JP2004273910A - Pellet bonding method and pellet bonding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage of a pellet caused by variations in a pushing-up load applied to the pellet and to realize reliable bonding operation. <P>SOLUTION: The pellet 11 adhered on an adhesive sheet 13 is pushed and sucked by a suction nozzle 13 from one side of the sheet provided with the pellet, released therefrom by pushing up the pellet from the rear side of the sheet using a pushing-up pin 27, and then bonded onto a substrate. A pushing-up load applied onto the pellet 11 through the pushing-up operation of the pin 27 is measured, and on the basis of the measured result, a pickup load applied to the pellet through the sucking operation of the pellet by the suction nozzle 13 is feedback controlled. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pellet bonding method and a pellet bonding apparatus in which a pellet such as a semiconductor chip stuck to an adhesive sheet is pushed up from a back surface of the adhesive sheet to bond the pellet to a substrate such as a lead frame.
[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 step, at the time of peeling from the pressure-sensitive adhesive sheet, the suction nozzle of the bonding head provided in the pellet bonding apparatus suctions and presses the pellet adhered to the pressure-sensitive adhesive sheet, and the push-up pin of the pellet push-up unit pushes 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 that is a thrust generator, 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 a pressing force (hereinafter, also referred to as “pickup load”) on the pellet pushed up by the push-up pin. Conventionally, the pickup load has been controlled to have a constant value.
[0004]
Further, the push-up pins are raised at a constant speed, and a push-up load is applied to the pellets by the push-up operation due to the lift.
[0005]
That is, when the pellets adhered to the pressure-sensitive adhesive sheet are peeled, the pellets are pressed by the pickup nozzle and the push-up load by the push-up pins, and are pressed by both loads.
[0006]
[Problems to be solved by the invention]
By the way, even if the push-up pin is raised at the same speed every time for each pellet, the push-up force applied to the pellet is determined by the sticking force of the pellet in the pressure-sensitive adhesive sheet, and the sticking state due to aging, etc. Is not always constant. For example, if the sticking force is strong, a strong thrust load is applied as compared with a weak sticking force.
[0007]
On the other hand, as described above, the pickup load was kept constant.
[0008]
For this reason, at the time of peeling the pellet, depending on the fluctuation of the pushing load, the total value of the pushing load and the pickup load applied to the pellet exceeds an allowable value that does not damage the pellet, and as a result, a large load is applied to the pellet. In some cases, the pellets are damaged due to cracking or chipping, and a good pellet bonding operation cannot be performed.
[0009]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a pellet bonding method and a bonding apparatus capable of preventing a pellet from being damaged due to a change in a thrust load applied to the pellet and performing a bonding operation reliably.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the pellet bonding method according to the present invention comprises: adhering the pellet adhered to the pressure-sensitive adhesive sheet while pressing the pellet from the pellet side by a suction nozzle; In a pellet bonding method of peeling the pellet and bonding the pellet to a substrate, a thrust load acting on the pellet is measured in accordance with a thrust operation of the thrust pin, and based on a measurement result, the suction nozzle is used to adjust the suction nozzle to It is characterized in that the pressing force acting on the pellets is controlled in accordance with the operation of adsorbing the pellets.
[0011]
In addition, it is preferable that the pressing force is feedback-controlled so that the narrow pressure in which the pellet is narrowed by the suction nozzle and the push-up pin is within an allowable range.
[0012]
Further, the invention according to claim 3 is that the pellet adhered to the pressure-sensitive adhesive sheet is sucked while being pressed from the pellet side by a suction nozzle, and is lifted up from the back surface of the pressure-sensitive adhesive sheet using a lifting pin to peel off the pellet. In a pellet bonding apparatus for bonding the pellet to a substrate, a load measuring means for measuring a pushing load acting on the pellet in accordance with a pushing operation of the pushing pin, and applying a pressing force to the pellet via the suction nozzle. An actuator capable of adjusting the pressing force, and control means for controlling the pressing force on the pellet by the actuator based on the value measured by the load measuring means are provided.
[0013]
In addition, it is preferable to have an output unit that outputs an alarm signal when the value measured by the load measurement unit exceeds an allowable range.
[0014]
BEST MODE FOR CARRYING OUT 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 illustrating the operation of pushing up a pellet.
[0015]
The pellet bonding apparatus includes a pellet push-up unit 1 and a bonding head 2. The pellet push-up unit 1 peels many pellets 11 stuck on the adhesive sheet 12 from the adhesive sheet 12. The bonding head 2 sucks and holds the exfoliated pellet 11 by using a suction nozzle 13, transports it to an island portion of a lead frame (not shown), and bonds it to this island portion.
[0016]
As shown in FIG. 1, the pellet push-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. , A load measuring element 20 and a load measuring device 21, an encoder 22 connected to a motor, and a controller 23 as control means connected to the load measuring device 21, the motor 18, and the encoder 22. You.
