JPH09162223A - Wire bonding capillary - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-density ceramic wire bonding capillary to be mounted on a wire bonder to weld a wire to a bonding face with an ultrasonic vibration, where the capillary has a high mechanical strength at the tip enough to transmit the vibration. SOLUTION: A welding part 54, focusing part 53 and body are unified and sintered in a mold to form the outside taper of the welding part 54 at a first angle A1, that of the converging part 53 at a second angle A2, the tape of a through-hole 42 at a third angle A3 equal or less than the second angle. The second angle is 30deg. and the first and third angles are each 10deg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonder system for ultrasonically welding an extremely thin wire to an adhesive surface, which is a tool for supplying ultrasonic vibration energy to the wire and the adhesive surface. Regarding wire bonding capillaries of ceramics,
The present invention relates to a wire bonding capillary having a high mechanical strength at its tip and capable of effectively transmitting ultrasonic vibration.

[0002]

2. Description of the Related Art When applying ultrasonic vibration to an extremely thin wire and its bonding surface by a wire bonding capillary made of high density ceramics for ultrasonic welding, the tip has a shape capable of avoiding obstacles around the bonding surface. It is important that the structure is such that the heat generated at the tip due to ultrasonic vibration is easily diffused, and various wire bonding capillaries have been proposed for this purpose. This wire bonding capillary (hereinafter, abbreviated as a tool) is used in a wire bonder system.

FIG. 3 is an explanatory view showing an example of a general wire bonder system. In FIG. 3, the wire bonder system is a tool for ultrasonically welding a conductive wire 2 to a semiconductor component etc. 3 by using a transducer 1 for generating ultrasonic vibration by high frequency power and an effective component of this ultrasonic vibration. 4 is incorporated into a wire bonding machine (not shown), and the tip of the tool 4 is vertically and horizontally (arrow) 11 and forward and backward (arrow) 1
The wire 2 is controlled to be 2 so that the wire 2 is wired on a minute bonding surface.

The tool 4 has a tapered welding side,
A cylindrical capillary type in which a thin tubular through hole 41 is provided in the inner axial direction is generally used, and the mounting side is fixed to the clamp portion 13 with the screw 14. Alternatively, a semi-cylindrical wedge type in which the through hole 41 is tilted to the welding side is rarely used. The semiconductor component 3 has an integrated circuit chip 32 on which a large number of aluminum, gold, or hybrid electrodes 31 ... 31 are vapor-deposited formed on a substrate 33 and accommodated in a package. The wire 2 is wired to the electrodes 31 ... 31 while avoiding unevenness. The wire 2 is made of an extremely thin gold wire, aluminum wire, rarely a copper wire, etc. Generally, a capillary type wire is used for the wiring of the gold wire, and a wedge type is used for the others.

A general wiring procedure for the case of wiring a gold wire by the capillary type shown in FIG. 3 will be described below.
First, the tool 4 is fixed to the transducer 1 and the wire bonding machine is put into operation. On the other hand, the wire 2 is unwound from a support tool (not shown), passed through the through hole 41 from the fixed side of the tool 4 and projected toward the welding side, and the tip thereof is formed into a spherical shape suitable for ball bonding with a melting torch (not shown). I'll do it. At that time, in order to pass the wire 2 through the tip of the tool 4 reliably, the tool 4 may be positioned with a tweezers-like object. These are preparatory preparations. Then, by controlling the wire bonding machine, the welding side of the tool 4 is moved above the arbitrary electrode 31, the spherical portion of the wire 2 is brought into contact with the surface of the electrode 31, and the axis of the tool 4 is adjusted. A predetermined pressure (arrow) 14 is applied in the direction to press the wire 2 against the electrode 31 on the welding side of the tool 4.

