JP4155199B2 - Wire bonding method - Google Patents

Description

  The present invention relates to a wire bonding method for bonding wires by ultrasonic vibration, and more particularly to a method for wire bonding without resonating a wire with ultrasonic vibration of a tool.

  Conventionally, in the mounting of electronic components, a wire bonding step of electrically connecting an electronic component (for example, an IC chip on a lead frame) and an electronic component (for example, a lead of a lead frame) with a bonding wire (hereinafter referred to as a wire). Has been implemented.

  The wire bonding process is performed as follows. First, a wire is grasped with a wedge tool type tool having a wedge-shaped tip shape, and the tool is pressed against the first bond point. Then, the tool is ultrasonically vibrated while pressing the wire against the first bond point, and the wire is pressed against the first bond point by the load of the tool to join the first bond point. Thereafter, the tool is moved to the second bond point while extending the wire, and the wire is bonded to the second bond point by the same method as described above. Thus, the wire bonding process is performed, and the electronic component and the electronic component are electrically connected by the wire.

  However, in the above method, the tool is vibrated by ultrasonic vibration. For this reason, when the tool is ultrasonically vibrated at the second bond point, a phenomenon occurs in which the wire resonates with the ultrasonic vibration depending on the material and length of the wire. When the resonance vibration is transmitted from the second bond point to the first bond point via the wire, the joint portion of the first bond point is damaged. Therefore, a method for automatically avoiding the destruction of the electronic component due to such a resonance phenomenon has been proposed (for example, see Patent Document 1).

  Specifically, before performing wire bonding, a resonance range (for example, wire length) in which the wire resonates is obtained in advance and input to the wire bonding apparatus. The coordinates of the first bond point and the second bond point of the electronic component are also input to the apparatus. Then, when the wire bonding is started and the wire is bonded to the first bond point, the bonding distance is obtained from the coordinates of the first bond point where the wire bonding is performed and the second bond point where the wire is bonded next, This bonding distance is compared with the resonance range. As a result of this comparison, when the two match, the automatic bonding is stopped to prevent the wire from resonating.

When automatic bonding is stopped, the position of the second bond point is changed manually, or the wire length is changed so that the wire does not resonate, and then the wire is connected to the second bond point. Are joined. Thereafter, the process returns to automatic bonding.
JP-A-6-61312

  However, in the method of avoiding the resonance of the wire as described above, when the wire has a length that resonates with the ultrasonic vibration of the tool, the wire bonding is performed manually, and the position of the second bond point is the position by design. Will move from. Therefore, in the method of avoiding the resonance of the wire as described above, the resonance of the wire can be avoided, but the wire cannot be bonded to the second bond point as designed, so that the product yield and the wire bonding time can be reduced. Need extra energy.

  In view of the above points, an object of the present invention is to provide a wire bonding method capable of suppressing the influence of resonance caused by ultrasonic vibration on a wire when the wire is bonded to an electronic component.

  In order to achieve the above object, according to the first aspect of the present invention, the bonding tool (5, 13, 16) is ultrasonically vibrated so that the wire (9) is connected to the first bond point (8a) and the second bond point (8b). Bonding method between the first bond point and the second bond point, and a step of ultrasonically vibrating the bonding tool to bond the wire to the first bond point. A step of determining the length of the wire, and a step of moving the bonding tool to bond the wire to the second bond point. In the step of determining the length of the wire, at any frequency of ultrasonic vibration Assuming that the length at which the wire resonates is the resonance point, the length of the wire is larger than the length of the wire corresponding to the nth order resonance point and smaller than the length of the wire corresponding to the n + 1 order resonance point. Pull the wire It is characterized in that issue.

  By setting the length of such a wire, it is possible to prevent the wire from resonating with ultrasonic vibration when the wire is bonded to the second bond point. In addition, wire bonding can be performed regardless of the resonance of the wire, so it is not necessary to stretch the wire once from the first bond point, and without changing the length of the wire during bonding. Wire bonding can be performed on the street.

  Therefore, it is possible to prevent the yield of the wire bonded product from being lowered. Further, since the wire does not resonate with the ultrasonic vibration of the tool, the wire bonding is not stopped halfway, and the time required for the wire bonding can be prevented from being increased, thereby saving energy.

  According to the second aspect of the present invention, in the step of moving the bonding tool to bond the wire to the second bond point, the bonding tool (5) is provided with a wire supply port for supplying the wire on the side surface of the bonding tool. The wire is passed through a narrow hole (5a) extending from the wire supply port to the tip of the bonding tool, and from the tip of the bonding tool to the side surface opposite to the wire supply port with respect to the longitudinal central axis of the bonding tool. A guide (5b) extending in the longitudinal direction of the bonding tool is provided, the wire supply port is directed in the direction of movement of the bonding tool during bonding, and the first bond with respect to the straight line connecting the first bond point and the second bond point. After moving the bonding tool from the point at a predetermined angle, move the bonding tool to the second bond point. It is characterized by bonding the wire to the second bonding point.

