阅读说明：本技术 焊线工具及其形成方法 (Wire bonding tool and method of forming the same ) 是由 J·W·布伦纳 R·希拉克 T·J·沃克 于 2020-07-27 设计创作，主要内容包括：提供一种焊线工具,所述焊线工具包括配置成接收线的本体部分。本体部分包括具有作业面的末端部分。作业面限定有多个凹部,所述多个凹部成多组凹部布置,每组凹部成圆形图案布置,所述多组凹部相对于彼此同心地布置。(A wire bonding tool is provided that includes a body portion configured to receive a wire. The body portion includes a tip portion having a working face. The working face defines a plurality of recesses arranged in sets of recesses, each set of recesses arranged in a circular pattern, the sets of recesses arranged concentrically with respect to one another.)

1. A wire bonding tool, characterized in that the wire bonding tool comprises:

configured to receive a body portion of the wire,

the body portion includes a distal end portion,

the end portion includes a working surface that,

the working face defines a plurality of recesses arranged in sets of recesses, each set of recesses arranged in a circular pattern, the sets of recesses arranged concentrically with respect to one another.

2. The wire bonding tool of claim 1, wherein the plurality of distinct recesses comprises a plurality of holes.

3. The wire bonding tool of claim 2, wherein the plurality of holes have a substantially common diameter.

4. The wire bonding tool of claim 2 wherein each of the plurality of holes has a substantially common depth.

5. The wire bonding tool of claim 2, wherein a depth of each of the plurality of holes varies along a length or width of the hole.

6. The wire bonding tool of claim 2, wherein at least one of the plurality of holes has a depth that is different from a depth of another of the plurality of holes.

7. The wire bonding tool of claim 1, wherein each set of recesses is disposed concentrically with an inner bore in the wire face configured to receive a wire.

8. The wire bonding tool of claim 1, wherein the working face comprises 4 sets of recesses concentrically arranged relative to each other and relative to an inner bore of the working face.

9. The wire bonding tool of claim 1, wherein the plurality of sets of recesses are concentrically arranged relative to each other to cover substantially an entire working face of the tip portion.

10. A method of forming a wire bonding tool, the method comprising the steps of:

(a) providing a wire bonding tool having a body portion configured to receive a wire, the body portion including a tip portion, the tip portion having a working surface; and

(b) forming a plurality of distinct recesses in the working face, the plurality of recesses arranged in sets of recesses, each set of recesses arranged in a circular pattern, the sets of recesses arranged concentrically with respect to one another.

11. The method of claim 10, wherein step (b) comprises forming each set of recesses to be arranged concentrically with an inner bore in the wire face configured to receive a wire.

12. The method of claim 10, wherein step (b) comprises forming the plurality of recesses using (i) a laser machining process, (ii) a fluid-jet milling process, (iii) a direct molding process, (iv) a mechanical grinding process, or (v) an electro-discharge machining process.

13. The method of claim 10, wherein step (b) comprises forming the plurality of recesses using a laser machining process.

14. The method of claim 10, wherein the plurality of recesses comprises a plurality of holes.

15. The method of claim 11, wherein the plurality of holes have a substantially common diameter.

16. The method of claim 11, wherein each of the plurality of holes has a substantially common depth.

17. The method of claim 11, wherein the depth of each of the plurality of holes varies along the length or width of the hole.

18. The method of claim 11, wherein at least one of the plurality of holes has a depth that is different from a depth of another of the plurality of holes.

19. The method of claim 10, wherein the work surface includes 4 sets of recesses concentrically arranged relative to each other and relative to an inner bore of the work surface.

20. The method of claim 10, wherein the plurality of sets of recesses are concentrically arranged relative to each other to cover substantially an entire working face of the tip portion.

Technical Field

The present invention relates to bonding tools used in wire bonding systems, and more particularly, to an improved tip portion of a bonding tool.