Next, ultrasonic vibration is generated in the transducer 1 by high-frequency power, and the effective component is generated by the tool 4
And transmitted to the tip of the wire 2. At this time, each part of the transducer 1 and the tool 4 has a unique resonance frequency adapted to its own physical characteristics, and the material and shape of the wire 2, the tool 4 and the electrode 31, the working speed of the wiring process, and the like. Each part resonates at a predetermined frequency suitable for finish quality and the like. On the other hand, if the material and shape of the ultrasonic vibration transmission path are non-uniform and there are parts with different mechanical vibration coefficients, a physically discontinuous vibration boundary surface will occur there, and energy will be lost due to the reverse conversion of vibration. Loss is generated, and the effective component of ultrasonic vibration is reduced, so that the transmission efficiency can be reduced. Therefore, each portion of the transducer 1 and the tool 4 is of a size capable of accurately supplying the vibration energy required for ultrasonic welding, and is formed of a uniform material, and the diameter is continuously changed to be smooth. It is necessary to finish on a smooth surface.

FIG. 4 is an enlarged view for explaining the type of tool in FIG. 3, FIG. 4 (a) is a general one having a tapered tip of 30 °, and FIG. 4 (b) is of 20 °. A special one with a tapered tip, FIG. 4 (c), shows a special one with a 30 ° tapered tip and approximately twice the diameter. In FIG. 4, the tool 4 has a cylindrical body portion 42.
And a tapered convergent portion 43 having a tapered longitudinal section and a tapered welded portion 44. The body portion 42 receives ultrasonic vibrations from the transducer 1 and transmits the ultrasonic vibrations to the converging portion 43. The converging portion 43 converges the ultrasonic vibrations in the tip direction, and the heat generated in the welding portion 44 is reversed to the body portion 42. The welding portion 44 diffuses and welds the wire 2 passing through the through hole 41 to the bonding surface by ultrasonic vibration.

FIG. 5 is an explanatory view for explaining the application of the tool in FIG. 4, and shows interference between the package wall of the semiconductor component 3 and the welding side of the tool 4. Package wall 3
4 rises to the outer contour of the semiconductor component 3, the wiring lead 35 penetrates the wall 34 from the outside, and the wire 2 is also ultrasonically welded to the surface thereof. At this time, the side surface on the welding side of the tool 4 hits against the wall 34, and the optimum welding position cannot be reached. Therefore, the package should be modified to remove the triangular portion composed of the two sides C1 and C2 that interferes with the wall 34. Instead, it is necessary to process the welding side of the tool 4 into a bottleneck shape and use it to avoid an interfering portion.

FIG. 6 is an explanatory view for explaining a tool having a tip of various shapes. FIG. 6 (a) is a general tool whose tip is processed into a bottleneck shape, and FIG. It shows the one processed into a wedge shape. In FIG. 6 (a), the tool 4 having a bottleneck-shaped tip only performs simple processing on the tool 4 in FIG. 3 to minimize the processing cost. That is, only the tip of the tool 4 is cut into an annular shape from a single direction with a dedicated cutting tool, and the rest is left as it is, including the through hole 41.

FIG. 7 is a sectional view as seen from the direction II in FIG. 6 (a). In FIG. 7, the bottleneck tool 4 has a through hole 41 formed in an inside cone that tapers toward the welding side, and the taper angle A is mainly 10 °, but rarely 15 °, 20 °. ° and 2
There is also 4 °, which is used properly depending on the work content. Tool 4
The mainstream material is a ceramic material, and high-density ceramics, silicon-aluminum-nitrite, etc. are being developed due to the need for cost reduction and longer life, and a composite ceramic with a sapphire chip at the tip. Various materials are used properly according to the needs. Therefore,
The tool 4 of each size, material, and shape is selected according to the size, type, and positional relationship of the semiconductor component 3 and the wire 2 to be wired, and ultrasonic vibration is efficiently transmitted, and the same tool 4 is used for a long time. It is required to be able to. Further, in the actual wiring process of semiconductor components, when changing the contents of the wiring work, it is necessary to replace the tool 4 with another type suitable for the work contents.

