JPH11243113A - Wire bonding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire bonding device which is capable of performing uniform bonding at high speed without the variance in ball pressing diameter and bonding strength. SOLUTION: A measuring means 20 is provided to obtain information on the distance to an IC chip 12 as a component to be bonded which is arranged on a bonding stage 5, the distance to respective bonding points of the IC chip 12 are calculated according to the distance information obtained by this measuring means 20, and a bonding arm 2 is controlled on the basis of the calculated distances to the respective bonding points for making a bonding connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for assembling a semiconductor device in which a first bonding point, for example, an electrode (pad) on a semiconductor chip (IC chip) as a semiconductor component, and a second bonding point, for example, a frame. In particular, the present invention relates to a wire bonding apparatus that measures a distance to a bonding point in wire bonding and performs bonding based on the measured distance information.

[0002]

2. Description of the Related Art FIG. 7 is a view showing the configuration of a conventional wire bonding apparatus, FIG. 8 is a view showing a tool height (tool height) and a search level in a conventional wire bonding apparatus, and FIG. ) Is a velocity waveform when the bonding arm of the conventional wire bonding apparatus is lowered,
FIG. 10B shows a locus of the bonding arm when the arm is lowered. FIG. 10 shows a position of the IC chip attached to the lead frame, and a dotted line shows a position of a regular IC chip to be attached. 11 (a) and 11 (b) are views including a partial cross section for explaining a wire bonding step.

[0003] As shown in FIG. 7, a conventional wire bonding apparatus has a camera 1 as an imaging means, an ultrasonic vibrator and an ultrasonic horn, and has a capillary 2a mounted at the tip thereof as a bonding means. A bonding head including a bonding arm 2, a driving unit 3 including the bonding arm 2 as the bonding unit and driving the bonding arm 2 up and down about a support shaft by a linear motor or a cam, and a tip of the bonding arm 2 Capillary 2a attached to
Position detecting means (not shown) for detecting the position of the XY table 4 as positioning means for mounting and positioning the bonding head and two-dimensionally moving and positioning the bonding head in the X direction and / or the Y direction; A bonding stage 5 disposed below the arm 2 for swinging the bonding arm 2 to perform a bonding operation by a capillary 2a, an image recognition unit 8 receiving an output from the camera 1, and an output from the image recognition unit 8; A monitor 9 as a display means for receiving the information, a controller unit 10 including a microprocessor, and the driving means 3 and the XY unit according to a command signal from the controller unit 10.
And a drive unit 11 for issuing a drive signal to the table 4.

As shown in FIGS. 7 and 10, a conventional wire bonding apparatus includes a plurality of pads 12a formed on a plurality of square or rectangular IC chips 12 and a plurality of lead frames L＼F. Bonding connection is performed between the lead 15 and the lead 15 using a wire.

In this wire bonding apparatus, the lead frame L＼F is loaded onto the bonding stage 5 heated by a transport means (not shown) at the start of the operation, and the first IC chip 12 is moved to the bonding operation position. Position. The heating of the bonding stage 5 is performed by a heater 5a to heat a lead frame L / F, which is a part to be bonded.

When the bonding arm 2 and the XY table 4 are positioned on the bonding stage 5, the bonding operation is performed on the earliest IC chip 12.

However, in the wire bonding apparatus, it is necessary to set various conditions, that is, set bonding parameters before performing a series of bonding operations.

The bonding parameters include a tool height (tool height), a search level, a search speed, and the like. Hereinafter, these bonding parameters will be described with reference to FIG.

As shown in FIG. 8, the tool height refers to a pad on the IC chip 12 which is a first bonding point from an origin position (0 in FIG. 8) of the capillary 2a attached to the tip of the bonding arm 2. 8 (La in FIG. 8) and the lead 1 as the second bonding point.
5 (Lb in FIG. 8). The origin position of the capillary 12a is set in advance.