  In this way, mechanical control of the tool is facilitated by moving the tool at a constant angle. Furthermore, by moving the tool at a constant angle, the shape of the wire connecting the first bond point and the second bond point can be made constant.

  Also, for example, if the tool is moved farther than the second bond point relative to the first bond point, the tool will return in the direction of the second bond point when moving the tool to the second bond point. It becomes. In such a case, the stress applied to the wire in the direction of the first bond point can be relaxed by placing the wire along the guide of the tool. Furthermore, by causing the wire to follow the guide, it is possible to prevent variations in the direction of the wire when the tool is moved to the second bond point.

  In a third aspect of the present invention, in the step of moving the bonding tool to bond the wire to the second bond point, a wire supply port for supplying the wire to the bonding tool (13) is provided on the side surface of the bonding tool. In addition, the wire supply port has an oval shape, the long axis of the oval coincides with the longitudinal direction of the tool, and the wire is inserted into the narrow hole (13a) extending from the oval wire supply port to the tip of the bonding tool. Through the straight line connecting the first bond point and the second bond point, the bonding tool is desired from the first bond point so that the bonding tool is located between the first bond point and the second bond point. After moving by the angle, the bonding tool is moved to the second bond point, and the wire is bonded to the second bond point.

  Thus, since the angle which supplies a wire can be changed by expanding a wire supply port in the longitudinal direction of a tool in the narrow hole of a tool, the angle at the time of moving a tool can be changed. Thereby, when moving a wire from a 1st bond point, it can prevent that a wire will be destroyed by being caught in a wire supply port.

  In addition, after bonding the wire to the first bond point, the tool is moved so as to be positioned between the first bond point and the second bond point, and the tool is moved to the second bond point. It is possible to prevent stress from being applied.

  In the invention described in claim 4, in the step of moving the bonding tool to bond the wire to the second bond point, the bonding tool (16) is provided with a wire supply port for supplying the wire on the side surface of the bonding tool. In addition, the wire supply port has an oval shape, the long axis of the oval coincides with the longitudinal direction of the tool, and the wire is passed through the narrow hole (16a) extending from the oval wire supply port to the tip of the bonding tool, A guide (16b) extending from the tip of the bonding tool to the longitudinal direction of the bonding tool is provided on the side surface opposite to the wire supply port with respect to the longitudinal center axis of the bonding tool, and the bonding tool is directly above the second bond point. Alternatively, a bonding tool is desired from the first bond point at a position farther than the second bond point with respect to the first bond point. After moving at an angle, it is characterized in that bonding the wire to the second bonding point by moving the bonding tool to a second bonding point.

  By using such a tool, since the angle at which the wire is supplied can be changed after the wire is bonded to the first bond, the tool can be moved at various angles. Further, since the tool is provided with the guide, it is possible to prevent the wire from being directed in various directions when the tool is moved to the second bond point.

  In addition, after bonding the wire to the first bond point, the tool is moved as far as possible with respect to the first bond point, thereby eliminating variations in the angle at which the tool is moved. Thereby, mechanical control of a tool can be made easy.

  In the invention according to claim 5, the step of determining the length of the wire joined between the first bond point and the second bond point is a length connecting the first bond point and the second bond point with a straight line. Obtaining resonance map data indicating the range of resonance of the wire relative to the relationship between the span length and the loop height of the wire joined between the first bond point and the second bond point; A step of acquiring coordinates based on a predetermined position of the component (8), a step of determining a length of the wire that does not resonate based on the resonance map and the coordinates of the electronic component, and a bonding tool for the first bond And a step of acquiring the position of the bonding tool when the wire length is extended from the point.

  By performing each process as described above, a wire can be bonded between the first bond point and the second bond point. Further, by using the resonance map indicating the range of resonance of the wire, it is possible to know the length at which the wire does not resonate with the ultrasonic vibration of the tool.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a wire bonding apparatus. As shown in this figure, the wire bonding apparatus includes a control unit 1, an ultrasonic generation unit 2, a transducer 3, an ultrasonic horn 4, a tool 5, a Z drive unit 6, and an XY drive unit 7. The electronic component 8 mounted on the XY drive unit 7 is joined by a wire 9.

  The control unit 1 outputs signals to the ultrasonic wave generation unit 2, the Z drive unit 6, and the XY drive unit 7 in order to bond the wire 9 to the electronic component 8, and drives each of them. It is a well-known microcomputer provided with the above. The electronic component 8 to be wire bonded includes, for example, a lead frame on which an IC chip is installed.

  The ultrasonic generator 2 generates a high voltage pulse necessary for ultrasonically vibrating the tool 5 when bonding the wire 9 to the electronic component 8 and outputs the signal to the transducer 3.