Background

In the processing and packaging of semiconductor devices, wire bonding continues to be the primary method of providing electrical interconnection between two locations within a package, such as between a die pad of a semiconductor die and a lead of a leadframe. To form a wire loop (wire loop) that provides the interconnection, a bonding tool (e.g., a capillary tool) is used. Typical capillary tools are made of non-conductive (e.g., ceramic) materials such as alumina, zirconia toughened alumina, and ruby, among others. The bonding tool may also be made of other types of materials, such as, for example, electrically conductive materials as well as electrically dissipative materials.

An exemplary conventional wire bonding sequence using ball bonding includes: (1) forming a ball bond at a first location (e.g., a die pad of a semiconductor die) with a bonding tool; (2) a wire extending a length in a desired shape between a first location and a second location (such as a second location such as a lead of a leadframe); (3) stitch welding the wire to a second location to form a second weld; and (4) cutting the wire.

Each of the following U.S. patent documents relates to the field of bonding tools for wire bonding machines: U.S. patent application publication No. 2008/0314963 entitled "binding Tool With Improved Finish"; U.S. Pat. No. 7,500,591 entitled "Low-Profile Capillary For Wire binding"; U.S. Pat. No. 7,500,590 entitled "Multi-Part Capillary"; U.S. Pat. No. 7,004,369 entitled "Capillary with connected Inner Chamfer"; U.S. Pat. No. 6,729,527 entitled "binding Tool With Polymer Coating"; U.S. Pat. No. 6,715,658 entitled "Ultra Fine Pitch Capillary"; U.S. Pat. No. 6,523,733 entitled "Controlled attention Capillary"; U.S. Pat. No. 6,073,827 entitled "Wire binding Capillary With A cosmetic Surface"; U.S. patent No. 5,931,368 entitled "Long Life binding Tool"; U.S. Pat. No. 5,871,141 entitled "Fine Pitch binding Tool for Constrained binding"; and U.S. patent No. 5,421,503 entitled "Fine Pitch mining binding Tool," and the contents of each are incorporated by reference.

Conventional ball bonding tools typically have polished or smooth ceramic surfaces. The polished or smooth surface includes a working face at the end portion of the bonding tool. In certain applications, an alternative finish may be provided at the tip surface of the bonding tool. See, for example, U.S. patent application publication No. 2008/0314963 entitled "binding Tool With Improved Finish".

Also, wire bonding tools having other rough surfaces at the working face of the capillary are known, such as a scraped surface, a thermally etched surface, a laser machined surface, and the like. In the wire bonding industry, there is a continuing pressure for developments that provide improved results such as increased wire bond strength (e.g., first weld strength, second weld strength, etc.), reduced coordination rates for welding operations, reduced variability between wire loops, increased welding tool life, etc.

Specific development is required for specific applications and markets. One example application/market involves the LED (light emitting diode) market and wire bonds associated with that application/market.

Accordingly, it would be desirable to provide an improved wire bonding tool.

Disclosure of Invention

According to an exemplary embodiment of the present invention, a wire bonding tool is provided that includes a body portion configured to receive a wire. The body portion includes a tip portion having a working face. The working face defines a plurality of recesses arranged in sets of recesses, each set of recesses arranged in a circular pattern, the sets of recesses arranged concentrically with respect to one another. In certain embodiments of the invention, the plurality of sets of recesses are concentrically arranged relative to each other to cover substantially the entire working face of the tip portion.

According to another exemplary embodiment of the present invention, a method of forming a wire bonding tool is provided. The method comprises the following steps: a wire bonding tool is provided having a body portion configured to receive a wire. The body portion includes a tip portion having a working face. The method further comprises the steps of: a plurality of recesses are formed in the worksurface and arranged in sets of recesses, each set of recesses arranged in a circular pattern, the sets of recesses arranged concentrically with respect to each other. In certain embodiments of the invention, the plurality of sets of recesses are concentrically arranged relative to each other to cover substantially the entire working face of the tip portion.

The step of forming the plurality of recesses may employ techniques such as, for example: laser machining, fluid-jet milling, direct molding techniques, mechanical grinding, EDM (electrical discharge machining), or combinations thereof.

