JP5236223B2 - Die bonder and die bonding method - Google Patents

Description

  The present invention relates to a die bonder and a die bonding method for mounting a semiconductor chip (die) or the like on a lead frame or the like.

  When manufacturing a semiconductor device, die bonding for mounting a semiconductor chip (die) on a lead frame as a mounted member is performed. For this die bonding, a die bonder having a collet for adsorbing a chip is used (Patent Document 1).

  As shown in FIG. 8, such a die bonder includes a bonding arm (not shown) having a collet 3 for attracting the semiconductor chip 1 of the supply unit 2 and a confirmation camera (not shown) for observing the semiconductor chip 1 of the supply unit 2. And a confirmation camera (not shown) for observing the island portion 5 of the lead frame 4 at the bonding position.

  The supply unit 2 includes a semiconductor wafer, and the semiconductor wafer is divided into a large number of semiconductor chips 1. Further, the bonding arm holding the collet 3 can be moved between the pickup position and the bonding position via the conveying means.

  Further, the collet 3 is vacuum-sucked through the suction holes opened in the lower end surface thereof, and the chip 1 is adsorbed on the lower end surface of the collet 3. If this vacuum suction (evacuation) is released, the chip 1 is detached from the collet 3.

  Next, a die bonding method using this die bonder will be described. First, the chip 1 to be picked up is observed with a confirmation camera disposed above the supply unit 2, and the collet 3 is positioned above the chip 1 to be picked up, and then the collet 3 as indicated by an arrow A. Is lowered to pick up the chip 1. Thereafter, the collet 3 is raised as shown by the arrow B.

  Next, the island portion 5 of the lead frame 4 to be bonded is observed with a confirmation camera arranged above the bonding position, and the collet 3 is moved in the direction of arrow C, and above the island portion 5. After being positioned, the collet 3 is moved downward as indicated by an arrow D, and the chip 1 is supplied to the island portion 5. In addition, after the chip is supplied to the island portion 5, the collet 3 is raised as indicated by the arrow E and then returned to the standby position above the pip-up position as indicated by the arrow F.

  That is, by moving the collet 3 sequentially as indicated by arrows A, B, C, D, E, and F, the chip 1 positioned based on the observation of the pickup confirmation camera is picked up by the collet 3. The chip 1 is mounted on the island portion 5.

  However, the lead frame 4 side may be heated and a bonding operation may be performed. In such a case, the lead frame holding body 10 (see FIG. 9) holding the lead frame 4, the collet itself, the collet holding portion, and the like are thermally deformed by thermal expansion.

As described above, due to thermal deformation, there is a possibility that misalignment occurs between the collet 3 and the island portion 5 and an accurate bonding operation cannot be performed. Therefore, as shown in FIG. 10, the position of the tip of the collet 3 is measured by a non-contact type sensor 11, and the elongation of the collet itself due to thermal deformation is measured, or the collet as shown in FIG. It is possible to propose a method for measuring the height position of the collet 3 by bringing 3 into contact with the lead frame holder 10 or the lead frame.
JP 2006-73631 A

  If the direct elongation of the collet is measured by a non-contact type sensor, the positional relationship between the actual mounting position and the collet 3 is unknown, and the mounting cannot be performed accurately. In the contact type, the collet 3 needs to be brought into contact with a symmetrical object with certainty, and the collet needs to be controlled with high accuracy. For this reason, the work time is increased, and the detection accuracy is unstable and the reliability is inferior. Moreover, the contact type may be damaged (damaged) under high temperature and high speed environments.

  In view of the above problems, the present invention provides a die bonder and a die bonding method capable of performing highly accurate die bonding without being affected by thermal deformation.

The die bonder of the present invention is a die bonder having a collet that picks up and picks up a die at the pickup position and bonds at the bonding position, and is a part of the bonding object holding unit in the vicinity of the bonding target position of the bonding position, A reference part having the same position and thermal displacement, a detection means for detecting a three-dimensional offset amount of the collet with respect to the reference part, and a position correction corresponding to the offset amount detected by the detection means for the collet And when the displacement due to the temperature difference occurs between the reference part and the bonding target position, the correction for the displacement is added to the position correction.