  The transducer 3 receives a high voltage pulse input from the ultrasonic generator 2 and generates mechanical ultrasonic vibration. The transducer 3 is composed of a plurality of ceramic plates. When a high voltage pulse is applied to a superposition of the plurality of ceramic plates, the thickness of the ceramic plate matches the cycle of the high voltage pulse. Change. Therefore, when a high voltage pulse input from the ultrasonic generator 2 is applied to the ceramic plate, ultrasonic vibrations are generated by stretching and contracting the plurality of ceramic plates to match the pulse period.

  The ultrasonic horn 4 amplifies the ultrasonic vibration generated by the transducer 3 and is composed of a rod-shaped member. The ultrasonic vibration amplified by the ultrasonic horn 4 is transmitted to the tool 5 installed at the tip of the ultrasonic horn 4.

  The tool 5 joins the wire 9 to the electronic component 8 and is of a wedge tool type having a wedge-shaped tip shape. The tool 5 is attached to the tip of the ultrasonic horn 4.

  FIG. 2 is an enlarged sectional view of the tip of the tool 5. As shown in this figure, a narrow hole 5 a for passing the wire 9 is formed at the tip of the tool 5. The narrow hole 5 a includes a wire supply port for supplying the wire 9 to the side surface of the tool 5, and extends from the wire supply port to the tip of the tool 5. Further, a guide 5 b extending from the tip of the tool 5 in the longitudinal direction of the tool 5 is provided on the side surface opposite to the wire supply port with respect to the longitudinal center axis of the tool 5.

  The narrow hole 5a is inclined at an acute angle (30 to 45 degrees) with respect to the tip of the tool 5, and the wire 9 is passed through the thin hole 5a. Further, the wire supply port is directed in the moving direction of the tool 5 during bonding.

  The wire 9 is wound around a reel (not shown), and the tip of the wire 9 is passed through the narrow hole 5a of the tool 5 as shown in FIG. Further, a stopper (not shown) for sandwiching the wire 9 is provided in the vicinity of the tip of the tool 5, and the wire 9 is supplied from the reel only when a signal from the control unit 1 is input to the stopper. It has come to be. The wire 9 is made of a material such as Al (aluminum) or Au (gold), and has a thickness of 30 to 500 μm.

  The Z drive unit 6 moves the transducer 3, the ultrasonic horn 4, and the tool 5 in the vertical direction (referred to as Z direction in the present embodiment), and includes a motor (not shown). When the Z drive unit 6 receives the signal output from the control unit 1, the Z drive unit 6 drives the motor to move the transducer 3, the ultrasonic horn 4, and the tool 5 in the Z direction.

  The XY drive unit 7 is for installing the electronic component 8, and moves the electronic component 8 in the horizontal direction (denoted as the XY direction in the present embodiment) and rotates it with respect to the central axis of the electronic component 8. The motor is provided with a motor (not shown). When receiving the signal output from the control unit 1, the XY drive unit 7 drives the motor to move or rotate the electronic component 8 in the XY direction.

  The above is the configuration of the wire bonding apparatus.

  Next, the wire bonding process performed by the wire bonding apparatus will be described with reference to the flowchart shown in FIG. This step is executed by a wire bonding apparatus and executed by a program recorded in the CPU of the control unit 1, that is, a wire bonding program.

  In step 100, a resonance map is input. First, the resonance map will be described. First, after the wire 9 is joined to the first bond point 8a (see FIG. 5, which will be described later) by ultrasonic vibration of the tool 5, the tool 5 is moved to the second bond point 8b (see FIG. 5, which will be described later). When trying to join the wire 9 to the wire 9, the wire 9 may resonate with the ultrasonic vibration of the tool 5 depending on the material and length of the wire 9. In the wire bonding apparatus, the resonance map is obtained by examining what wire length and loop height cause the resonance phenomenon by changing the wire length and loop height of the wire 9.

  Such a resonance map can be easily examined by performing a conventional wire bonding process. The resonance phenomenon varies depending on the wire bonding apparatus, the material of the wire 9, the diameter of the wire 9, and the frequency of ultrasonic waves when the tool 5 is ultrasonically vibrated. The frequency of ultrasonic vibration of the tool 5 is fixed, and under such conditions, the wire length and loop height of the wire 9 are changed to create a resonance map.

  FIG. 4 is a schematic diagram of a resonance map. The horizontal axis is the span length between the first bond point 8a and the second bond point 8b, and the vertical axis is the loop height of the wire 9 joined between the first bond point 8a and the second bond point 8b. It is. The span length corresponds to the length of a straight line between the first bond point 8a and the second bond point 8b, and the loop height of the wire 9 is a straight line between the first bond point 8a and the second bond point 8b. This corresponds to the height of the wire 9 at the highest position from the connected straight line.

