Method and apparatus for processing a blank and wire bonding chip

Abstract

A method of processing a body comprising the steps of: providing a body made of a sintered ceramic material; the invention relates to a method for producing a green body (1), comprising the steps of:-laser-processing the green body using a laser beam (22) oriented to be applied tangentially to the surface of the green body,-continuously rotating the green body (1) simultaneously about an axis of rotation corresponding to the longitudinal axis of the green body (1),-thereby processing at least two surface portions of the green body, o the at least two surface portions are rotationally symmetrical with respect to the longitudinal axis (19), and o at least two surface portions are separated by a boundary curve, the curvature of the curve across the surface crossing the boundary curve having a step-like change and having a smooth transition in the direction of the surface normal, o in particular wherein the boundary curve lies in a plane perpendicular to the longitudinal axis (19).

Description

Field of the Invention

[0001] The present invention relates to a wire bonding capillary, and more particularly to a method and apparatus for processing a blank and a wire bonding capillary as described in the preamble of the corresponding independent claims. Background Art

[0002] Wire bonding capillaries (hereinafter simply referred to as capillaries) and their use in wire bonding processes are described, for example, in US6311890 B1. In addition, it is also known to manufacture capillaries from sintered ceramic materials and to form small-scale structures on a part of the front working surface. Such small-scale structures are shown in CN108389806, CN109860067, CN110842339, CN113764295 and CN113927187 and can be manufactured by laser ablation or sublimation. The basic shape of the capillary, especially its tip, is formed by grinding and polishing. Summary of the Invention

[0003] It is an object of the present invention to create a method and apparatus for processing blanks of the initially described type, in particular for manufacturing wire bonding capillaries, which allow a faster processing process than existing methods and apparatuses. Another object is to provide a wire bonding capillary manufactured in this way.

[0004] These objects are achieved by a method and apparatus for processing a blank and a wire bonding capillary according to the corresponding independent claims.

[0005] The method for processing a blank includes the following steps:

[0006] · Providing a blank made of sintered ceramic material;

[0007] · Laser processing the blank using a laser beam directed tangentially to the surface of the blank,

[0008] · Simultaneously rotating the blank about a rotation axis that is aligned with or parallel to the longitudinal axis of the blank,

[0009] · Thereby processing at least two surface portions of the blank,

[0010] o The at least two surface portions are rotationally symmetric about the longitudinal axis, and

[0011] o The at least two surface portions are delimited by a boundary curve, where the curvature of a curve crossing the boundary curve on the surface has a step change and has a smooth transition in the direction of the surface normal,

[0012] o In particular, the boundary curve lies in a plane perpendicular to the longitudinal axis.

[0013] In an embodiment, the green body rotates continuously. The tangential application of the laser beam to the surface of the green body means that at the focus or beam waist or in the vicinity thereof of the laser beam, a part of the laser beam is not applied to the green body, while the remaining part of the laser beam is applied to the green body. Therefore, only a part of the beam energy is applied to the material of the green body.

[0014] Generally, when laser processing and sintering ceramic materials, the laser beam is usually perpendicular to the surface being processed, that is, usually parallel to the surface normal of the surface. This causes the grains of the sintered structure to absorb all the energy of the laser pulse and evaporate or sublime as a whole. This correspondingly results in a relatively rough overall structure of the material surface: the roughness is determined by the grain size of the sintered material. If the laser beam is oriented tangentially to the surface, not all the energy of the pulse is absorbed by a specific grain, and the grain will only partially evaporate or sublime. Therefore, when observing multiple grains, the surface structure of the material is finer than when the entire grains evaporate or sublime.

[0015] It can be understood that when specifying the angle of the laser beam relative to the surface, the direction of the surface is not necessarily the direction of the local surface patch that is processed and changed by the laser beam, but the average global direction of the surface. This can also be referred to as the average surface or reference surface in the part of the surface of the green body being processed.

