JP4459478B2 - Bonding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bonding apparatus used for mounting a semiconductor device.
[0002]
[Prior art]
A bonding apparatus described in Japanese Patent Laid-Open No. 2000-183114 as a first prior art will be described with reference to FIG.
In FIG. 5, the bonding apparatus has a bonding part 9 provided with a bonding tool 7 that operates by adsorbing a chip 5 as an electronic component, a driving part 20 that drives the bonding part 9, and a lower part of the bonding part 9. And a stage 10 on which the substrate 1 is placed.
The bonding portion 9 is provided with a bracket 18 that is engaged with the vertical portion via the linear guide 12 and is suspended on the horizontal portion by the spring 14, and a load cell 16 for detecting the pressure applied by the bonding tool 7. It has been.
[0003]
The drive unit 20 includes a Z-axis drive mechanism and a θ-axis movement mechanism. The Z-axis drive mechanism is configured such that the rotation shaft of the motor 21 fixed to the holding plate 25 is coupled to the ball screw 23 and screwed to the ball screw 23. The extended portion of the nut 24 is fixed to the plate 30. Note that the holding plate 25 and the plate 30 are connected by a spring 27. The θ-axis moving mechanism includes a θ-axis motor 32 fixed to the upper surface of the plate 30 and a θ-axis moving mechanism 34 fixed to the plate 30.
[0004]
The operation of the bonding apparatus configured as described above will be described with reference to FIG. The chip 5 is supplied to the bonding tool 7 and the substrate 1 is supplied to the stage 10, and alignment is performed by image recognition (not shown).
Next, the motor 21 is actuated to lower the nut 24 at a high speed, stop just before the chip 5 and the substrate 1 are in contact, and operate the motor 21 at a low speed while measuring the change in the output value of the load cell 16. And the contact of the substrate 1 is detected. Subsequently, the motor 21 is operated until a predetermined pressure is applied, and bonding is performed.
[0005]
A bonding apparatus described in Japanese Patent Application Laid-Open No. 11-121481 as a second prior art will be described with reference to FIG. In FIG. 6, the same reference numerals as those in FIG. 5 denote the same or corresponding parts, and the description thereof is omitted.
The bonding apparatus includes a bonding unit 40 including a bonding tool 7 that operates by adsorbing the chip 5, a driving unit 50 that drives the bonding unit 40, and a balance unit 60 that cancels the weight of the bonding unit 40. Yes. The bonding unit 40 includes a guide 41 for guiding the bonding tool 7, a holder 45 for inserting a compression spring 43 for applying pressure to the bonding tool 7, and a load cell 49 in which the holder 45 is connected via a holding plate 47. The compression spring 43 is formed so as to generate initial deflection when the bonding tool 7 is not pressurized.
[0006]
In the drive unit 50, the rotating shaft of the motor 21 fixed to the support column 53 is coupled to the ball screw 23, the ball screw 23 is screwed to the plate 51, and the upper end of the load cell 49 is fixed to the plate 51.
The balance portion 60 is formed so that the balance weight 61 is connected to the bonding portion 40 via a wire 65 and the wire 65 travels in the pulley 63.
[0007]
The operation of the bonding apparatus configured as described above will be described with reference to FIG. The chip 5 is supplied to the bonding tool 7 and the substrate 1 is supplied to the stage 10 to perform image recognition and alignment.
[0008]
Next, the bonding tool 7 is moved down at high speed by operating the motor 21, stopped just before the chip and the substrate 1 come into contact with each other, and the motor 21 is operated at low speed while measuring the change in the output value of the load cell 49. And the contact of the substrate 1 is detected. Subsequently, the motor 21 is operated until a predetermined pressure is applied, and bonding is performed.
[0009]
[Problems to be solved by the invention]
However, the above-described bonding apparatuses according to the first and second conventional techniques have the following problems.
That is, in the first prior art, after the chip 5 and the substrate 1 are in contact with each other and the change in the output value of the load cell 16 is detected, the minute displacement amount ΔL that is lowered until the motor 21 stops and the spring of the bonding portion 9 are detected. The initial pressure is determined by a constant multiplied value.
However, since the spring constant of the bonding portion 9 is determined by the spring constant of the load cell 16 and this spring constant is very high, from several thousand (N / mm) to several tens of thousands (N / mm), bonding with a low initial pressure can be performed. There wasn't.
In addition, the resolution of the load control of the bonding tool 7 is determined by the multiplication value of the spring constant of the bonding portion 9 and the minimum movement unit of the bracket 18 that moves the bonding tool 7 up and down.