  The resonance map is examined, for example, by fixing a certain span length and changing the length of the wire 9 to change the loop height. When the lengths and loop heights of various wires 9 of the wire 9 are changed, it can be seen that there are regions 10a to 10c surrounded by diagonal lines as shown in FIG. The hatched regions 10a to 10c indicate a range in which the wire 9 resonates with the ultrasonic vibration of the tool 5, and it can be seen that the region appears intermittently. This is consistent with the fact that the frequency of ultrasonic vibration of the tool 5 is constant, and therefore, when the length of the wire 9 is changed, a resonance phenomenon occurs only when the wire 9 has a certain length. In this way, a resonance map is created, and data of this resonance map is input to the memory of the control unit 1.

  When the resonance map data is input to the control unit 1 in this way, it can be understood what span length the wire 9 is and what loop length the wire 9 is not affected by resonance. That is, in this embodiment, by adjusting the length of the wire 9 so that the span length and the loop height do not resonate, the wire 9 is not affected by the ultrasonic vibration of the tool 5 in the subsequent steps. Perform wire bonding.

  In step 110, the electronic component 8 is installed in the wire bonding apparatus. That is, the electronic component 8 is installed in the XY drive unit 7 of the wire bonding apparatus.

  In step 120, coordinates are captured by image recognition. Specifically, in the electronic component 8 installed in the XY drive unit 7, a surface to be wire-bonded is photographed with a camera (not shown). Then, by performing image processing of the captured image, the coordinates of all the first bond points 8a and the second bond points 8b to be wire-bonded in the electronic component 8 are captured as data. This data is stored in the memory of the control unit 1.

  Thus, when the electronic component 8 is photographed by the camera, for example, if an IC chip or the like is installed on the lead frame, a difference occurs between the height of the outermost surface of the IC chip and the height of the outermost surface of the lead. . Therefore, the focus of the lens of the camera is changed, and the height coordinate of the electronic component 8 is also captured as data and stored in the memory of the control unit 1.

  In step 130, the wire length is determined. First, the coordinates of the first bond point 8a and the second bond point 8b to be wire-bonded are known from the data fetched in step 120. From these coordinates, the distance between the first bond point 8a and the second bond point 8b, that is, the span length is known.

  In the present embodiment, even if it is found from the image processing in step 120 that there is a difference in height between the first bond point 8a and the second bond point 8b, the difference in height in the electronic component 8 is about several hundred μm. Therefore, there is almost no difference in height between the first bond point 8a and the second bond point 8b. For this reason, the span length is simply determined between the first bond point 8a and the second bond point 8b.

  On the other hand, resonance map data is input to the control unit 1 in step 100, and the span length between the first bond point 8a and the second bond point 8b is known in step 120. For example, when the span length is L1, it corresponds to the non-resonant region 1 as shown in FIG. In such a case, the span length L1 corresponds to the wire length 1 set in the non-resonant region 1. When the span length is L2, as shown in FIG. 4, it corresponds to the non-resonant region 2 and corresponds to the wire length 2 set in the non-resonant region 2. In this way, the wire length is determined.

  In step 140, the clamp position is automatically calculated. A clamp position here is a position which moves the tool 5 in order to join the wire 9 to the 2nd bond point 8b, after joining the wire 9 to the 1st bond point 8a. FIG. 5 is a diagram illustrating a state in which the tool 5 is moved to the clamp position 11 after the wire 9 is bonded to the first bond point.

  Since the wire length is determined in step 130, the clamp position is a position separated from the first bond point 8a by the length of the wire length. An angle formed by a straight line connecting the clamp position and the first bond point 8a and a straight line connecting the first bond point 8a and the second bond point 8b is a feed angle 12 at which the tool 5 moves. The feed angle 12 is an angle at which the tool 5 is moved from the first bond point 8a as shown in FIG. The feed angle 12 corresponds to an angle formed by the narrow hole 5 a of the tool 5 and the tip surface of the tool 5.

  Since the thickness of the narrow hole 5a of the tool 5 of this embodiment is substantially the same as the thickness of the wire 9, the angle formed between the narrow hole 5a and the tip surface of the tool 5 is constant, and therefore the first bond The feed angle 12 of the tool 5 moved from the point 8a is also constant. In this way, all the clamp positions 11 to be wire-bonded are calculated based on the wire length and the angle of the narrow hole 5a of the tool 5 (that is, the feed angle 12).

  For example, if the length of the wire 9 is 1, the tool 5 is moved to the clamp position 11a. Similarly, if the length of the wire 9 is the wire length 2, the tool 5 is moved to the clamp position 11b.

  In step 150, wire bonding is performed. Specifically, first, in order to join the wire 9 to the first bond point 8a, the tool 5 is moved to the first bond point 8a. This is done by outputting a signal for moving the tool 5 to the coordinates of the first bond point 8a from the control unit 1 to the Z drive unit 6 and the XY drive unit 7.