  According to the die bonder of the present invention, the detection means can detect the three-dimensional offset amount of the collet with respect to the reference portion. The position correction for the offset amount can be performed on the collet by the control means. At this time, since the reference part is provided in a part of the bonding object holding part in the vicinity of the bonding target position, the thermal displacement at the reference part is the same as that of the bonding object holding part. For this reason, if the collet position correction based on the collet position at the reference part is performed, the positional relationship between the reference part and the bonding target position is known, so that no deviation occurs in the bonding by the collet.

  It is preferable to add a displacement amount due to a temperature difference between the reference portion and the bonding target position to the position correction. That is, if there is a temperature difference between the reference portion and the bonding target position, the collet offset amount at the reference portion and the collet offset amount at the bonding target position are different. For this reason, the offset amount of the collet at the bonding target position can be calculated by adding the thermal deformation amount difference based on the temperature difference to the offset amount of the collet at the reference portion.

  The detection means can be configured with a confirmation camera for observing the collet and the reference part in a non-contact state between the collet and the reference part. In this case, the confirmation camera is a lead to which the die is bonded. It can be configured by a recognition camera that recognizes the pocket portion of the frame.

  The detection of the collet offset amount by the detecting means may be performed in the path of the collet bonding operation. This prevents the collet from being moved out of the path of the bonding operation when detecting the offset amount of the collet.

The die bonding method of the present invention is a die bonding method in which a die is adsorbed and picked up by a collet at a pickup position, and the die adsorbed by the collet is bonded to an island portion of the lead frame at the bonding position. A collet is placed close to a reference part provided on the lead frame holding body and has the same thermal displacement as the island of the lead frame, and a three-dimensional offset amount of the collet with respect to the reference part is detected. When a displacement amount due to a temperature difference occurs between the correction and the island portion and the reference portion, this displacement amount is corrected for the collet .

  According to the die bonding method of the present invention, the collet is brought close to a reference portion provided on the lead frame holder of the lead frame, thereby detecting a three-dimensional offset amount of the collet with respect to the reference portion. Further, by performing position correction for the offset amount on the collet, it is possible to absorb the position shift of the island portion due to thermal deformation of the lead frame holder.

  The detection of the offset amount and the position correction for the offset amount may be performed for each batch or may be performed for each bonding. It is also possible to detect the offset amount and correct the position corresponding to the offset amount based on the previous position correction.

  In the present invention, it is possible to absorb (correct) the misalignment of the island portion due to thermal deformation of the lead frame holder on the collet side. For this reason, even if the lead frame is placed under heating, an accurate bonding operation can be performed without causing a shift in bonding by the collet.

  When there is a temperature difference between the reference part and the bonding target position, the collet offset amount at the bonding target position is calculated by adding the thermal deformation amount difference based on this temperature difference to the collet offset amount at the reference part. can do. As a result, a highly accurate bonding operation can be performed.

  By using a confirmation camera as the detection means, the offset amount of the collet can be accurately and stably detected at a site away from the collet. Further, since the collet and the reference part are not in contact with each other, the collet and the reference part are not damaged due to contact between the collet and the reference part, and the offset amount can be detected stably over a long period of time. In addition, the confirmation camera can be configured by a recognition camera that recognizes the pocket portion of the lead frame to which the die is bonded, thereby reducing the cost.

  By detecting the offset amount of the collet by the detection means in the path of the bonding operation of the collet, the collet is not moved out of the path of the bonding operation. For this reason, the existing mechanism can be used and cost reduction can be aimed at.

By performing the detection of the offset amount and the position correction for the offset amount for each batch, it is not necessary to adjust the position for each bonding, so that the work efficiency can be improved.
Further, by performing the detection of the offset amount and the position correction for the offset amount for each bonding, each bonding can be performed with high accuracy. Furthermore, if the detection of the offset amount and the position correction for the offset amount are performed based on the previous position correction, the offset amount can be reduced or eliminated, and workability can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 6 shows a die bonder, which performs die bonding for mounting a semiconductor chip (die) 21 on a lead frame 24.

  Such a die bonder includes a bonding arm 30 having a collet 23 that adsorbs the semiconductor chip (die) 21 of the supply unit 22, a confirmation camera 26 for observing the semiconductor chip 21 of the supply unit 22, and a lead frame 24 at the bonding position. And a confirmation camera 32 for observing the island portion 25.

