JP4274885B2 - Ultrasonic bonding apparatus and ultrasonic bonding method - Google Patents

Description

  The present invention relates to an ultrasonic bonding apparatus that superimposes and joins metal terminals and the like of electrical components by ultrasonic vibration, and particularly relates to a structure of a horn included in the ultrasonic bonding apparatus.

In a conventional ultrasonic vibration bonding apparatus, a base material is mounted on an albin and fixed, and a material to be bonded is mounted thereon. Further, the horn is lowered and placed on the material to be joined. The horn ultrasonically vibrates the material to be bonded at a predetermined frequency while pressing the material to be bonded against the base material.
As a result, the joining surface of the base material and the material to be joined is combined with pressing and sliding due to ultrasonic vibration to remove oxides and other dirt on the metal surface. Furthermore, the plastic flow of the material is likely to occur due to frictional heat generation, and bonding is performed between metal atoms as the bonding area increases.

  In such an ultrasonic bonding apparatus, a plurality of pyramidal projections are formed on the pressing surface of the horn in order to transmit the vibration of the horn to the material to be bonded without causing slippage. In the joining step, the projection of the horn bites into the surface of the material to be joined, and the material to be joined is fixed to the horn. However, there is a problem that burrs are generated in the gap between the protrusion and the material to be bonded by the protrusions shaving the material to be bonded.

On the other hand, a method has been proposed in which the horn is pressed against the material to be joined until there is no space between the valley of the projection (uneven portion) of the horn and the material to be joined, and the burrs in the space are crushed. Yes. That is, since the protrusion of the horn deeply penetrates the material to be joined and the gap is eliminated, many burrs formed on the surface of the material to be joined are crushed between the horn and the material to be joined and It joins again (for example, refer to patent documents 1).
Japanese Patent Laid-Open No. 4-99307

  However, it is difficult to stop the joining process when there is no gap between the horn and the material to be joined, and when the horn continues to be pressed, the crushed burrs are pushed out to the outer periphery of the horn. Then, burrs are formed on the outer periphery of the horn. In particular, since the amount of bite of the horn varies depending on the location due to variations in the thickness and hardness of the materials to be joined, it is very difficult to prevent the occurrence of such burrs.

  Accordingly, an object of the present invention is to provide a horn that prevents generation of burrs in ultrasonic bonding, particularly generation of burrs in the outer periphery of the horn, an ultrasonic bonding apparatus including the horn, and an ultrasonic bonding method.

The present invention is an ultrasonic bonding apparatus that includes a horn and an anvil, and the horn vibrates a material to be bonded in one vibration direction with respect to a substrate placed on the anvil. A horn base that has a pressure surface to be pressurized and vibrates in a vibration direction, a plurality of first grooves provided along a first direction included in the pressure surface, and a second direction included in the pressure surface. A plurality of second groove portions and a protrusion provided on the pressure surface sandwiched between the first groove portion and the second groove portion, and the angle between the first groove portion and the vibration direction is different from that of the second groove portion and the vibration direction. The ultrasonic bonding apparatus is characterized in that the groove width of the first groove portion is larger than the angle between the first groove portion and the second groove portion. The angle between the first groove and the vibration direction may be larger than the angle between the second groove and the vibration direction, and the depth of the first groove may be larger than the depth of the second groove.
Here, the angle between the first groove portion and the vibration direction being larger than the angle between the second groove portion and the vibration direction means that the first groove portion is closer to the vibration direction than the second groove portion. It is formed in the direction.

  In the ultrasonic bonding using the horn in the present invention, it is possible to prevent the occurrence of burrs at the outer peripheral portion of the pressing surface. For this reason, the burr removal process is not required, and the manufacturing process and manufacturing cost can be reduced.