  When the tool 5 is moved to the first bond point 8 a, a signal for joining the wire 9 is output from the control unit 1 to the ultrasonic wave generation unit 2. Receiving this signal, the ultrasonic generator 2 creates a high voltage pulse and outputs the high voltage pulse to the transducer 3. The transducer 3 that has received the high voltage pulse generates ultrasonic vibrations by applying the high voltage pulse to the ceramic plate and causing it to vibrate at the same period as the period of the high voltage pulse. The ultrasonic vibration is amplified by the ultrasonic horn 4, and the amplified ultrasonic vibration is transmitted to the tool 5, and the tool 5 is ultrasonically vibrated, so that the wire 9 is joined to the electronic component 8.

  When the wire 9 is bonded to the first bond point 8a in this manner, the wire 9 is then bonded to the second bond point 8b. First, a signal is output from the control unit 1 to a stopper that sandwiches the wire 9, and the stopper is released. Then, the tool 5 is moved to the clamp position 11 calculated in step 140. That is, the tool 5 is moved by driving the Z driving unit 6 and the XY driving unit 7 so that the tool 5 is positioned at the coordinates of the clamp position 11.

  As shown in FIG. 5, when the tool 5 is moved to the clamp position 11, the tool 5 is moved to the second bond point 8b. And the wire 9 is joined to the 2nd bond point 8b similarly to the 1st bond point 8a, and the wire 9 is cut when the tool 5 moves back diagonally upward. In this way, wire bonding at one place is performed, and thereafter, wire bonding similar to the above is performed at all positions.

  As described above, wire bonding is performed. As shown in FIG. 5, for example, when the wire length is projected in a straight line connecting the first bond point 8a and the second bond point 8b, the span length is May be shorter than the length when the wire length is projected. In such a case, the tool 5 moved to the clamp position 11 returns to the first bond point 8a side from the clamp position 11 when moving to the second bond point 8b. In such a case, as shown in FIG. 2, since the guide 5 b is provided in the tool 5, it is possible to prevent the wire 9 from dropping from the tool 5. Furthermore, since the tip of the guide 5b is rounded, the stress applied to the wire 9 when the tool 5 moves to the second bond point 8b can be relaxed.

  In this way, wire bonding is performed on the electronic component 8.

  As described above, when the wire 9 is bonded to the second bond point 8b by setting the length of the wire 9 to a length located between the region where the wire 9 resonates and the region where the wire 9 resonates, It is possible not to resonate with the sonic vibration. Moreover, since wire bonding can be performed regardless of the resonance of the wire 9 caused by ultrasonic vibration of the tool 5, wire bonding can be performed as designed.

  Therefore, it is possible to prevent the yield of the wire-bonded electronic components 8 from being lowered. Furthermore, since the wire 9 does not resonate with the ultrasonic vibration of the tool 5, it is possible to prevent the wire bonding from being stopped without increasing the time required for the wire bonding. Further, by moving the tool 5 at a constant angle, the mechanical control of the tool 5 becomes easy.

  In the present embodiment, the tool 5 is provided with a guide 5b. By providing the guide 5b in the tool 5 in this way, the wire 9 can be placed along the guide 5b when the tool 5 is moved to the second bond point 8b. Therefore, the stress applied to the wire 9 when the tool 5 moves to the second bond point 8b can be relaxed. Further, since the wire 9 is along the guide 5b, it is possible to prevent variation in the direction of the wire 9 when the tool 5 is moved to the second bond point 8b.

(Second Embodiment)
In the present embodiment, only portions different from the first embodiment will be described. This embodiment is different from the first embodiment in that the feed angle for moving the tool is not constant and the clamp position is always located between the first bond point 8a and the second bond point 8b.

  The tools necessary for carrying out this embodiment will be described. FIG. 6 is an enlarged cross-sectional view of the distal end of the tool 13 according to the second embodiment of the present invention. As shown in this figure, a narrow hole 13 a for passing the wire 9 is formed at the tip of the tool 13. The narrow hole 13 a includes a wire supply port for supplying the wire 9 to the side surface of the tool 13, the wire supply port has an oval shape, and the wire 9 extends from the oblong wire supply port to the narrow hole 13 a. Has been passed. In the present embodiment, the major axis of the oval of the wire supply port coincides with the longitudinal direction of the tool 13. Further, since the wire supply port has an oval shape, the feed angle of the wire 9 can be changed, and the angle is in an appropriate range between 10 and 80 degrees.

  Specifically, in the first embodiment, as shown in FIG. 2, since the angle formed between the narrow hole 5a of the tool 5 and the tip surface of the tool 5 is constant, the wire is connected to the first bond point 8a. When the tool 5 is moved to the clamp position after the 9 is joined, the tool 5 is moved at a constant angle. However, in this embodiment, as shown in FIG. 6, since the wire supply port of the narrow hole 13a is widened in the axial direction of the tool 13, the feed angle of the wire 9 is increased. You can change it as much as you like.

  Next, the wire bonding process in this embodiment will be described. The wire bonding step in the present embodiment is executed according to the flowchart shown in FIG. 3 as in the first embodiment. However, as described above, since the tool 13 used in the present embodiment is different from that in the first embodiment, the contents of the clamp position automatic calculation in step 140 of the first embodiment are different.

