Tools for wire bonding

Abstract

Wire bonding tool comprising: a body section containing a tip section; a first coating applied to the tip section; and a second coating applied to the first coating.

Description

CROSS-REFERENCE TO LINKED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 336,033, filed April 28, 2022, the contents of which are hereby incorporated by reference. AREA

[0002] The invention relates to wire bonding tools, in particular to wire bonding tools containing coatings. BACKGROUND

[0003] In the processing and packaging of semiconductor devices and other electronic assemblies, wire bonding remains the primary method for establishing an electrical connection between two locations within a package (e.g., between a die pad of a semiconductor chip and a lead frame lead). More specifically, a wire bonder (also called a wire bonding machine) is used to form wire loops between the respective locations to be electrically connected. The main methods for forming wire loops are ball bonding and wedge bonding (including ribbon bonding).

[0004] In the wire bonding industry, contamination (including wire buildup) on the tip of the wire bonding tool and surface wear of the wire bonding tool tip limit the useful life of the wire bonding tool.

[0005] U.S. Patent No. 6,729,527 (entitled “BONDING TOOL WITH POLYMER COATING”) and U.S. Patent No. 6,171,456 (entitled “METHOD FOR MAKING IMPROVED LONG LIFE BONDING TOOLS”) relate to the coating of wire bonding tools and are hereby incorporated by reference in their entirety.

[0006] It would be desirable to provide improved wire bonding tools that overcome one or more of the deficiencies of conventional wire bonding tools. SUMMARY

[0007] According to an exemplary embodiment of the invention, a wire bonding tool is provided. The wire bonding tool includes a body portion having a tip portion. The wire bonding tool further includes a first coating applied to the tip portion. The wire bonding tool further includes a second coating applied to the first coating.

[0008] According to exemplary aspects of the invention, the wire bonding tool recited in the preceding paragraph may include any one or more of the following features: the body portion comprises at least one selection of a ceramic, a metal alloy, a metal matrix composite, and a ceramic matrix composite; the first coating is resistant to at least one selection of corrosion and wear; the first coating comprises at least one selection of a metal, a metallic compound, and a ceramic; the first coating comprises at least one selection of chromium, titanium, chromium carbide, chromium nitride, and titanium nitride; the first coating has a thickness of 0.5 to 10 micrometers; the first coating has a thickness of 0.5 to 2 micrometers; the second coating is resistant to stiction and / or friction; the second coating is carbon-based;the second coating comprises at least one selection of diamond-like carbon, non-hydrogenated diamond-like carbon, tetragonal amorphous carbon, and a carbon-based coating; the second coating has a thickness of 0.1 to 10 micrometers; and the second coating has a thickness of 0.3 to 5 micrometers.; BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, in accordance with common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily enlarged or reduced for clarity. Included in the drawings are the following figures: Fig. 1A-1C are partial cross-sectional side views of various exemplary bonding tools useful in explaining the invention; Fig. 2A-2C are partial cross-sectional side views of the wire bonding tools of the Fig. 1A-1C being coated according to various exemplary embodiments of the invention; Fig. 3A-3C are partial cross-sectional side views of the wire bonding tools of the Fig. 1A-1C coated according to various exemplary embodiments of the wire invention; Fig. 4 is a detailed view of part of the Fig. 3A-3C depict wire bonding tools according to various exemplary embodiments of the invention; and Fig. 5 is a flowchart illustrating an unclaimed method for providing a wire bonding tool. DETAILED DESCRIPTION

[0010] As used herein, the term "wire bonding tool" shall refer to any number of types of wire bonding tools, such as wedge bonding tools (e.g., small wire wedges, heavy wire wedges, etc.), ball bonding tools (e.g., capillary tools), tape bonding tools, etc.

[0011] In this document, the term "coating" refers to a material applied to the surface of a wire bonding tool. Although a second coating may be "coated" over a first coating, this does not necessarily mean that the second coating is applied directly to a first coating. In other words, an intermediate coating or layer may separate the second and first coatings; thus, a second coating may be applied indirectly to a first coating. Likewise, a coating (e.g., a first coating, a second coating, etc.) may be applied indirectly to a wire bonding tool. A "first" coating is not necessarily the innermost coating or layer of a wire bonding tool; further, the "second" coating does not necessarily have to be the outermost coating.