FIG. 1 is a schematic diagram of a horn according to the present embodiment, the whole being represented by 100. As shown in FIG. 1, in the horn 100, the upper surface of the horn base 1 is a pressure surface (in FIG. 2, the lower surface is a pressure surface) 10. The pressurizing surface 10 has a vertical groove 2 (y-axis direction) and a horizontal groove 3 (x-axis direction) in a grid pattern (matrix) to prevent slippage with the material to be joined (reference numeral 20 in FIG. 2). Is formed. A plurality of pyramidal projections 4 are formed so as to be surrounded by the vertical grooves 2 and the horizontal grooves 3.
As will be described later, the vibration direction of the head 100 is the transverse groove direction (x-axis direction). The height of the protrusion 4 is determined in consideration of the depth of protrusion of the protrusion 4 into the material to be joined necessary for bonding and the thickness of the generated burr.

In the horn 100 according to this embodiment, the width of the longitudinal groove 2 in the direction (y-axis direction) perpendicular to the ultrasonic vibration direction 30 is wider than that of the conventional structure.
Here, the width of the vertical groove 2 refers to the interval between the adjacent protrusions 4, in other words, the width of the flat portion provided between the adjacent protrusions 4 (in FIG. 1, “W”). display).

FIG. 2 is a schematic view of an ultrasonic bonding apparatus incorporating the horn 100, which is represented as a whole by 500. The ultrasonic bonding apparatus includes a horn 100 and an anvil 150. The horn 100 is disposed so that the pressure surface 10 faces downward.
Similar to the pressing surface 10 of the horn 100, a plurality of pyramidal projections 151 are provided on the upper surface of the anvil 150.

In the ultrasonic bonding apparatus 500, the two materials to be bonded 20 and the base material 21 are placed on the anvil 150, and the horn 100 is placed thereon. The protrusion 151 of the anvil 150 bites into the base material 21 and fixes the base material 21 to the anvil 150.
On the other hand, the protrusion 4 of the horn 100 bites into the material to be bonded 20 to fix the material 20 to be bonded to the horn 100.
The horn 100 is ultrasonically vibrated at a frequency of, for example, several tens of kHz in the direction of the arrow 30 while the horn 100 pressurizes the workpiece 20 and the base material 21 in the direction of the anvil 150. Thereby, the surface oxide and other dirt of the material 20 and the base material 21 are removed. Further, the frictional heat generation facilitates plastic flow of the material to be bonded 20 and the base material 21, and the bonding is performed with the expansion of the bonding area.

FIG. 3 is a schematic diagram illustrating a bonding process using the ultrasonic bonding apparatus 500. In FIG. 3, the width of the vertical groove 2 is W and the depth is H.
First, as shown to Fig.3 (a), the to-be-joined material 20 and the base material 21 are set on an anvil (not shown). In this step, the horn 100 is lowered on the anvil placed thereon. FIG. 3A shows a state in which the tip of the protrusion 4 is in contact with the material to be joined 20.

FIG. 3B is a schematic view during ultrasonic bonding. The workpiece 20 is pressed against the base material 21 by the horn 100. Further, the horn 100 is ultrasonically vibrated in the direction of the arrow 30. The frequency is, for example, several tens of kHz.
As a result, the bonding surfaces of the material to be bonded 20 and the base material 21 are slid to remove a film or the like that hinders bonding, such as an oxide film covering the bonding surface. The protrusion 4 of the horn 100 bites into the upper surface of the material 20 to be joined. The material to be joined 20 is in a state before it is plastically deformed by the biting of the protrusions 4 and burrs are generated.

  FIG. 3C is a schematic diagram at a stage where ultrasonic bonding is completed. The contact surface of the base material 21 and the material to be joined 20 is melted and joined by ultrasonic vibration. The protrusion 4 is in a state of further biting into the material 20 to be joined.

  Here, for comparison, FIG. 4 shows a perspective view of a horn having a conventional structure, which is generally indicated by 200. The horn base 201 has a vertical groove 202 and a horizontal groove 203 that are substantially orthogonal to each other. In addition, a plurality of pyramidal projections 204 are included in a portion sandwiched between the vertical groove 202 and the horizontal groove 203.