However, since the spring constant of the bonding portion 9 is large as described above, a load resolution as small as about 0.01 N cannot be realized.
[0010]
In the second prior art, since the initial load corresponding to the initial deflection of the compression spring 43 is usually applied to the number of N to several tens of N at the moment when the bonding tool 7 contacts the chip 5, the control below the initial overload is performed. could not.
[0011]
The present invention has been made to solve the problems of the first and second prior arts, and an object of the present invention is to provide a bonding apparatus capable of controlling the applied pressure with a high accuracy from a low load.
[0012]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a bonding apparatus, a stage for holding a substrate, a bonding portion for holding an electronic component bonded to the substrate, and an elastic member having one end connected to the bonding portion and having a predetermined elastic constant. A unit connected to the other end of the elastic member, a drive unit that moves the unit in the vertical direction with respect to the substrate, a first storage unit that stores an elastic constant of the elastic member, and the elasticity Based on detection means for detecting a change in the length of the member, a change in the length of the elastic member based on a detection value of the detection means, and the elastic constant stored in the first storage means And a calculating means for calculating the pressure applied to the bonding portion.
According to such a bonding apparatus, the calculation means obtains the pressure applied to the bonding portion based on the change in the length of the elastic member and the elastic constant of the elastic member, so the pressure value of the bonding portion such as a load cell is detected. This eliminates the need for pressure detecting means.
Therefore, since the initial applied pressure and load resolution of the bonding part are determined based on the elastic constant of the elastic member between the unit and the bonding part, the initial applied pressure can be reduced by selecting an appropriate value for the elastic constant of the elastic member, In addition, the load resolution accuracy can be improved.
[0013]
According to a second aspect of the present invention, there is provided a bonding apparatus comprising: a stage for holding a substrate; a bonding portion for holding an electronic component bonded to the substrate; and a first elastic member having one end connected to the bonding portion and having a predetermined elastic constant. An elastic member, a pressure detecting means for detecting a pressure applied to the bonding portion connected to the other end of the first elastic member, and a second elastic member connected to the pressure detecting means at one end. And a unit connected to the other end of the second elastic member, and a drive unit for moving the unit in the vertical direction with respect to the substrate held on the stage.
According to such a bonding apparatus, the composite elastic constant is determined based on the series of the elastic constant of the pressure detection means and the elastic constant of the first elastic member. Therefore, by selecting the elastic constant of the elastic member to an appropriate value, There is an effect that the applied pressure can be lowered and the accuracy of the load resolution can be improved.
Then, for example, by selecting the elastic coefficient of the first elastic member sufficiently smaller than the elastic constant of the pressure detection means, the initial pressure of the bonding tool and the pressure resolution can be determined by the elastic constant of the first elastic member. There is an effect that can be set freely.
[0014]
The elastic member of the bonding apparatus according to the third invention is a spring according to the first or second invention, and comprises a tension spring and a compression spring.
According to such a bonding apparatus, there is an effect that it is possible to apply a pressing force more than the weight of the bonding portion as an initial pressing force when the electronic component is pressed against the substrate by the compression spring.
[0015]
According to a fourth aspect of the present invention, there is provided a bonding apparatus according to the first or third aspect, wherein the bonding unit and the unit are slidably engaged with each other, and a value based on the length of the elastic member is stored. A storage unit, a command generation unit that generates a command to move the bonding unit to a predetermined position by a driving unit, and a difference between a value detected by the detection unit and a value stored in the second storage unit is obtained. It comprises a difference calculating means and a correcting means for correcting the command value of the command generating means based on the difference between the difference calculating means.
According to such a bonding apparatus, the command calculation means moves the bonding portion to a predetermined position, and the difference calculation means calculates the difference between the detection value of the detection means and the storage value of the second storage means. The correcting means corrects the command value of the command generating means.
Therefore, since the command value of the command generating means corrects the influence of the resistance of the sliding portion, there is an effect that the bonding portion can be accurately aligned based on the command value.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1.
An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view of the bonding apparatus.
In FIG. 1, a bonding apparatus includes a substantially inverted L-shaped base column 101, a substantially inverted concave unit 150 connected to the base column 101, a drive unit 120 that raises and lowers the unit 150, and a unit 150, a bonding unit 180 slidably connected to the first elastic member via a spring unit 160 as a first elastic member, a detection unit 200 for detecting the spring length of the spring unit 160 between the bonding unit 180 and the unit 150, A stage 10 for placing the substrate 1 and moving the position of the substrate 1 by an X-axis, Y-axis, and θ-axis drive mechanism (not shown) is provided.
