JP4136733B2 - Pellet bonding method and pellet bonding apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pellet bonding method and a pellet bonding apparatus for bonding a pellet to a substrate such as a lead frame by pushing up a pellet such as a semiconductor chip attached to the adhesive sheet from the back surface of the adhesive sheet.
[0002]
[Prior art]
A large number of pellets adhered to the pressure-sensitive adhesive sheet are peeled off from the pressure-sensitive adhesive sheet using a pellet bonding apparatus and bonded to the island portion of the lead frame. In this process, at the time of peeling from the adhesive sheet, the suction nozzle of the bonding head provided in the pellet bonding apparatus adsorbs while pressing the pellet stuck to the adhesive sheet, and the push-up pin of the pellet push-up unit removes the pellet. Push up from the back of the adhesive sheet.
[0003]
Here, the suction nozzle is moved up and down by a linear motor which is a thrust generating device, and the thrust is determined by a current value applied to the linear motor. The downward thrust applied to the suction nozzle by the linear motor becomes the pressing force (hereinafter also referred to as “pickup load”) against the pellet pushed up by the push-up pin as it is. Conventionally, this pickup load has been controlled to be a constant value.
[0004]
Further, the push-up pin is raised at a constant speed, and a push-up load is applied to the pellets by the push-up operation by this rise.
[0005]
In other words, when the pellet attached to the adhesive sheet is peeled off, the pellet is subjected to a pick-up load by the suction nozzle and a push-up load by the push-up pin, and is sandwiched by both loads.
[0006]
[Problems to be solved by the invention]
By the way, even if the push-up pins are raised at the same speed for each pellet, the push-up force added to the pellets depends on the sticking force on the pressure-sensitive adhesive sheet of each pellet, the sticking state due to changes over time, etc. Is not necessarily constant. For example, if the sticking force is strong, a strong push-up load is applied as compared with weak ones.
[0007]
On the other hand, as described above, the pickup load is kept constant.
[0008]
For this reason, when the pellet is peeled, depending on the variation in the thrust load, the total value of the thrust load and the pickup load applied to the pellet will exceed the allowable value that will not damage the pellet, resulting in a large load on the pellet. In some cases, the pellets were damaged by cracking or chipping, and a good pellet bonding operation could not be performed.
[0009]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pellet bonding method and a bonding apparatus capable of preventing a damage to a pellet based on a variation in a push-up load applied to the pellet and performing a bonding operation with certainty.
[0010]
[Means for Solving the Problems]
The present invention adsorbs the pellets adhered to the pressure-sensitive adhesive sheet while pressing from the pellet side with an adsorption nozzle, and pushes it up from the back side of the pressure-sensitive adhesive sheet using a push-up pin to peel off the pellet. In a pellet bonding method for bonding to a substrate, the thrust load acting on the pellet is measured along with the thrusting operation of the thrust pin, and based on the measurement result, the suction nozzle acts on the pellet along with the pellet suction operation. The pressing force is controlled, and the pressing force is feedback-controlled so that the pinching force at which the pellet is pinched by the suction nozzle and the push-up pin is within an allowable range.
[0012]
The present invention adsorbs the pellets adhered to the pressure-sensitive adhesive sheet while pressing them from the pellet side with an adsorption nozzle, pushes them up from the back surface of the pressure-sensitive adhesive sheet using a push-up pin, peels off the pellets, and removes the pellets from the substrate. In the pellet bonding apparatus for bonding to the pellet, a load measuring means for measuring a thrust load acting on the pellet in accordance with a thrusting operation of the thrust pin, and a pressing force can be applied to the pellet via the suction nozzle to adjust the pressing force. Based on the measured value by the actuator and the load measuring means, the pressing force to the pellet by the actuator is such that the sandwiching pressure by which the pellet is sandwiched between the suction nozzle and the push-up pin is within an allowable range. to, to the control means for feedback control, comprising the .
[0013]
In addition, when the measured value by the said load measurement means exceeds an allowable range, it is preferable to have an output means for outputting an alarm signal.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a bonding head and a pellet push-up unit in a pellet bonding apparatus to which the present invention is applied. FIG. 2 is a flowchart showing the control of the controller of FIG. FIG. 3 is a schematic cross-sectional view for explaining the pellet pushing-up operation.
