JPH06326147A - Wire bonding device - Google Patents

Abstract

PURPOSE:To provide a wire bonding device capable of easily conducting setting regarding loop control. CONSTITUTION:When information regarding loop height LH in the vertical direction of a wire loop and the length FL of a flat section in the horizontal direction of the wire loop is input by a keyboard 11, an arithmetic circuit 12 consisting of a microprocessor arithmetically operates a plurality of variables regarding movement in the relative vertical direction and horizontal direction between a capillary and a bonding point in the capirally while referring to a data table 13 on the basis of input information from the keyboard 11. A motor driver circuit 14 is supplied with a driving control signal (m) in the vertical direction of a bonding tool and an X-Y driver circuit 15 is supplied with a driving control signal (n) in the horizontal direction of the bonding tool on the basis of the arithmetic result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a first bonding point, for example, an electrode (pad) on a semiconductor chip, and a second bonding point, for example, an external lead arranged on a lead frame, in a semiconductor device assembling process. The present invention relates to a wire bonding device for connecting a wire using a wire.

[0002]

2. Description of the Related Art Conventionally, in a wire bonding apparatus for connecting an electrode on a semiconductor chip, which is a first bonding point, and a lead, which is a second bonding point, by using a gold wire or a wire such as copper or aluminum. A high voltage is applied between the tip of the wire protruding from the capillary as a bonding tool and the discharge electrode (electric torch) to cause a discharge, and the discharge energy melts the tip of the wire to the tip of the capillary. I try to form a ball. Then, the ball formed at the tip of the capillary is heated using ultrasonic waves and other heating means while applying a predetermined bonding load to the bonding point, and the wire is connected to the first bonding point. Is done as

Then, while the wire is paid out from the tip of the capillary, the capillary is relatively moved in accordance with a predetermined loop control, and the capillary is positioned immediately above the second bonding point. Further, the capillary is pressure-bonded to the second bonding point while applying a predetermined bonding load to the bonding point, heated by using ultrasonic waves and other heating means, and the wire is connected to the second bonding point. Made in.

[0004]

The shape of the wire that is bridged between the first bonding point and the second bonding point using the conventional wire bonding apparatus as described above is as follows.
Must be constant. FIG. 1 shows a loop control for making such a wire shape constant.

That is, FIG. 1 shows a movement locus of a capillary which moves when a wire is laid between a first bonding point and a second bonding point, and E is an electrode (pad) on a semiconductor chip. Is the first bonding point, and F is the second bonding point which is the external lead arranged on the lead frame. In FIG. 1, first,
After connecting a wire (not shown) to the first bonding point E, the capillary (not shown) is vertically lifted by a predetermined amount (first reverse height D) in the first step, and then in the second step. It is moved in the horizontal direction by a predetermined amount (first reverse amount C). Then, in the third step, the predetermined amount (the second reverse height B) is increased in the vertical direction, and in the fourth step, it is moved in the horizontal direction by the predetermined amount (the second reverse amount A). Then, the capillary is pulled up in the vertical direction from the first bonding point E until reaching the height of H ₁ , and then driven so as to draw in the direction of arrow G. This is the second capillary
After reaching just above the bonding point F, a predetermined bonding load is applied to the capillary, and the wire is thermocompression bonded.

In this way, when the wire is laid between the first bonding point E and the second bonding point F, the loop control as described above is performed, so that the first bonding point E
In step (first reverse height D) and second step (first reverse amount C), a "habit" due to bending is added to the wire to determine a predetermined loop height LH as shown in FIG. , The third step (second reverse height B) and the fourth step (second reverse amount A) determine the predetermined flat portion length FL, and the first bonding point E
A trapezoidal loop formed by the wire W is formed between and the second bonding point F.

By the way, when forming a trapezoidal loop by the wire W as shown in FIG. 2, it is necessary to drive the relative locus of the capillary with respect to the bonding point by the loop control as shown in FIG.
This includes a first reverse height D, which is a vertical relative movement amount driven in the first step, and a first reverse amount C, which is a horizontal relative movement amount driven in the second step. , A second reverse height B which is a relative movement amount in the vertical direction driven in the third step, and a second reverse height B which is a relative movement amount in the horizontal direction driven in the fourth step.
It is necessary to set the respective reverse amounts A, and further, the tool raising amount H ₁ which is the relative movement amount of the first bonding point E to the maximum raising point of the tool, the horizontal distance between the first bonding point and the second bonding point ( It is necessary to preset values such as the wire length L ₁ and the horizontal step (chip step) CH ₁ between the first bonding point and the second bonding point.

