JP4265461B2 - Electronic component mounting device - Google Patents

Description

  The present invention relates to an electronic component mounting apparatus for mounting electronic components such as semiconductor bare chips and electronic circuit packages on a substrate.

  2. Description of the Related Art Conventionally, when an electronic component such as a bumped semiconductor bare chip is mounted on a substrate, a method of applying a load to the electronic component and pressing the bump against an electrode on the substrate has been adopted. According to this method, since it is necessary to manage the load value applied to each bump within a certain range, a load sensor such as a load cell is used to measure the load applied to the electronic component. Installation is done.

  The configuration of a conventional electronic component mounting apparatus is shown in FIG. In the conventional electronic component mounting apparatus 100, a moving block that moves in the Z direction is divided into a first moving block 110 and a second moving block 120, and a nut portion 121 provided in the second moving block 120 is rotated by a motor 150. The drive screw 151 is engaged with the driven feed screw 151. Further, the first moving block 110 and the second moving block 120 are connected to each other by a spring 122, and a load cell 130 that is a load sensor is provided between the first moving block 110 and the second moving block 120. . A slider 111 is provided on a side surface of the first moving block 110 and slides on a guide rail 112 provided in the Z direction.

  At the lower end of the first moving block 110, a shaft 113 whose central axis is disposed in the Z direction and a holding head 115 for sucking and holding the electronic component 101 by negative pressure are sequentially provided. A table 140 that can move in the X direction and the Y direction is provided below the holding head 115, and the substrate 102 is placed on the table 140. The output of the load cell 130 is input to the control unit 160, and the control unit 160 controls the driving of the motor 150 while monitoring the output of the load cell 130.

  When mounting the electronic component 101 on the substrate 102, the motor 150 is rotationally driven in a predetermined direction to lower the second moving block 120 and the first moving block 110 in the Z direction. When the electronic component 101 comes into contact with the substrate 102, the load detected by the load cell 130 gradually increases, and the electronic component 101 is pressurized. At this time, for example, by applying ultrasonic waves while pressing the electronic component 101 with a constant load, the bumps 101a provided on the bottom of the electronic component 101 are coupled to the wiring pattern on the substrate 102 and mounted. Thereafter, the holding head 115 is separated from the electronic component 101, and the second moving block 120 and the first moving block 110 are raised in the Z direction.

  As a prior art related to a conventional electronic component mounting apparatus, Patent Document 1 discloses that the first moving block and the second moving block are connected via an air cylinder instead of connecting the first moving block and the second moving block with a spring. Discloses an electronic component mounting apparatus. Further, Patent Document 2 uses a voice coil motor instead of a motor and a screw feed mechanism to move a moving block in the Z direction, and a holding head is attached to a shaft driven in the Z direction by the voice coil motor. An electronic component mounting apparatus is disclosed. Further, in Patent Document 2, the applied pressure is estimated from the current applied to the voice coil motor without using a load sensor such as a load cell.

  In Patent Document 3, the pressure at the time of joining is detected by load sensors provided at a plurality of locations on the holding head side, and the inclination of the lower surface of the holding head is adjusted so that the pressure value becomes uniform, whereby an electronic component and a substrate An electronic component mounting apparatus having a parallel surface is disclosed.

Patent Document 4 discloses a bonding apparatus that presses and joins a tape substrate to an electronic component placed on a table with bumps facing upward, using strain gauges provided at a plurality of positions of a bonding tool that holds the tape substrate. An electronic component mounting apparatus is disclosed that adjusts the inclination of the table so that the pressure surface of the bonding tool and the bonding surface of the electronic component are parallel to each other based on the detected applied pressure. Patent Document 5 discloses an electronic component mounting apparatus that adjusts the tilt of a stage based on outputs of load sensors provided at a plurality of locations on a table. Further, Patent Document 5 discloses a technique for matching the pressing force of the bonding tool with the pressurizing pattern by performing feedback control based on the output of another load sensor provided in the bonding tool.
JP-A-10-163273 (FIG. 1, paragraph 0017) JP-A-8-203966 (FIG. 1, paragraph 0025) Japanese Patent Laid-Open No. 11-297664 Japanese Patent Laid-Open No. 4-94553 JP-A-4-223349

