that has already been machined using a laser beam oriented tangentially to the surface. The method according to claim 1. [[ID= ​ ​ ​ ​ ​ ​ ​ ​ The method according to any one of the preceding claims, wherein the length of the laser pulse is between 100 and 1000 femtoseconds, particularly between 200 and 800 femtoseconds, more specifically between 200 and 500 femtoseconds.

7. The method according to any one of the preceding claims, wherein the repetition frequency of the laser pulse is from 10 kHz to 800 MHz, particularly from 10 kHz to 10 MHz, more specifically from 50 kHz to 1 MHz.

8. The method according to any one of the preceding claims, wherein the wavelength of the laser pulse is between 500 and 550 nanometers, particularly between 515 and 532 nanometers.

9. The fluence of the series of the laser pulses is between 5 and 20 J / cm ２ The method according to any one of the preceding claims, wherein the fluence is between 5 and 20 J / cm, and in particular the wavelength of the pulses is between 515 and 532 nanometers.

10. The main material of the blank 1 is sintered alumina, or sintered zirconia, or a sintered mixture of alumina and zirconia, In particular, the method according to any one of the preceding claims, wherein at least one of the following applies, ・ The density of the sintered material is at least 96%, ・ The hardness of the material is at least 1200 HV1, The method comprising.

11. The method according to any one of the preceding claims, wherein the particle size of the material of the blank is less than 3 micrometers, particularly less than (2) micrometers.

12. The method according to any one of the preceding claims according to claim 4, comprising machining the blank (1) as follows, ・ Orienting the longitudinal axis of the blank so as to be substantially perpendicular to the direction of the laser beam (22), and machining the outer periphery of the blank (1) using the laser beam (22) that impinges tangentially on the outer periphery of the blank, ○ In particular, the outer periphery includes one or more of a tapered portion (11), an outer diameter surface (12), and a face surface (13), ・ Orienting the longitudinal axis of the blank so as to be substantially parallel to the direction of the laser beam (22), and machining one or more surfaces of the blank (1) using the laser beam (22) that completely impinges on these surfaces, ○ In particular, these surfaces are one or more of a face surface (13) and an inner chamfer surface (14), The method comprising.

13. Orienting the longitudinal axis of the blank parallel to the direction of the laser beam (22), and machining at least one of the inner chamfered surface (14) of the blank (1) and the hole surface (15) by the laser beam (22) impinging tangentially on the hole surface (15). The method according to claim 12.

14. A method according to any one of the preceding claims according to claim 4, comprising the following to align the outer surface of the blank (1) with an existing hole or wire supply opening present in the blank (1). - Measuring the deviation of the hole with respect to the axis of rotation. - Compensating for the deviation of the hole, particularly in a direction perpendicular to the axis of rotation and in a direction perpendicular to the direction of the laser beam (22), by deflecting the laser beam (22) according to the angular position of the blank (1) when machining the blank (1). A method comprising.

15. An apparatus for machining a blank, configured to perform the method according to any one of the preceding claims, comprising: - A laser source (21) for generating a laser beam (22) for machining the blank (1), the laser source (21) being configured to deflect the laser beam (22) in a direction orthogonal to the direction of the laser beam (22). - A fixture (3) for holding and rotating the blank (1) around an axis of rotation, the axis of rotation being coincident with or parallel to the longitudinal axis (19) of the blank (1). - The laser source (21) and the fixture (3) are arranged to be movable relative to each other to set the angle between the longitudinal axis and the laser beam (22). ○ In particular, an apparatus that is between a relative position where they are substantially perpendicular and a relative position where they are substantially parallel.

16. A wire bonding capillary manufactured by the method according to any one of the preceding claims 1 to 14, wherein, when viewed in a cross-section including the axis of rotation, the surface of the capillary particularly has a smooth transition at the boundary curve between two sections, where the surface of the capillary extends tangentially from one of the two sections to the other. In particular, one or more of the following apply, and the tapered portion (11) and the outer diameter surface (12) extend in a tangential direction with respect to each other, the outer diameter surface (12) and the face surface (13) extend in a tangential direction with respect to each other, and the face surface (13) and the inner chamfered surface (14) extend in a tangential direction with respect to each other: a wire bonding capillary.

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