[0016] For example, when processing small-scale structures on the working surface or end face of a splitting tool, the angle of the laser beam is selected relative to the surface defined by the end face angle FA. Similarly, when processing the outer radius surface, the angle of the laser beam is selected relative to the surface defined by the outer radius OR. Generally, the surface of the green body before processing is similar or even identical to the average surface or reference surface (in a geometric sense).

[0017] Specifically, when it is said that a certain direction is tangent to the outer circumference or circumference of the green body or splitting tool, this means that the direction is substantially tangent to a circle located in a plane perpendicular to the longitudinal axis of the green body or splitting tool, and the radius of the circle is the average radius of the outer surface of the green body or splitting tool.

[0018] As is well known, the second-order variation of a space curve is described by its tangent, curvature, and normal vector.

[0019] In an embodiment, the method includes processing at least one surface of the green body, wherein the laser beam is oriented to be fully applied to the surface, particularly at an angle relative to the surface greater than 20° or greater than 40° or greater than 60° or greater than 80°. Therefore, the entire laser beam can be applied to the surface.

[0020] In particular, at least one surface is a surface that has been previously processed using a laser beam oriented tangentially to the surface.

[0021] In this way, the surface can be machined to form small-scale structures in the surface. While doing so, the blank does not need to be rotated continuously. For the blank of the wedge, this can be the case for small-scale structures in the end faces and / or inner chamfered surfaces. Such small-scale structures can, for example, form the shape of a bond wire to which the wedge is bonded. For specific surface sections, a reference shape can be machined tangentially while the blank is rotated and small-scale structures are machined by the fully applied laser beam.

[0022] In an embodiment, when machining small structures on a surface, the angle of the laser beam relative to the surface can be adjusted by tilting the longitudinal axis of the blank relative to the direction of the laser beam. Typically, the tilting is such that the machined surface is at least approximately perpendicular to the laser beam. The relative tilting can be achieved by moving the blank or the laser beam or both relative to the environment.

[0023] For machining small structures on the surface, the longitudinal axis can be at least approximately parallel to the laser beam. For a blank to be machined into a wedge, the longitudinal axis can be tilted by an angle at least approximately equal to the face angle FA. In both cases, a displacement of the laser beam in a direction orthogonal to its direction and in a direction relative to the blank can be achieved by controlling the direction of the laser beam. Such displacement can also be achieved by moving the blank in these directions, but at a slower speed.

[0024] In an embodiment, the blank has a rotationally symmetrical shape with respect to a rotation about a longitudinal axis of the blank, in particular has a circular symmetry or has an n-fold rotational symmetry, wherein n is an integer greater than one.

[0025] This makes it possible to process such a blank by rotation about the longitudinal axis.In an embodiment, the blank is held in an actuatable fixture, wherein the blank is rotated relative to the laser beam.

[0026] In an embodiment, the method comprises machining two, three, four or all surfaces of the blank without interruption, in particular one or more of the following:

[0027] Continuously operate the laser to produce a series of laser pulses between processing of adjacent surfaces;

[0028] • Keep the blank in the same position in the end effector of the actuating fixture.

[0029] This makes it possible to machine one or more surface portions in a continuous machining operation, ie the machining operation transitions smoothly from one surface portion to an adjacent surface portion.

[0030] In an embodiment, continuous operation of the laser includes pulsed operation of the laser and / or changes in operating parameters of the laser during operation.

[0031] In an embodiment, keeping the blank in the same position in the end effector of the actuating fixture comprises moving the end effector together with the blank, the relative position of the end effector and the blank remaining unchanged. The end effector and the blank can move with at least two degrees of freedom. Two such degrees of freedom can be: rotation around the longitudinal axis of the blank, and tilting of the longitudinal axis of the blank.

[0032] In an embodiment, the green body is used for a wire bonding wedge. Typically, its outer radius may be less than three millimeters, in particular less than two millimeters.