  FIG. 5 is a schematic view of a bonding process when ultrasonic bonding is performed using a horn 200 having a conventional structure. FIGS. 5 (a), 5 (b), and 5 (c) are respectively shown in FIG. 3 (a). Steps corresponding to (b) and (c) are shown.

In the conventional horn 200, when the material to be bonded 20 bites into the protrusion 204 of the horn 200 and the longitudinal groove 202 is filled with the material to be bonded 20, the material to be bonded is mainly in the y-axis direction (perpendicular to the paper surface). In other directions, the burr 205 was generated by being pushed out to the outer peripheral portion of the horn 200. Here, burrs protruding in the y-axis direction are omitted, and only burrs protruding in the x-axis direction are shown.
The amount of the burr 205 increases as the protrusion 204 bites into the material 20 to be joined. When all the projections 204 of the horn 200 bite into the material to be joined 20, the tip of the material to be joined 20 cannot stay between the horn 200 and the material to be joined 20, and the material to be joined 20 and the projections 204. The burrs 205 are formed by being pushed out to the outer peripheral portion of the horn 200 through the gap formed at the bottom of the vertical groove 202.

When the generated burr was observed in detail, it was found that the burr was mainly generated in a direction perpendicular to the vibration direction of the ultrasonic vibration.
That is, when the width of the groove perpendicular to the vibration direction of the ultrasonic vibration is 0.2 mm and the amplitude amount of the ultrasonic wave is 0.05 mm, the groove width is substantially equal for each ultrasonic vibration. In particular, it is changed from 0.2 mm to 0.15 mm. For this reason, it is considered that a metal plastic flow is generated in the direction perpendicular to the vibration direction by the amount pushed by the narrow width of the groove, which becomes a burr.

  On the other hand, in the horn 100 according to the present invention, as described above, the width of the vertical groove 2 in the direction perpendicular to the vibration direction (the y-axis direction in FIG. 1) is increased. For example, the width of the vertical groove 2 is 0.4 mm, which is twice the conventional width. In this case, if the amplitude amount of the ultrasonic vibration is 0.05 mm, the speed of the plastic flow that becomes a burr becomes about half of the conventional speed.

FIG. 6 shows the relationship between the width (W) of the longitudinal groove 2 of the horn 100 and the number of burrs generated when the horn 100 is used. As is apparent from FIG. 6, when both the vertical groove 2 and the horizontal groove 3 have a width of 0.2 mm, the number of burrs generated is 12, but the width of the vertical groove 2 should be larger than 0.3 mm. As a result, the generation of burrs can be made almost zero. That is, the generation of burrs can be prevented by increasing the width of the longitudinal groove 2 in the direction perpendicular to the vibration direction. In FIG. 6, the width of the lateral groove 3 is constant at 0.2 mm.
However, it has also been found that when the width of the lateral groove 2 is increased, the material to be bonded 20 is not sufficiently fixed during ultrasonic bonding, and the bonding strength between the material to be bonded 20 and the base material 21 is decreased.
Therefore, considering the bonding strength, it is preferable that the width of the vertical groove 2 is set to ½ or less of the pitch with respect to the pitch of the protrusions 4.

  Thus, in the ultrasonic bonding apparatus 500 according to the present embodiment, the width of the vertical groove 2 perpendicular to the vibration direction of the ultrasonic vibration is made wider than the width of the horizontal groove 3, thereby generating burrs. Can be suppressed. For this reason, in the joining process, the number of work steps for removing burrs can be reduced, and the manufacturing cost can be reduced.