[0015]
The pellet bonding apparatus includes a pellet pushing unit 1 and a bonding head 2. The pellet pushing-up unit 1 peels a large number of pellets 11 stuck on the pressure-sensitive adhesive sheet 12 from the pressure-sensitive adhesive sheet 12. The bonding head 2 sucks and holds the peeled pellet 11 using the suction nozzle 13, transfers it to an island portion of a lead frame (not shown), and bonds it to the island portion.
[0016]
As shown in FIG. 1, the pellet pushing-up unit 1 includes a backup holder 14, a pin support 15 including a pin main support 16 and a pin sub-support 17, a cam 19 driven by a motor 18, and load measuring means. Load measuring element 20 and load measuring instrument 21, encoder 22 connected to the motor, load measuring instrument 21, motor 18, and controller 23 connected to the encoder 22 as control means. The
[0017]
A vacuum chamber 24 is formed in the backup holder 14. The pin holder 17 is inserted into the backup holder 14 through the vacuum chamber 24 so as to be slidable in the vertical direction in the figure. A vacuum pump hose (not shown) is connected to the vacuum chamber 24 via a passage 25. Further, a large number of small holes 26 are provided on the upper surface of the backup holder 14 so as to communicate with the vacuum chamber 24. Accordingly, the vacuum pump 24 operates to create a negative pressure in the vacuum chamber 24, and this negative pressure acts on the adhesive sheet 12 through the small holes 26, and the back surface of the adhesive sheet 12 is adsorbed on the upper surface of the backup holder 14.
[0018]
The pin support 15 is fitted to the upper portion 16A of the pin main support 16 so that the lower portion of the pin sub-support 17 is movable in the vertical direction in the figure, and a push-up pin 27 is provided on the upper end of the pin sub-support 17. Composed. The push-up pin 27 is formed so as to be able to pass through an insertion hole 28 formed on the upper surface of the backup holder 14. A load gauge 20 is installed between the lower part 16B of the pin main support 16 and the lower end of the pin sub support 17. A sliding contact roller 29 is rotatably supported on the lower portion 16B of the pin main support 16. The pin main support 16 is biased downward via a biasing means such as a spring 30 so that the sliding contact roller 29 is always in contact with the cam 19.
[0019]
Further, a long hole 31 is opened in the upper portion 16A of the pin main support body 16, and a locking pin 32 provided integrally with the lower portion of the pin sub support body 17 is locked in the long hole 31, and the pin main support body 16 and The pin sub-support 17 is integrated. The pin sub-support 17 is provided so as to be movable relative to the pin main support 16 in the vertical direction in the drawing within the range in which the locking pin 32 moves in the longitudinal dimension of the long hole 31. Supported by
[0020]
The motor 18 that drives the cam 19 is, for example, a stepping motor that can control the rotation angle and the rotation speed, can rotate forward and backward, and is controlled by the controller 23. The cam 19 is a plate cam having a cam surface having a constant velocity curve that raises the lift amount of the pin support 15 in proportion to the rotation angle. The encoder 22 connected to the motor 18 detects the rotation angle of the motor 18 that rotates the cam 19 and measures the lift amount (movement amount) of the pin support 15 and the push-up pin 27.
[0021]
The load measuring element 20 supports the load of the pin sub-supporting body 17, and the push-up force of the pin sub-supporting body 17 as the pin supporting body 15 rises by the action of the cam 19, that is, the push-up pin 27 acts on the pellet 11. The thrust load is measured at any time, and the measured value (more precisely, the value obtained by subtracting the load of the pin support 17 itself from the load applied to the load measuring element 20) is output to the controller 23 via the load measuring instrument 21.
[0022]
As shown in FIG. 1, the bonding head 2 has a suction nozzle 13 disposed above the pellet 11. The suction nozzle 13 is placed on the surface of the adhesive sheet 12 by a linear motor 33 capable of adjusting the thrust. It is supported so as to be movable in a vertical direction. The linear motor 33 includes a permanent magnet 35 fixed to a holder (not shown) and a coil 36 fixed to the suction nozzle side, and the thrust generated by the linear motor 33 can be controlled by a current controller 34. Control is performed so that the current value supplied to 36 is constant if the current value is constant, increases if the current value is large, and decreases if the current value is small.
