JPH10247660A - Bonding method and bonding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable bonding characteristic because a conventional bonding method is affected by a mounting accuracy of semiconductor pellets and a bonding order. Further, since the distance between the connection point and the reference position is measured for each bonding, the bonding processing time becomes long. SOLUTION: While bonding is performed with respect to connection points 30 of No. 1b and No. 1n, distances L ₁ and L _n between the two connection points and a reference position 6 are measured, and based on the measured distances between the two points. , No. 2b and the distance from the reference position 6 at the remaining connection points are calculated. Then, for the remaining connection points, for example, the connection point of No. 2b,
Of the value H ₂ obtained by subtracting the distance S of the search section from the known distance L ₂ at the connection point, by changing the distance of the high speed section in the bonding operation for the connection points of Nanba2b, they were divided into high-speed section and search section Bonding is performed at a two-step lowering speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a bonding method, and more particularly to a bonding method of a bonding apparatus for automatically connecting a wire to each connection point on a semiconductor pellet attached to a substrate by a bonding tool.

[0002]

2. Description of the Related Art Conventionally, as a bonding method of this kind, for example, as shown in JP-A-63-136535, a good bonding characteristic is obtained in a bonding apparatus even when a semiconductor pellet is attached at an angle. Known for the purpose. Hereinafter, such a conventional example will be described with reference to the drawings.

FIG. 3 is a schematic view showing a state of a semiconductor pellet and a bonding tool in a bonding step which is one of semiconductor manufacturing steps. FIG. 4A is a schematic view showing a positional relationship between the bonding tool and the semiconductor pellet. FIG.
(B) is a timing chart showing the movement locus of the bonding tool.

[0004] As shown in FIG. 3, a bonding process is performed by a semiconductor pellet 3 attached on a substrate 1 with an adhesive 2 or the like.
This is a step of connecting each of the electrodes and each lead terminal 4 provided on the substrate 1 with a thin wire 5. Usually, a bonding tool 7 for performing bonding is located above the substrate 1 at a reference position 6 which is separated by a predetermined distance L.

As shown in FIG. 4, the distance L from the reference position 6 to the connection point of the semiconductor pellet 3 is divided into a high-speed section (distance H) and a search section (distance S). When the bonding tool 7 is lowered to the connection point of the semiconductor pellet 3, the bonding tool 7 is lowered at a high speed in the high-speed section, and is lowered at a lower speed in the search section than in the high-speed section.

Next, the operation of the bonding tool in the conventional process will be specifically described with reference to FIGS. 5A is a top view of a semiconductor pellet to be bonded, FIG. 5B is a side view of FIG. 5A, and FIG. 6 is a tool when adjacent connection points are sequentially bonded by a conventional bonding method. It is a figure which shows operation | movement.

As shown in FIG. 5, for example, there are connection points No. 1b to No. nb on the side b of the semiconductor pellet 3,
The distance between the connection points 30 and the reference distance 6 is assumed to be changed from L ₁ to L _n.

First, the distance H _{1 in} the high-speed section and the distance S _{1 in the} search section at the start of bonding are input from an operation panel or the like by an operator in advance for each type of semiconductor pellet 3 to be bonded.

[0009] Initialization is completed, descends at high speed by a distance H ₁ in the high speed section to the bonding tool 7 is set in advance, changes at a constant speed of the low speed at the lower end position of the high speed section. Next, descends the slow speed by a distance S ₁ of the search section. Then, at the time of contact with the connection point 30, the distance L ₁ between the reference position 6 and the connection point 30 it is measured.

Next, the connection point 30 of the adjacent No. 2b is
The bonding operation to be performed is started. In this case, No. 2b
Distance H of the high-speed section of the connection point 30_TwoIs the connection point of No.1b
Preset from the distance L measured during the bonding operation of
Search section distance S ₁(The previous distance)
Release L₁-Search section S₁). And this
Distance H_TwoAt the high speed section
Lower from the end position at low speed. Bonding tool 7
Contacts the connection point 30 of No. 2b,
Distance L between connecting point 30 and reference position 6_TwoIs measured.

As described above, each time the bonding operation at one connection point 30 is performed, the current connection point 3
The distance L between 0 and the reference position 6 is measured, and the high-speed section H of the bonding operation at the next adjacent connection point is corrected from the distance L. As a result, the maximum error of the actual distance S in the search section in which the bonding tool descends at a low speed is suppressed within the difference between the previous distance L and the current distance L. As a result, the actual distance S of the search section at each connection point 30 hardly changes from the preset distance S. The bonding tool always comes into contact with each connection point 30 under almost constant conditions, and stable bonding characteristics can be obtained.