[0017]
The drive unit 120 has a motor 121 fixed to the upper portion of the base pillar 101, and is fixed to the rotating shaft of the motor 121, and a ball screw 123 provided in the Z-axis direction is screwed into the screw hole 150 e of the unit 150. The vertical portion of the unit 150 is formed to be slidable in the Z-axis direction of the base pillar 101 via the linear guide 152.
[0018]
The spring part 160 includes a coil-like first tension spring 161 and a second tension spring 163 that pull up the bonding part 180, and a coil-like compression spring 165 that pushes down the bonding part 180. The reason why the tension springs 161 and 163 are provided on both sides of the compression spring 165 is to prevent an unbalanced spring force from being applied to the bonding portion 150.
Further, the first tension spring 161, the second tension spring 163, the compression spring 165, and spring constants K ₁ (N / mm), K ₂ (N / mm), and K ₃ (N / mm) as elastic constants are set. Measured, the combined spring constant K ₀ (N / mm) of the three springs is the sum of the spring constants K ₁ , K ₂ , K ₃ . For example, if the spring constant K ₁ = K ₂ = 2 (N / mm) and K ₃ = 32 (N / mm), then K ₀ = 36 (N / mm).
[0019]
The bonding unit 180 includes a bonding tool 182 that sucks the chip 5 as an electronic component, and a tool holder 184 that is guided in the Z-axis direction by the linear guide 155 and holds the bonding tool 182.
[0020]
The detection unit 200 forms detection means, and is fixed to the horizontal detection plate 201 provided on the bonding holder 184 and the upper end surface of the unit 150, and also measures the distance in the Z-axis direction to the detection plate 201. For example, the length of the spring portion 160 is detected as a value based on the length of the spring portion 160.
[0021]
The control unit 300 is a part that controls the movement of the entire apparatus, and a calculation unit 131 that performs calculation based on detection values by the displacement sensors 203 and interfaces (I / F) 303 and 305 that incorporate detection values of the encoder 122 of the motor 121. And a storage unit 307 as first and second storage means.
The camera 400 can capture an image in the vertical direction of the Z axis, and is configured to be movable in the X axis and Y axis directions by an X axis and Y axis drive mechanism (not shown).
[0022]
Next, the operation of the bonding apparatus configured as described above will be described with reference to FIGS. FIG. 2 is a flowchart showing the operation of the bonding apparatus.
Using a keyboard (not shown), the spring length Zr (mm) of the spring part 160 having the bonding part 180, the combined spring constant K ₀ (N / mm) of the spring part 160 measured in advance, the chip 5 and the substrate 1, the Z axis downward displacement increase amount ΔZ (mm), the chip 5 and substrate 1 pressurization value F _sf (N), and the pressurization allowable range ΔF _s (N) are input. To be stored in the storage unit 307 (step S100).
The chip 5 is attracted to the lower end of the bonding tool 182 and the substrate 1 is attracted to the stage 10. The camera 400 is inserted between the substrate 1 and the chip 5.
[0023]
The control unit 300 drives the motor 121 to lower the bonding tool 182 to A _r (mm) as a command value in the Z-axis direction (command generation means of claim 4) that becomes the image recognition position of the camera 400 (step S101). ). In the command value A _r (mm) of the motor 121 in the Z-axis direction, the detection value Z _a (mm) of the displacement sensor 203 and the length Z _r (mm) of the spring part 160 stored in the storage unit 307 are linear. Due to the sliding resistance of the guide 155, it may not be equal.
Therefore, the command value A _ra (correcting means of claim 4) of the motor 121 considering the sliding resistance of the linear guide 155 is set by the following equation.
A _ra = A _r − (Z _r −Z _a ) (1)
[0024]
A camera 400 is inserted between the chip 5 and the substrate 1, performs image recognition between the chip 5 and the substrate 1, measures the amount of relative displacement between the chip 5 and the substrate 1, and does not show the stage 10 X The position of the substrate 1 is adjusted by the axis, Y axis, and θ axis drive mechanisms (step S103). The control unit 300 drives the motor 121 to move the tip of the bonding tool 182 to a position immediately before the tip 5 and the substrate 1 that have been taught in advance contact with each other, and then the detected value Z _n (mm) of the displacement sensor 203. Is stored in the storage unit 307 (step S105), and the motor 121 is driven at a low speed, thereby causing the bonding tool 182 to approach the substrate 1 at a low speed (step S107), and the detected value Z of the displacement sensor 203 in this approach operation. _{When t} (mm) satisfies the following equation, it is considered that the substrate 1 and the chip 5 are in contact with each other, and a contact signal St is generated (step S109).