For these seven variables, it becomes necessary to input respective numerical values on the keyboard in advance during the bonding work. However, such an input work can be handled only by a so-called expert who is familiar with the action of the combination of the above-mentioned seven variables, and even an expert may repeat the measurement work many times for each variety. The adjustment work of each variable is forced.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and has a predetermined trapezoidal wire loop shape which is bridged between the first bonding point and the second bonding point. By inputting the values for the loop height LH and the predetermined flat portion length FL,
It is an object of the present invention to provide a wire bonding apparatus capable of calculating a numerical value of a combination of the above seven variables and driving a capillary based on the calculation result.

[0010]

According to the wire bonding apparatus of the present invention, after the wire is connected to the first bonding point, the capillary as a bonding tool is raised and the amount of wire necessary for forming the wire loop is fed out while the capillary is being extended. To move the wire above the second bonding point to connect the wire to the second bonding point, the vertical loop height of the wire loop and the horizontal flat portion length of the wire loop. A keyboard as an input means for inputting information regarding the above, and as a calculating means for calculating a variable relating to the amount of relative vertical movement and horizontal movement between the capillary and the bonding point based on the input information from this keyboard. Based on the operation circuit consisting of the microprocessor of and the operation result by this operation circuit, Characterized that relative drive and horizontal drive in the vertical direction between the Yapirari and the bonding point is provided with a driving means to be made. As a result, when forming the wire loop, it becomes possible to eliminate the need to set, for example, 7 variables for the complicated loop control as described above.

[0011]

Embodiments of the present invention will be described below with reference to FIGS.
Will be explained. FIG. 3 shows the configuration of the head unit HU in the wire bonding apparatus according to the present invention.

In FIG. 3, the drive arm 1 and the bonding arm 2 are independently oscillatably supported by a shaft 3. The bonding arm 2 holds an ultrasonic horn 5 having a capillary 4 as a bonding tool attached to the tip thereof for bonding connection via a support member 5a. An ultrasonic transducer 6 for generating ultrasonic waves is attached to an end of the ultrasonic horn 5,
The ultrasonic wave generated by the ultrasonic vibrator 6 is configured to be applied to the tip of the capillary 4 via the ultrasonic horn 5.

Contact points 7 and 7 ′ are provided near the rear end face of the ultrasonic transducer 6 and have the driving arm 1 and the bonding arm 2 respectively.
Is provided opposite to. A pair of solenoid units 8 are provided on the drive arm 1 and the bonding arm 2.
1 and 8'are provided so as to face each other, and when the solenoid units 8 and 8'are excited by a command from a control circuit (not shown), they are attracted to each other, and the bonding arm 2 with the shaft 3 as a fulcrum, in the direction of arrow ZZ 'in FIG. Be driven to. However, since the contacts 7 and 7'abut and act as a stopper, the positional relationship between the drive arm 1 and the bonding arm 2 is fixed and held.

Further, between the contacts 7 and 7'and the solenoid units 8 and 8 ', a pressure coil 9 and a magnetic core 9'which constitute electromechanical conversion means for applying a bonding load to a bonding point are driven. Detectors 10 and 1 which are provided so as to face the arm 1 and the bonding arm 2 and detect the displacement of the positional relationship between the drive arm 1 and the bonding arm 2 at the same time when the contacts 7 and 7'are separated.
0'is also provided facing each other.

A cam mechanism, which will be described later, is used as a vertical swing device for vertically swinging the drive arm 1 in the direction of arrow ZZ '. This vertical swinging device causes the drive arm 1 to move in the direction of arrow Z.
The bonding arm 2 also interlocks with the drive arm 1 by swinging in the Z'direction, and is configured to swing.

The bonding action of the head unit having the above structure will be described below with reference to FIG. FIG. 4A shows a lowered state by the capillary 4 (101) for performing the first bonding, and the ball IB formed at the tip of the wire 102 is pulled by a tension load device (not shown) to the capillary 4 (101). It is sufficiently pulled back to the side and comes close to the pad 104 arranged on the IC chip 103 by the uniform velocity circular motion of the capillary 4 (101).