  Specifically, in the present embodiment, the clamp position is calculated so as to be always located between the first bond point 8a and the second bond point 8b. This is to minimize the stress applied to the wire 9 by the tip of the tool 13 when the tool 13 is moved from the clamp position to the second bond point 8b.

  In the present embodiment, in order to minimize the stress applied to the wire 9, as shown in FIG. 7, the clamp position 14 is always located between the first bond point 8a and the second bond point 8b. In addition, the clamp position 14 is calculated. FIG. 7 is a diagram showing a state of the wire bonding process in the present embodiment. As shown in this figure, regardless of the span length, the clamp position 14 is always located between the first bond point 8a and the second bond point 8b. In addition, an angle 15 formed by a straight line crossing the clamp position 14 and parallel to the electronic component 8 and a trajectory of the tool 13 moving from the clamp position 14 to the second bond point 8b is always less than 90 degrees.

  As described above, in the present embodiment, the tool 13 shown in FIG. 6 is used, and as shown in FIG. 7, the clamp position 14 is located between the first bond point 8a and the second bond point 8b. Thus, the clamp position 14 is calculated. The wire bonding step is executed according to the flowchart shown in FIG. 3 as in the first embodiment.

  As described above, after bonding the wire 9 to the first bond point 8a, the tool 13 is moved so as to be positioned between the first bond point 8a and the second bond point 8b, and the tool 13 is moved to the second bond point. By moving to the point 8b, it is possible to prevent the wire 9 from being stressed.

  In addition, the angle at which the tool 13 is moved can be changed by expanding the wire supply port in the long axis direction of the tool 13 in the narrow hole 13a of the tool 13. Thereby, after bonding the wire 9 to the first bond point 8a, the tool 13 can be moved so as to be positioned between the first bond point 8a and the second bond point 8b.

(Third embodiment)
In the present embodiment, only parts different from the first and second embodiments will be described. In this embodiment, the feed angle for moving the tool is not constant, unlike the first embodiment, and the clamp position is always directly above the second bond point 8b or the first bond point 8a and the second bond point. 8b is different from the first and second embodiments.

  The tools necessary for carrying out this embodiment will be described. FIG. 8 is an enlarged sectional view of the distal end of the tool 16 according to the third embodiment of the present invention. As shown in this figure, a narrow hole 16 a for passing the wire 9 is formed at the tip of the tool 16. The narrow hole 16a is provided with a wire supply port for supplying the wire 9 to the side surface of the tool 16, and the wire supply port has an oval shape. The major axis of the oval of the wire supply port coincides with the longitudinal direction of the tool 16. A guide 16 b extending from the tip of the tool 16 in the longitudinal direction of the tool 16 is provided on the side surface opposite to the wire supply port with respect to the longitudinal center axis of the tool 16.

  That is, the tool 16 used in this embodiment is a combination of the guide 5b of the tool 5 of the first embodiment and the narrow hole 13a of the tool 13 of the second embodiment.

  Next, the wire bonding process in this embodiment will be described. The wire bonding process in the present embodiment is executed according to the flowchart shown in FIG. 3 as in the first and second embodiments. However, as described above, the contents of the automatic clamp position calculation in step 140 of the first embodiment are different.

  Specifically, in the present embodiment, as shown in FIG. 9, the clamp position 17 is located directly above the second bond point 8b or farther than the second bond point 8b with respect to the first bond point 8a. Is calculated as follows. FIG. 9 is a diagram showing a state of wire bonding in the third embodiment. When the tool 16 is moved to the clamp position 17, the tool 16 returns from the clamp position 17 toward the second bond point 8b. However, the stress applied to the wire 9 is relieved by the roundness of the tip of the tool 16. Further, since the wire 9 is deformed along the guide 16b, it is prevented from falling off.

  In the present embodiment, the clamp position 17 is not positioned between the first bond point 8a and the second bond point 8b, and the clamp position is directly above the second bond point 8b or the first bond point 8a as a reference. Is set to be far from the second bond point 8b. As a result, the angle 18 formed by the straight line that crosses the clamp position 17 and is parallel to the electronic component 8 and the trajectory of the tool 16 moving from the clamp position 17 to the second bond point 8b is always 90 degrees or more.

  As described above, the feed angle of the tool 16 can be made as constant as possible by moving the clamp position 17 so as to be located immediately above the second bond point 8b or farther than the second bond point 8b. it can. Thereby, mechanical control of a wire bonding apparatus can be made easy and control of the Z drive part 6 and the XY drive part 7 can be simplified as much as possible.

  Further, by using the tool 16 of the present embodiment, the tool 16 can be moved at various angles after the wire 9 is joined to the first bond point 8a. Further, since the tool 16 is provided with the guide 16b, the wire 9 can be prevented from dropping off. The tool 16 used in the present embodiment is also applicable to the first and second embodiments.