The tool height is set by lowering the bonding arm 2 at a low speed from a preset origin position of the bonding arm 2 so that the tip of the capillary 2a is a bonding surface, that is, a pad (12a in FIG. 10) or a lead of the IC chip 12. The distance up to contact with the position 15 is determined by counting the output of an encoder serving as a position detecting means for detecting the position of the bonding arm 2.

As shown in FIGS. 9A and 9B, the search level S is the height of the capillary 2a when the lowering speed of the bonding arm 2 changes from high speed to low speed.

FIG. 9A shows a velocity waveform when the bonding arm 2 descends during bonding, and FIG. 9B shows the trajectory of the capillary 2a.

The bonding arm 2 descends at a high speed, decelerates before the search level S, descends from the search level S at the search speed (Vs in FIG. 9A), and locks the ball at the tip of the capillary 2a. 19 contacts the pad at the first bonding point. Further, at the second bonding point, the wire 18 (see FIG. 11D) which is drawn out from the tip of the capillary 2a comes into contact with the surface of the lead 15.

The search level S is set differently between the IC chip 12 and the lead 15, as shown in FIG. That is, as shown in FIG.
Surface and the search level from the surface of the lead 15 (S1 in FIG. 8, S2) to the height of (h _1, h ₂ in FIG. 8) is usually 1
It is set at 50 μm to 200 μm.

The above search level S is set for the following reason. That is, since the height of the IC chip 12 mounted on the lead frame L / F or the like is bonded by a conductive bonding material such as resin, solder, or gold, the IC chip 12 may vary due to a variation in the thickness of the bonding material. The thickness of the chip 12 itself varies and differs for each IC chip 12. In addition, since the thickness of the bonding material is not uniform, the IC chip 12 may be mounted to be inclined in the height direction.

On the other hand, the lead 15 shown in FIG. 10 also differs in the height of the surface of the lead 15 due to variations in the thickness of the lead member, warpage of the lead, and the like.

Therefore, since the height of the IC chip 12 and the lead 15 to be bonded vary, the search level S as a bonding parameter is not sufficient.
Needs to be set in consideration of variations in the height of the IC chip 12 and the height of the leads 15.

The search speed Vs is a lowering speed of the capillary 2a below the search level, that is, below the height of the capillary 2a when the lowering speed of the bonding arm 2 changes from high speed to low speed. As shown in FIG. 9, the search speed Vs is for reducing the initial deformation amount of the ball 19 due to the impact when the ball 19 contacts the pad. This search speed is 10 μm
/ Msec.

Next, a bonding process using a conventional wire bonding apparatus will be described.

As shown in FIG. 10, the IC chip 12 is adhered on the lead frame L＼F with a conductive bonding material, but the position where the IC chip 12 is adhered is a predetermined position to be adhered. (The position of the IC chip 12 'indicated by a dotted line in FIG. 10). Therefore, before performing wire bonding, the IC chip 12 (pad 12
a) is captured by the camera 1, and the captured signal is input to the image recognition unit 8 to perform image processing to perform IC processing on the IC chip 12.
The position of the pad 12a to be actually bonded of the IC chip 12 is calculated by calculating the amount of displacement from the predetermined position.

The lead 1 serving as a second bonding point
Since the position of 5 is also shifted from the normal position, a plurality of leads 15 are imaged by the camera 1 attached and fixed to the bracket 21 provided on the XY table 4, and the image signals are image-processed and the actual image signals are processed. The position of the lead 15 is determined. The normal position of the IC chip 12 ′ and the lead 15 is
This is a position where a position on the coordinates of the XY table 4 is set in advance as a bonding parameter.

The correction of these deviation amounts is also set as a bonding parameter.

FIGS. 11 (a) to 11 (d) are explanatory views of a wire bonding process performed after setting the bonding parameters by a conventional wire bonding apparatus.

As shown in FIGS. 11 (a) and 11 (b), a discharge is caused between the tip of the wire 18 sent to the tip of the capillary 2a and the discharge electrode 16 for a predetermined time, and the tip of the wire 18 is moved. The ball 19 is formed by melting, and the wire 18 is held at the tip of the capillary 2a, and the capillary 2a is connected to the pad 1 on the IC chip 12 at the first bonding point.
2a.