[0023]
The controller 23 controls the generated thrust and the direction of the linear motor 33 through the current controller 34 based on the load measurement value input from the load measuring device 21, that is, the push-up load as described later, and controls the motor 18. Thus, the rotation angle and rotation speed of the cam 19 are controlled.
[0024]
Next, detailed control by the controller 23 will be described with reference to a flowchart shown in FIG. 2 and a schematic cross-sectional view for explaining the pellet pushing-up operation shown in FIG.
[0025]
First, various parameters are set in the controller 23 (S1). The parameters include, for example, the push-up speed v of the push-up pin 27, the maximum push-up amount s, the reference pickup load a, the reference push-up load b, and the upper limit allowable value c of the push-up load. Here, the value obtained by adding the reference push-up load b to the reference pickup load a, that is, the sandwiching pressure to the pellet 11 is determined from the thickness and size of the pellet 11 to be bonded this time, and damages the pellet 11. The value is within the range not given, and the value is obtained through experiments.
[0026]
Next, the linear motor 33 is driven, the suction nozzle 13 is moved downward, and the tip suction surface is brought into contact with the pellet upper surface (S2, FIG. 3A). At this time, the coil 36 of the linear motor 33 is supplied with a current for obtaining a thrust corresponding to the reference pickup load “a” to the suction nozzle 13, so that the suction nozzle 13 in contact with the pellet 11 And the reference pickup load a is applied to the pellet 13.
[0027]
Next, the push pin 27 is raised by driving the motor 18 (S3). Then, as the push-up pin 27 starts to rise, the push-up load applied to the pellet 11 by the push-up pin 27 is measured at any time by the load measuring element 20 and the load measuring device 21, and the measured value d is obtained (S4, FIG. 3 (b) )).
[0028]
Here, the obtained measured value d is compared with the upper limit value c of the thrust load (S5). If d> = c, it is determined that there is an abnormality, and the push-up pin 27 is lowered to stop the push-up operation (S6). Then, the next pellet 11 is pushed up (S12). On the other hand, when d <c, the measured value d is compared with the reference push-up load b (S7). If d> = b, (d−b) is calculated (S8). Next, ((a- (db)) is calculated and obtained, and the thrust by the linear motor 33 is corrected so that the pickup load by the suction nozzle 13 becomes this value (S9, FIG. 9 (c)). By this thrust correction, the pick-up load applied by the suction nozzle 13 to the pellet 11 is (a- (db)), while the push-up load becomes the measured value d. The total clamping pressure is (a + b), that is, the reference pickup load a and the reference push-up load b. As described above, the value obtained by adding the reference push-up load b to the reference pickup load a is Therefore, the range is determined to be within a range that does not damage the pellet 11, which is determined from the thickness and size of the pellet 11 to be bonded this time. Even upward thrust load d exceeds the reference value, the exceeded amount is fed back to a current value control to be applied to the linear motor 33, so that the pick-up load by the suction nozzle 13 is controlled to be reduced.
[0029]
Next, the push-up amount e of the push-up pin is detected based on the output value of the encoder 22 connected to the motor 18, and the detected value e is compared with the maximum push-up amount s (S10). When e> = s, the suction nozzle 13 ascends and holds the peeled pellet 11 and moves up to a lead frame (not shown) for bonding (S11, FIG. 3 (d)). . The push-up pin is also lowered to the origin position (S6), and the next pellet is pushed up (S12). On the other hand, if e <s, the process returns to S3.
[0030]
According to the above-described embodiment, when the pellet 11 adhered to the adhesive sheet 12 is adsorbed while being pressed by the adsorption nozzle 13 and is pushed up from the back side of the adhesive sheet using the push-up pin 27 and peeled off, the push-up pin 27 When the push-up load is measured and the measured value d exceeds the reference push-up load b, the suction nozzle 13 by the linear motor 33 is decreased so as to reduce the pressing force (pickup load) by the suction nozzle. The thrust of the engine was feedback controlled. As a result, even if the push-up load applied to the pellet 11 is fluctuated due to the rise of the push-up pin 27, the pressing force by the suction nozzle 13 is corrected, and the pellet 11 is pushed by the suction nozzle 13 and the push-up pin 27 when the pellet is peeled off. The applied clamping pressure is maintained at a load within a range that does not damage the pellet. Therefore, the pellet 11 can be prevented from being damaged due to the peeling of the pellet, and the substrate such as the lead frame can be prevented. On the other hand, it is possible to reliably perform the bonding operation.