  By the way, in the conventional electronic component mounting apparatus 100 shown in FIG. 1, the load cell 130 is located between the first moving block 110 and the second moving block 120, and is closer to the (−Z) side (lower side) than the load cell 130. A slider 111 and a guide rail 112 are provided. When the slider 111 slides on the guide rail 112, it is inevitable that a certain amount of sliding resistance (for example, about 30 g weight) is generated, and the load detected by the load cell 130 includes an error due to this sliding resistance. It is. Therefore, when the drive of the motor 150 is controlled based on the load detected by the load cell 130, the load applied to the electronic component 101 varies. If the load actually applied to the electronic component 101 is too small than the required load, sufficient strength for joining the electronic component 101 and the substrate 102 cannot be obtained, and contact failure or the like may occur. On the other hand, if the load actually applied to the electronic component 101 is too larger than the required load, the bump 101a at the bottom of the electronic component 101 may be crushed or the electronic component 101 itself may be damaged.

  Further, when the electronic component 101 is inclined with respect to the surface of the substrate 102, a load is not uniformly applied to each bump 101a at the bottom of the electronic component 101, and a contact failure occurs for some bumps, The bumps may be crushed.

  In order to reduce the sliding resistance when the moving block moves in the Z direction, for example, an air bearing may be used. However, when the load applied to the electronic component is small (for example, about 300 g weight), it can be supported by the air bearing, but when a load exceeding a certain limit is applied, the air bearing cannot be used. Such a problem also applies to the electronic component mounting apparatus disclosed in Patent Document 1.

  In the electronic component mounting apparatus of Patent Document 2, since the holding head is attached to the shaft driven in the Z direction by the voice coil motor and moved, the sliding resistance is generated as in the case of FIG. In addition, since the load applied to the electronic component is indirectly measured, as described above, there is a possibility of poor contact between the electronic component and the substrate, collapse of the bump, or damage to the electronic component itself.

  Similarly, in the electronic component mounting apparatuses of Patent Document 3 to Patent Document 5, since the load applied to the electronic component is indirectly measured through a mechanism such as tilt adjustment, the load actually applied to the electronic component is determined. It is difficult to measure accurately. For this reason, it is difficult to accurately adjust the inclination of the electronic component with respect to the substrate surface, which is performed based on the output from the load sensor, and there is a limit to the prevention of abnormal mounting of the electronic component due to improved accuracy. Further, in order to improve the load measurement accuracy, it is necessary to dispose the load sensors at a plurality of locations in the apparatus, and it is difficult to detect the load in the vicinity of the mounting position.

  The present invention has been made to solve the above-described problems of the conventional example, eliminates the influence of errors caused by sliding resistance when the moving block moves, and accurately applies the load actually applied to the electronic component. It is an object of the present invention to provide an electronic component mounting apparatus that can be measured.

The invention described in claim 1 is an electronic component mounting apparatus for mounting an electronic component on a board, and includes a moving block driven in the mounting direction of the electronic component and a highly rigid integrated block for holding the electronic component. A holding head; a load sensor that is provided between the moving block and the holding head and supports the holding head; a guide mechanism that guides the moving block to be movable in the mounting direction; and A drive mechanism for driving in the mounting direction; a storage unit for preliminarily storing a load profile indicating a change in load value in a direction parallel to the mounting direction to be applied to the electronic component when the electronic component is mounted; A control unit that controls driving of the moving block according to a load profile, and a vertical load in a direction parallel to the mounting direction detected by the load sensor By comparing the value and said load profile, comprising a mounting abnormality detecting unit for detecting the mounting abnormality of the electronic components, a displacement sensor for detecting a displacement amount in a direction parallel to the mounting direction of the retaining head, the mounting abnormality The detection unit detects the mounting abnormality of the electronic component by comparing the displacement amount of the holding head from the mounting start to the end detected by the displacement sensor with a reference displacement amount stored in the storage unit in advance. you.

A second aspect of the present invention is the electronic component mounting apparatus according to the first aspect, wherein the load sensor includes a vertical load in a direction parallel to the mounting direction, and a perpendicular to the mounting direction and 2 perpendicular to each other. to have the three piezoelectric elements for generating a voltage by receiving the horizontal load in the direction.

A third aspect of the present invention is the electronic component mounting apparatus according to the second aspect, wherein the mounting abnormality detection unit uses a value of the horizontal load in the two directions detected by the load sensor as a coordinate value. An electronic component mounting abnormality is detected by comparing a position in the two-dimensional space with an allowable range in the two-dimensional space stored in advance in the storage unit .