Next, the capillary 2a is lowered at a high speed, decelerated from just before the search level S shown in FIG. 9, and lowered at the search speed Vs from the search level S, as shown in FIG.
As shown in (1), the ball 19 at the tip of the capillary 2a is pressed against the pad 12a. After detecting the contact of the ball 19 with the pad 12a by the position detecting means, a predetermined bonding load is applied, and at the same time, ultrasonic vibration is applied to the tip of the capillary 2a via the ultrasonic horn of the bonding arm 2. The wire 18 is connected to the pad 12a.

Subsequently, as shown in FIG. 11D, the capillary 2a is raised according to a predetermined loop control, and is moved in the direction of the lead 15 which is the second bonding point.

Next, the capillary 2a is lowered at a high speed,
The wire 18 at the tip of the capillary 2 a is lowered from the search level S at the search speed Vs and pressed against the lead 15.

After detecting the contact of the wire 18 with the lead 15 by the position detecting means, a predetermined bonding load is applied, and at the same time, an ultrasonic vibration is applied to the tip of the capillary 2a via an ultrasonic horn to lead. A wire 18 is connected to 15.

Thereafter, the capillary 2a is raised, the wire 18 is projected to a predetermined length at the tip of the capillary 2a, the wire cut clamp 14 is closed at a preset rising position of the capillary 2a, and the wire 18 on the lead 15 is cut. Then, the wire 18 is extended to the tip of the capillary 2a by a predetermined length (amount of wire feed).

Next, the position of the contact position in the bonding between the pad 12a and the lead 15 is detected by determining the difference between the command speed signal for driving the bonding arm 2 and the feedback speed signal from the encoder for counting the position of the bonding arm 2. Perform comparison. The encoder, the command speed signal, and the feedback speed signal from the encoder are referred to as position detecting means.

Before the ball 19 or the wire 18 at the tip of the capillary 2a abuts on the bonding point (descent at the search speed Vs), a command speed signal for driving the bonding arm 2 and a feedback speed signal from the encoder of the bonding arm 2 are provided. Is zero, but after the capillary 2a contacts the bonding point, the value of the feedback speed signal from the encoder becomes zero, and the difference between the command speed signal for driving the bonding arm 2 and the feedback speed signal from the encoder is obtained. Has increased, and it is determined that the difference has come into contact with the bonding point when the difference value is equal to or greater than a predetermined value. After detection of the contact position, bonding is performed by applying ultrasonic vibration to a predetermined bonding load and ultrasonic horn.

[0032]

As described above, the conventional wire bonding apparatus sets the search level S in order to absorb the variation in the height of the IC chip 12 and the variation in the height of the leads 15, and sets the search level. At the search speed Vs, the speed is reduced just before the level S, and the ball 19 or the wire 18 at the tip of the capillary 2a is brought into contact with the surface of the bonding point by the search speed Vs. .

However, the stop of the bonding arm 2 by the position detecting means is determined when the difference between the command speed signal for driving the bonding arm 2 and the feedback speed signal from the encoder is equal to or larger than a predetermined value. Therefore, it is determined that the contact has been made with respect to the bonding point, so that it is later than the actual contact point.

That is, in the conventional wire bonding apparatus, even if the search speed Vs is sufficiently reduced, detection by the position detecting means is performed after the capillary 2a actually contacts the pad 12a (or the lead 15) of the IC chip 12. To detect. Therefore, the detection of the contact position is delayed due to a variation in the height of the IC chip 12 or the like, and the impact force on the pad at the time of the contact increases due to the variation in the height and the amount of deformation of the ball 19. There is a possibility that the bonding load and the application timing of the ultrasonic power are not constant, the ball pressure diameter, the bonding strength and the like are changed, and the reliability of bonding is reduced.

The ball 19 at the tip of the capillary 2a
Alternatively, there is a problem that the moving time from the search level S to the contact with the pad 12a is several tens of msec, and the detection of the contact position is delayed by several msec after the actual contact.