  The supply unit 22 includes a semiconductor wafer 28 mounted and supported on a wafer support device 27. The semiconductor wafer 28 is divided into a large number of semiconductor chips 21. The collet 23 is connected to a collet holder 29, and the collet 23, the collet holder 29, and the like constitute a bonding arm 30. The bonding arm 30 can be moved between the pickup position and the bonding position via the conveying means 31. The transport unit 31 can drive the bonding arm 30 in the X, Y, θ, and Z directions.

  Further, the chip 21 is vacuum-sucked through the suction holes opened in the lower end surface of the collet 23, and the chip 21 is adsorbed on the lower end surface of the collet 23. If this vacuum suction (evacuation) is released, the chip 21 is detached from the collet 23.

  Next, a die bonding method using this die bonder will be described. First, the chip 21 to be picked up is observed with the confirmation camera 26 arranged above the supply unit 22, the collet 23 is positioned above the chip 21 to be picked up, and then the collet 23 is lowered. The lever chip 21 is picked up.

  Further, the confirmation camera 32 disposed above the bonding position observes the island portion 25 of the lead frame 24 to be bonded, moves the collet 23 onto the island portion 25, and then lowers the collet 23. Then, the chip 21 is supplied to the island portion 25.

  That is, the chip 21 confirmed based on the observation by the confirmation camera 26 is picked up by the collet 23 of the bonding arm 30, and the island portion 25 of the lead frame (substrate) 24 conveyed to the lower portion of the island portion recognition camera 32. Is recognized by the camera 32 and the position is measured. Then, feedback control is performed, the bonding arm 30 is driven, and the chip 21 is mounted on the island portion 25 at the measured position. For this reason, the collet 23 moves as indicated by an arrow A1 shown in FIG.

  Incidentally, the lead frame 24 is held by a lead frame holder 40 as shown in FIG. Further, the holding body 40 is heated by a heating means (for example, a heater), and the lead frame 24 is heated. For this reason, the position of the island part 25 of the lead frame 24 shifts due to thermal deformation of the holding body 40.

  Therefore, in the die bonder of the present invention, die bonding can be performed accurately without being affected by thermal deformation. Therefore, as shown in FIG. 1, the reference part 41 provided in a part of the bonding object holding part in the vicinity of the bonding target position of the bonding position, and the three-dimensional X, Y, Z direction of the collet 23 relative to the reference part 41 Detecting means 42 for detecting the offset amount, and control means 43 (see FIG. 2) for performing position correction on the collet 23 by the offset amount detected by the detecting means 42.

  The lead frame holding body 40 has a receiving portion (rail portion) 40a for receiving the lead frame 24 and a flange portion 40b provided on the receiving portion 40a, and a reference portion 41 is provided on the flange portion 40b. The reference part 41 is composed of, for example, a short cylindrical body 45. In other words, the thermal deformation of the lead frame holder 40 is the same as that of the reference portion 41, and the positional deviation of the reference portion 41 due to the thermal deformation corresponds to the positional deviation of the island portion 25 of the lead frame 24.

As shown in FIGS. 2 and 3, the detection means 42 is a confirmation camera (in this case, the confirmation camera 32) for observing the collet 23 and the reference portion 41 in a non-contact state between the collet 23 and the reference portion 41. And a reflecting means 46 and an illuminating means 47.

  The reflecting means 46 includes a first prism 48 and a second prism 49. The illumination means 47 includes a first illumination 50 and a second illumination 51. The first illumination 50 irradiates the first prism 48 with illumination light through the reference part 41 and the collet 23 whose front end surface 23a faces the reference part 41 in a close state. The second illumination 51 irradiates the second prism 49 with illumination light through the reference part 41 and the collet 23 whose front end surface 23a faces the reference part 41 in a close state. In this case, the illumination light of the first illumination 50 is irradiated along the Y-axis direction, and the second illumination 51 is irradiated along the X-axis direction orthogonal to the Y-axis.