According to the present invention, since the load applied to the electronic component is measured by the load sensor provided between the moving block and the holding head, it is affected by the sliding resistance by the guide mechanism for guiding the moving block. Therefore, the load applied to the electronic component when the electronic component is mounted can be measured with higher accuracy .

  The present invention relates to an electronic component mounting apparatus capable of accurately measuring a load applied to an electronic component by providing a load sensor in the vicinity of a holding head to eliminate the influence of sliding resistance of a guide mechanism. Hereinafter, an electronic component mounting apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a diagram showing a configuration of an electronic component mounting apparatus 10 according to an embodiment of the present invention. The electronic component mounting apparatus 10 includes a substrate 2 on which circuit wiring is formed on an electronic component 1 that is a semiconductor bare chip. Install on top.

  In the electronic component mounting apparatus 10, a nut portion 21 provided on the moving block 20 that moves in the Z direction is engaged with a feed screw 51 that is rotationally driven by a motor 50. A slider 11 is provided on a side surface of the moving block 20 and slides on the guide rail 12 facing the Z direction. The slider 11 and the guide rail 12 serve as a guide mechanism for guiding the moving block 20 to be movable in the mounting direction of the electronic component 1. Further, the motor 50, the feed screw 52 and the nut portion 21 of the moving block 20 constitute a drive mechanism for driving the moving block 20 in the mounting direction of the electronic component 1.

  At the lower end of the moving block 20, a shaft 13 whose central axis is arranged in the Z direction, a load sensor 30 having a piezoelectric element for measuring a load applied to the electronic component 1, and an ultrasonic transducer 14 are attached. The block 141 and the holding part 15 for sucking and holding the electronic component 1 by negative pressure are sequentially provided. The holding part 15, the block 141, and the members between the holding part 15 and the block 141 are assembled as a holding head 15 a that is an integrated block having high rigidity. A pipe 16 connected to a vacuum pump (not shown) is connected to the holding unit 15, and the electronic component 1 is adsorbed by performing suction from a suction port formed on the lower surface of the holding unit 15. On the (+ X) side of the shaft 13, an optical (optical interference type) linear scale 70 is provided that is a displacement sensor that detects a displacement amount of the holding head 15 a in the Z direction (the mounting direction of the electronic component 1). The outputs of the linear scale 70 and the load sensor 30 are input to the control unit 60.

  A table 40 movable in the X direction and the Y direction is provided below the holding head 15a, and the substrate 2 is placed and held on the table 40. A mechanism for supplying the electronic component 1 and a camera for detecting the relative positions of the electronic component 1 and the substrate 2 are not shown.

  The attachment structure of the load sensor 30 and the holding head 15a is shown in FIG. The block 141 to which the ultrasonic transducer 14 is attached and the load sensor 30 are provided with through holes 14 a and 30 a through which the bolts 35 pass, and the load sensor 30 is interposed between the block 141 and the shaft 13 of the moving block 20. The block 141 and the load sensor 30 are attached to the shaft 13 with bolts 35 so as to sandwich the shaft. That is, the holding head 15a is attached so as to be substantially supported only by the load sensor 30. Moreover, the holding | maintenance part 15 is attached to the block 141 with the volt | bolt which is not illustrated.

  In the load sensor 30, three plate-like piezoelectric elements 31, 32 and 33 are stacked in the Z direction (the mounting direction of the electronic component 1). For example, the uppermost piezoelectric element 31 is mounted on the electronic component 1. The load in the direction substantially parallel to the direction (the Z direction shown in FIG. 2 and does not necessarily coincide with the direction of gravity) (the load in the direction perpendicular to the substrate 2). The polarization direction of the piezoelectric element is determined so that a voltage is generated in response. Similarly, the piezoelectric elements 32 and 33 in the intermediate layer and the lowermost layer are respectively loaded in two directions (X direction and Y direction) substantially perpendicular to the mounting direction of the electronic component 1 and substantially perpendicular to each other (hereinafter referred to as “horizontal load”). The polarization direction of the piezoelectric element is determined so as to generate a voltage in response to the above.

  The load sensor 30 has an attachment surface 30b to which the holding head 15a is directly attached, and another attachment surface 30c that is parallel to the attachment surface 30b and attached to the shaft 13 of the moving block 20. Thus, it is possible to easily attach and detach the load sensor 30 to and from the shaft 13 with a single bolt 35 in a constant posture.