Thereafter, as shown in FIG. 4 (b), the ball IB is
And the pad 104 collide with each other, and the ball IB moves to the capillary 4
The kinetic energy of (101) causes some deformation. At this time, the drive arm 1 continues its circular motion in the Z direction of FIG. 3 by a vertical swinging device (not shown), but the bonding arm 2 moves toward the capillary 4.
Since (101) and the upper surface of the pad 104 are in contact with each other via the ultrasonic horn 5 and are in a stopped state, the contacts 7 and 7'are separated by the continuous rotation of only the drive arm 1 in the Z direction of FIG. Then, the positional relationship between the drive arm 1 and the bonding arm 2 is displaced.

The displacement is detected by the detector 10, and the detection output causes the vertical swinging device to stop according to an instruction from a control circuit (not shown). After this stop, the pressurizing coil 9 as the pressurizing means is excited to generate a bonding load in the arrow direction shown in FIG. 4 (b). The load in the direction B is performed by applying ultrasonic waves in the direction of arrow B together with pressurization in the direction of arrow B and heating means (not shown). As shown in (), pressure bonding is performed until a predetermined crimping diameter D and crimping thickness WD are achieved, and a bonding action for the first bonding point is performed.

Then, according to the loop control shown in FIG. 1, the capillary 4 (101) is driven vertically and horizontally, and the capillary 4 (101) is positioned immediately above the second bonding point. Then, as shown in FIG. 4D, the capillary 4 (101) is lowered to move the capillary 4 (1
01), a bonding load is applied to crush a part of the wire 102 to form a flat portion. Here, ultrasonic waves are applied again to the tip of the capillary 4 (101),
The wire 102 is connected to the lead 105.

FIG. 5 is a block diagram showing an example of a control device for performing the above loop control. That is, reference numeral 11 in FIG. 5 is a keyboard, and the output of the keyboard 11 is supplied to an arithmetic circuit 12 composed of a microprocessor. A data table 13 is connected to the arithmetic circuit 12, data from the data table 13 is called according to an input value input by the keyboard 11, and arithmetic operation is performed by the arithmetic circuit 12. The control signals m and n are respectively supplied to the motor drive circuit 14 and the XY drive circuit 15 based on the calculation result.

The motor drive circuit 14 receives the control signal m and supplies a drive current mi to the motor 16,
To rotate. The cam 17 is rotated by the rotation of the motor 16.
Is configured to be driven, and the motor 16 and the cam 1
The cam mechanism CU is constituted by 7. With this cam mechanism CU, the drive arm 1 shown in FIG.
It is configured to swing up and down in the Z'direction.

On the other hand, the XY drive circuit 15 receives the control signal n and supplies the drive current ni to the XY drive mechanism 18, and the XY table 19 mounted on the XY drive mechanism 18. Are driven in the horizontal direction (X-Y direction). This XY
The head unit HU and the like in the wire bonding apparatus shown in FIG. 3 are mounted on the table 19.

As a result, the head unit HU is driven in the horizontal direction (X-Y direction) by the XY drive mechanism 18, and the capillary 4 in the head unit HU is swung in the vertical direction (Z direction) by the cam mechanism CU. Be moved. Therefore, the capillary 4 as a bonding tool
Undergoes a three-dimensional movement in the XY and Z directions, and a series of loop control actions from the first bonding point to the second bonding point as shown in FIG. 1 are performed.

The operation of the control device shown in FIG. 5 will be described below with reference to the flow chart shown in FIG. First, in the keyboard 11, the loop height LH of the wire W connected between the first bonding point and the second bonding point
Enter the numerical value of (step S1), then keyboard 1
1, the flat portion length FL of the wire W connected between the first bonding point and the second bonding point
Is input (step S2). From the XY coordinates of the first bonding point and the second bonding point, the wire length L ₁
Is calculated (step S3). Then, the calculation circuit 12 calculates a temporary tool lift amount h ₁ from the loop height LH input in step S1 (step S4).