According to one aspect of the present application, there is provided a wire bonding tool comprising: a body portion configured to receive a wire, the body portion including a tip portion, the tip portion including a working surface, the working surface defining a plurality of recesses, the plurality of recesses being arranged in sets of recesses, each set of recesses being arranged in a circular pattern, the sets of recesses being concentrically arranged relative to one another.

Optionally, the plurality of distinct recesses comprises a plurality of holes.

Optionally, the plurality of holes have a substantially common diameter.

Optionally, each of the plurality of holes has a substantially common depth.

Optionally, the depth of each of the plurality of holes varies along the length or width of the hole.

Optionally, at least one of the plurality of holes has a depth different from a depth of another of the plurality of holes.

Optionally, each set of recesses is arranged concentrically with an inner bore in the wire face configured to receive a wire.

Optionally, the working face comprises 4 sets of recesses arranged concentrically with respect to each other and with respect to the inner bore of the working face.

Optionally, the sets of recesses are arranged concentrically with respect to each other to cover substantially the entire working face of the tip portion.

According to another aspect of the present application, there is provided a method of forming a wire bonding tool, the method comprising the steps of: (a) providing a wire bonding tool having a body portion configured to receive a wire, the body portion including a tip portion, the tip portion having a working surface; and (b) forming a plurality of distinct recesses in the working face, the plurality of recesses arranged in a plurality of sets of recesses, each set of recesses arranged in a circular pattern, the plurality of sets of recesses arranged concentrically with respect to one another.

Optionally, step (b) comprises forming each set of recesses to be arranged concentrically with an inner bore in the wire face configured to receive a wire.

Optionally, step (b) comprises forming the plurality of recesses using (i) a laser machining process, (ii) a fluid-jet milling process, (iii) a direct molding process, (iv) a mechanical grinding process, or (v) an electrical discharge machining process.

Optionally, step (b) comprises forming the plurality of recesses using a laser machining process.

Optionally, the plurality of recesses comprises a plurality of holes.

Optionally, the plurality of holes have a substantially common diameter.

Optionally, each of the plurality of holes has a substantially common depth.

Optionally, the depth of each of the plurality of holes varies along the length or width of the hole.

Optionally, at least one of the plurality of holes has a depth different from a depth of another of the plurality of holes.

Optionally, the working face comprises 4 sets of recesses arranged concentrically with respect to each other and with respect to the inner bore of the working face.

Optionally, the sets of recesses are arranged concentrically with respect to each other to cover substantially the entire working face of the tip portion.

Drawings

The invention is best understood from the following detailed description when read with the accompanying drawing figures. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures:

fig. 1A is a cross-sectional view of a wire bonding tool according to an exemplary embodiment of the present invention;

FIG. 1B is an enlarged view of a portion of FIG. 1A;

fig. 2A is an end view of a wire bonding tool according to an exemplary embodiment of the present invention;

fig. 2B is a perspective view of a tip portion of the wire bonding tool of fig. 2A;

fig. 3A-3B are photographs of another wire bonding tool according to an exemplary embodiment of the present invention;

fig. 4A-4B are photographs of yet another wire bonding tool according to an exemplary embodiment of the present invention; and

fig. 5-7 are side view block diagrams illustrating the depth of a recess of a wire bonding tool according to various exemplary embodiments of the present invention.

Detailed Description

According to certain exemplary embodiments of the present invention, an improved work surface for a bonding tool is provided. The improved working surface may improve the characteristics of the first weld and/or the second weld formed in connection with the wire loop. More specifically, a recess is formed in the working surface, as desired in a given application, for example to improve wire bonding.

Fig. 1A is a side cross-sectional view of a wire bonding tool 100, such as capillary 100. As understood by those skilled in the art, the wire bonding tool 100 may be formed using a cylindrical blank (e.g., a ceramic blank) that has been milled, ground, and/or polished to define other features such as a tapered portion, a working surface, an inner chamfer, an outer radius, and the like. The bonding tool 100 includes a cylindrical portion 102 and a tapered portion 104, both collectively referred to as a body portion. A weld line (not shown) may be received within the body portion passageway 102 a.