  FIG. 4 is a diagram illustrating an operation flow of the electronic component mounting apparatus 10 when the electronic component 1 is mounted on the substrate 2. When mounting the electronic component 1 on the substrate 2, first, the substrate 2 is placed and held on the table 40 (step S11), and the holding unit 15 receives the electronic component 1 from the supply mechanism and performs vacuum suction. Hold (step S12). Subsequently, the electronic component 1 moves above the mounting position on the substrate 2, and the alignment of the relative position between the electronic component 1 held by the holding unit 15 and the substrate 2 is performed (step S13).

  Next, the motor 50 is rotationally driven in a predetermined direction, and the holding unit 15 is lowered in the (−Z) direction together with the moving block 20 (step S14), and the electronic component 1 comes into contact with the substrate 2. The contact between the electronic component 1 and the substrate 2 is accurately detected based on the output of the load sensor 30 by the contact detection unit 61 of the control unit 60 shown in FIG. 2 (step S15). When the required accuracy of contact detection between the electronic component 1 and the substrate 2 is not relatively high, the displacement amount in the Z direction (mounting direction) of the electronic component 1 detected by the linear scale 70 and the motor 50 are supplied. The contact may be detected from the relationship with the current (motor torque). Further, it may be considered that the electronic head 1 and the substrate 2 are in contact with each other when the holding head 15a is lowered by a predetermined distance based on the output from the encoder of the motor 50.

  FIG. 5 is a diagram showing a load profile 601 showing a change with time of a vertical load to be applied to the electronic component 1 at the time of mounting, and the load profile 601 is stored in advance in the storage unit 62 of the control unit 60. In the load profile 601 shown in FIG. 5, the load gradually increases from the start of mounting to time t1, pressurization with a constant load is performed for a predetermined time from time t1, and further, the load increases until time t2. Indicates that pressurization with a constant load is performed for a predetermined time. It should be noted that the shape of the load profile 601 is variously changed according to the type of electronic component 1 or substrate 2, the mounting method, and the like.

  When contact between the electronic component 1 and the substrate 2 is detected in step S15, the driving of the moving block 20 is controlled by the control unit 60 according to the load profile 601, and pressurization to the electronic component 1 is started (step S16). Then, in a state where the load detected by the load sensor 30 is gradually increased and the electronic component 1 is pressurized with a predetermined load, the ultrasonic transducer 14 is activated by a signal from the control unit 60 and the electronic component is activated. 1 is applied with ultrasonic waves, the bumps 1a provided on the bottom of the electronic component 1 are coupled to the wiring pattern on the substrate 2, and mounting is performed simultaneously with the mounting (step S17).

  Thereafter, blow is performed from the holding unit 15 via the pipe 16 and a valve (not shown) provided in the pipe 16 is opened, and the holding unit 15 is separated from the electronic component 1. Then, the motor 50 is rotationally driven in the reverse direction to raise the moving block 20 (and the holding head 15a) in the (+ Z) direction, thereby completing the mounting of the electronic component 1 (step S18).

  In the electronic component mounting apparatus 10, when any abnormality occurs in the load applied to the electronic component 1 or the displacement of the electronic component 1 when the electronic component 1 is mounted on the substrate 2 (steps S 16 and S 17), the load sensor 30. Based on the output from the linear scale 70, the controller 60 detects an abnormal mounting of the electronic component 1. FIG. 6 is a diagram illustrating a flow of an operation for detecting an abnormal mounting of the electronic component 1 in the electronic component mounting apparatus 10. Hereinafter, the abnormality detection operation performed in parallel with the mounting process of the electronic component 1 will be described with reference to FIG. 6 and other drawings.

  First, when contact between the electronic component 1 and the substrate 2 is detected and pressurization to the electronic component 1 is started, a load applied to the electronic component 1 is detected by the load sensor 30 and sent to the control unit 60 ( In step S21), the vertical load detected by the piezoelectric element 31 is compared with the load profile 601 stored in the storage unit 62, and the allowable range of the load profile 601 shown in FIG. 5 (lines positioned above and below the load profile 601). It is confirmed whether or not it is within the range 602 (range between 6021) (step S22). Simultaneously with the contact detection between the electronic component 1 and the substrate 2, the measurement of the displacement amount of the holding head 15a by the linear scale 70 is also started.