[0012]

However, the above-mentioned conventional bonding method has the following problems. FIG. 7 is a diagram for explaining a problem in the conventional bonding method.

A first problem is that when bonding non-adjacent connection points sequentially, a stable bonding characteristic cannot be obtained even if the distance H in the high-speed section is sequentially corrected. That is, for example, when the order of the connection points to be bonded on the side b of the semiconductor pellet 3 shown in FIG. 5B is No. 1b, No. nb, No. 2b,. As shown, the distance H _n (= L ₁ −S ₁ ) of the high-speed section at the next connection point of No. nb is calculated from the distance L ₁ between the connection point of No. 1b and the reference position. As a result, the actual distance is next S _n of the search section in No.Nb, the maximum error between the search section S ₁ which is preset L ₁ -
L _n . As described above, since the actual distance S in the search section changes at the connection point between No. 1b and No. nb, stable bonding characteristics cannot be obtained.

The second problem is that the time from the start to the end of bonding becomes long. That is, since the distance between the reference position and the connection point of the semiconductor pellet is measured every time the bonding operation is performed, the processing time at each connection point becomes longer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bonding method and apparatus for performing a stable bonding operation without being affected by the mounting accuracy of semiconductor pellets and the bonding order in view of the above-mentioned problems of the prior art. It is in. It is a further object of the present invention to provide a bonding method and apparatus for performing a faster bonding process.

[0016]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a method in which a distance from a reference position above a semiconductor pellet having a plurality of connection points on an upper surface to the connection point is defined as an upper high-speed section. By dividing the bonding tool into a lower search section and lowering the bonding tool at a high speed in the high-speed section, and lowering the bonding tool at a lower speed than the high-speed section in the search section, and contacting the connection point, In a bonding method in which bonding is performed in a predetermined order at each connection point, before performing bonding at a two-step descending speed divided into the high-speed section and the search section, the distance between the reference position and the search section is determined. The distances from the reference position at the two or more connection points are measured while performing bonding at the two or more connection points. The distance from each of the two or more points to the reference position at each connection point is calculated in advance, and then, for the remaining connection points, the two-step descending speed divided into the high-speed section and the search section And sequentially changing the distance of the high-speed section for each bonding to a value obtained by subtracting the distance of the search section from the known distance from the reference position at the connection point to be bonded.

In order to implement such a bonding method,
Contact detection means for detecting contact between the connection point on the semiconductor pellet and the bonding tool, position measurement means for measuring a distance from a reference position of the bonding tool to the connection point when the contact detection means detects contact, A bonding apparatus comprising: distance calculating means for calculating the distance from each of the connection points to the reference position from the distance from the reference position at two or more connection points measured by the position measurement means.

In the invention as described above, the distances to the reference positions at each connection point are calculated from the distances to the reference positions at two or more connection points measured while bonding in advance. Thereafter, for the remaining connection points not used in the calculation of the distance between the reference position and the connection point, the connection to be bonded is determined based on the known distance between the reference point and the search section at the connection point to be bonded. While correcting the distance of the high-speed section in the bonding operation with respect to the point, bonding is sequentially performed at two stages of descending speed divided into the high-speed section and the search section.

Thus, when the semiconductor pellet is mounted obliquely, a constant search section can be secured without successively bonding adjacent connection points, and thus stable bonding characteristics can be obtained. That is, in the related art, the high-speed section at the time of the current bonding is calculated using the distance from the reference position at the connection point of the previous bonding. Therefore, if the difference in distance between the connection point and the reference position before and after bonding is large,
In some cases, the actual distance in the search section also changed significantly. However, in the present invention, a value obtained by subtracting the distance of the preset search section from the distance from the reference position at the current connection point is set as the distance of the high-speed section at the time of bonding this time. The actual distance is constant without changing from the set value.

Further, since it is not necessary to calculate the distance between the connection point and the reference position every time the bonding operation is performed, a higher-speed bonding process can be performed.

[0021]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a schematic view of a bonding apparatus to which the bonding method of the present invention is applied. In this figure, the same components as those of the prior art shown in FIGS. 3 to 7 are denoted by the same reference numerals.

In FIG. 1, the stator 12a of the linear motor 12 is mounted on the fixed eleventh. Stator 1
2a and the movable coil 12b, the linear motor 12
An exciting current is supplied from the moving motor control unit 21 to the movable coil 12b, and the direction of the current changes, so that the movable coil 12b moves up and down.

