Mounting apparatus and method for detecting displacement of bonding head provided in mounting apparatus

Abstract

To provide a mounting device and the like capable of accurately detecting the amount of displacement of a bonding head in the forward / backward direction and the amount of displacement in the rotation direction.SOLUTION: A mounting device includes a bonding head having a cylindrical side surface, a support member supporting the bonding head, a first actuator moving the bonding head back and forth in its axial direction, a second actuator rotating the bonding head about its axis, a first scale provided on the cylindrical side surface and detecting axial displacement of the bonding head, a second scale provided on the cylindrical side surface and detecting axial displacement of the bonding head, a first sensor head reading the first scale and outputting a first detection signal corresponding to the axial displacement of the bonding head, and a second sensor head supported by the support member, reading the second scale, and outputting a second detection signal corresponding to the axial displacement of the bonding head.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mounting apparatus and a method for detecting displacement of a bonding head provided in the mounting apparatus. [Background technology]

[0002] For example, in mounting devices such as die bonders used in manufacturing semiconductor chips, it is necessary to control the position of a bonding head that has a semiconductor chip attached to its tip and place it accurately on a die pad of a lead frame placed on a stage. For this purpose, techniques have been proposed for precisely measuring the positions of the bonding head and the attached semiconductor chip relative to the die pad (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-036068 A Summary of the Invention [Problem to be solved by the invention]

[0004] Even if the relative positional relationship immediately before placing the semiconductor chip on the lead frame can be accurately measured, unless the bonding head that sucks the semiconductor chip can be displaced with precision, the semiconductor chip cannot be correctly placed on the target position on the lead frame. In particular, when the bonding head is directly driven and displaced immediately before placing the semiconductor chip on the lead frame, it is particularly important to detect the amount of displacement with precision. This requirement is also applicable to flip chip bonders that mount semiconductor chips on target positions on a substrate.

[0005] In a typical mounting device, the bonding head is rotated via a link mechanism or a gear train, so the output shaft of the actuator and the rotation shaft of the bonding head do not coincide. In addition, the drive mechanism that moves the bonding head linearly and the drive mechanism that rotates the bonding head may be structured hierarchically so that they are stacked on top of each other with respect to the bonding head. Therefore, when trying to calculate the rotation amount of the bonding head by detecting the rotation amount of the actuator's output shaft, an accurate value cannot always be obtained due to play in the power transmission mechanism and accumulated errors due to the hierarchical structure.

[0006] The present invention has been made to solve such problems, and provides a mounting device etc. that can accurately detect the amount of displacement of a bonding head in the forward / backward direction and the amount of displacement in the rotational direction. [Means for solving the problem]

[0007] A mounting device in a first aspect of the present invention comprises a bonding head having a cylindrical side, a support member that supports the bonding head so that it can move back and forth in an axial direction along a central axis of the cylindrical side, and rotate around the central axis, a first actuator that moves the bonding head back and forth in the axial direction, a second actuator having an output axis that does not coincide with the central axis and rotates the bonding head around the axis, a first scale provided on the cylindrical side for detecting displacement of the bonding head in the axial direction, a second scale provided on the cylindrical side for detecting displacement of the bonding head around the axis, a first sensor head that reads the first scale and outputs a first detection signal corresponding to the displacement of the bonding head in the axial direction, and a second sensor head supported by the support member that reads the second scale and outputs a second detection signal corresponding to the displacement of the bonding head around the axis.