[0017]
A vacuum chamber 24 is formed in the backup holder 14. A pin sub support 17 is slidably inserted in the backup holder 14 through the vacuum chamber 24 in the vertical direction in the drawing. A hose of a vacuum pump (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 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 attracted to the upper surface of the backup holder 14.
[0018]
The pin support 15 has a lower portion of the pin sub-support 17 fitted to an upper portion 16A of the pin main support 16 so as to be movable in the vertical direction in the drawing, and a push-up pin 27 is provided at an upper end of the pin sub-support 17. Be composed. The push-up pins 27 are formed to be able to penetrate through insertion holes 28 formed on the upper surface of the backup holder 14. The load measuring element 20 is installed between the lower portion 16B of the pin main support 16 and the lower end of the pin sub support 17. A sliding roller 29 is rotatably supported on the lower portion 16B of the pin main support 16. The pin main support 16 is urged downward via an urging means such as a spring 30 so that the sliding contact roller 29 is always in contact with the cam 19.
[0019]
In addition, a long hole 31 is opened in the upper portion 16A of the pin main support 16, and a locking pin 32 provided integrally with a lower portion of the pin sub-support 17 is locked in the long hole 31, so that the pin main support 16 and The pin sub support 17 is integrated. The pin sub-support 17 is provided so as to be relatively movable in the vertical direction in the figure with respect to the pin main support 16 within a range in which the locking pin 32 moves in the longitudinal direction of the elongated hole 31. Supported by
[0020]
The motor 18 for driving the cam 19 is, for example, a stepping motor capable of controlling a rotation angle and a rotation speed, is capable of normal and reverse rotation, and is controlled by a controller 23. The cam 19 is a plate cam having a cam surface having a constant velocity curve that increases 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 for rotating 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-support 17, and the push-up force of the pin sub-support 17 as the pin support 15 is raised by the action of the cam 19, that is, the push-up pin 27 acts on the pellet 11. The thrust load is measured as needed, and the measured value (correctly, 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 device 21.
[0022]
Further, as shown in FIG. 1, the bonding head 2 is provided with a suction nozzle 13 above the pellet 11, and the suction nozzle 13 is attached to the surface of the adhesive sheet 12 by a linear motor 33 capable of adjusting the thrust. It is movably supported in a direction perpendicular to the direction.
The linear motor 33 has a permanent magnet 35 fixed to a holder (not shown) and a coil 36 fixed to the suction nozzle. The generated thrust of 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 increases, and decreases if the current value decreases.
[0023]
The controller 23 controls the generated thrust and the direction of the linear motor 33 via the current controller 34 based on the load measured value input from the load measuring device 21, that is, the thrust load, as described later, and controls the motor 18. Thus, the rotation angle and rotation speed of the cam 19 are controlled.
[0024]
Next, the detailed control by the controller 23 will be described with reference to a flowchart shown in FIG. 2 and a schematic cross-sectional view illustrating 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 clamping force applied to the pellet 11 is determined by the thickness and size of the pellet 11 to be bonded this time, and damages the pellet 11. The value is set to a value less than the range not given, and the value is obtained through experiments and the like.
[0026]
Next, the linear motor 33 is driven to move the suction nozzle 13 downward, and the suction surface at the tip thereof is brought into contact with the upper surface of the pellet (S2, FIG. 3A). At this time, the coil 36 of the linear motor 33 is supplied with a current capable of obtaining a thrust corresponding to the reference pickup load a to the suction nozzle 13, whereby the suction nozzle 13 in contact with the pellet 11 And a reference pickup load a is applied to the pellet 13.
[0027]
Next, the push-up pin 27 is raised by driving the motor 18 (S3). Then, at the same time that 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 tracing stylus 20 and the load measuring device 21 to obtain the measured value d (S4, FIG. )).
[0028]
Here, the obtained measured value d is compared with the upper limit value c of the pushing load (S5). If d> = c, it is determined that there is an abnormality, and the push-up pin 27 is lowered, and the push-up operation is stopped (S6). Then, the next pellet 11 is pushed up (S12). On the other hand, if d <c, the measured value d is compared with the reference thrust load b (S7). If d> = b, (db) is calculated and obtained (S8). Next, ((a- (db)) is obtained by calculation, 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. (C)). Due to this thrust correction, the pickup load applied to the pellet 11 by the suction nozzle 13 is (a− (db)), while the thrust load is the measured value d. The sum of the clamping pressures is (a + b), that is, the sum of the reference pickup load a and the reference push-up load b. As described above, the value obtained by adding the reference pickup load a to the reference pickup load a is: It is determined to be equal to or less than the range that does not damage the pellet 11, which is determined by 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, based on the output value of the encoder 22 connected to the motor 18, the push-up amount e of the push-up pin is detected, and the detected value e is compared with the maximum push-up amount s (S10). Then, when e> = s, the suction nozzle 13 sucks and holds the peeled pellet 11 and moves up, and transports it to a lead frame (not shown) for bonding (S11, FIG. 3D). . Further, 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, while the pellet 11 adhered to the adhesive sheet 12 is sucked while being pressed by the suction nozzle 13, when the pellet 11 is pushed up from the back surface of the adhesive sheet by using the push-up pin 27 and peeled off, the push-up pin 27 is used. The thrust load is measured, and if the measured value d exceeds the reference thrust load b, the suction motor 13 by the linear motor 33 reduces the pressing force (pickup load) by the suction nozzle by an amount exceeding the reference thrust load b. Feedback control of thrust. As a result, even if the thrust load applied to the pellet 11 fluctuates due to the rise of the thrust pin 27, the pressing force of the suction nozzle 13 is corrected, and the pellet 11 is stuck to the pellet 11 by the suction nozzle 13 and the thrust pin 27 during peeling of the pellet. The applied squeezing pressure is maintained at a load within a range that does not damage the pellet, and therefore, it is possible to prevent the pellet 11 from being damaged due to the peeling of the pellet. On the other hand, the bonding operation can be reliably performed.