  When the mounting abnormality detection unit 63 (see FIG. 2) of the control unit 60 determines that the vertical load is outside the allowable range 602 of the load profile 601, the warning lamp 64 provided in the electronic component mounting apparatus 10 is turned on. Thus, the detection of the abnormal mounting of the electronic component 1 is notified to the worker (step S30). For example, when a sliding abnormality or the like of the slider 11 or the guide rail 12 occurs, the detected vertical load may be a small value outside the allowable range 602 of the load profile 601. In this case, a bonding failure between the bump 1 a and the substrate 2 may occur due to insufficient press of the electronic component 1 against the substrate 2, and such a mounting abnormality is detected by the mounting abnormality detection unit 63.

  If it is determined that the vertical load is within the allowable range 602 of the load profile 601, then the horizontal load detected by the piezoelectric elements 32 and 33 is the horizontal load allowable range stored in advance in the storage unit 62. To be compared. FIG. 7 is a diagram showing a horizontal load allowable range 603 applied to the electronic component 1 on a two-dimensional space 604 in which the loads in the X direction and the Y direction are the X axis and the Y axis, respectively. The allowable range 603 is an area of a circle or an ellipse (which may be other shapes according to the shape of the electronic component 1 or the like) centered on the origin of the two-dimensional space 604 surrounded by the line 6031. Based on the load profile 601, the image is enlarged or reduced about the origin. A solid line 6031 in FIG. 7 indicates the allowable range 603 of the load profile 601 shown in FIG. 5 at time t1, and pressurization of the electronic component 1 proceeds and the pressurization state is time t2 of the load profile 601. In this state, it is enlarged to the position indicated by the two-dot chain line based on the value of the vertical load indicated by the load profile 601 at time t2.

  In the mounting abnormality detection unit 63 of the control unit 60, the position having the horizontal load values in the X direction and the Y direction detected by the load sensor 30 as coordinate values is compared with the allowable range 603 (step S 23), and outside the allowable range 603. In such a case, the warning lamp 64 is turned on to notify the operator of the detection of abnormal mounting of the electronic component 1 (step S30). As a case where a mounting abnormality is detected in step S23, for example, when the electronic component 1 is held tilted with respect to the substrate 2 due to a suction error by the holding unit 15 or a foreign object biting, or some bumps A case where a foreign matter is caught between 1a and the substrate 2 can be considered.

  8-10 is a figure which shows the vicinity of the electronic component 1 hold | maintained at the holding | maintenance part 15. FIG. As shown in FIG. 8 to FIG. 10, a foreign object is formed between the electronic component 1 and the holding unit 15 or the substrate 2 or between the substrate 2 and the table 40 on the (+ X) side when viewed from the center of the electronic component 1. When the biting of 80 occurs, the bump (1) on the (+ X) side of the electronic component 1 comes before the bump (1) on the (−X) side (in the case shown in FIG. ) The substrate 2 is brought into contact, and pressurization to the electronic component 1 is started from this state. At this time, when the load is concentrated on the (+ X) side bump 1a, the position of the horizontal load detected by the load sensor 30 in the two-dimensional space 604 is shifted from the origin to the (+ X) side and outside the allowable range 603. Become. In this case, a load is not uniformly applied to each bump 1a at the bottom of the electronic component 1, and the (+ X) side bump 1a is crushed due to load concentration, or between the (−X) side bump 1a and the substrate 2. There is a possibility that the bonding failure may occur or the electronic component 1 itself may be damaged due to non-uniform pressurization. The mounting abnormality detection unit 63 detects a mounting abnormality caused by such a horizontal load deviation. .

  In the electronic component mounting apparatus 10, the allowable range 603 is also obtained when the position in the space 604 indicating the horizontal load applied to the electronic component 1 due to the biting of the foreign object 80 is not only in the (+ X) direction but also in other directions. Thus, the mounting abnormality detection unit 63 detects the mounting abnormality.

  When the mounting abnormality detection unit 63 determines that the horizontal load is within the allowable range 603, the control unit 60 confirms whether or not the mounting of the electronic component 1 is finished (step S24). Returning to step S21, the measurement of the load and the detection of the mounting abnormality (steps S21 to S23) are repeated until the mounting of the electronic component 1 (pressure application to the electronic component 1 performed according to the load profile 601) is completed (step S24). .