[0033] This makes it possible to machine the cleaver, in particular by machining the outer surface portions in the region of the cleaver tip in a single process step. These portions include one or more conical surfaces, outer radius surfaces, end surfaces and inner chamfered surfaces. The conical surface can have a bottleneck shape or a stepped shape, as well as a corresponding sub-portion of the surface corresponding to the conical surface. A single process step can include clamping and rotating the cleaver blank, and moving the laser beam and the rotating cleaver blank relative to each other, so that these regions are processed successively in one continuous process.

[0034] The at least two surface portions separated by the boundary curve may be the cone surface and the outer radius surface of the splitting cutter. Therefore, a smooth transition is generated at the boundary curve between the two. Specifically, from the cross section including the axis of the splitting cutter, the surface at the cone of the splitting cutter extends tangent to the outer radius surface.

[0035] In an embodiment, the method comprises continuously rotating the blank 1 about the rotation axis at a rotation speed of greater than 200 revolutions per minute (RPM), or greater than 800 RPM, or greater than 1000 RPM, or greater than 4000 RPM, or greater than 10000 RPM.

[0036] This rotation speed makes it possible to machine the entire blank or splitter in a relatively short time.

[0037] In an embodiment, the length of the laser pulse is between 100 and 1000 femtoseconds, in particular between 200 and 800 femtoseconds, more in particular between 200 and 500 femtoseconds.

[0038] In an embodiment, the repetition frequency of the laser pulses is between 10 kHz and 800 MHz, in particular between 10 kHz and 10 MHz, more in particular between 50 kHz and 1 MHz.

[0039] This makes it possible to maintain a certain power level to process materials quickly and precisely.

[0040] Short laser pulses allow for a higher pulse frequency. The energy per pulse, and thus the average laser power, can be relatively high. Thus, even if part of the laser light (if it is directed tangentially toward the workpiece) does not hit the workpiece, the energy of the part that hits the grains of the sintered workpiece is sufficient to evaporate or sublimate part of the grain.

[0041] The high pulse frequency allows continuous pulses to overlap spatially on the material being processed as it rotates under the laser beam. The spatial overlap reduces the roughness of the processed surface and improves the accuracy.

[0042] In an embodiment, the wavelength of the laser pulses is between 500 and 550 nanometers, in particular between 515 and 532 nanometers.

[0043] The corresponding laser sources operate in the green part of the spectrum (between approximately 495-570 nanometers, and more narrowly between 500 and 550 nanometers), which results in a higher absorption rate near the surface of the processed material than laser sources with longer wavelengths. This leads to a more reliable ablation or sublimation process. This in turn reduces cracking and fragmentation of the processed material. In addition, the beam waist can be made smaller, and therefore smaller features can be processed.

[0044] In an embodiment, the optical flux of the laser pulse sequence is between 5 and 20 J / cm 2 between 515 and 532 nanometers.

[0045] This allows overcoming the ablation threshold, particularly for the materials envisaged herein.

[0046] In the embodiment, the main material of the green body is sintered alumina, or sintered zirconia, or a sintered mixture of alumina and zirconia. Specifically, at least one of the following conditions exists:

[0047] the density of the sintered material (whether one of the above materials or another sintered material) is at least 96%,

[0048] The hardness of the material is at least 1200 HV1 (HV stands for Vickers hardness or Vickers pyramid number).

[0049] These material properties are particularly suitable for riving knives.

[0050] In an embodiment, the grain size of the material of the green body is less than 3 microns, in particular less than 2 microns.

[0051] In an embodiment, the method comprises the step of machining the riving tool blank by the following steps:

[0052] orienting the longitudinal axis of the blank approximately at right angles to the direction of the laser beam and machining the periphery of the blank, wherein the laser beam is applied tangentially to the periphery of the blank,

[0053] o In particular, wherein the outer periphery includes one or more conical surfaces, outer radius surfaces and end surfaces;

[0054] orienting the longitudinal axis of the blank approximately parallel to the direction of the laser beam and processing one or more faces of the blank, wherein the laser beam is fully applied to these faces,

[0055] o In particular wherein the faces are one or more of end faces and inner chamfered surfaces.