[0008] In addition, a displacement detection method in a second aspect of the present invention is a displacement detection method for a bonding head provided in a mounting apparatus, comprising: a second output step in which, when the bonding head having a cylindrical side surface is displaced around a central axis of the cylindrical side surface relative to a support member supporting the bonding head using a second actuator having an output axis that does not coincide with the central axis, a second sensor head supported by the support member reads a second scale provided on the cylindrical side surface and outputs a second detection signal corresponding to the displacement of the bonding head around the axis; and a first output step in which, when the bonding head is displaced in an axial direction along the central axis relative to the support member using a first actuator, a first sensor head reads a first scale provided on the cylindrical side surface and outputs a first detection signal corresponding to the axial displacement of the bonding head. Effect of the Invention

[0009] According to the present invention, it is possible to provide a mounting device etc. that can accurately detect the amount of displacement of a bonding head in the forward / backward direction and the amount of displacement in the rotation direction. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing a schematic view of a main part of a flip chip bonder according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a system configuration diagram of a flip chip bonder. [Diagram 3] FIG. 2 is a perspective view showing a bonding head and two sensor heads. [Figure 4] FIG. 2 is a diagram illustrating a scale film. [Diagram 5] FIG. 11 is a flow chart for explaining a processing procedure of a calculation processing unit when the bonding head is directly displaced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential as means for solving the problems.

[0012] FIG. 1 is a perspective view showing a schematic view of a main part of a flip chip bonder 100 according to the present embodiment. The flip chip bonder 100 is an example of a mounting device incorporating a position control device, and is a bonding device that mounts a semiconductor chip 310 having electrodes formed on one surface to electrodes of a substrate 330. Note that the perspective view of the flip chip bonder 100 shown in FIG. 1 is a diagram showing elements related to position control in a case where the bonding head 110 is directly displaced, and does not show all of the configurations necessary for the flip chip bonder 100 to perform its functions. In addition, the mounting device is not limited to a flip chip bonder, and may be a die bonder that places and bonds a semiconductor chip to a die pad of a lead frame.

[0013] The flip chip bonder 100 mainly comprises a bonding head 110, a holder base 120, a linear motion mechanism 130, a rotation mechanism 140, a holder block 150, and a sensor plate 160. The bonding head 110 adsorbs a semiconductor chip 310 to its tip, places it on a mounting area 320 of a substrate 330 placed on a stage 220, and bonds it by applying pressure and heat. The bonding head 110 in this embodiment has an overall cylindrical shape, and the central axis A of the cylindrical side surface is c As shown in the figure, is parallel to the Z axis. In this embodiment, as shown in the figure, the Z axis direction is the vertical direction (height direction), and the X axis direction and the Y axis direction are planar directions, and are defined to be perpendicular to each other.

[0014] The holder base 120 is a support member that supports the bonding head 110 via the holder block 150. The holder base 120 also directly or indirectly supports the linear motion mechanism 130 and the rotation mechanism 140. The holder base 120 can be moved in its entirety in the vertical direction and in the planar direction as shown by the white arrow in FIG. 1 by driving a holder actuator not shown in FIG. 1 in the space above the stage 220. By controlling the movement of the entirety in this way, the holder base 120 can move the bonding head 110 that has adsorbed the semiconductor chip 310 by the chip supply device to the top of the mounting area 320 on which the bonding head 110 is to be placed, for example. It is preferable that the bonding head 110 remains stationary relative to the holder base 120 during the movement of the entirety of the holder base 120.

[0015] The linear motion mechanism 130 moves the bonding head 110 along the central axis A c The linear motion mechanism 130 is an advance / retract fine movement mechanism for advancing and retreating within a set very small distance range (for example, ±0.5 mm from a reference position) in an axial direction (z direction indicated by the arrow in the figure) along the axis. The linear motion mechanism 130 includes a first actuator 131, for example a motor, and a transmission mechanism that transmits the output of the first actuator 131. The transmission mechanism is constituted by a gear train including, for example, a rack and pinion gear.

[0016] The rotation mechanism 140 rotates the bonding head 110 around the central axis A c The first actuator 131 and the second actuator 141 may be a voice coil motor, an air cylinder, a hydraulic cylinder, a linear motor, or the like that omits the transmission mechanism and drives the bonding head 110 in the axial direction or around the axis.