  Illumination light from the first illumination 50 enters the confirmation camera 32 via the first prism 48 and the second prism 49, and illumination light from the second illumination passes through the second prism 49. Incident light. That is, by irradiating illumination light from the first illumination 50, the projection image (see FIG. 4) viewed from the Y direction of the reference portion 41 and the tip surface 23a of the collet 23 is reflected by the first prism 48, and then the second The light can be reflected by the prism 49 and incident on the confirmation camera 32. In addition, by irradiating illumination light from the second illumination 51, a projection image (see FIG. 5) of the reference portion 41 and the tip end surface 23a of the collet 23 seen from the X direction is reflected by the second prism 49, and a confirmation camera 32 can be incident.

  The control means 43 can be constituted by a microcomputer or the like, and a control means for controlling the transport means 31 for transporting the collet 23 can be used. In addition, you may comprise by the control means different from the control means which controls the conveyance means 31. FIG. In addition, this apparatus (die bonder) may be provided with a monitor that projects with the confirmation camera 32.

  Next, a position adjustment method using the die bonder configured as described above will be described with reference to a flowchart shown in FIG. First, by driving the conveying means 31, the collet 23 is made to face relative to the tip portion 23a close to the reference portion 41 as shown in FIG. 1 (step S1).

  Next, the process proceeds to step S2 to detect the offset amount. That is, by irradiating illumination light from the first illumination 50, the projection image of the reference portion 41 and the tip surface 23 a of the collet 23 viewed from the Y direction is incident on the confirmation camera 32 as described above. In this case, the second illumination 51 is turned off. Thereby, the offset amount with respect to the reference portion 41 of the collet 23 in the X direction and the Z direction shown in FIG. 4 is detected. Next, the illumination of the first illumination 50 is turned off, and the illumination light is irradiated from the second illumination 51 in that state, so that the reference portion 41 and the tip end surface 23a of the collet 23 viewed from the X direction as described above. The projected image is incident on the confirmation camera 32. Thereby, the offset amount with respect to the reference portion 41 of the collet 23 in the Y direction and the Z direction shown in FIG. 5 is detected.

  In this case, it is determined whether or not there is an offset in step S3. If there is no offset in the X, Y, and Z directions, the position of the collet 23 is not adjusted (position alignment), and the process proceeds to step S4 to start the bonding operation. If it is offset in step S3, the process proceeds to step S5 to correct the position of the collet 23.

  4 shows the projection image 55 of the reference portion 41 and the projection image 56 of the collet 23 viewed from the Y direction. In this case, the center line 58 of the projection image 56 is X with respect to the center line 57 of the projection image 55. The direction is offset by Δx. The lower end surface 56a of the projection image 56 of the collet 23 is offset from the upper end surface 60 of the projection image 55 of the reference portion 41 by Δzx with respect to the reference line 59 in the Z direction at a predetermined height position. In FIG. 4, with respect to the center line 57 of the projected image 55, the right side in the drawing is the + side and the left side is the-side. For this reason, in the example shown in the figure, the offset amount in the X direction is + Δx.

  5 shows a projected image 61 of the reference portion 41 and a projected image 62 of the collet 23 viewed from the X direction. In this case, the center line 64 of the projected image 62 is Y with respect to the center line 63 of the projected image 61. The direction is offset by -Δy. The lower end surface 62a of the projected image 62 of the collet 23 is offset from the upper end surface 60 of the projected image 61 of the reference portion 41 by Δzy with respect to the reference line 59 in the Z direction at a predetermined height position. In FIG. 5, the right side of the drawing with respect to the center line 63 of the projection image 61 is the + side, and the left side is the − side. For this reason, in the example shown in the figure, the offset amount in the Y direction is −Δy.

  Therefore, if there is an offset as in the states shown in FIGS. 4 and 5, data from the confirmation camera 32 is input to the control means 43, and the calculation processing unit of the control means 43 uses the offset. The quantities Δx, Δzx, Δy, Δzy are calculated. Position correction is performed on the collet 23 by the offset amounts Δx, Δzx, Δy, Δzy calculated in this way. That is, the position of the collet 23 is moved by the same dimension opposite to each offset direction (direction opposite to 180 °). Thereby, the position correction of the collet 23 is performed. In this embodiment, the X direction, the Y direction, and the Z direction are all offset, but only one or two directions may be offset. In such a case, the offset is offset. Position correction is performed only in the direction in which the image is being processed.