[0056] This makes it possible to machine the entire outer surface of the riving knife in a single continuous process.

[0057] The longitudinal axis of the blank is generally at right angles to the direction of the laser beam, meaning that the angle therebetween is greater than 45°, in particular greater than 60°, more in particular greater than 80°.

[0058] The longitudinal axis of the blank being substantially parallel to the direction of the laser beam means that the angle therebetween is smaller than 45°, in particular smaller than 30°, more in particular smaller than 10°.

[0059] The direction of the laser beam and the axis of the wedge, unless they intersect, form two oblique lines. The angle between the two oblique lines is the angle between one of the oblique lines and a line drawn through a point on the first line and parallel to the other oblique line.

[0060] In an embodiment, the method comprises the further steps of machining the blank for the wedge 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 and the hole surface of the blank with a laser beam applied tangentially to the hole surface.

[0061] This makes it possible to machine critical sections of the cutter's inner surface in an extended phase of the same continuous process.

[0062] In an embodiment, the method comprises the step of machining a blank for a riving cutter by positioning the longitudinal axis of the blank so that it at least approximately intersects the laser beam and such that the laser beam is tangential to the surface of the outer radius surface or the end face.

[0063] This makes it possible to machine these surfaces from another angle.

[0064] In an embodiment, in order to align the outer surface of the blank with an existing hole or wire feeding hole in the blank, the method comprises the following steps:

[0065] ·Measure the eccentricity of the hole relative to the axis of rotation;

[0066] When processing the blank, deviations are compensated by deflecting the laser beam according to the angular position of the blank.

[0067] The compensating deflection is carried out in particular in a direction perpendicular to the axis of rotation and perpendicular to the direction of the laser beam.

[0068] In this way, the outer surface of the blank can be processed to be coaxial with the hole. The center of the hole is usually located on the longitudinal axis of the blank or the splitter. The outer surface processed here usually includes one or more of a conical surface, an outer radius surface, an end face and an inner chamfer surface.

[0069] Equipment for processing blanks, including

[0070] a laser source for generating a laser beam for processing the blank, the laser source being configured to deflect the laser beam in a direction orthogonal to the direction of the laser beam;

[0071] A clamp for holding the blank 1 and rotating it about an axis of rotation which is aligned with or parallel to the longitudinal axis 19 of the blank 1;

[0072] the laser source and the fixture are arranged to be movable relative to each other to set an angle between the longitudinal axis and the laser beam,

[0073] o In particular, an angle is set between their substantially perpendicular relative position and their substantially parallel relative position.

[0074] This makes it possible to machine all relevant surfaces of the riving tool, including small surface structures, in a single machine.

[0075] A wire bonding knife is manufactured by the method described herein. It may include a smooth transition at a boundary curve between two parts, where the surface of the knife extends tangentially from one of the two parts to the other part, viewed along a cross section including the axis of rotation. One or more of the following may exist: the conical surface and the outer radius surface extend tangentially to each other, the outer radius surface and the end surface extend tangentially to each other, and the end surface and the inner chamfer surface extend tangentially to each other.

[0076] In an embodiment, for at least one surface portion, the overall shape of the surface is created by laser machining with a beam applied tangentially, while the small-scale structures on the surface are created by fully impinging the beam.