(Other embodiments)
In the first to third embodiments, after the wire 9 is bonded to the first bond point 8a, the tools 5, 13, 16 are moved to the clamp positions 11, 14, 17 while the wire 9 is extended. Therefore, the wire length is the length from the first bond point 8a to the clamp positions 11, 14, and 17. However, when the tools 5, 13, and 16 are moved from the first bond point 8a, the tools 5, 13, and 16 cannot reach the clamp positions 11, 14, and 17 due to a mechanical error of the wire bonding apparatus. 11, 14, 17 may be displaced. In such a case, there is a possibility that the wire length becomes a length that resonates.

  In order to avoid such a case, it is conceivable to avoid changing the length of the wire length by accurately measuring the wire length. The following three methods can be cited as methods for accurately measuring the wire length.

  First, as shown in FIG. 10, there is a method of measuring the wire length based on the number of rotations of the roller 19. FIG. 10 is a diagram showing how the wire 19 measures the wire length. As shown in this figure, a roller 19 is installed on the tools 5, 13, and 16, and the number of rotations of the roller 19 is output to the controller 1 when the wire 9 is extended. When the number of rotations of the roller 19 coincides with the desired wire length, the control unit 1 outputs a signal to the stoppers installed on the tools 5, 13, and 16, and the stoppers pinch the wires 9 so that the wires 9 are not supplied. Like that. In this way, the wire length can be accurately measured using the roller 19.

  Next, there is a method for measuring a wire length by image processing. FIG. 11 is a diagram showing how the wire length is measured by image processing. As shown in this figure, the wire 9 is photographed by the camera 20, the photographed image is processed by the wire length measuring device 21, and the wire length is measured. Then, wire length data is output from the wire length measuring device 21 to the control unit 1. Thereafter, the wire length is accurately extended as described above. Thus, the wire length can be measured by image processing.

  There is also a method for measuring the wire length by measuring the resistance of the wire 9. FIG. 12 is a diagram showing a state in which the resistance between the wire 9 at the first bond point 8a and the wire 9 passed through the narrow holes 5a, 13a, 16a of the tools 5, 13, 16 is measured. As shown in this figure, the probe 22 is applied to the wire 9 of the first bond point 8a and the wire 9 passed through the narrow holes 5a, 13a, 16a of the tools 5, 13, 16 respectively, and the first bond The resistance of the wire 9 between the point 8a and the tools 5, 13, 16 is measured.

  Specifically, when the wire 9 is bonded to the first bond point 8a and the tools 5, 13, 16 are moved to the clamp positions 11, 14, 17, two probes as shown in FIG. A power source 23, an ammeter 24, and a voltmeter 25 are provided between 22, and the current flowing through the wire 9 is measured by the ammeter 24. Each value of the ammeter 24 and the voltmeter 25 is output to the control unit 1, and the control unit 1 obtains a resistance value from the relationship of resistance = voltage ÷ current. Then, it is compared with the resistance value of the exact wire length measured in advance, and when it matches this resistance value, the supply of the wire 9 is stopped. In this way, the exact wire length is measured.

  These three wire length measurement methods can be combined with the above-described first to third embodiments to measure a more accurate wire length, and the wire 9 is an ultrasonic vibration of the tools 5, 13, and 16. Can be prevented from resonating.

  In the first to third embodiments, the wire 9 is set to a length that does not resonate with the ultrasonic vibrations of the tools 5, 13, and 16. May resonate. In such a case, whether or not the wire 9 is causing a resonance phenomenon can be examined by using the ultrasonic horn 4.

  FIG. 13 is a diagram showing how the resonance of the wire 9 by the ultrasonic horn 4 is examined. As shown in this figure, when the wire 9 resonates with the ultrasonic vibration of the tools 5, 13, and 16, the vibration of the wire 9 is transmitted through the tools 5, 13, and 16 and is transmitted through the ultrasonic horn 4. ing. Therefore, by measuring the vibration of the ultrasonic horn 4 due to the vibration of the wire 9 with the horn output measuring device 26, it can be determined whether or not the wire 9 is vibrating.

  The measurement value measured by the horn output measuring instrument 26 is output to the control unit 1 and the change in the measurement value is monitored. That is, if the needle of the horn output measuring device 26 does not move, the wire 9 does not resonate. Conversely, when the needle of the horn output measuring device 26 moves, the resonance vibration of the wire 9 is transmitted to the ultrasonic horn 4 via the tools 5, 13, and 16. In this way, the resonance vibration of the wire 9 can be monitored. When the wire 9 causes resonance vibration due to a mechanical error of the wire bonding apparatus and the resonance phenomenon is detected by the horn output measuring device 26, the signal is output to the control unit 1 and the wire bonding is stopped.

  The steps shown in each figure correspond to means for executing various processes.