If the distance from the search level S to the bonding point is lengthened, or if the position detection by the position detecting means is delayed, such a time delay accounts for a large proportion of the entire bonding time, thereby reducing the bonding time. There is a problem that it is difficult to plan.

An object of the present invention is to calculate the distance to each bonding point by measuring the distance between an IC chip and a lead from a predetermined reference position in a direction orthogonal to a plane where relative movement is performed before bonding. It is another object of the present invention to provide a wire bonding apparatus capable of performing high-speed and uniform bonding by controlling the operation of a bonding arm based on the calculated distance information.

[0038]

According to the present invention, there is provided a wire bonding apparatus comprising: a bonding means for performing bonding on a component to be bonded; and a positioning means for performing relative positioning two-dimensionally with respect to the component to be bonded. And imaging means mounted on the positioning means and imaging at least the part to be bonded,
Measuring means for obtaining distance information from a predetermined reference position to a component to be bonded placed on a bonding stage in a direction orthogonal to the plane on which the relative movement is performed; and bonding each of the components to be bonded based on the distance information. A calculation control means for calculating a distance to a point, and controlling the bonding means based on the calculated distance to each bonding point of the component to be bonded.

Further, the component to be bonded of the wire bonding apparatus according to the present invention is an IC chip, and distance information of at least three different positions of the IC chip is obtained by the measuring means. The distance to each bonding point is calculated by the arithmetic and control unit based on the calculated value, and the bonding is controlled by controlling the bonding means.

Further, the bonding means of the wire bonding apparatus according to the present invention has at least a bonding arm and a capillary, and the arithmetic control means controls the bonding arm to the bonding point based on distance information to each bonding point. The contact is controlled.

Further, a search level is set based on distance information to each of the bonding points of the wire bonding apparatus according to the present invention to control the bonding arm.

Further, the measuring means of the wire bonding apparatus according to the present invention includes at least a semiconductor laser as a light emitting means, a driving circuit for driving the semiconductor laser, and a light source for focusing laser light emitted from the semiconductor laser. An optical lens, a light position detecting element as a light receiving means, and a light receiving lens for focusing incident light on the light position detecting element,
And an amplifier for amplifying the output of the light position detecting element.

[0043]

Next, an embodiment of a wire bonding apparatus according to the present invention will be described with reference to the accompanying drawings. However, the wire bonding apparatus according to the present invention has substantially the same configuration and function as the conventional wire bonding apparatus shown in FIGS. 7 to 11 except for the parts described below. Therefore, description of the configuration and operation of the entire apparatus is omitted because it is redundant, and only the main part will be described. In the following description and drawings, the same or corresponding parts as those in the related art are denoted by the same reference numerals.

As shown in FIG. 1, this wire bonding apparatus has the same configuration as that of the conventional wire bonding apparatus shown in FIG. The measuring means 20 is composed of, for example, a laser displacement sensor, and is provided with a bracket 21 provided on the XY table 4.
Is mounted and fixed together with the camera 1.

The measuring means 20 moves in the vertical direction (indicated by an arrow V), that is, the IC chip 12 and the lead frame L as the parts to be bonded.
In a direction perpendicular to a plane in which the bonding head moves in a two-dimensional direction with respect to the lead 15 of the ＼F (shown in FIGS. 8, 10 and 11), a bonding target is set from a predetermined reference position (described later). This is to obtain distance information up to.

As shown in FIG. 2, the measuring means 20 has a cylindrical or box-shaped case 25 in which a semiconductor laser 27 as a light emitting means and a driving circuit for driving the semiconductor laser 27 are provided. 29 and the semiconductor laser 27
Projection lens 31 for focusing laser light emitted from
And a light position detecting element 33 as light receiving means, and a light receiving lens 35 for focusing light incident on the light position detecting element 33 and the like.
And an amplifier 3 for amplifying the output of the light position detecting element 33
7 and an amplifier 38.