[0077] Further embodiments are evident from the dependent claims. Features of method claims may be combined with features of device claims and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The subject matter of the invention will be explained in more detail below with reference to exemplary embodiments shown in the accompanying drawings, which schematically illustrate:

[0079] Figure 1 : Cross-sectional views of bonding tools with different tip types;

[0080] Figure 2 : Parameters of the riving cutter tip area;

[0081] Figure 3 : Bottle neck cleaver tip:

[0082] Figure 4 : Stepped chopper tip;

[0083] Figures 5-6 : The laser beam applied tangentially to;

[0084] Figure 7 : Laser beam that fully impinges on the surface;

[0085] Figure 8 : laser beam applied tangentially to the surface;

[0086] Figure 9 : The laser beam is applied tangentially to the cone surface of the wedge;

[0087] Figure 10 : The laser beam is applied completely to the surface of the cleaver;

[0088] Figure 11 : Equipment used for processing blanks.

[0089] In principle, identical or functionally identical components are provided with the same reference symbols in the figures. DETAILED DESCRIPTION

[0090] Figure 1 and Figure 2 The common parameters of the geometry of the riving tool 1 are schematically shown. From the cross-sectional view of the riving tool 1, it can be seen: the end angle FA, the outer radius OR, the hole diameter H, the chamfer diameter CD, the tip diameter T, the inner chamfer ICA, the outer diameter OD, the taper angle (or cone angle) CA and the tool length TL.

[0091] In the area of the tip of the riving knife 1, the orientation or curvature of the surface portion is defined by the corresponding parameters. The surface portion should be marked as follows from the outside to the inside:

[0092] • Outside diameter surface, characterized by the outside diameter OD.

[0093] • The conical surface 11 is characterized by a main cone angle MTA (alternatively, the term chamfered surface and cone angle CA may be used). If the conical surface 11 has a bottleneck shape, the angles of its sub-sections are different ( Figure 3 ), then it can be characterized by two corresponding cone angles, such as the main cone angle MTA and the bottleneck angle BNA and the bottleneck height BNH. If the cone surface 11 has a stepped shape with corresponding sub-sections ( Figure 4 ), then it can be characterized by other parameters.

[0094] • An outer radius surface 12, characterized by an outer radius OR.

[0095] • End surface 13, characterized by end angle FA. End surface 13 may also be referred to as working surface.

[0096] • An internal chamfered surface 14, characterized by an internal chamfer ICA. Figure 2 As shown, there may be multiple inner chamfered surfaces adjacent to each other and having different characteristic angles.

[0097] • A hole surface 15, which is characterized by a hole diameter H. A hole having a hole surface 15 may also be referred to as a wire feeding hole.

[0098] The terms "blank" and "wedge" are somewhat interchangeable, since the machining process described herein transforms the blank into a wedge. Thus, the blank can be considered as an unfinished form of a wedge. Furthermore, if reference is made to the wedge axis 19, this is identical to, or at least parallel to, the axis or longitudinal axis of the blank 1. Thus, if the laser beam 22 is at an angle to the wedge axis 19, it is at the same angle to the longitudinal axis of the blank 1, and if the plane is perpendicular to the wedge axis 19, it is also perpendicular to the longitudinal axis of the blank 1.

[0099] Typically, the portions and sub-portions are rotationally symmetrical and can therefore be processed by rotating the blank 1 about its longitudinal axis and applying the laser beam tangentially to the blank 1 .

[0100] In practice, it is possible that the longitudinal axis of the blank 1 is not aligned with the central axis of the hole present in the blank 1. That is, the hole and the blank 1 are not coaxial. In this case, the blank can be processed so that the outer shape of the produced splitting knife is coaxial with the hole. As a result, the splitting knife axis 19 of the final blank 1 is not aligned 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 relative to the hole. It can also be achieved by measuring the eccentricity of the hole relative to the blank 1, and when processing the blank 1, by synchronously deflecting the laser beam 22 with the rotation of the blank 1 to control the laser beam 22 to compensate for the eccentricity of the hole, so that the surface of the splitting knife is processed to be coaxial with the hole.