  If bonding is started in step S4 and this bonding is completed, the process proceeds to step S6 to determine whether the next bonding is started. If bonding is started, the process returns to step S1. If the bonding is finished in step S4, the operation is finished.

  In the determination in step S6, the detection of the offset amount and the position correction for the offset amount may be performed for each batch or may be performed for each bonding. Here, “per batch” means that the position is corrected before the bonding of the chip 23 to the island portion 25 of the lead frame 24 is started, so that all the island portions 25 of the lead frame 24 or a predetermined number of island portions 25 are obtained. This position correction is not performed until the bonding operation is completed. “Performed for each bonding” is to perform position correction before starting the bonding operation to each island portion 25.

  As described above, by correcting the position of the collet 23, the supply of the chip 23 to each island portion 25 can be performed stably and accurately.

  By the way, in the said embodiment, although there was no temperature difference in the reference | standard site | part 41 and a bonding object position, depending on the installation position of the reference | standard site | part 41, there may be a temperature difference. In such a case, the offset amount of the collet 23 at the reference portion 41 is different from the offset amount of the collet 23 at the bonding target position. For this reason, it is preferable to add the amount of thermal deformation based on this temperature difference to the offset amount of the collet 23 at the reference portion 41. That is, a temperature sensor capable of detecting the temperature between the reference portion 41 and the bonding target position is provided, and the difference in thermal deformation based on the temperature difference between the sensors is added to the offset amount of the collet 23 at the reference portion 41, thereby bonding. The offset amount of the collet 23 at the target position can be accurately calculated. In this case, since the coefficient of thermal expansion is known, such a calculation is possible.

  Further, even if the offset correction is detected and the position correction for the offset amount is performed on the collet 23 in the initial alignment state by canceling the previous position correction, the previous position correction is used as a reference. You may make it carry out. Here, performing the position correction up to the previous time as a reference means that the current offset amount is detected and the position correction corresponding to the offset amount is performed on the collet 23 subjected to the position correction.

  In the present invention, a three-dimensional offset amount in the X, Y, and Z directions with respect to the reference portion of the collet 23 is detected by bringing the collet 23 close to the reference portion 41 provided on the lead frame holder 40 of the lead frame 24. . Then, by performing position correction for the offset amount on the collet 23, it is possible to absorb the position shift of the island portion 25 due to thermal deformation of the lead frame holder 40. For this reason, even if the lead frame 24 is placed under heating, the bonding by the collet 23 is not shifted, and an accurate bonding operation can be performed.

  When there is a temperature difference between the reference portion 41 and the bonding target position, the amount of thermal deformation based on this temperature difference is added to the offset amount of the collet 23 at the reference portion 41, so that the collet 23 at the bonding target position is An offset amount can be calculated. As a result, a highly accurate bonding operation can be performed.

  By using the confirmation camera 32 as the detection means 42, the offset amount of the collet 23 can be detected accurately and stably at a site away from the collet 23. Further, since the collet 23 and the reference part 41 are not in contact with each other, the collet 23 and the reference part 41 are not damaged by the contact between the collet 23 and the reference part 41, and the offset amount can be detected stably over a long period of time. It becomes. In addition, the confirmation camera 32 can be configured by a recognition camera that recognizes the pocket portion 25 of the lead frame 24 to which the die 21 is bonded, and thus an existing die bonder can be used, thereby reducing costs. Can be planned.

  By performing the detection of the offset amount and the position correction for the offset amount for each batch, it is not necessary to adjust the position for each bonding, so that the work efficiency can be improved. Further, by performing the detection of the offset amount and the position correction for the offset amount for each bonding, each bonding can be performed with high accuracy. Furthermore, if the detection of the offset amount and the position correction corresponding to the offset amount are performed based on the previous position correction, the offset amount may be reduced or eliminated, thereby improving workability. it can.

  By the way, in the said embodiment, since the said reference | standard site | part 41 is arrange | positioned out of the path | route of bonding operation | movement, when detecting the offset amount of the collet 23, it was necessary to move the collet 23 out of the path | route of bonding operation | movement. . Therefore, the reference portion 41 may be arranged in the bonding operation path, and the detection of the offset amount of the collet 23 by the detecting means 42 may be performed in the collet bonding operation path.