The light position detecting element 33 emits a signal in accordance with the direction and distance in which the surface 40 of the object to be measured (such as a bonding object) is separated from the reference position 41 for measurement. More specifically, the laser light emitted from the semiconductor laser 27 is reflected by the surface 40 and the reflected light is incident on the light position detecting element 33 to form a spot. Depending on which side in the A direction or the B direction is located, the light spot detection element 3
3 moves in the directions of A ′ and B ′. Further, the movement amount of the spot corresponds to the distance of the surface 40 with respect to the reference position 41. Therefore, the light position detecting element 33 emits an electric signal according to the moving direction and the moving amount of the spot.

The electric signal generated by the light position detecting element 33 is amplified by the amplifier 37 and the amplifier 38, converted into a digital signal through an A / D conversion circuit (not shown), and transmitted to the controller unit 10 as arithmetic control means. (See FIG. 1). The controller unit 10 as the arithmetic control means stores the distance information in a built-in memory (RAM), and performs various controls described later based on the stored information.

The measuring means 20 is used to measure the distance from the capillary 2 a at the tip of the bonding arm 2 to the surface 40 of the object to be measured (the bonding object such as the IC chip 12 or the lead 15 as a part to be bonded). Make the following settings.

That is, as shown in FIG. 1, the lead frame L / F having the IC chip 12 adhered to the bonding stage 5 is carried in by a transport means (not shown).

The measuring means 20 irradiates a laser beam emitted from the semiconductor laser 27 shown in FIG.
3 is amplified by an amplifier 37 and an amplifier 38 and converted by an A / D conversion circuit so that the level of an output signal of a digital signal becomes “0”.
Is moved in the vertical direction (indicated by the arrow V) to fix the position (setting of the reference position 41).

Next, the bonding arm 2 is lowered, and from the preset origin position of the bonding arm 2 until the ball 19 at the tip of the capillary 2a contacts the same location on the surface of the IC chip 12 irradiated with the laser beam. The distance (L1) is counted by an encoder that detects the position of the bonding arm 2 and stored in a memory (RAM) in the controller unit 10 as arithmetic and control means. This setting need only be performed once when the bonding target type is replaced.

Thereafter, the distance (L) from the capillary 2a to the surface 40 to be measured becomes (L = L1 + K · Vd) when the level of the output signal from the measuring means 20 is Vd. Here, K is a coefficient for converting the level of the output signal from the measuring means 20 into a distance. Vd outputs a + (plus) sign when the surface of the measurement target is located in the B direction from the reference position 41 in FIG. 2, and −Vd when the surface of the measurement target is located in the A direction from the reference position in FIG. 2. Outputs (minus) sign.

FIG. 2 shows a reference position 41 of the measuring means 20 and a surface 40 to be measured (in FIG.
Of the capillary 2a until the ball 19 at the tip of the capillary 2a comes into contact.
3 shows the relationship between the distance (L1) from the origin position, the distance (K · Vd) based on the output signal level Vd from the measuring means 20, and the distance (L) from the capillary 2a to the surface 40 to be measured.

Next, a method of measuring the distance to the bonding point using the measuring means 20 will be described.

First, as shown in FIGS. 1 and 10, before the wire bonding, the IC chip 12 is imaged by the camera 1 as an image pickup means, and the image recognition signal is used by the image recognition unit 8 to determine the reference of the regular IC chip 12 '. From the actual IC chip 12 position is calculated from the actual IC chip 12 position.
The position of the chip 12 is detected (IC chip position detection).

Similarly, the image of the lead 15 side is taken by the camera 1, and the image recognition unit 8 determines the reference position of the regular lead 15 and the actual lead 15 from the image signal.
Of the lead 15 is detected, and the actual bonding position of the lead 15 is detected (lead position detection).

When the number of the leads 15 is large, the width of the leads, and the pitch between the leads are narrow, a lead locator (images of the individual leads 15 are taken and the position of the bonding point of each lead 15 is detected by the image recognition unit 8). May be used to detect the bonding position of each lead 15.