[0101] The following examples show that the riving knife axis 19 is aligned with the longitudinal axis and the rotation axis of the blank 1, and it will be apparent to a person skilled in the art how to adjust for the case where the axes are not aligned.

[0102] Figures 5-6A tangentially applied laser beam is shown in a schematic perspective view and a view along the direction of the capillary axis 19. The laser beam 22 is generated by a laser source 21, which includes, for example, a laser generator, a light guiding device, collimating and focusing optics, and a deflection device for small-scale deflection of the laser beam 22 in a direction orthogonal to the laser beam direction. The laser beam 22 is schematically represented by an arrow, and it should be understood that it is a focused beam, where the beam waist is located at or near the site applied to the blank 1. The blank 1 is processed using the laser beam by laser ablation or sublimation. The direction of rotation of the blank 1 is represented by an arrow. The direction of rotation is generally such that the surface moves against the direction in which the laser beam 22 is applied or irradiated to it.

[0103] Figure 7 Shows what happens when the laser beam is fully irradiated onto the surface of a sintered material composed of mutually sintered grains 4. This surface is generally horizontal in the figure, and only a very small part is schematically shown. If the energy of the laser beam 22 irradiated onto the material grains 4 within a certain time interval exceeds a certain limit, the energy absorbed by the grains 4 will cause them to evaporate or sublime as a whole, and then the energy will only dissipate to other grains 3. This is represented by the removed grains 41 outlined with a dashed line. The overall result of processing the surface in this way is that the roughness of the surface corresponds to the size of the material grains 4. Therefore, by tangentially applying to the surface and thus also irradiating the grains 4, only part of the grains 4 are removed, and the resulting overall surface has a finer and less rough structure.

[0104] Figure 8 Shows the laser beam 22 tangentially applied to the surface. The laser beam 22 is not fully applied to the surface, and part of the laser beam may pass completely through the surface. A single grain 4 does not receive all the energy of the beam, so it does not evaporate or sublime completely. Instead, the energy is only sufficient to evaporate or sublime a part of one or more grains that are tangentially irradiated by the laser beam. This is represented by the removed part 42 of the grains outlined with a dashed line. The overall result of processing the surface in this way is that the roughness of the surface is less than the case where the laser beam is fully irradiated (as Figure 7 shown).

[0105] Figure 9 Shows the laser beam tangentially applied to the conical surface 11 of the blank of the capillary 1. Its longitudinal axis 19 forms an angle f with the direction of the laser beam 22. This angle f is generally a right angle. Preferably, this angle is greater than 45°, especially greater than 60°, more especially greater than 80°. The laser beam 22 oriented in this way can be used to process the outer periphery of the blank 1 in the case of tangential application of the laser beam 22. The surface processed in this way can be the conical surface 11, the outer radius surface 12, and the end surface 13.

[0106] Here and in other embodiments, 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 formed between one of the skew lines and a straight line passing through a point on the first line and parallel to the other skew line.

[0107] Figure 10 It is shown that the laser beam completely irradiates the surface 13 of the blank of the capillary 1. Its longitudinal axis 19 forms an angle f with the direction of the laser beam 22. This angle f is usually very small, that is to say, the two directions are substantially parallel. Preferably, the angle f is less than 45°, particularly less than 30°, and more particularly less than 10°. The laser beam 22 oriented in this way can be used to machine one or more surfaces of the blank, where the laser beam is fully applied to these surfaces. The surfaces machined in this way can be the end face 13 and the inner chamfer surface 14. The hole surface 15 can also be machined, particularly with the laser beam 22 parallel to the axis of the hole surface 15 and the capillary axis 19. The laser beam 22 can also be oriented relative to the capillary axis 19 (or vice versa) such that the laser beam 22 is applied tangentially to the end face 13, or is offset from the capillary axis 19, as Figure 9 shown, or intersects the capillary axis 19.