  In this embodiment, the pyramid-shaped projection 4 is formed on the pressure surface 10 of the horn 100 in a grid pattern, but even if a groove (vertical groove 2 in FIG. 1) is formed only in the direction orthogonal to the vibration direction. good. Moreover, you may arrange | position in a twill shape so that the vertical groove 2 and the horizontal groove 3 may cross | intersect diagonally. However, as the angle of the groove formation direction with respect to the vibration direction (for example, the angle between the vibration direction (x-axis direction) and the formation direction of the vertical groove 2 in FIG. 1) approaches 0 degrees, the effect of preventing burr generation is greater. Get smaller. Therefore, the shape of the protrusion 4 is preferably a pyramid shape rather than a triangular pyramid or a cone shape.

  Here, the case of changing the groove width of the vertical groove 2 has been described, but the same effect can be obtained even if the depth of the vertical groove 2 is increased. That is, by making the vertical groove 2 deeper than the horizontal groove 3, it is possible to eliminate the material to be bonded 20 pushed out from the vertical groove 2 to the outer peripheral portion of the horn 100, and to prevent the generation of burrs.

Embodiment 2. FIG.
FIG. 7 is a schematic view of the horn according to the present embodiment, the whole being represented by 110. The horn 110 has substantially the same shape as the horn 100 described above, and a plurality of pyramidal projections 14 are provided at the tip of the horn base 11. Between the protrusions 14, longitudinal grooves 2 </ b> A to 2 </ b> F and lateral grooves (not shown) are provided in a substantially perpendicular direction. The vibration direction of the horn 110 is a direction substantially perpendicular to the longitudinal groove 1A and the like (lateral direction in FIG. 7).

In the horn 110, the tip of the protrusion 14 is in substantially the same plane.
A plane including the bottom surface of the vertical groove 2C and the bottom surface of the vertical groove 2D is denoted by reference numeral 40. Similarly, a plane including the bottom surfaces of the vertical grooves 2A, 2B, and 2C and a plane including the bottom surfaces of the vertical grooves 2D, 2E, and 2F are denoted by reference numerals 42 and 41, respectively. As can be seen from FIG. 7, the plane 40 is substantially parallel to the plane including the tip of the protrusion 14, while the plane 41 and the plane 42 are inclined at a predetermined angle with respect to the plane 40. That is, the vertical grooves 2C and 2D have the same depth, but the vertical grooves become deeper toward the both sides.

  FIG. 8 is a schematic diagram of an ultrasonic bonding process according to the present embodiment. When ultrasonic bonding is performed using the horn 110 according to the present embodiment, the bonding process proceeds in the same manner as in the process of FIG. However, since the surrounding vertical grooves 2A, 2B, 2E, and 2F are deeper than the central vertical grooves 2C and 2D, as shown in FIG. 8C, the vertical grooves are buried by the material to be joined. Can be reduced.

  Note that the amount of biting of the protrusion 14 with respect to the material to be bonded varies depending on the application time of the ultrasonic vibration, but since the surface pressure of the pressing surface decreases due to the filling of the gap in the groove, the biting speed also decreases at this point. . Therefore, the amount of voids that can be formed in the groove may be determined in consideration of process variations in the amount of biting. For example, when the height of the protrusion 14 is 0.7 mm, the step (vertical distance) between the vertical groove 2A and the vertical groove 2C is preferably about 0.2 mm or more.

As described above, in the ultrasonic bonding apparatus according to the second embodiment, the plane connecting the bottoms of the longitudinal grooves is formed of the three surfaces 40, 41, and 42, so that the generation of burrs can be prevented. As a result, the burr removing step can be omitted in the joining step, and the manufacturing cost can be reduced.
The plane connecting the bottoms of the longitudinal grooves can be 4 or more.

  Here, the case where the plane connecting the bottoms of the longitudinal grooves is composed of the three surfaces 40, 41, and 42, and the tip is included in one plane has been described. However, the surface connecting the tip portions can be a multi-face structure. In short, even if the central vertical groove is filled with the material to be joined, it is sufficient that the surrounding vertical grooves are not filled with the material to be joined.