Upper terminal end 118 of cylindrical portion 102 may be configured to be engaged in a transducer (not shown) of a wire bonding machine. The lower terminal end of the body portion is a tip portion 106 (including a working face 114) and is configured for forming a wire bond at a bonding location.

FIG. 1B is a detailed view of the portion of FIG. 1A labeled "FIG. 1B". The body portion 102 includes a tapered portion 104 that terminates in a tip portion 106. The tip portion 106 defines an inner bore 108 (the end of the passage 102 a), an inner chamfer 110, an outer radius 112, and a working surface 114. The work surface 114 defines an outer region that contacts, for example, a weld line during welding.

As provided above, the bonding tool may be formed from a blank that is machined (e.g., milled, ground, polished, etc.) to include certain features, such as the working surface 114. The working face 114 is illustrated as a generally flat surface at a face angle 130 relative to a welding plane (e.g., relative to a plane generally perpendicular to the longitudinal axis 116 of the welding tool 100). However, it is understood that the Face angles may coincide With the welding plane (e.g., they are parallel), may form negative Face angles With respect to the welding plane (see, for example, PCT international publication No. WO 2009/148450a1 entitled "Bonding Tool With Improved Working Face"), or may have curved or other non-linear surfaces.

Of course, the welding tool 100 is merely exemplary of the types of welding tools that may be provided with an improved worksurface according to the present invention. Any of a variety of other types of bonding tools may also utilize the benefits of the present invention.

In accordance with the present invention, the surface of worksurface 114 defines a recess, as illustrated, for example, in FIGS. 2, 3A-3B, 4A-4B, 5,6 and 7. Such recesses may comprise, for example, a pattern/series of holes.

The recess according to the present invention may be formed as desired in a given application. For example, the recesses may be formed in a symmetrical pattern/series. In addition, the recess may be formed only on the surface/area of the working face, or the recess may extend to other areas/surfaces of the tip portion including the inner chamfer and/or outer radius.

The term "surface plane," as used herein, refers to a surface of worksurface 114, for example, from which a recess is formed (e.g., depth) below. "depth" refers to the maximum depth of the recess below the surface plane, e.g., the working surface. By "concentric" is meant having a common center and in particular having a common center around the inner bore. "circular" refers to a shape having a circumference that follows or roughly follows a circle.

Fig. 2A is an end view of wire bonding tool 200 (where wire bonding tool 200 may be shaped substantially similar to wire bonding tool 100 of fig. 1A-1B), and fig. 2B is a perspective view of a tip portion of wire bonding tool 200. Wire bonding tool 200 includes tapered portion 204 and tip portion 206, which includes working surface 214. An inside chamfer 210 leading to a channel 202a (channel 202a, also referred to as an inner bore, extends through wire bonding tool 200 and is configured to receive a wire for wire bonding) is centered in the center of working surface 214.

Working surface 214 defines a plurality of recesses 250. The plurality of recesses 250 are arranged in sets of recesses (sets 250a, 250b, 250c, and 250 d). Each set of recesses 250a, 250b, 250c, and 250d is arranged in a circular pattern. The sets of recesses 250a, 250b, 250c, and 250d are concentrically arranged relative to one another. In the exemplary embodiment shown in fig. 2A-2B, the sets of recesses 250a, 250B, 250c, and 250d are concentrically arranged relative to one another to cover substantially the entire working face 214 of tip portion 206.

In fig. 2A-2B, there are four (4) sets of recesses 250a, 250B, 250c, and 250 d. Of course, more or fewer sets of recesses may be formed in the work surface of a wire bonding tool according to the present invention.

The plurality of recesses may be holes or other recesses. The holes may have a generally common diameter (or the diameters may vary), and the holes may have a generally common depth across the area of each hole (or the depth of each hole may vary along its length or width or the entire area). Wherein at least one of the plurality of holes has a depth that is different from a depth of another of the plurality of holes. As shown in fig. 2A-2B, each set of recesses 250a, 250B, 250c, and 250d is disposed concentrically with the internal bore (i.e., the end of the passage 202A) in the working face 214.