[0108] Figure 11Shows a device for processing a blank. In addition to the laser source 21, the laser beam 22, and the blank or the splitting tool 1 that have been described, it very schematically shows a fixture 3 for fixing the blank or the splitting tool 1, and a pivot link 31 between the laser source 21 and the fixture 3. The pivot link 31 is a linkage mechanism between the two. It allows the two to move relative to each other, and in principle, how the two move relative to the environment is not important. Usually, the relative movement includes rotating the fixture 3 around a rotation axis and setting the angle between this rotation axis and the direction of the laser beam 22. Usually, this rotation axis is aligned with the longitudinal axis of the blank 1 held in the pivot link 31. The rotation angle is denoted as r in the figure, and the direction of the rotation axis is denoted as e. In the example, e is the elevation angle on the X - Y plane of the reference Euclidean coordinate system. The orientation of the laser source 21 is such that the laser beam 22 is substantially in the Z direction perpendicular to the X - Y plane of this coordinate system. The laser source 21 allows the laser beam 22 to be deflected by small angles in the X and Y directions so that it can cover a working area that at least includes the width and length of the splitting tool 1 that needs to be processed. This can be a few millimeters, for example, not exceeding 5 or 10 millimeters, which can be measured at a certain distance from the laser source 21 where the splitting tool 1 is arranged. With this arrangement, the angle f between the splitting tool axis 19 and the direction of the laser beam 22 can be adjusted by setting the elevation angle e (while keeping the processing area of the splitting tool 1 within the working area of the laser source 21), and the splitting tool 1 can be processed in the above - mentioned manner. This can be achieved by keeping the laser source 21 fixed relative to the environment and rotating the fixture 3. Alternatively, the rotation axis of the fixture 3 can be kept fixed relative to the environment, while the laser source 21 can rotate around the working area (in this case, the XYZ coordinate system rotates with the laser source 21). In an embodiment, the rotation axis of the fixture 3 can also rotate azimuthally by an angle a around the Z axis, especially to keep the tip of the splitting tool 1 within the working area.

[0109] In an embodiment not shown, a measuring device such as a camera is arranged to acquire images along the rotation axis of the fixture 3 and the blank 1. At least before processing the blank, the camera determines the position of the central hole in the splitting tool relative to the splitting tool 1 and / or the rotation axis, that is, the eccentricity of the hole and the fixture 3. A one - dimensional sensor can be used instead of the camera to measure the eccentricity while rotating the blank around the rotation axis of the fixture. When processing the blank, the laser beam 22 can be continuously deflected according to the angular position during the rotation of the fixture 3 to compensate for the eccentricity.

[0110] Although the present invention has been described in the foregoing embodiments, it is clearly understood that the present invention is not limited thereto, but can be implemented and practiced in various other ways within the scope of the claims.

Claims

1. A method for processing a blank, comprising the following steps: · Providing a blank made of sintered ceramic material; · Using a laser beam (22) to perform laser processing on the blank, the laser beam (22) being oriented tangentially to the surface of the blank; · Simultaneously rotating the blank (1) about a rotation axis, the rotation axis being aligned or parallel to the longitudinal axis (19) of the blank (1); · Thereby processing at least two surface portions of the blank; o The at least two surface portions are rotationally symmetric about the longitudinal axis, and o The at least two surface portions are separated by a boundary curve, wherein the curvature of the curve crossing the boundary curve on the surface has a step change and has a smooth transition in the direction of the surface normal, and o In particular, the boundary curve lies in a plane perpendicular to the longitudinal axis.

2. The method according to claim 1, comprising using a laser beam (22) to process at least one surface of the blank (1), wherein the laser beam (22) is oriented to be fully applied to the surface, in particular at an angle greater than 20° or greater than 40° or greater than 60° or greater than 80° relative to the surface, and In particular, the at least one surface is a surface previously processed using a laser beam oriented tangentially to the surface.