The bonding position and the like are represented by XY coordinates on an XY table 4 which is moved and positioned two-dimensionally in the X and Y directions. The position of the bonding arm 2 which is a direction orthogonal to the plane on which the movement of the XY table 4 is performed is represented by Z coordinates.

Next, a predetermined IC chip 12
The position coordinates of the three different points are calculated from the shift amounts obtained by detecting the position of the IC chip 12 to obtain the position coordinates of the three points. For the positions of the three points, a pad which is a bonding point may be selected. The detection of the coordinates of these three points is performed by the IC chip 12.
Can be obtained, so three or more points may be obtained.

The position coordinates of the three points are as shown in FIG.
(X1, Y1), (X2, Y2), (X
3, Y3). The IC chip 12 has a square shape or a rectangular shape, and the surface and the like of the IC chip 12 are designed with high accuracy. Therefore, the position coordinates of the three points are determined by the IC chip 1 in order to secure the accuracy of the distance data.
It is desirable to specify one of the four corners above 2, but it may be another location.

Next, the measuring means 20 mounted on the XY table 4 is moved to the position coordinates (X1, Y1). X
After stopping the Y table 4, the measuring means 20 performs length measurement at the position coordinates (X1, Y1).

Assuming that the output level from the measuring means 20 is V1, the distance (Z1) from the ball 19 at the tip of the capillary 2a to the position coordinates (X1, Y1) on the IC chip 12
Is Z1 = L1 + K · V1.

Similarly, the other two points (X2, Y2), (X3,
The length is also measured in Y3), and the respective distances are set to Z2 and Z3.

As shown in FIG. 3, the position coordinates of the three points on the X, Y, Z coordinates are (X1, Y1, Z1), (X
2, Y2, Z2) and (X3, Y3, Z3).

The surface of the IC chip 12 can be regarded as a flat surface, and three points (X1, Y1, Z1), (X2, Y2, Z
2) The equation of a plane including (X3, Y3, Z3) is represented by the following determinant.

[0067]

(Equation 1)

By expanding the above determinant, three points (X1, Y1,
Z1), (X2, Y2, Z2), (X3, Y3, Z3)
Are substituted to obtain a linear equation of plane AX + BY + CZ + D = 0 (2). Here, A, B, C, and D are coefficients.

The above calculation is executed by a microcomputer built in the controller unit 10 as operation control means.

Next, the position coordinates of the pad 12a on the IC chip 12, which is the first bonding point, is calculated from the amount of displacement of the IC chip 12. The calculated values of X and Y are substituted into equation (1) to determine the value of Z.

The values of X and Y represent the position coordinates of the pad for performing wire bonding, and the value of Z represents the distance from the ball 19 at the tip of the capillary 2a at the origin position of the bonding arm 2 to the surface of the pad 12a.

By substituting the XY position coordinates of the pad 12a to be bonded into the equation (1), the value of Z (Z position coordinate) can be obtained, and it is not necessary to measure the distance on all the pads 12a.

Next, measurement of the distance to the bonding point on the lead side will be described.

The distance measurement of the lead 15 is performed by using XY coordinates on the bonding position coordinates of the lead 15 in the lead position detecting step.
The table is stopped, and the length is measured by the measuring means 20 at that position.

The distance (L) from the tip of the capillary 2a at the origin position of the bonding arm 2 to the surface of the lead to be measured is represented by the level of the output signal from the measuring means 20 (L = L1 + K · Ve). ). The XY table is similarly moved and measured for the other leads 15, and the distance to the surface of each lead 15 (shown in FIGS. 8, 10, and 11) is calculated.

Here, L1 is the distance from the reference position 41 to the reference position when the ball 19 is located at the tip of the capillary 2a. When bonding the lead 15, the tip of the capillary 2a becomes the wire 18. Therefore, the difference (e in FIG. 4) between the length from the tip of the capillary 2a to the tip of the ball 19 (b in FIG. 4) and the length from the tip of the capillary 2a to the surface of the wire 18 (w in FIG. 4). A memory (RAM) as storage means of the controller unit 10
Set to.