[0017] The holder block 150 is attached to the holder base 120 and the bonding head 110 is aligned along the central axis A. c The center axis A is the axis along which the c The holder block 150 is a guide member that supports and guides the bonding head 110 so that it can rotate about its axis. The holder block 150 may be formed integrally with the holder base 120. The holder block 150 has an opening window 151 for exposing a part of the cylindrical side surface of the bonding head 110 to the outside. The opening window 151 has a shape surrounded by a rectangular frame in FIG. 1, but may have any shape as long as the holder block 150 maintains its function of supporting and guiding the bonding head 110.

[0018] The sensor plate 160 is a plate-like member that is installed on the holder block 150 so as to face the cylindrical side surface of the bonding head 110 and cover at least a part of the opening window 151. The sensor plate 160 supports the first sensor head 161 and the second sensor head 162 so that their sensing parts face the cylindrical side surface of the bonding head 110. The first sensor head 161 outputs a first detection signal according to the displacement of the bonding head 110 in the axial direction (advance and retreat direction). The second sensor head 162 outputs a second detection signal according to the displacement of the bonding head 110 around the axis (rotation direction). In FIG. 1, the first sensor head 161 and the second sensor head 162 are supported by the sensor plate 160 so as to protrude toward the inside of the opening window 151.

[0019] By arranging the first sensor head 161 and the second sensor head 162 on the sensor plate 160 in this manner, a displacement calculation unit (described later) can calculate the amount of axial displacement and the amount of axial displacement of the bonding head 110 relative to the holder base 120. In other words, it can be said that the first sensor head 161 and the second sensor head 162 are substantially supported by the holder base 120.

[0020] 2 is a system configuration diagram of the flip chip bonder 100. The control system of the flip chip bonder 100 is mainly composed of an arithmetic processing unit 170, a holder actuator 121, a first actuator 131, a second actuator 141, a first sensor head 161, and a second sensor head 162. The arithmetic processing unit 170 is a processor (CPU: Central Processing Unit) that controls the flip chip bonder 100 and executes programs. The processor may be configured to cooperate with an arithmetic processing chip such as an ASIC (Application Specific Integrated Circuit) or a GPU (Graphics Processing Unit).

[0021] The arithmetic processing unit 170 also plays a role as a functional arithmetic unit that executes various calculations according to the processing instructed by the position control program. Specifically, the arithmetic processing unit 170 can function as a displacement calculation unit 171 and a drive control unit 172. The displacement calculation unit 171 receives a first detection signal output by the first sensor head 161 and processes the first detection signal to calculate the amount of displacement in the axial direction (advance / retract direction) of the bonding head 110 relative to the holder base 120. The displacement calculation unit 171 also receives a second detection signal output by the second sensor head 162 and processes the second detection signal to calculate the amount of displacement around the axis (rotation direction) of the bonding head 110 relative to the holder base 120. The displacement calculation unit 171 also receives a position detection signal from a position sensor (not shown) and processes the position detection signal to calculate the three-dimensional coordinates of the holder base 120 at the reference position.

[0022] In the fine movement control, the drive control unit 172 determines a target amount of movement by which the semiconductor chip 310 should be displaced to reach the mounting area 320 on which the semiconductor chip 310 is to be placed, and also determines a target amount of rotation by which the semiconductor chip 310 should be displaced to be placed in the mounting area 320 in a correct posture. The drive control unit 172 then adjusts the semiconductor chip 310 to a target posture by transmitting a drive signal to the second actuator 141 while successively comparing the target amount of rotation with the amount of displacement around the axis calculated by the displacement calculation unit 171. Furthermore, the drive control unit 172 then transmits a drive signal to the first actuator 131 while successively comparing the target amount of movement with the amount of displacement in the axial direction calculated by the displacement calculation unit 171, thereby placing the semiconductor chip 310 at a target position in the mounting area 320. In the overall movement control, the drive control unit 172 also determines a target movement position of the holder base 120. Then, the drive control unit 172 causes the holder base 120 to reach the movement target position by sending a drive signal to the holder actuator 121 while successively comparing the movement target position with the three-dimensional coordinates of the holder base 120 calculated by the displacement calculation unit 171.