3. The method according to claim 1 or 2, comprising continuously processing two, three, four or all surfaces of the blank, in particular one or more of the following cases: · Operating the laser continuously to generate a sequence of laser pulses between adjacent surface processes; · Holding the blank (1) in the same position of the end effector of the drive fixture.

4. The method according to any one of the preceding claims, wherein the blank is a blank for a wire bonding wedge (1), in particular having an outer radius of less than three millimeters, in particular less than two millimeters.

5. The method according to any one of the preceding claims, comprising continuously rotating the blank (1) about the longitudinal axis at a rotational speed greater than 200 revolutions per minute or greater than 800 revolutions per minute or greater than 1000 revolutions per minute or greater than 4000 revolutions per minute or greater than 10000 revolutions per minute.

6. The method according to any one of the preceding claims, wherein the length of the laser pulse is between 100 and 1000 femtoseconds, in particular between 200 and 800 femtoseconds, more particularly 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 between 10 kHz and 800 MHz, in particular between 10 kHz and 10 MHz, more particularly between 50 kHz and 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, in particular between 515 and 532 nanometers.

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

10. The method according to any one of the preceding claims, wherein, The material of the blank (1) is sintered alumina, sintered zirconia or a sintered mixture of alumina and zirconia, In particular, at least one of the following conditions is satisfied: · The density of the sintered material is at least 96%, · The hardness of the material is at least 1200 HV1.

11. A method according to any one of the preceding claims, wherein the grain size of the material of the green body is less than three microns, in particular less than 2 microns.

12. The method according to any of the preceding claims when dependent on claim 4, comprising the step of machining the blank (1) by: orienting the longitudinal axis of the blank approximately at right angles to the direction of the laser beam (22) and machining the periphery of the blank (1), wherein the laser beam (22) is applied tangentially to the periphery of the blank, o In particular, the outer periphery includes one or more conical surfaces (11), an outer radius surface (12) and an end surface (13); orienting the longitudinal axis of the blank so as to be substantially parallel to the direction of the laser beam (22) and processing one or more faces of the blank (1), wherein the laser beam (22) is applied completely to these faces, o In particular wherein the faces are one or more of the end faces (13) and the inner chamfered surfaces (14).

13. The method according to claim 12, comprising the steps of orienting the longitudinal axis of the blank parallel to the direction of the laser beam (22), and machining at least one of the inner chamfer surface (14) and the hole surface (15) of the blank (1) using the laser beam (22) applied tangentially to the hole surface (15).

14. A method according to any preceding claim when dependent on claim 4, comprising, in order to align the outer surface of the blank (1) with an existing hole or wire feed hole in the blank (1), by the following steps: Measuring the offset of the hole relative to the axis of rotation; During the processing of the blank (1), the offset of the hole is compensated by deflecting the laser beam (22), in particular in a direction perpendicular to the axis of rotation and perpendicular to the laser beam (22), depending on the angular position of the blank (1).

15. Apparatus for processing a blank, configured to carry out the method as claimed in any one of the preceding claims, comprising: A laser source (21) for generating a laser beam (22) for processing the blank (1), wherein the laser source (21) is configured to deflect the laser beam (22) in a direction orthogonal to the direction of the laser beam (22); A clamp (3) for holding the blank (1) and rotating it about an axis of rotation which is aligned 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 in order to set an angle between the longitudinal axis and the laser beam (22), o In particular, an angle is set between their substantially perpendicular relative position and their substantially parallel relative position.

16. A wire bonding knife produced by the method according to any one of the preceding claims 1 to 14, which has a smooth transition, in particular at the boundary curve between two parts, where the surface of the knife, viewed along a section including the axis of rotation, extends tangentially from one of the two parts to the other part, And in particular, one or more of the following situations exist: the conical surface (11) and the outer radius surface (12) extend tangentially to each other, the outer radius surface (12) and the end surface (13) extend tangentially to each other, and the end surface (13) and the inner chamfer surface (14) extend tangentially to each other.

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