  When the mounting of the electronic component 1 is completed, the amount of displacement of the holding head 15a from the start of mounting the electronic component 1 (when contact between the electronic component 1 and the substrate 2 is detected) to the end (end of pressurization of the electronic component 1) is linear. It is detected by the scale 70 and sent to the control unit 60 (step S25), and is compared with a reference displacement amount (hereinafter referred to as “reference displacement amount”) stored in advance in the storage unit 62 (step S26). .

  When the detected displacement amount is outside the allowable range previously related to the reference displacement amount, the mounting abnormality detecting unit 63 turns on the warning lamp 64 to detect the mounting abnormality of the electronic component 1. The operator is notified and the mounting abnormality detection operation ends (step S30). For example, when the electronic component 1 is unnecessarily close to the substrate 2 due to the bump 1a of the electronic component 1 being tilted at the time of mounting, the detected displacement takes a large value outside the allowable range, and such mounting is performed. An abnormality is detected by the mounting abnormality detection unit 63.

  Further, when the displacement detected by the linear scale 70 is within the allowable range of the reference displacement, it is determined that the mounting (and mounting) of the electronic component 1 on the board 2 has been completed normally, and a mounting abnormality is detected. The operation ends. As described above, in the electronic component mounting apparatus 10, the detection result of the load sensor 30 and the linear scale 70 is compared with the allowable range stored in advance in the storage unit 62, so that the mounting abnormality of the electronic component 1 is mounted. Detected by the abnormality detector 63. Note that in the electronic component mounting apparatus 10, even when a mounting abnormality is detected in steps S22 and S23, if the degree of mounting abnormality is slight, the mounting operation of the electronic component 1 is continued, and a series of operations are performed. Until the mounting operation is completed, detection of load and displacement by the load sensor 30 and the linear scale 70 is continued, and measurement results in each step (steps S22, S23, S26) for detecting mounting abnormality are acquired.

  FIG. 11 is a diagram illustrating another example of the mounting structure of the load sensor 30 and the holding head 15a. In FIG. 11, a heat block 142 having a heater is attached instead of the block 141 as compared with the structure shown in FIG. 3, and the semiconductor bare chip, which is an IC, is held by the holding unit 15 as the electronic component 1. The holding head 15a is assembled by the holding unit 15 and the heat block 142 as an integrated block having high rigidity. Other configurations are the same as those in FIG. 3, and are denoted by the same reference numerals. The structure and attachment method of the load sensor 30 are also the same as in FIG. 3, and the load sensor 30 and the heat block 142 can be easily attached to and detached from the shaft 13 by bolts 35. A linear scale 70 that measures the displacement of the holding head 15 a in the Z direction is provided on the (+ X) side of the shaft 13.

  When the electronic component 1 is mounted, a thermosetting anisotropic conductive resin film (ACF (ACF)) (hereinafter referred to as “ACF”) 2a is pasted on the substrate 2 in advance. The holding unit 15 is preheated by the heat block 142. Therefore, when the electronic component 1 is held by the holding unit 15, the electronic component 1 is heated via the holding unit 15. When the holding unit 15 is lowered, the electronic component 1 is pressed onto the substrate 2 via the ACF 2a, and the conductive fine particles in the ACF 2a are crushed, so that the electrode 1b of the electronic component 1 and the electrode on the substrate 2 are Electrically joined. Simultaneously with the bonding, the ACF 2 a is heated and cured through the electronic component 1, and the electronic component 1 is fixed to the substrate 2. When the joining is completed, the holding portion 15 is lifted by releasing the suction.

  Next, materials suitable for the piezoelectric element for the load sensor 30 will be described. Table 1 shows the relationship between the material of the piezoelectric element and various constants.

For example, in the case of quartz, the dielectric constant and piezoelectric strain constant are low and the sensitivity is low, but the Curie point is high and the stability is excellent. Therefore, when bonding is performed using a heater as in the case shown in FIG. 11 and measurement accuracy is required, it is preferable to use crystal. On the other hand, in the case of piezoelectric ceramics such as zircon / lead titanate (Pb (TiZr) O ₃ ), although the Curie point is lower than that of quartz, the dielectric constant, the piezoelectric strain constant, etc. are high and the response is excellent. Moreover, it has the characteristics that it is easy to process into an arbitrary shape and is excellent in mass productivity. From the above, according to the accuracy, responsiveness, cost, etc. required for the load sensor 30, an optimal one is appropriately selected from quartz and piezoelectric ceramics.