The difference (e in FIG. 4) is added to L1 as offset data, and the added data (L1 + e) is used as the distance (L1) from the origin position of the bonding arm 2 at the time of lead bonding.

Next, the operation of the wire bonding apparatus according to the present invention will be described.

First, the capillary 2a is positioned on the XY table 4 immediately above the pad 12a, which is the first bonding point.

Next, the bonding arm 2 is moved from the tip of the capillary 2a to the surface of the pad 12a (Z of the pad 12a).
The following control is performed based on the distance to the position coordinates. That is, a command signal for lowering the bonding arm 2 to the Z position coordinate is issued from the controller unit 10 to the drive unit 11, and the bonding arm 2 is lowered to the Z position coordinate and stopped. FIG. 5 shows a descending speed waveform of the bonding arm 2 at this time. The bonding arm 2 descends at a high speed and stops while decelerating. FIG. 6A shows a state in which the ball 19 contacts the pad 12a when the bonding arm 2 is stopped.

In the conventional wire bonding apparatus, the ball 19 at the tip of the capillary 2a comes into contact with the pad 12a at a constant speed (search speed Vs), so that an impact force is generated and the initial deformation of the ball 19 (FIG. 6 (b)) occurs. Was happening. In the present invention, the speed at which the ball 19 at the tip of the capillary 2a contacts the pad 12a is almost zero, so that no impact force is generated and no initial deformation of the ball 19 occurs. In other words, in the wire bonding apparatus according to the present invention, as shown in FIG. 2, the distance L between the capillary 2a and the bonding point can be accurately obtained by the measuring means 20. It is not necessary to decelerate and change from the search level S to the search speed Vs, and the search level S may be set as a position for switching from high speed to low speed. Therefore, the search level S can be set close to the bonding point. Thus, in the embodiment according to the present invention, as shown in FIG. 5, the search level S is not set, and the vehicle stops at the bonding point while decelerating.

Next, after the bonding arm 2 stops, a bonding load is applied to the bonding arm 2 and an ultrasonic vibration is applied to the ultrasonic horn. The pressure bonding diameter of the ball 19 is determined by the bonding load, the magnitude of the ultrasonic vibration (power), and the application time, so that stable bonding can be performed.

After bonding to the pads of the IC chip 12, the capillary 2a is raised according to a predetermined loop control and moved in the lead direction, which is the second bonding point.

Next, the capillary 2a is descended at a high speed and stopped at the lead surface (lead Z position coordinates) while decelerating. After the bonding arm 2 is stopped, a bonding load is applied and an ultrasonic vibration is applied to the ultrasonic horn to connect the wire 18 to the lead 15. Also on this lead side, the search level S is not set, and is stopped while decelerating.

Thereafter, the capillary 2a is raised, the wire 18 is projected to a predetermined length at the tip of the capillary 2a, and the wire cut clamp 14 is closed at a preset rising position of the capillary 2a, and the wire 18 on the lead 15 is cut. Then, the wire 18 is extended to the tip of the capillary 2a by a predetermined length (amount of wire feed).

As described above, the wire bonding apparatus according to the present invention does not need to apply the load and the ultrasonic vibration after the detection of the bonding point contact position, unlike the conventional wire bonding apparatus.
Immediately after descending to the bonding point, the application of the bonding load and the application of the ultrasonic vibration are performed, so that the bonding can always be performed under the same conditions without being affected by the delay or variation in the detection of the contact position at the bonding point.

Further, a search level is set for each bonding point based on information on the distance to the bonding surface, and a bonding operation similar to that of a conventional wire bonding apparatus can be performed. At this time, the search level S can be set near the bonding surface (for example, at a position of 40 μm from the bonding surface) because the distance to the bonding surface is already known, so that the bonding time can be reduced.