[0011]

However, when the wire 2 is laid on the semiconductor component 3 or the like using the tool 4 processed into the bottleneck shape, there are the following problems. (1) In the bottleneck-shaped constricted area, stress during processing is concentrated, so that the structural deterioration of the physical material structure is likely to occur, and the pressure 14 for pressing the wire 2 against the bonding surface or the ultrasonic vibration itself Easy to destroy. (2) Further, when positioning the wire 2 with a tweezers-shaped tool in FIG. 8, just before the tip (two-dot chain line) of the tool that slides the side surface of the converging part 42 reaches this constricted part, the welding part 43 Since it jumps on the shoulder (thick arrow), a strong impact is applied to the welded portion 43 (solid line), and the deteriorated tissue is more easily destroyed. (3) Furthermore, the diameter of the tool 4 changes discontinuously at the shoulder of the converging portion 42, and a physically discontinuous boundary surface is formed in which the transfer coefficient of ultrasonic vibration also changes. Since this boundary surface causes energy loss of ultrasonic vibration, the energy of vibration cannot be transmitted efficiently, and the work quality of wiring deteriorates. In view of the above-mentioned problems, it is an object of the present invention to provide a wire bonding capillary of high density ceramic, which has a high mechanical strength at the tool tip and can efficiently transmit ultrasonic vibrations.

[0012]

In order to solve the above problems, the present invention has the following means. (1) A body part that is attached to a wire bonder to transmit ultrasonic vibrations, and is formed in a tapered longitudinal sectional shape to converge the transmitted ultrasonic vibrations in the tip direction and diffuse heat in the opposite direction. Converging part and tapered longitudinal cross-section taper shape, having a through hole from the converging part side to the tip, for welding the wire passing through the through hole to the adhesive surface by focused ultrasonic vibration In a high-density ceramic wire bonding capillary composed of a welded portion, the entire welded portion, converging portion, and body portion are integrally sintered by molding to form a taper of the outer shape of the welded portion at a first angle, and the converging portion is formed. The taper of the outer shape is formed at a second angle wider than the first angle, and the taper of the through hole is formed at a third angle that is narrower than the first angle or equal to the first angle. High density Degree ceramic wire bonding capillary. (2) The first angle is 30 °, and the second and third angles are each 10 °.
The wire bonding capillary of the high-density ceramic described.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing first and second embodiments for carrying out the present invention. In FIG. 1, the new tool 5 according to the first embodiment replaces the converging part 43 of the conventional example with a new converging part 53 and the welding part 44 of the conventional example with a new welding part 54 in terms of its shape. The tool 4 is the same as the conventional tool 4 except that it is sintered.
The new welded portion 54 has a tapered outer shape at a first angle A1, and the new converged portion 53 has a tapered outer diameter at the first angle A1.
It is formed at a wider second angle A2. Also, the through hole 41
Is formed at a third angle A3 that is narrower than the first angle A1 or equal to the first angle A1. The integral sintering is
The entire welded portion 54, converging portion 53, and body portion 42 are formed on the tool 4 by molding.

That is, the outer shape of the new tool 5 does not have a constricted portion whose diameter changes discontinuously at the boundary between the new converging portion 53 and the welding portion 54. In addition, since the whole is integrally sintered by molding and manufactured, and no additional machining for grinding is performed, stress concentration due to additional machining does not exist, and cost increase due to management of machining accuracy can be suppressed. Therefore, the wall pressure of the side wall formed between the outer shape and the through hole 41 is
Since the new welding portion 54 changes uniformly and the new converging portion 53 also changes continuously, a discontinuous boundary surface does not occur in the transmission coefficient of ultrasonic vibration. Moreover, even if a tweezers-like tool is used when the wire 2 is passed through the through hole 41, the above-mentioned jump of the tool disappears and there is no impact on the new welded portion 54, so that the constriction is eliminated. Can be prevented.

In FIG. 1, in the second embodiment for carrying out the present invention, the first and third angles in the new welding portion 54 are set to 10 °, respectively, and the second angle in the new convergence portion 53 is set. The same as the first embodiment except that the angle is 30 °. That is, the wall thickness of the side wall of the new welded portion 54 between the new welded portion 54 and the through hole 41 is constant until reaching the boundary with the new convergent portion 53, and even at this boundary, it is uniform toward the new convergent portion 53. Will change to. Therefore, compared to the conventional bottleneck processed,
It can be considered that the discontinuity in the narrowed portion is so small that it can be ignored.

FIG. 2 is a list showing destructive test data using the tool of the second embodiment shown in FIG. FIG.
In this destructive test, 30 pieces of the tool 5 of the present invention and 30 pieces of the tool 4 of the conventional example were extracted and used as test samples, and the fracture strength was measured while comparing the two with the number of times of the test as a sample number. The test results are arranged and shown in the right column for each sample number. According to this test result, the minimum value, the maximum value, the average value, the standard deviation, and the intermediate value of the breaking strength of each tool 4 and 5 are as follows in each comparison.