Z _t ≦ Z _n −ΔZ (2)
ΔZ: displacement increase amount (mm) stored in the storage unit in step S100
Z _n : value of the displacement sensor (mm) immediately before the contact in step S105
[0025]
The control unit 300 stops the approach operation of the bonding tool 182 by stopping the driving of the motor 121 by the contact signal St (step S111), and the current displacement detected by the displacement sensor 203 when the bonding tool 182 is stopped. Z _sa (mm) is stored in the storage unit 308.
The calculation unit 301 of the control unit 300 moves the bonding tool 182 in the downward direction Z up to the pressing force F _Sf (N) stored in the storage unit 307 so that the bonding tool 182 presses the chip 5 in step S100. _e (mm) is calculated by the following formula, and the bonding tool 182 is lowered by driving the motor 121 based on the movement amount Z _e to pressurize the chip 5 to the substrate 1 (step S113).
Z _e = Z _sa − (Z _n −F _sf / K ₀ ) (3)
Z _n : value of the displacement sensor (mm) immediately before the contact in step S105
K ₀ : Composite spring constant (N / mm) stored in the storage unit in step S100
[0026]
The control unit 300 detects the current displacement Z _r (mm) of the displacement sensor 203 at the time of pressurization, and uses the allowable pressurization range ΔF _s (N) stored in the storage unit 307 in advance. Confirmation (step S115).
Z ₁ ≦ Z _r ≦ Z ₂ (4)
_{Here, Z 1 = Z n -F Sf} / K 0 -ΔF s / K 0
Z ₂ = Z _n −F _Sf / K ₀ + ΔF _s / K ₀
The control unit 300 determines whether or not the above expression (4) is satisfied. If satisfied, the bonding tool 182 is heated, the solder is melted, and the chip 5 is bonded to the substrate 1 (step S117). Step S113 is executed to pressurize again.
[0027]
The minimum value F _tmin (N / mm) of the initial pressurizing force of the bonding tool 182 according to this embodiment is expressed by the following formula, assuming that the time from the generation of the contact signal St to the stop of the bonding tool is t _m (s). It becomes.
F _tmin = K ₀ × V _a × t _m + ΔZ × K ₀ (5)
Here, V _a : Approach speed of the bonding tool (mm / s)
ΔZ: displacement increase amount (mm) stored in the storage unit in step S100 K ₀ : composite spring constant (N / mm) stored in the storage unit
[0028]
Further, the pressure accuracy F _p (N) of the bonding tool 182 is a product of Z _min (mm) as the minimum movement unit of the bonding tool 182 and the combined spring constant K ₀ .
Pressure F _min, accuracy Fp applied pressure can be changed by the combined spring constant K _0, by decreasing the combined spring constant K _0, easily reduce the minimum value F _min of the initial pressure, pressure The accuracy Fp can be improved.
[0029]
Embodiment 2.
Another embodiment of the present invention will be described with reference to FIG. FIG. 3 is a perspective view of the bonding apparatus. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted.
In FIG. 3, in the bonding apparatus, a spring portion 160 is suspended from a base 505 provided at the lower end of the load cell 503, and the upper portion of the load cell 503 is attached to the unit 150 by two tension springs 501 (second elastic members). By being pulled, the upper portion of the load cell 503 is formed so as to come into contact with the lower end of the unit 150 by a predetermined pressing force. Note that the detection value of the load cell 503 is input to the I / F 311.
A combined spring constant K _LO of the spring constant K _L of the load cell 503 and the spring constant K ₀ of the spring portion 160 is expressed by the following equation.
K _LO = K _L · K ₀ / (K _L + K ₀ ) (6)
For _{example, K 0 = 36 (N /} mm), as in the K L = 10000 (N / mm ), if _{K 0 «K L, K LO ≒} K 0 , and the spring constant of the bonding portion 180, the spring It is formed so as to be determined by the spring constant of the portion 160.
[0031]
The operation of the bonding apparatus configured as described above will be described with reference to FIGS. FIG. 4 is a flowchart showing the bonding operation. In FIG. 4, steps denoted by the same reference numerals as those in FIG.
First, with a keyboard (not shown), the spring length Zr (mm) of the spring part 160 having the bonding part 180, the combined spring constant K _L0 (N / mm) of the spring part 160 measured in advance, the threshold value F ₃ (N), the pressurization value F _sf (N) of the chip 5 and the substrate 1 and the allowable pressurization range ΔF _s (N) are inputted and stored in the storage unit 307 (step S200).