[0088]

As described above, the wire bonding apparatus according to the present invention measures the distance between an IC chip and a lead from a predetermined reference position in a direction perpendicular to a plane on which relative movement is performed before bonding. By calculating the distance to each bonding point and controlling the operation of the bonding arm based on the calculated distance information, it is not necessary to detect the contact position at the bonding point, thereby reducing the bonding time. Can be.

Further, the wire bonding apparatus according to the present invention provides a ball with initial deformation failure due to a search operation, a variation in initial deformation, a load application based on detection of a contact position, a ball crimping diameter due to a delay in application of ultrasonic vibration, and bonding. Since no change in strength or the like occurs, the quality of bonding can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a wire bonding apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration of a measuring unit of the wire bonding apparatus shown in FIG.

FIG. 3 is a diagram showing position coordinates of three points serving as measurement points on X, Y, and Z coordinates.

FIG. 4 is a diagram illustrating the length from the tip of the capillary to the tip of the ball and the length from the tip of the capillary to the surface of the wire.

FIG. 5 is a diagram showing a descending speed waveform of a bonding arm according to the present invention.

FIG. 6A shows a state in which a ball abuts on a pad when the bonding arm according to the present invention is stopped, and FIG.
FIG. 4 is a view showing a state (initial deformation) of a ball in contact with a pad when a bonding arm of a conventional wire bonding apparatus is stopped.

FIG. 7 is a diagram illustrating a configuration of a conventional wire bonding apparatus.

FIG. 8 is a diagram showing a tool height and a search level in a conventional wire bonding apparatus.

9A is a diagram illustrating a velocity waveform when the bonding arm of the conventional wire bonding apparatus is lowered, and FIG. 9B is a diagram illustrating a locus when the bonding arm is lowered.

FIG. 10 is a diagram showing a position of an IC chip attached to a lead frame, and a dotted line shows a position of a regular IC chip to be attached.

FIGS. 11A to 11D are views including a partial cross section for explaining a wire bonding step.

[Explanation of symbols]

 L＼F Lead frame 1 Camera (imaging means) 2 Bonding arm 2a Capillary 4 XY table (positioning means) 8 Image recognition unit 10 Controller unit 11 Drive unit 12 IC chip 12a Pad (of IC chip 12) 14 Wire cut clamp 15 Lead Reference Signs List 16 discharge electrode 18 wire 19 ball 20 measuring means 27 semiconductor laser (light emitting means) 29 drive circuit 33 optical position detecting element (light receiving means)

Claims (5)

[Claims] 1. A bonding means for performing bonding on a part to be bonded, a positioning means for performing relative movement two-dimensionally with respect to the part to be bonded, and positioning, and at least the mounting means mounted on the positioning means. Imaging means for imaging the part to be bonded; measuring means for obtaining distance information from a predetermined reference position to the part to be bonded arranged on a bonding stage in a direction orthogonal to the plane on which the relative movement is performed; Calculation control means for calculating a distance to each bonding point of the component to be bonded based on the distance information, and controlling the bonding means based on the calculated distance to each bonding point of the component to be bonded. Characteristic wire bonding equipment. 2. The part to be bonded is an IC chip, and distance information of at least three different positions of the IC chip is obtained by the measuring means, and the arithmetic control means based on the obtained distance information. The wire bonding apparatus according to claim 1, wherein the bonding is performed by calculating a distance to each bonding point and controlling the bonding means. 3. The bonding means has at least a bonding arm and a capillary, and the arithmetic control means controls the contact of the bonding arm to the bonding point based on distance information to each bonding point. The wire bonding apparatus according to claim 2, wherein: 4. The control of the bonding arm according to claim 2, wherein a search level is set based on distance information to each of the bonding points.
The wire bonding apparatus as described in the above. 5. The measuring means includes at least a semiconductor laser as a light emitting means, a drive circuit for driving the semiconductor laser, a light projecting lens for focusing laser light emitted from the semiconductor laser, and a light receiving means as a light receiving means. 2. The wire according to claim 1, further comprising: a light position detecting element, a light receiving lens for focusing light incident on the light position detecting element, and an amplifier for amplifying an output of the light position detecting element. Bonding equipment.