It is a block block diagram of the wire bonding apparatus in 1st Embodiment of this invention. It is a front-end | tip cross-sectional enlarged view of the tool used in 1st Embodiment. It is a flowchart showing the content of the wire bonding program for performing wire bonding. It is the schematic of the resonance map used when performing wire bonding. In 1st Embodiment, it is the figure which showed a mode that the tool was moved to the clamp position after the wire was joined to the 1st bond point. It is a front-end | tip cross-section enlarged view of the tool used in 2nd Embodiment. It is the figure which showed the mode of the wire bonding process in 2nd Embodiment. It is a front end cross-sectional enlarged view of a tool used in a third embodiment. It is the figure which showed the mode of the wire bonding process in 3rd Embodiment. It is the figure which showed the mode of the measurement of the wire length by a roller. It is the figure which showed the mode of the measurement of the wire length by image processing. It is the figure which showed a mode that the resistance between the wire of a 1st bond point and the wire currently passed through the fine hole of the tool was measured. It is the figure which showed a mode that the resonance of a wire was investigated with an ultrasonic horn.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Control part, 2 ... Ultrasonic wave generation part, 3 ... Transducer, 4 ... Ultrasonic horn,
5, 13, 16 ... tool, 6 ... Z drive unit, 7 ... XY drive unit, 8 ... electronic component,
8a ... 1st bond point, 8b ... 2nd bond point, 9 ... Wire.

Claims (5)

A wire bonding method for bonding a wire (9) between a first bond point (8a) and a second bond point (8b) by ultrasonically vibrating a bonding tool (5, 13, 16),
Bonding the wire to the first bond point by ultrasonically vibrating the bonding tool;
Determining a length of the wire bonded between the first bond point and the second bond point;
Moving the bonding tool to bond the wire to the second bond point;
In the step of determining the length of the wire, if the length at which the wire resonates when the ultrasonic vibration has an arbitrary frequency is defined as a resonance point, the length of the wire corresponds to the nth resonance point. A wire bonding method, wherein the wire is drawn out so as to be smaller than the length of the wire and smaller than the length of the wire corresponding to the (n + 1) th order resonance point. In the step of moving the bonding tool to bond the wire to the second bond point,
A wire supply port for supplying the wire to the bonding tool (5) is provided on the side surface of the bonding tool, and the wire is passed through a narrow hole (5a) extending from the wire supply port to the tip of the bonding tool. And a guide (5b) extending in the longitudinal direction of the bonding tool from the tip of the bonding tool on the side surface opposite to the wire supply port with respect to the central axis in the longitudinal direction of the bonding tool,
Directing the wire supply port in the direction of movement of the bonding tool during bonding,
The bonding tool is moved from the first bond point by a predetermined angle with respect to a straight line connecting the first bond point and the second bond point, and then the bonding tool is moved to the second bond point. The wire bonding method according to claim 1, wherein the wire is bonded to the second bond point. In the step of moving the bonding tool to bond the wire to the second bond point,
A wire supply port for supplying the wire to the bonding tool (13) is provided on a side surface of the bonding tool, the wire supply port is formed in an oval shape, and the major axis of the oval is in the longitudinal direction of the tool. Pass the wire through a narrow hole (13a) extending from the oblong wire supply port to the tip of the bonding tool,
From the first bond point to the straight line connecting the first bond point and the second bond point, the bonding tool is located between the first bond point and the second bond point. 2. The wire bonding method according to claim 1, wherein after the bonding tool is moved at a desired angle, the wire is bonded to the second bond point by moving the bonding tool to the second bond point. . In the step of moving the bonding tool to bond the wire to the second bond point,
A wire supply port for supplying the wire to the bonding tool (16) is provided on a side surface of the bonding tool, the wire supply port is formed in an oval shape, and the long axis of the oval is in the longitudinal direction of the tool. The wire is passed through a narrow hole (16a) extending from the oblong wire supply port to the tip of the bonding tool, and is opposite to the wire supply port with respect to the longitudinal central axis of the bonding tool. A guide (16b) extending in the longitudinal direction of the bonding tool from the tip of the bonding tool is provided on a side surface of the bonding tool;
After the bonding tool moves the bonding tool from the first bond point to a position just above the second bond point or farther than the second bond point with reference to the first bond point at a desired angle. 2. The wire bonding method according to claim 1, wherein the bonding tool is moved to the second bond point to bond the wire to the second bond point. Determining the length of the wire bonded between the first bond point and the second bond point;
The relationship between the span length, which is a length connecting the first bond point and the second bond point with a straight line, and the loop height of the wire joined between the first bond point and the second bond point Obtaining data of a resonance map indicating a range of resonance of the wire with respect to
Obtaining coordinates based on a predetermined position of the electronic component (8);
Determining the length of the wire that does not resonate based on the resonance map and the coordinates of the electronic component;
5. The method according to claim 1, further comprising: obtaining a position of the bonding tool when the bonding tool is extended from the first bond point by the length of the wire length. Wire bonding method.

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