It is a perspective view of the horn concerning Embodiment 1 of this invention. 1 is a schematic diagram of an ultrasonic bonding apparatus according to a first embodiment of the present invention. It is the schematic of the ultrasonic joining process concerning Embodiment 1 of this invention. It is a perspective view of the horn concerning a conventional structure. It is the schematic of the conventional ultrasonic bonding process. This is the relationship between the width of the groove formed in the horn and the number of flashes generated. It is the schematic of the horn concerning Embodiment 2 of this invention. It is the schematic of the ultrasonic joining process concerning Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Horn base part, 2 vertical groove, 3 horizontal groove, 4 protrusion part, 10 pressurization surface, 20 to-be-joined material, 21 base material, 30 ultrasonic vibration direction, 100 horn, 150 anvil, 500 ultrasonic bonding apparatus.

Claims (7)

An ultrasonic bonding apparatus including a horn and an anvil, wherein the horn vibrates a material to be bonded in one vibration direction with respect to a base material placed on the anvil,
The horn
A horn base having a pressing surface for pressing a material to be joined and vibrating in the vibration direction;
A plurality of first grooves provided along a first direction included in the pressure surface;
A plurality of second grooves provided along a second direction included in the pressure surface;
Including a projection provided on the pressure surface sandwiched between the first groove and the second groove,
The angle between the first groove and the vibration direction is larger than the angle between the second groove and the vibration direction, and the groove width of the first groove is larger than the groove width of the second groove. Ultrasonic bonding apparatus characterized by. An ultrasonic bonding apparatus including a horn and an anvil, wherein the horn vibrates a material to be bonded in one vibration direction with respect to a base material placed on the anvil,
The horn
A horn base having a pressing surface for pressing a material to be joined and vibrating in the vibration direction;
A plurality of first grooves provided along a first direction included in the pressure surface;
A plurality of second grooves provided along a second direction included in the pressure surface;
Including a plurality of protrusions provided on the pressing surface sandwiched between the first groove and the second groove,
An angle between the first groove and the vibration direction is larger than an angle between the second groove and the vibration direction, and the depth of the first groove is larger than the depth of the second groove. Ultrasonic bonding apparatus characterized. An ultrasonic bonding apparatus including a horn and an anvil, wherein the horn vibrates a material to be bonded in one vibration direction with respect to a base material placed on the anvil,
The horn
A horn base having a pressing surface for pressing a material to be joined and vibrating in the vibration direction;
A plurality of first grooves provided along a first direction included in the pressure surface;
A plurality of second grooves provided along a second direction included in the pressure surface;
Including a plurality of protrusions provided on the pressing surface sandwiched between the first groove and the second groove,
An angle between the first groove and the vibration direction is larger than an angle between the second groove and the vibration direction, and the first plane including the tips of the plurality of protrusions is The ultrasonic bonding apparatus, wherein the second plane including the bottoms of the plurality of first grooves is inclined.   The plane including the plurality of second groove portions includes the second plane and a third plane including the bottoms of the plurality of first groove portions unlike the second plane, and the third plane is the first plane. The ultrasonic bonding apparatus according to claim 3, wherein the ultrasonic bonding apparatus is inclined with respect to the second plane.   The ultrasonic bonding apparatus according to claim 1, wherein the second direction substantially coincides with the vibration direction, and the first direction is a direction substantially orthogonal to the vibration direction.   The ultrasonic bonding apparatus according to claim 1, wherein the protrusion has a pyramid shape. An ultrasonic bonding method using the ultrasonic bonding apparatus according to any one of claims 1 to 6 ,
Placing the substrate on the anvil;
Placing the material to be joined on the substrate, and placing the horn so that the pressure surface is in contact with the material;
A bonding step of vibrating the bonded material in a vibration direction while pressing the bonded material with the pressing surface,
The bonding step is a step of vibrating the material to be bonded while maintaining a gap that is not buried in the material to be bonded in a groove provided on the pressure surface at a predetermined angle with respect to the vibration direction. Ultrasonic bonding method.

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