[0031]
In the above-described embodiment, the measured value of the load measuring means composed of the load measuring element 20 and the load measuring device 21 is stored in, for example, a storage unit provided in the controller 23 so that the information is stored. Can be used as production management information. This is, for example, in the peeling operation accompanied with the pellet push-up, the maximum push-up load when the pellet 11 is peeled from the adhesive sheet 12 is obtained for all the pellets 11 for one adhesive sheet. Or a value obtained by calculating these values based on a predetermined formula is stored as a reference thrust load or upper limit allowable value information of the thrust load in the combination of the pressure-sensitive adhesive sheet and the pellet. The next time the same type of adhesive sheet and pellets are combined, the previously stored information is called up and used for the current peeling operation. This makes it possible to easily and quickly set the reference lifting load or the upper limit allowable value.
[0032]
Further, in the above-described embodiment, the pushing-up load by the pushing-up pin 27 is measured by the load measuring unit provided on the pellet pushing-up unit 1 side. However, this load measuring unit is attached to the bonding head 2 having the suction nozzle 13. It may be provided.
[0033]
Further, in the above-described embodiment, an example in which a linear motor is used as the actuator has been described. However, another actuator may be used as long as the actuator can adjust the thrust.
[0034]
In the above embodiment, the present invention is applied to a pellet bonding apparatus. However, in a flip chip bonder or the like, the present invention can be applied to a transfer apparatus that sucks a flip chip and transfers it to a collet of a bonding head. It is.
[0035]
【The invention's effect】
According to the present invention, even if the thrust load applied to the pellet fluctuates, damage to the pellet can be prevented and the bonding operation can be reliably performed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one 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 illustrating control of the controller of FIG. 1;
FIG. 3 is a schematic cross-sectional view illustrating an operation of pushing up a pellet.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 Pellet push-up unit 2 Bonding head 11 Pellet 12 Adhesive sheet 13 Suction nozzle 14 Backup holder 15 Pin support 16 Pin main support 16A Upper 16B lower 17 Pin sub-support 18 Motor 19 Cam 20 Load measuring element 21 Load measuring device 22 Encoder 23 Controller 24 Vacuum chamber 25 Passage 26 Small hole 27 Push-up pin 28 Insertion hole 29 Sliding contact roller 30 Spring 31 Long hole 32 Locking pin 33 Linear motor 34 Current controller 35 Permanent magnet 36 Coil

Claims (4)

The pellet adhered to the pressure-sensitive adhesive sheet is sucked from the pellet side while being pressed by a suction nozzle, and is pushed up from the back of the pressure-sensitive adhesive sheet using a push-up pin to peel off the pellet and bond the pellet to a substrate. In the pellet bonding method, a thrust load acting on the pellet is measured in accordance with a thrust operation of the thrust pin, and based on the measurement result, a pressing force applied to the pellet by the suction nozzle is caused by the suction operation of the pellet. A pellet bonding method characterized by controlling. 2. The pellet bonding method according to claim 1, wherein the pressing force is feedback-controlled so that the narrow pressure of the pellet narrowed by the suction nozzle and the push-up pin is within an allowable range. The pellet adhered to the pressure-sensitive adhesive sheet is suctioned from the pellet side while being pressed by a suction nozzle, and is pushed up from the back side of the pressure-sensitive adhesive sheet using a push-up pin to peel off the pellet and bond the pellet to a substrate. In the bonding apparatus, a load measuring means for measuring a pushing load acting on the pellet with the pushing-up operation of the pushing-up pin, and a pressing force applied to the pellet through the suction nozzle, and an actuator capable of adjusting the pressing force, Control means for controlling a pressing force of the actuator on the pellet based on a value measured by the load measuring means. 4. The pellet bonding apparatus according to claim 3, further comprising an output unit that outputs an alarm signal when a value measured by the load measurement unit exceeds an allowable range.

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