[0012] In the drawings the Fig. 1A-1C show various tools for wire bonding. More specifically, Fig. 1A a wedge bonding tool with a “V-shaped” groove, Fig. 1B a tape bonding tool and Fig. 1C shows a small-wire wedge bonding tool. Of course, other types of wire bonding tools are also provided within the scope of the invention. Fig. Figures 1A-1C show the tip sections of various wire bonding tools. The tip sections are the part of the wire bonding tool that comes into contact with a workpiece during a wire bonding process.

[0013] With particular reference to Fig. 1A illustrates a wire bonding tool 100. The wire bonding tool 100 includes a body portion 100a with a tip portion 100b at a terminal end. The body portion 100a includes a surface 100a1. The tip portion 100b includes a portion of the surface 100a1 referred to as surface 100b1. The tip portion 100b defines a V-shaped groove configured to receive a wire during a wire bonding operation.

[0014] In relation to Fig. 1B illustrates a wire bonding tool 102 (e.g., a ribbon bonding tool). The wire bonding tool 102 includes a body portion 102a with a tip portion 102b at a terminal end. The body portion 102a includes a surface 102a1. The tip portion 102b includes a portion of the surface 102a1 referred to as surface 102b1. The tip portion 102b includes a bonding surface 102c configured to contact a wire during a wire bonding operation.

[0015] In relation to Fig. 1C illustrates a wire bonding tool 104. The wire bonding tool 104 includes a body portion 104a with a tip portion 104b at a terminal end. The body portion 104a includes a surface 104a1. The tip portion 104b includes a portion of the surface 104a1 referred to as surface 104b1. The tip portion 104b includes a bonding surface 104c configured to contact a wire during a wire bonding operation.

[0016] The wire bonding tool 100, the wire bonding tool 102, and the wire bonding tool 104 may be referred to as "uncoated." Before applying coatings to the wire bonding tools, the wire bonding tools 100, 102, and 104 may be cleaned (e.g., degreased or otherwise cleaned, depending on the type of tool and the coating to be applied). More specifically, at least the tip portion of each wire bonding tool may be cleaned (e.g., surface 100b1, surface 102b1, and bonding surface 102c). Of course, the entire surface of each wire bonding tool may also be cleaned. In addition, a surface of each of the wire bonding tools (e.g., at least at the respective tip portion) may be "activated" so that the surfaces are more receptive to a coating (see, e.g., step 506 of Fig. 5). As is known to those skilled in the art, surface activation (e.g., of a metal wedge bonding tool) changes the surface energy of the wire bonding tool, making it more likely to attract coating particles.

[0017] Regarding the Fig. 2A-2C, each of the wire bonding tools 100, 102, and 104 has received a respective first coating, so the tools are now referred to as wire bonding tools 100', 102', and 104'. The wire bonding tool 100' includes a first coating 106 applied to the tip portion 100b, the wire bonding tool 102' includes a first coating 106 applied to the tip portion 102b, and the wire bonding tool 104' includes a first coating 106 applied to the tip portion 104b. The respective first coatings may be considered an internal coating or a layer applied to the respective surface of the tip portion of the wire bonding tool. Although the first coatings 106 in the Fig. 2A-2C are applied only to the tip portion of the respective wire bonding tool, it is understood that any portion of the surface of the wire bonding tool (including the entire surface) may be coated.

[0018] In the Fig. 3A-3C, it can be seen that each of the wire bonding tools 100, 102 and 104 has a corresponding second coating (after the first coating 106 in the Fig. 2A-2C), so that the tools are now referred to as wire bonding tools 100", 102", and 104". The wire bonding tool 100" includes a second coating 108 (on top of the first coating 106) applied to the tip portion 100b, the wire bonding tool 102" includes a second coating 108 (on top of the first coating 106) applied to the tip portion 102b, and the wire bonding tool 104" includes a second coating 108 (on top of the first coating 106) applied to the tip portion 104b. The respective second coatings may be considered an outer coating or layer applied to the first (or inner) coating of the tip portion of the respective wire bonding tool. Although the Fig. 3A-3C illustrate the second coating 108 applied only to the tip portion of the respective wire bonding tool, it should be understood that any portion of the surface of the wire bonding tool (including the entire surface) may be coated.