[0023] Next, the displacement detection sensor employed in this embodiment and its arrangement will be described. Fig. 3 is a perspective view that shows a bonding head 110 and two sensor heads (a first sensor head 161 and a second sensor head 162). In Fig. 3, the two sensor heads are drawn farther apart than they actually are, and the sensor plate 160 that supports them is omitted, so that the relationship between the two sensor heads and the opposing scale films 113 can be easily understood.

[0024] The first sensor head 161, paired with the first scale 113a drawn on the opposing scale film 113, constitutes a z-axis encoder that detects the amount of displacement in the axial direction (advance / retract direction) of the central axis Ac of the bonding head 110. The z-axis encoder is a reflective linear encoder that receives the reflected light that is projected from the first sensor head 161 and reflected by the first scale 113a with a photodiode and outputs a first detection signal that is generated based on the intensity of the reflected light and corresponds to the displacement in the axial direction.

[0025] The second sensor head 162 is paired with the second scale 113b drawn on the opposing scale film 113, and is aligned with the central axis A of the bonding head 110. c The z-axis encoder is a θ-axis encoder that detects the amount of displacement around the axis (rotation direction). The θ-axis encoder is a reflective linear encoder that receives the light projected from the second sensor head 162 and reflected by the second scale 113b with a photodiode and outputs a second detection signal corresponding to the displacement around the axis, which is generated based on the intensity of the light. In this embodiment, both the z-axis encoder and the θ-axis encoder employ such a reflective linear encoder, but any type of sensor may be employed as long as it is a displacement sensor that outputs a detection signal corresponding to the displacement by opposing the scale and the sensor head. For example, a magnetic encoder may be used in which the scale is composed of a magnet and the change is detected by a magnetic sensor provided in the sensor head.

[0026] At least a portion of the side surface of the bonding head 110 is aligned with the central axis A. c The scale film 113 may be attached directly to the cylindrical side surface 110a, but in this embodiment, in consideration of ease of attachment, the scale film 113 is attached indirectly via a scale block 112.

[0027] The scale block 112 has a central axis A when attached to the bonding head 110. cThe scale block 112 has an outer surface 112a which is an arcuate surface equidistant from the bonding head 110 and which substantially forms the cylindrical side surface of the bonding head 110. The scale film 113 is adhered to this outer surface 112a. Therefore, when the scale block 112 is attached to the bonding head 110, the scale film 113 adhered to the outer surface 112a is substantially provided on the cylindrical side surface of the bonding head 110. In other words, the first sensor head 161 can directly detect the displacement of the bonding head 110 in the forward / backward direction by reading the change in the first scale 113a, and the second sensor head 162 can directly detect the displacement of the bonding head 110 in the rotational direction by reading the change in the second scale 113b. Even if the bonding head 110 does not have a cylindrical side surface, or even if the bonding head 110 has a cylindrical side surface but the scale block 112 is not attached to the cylindrical side surface, the outer surface 112a of the scale block 112 attached to the bonding head 110 is aligned with the central axis A, which is the axis of rotation of the bonding head 110. c If the outer surface 112a is an arcuate surface equidistant from the bonding head 110, the bonding head 110 will have a substantially cylindrical side surface, and the scale film 113 may be attached to the outer surface 112a.

[0028] In a mounting device, it is difficult to directly rotate the bonding head by aligning the output axis of the actuator for rotation (second actuator 141 in this embodiment) with the central axis of the bonding head. cIn many cases, the bonding head is rotated by combining an actuator having an output shaft that does not coincide with the center axis of the bonding head and a transmission mechanism that transmits the output of the actuator. In a conventional mounting device configured in this way, the amount of rotation of the output shaft of the actuator is detected by a rotary encoder, and the amount of rotation of the bonding head is calculated using a conversion formula. However, when calculating the amount of rotation of the bonding head in this way, an accurate value cannot always be obtained due to play in the transmission mechanism and installation errors. There are also attempts to fix the actuator to the linear motion mechanism and make its output shaft coincide with the central axis of the bonding head, but in this configuration, the rotation mechanism is structured so as to be stacked on the linear motion mechanism, so errors accompanying the operation of the linear motion mechanism are also accumulated, and it is still not possible to obtain an accurate amount of rotation of the bonding head.