The movable coil 12b of the linear motor 12
It is fixed to the lower surface of the movable arm 14. That is, when the linear motor 12 moves up and down, the movable arm 14 also moves up and down at the same time. The stator 13a of the linear motor 13 for pressurization is attached to the movable arm 14.
The movable coil 13b of the linear motor 13 is fixed to the tool support 15. The linear motor 13 including the stator 13a and the movable coil 13b is supplied with an exciting current from the pressurizing motor control unit 20 to the movable coil 13b, and the direction of the current is changed.
b moves up and down. As a result, the tool support 15 to which the movable coil 13b is attached moves up and down, and the tool arm 16 attached to the tool support 15 and the bonding tool 7 attached to the tip of the tool arm 16 also move up and down.

The tool support 1 of the movable arm 14
A gap sensor 18 is attached to a side end of the fifth sensor 5. When the distance between the gap sensor 18 and the tool support unit 15 changes, the gap sensor 18 generates a voltage corresponding to the amount of change and sends it to the A / D conversion unit 19.
That is, when the movable arm 14 moves down, the bonding tool 7 contacts the connection point of the semiconductor pellet 3 and the tool arm 16 moves up, the gap sensor 18 outputs a contact signal. The contact signal is converted into a digital value by the A / D converter 19 and input to the bonding controller 23. Note that the gap sensor 18 and the A / D converter 19 correspond to a contact detection unit according to the present invention. When a contact signal is input from the gap sensor 18 via the A / D converter 19, the bonding controller 23 outputs a drive signal to the pressure motor controller 20. Upon receiving the drive signal, the pressurizing motor control unit 20 operates the linear motor 13 in a direction in which the bonding tool 7 is further pressed against the connection point of the semiconductor pellet.

A non-contact distance sensor 17 for detecting a distance between the movable arm 14 and the fixed base 11 is attached to an end of the movable arm 14 opposite to the tool support 15. The distance signal detected by the non-contact distance sensor 17 is input to the position detection control unit 22. Note that the non-contact distance sensor 17 and the position detection control unit 22 correspond to a distance measuring unit according to the present invention. The position detection control unit 22 outputs a drive signal to the moving motor control unit 21 according to the control signal sent from the bonding control unit 23 and the distance signal. Upon receiving the drive signal, the moving motor control unit 21
The linear motor 12 is controlled in accordance with the drive signal, and the vertical position of the movable arm 14 is controlled. Further, the position calculation unit 24, which is a distance calculation unit according to the present invention, uses the distance signal detected by the position detection control unit 22 to calculate each connection point 30.
Calculate the distance of

Next, a bonding method using the bonding apparatus shown in FIG. 1 will be described with reference to FIG. FIG. 2 is a diagram showing the operation of the bonding tool according to the bonding method of the present invention. Also in this figure, FIGS.
The same components as those of the prior art shown in FIG.

Here, for example, FIGS. 5A and 5B
When connecting n connection points on the side b of the semiconductor pellet 3 attached to the substrate 1 in an inclined state as shown in FIG. 1, in the order of No. 1b, No. nb, No. 2b,. Assume bonding.

First, before starting the bonding operation,
The operator has the reference position 6 where the search section can be absolutely secured.
And a search section (distance S) are set in the bonding control unit 23 from a keyboard or the like of an operation panel (not shown).

When the initial setting is completed, the bonding control unit 23 drives the linear motor 12 via the position detection control unit 22 and the moving motor control unit 21 so that the bonding tool 7 moves to the reference position 6.

First two connection points (No. 1b, No. nb)
Since the distance L between the connection point 30 and the reference position 6 is unknown, the bonding control unit 23 outputs a control command so that bonding is performed at a low speed from the reference position 6. Bonding tool 7 descending at low speed is N
When contact is made with the connection point 30 of o.1b, the gap sensor 18
Operates, and a contact signal is input to the bonding control unit 23 via the A / D conversion unit 19. Bonding control unit 2
3 sends a drive signal to the pressurizing motor control unit 20 when a contact signal is input, and sends a control command to the position detection control unit 22 to send a distance L between the reference position 6 and the connection point 30 at this time. ₁ is read from the non-contact distance sensor 17.

When the connection operation is completed, the bonding controller 23 drives the linear motors 12 and 13 via the respective controllers so that the bonding tool 7 moves to the reference position 6 again.

The same processing as described above is performed for the second connection point of No. nb, and the distance L _n between the reference position 6 and the connection point of No. nb
To get. The distance L of each connection point is calculated by the position calculation unit 24 using the distance L acquired here, that is, interpolation is performed. For example, assuming that the distances L between the connection points 30 of No. 1b and No. nb and the reference position 6 are L ₁ and L _n , respectively, and that the distance between the connection points is equal, the connection to be bonded to the third and subsequent connections distance L _x of the point No.xb can be obtained by the following equation.