[0032]
The control unit 300 drives the motor 121 to move the bonding tool 182 to a position immediately before the chip 5 and the substrate 1 that have been taught in advance contact with each other, so that the chip 5 and the substrate 1 are not in contact with each other. Thus, the detected value F _n (N) of the load cell 503, that is, the initial load is stored in the storage unit 307 of the control unit 300 (step S205), and the motor 121 is driven at a low speed, whereby the bonding tool 182 is attached to the substrate 1. To approach at low speed (step S107).
[0033]
The control unit 300 reads the detected value F _ap (N) of the load cell 503 in the approach operation, and obtains the change amount ΔF ₂ (N) of the value of the load cell 503 by the following equation.
ΔF ₂ = F _ap −F _n (7)
Here, F _n : the detection value (N) control unit 300 of the load cell immediately before the contact in step S205 is compared with the contact detection threshold F ₃ (N) in which ΔF ₂ is stored in the storage unit 307, ΔF ₂ ≧ F ₃ and it is determined whether or not if (step _{S109), ΔF 2 ≧ F 3} , to stop the motor 121 generates a contact signal St, stops the approach operation (step S211).
[0034]
The control unit 300 stores the current pressure F _a2 (N) detected from the load cell 503 when the bonding tool 182 is stopped in the storage unit 307. The pressure F _e (N) required until the bonding tool 182 stored in the storage unit 307 reaches the pressure F _sf (N) for pressing the chip 5 is calculated by the following equation (8), and the pressure F _e In order to obtain the required amount of drop Z _e (mm) of the bonding tool 182, the chip 5 and the substrate 5 are pressurized by driving the motor 121 based on the required drop amount Z _{e according} to the following equation (9). (Step S213).
F _e = F _sf − (F _a2 −F _n ) (8)
Z _e = F _e / K _L0 (9)
Here, K _L0 : Composite spring constant (N / mm)
[0035]
The control unit 300 detects the current pressurizing force F _ap (N) from the load cell 503, the pressurization allowable value ΔF _s (N) and the pressurizing force F _sf stored in the storage unit 307 in step S 200, and step 205. The pressure F _ap (N) is confirmed by the following equation using the detected value F _n of the load cell 503 immediately before the contact stored in the storage unit 307 (step S215).
F ₁ ≦ F _ap ≦ F ₂ (10)
Here, F ₁ = F _sf + F _n −ΔF _s
F ₂ = F _sf + F _n + ΔF _s
[0036]
The controller 300 determines whether or not the above expression (10) is satisfied (step S215). If satisfied, the bonding tool 182 is heated, the solder is melted, and the chip 5 is bonded to the substrate 1 (step S117).
On the other hand, if the above equation (10) is not satisfied in step S215, step S213 is executed again to apply pressure.
[0037]
In Embodiments 1 and 2, the spring portion 160 uses one tension spring and one compression spring, and the spring portion 160 can be made compact by inserting the tension spring in the compression spring.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a bonding apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an operation of the bonding apparatus of FIG.
FIG. 3 is a perspective view showing a bonding apparatus according to another embodiment of the present invention.
4 is a flowchart showing the operation of the bonding apparatus of FIG.
FIG. 5 is a front view showing a bonding apparatus according to a first prior art.
FIG. 6 is a front view showing a bonding apparatus according to a second prior art.
[Explanation of symbols]
1 substrate, 5 chips, 120 drive unit, 150 unit, 160 spring unit (elastic member), 180 bonding unit, 201 detection plate, 203 displacement sensor.

Claims (2)

A stage for holding a substrate;
A bonding part for holding an electronic component bonded to the substrate;
One end is connected to this bonding part, and an elastic member composed of a tension spring and a compression spring having a predetermined elastic constant,
A unit connected to the other end of the elastic member;
A drive unit for moving the unit in the vertical direction with respect to the substrate;
First storage means for storing an elastic constant of the elastic member;
Detecting means for detecting a change in length of the elastic member;
A computing means for computing a pressure applied to the bonding portion based on a change in the length of the elastic member based on a detection value of the detecting means and the elastic constant stored in the first storage means;
A bonding apparatus comprising: A sliding part in which the bonding part and the unit are slidably engaged;
Second storage means for storing a value based on the length of the elastic member;
Command generating means for generating a command to move the bonding unit to a predetermined position by the driving unit;
A difference calculation means for obtaining a difference between the detection value of the detection means and the value stored in the second storage means;
Correction means for correcting the command value of the command generation means based on the difference of the difference calculation means;
The bonding apparatus according to claim 1 , further comprising:

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