[0029] In contrast to such conventional techniques, according to the flip chip bonder 100 of this embodiment, both the first sensor head 161 and the second sensor head 162 are substantially supported by the holder base 120 without a drive mechanism therebetween, and both the first scale 113a and the second scale 113b are substantially attached to the cylindrical side surface of the bonding head 110. Therefore, the axial displacement and the axial displacement of the bonding head 110 can be directly detected, and the respective displacement amounts can be obtained more accurately than in the conventional mounting device. In this embodiment, the displacement calculation unit 171 calculates the axial displacement amount and the axial displacement amount based on the first detection signal and the second detection signal, but the axial velocity and the axial angular velocity of the bonding head 110 may be calculated by observing the change in each detection signal per short time.

[0030] 4 is a diagram showing a schematic diagram of the scale film 113. In this embodiment, the first scale 113a and the second scale 113b are drawn adjacent to each other on one film. The first scale 113a is a scale for detecting the axial displacement of the bonding head 110, and therefore first line segments having a length L1 perpendicular to the axial direction (advance / retract direction) are arranged in a number corresponding to the set resolution and the displacement width W1 in the advance / retract direction. The displacement width W1 is 1.0 mm if it is ±0.5 mm with respect to the reference position as described above.

[0031] Since second scale 113b is a scale for detecting the displacement around the axis of bonding head 110, second line segments of length L2 perpendicular to the axis (rotation direction) are arranged in a number corresponding to the set resolution and displacement width W2 in the rotation direction. If the radius of curvature of outer surface 112a, which is the adhesion surface of scale film 113, is 8 mm, for example, and the rotation angle is ±5 degrees with respect to the reference angle as described above, the displacement width W2 is 2π×8×10 / 360 mm.

[0032] Here, in the case where the first scale 113a and the second scale 113b are disposed adjacent to each other, even if the projection light from the first sensor head 161 is projected to any location within the displacement width W1, in order for the second sensor head 162 to detect the amount of displacement when the bonding head 110 is rotated, the length L2 of the second line segment needs to be equal to or greater than the displacement width W1. Similarly, even if the projection light from the second sensor head 162 is projected to any location within the displacement width W2, in order for the first sensor head 161 to detect the amount of displacement when the bonding head 110 advances or retreats, the length L1 of the first line segment needs to be equal to or greater than the displacement width W2. In this embodiment, from the viewpoint of making the scale film 113 as small as possible, L1=W2 and L2=W1 are set. That is, the length L1 of each of the multiple first line segments is equal to the spacing W2 between the line segments at both ends of the multiple second line segments, and the length L2 of each of the multiple second line segments is equal to the spacing W1 between the line segments at both ends of the multiple first line segments.

[0033] In this embodiment, the first scale 113a and the second scale 113b are arranged side by side on one film in order to draw the first line segment and the second line segment so as to be orthogonal to each other with high accuracy, but the arrangement of the first scale 113a and the second scale 113b is not limited to this example. The first scale 113a and the second scale 113b may be formed separately and attached to the outer surface 112a or the cylindrical side surface 110a with their orientations adjusted. In addition, in a case where the first sensor head 161 and the second sensor head 162 are supported by different support members, the first scale 113a and the second scale 113b may be installed separately so as to face the respective sensor head positions.

[0034] Next, the processing procedure of the arithmetic processing unit when directly displacing the bonding head 110 will be described. Fig. 5 is a flow diagram explaining the processing procedure. The illustrated flow starts from the point when the bonding head 110 is moved to the upper part of the mounting area 320 to be placed by the whole movement control, and the target amount of advance / retraction and the target amount of rotation of the bonding head 110 thereafter are determined.