Fig. 3A-3B are photographs illustrating that a plurality of recesses 350 (arranged in concentric sets of recesses) substantially cover the entire working surface 314 of tip portion 306 of wire bonding tool 300. In the exemplary embodiment shown in fig. 3A-3B, inner chamfer 310 of wire bonding tool 300 is smooth (contains no recesses). Fig. 4A-4B are photographs illustrating that plurality of recesses 450 (arranged in concentric sets of recesses) substantially cover the entire working face of tip portion 406 of wire bonding tool 400. In the exemplary embodiment shown in fig. 4A-4B, inner chamfer 410 of wire bonding tool 400 defines a plurality of recesses 450 a.

It is noted that for each exemplary embodiment, including any corresponding pattern/series of recesses not specifically illustrated herein, the number of recesses and/or the surface and/or area of any series of such recesses may be increased or decreased, depending on the particular embodiment and depending on the environment of the welding process with corresponding widths, lengths, and/or radii. Additionally, although the recess may extend across at least a portion of the surface and/or area of the working face, the recess may extend to (either adjacent to or spaced from) the inner chamfer and/or the outer radius.

Fig. 5 is a cross-sectional view of an exemplary recess 520 on the working face 514 of the bonding tool 500, the exemplary recess 520 having a depth d1, d2 from a surface plane 590 of the working face 514 that varies across its width "w" or length "l," where, for example, d1> d 2. Similarly, fig. 6 is a cross-sectional view of two exemplary recesses 620a, 620b on the working face 614 of the bonding tool 600, each of the two exemplary recesses 620a, 620b having a respective depth d3, d4 from the surface plane 690 of the working face 614, wherein, for example, d3> d 4. Such varying or differing depths of fig. 5-6 may be employed with each or any of the exemplary embodiments of the present invention described herein or otherwise within the scope of the present invention. Similarly, fig. 7 is a cross-sectional view of two exemplary recesses 720a, 720b on the working face 714 of the bonding tool 700, each of the two exemplary recesses 720a, 720b having a respective depth d5, d6 from the surface plane 790 of the working face 714, where, for example, d5> d 6. Such varying or differing depths (or variations such as differing widths) of fig. 5-7 may be employed with each or any of the exemplary embodiments of the present invention described herein or otherwise within the scope of the present invention.

The recesses of the working face of the bonding tool according to the present invention may have varying depths, lengths and widths depending on the application. For example, the depth of the recesses may be between 1-10 microns, while another exemplary range is between 3-10 microns. In examples where the recesses are holes, the holes may have an exemplary radius of between 1-2 microns and a depth of 3-10 microns.

The invention also includes an exemplary method of forming the recess. In certain example methods, a wire bonding tool is provided having a body portion configured to receive a wire. The body portion includes a tip portion, and the tip portion includes a working face. A plurality of recesses are formed in the work surface (e.g., by a laser machining process).

The recess may be formed by various methods (e.g., using computer control), including, for example, laser machining, fluid-jet milling, direct molding, mechanical grinding, or EDM (electrical discharge machining).

Laser machining is a process of removing a target material (e.g., a predefined volume) from a solid by irradiating the solid with laser energy to cause evaporation or sublimation of the target material, and may include etching, milling, and the like. For example, a laser machining system may include elements such as a laser, a control system, and a positioning system. Laser machining is a non-contact process and is therefore highly desirable when working on hard materials that can be replaced with a large number of tools due to wear.

Fluid-jet milling utilizes a jet of fluid (such as a water jet with a suitable abrasive filler entrained therein) directed at high pressure to a target portion of the capillary tip. Direct molding techniques can also be employed, utilizing, for example, nanoparticle ceramics with low friction binders and ultrasonic compaction in highly refined molds. Additionally, the recesses of the exemplary embodiments may also be formed by selectively adding material to the blank or to a milled or polished bonding tool. That is, for example, additional material may be added to form the recess.

Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.