[0031]
In the above-described embodiment, the measurement value of the load measuring means constituted by the load measuring element 20 and the load measuring instrument 21 is stored in, for example, a storage unit provided in the controller 23, and the information Can also be used as production management information. This is, for example, the maximum push-up load when the pellet 11 is peeled from the pressure-sensitive adhesive sheet 12 at the time of the peeling work involving the current push-up of the pellets, for all the pellets 11 for one pressure-sensitive adhesive sheet, Or a value obtained by calculating these values based on a predetermined formula is stored as reference push-up load or push-up load upper limit allowable value information in the combination of the pressure-sensitive adhesive sheet and the pellet. The next time, when the same type of adhesive sheet and pellet are combined, the previously stored information is recalled and used for the present peeling operation. By doing so, the reference push-up load or its upper limit allowable value can be set easily and quickly.
[0032]
In the above-described embodiment, the thrust load by the thrust pin 27 is measured by the load measuring means installed on the pellet thrusting unit 1 side. However, this load measuring means is measured on the bonding head 2 side having the suction nozzle 13. It may be provided.
[0033]
In the above-described embodiment, an example in which a linear motor is used as an actuator has been described. However, another actuator may be used as long as the actuator can adjust thrust.
[0034]
In the above-described embodiment, the present invention has been described as being applied to a pellet bonding apparatus. However, in a flip chip bonder or the like, the apparatus can be applied to a transfer apparatus that sucks a flip chip and delivers it to a collet of a bonding head. It is.
[0035]
【The invention's effect】
According to the present invention, even if the push-up load applied to the pellet varies, damage to the pellet can be prevented and a bonding operation can be performed reliably.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a bonding head and a pellet push-up unit in a pellet bonding apparatus to which the present invention is applied.
FIG. 2 is a flowchart showing control of the controller of FIG. 1;
FIG. 3 is a schematic cross-sectional view for explaining a pellet pushing-up operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pellet raising unit 2 Bonding head 11 Pellet 12 Adhesive sheet 13 Adsorption nozzle 14 Backup holder 15 Pin support body 16 Pin main support body 16A Upper part 16B Lower part 17 Pin sub support body 18 Motor 19 Cam 20 Load measuring element 21 Load measuring instrument 22 Encoder 23 Controller 24 Vacuum chamber 25 Passage 26 Small hole 27 Push-up pin 28 Insertion hole 29 Sliding roller 30 Spring 31 Long hole 32 Locking pin 33 Linear motor 34 Current controller 35 Permanent magnet 36 Coil

Claims (3)

The pellet stuck to the adhesive sheet is adsorbed while being pressed from the pellet side with an adsorption nozzle, and is pushed up from the back side of the adhesive sheet using a push-up pin, the pellet is peeled off, and the pellet is bonded to the substrate. In the pellet bonding method, a thrust load acting on the pellet along with the thrusting operation of the thrust pin is measured, and based on the measurement result, the suction nozzle acts on the pellet along with the pellet suction operation. controlling the pressing force, so that the clamping force which the pellets are clamped by a pin push-up and the suction nozzle is within the allowable range, the pellets bonding method characterized by the feedback control. Pellets adhered to the pressure-sensitive adhesive sheet are adsorbed while being pressed from the pellet side with an adsorption nozzle, pushed up from the back side of the pressure-sensitive adhesive sheet using a push-up pin, peeled off the pellet, and pellets for bonding the pellet to the substrate In the bonding apparatus, a load measuring means for measuring a thrust load acting on the pellet in accordance with a thrusting operation of the thrust pin, and an actuator capable of adjusting the pressing force by applying a pressing force to the pellet via the suction nozzle; Feedback control of the pressing force to the pellet by the actuator based on the measured value by the load measuring means so that the sandwiching pressure by which the pellet is sandwiched between the suction nozzle and the push-up pin is within an allowable range. pellets and control means for, comprising the Bindings apparatus. 3. The pellet bonding apparatus according to claim 2, further comprising an output unit that outputs an alarm signal when a value measured by the load measuring unit exceeds an allowable range.

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