  As described above, in the electronic component mounting apparatus 10, the load sensor 30 is directly attached to the holding head 15 a which is a highly rigid integral block, and therefore the load value detected by the load sensor 30 is applied to the electronic component 1. It can be considered equivalent to the applied load. In particular, in the Z direction, which is the mounting direction of the electronic component 1, the load sensor 30 is disposed closer to the holding head 15 a than the sliding portion of the slider 11 and the guide rail 12. The value is not affected by the sliding resistance between the slider 11 and the guide rail 12. Therefore, compared with the conventional electronic component mounting apparatus, a measurement value closer to the actual load applied to the electronic component 1 can be obtained, and the measured value is added to the electronic component 1 when the electronic component 1 is mounted. The load can be measured with higher accuracy.

  Further, by detecting the horizontal load using the piezoelectric elements 32 and 33 provided in the mounting direction of the electronic component 1, the piezoelectric element 31 provided in the piezoelectric elements 32 and 33 is further used. By detecting the vertical load, the size of the load sensor 30 in the horizontal direction can be reduced, and the load in the three directions applied to the electronic component 1 can be detected in the vicinity of the mounting position of the electronic component 1. As a result, the load applied to the electronic component 1 can be measured with higher accuracy.

  In the electronic component mounting apparatus 10, by comparing the vertical load applied to the electronic component 1 with the load profile 601, the deviation of the horizontal load applied to the electronic component 1 and the amount of displacement of the electronic component 1 at the time of mounting are determined. By detecting the abnormality, it is possible to accurately detect the mounting abnormality when the electronic component 1 is mounted. Then, by removing the substrate 2 in which the mounting abnormality is detected as a defective product from the mass production process, it is possible to prevent the electronic device as a finished product from being defective.

  In the electronic component mounting apparatus 10, the motor 50 that drives the holding head 15 a and presses the electronic component 1 against the substrate 2 based on the comparison result between the measured value of the vertical load detected by the load sensor 30 and the load profile 601. Feedback control may be performed by the control unit 60. As described above, since the electronic component mounting apparatus 10 can accurately measure the vertical load applied to the electronic component 1, the motor 50 can be controlled with high accuracy. It is also possible to make the vertical load variation less than several grams. As a result, it is possible to prevent bonding failure between the electronic component 1 and the substrate 2, damage to the bumps 1a and electrodes 1b at the bottom of the electronic component 1, or damage to the electronic component 1 itself.

  In the electronic component mounting apparatus 10, the allowable range 603 in which the position having the horizontal load values in the X direction and the Y direction as coordinate values in the two-dimensional space 604 is a circle or an ellipse centered on the origin of the two-dimensional space 604. Compared with That is, since the allowable range 603 is defined for the combined vector of the load vector in the X direction and the Y direction, it is possible to detect the mounting abnormality by comprehensively considering the load deviation in the X direction and the Y direction. it can. Further, by setting the allowable range 603 to be an ellipse, the major axis and minor axis of the ellipse can be set corresponding to the shape of the electronic component 1 or the sensitivity difference between the piezoelectric element 32 in the X direction and the piezoelectric element 33 in the Y direction. The allowable range 603 can be set appropriately.

  A load sensor using a piezoelectric element has a wider range of load measurement than a load cell using a strain gauge. Further, both quartz and piezoelectric ceramics, which are materials of the piezoelectric element, have higher rigidity and smaller deformation than the metal elastic body constituting the load cell, so there is almost no hysteresis of elastic deformation. For this reason, the load applied to the electronic component 1 can be measured with higher accuracy. Furthermore, since the load sensor using the piezoelectric element has a faster response speed than the case of using the load cell, the contact between the electronic component 1 and the substrate 2 can be detected with higher accuracy, and the electronic component can be detected at high speed. Even when mounting is performed, the load applied to the electronic component 1 can be accurately measured. Therefore, by using the piezoelectric elements 31 to 33 as the load sensor 30, the electronic component mounting apparatus 10 with higher versatility can be realized.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible.

  For example, a ball spline may be used as a mechanism for guiding the movement of the moving block 20. In this case, the orientation of the electronic component may be changeable by rotating the entire ball spline around the central axis.

  Moreover, in the said embodiment, although the piezoelectric element was used as a load sensor, depending on the magnitude | size of a load and load detection accuracy, a load cell may be used similarly to the past. Even in such a case, the load detected by the load sensor does not include error components due to the sliding resistance of the guide mechanism, etc., so a measurement value close to the actual load actually applied to the electronic component can be obtained. The load to be applied to the electronic component when the electronic component is mounted can be controlled with higher accuracy.