[0019] In relation to Fig. 4, a portion of the wire bonding tool 100" (or the wire bonding tool 102" or the wire bonding tool 104") is shown to more clearly show the first coating 106 and the second coating 108. Although in Fig. 4, the first coating 106 and the second coating 108 are illustrated as having approximately the same thickness, the invention is not so limited. For example, in certain embodiments of the invention, the first coating 106 may have a thickness of 0.5 to 10 micrometers; in other embodiments of the invention, the first coating 106 may have a thickness of 0.5 to 2 micrometers. For example, in certain embodiments of the invention, the second coating 108 may have a thickness of 0.1 to 10 micrometers; in other embodiments of the invention, the second coating 108 may have a thickness of 0.3 to 5 micrometers. Of course, these ranges are only exemplary. The exact thickness of the first coating 106 or the second coating 108 will depend on the application and the conditions associated with a particular bonding operation.

[0020] Fig. Figure 5 is a flowchart of various unclaimed methods for providing a bonding tool. As those skilled in the art will appreciate, certain steps included in the flowchart may be omitted; certain additional steps may be added; and the order of the steps may vary from the illustrated order—all within the scope of the invention.

[0021] In step 502, a body portion of a wire bonding tool is provided, the body portion including a tip portion (see, for example, the body portions 100a, 102a and 104a including the respective tip portions in the Fig. 1A-1C). For example, the body portion provided in step 502 may include (or be entirely composed of) a ceramic, a metal alloy, a metal matrix composite, or a ceramic matrix composite. In optional step 504, a surface of the tip portion of the wire bonding tool is cleaned prior to step 508. The cleaning step (i.e., step 504) may include degreasing the surface of the tip portion. The cleaning step (i.e., step 504) may include plasma cleaning the surface of the tip portion. In optional step 505, the surface of the tip portion is activated after the cleaning step (i.e., step 504) but prior to step 508. This "activation" refers to increasing the surface energy of a material, thereby making the material more receptive to another material (i.e., by forming atomic bonds). This activation may be accomplished by applying energy (e.g.,of a plasma) to a surface that is to be activated.

[0022] In step 508, a first coating is applied to the tip portion (see, for example, the Fig. 2A-2C). The coating provided in step 508 may be corrosion- or wear-resistant. For example, the coating provided in step 508 (i.e., the first coating) may include (or consist entirely of) a metal, a metal compound, and a ceramic. For example, the coating provided in step 508 may include (or consist entirely of) chromium, titanium, chromium carbide, chromium nitride, and titanium nitride. For example, the coating provided in step 508 may have a thickness of 0.5 to 10 micrometers; in another example, the coating may have a thickness of 0.5 to 2 micrometers. The coating provided in step 508 may be applied using, for example, cathodic arc deposition techniques, using filtered cathodic vacuum arc deposition techniques, or using chemical vapor deposition.In optional step 510, the surface of the tip portion is activated after step 508 but before step 512.

[0023] In step 512, a second coating is applied to the first coating (see, for example, the Fig.3A-3C). The coating provided in step 512 (i.e., the second coating) may be resistant to adhesive or frictional forces. The coating provided in step 512 may be carbon-based. For example, the coating provided in step 512 may include (or consist entirely of) a diamond-like carbon, a non-hydrogenated diamond-like carbon, a tetragonal amorphous carbon, and a carbon-based coating. For example, the coating provided in step 512 may have a thickness of 0.1 to 10 micrometers; in another example, the coating may have a thickness of 0.3 to 5 micrometers.The coating provided in step 512 may be applied using, for example, sputtering techniques, filtered sputtering vacuum coating techniques, or chemical vapor deposition.