[0035] In step S101, the drive control unit 172 transmits a drive signal to the second actuator 141 to rotate the bonding head 110. In step S102, the displacement calculation unit 171 acquires a second detection signal output by the second sensor head 162 after reading the second scale 113b, and in step S103, calculates the amount of displacement around the axis from the second detection signal.

[0036] In step S104, the displacement calculation unit 171 determines whether the calculated displacement amount reaches the determined rotation target amount. If it determines that it has not reached the target amount, the process returns to step S101. If it determines that it has reached the target amount, the process causes the drive control unit 172 to stop transmitting the drive signal to the second actuator 141, and the process proceeds to step S105.

[0037] In step S105, the drive control unit 172 transmits a drive signal to the first actuator 131 to move the bonding head 110 forward or backward. In step S106, the displacement calculation unit 171 acquires a first detection signal output by the first sensor head 161 after reading the first scale 113a, and in step S107 calculates the amount of displacement in the axial direction from the first detection signal.

[0038] In step S108, the displacement calculation unit 171 judges whether the calculated displacement amount has reached the determined target amount of movement. If it has not reached the target amount, the process returns to step S105. If it has reached the target amount, the drive control unit 172 stops sending a drive signal to the first actuator 131, and the process of placing the semiconductor chip 310 on the mounting area 320 that is the placement target is terminated. [Explanation of symbols]

[0039] 100...flip chip bonder, 110...bonding head, 110a...cylindrical side surface, 112...scale block, 112a...outer surface, 113...scale film, 113a...first scale, 113b...second scale, 120...holder base, 121...holder actuator, 130...linear motion mechanism, 131...first actuator, 140...rotation mechanism, 141...second actuator, 150...holder block, 151...opening window, 160...sensor plate, 161...first sensor head, 162...second sensor head, 170...arithmetic processing unit, 171...displacement calculation unit, 172...drive control unit, 220...stage, 310...semiconductor chip, 320...mounting area, 330...lead frame

Claims

1. a bonding head having a cylindrical side surface; a support member that supports the bonding head so that the bonding head can move back and forth in an axial direction along a central axis of the cylindrical side surface and can rotate around the central axis; a first actuator that moves the bonding head back and forth in the axial direction; a second actuator having an output shaft not coinciding with the central axis and rotating the bonding head about the output shaft; a first scale provided on a side surface of the cylinder for detecting a displacement of the bonding head in the axial direction; a second scale provided on a side surface of the cylinder for detecting a displacement of the bonding head around the axis; a first sensor head that reads the first scale and outputs a first detection signal corresponding to a displacement of the bonding head in the axial direction; a second sensor head supported by the support member, the second sensor head reading the second scale and outputting a second detection signal corresponding to a displacement of the bonding head about the axis; A mounting device comprising:

2. The mounting apparatus according to claim 1 , wherein the first scale and the second scale are disposed adjacent to each other on a side surface of the cylinder.

3. the first scale is formed by a plurality of first line segments, the second scale is formed by a plurality of second line segments, 3. The mounting device according to claim 2, wherein a length of each of the plurality of first line segments is equal to a spacing between the line segments at both ends of the plurality of second line segments, and a length of each of the plurality of second line segments is equal to a spacing between the line segments at both ends of the plurality of first line segments.

4. 4. The mounting device according to claim 2, wherein the first scale and the second scale are integrally formed and attached to the side surface of the cylinder.

5. A method for detecting displacement of a bonding head provided in a mounting apparatus, comprising: a second output step in which, when the bonding head having a cylindrical side surface is displaced around a central axis of the cylindrical side surface relative to a support member supporting the bonding head by using a second actuator having an output axis that does not coincide with the central axis, a second sensor head supported by the support member reads a second scale provided on the cylindrical side surface and outputs a second detection signal corresponding to the displacement of the bonding head around the axis; a first output step in which, when the bonding head is displaced in an axial direction along the central axis relative to the support member by a first actuator, a first sensor head reads a first scale provided on a side surface of the cylinder and outputs a first detection signal corresponding to the displacement of the bonding head in the axial direction; A displacement detection method comprising:

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