  The electronic component mounting apparatus 10 can be used for various mounting of various electronic components. For example, an electronic component may be mounted (temporary bonding) on a solder bump on the substrate using the electronic component mounting apparatus 10, and the electronic component and the substrate may be bonded by melting and solidifying the solder by reflowing in the next step. . Alternatively, the electronic component mounting apparatus 10 may be used for the main pressure bonding in which the electronic component is temporarily pressure-bonded on the substrate to which the thermosetting resin film is attached, and pressure and heating are separately performed.

  The electronic component mounted by the electronic component mounting apparatus 10 is, for example, a semiconductor light emitting element such as an LED chip or a semiconductor laser, a packaged IC, a semiconductor such as a microchip such as a resistor or a capacitor, or a SAW (Surface Acoustic Wave: surface). An electronic component other than a semiconductor such as an elastic wave filter may be used, and the substrate may be formed of a material other than a resin such as glass or a semiconductor. Further, the electronic component at the time of mounting may be held by a mechanical chuck or an electrostatic chuck in addition to the suction by the negative pressure according to the above embodiment.

  The present invention is applicable to an electronic component mounting apparatus that mounts electronic components on a circuit board.

Front view showing a configuration of a conventional electronic component mounting apparatus The front view which shows the structure of the electronic component mounting apparatus which concerns on one embodiment of this invention Sectional view showing mounting structure of holding head and load sensor Diagram showing the flow of electronic component mounting operation Diagram showing load profile The figure which shows the flow of operation which detects mounting abnormality of electronic parts Diagram showing the allowable range of horizontal load applied to electronic components Diagram showing the vicinity of electronic components Diagram showing the vicinity of electronic components Diagram showing the vicinity of electronic components Sectional drawing which shows the other example of the attachment structure of a holding head and a load sensor

Explanation of symbols

1 Electronic component 2 Substrate 2a ACF
DESCRIPTION OF SYMBOLS 10 Electronic component mounting apparatus 11 Slider 12 Guide rail 13 Shaft 15 Holding part 15a Holding head 20 Moving block 21 Nut part 30 Load sensor 30b, 30c Mounting surface 31-33 Piezoelectric element 40 Table 50 Motor 51 Feed screw 60 Control part 62 Storage part 63 Mounting abnormality detection unit 70 Linear scale 80 Foreign object 601 Load profile 603 Allowable range S11 to S18, S21 to S26, S30 Step

Claims (3)

An electronic component mounting apparatus for mounting an electronic component on a substrate,
A moving block driven in the mounting direction of the electronic component;
A holding head that is an integral block having high rigidity for holding electronic components;
A load sensor provided between the moving block and the holding head and supporting the holding head;
A guide mechanism for guiding the moving block so as to be movable in the mounting direction;
A drive mechanism for driving the moving block in the mounting direction;
A storage unit that stores in advance a load profile indicating a change in load value in a direction parallel to the mounting direction to be applied to the electronic component when the electronic component is mounted;
A control unit for controlling driving of the moving block according to the load profile;
A mounting abnormality detection unit that detects a mounting abnormality of an electronic component by comparing a value of a vertical load in a direction parallel to the mounting direction detected by the load sensor and the load profile;
A displacement sensor for detecting a displacement amount of the holding head in a direction parallel to the mounting direction ;
The mounting abnormality detection unit compares the displacement amount of the holding head from the mounting start to the end detected by the displacement sensor with a reference displacement amount stored in advance in the storage unit, and mounts an electronic component. an electronic component mounting apparatus characterized that you detect the abnormality. The electronic component mounting apparatus according to claim 1,
The load sensor, characterized by chromatic three piezoelectric elements for generating a voltage by receiving vertical and and two orthogonal directions of the horizontal load to each other in the vertical load and the mounting direction in a direction parallel to the mounting direction Electronic component mounting device. The electronic component mounting apparatus according to claim 2 ,
The mounting abnormality detection unit has a position on the two-dimensional space in which the value of the horizontal load in the two directions detected by the load sensor is a coordinate value, and the two-dimensional space stored in the storage unit in advance. An electronic component mounting apparatus that detects an abnormal mounting of an electronic component by comparing with an allowable range.

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