  In this way, if the detection means 42 detects the offset amount of the collet 23 within the bonding operation path of the collet 23, the collet 23 is not moved out of the bonding operation path. For this reason, the existing die bonder can be used with almost the same control, and the cost can be reduced.

  As mentioned above, although it demonstrated per embodiment of this invention, this invention is not limited to the said embodiment, A various deformation | transformation is possible, for example, in the said embodiment, it is a short cylinder in the said embodiment as the reference | standard part 41. Although comprised, it is not restricted to a short cylinder, The thing of various shapes can be used. In short, if the collet 23 can be provided in a part that exhibits the same thermal displacement as the bonding object holding unit, and the collet 23 can approach the reference part 41, the offset amount in the triaxial direction of the collet 23 can be detected. Good. For this reason, the lead frame holder 40 itself may be used.

  Moreover, as the confirmation camera 32, in the above-described embodiment, the confirmation camera for the island unit 25 of the existing apparatus (die bonder) is used. However, another camera different from the confirmation camera for the island unit 25 is used. May be used. Furthermore, in the above-described embodiment, the offset amount of the three axes in the X, Y, and Z directions (three dimensions) is detected by one camera, but it may be detected by two or more cameras. . As the triaxial direction, the X and Y axes may not be orthogonal.

  As the detection means, a non-contact type detection sensor (for example, an optical sensor) that does not use the confirmation camera 32 can be used. Further, when detecting the offset amount of the collet 23, the offset amount of the collet 23 itself is detected in the above embodiment, but a part of the holding portion holding the collet 23 is brought close to the reference portion 41. The offset amount of the collet 23 may be detected based on a partial offset amount of the holding unit. In addition, as long as it can function as a detection sensor in the high-temperature atmosphere of this die bonder, a contact-type sensor can also be used.

It is a principal part simplified view of the die bonder which shows embodiment of this invention. It is a simplified side view of the die bonder. It is a simplified top view of the die bonder. It is a projection view from the Y direction of the collet of the die bonder and a reference part. It is a projection view from the X direction of the collet of the die bonder and a reference part. It is a whole perspective view of the die bonder. It is a flowchart figure of the die bonding method. It is explanatory drawing of the die bonding method. It is a simplified sectional view showing a measure against thermal deformation in a conventional die bonder. It is a simplified diagram showing another countermeasure against thermal deformation in a conventional die bonder.

Explanation of symbols

23 collet 24 lead frame 31 transport means 32 confirmation camera 41 reference part 42 detection means 43 control means

Claims (8)

In a die bonder with a collet that picks up and picks up a die at the pickup position and bonds at the bonding position.
A part of the bonding object holder in the bonding object position near the bonding position, and the reference site bonding object position and thermal displacement are the same,
Detecting means for detecting a three-dimensional offset amount of the collet with respect to the reference portion;
Control means for correcting the position corresponding to the offset amount detected by the detection means with respect to the collet, and if there is a displacement due to a temperature difference between the reference portion and the bonding target position, this displacement A die bonder characterized in that a correction for the amount is added to the position correction. 2. The die bonder according to claim 1, wherein the detecting means includes a confirmation camera for observing the collet and the reference part in a non-contact state between the collet and the reference part . The die bonder according to claim 2 , wherein the confirmation camera is a recognition camera that recognizes a pocket portion of a lead frame to which a die is bonded . The die bonder according to any one of claims 1 to 3, wherein the detecting means detects the offset amount of the collet within a path of the bonding operation of the collet . In the die bonding method of adsorbing and picking up the die with the collet at the pickup position and bonding the die adsorbed with the collet to the island part of the lead frame at the bonding position,
The collet is placed close to a reference part provided on the lead frame holding body of the lead frame and has the same thermal displacement as the island of the lead frame, and a three-dimensional offset amount of the collet with respect to the reference part is detected. A die bonding method characterized in that when a displacement due to a temperature difference occurs between the island portion and the reference portion, correction for the displacement is performed on the collet . 6. The die bonding method according to claim 5 , wherein the detection of the offset amount and the position correction for the offset amount are performed for each batch . 6. The die bonding method according to claim 5 , wherein the detection of the offset amount and the position correction for the offset amount are performed for each bonding. 8. The die bonding method according to claim 5 , wherein detection of the offset amount and position correction for the offset amount are performed based on the previous position correction .

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