Minimum value Maximum value Average value Standard deviation Intermediate value ==== ==== ==== ==== ===== Tool of the present invention 0.78 1.14 0.96 0.09 0 .97 Tool of Conventional Example 0.66 1.04 0.85 0.12 0.87 Even with the above test results, a remarkable improvement in fracture strength can be confirmed in the average value and the intermediate value, and the standard deviation is due to molding. It is recognized that the integral sintering achieves a uniform and uniform finish, and it is clearly shown that the new tool 5 of the present invention is actually more complete than the conventional tool 4 in terms of mechanical strength. . It should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the present invention.

[0018]

As described above, the present invention has the following effects. (1) Since there is no bottleneck-shaped constriction due to processing and stress during processing is not concentrated, there is no structural deterioration of the physical material structure, and the wire 2 is pressed against the bonding surface. It becomes difficult to destroy by the pressure 14 and the ultrasonic vibration itself. (2) When positioning the wire 2 with a tweezers-shaped tool, the shoulder of the welding portion 54 may be jumped immediately before the tip of the tool that slides the side surface of the converging portion 53 of the tool 5 reaches the welding portion 54. In addition, since no strong impact is applied to the welded portion 54, it is possible to prevent the destruction. (3) Furthermore, there is no bottleneck-shaped constricted portion, the diameter of the tool 5 changes almost continuously from the converging portion 53 to the welding portion 54, and a physically discontinuous boundary surface is formed. Disappear. Therefore, the energy loss of ultrasonic vibration due to this boundary surface is suppressed. As a result of the above (1), (2) and (3), it is possible to provide a wire bonding capillary which has a high mechanical strength at the tool tip and which can effectively transmit ultrasonic vibrations.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing first and second embodiments for implementing the present invention.

2 is a list showing destructive test data using the second embodiment in FIG. 1. FIG.

FIG. 3 is an explanatory diagram showing an example of a conventional general wire bonder system.

FIG. 4 is an enlarged view for explaining types of conventional tools in FIG.

FIG. 5 is a diagram illustrating a use of the conventional tool in FIG.

FIG. 6 is an explanatory diagram illustrating a conventional tool having various shaped tips.

FIG. 7 is a cross-sectional view as seen from the direction I-I in FIG.

FIG. 8 is an explanatory diagram for explaining conventional positioning of a wire with a tweezers-like tool.

[Explanation of symbols]

1 ... Transducer 2 ... Wire 3 ... Semiconductor component 4 ... Capillary (tool) 5 ... New capillary (new tool) 31 ... Electrode 32 ... Semiconductor chip 33 ... -Substrate 34 ... Package wall 35 ... Conductor lead 41 ... Through hole 42 ... Body part 43 ... Converging part 44 ... Welding part 53 ... New converging part 54 ...・ New weld

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[Procedure amendment]

[Submission date] March 13, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

2 is a list chart showing destructive test data using the second embodiment in FIG. 1. FIG.

Front page continuation (72) Inventor Masao Suzuki 1-34 Hongo 1-3, Hongo, Bunkyo-ku, Tokyo

Claims (2)

[Claims] 1. A body part for transmitting ultrasonic vibration by being attached to a wire bonder, and a tapered longitudinal sectional taper for converging the transmitted ultrasonic vibration in the tip direction and heat in the opposite direction. A converging part that diffuses and a tapered vertical cross-section are formed, and a through hole is provided from the converging part side toward the tip, and the wire passing through this through hole is welded to the adhesive surface by focused ultrasonic vibration. In the wire bonding capillary of high-density ceramics, which consists of the welded part, the whole of the welded part, the convergent part, and the body part is integrally sintered by molding, and the taper of the welded part outer shape is formed at the first angle, Forming the taper of the outer shape of the converging portion at a second angle wider than the first angle, and forming the taper of the through hole at a third angle equal to or smaller than the first angle. Feature Wire bonding capillary of high-density ceramics. 2. The wire bonding capillary of high density ceramics according to claim 1, wherein the first angle is 30 ° and the second and third angles are 10 °.