[0034]

L _x = L ₁ + (x−1) × (L ₁ −L _n ) / (n−1) Therefore, in the bonding operation to the third and subsequent connection points, the distance obtained by the above expression from L _x, it is possible to calculate the distance of the high speed section _{H x (= L x -S)} . Then, during a high-speed section (distance H _x ) from the reference position 6, the bonding tool 7 is moved at a high speed, and thereafter, a search section (distance S) is moved at a low speed to bring the bonding tool 7 into contact with the connection point. When the connection operation is completed, the bonding control unit 23 controls the linear motor 12 via each control unit so that the bonding tool 7 moves to the reference position 6 again.
And 13 are driven.

[Other Embodiments] Next, a bonding method according to another embodiment of the present invention will be described with reference to the drawings.

Here, for example, FIGS. 5A and 5B
No. 1a, No. 1b, No. 1 when connecting n connection points on each side of a to d of the semiconductor pellet 3 attached in an inclined state to the substrate 1 as shown in FIG.
Assume that bonding is performed in the order of c, No. 1d,.

The bonding operation is performed at a low speed from the reference position 6 to the third connection point No. 1c.
And the distance L between the point and the connection point 30 are read. The plane of the semiconductor pellet is calculated from the distances L ₁ a, L ₁ b, and L ₁ c of the three points thus obtained, and the distance Lx between each connection point x and the reference position is obtained.

In the fourth and subsequent bonding operations, the bonding operation is sequentially performed at two stages of speed while correcting the distance H _x (= L _x −S) in the high-speed section by the obtained distance L _x .

[0039]

As described above, according to the present invention, the distance between the reference position at each connection point and the reference position at each connection point is calculated in advance from the distance between the measured two or more connection points and the reference position. , A certain search section can be secured.
As a result, stable bonding characteristics can be obtained regardless of the order of connection points to be bonded, even when the semiconductor pellet is attached at an angle.

Further, at the time of the bonding operation of the connection point not used for calculating the distance between the connection point and the reference position,
Since it is not necessary to calculate the distance between the reference position and the connection point every time bonding is performed, the processing time for bonding can be reduced as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a bonding apparatus to which a bonding method of the present invention is applied.

FIG. 2 is a diagram showing an operation of a bonding tool according to the bonding method of the present invention.

FIG. 3 is a schematic view showing a state of a general semiconductor pellet as a bonding target and a bonding tool.

FIG. 4A is a schematic diagram illustrating a positional relationship between a bonding tool and a semiconductor pellet, and FIG. 4B is a timing chart illustrating a movement locus of the bonding tool.

FIG. 5A is a top view of a semiconductor pellet to be bonded, and FIG. 5B is a side view of FIG.

FIG. 6 is a diagram showing an operation of a tool when adjacent connection points are sequentially bonded by a conventional bonding method.

FIG. 7 is a diagram for describing a problem in the conventional bonding method, and is a diagram illustrating an operation of a tool when non-adjacent connection points are sequentially bonded.

[Explanation of symbols]

 Reference Signs List 3 semiconductor pellet 7 bonding tool 11 fixed base 12, 13 linear motor 12a, 13a stator 12b, 13b movable coil 14 movable arm 15 tool support section 16 tool arm 17 non-contact distance sensor 18 gap sensor 19 A / D conversion section 20 addition Pressure motor control unit 21 Moving motor control unit 22 Position detection control unit 23 Bonding control unit 24 Position calculation unit

Claims (2)

[Claims] 1. A distance from a reference position above a semiconductor pellet having a plurality of connection points on an upper surface to the connection point is divided into an upper high-speed section and a lower search section, and the bonding tool is provided. A bonding method in which bonding is performed in a predetermined order at each of the connection points by lowering at a higher speed in the high-speed section and lowering in the search section at a lower speed than the high-speed section and contacting the connection points. Before performing bonding at a two-step descending speed divided into the high-speed section and the search section, the distance between the reference position and the search section is set, and bonding is performed for two or more connection points. The distance to the reference position at each of the two or more connection points is measured, and the reference distance at each of the connection points is measured based on the measured distances of the two or more points. Then, bonding is performed sequentially at two stages of descending speeds divided into the high-speed section and the search section for the remaining connection points. A bonding method, wherein a distance is changed to a value obtained by subtracting a distance of the search section from a distance from the known reference position at a connection point to be bonded. 2. A bonding apparatus used for carrying out the bonding method according to claim 1, wherein a contact detecting means for detecting a contact between a connection point on the semiconductor pellet and a bonding tool, and a contact detection of the contact detecting means. A position measuring means for measuring a distance from a reference position of the bonding tool to the connection point, and a distance between the reference positions at two or more connection points measured by the position measurement means. And a distance calculating means for calculating a distance from the position.