The calculation circuit 12 determines the _first tool in FIG. 5 based on the temporary tool lift amount h ₁ calculated in step S4.
The data table 13-1 of FIG. This first data table 13-1, for example, increase the amount of correction value for the wire length L ₁ as illustrated graphically in FIG. 7 (±
d) is stored. As an example, the one shown in FIG. 7 is based on the equation y = a _n x + b _n (a _n and b _n are variables)
The correction value is shown when the loop height LH of the wire W is 250 μm and the chip step CH ₁ is 500 μm. Therefore, the optimum correction characteristics are selected from the first data table 13-1 according to the combination of the two parameters. Then, the correction value (± d) is added to the above-mentioned provisional tool rise amount, and the tool rise amount H ₁ is calculated (step S5).

Subsequently, the arithmetic circuit 12 calculates the first reverse height D from the loop height LH input in step S1 and the wire length L ₁ calculated in step S3 (step S6). After that, the arithmetic circuit 12 calculates the loop height LH input in step S1 and the loop height LH in step S3.
The second data table 13-2 is referred to based on the wire length L ₁ calculated in. This second data table 1
The optimum relationship of the first reverse amount C with respect to the wire length L ₁ is stored in 3-2 as shown in the graph of FIG. 8, for example. As shown in FIG. 8, as an example, y = C _n
Based on the equation x + D _n (C _n and D _n are variables), the wire W
Loop height LH is 250 μm, and chip step CH
Optimal first reverse amount C when ₁ is 500 μm
Is shown, which means that the second reverse amount C is calculated (step S7).

Next, the arithmetic circuit 12 uses the loop height LH input in step S1 and the wire length L ₁ calculated in step S3 to calculate the third data table 13
-3. In the third data table 13-3, for example, as shown in the graph of FIG.
Relationship of the second reverse height b of the second reverse amount a and the temporary provisional are stored for _one. As shown in FIG. 9, as an example, the loop height LH of the wire W is 250 μm based on the formula of y = E _n x + F _n (E _n and F _n are variables).
Chip step CH ₁ is 500 μm and flat part length FL
Shows the relationship between the second reverse amount and the second reverse height in the case where is 520 μm, and the provisional second reverse amount a and the provisional second reverse height b are calculated (step S8). become. Further, the arithmetic circuit 12 refers to the fourth data table 13-4 in step S9, and obtains the coefficient K1 from the flat portion length FL input in step S2. Fourth data table 13
-4 stores the relational data (y = Gx + H, G, H are variables) of the coefficient K1 with respect to the second reverse amount a and the second reverse height b in correspondence with the flat portion length FL as shown in FIG. Then, in the next step, the arithmetic circuit 12 uses the coefficient K1 found and uses the temporary second reverse amount a.
Then, the temporary second reverse height b is multiplied by the coefficient K1 to calculate the optimum second reverse amount A and second reverse height B (step S10).

Of the respective data calculated by the flow of steps S1 to S10, the data regarding the first reverse height D, the second reverse height B, and the tool rise H ₁ are as follows:
Control signals m are sequentially supplied to the motor drive circuit 14 in FIG. 5 according to a program sequence described later (step S11). Further, the calculated data regarding the first reverse amount C, the second reverse amount A, and the wire length L ₁ is sequentially supplied to the XY drive circuit 15 in FIG. 5 as a control signal n in accordance with a program order described later ( Step S11).

A data transmission program is stored in the arithmetic circuit 12, and as a first step of the data transmission program, a control signal relating to the first reverse height D calculated after completion of bonding to the first bonding point E. m is supplied to the motor drive circuit 14. As a result, the capillary 4 (101) is vertically driven by the amount corresponding to the first reverse height D. Next, as the second step of the data transmission program, the calculated first reverse amount C
The control signal n regarding the above is supplied to the XY drive circuit 15.
As a result, the capillary 4 (101) is horizontally moved to the second position.
The amount corresponding to the reverse amount C is moved. Similarly, the data transmission program has the second step calculated as the third step.
The control signal m relating to the reverse height B is sent to the motor drive circuit 1
4 and the capillary 4 (101) is vertically
The lift is driven by an amount corresponding to the reverse height B. Similarly, as a fourth step, the data transmission program supplies the calculated control signal n relating to the second reverse amount A to the XY drive circuit 15, and the capillary 4 (101) horizontally changes to the second reverse amount A. Moved by the corresponding amount.