[0024] 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 changes in the details may be made within the scope and range of equivalents of the claims without departing from the invention. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 336,033

[0001] US 6,729,527

[0005] US 6,171,456

[0005]

Claims

[1] A wire bonding tool comprising: a body portion including a tip portion; a first coating applied to the tip portion; and a second coating applied to the first coating. [2] The wire bonding tool of claim 1, wherein the body portion includes at least one selection of a ceramic, a metal alloy, a metal matrix composite, and a ceramic matrix composite. [3] The wire bonding tool of claim 1, wherein the first coating is resistant to at least one selection of corrosion and wear. [4] The wire bonding tool of claim 1, wherein the first coating comprises at least one selection of a metal, a metal compound, and a ceramic. [5] The wire bonding tool of claim 1, wherein the first coating comprises at least one selection of chromium, titanium, chromium carbide, chromium nitride, and titanium nitride. [6] The wire bonding tool of claim 1, wherein the first coating has a thickness of 0.5 to 10 micrometers. [7] The wire bonding tool of claim 1, wherein the first coating has a thickness of 0.5 to 2 micrometers. [8] A wire bonding tool according to claim 1, wherein the second coating is resistant to stiction and / or friction. [9] The wire bonding tool of claim 1, wherein the second coating is carbon-based. [10] The wire bonding tool of claim 1, wherein the second coating comprises at least one selection of a diamond-like carbon coating, non-hydrogenated diamond-like carbon, tetragonal amorphous carbon, and a carbon-based coating. [11] The wire bonding tool of claim 1, wherein the second coating has a thickness of 0.1 to 10 micrometers. [12] The wire bonding tool of claim 1, wherein the second coating has a thickness of 0.3 to 5 micrometers. [13] The wire bonding tool of claim 1, wherein the body portion includes a ceramic, the first coating includes chromium, and the second coating includes a carbon-based coating. [14] The wire bonding tool of claim 13, wherein the body portion includes a ceramic matrix composite. [15] The wire bonding tool of claim 13, wherein the first coating comprises chromium nitride. [16] The wire bonding tool of claim 13, wherein the body portion comprises a ceramic matrix composite and the first coating comprises chromium nitride. [17] The wire bonding tool of claim 13, wherein the second coating comprises diamond-like carbon. [18] The wire bonding tool of claim 13, wherein the second coating comprises tetragonal amorphous carbon. [19] The wire bonding tool of claim 13, wherein the body portion comprises a ceramic matrix composite and the second coating comprises a diamond-like carbon. [20] The wire bonding tool of claim 13, wherein the body portion comprises a ceramic matrix composite and the second coating comprises a tetragonal amorphous carbon. [21] The wire bonding tool of claim 13, wherein the first coating comprises chromium nitride and the second coating comprises diamond-like carbon. [22] The wire bonding tool of claim 13, wherein the first coating comprises chromium nitride and the second coating comprises tetragonal amorphous carbon. [23] The wire bonding tool of claim 13, wherein the body portion comprises a ceramic matrix composite, the first coating comprises chromium nitride, and the second coating comprises diamond-like carbon. [24] The wire bonding tool of claim 13, wherein the body portion comprises a ceramic matrix composite, the first coating comprises chromium nitride, and the second coating comprises tetragonal amorphous carbon. [25] A wire bonding tool according to any one of claims 1 or 2, wherein the first coating is resistant to corrosion and / or wear. [26] A wire bonding tool according to any one of claims 1, 2 or 25, wherein the first coating comprises at least one of a metal, a metal compound and a ceramic. [27] A wire bonding tool according to any one of claims 1, 2, 25 or 26, wherein the first coating contains at least one selection of chromium, titanium, chromium carbide, chromium nitride and titanium nitride. [28] A wire bonding tool according to any one of claims 1, 2 or 25-27, wherein the first coating has a thickness of 0.5 to 10 micrometers. [29] A wire bonding tool according to any one of claims 1, 2 or 25-28, wherein the first coating has a thickness of 0.5 to 2 micrometers. [30] A wire bonding tool according to any one of claims 1, 2 or 25-29, wherein the second coating is resistant to adhesive and / or frictional forces. [31] A wire bonding tool according to any one of claims 1, 2 or 25-30, wherein the second coating is carbon-based. [32] A wire bonding tool according to any one of claims 1, 2 or 25-31, wherein the second coating comprises at least one of a diamond-like carbon, a non-hydrogenated diamond-like carbon, a tetragonal amorphous carbon and a carbon-based coating. [33] A wire bonding tool according to any one of claims 1, 2 or 25-32, wherein the second coating has a thickness of 0.1 to 10 micrometers. [34] A wire bonding tool according to any one of claims 1, 2 or 25-32, wherein the second coating has a thickness of 0.3 to 5 micrometers.

Images