Then, as a fifth step, the data transmission program supplies the control signal m relating to the calculated tool lift amount H ₁ to the motor drive circuit 14, and the capillary 4 (1
01) is raised to the highest point. Further, the motor sending program executes the calculated wire length L ₁ as the sixth step.
The control signal n is supplied to the XY drive circuit 15 and the control signal m is supplied to the motor drive circuit 14 at the same time based on the data on the tool and the tool ascending amount H ₁ , and the capillary 4 (101) is indicated by an arrow in FIG. It is driven along a circular arc of G and is controlled to be positioned directly above the second bonding point F.

As described above, the capillary 4 (101) located immediately above the second bonding point F is wire bonded to the second bonding point F according to a predetermined loop control.

[0032]

As is apparent from the above description, according to the wire bonding apparatus of the present invention, the vertical loop height of the wire loop and the horizontal flat portion length of the wire loop with respect to the keyboard are related. When information is entered, based on the information entered from this keyboard,
A variable relating to the amount of relative vertical movement and horizontal movement between the capillary and the bonding point is calculated by a calculation circuit composed of a microprocessor. Then, based on the calculation result, a relative vertical orbit and a horizontal orbit between the capillary and the bonding point are formed. Therefore, in forming a wire loop as in the conventional case, it is possible to eliminate the need to set a number of complicated variables relating to loop control by experience, and thus anyone can easily set loop control.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a locus of movement of a bonding tool in a wire bonding apparatus according to the present invention.

FIG. 2 is a side view showing a wire loop including a loop height and a wire length formed by the wire bonding apparatus according to the present invention.

FIG. 3 is a sectional view showing an example of a bonding head used in the wire bonding apparatus according to the present invention.

FIG. 4A to FIG. 4D are cross-sectional views illustrating a wire bonding process.

FIG. 5 is a block diagram showing an example of a controller of the wire bonding apparatus according to the present invention.

6 is a flowchart showing a flow of arithmetic processing performed by the arithmetic circuit of FIG.

7 is a characteristic diagram showing, as a graph, a data storage state of a first data table in the control device shown in FIG.

8 is a characteristic diagram showing, as a graph, a data storage state of a second data table in the control device shown in FIG.

9 is a characteristic diagram showing, as a graph, a data storage state of a third data table in the control device shown in FIG.

10 is a characteristic diagram showing, as a graph, a data storage state of a fourth data table in the control device shown in FIG.

[Explanation of sign]

 1 Drive Arm 2 Bonding Arm 3 Axis 4 Capillary 5 Ultrasonic Horn 6 Ultrasonic Transducer 7, 7'Contacts 8, 8'Solenoid Unit 9 Magnetic Core 9'Pressure Coil 10, 10 'Detector 11 Keyboard 12 Arithmetic Circuit 13 data table 14 motor drive circuit 15 XY drive circuit 16 motor 17 cam 18 XY drive mechanism 19 XY table CU cam mechanism HU head unit

Claims (4)

[Claims] 1. After connecting a wire to the first bonding point,
A wire bonding apparatus for moving a bonding tool above a second bonding point to connect the wire to the second bonding point while raising the bonding tool to feed out a required amount of wire for wire loop formation, Input means for inputting information about the vertical loop height of the wire loop and the horizontal flat portion length of the wire loop, and between the bonding tool and the bonding point based on the input information from the input means. Computation means for computing variables relating to relative vertical and horizontal movement amounts, and relative vertical drive and horizontal directions between the bonding tool and the bonding point based on the computation result by the computation means. And a drive means for driving the wire Location. 2. The driving means is configured to perform a relative vertical drive and a horizontal drive between the bonding tool and the bonding point at least two times repeatedly. 1. The wire bonding apparatus according to 1. 3. A variable relating to the relative amount of movement in the vertical and horizontal directions between the bonding tool and the bonding point calculated by the calculation means is a relative movement in the vertical direction driven in the first step. A first reverse height which is an amount, a first reverse amount which is a relative amount of horizontal movement driven in a second step, and a second which is a relative amount of vertical movement driven in a third step. A reverse height, a second reverse amount that is a relative movement amount in the horizontal direction driven in the fourth step, and a tool raising amount that is a relative movement amount between the first bonding point and the highest point of the bonding tool, The wire bonding apparatus according to claim 1 or 2, wherein the wire length is a relative movement amount between the first bonding point and the second bonding point. 4. The input means is a keyboard, and numerical values relating to the vertical loop height of the wire loop and the horizontal flat portion length of the wire loop are input to the keyboard. Claim 1
The wire bonding apparatus according to claim 3.