JPH02146742A - Method and device for wire bonding - Google Patents

Abstract

PURPOSE:To secure reliability of a junction at a side section of an insulating coated wire and a second position by making discharge through an insulating coat between a core and a discharge electrode at a section whereon junction with the second position is scheduled and by forming an exposed section of the core by eliminating the insulating coat by discharge energy. CONSTITUTION:A tip section of an insulating coated wire 13 which is inserted to a bonding tool 10 is joined to a first position 3a, a side section of the insulating coated wire 13 which is drawn out from the bonding tool 10 is joined to a second position 4b, and the first position 3a and the second position 4b are electrically connected. In such a case, the insulating coated wire 13 is drawn out from the tip section of the bonding tool 10 by a desired length which is calculated based on position information of the first and the second positions 3a, 3b. Discharge is made through an insulating coat 13b between the core 13a of the insulating coated wire 13 and a discharge electrode 160 at a section whereon a junction is scheduled with the second position 4b, and the insulating coat 13b is eliminated by the discharge energy produced at that time to form an exposed section 13d of the cable. The exposed section 13d is joined to the second position 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to wire bonding technology, and particularly to a technology that is effective when applied to a wire bonding process in the assembly of semiconductor integrated circuit devices using insulated wires.

[Conventional technology]

For example, in the assembly process in the manufacture of semiconductor integrated circuit devices, a plurality of external connection electrodes provided on a semiconductor pellet on which a predetermined integrated circuit is formed are connected to a plurality of leads that function as external connection terminals during mounting. As a method, a wire bonding technique is known in which a conducting wire is installed between the two and connected individually.

On the other hand, in response to recent demands for higher integration and miniaturization of semiconductor integrated circuit devices, the density of external connection electrodes to be connected has been increasing dramatically, and as a result, the density of bonding wires has increased dramatically. As the spacing and wire diameter continue to become smaller, it has become difficult to prevent short circuits between the bonding wires and to maintain the shape of each wire loop due to a decrease in the rigidity of the bonding wires.

In order to deal with this, for example, by using an insulated wire that has a core wire made of metal or the like coated with insulation,
It is possible to prevent short circuits and improve rigidity, but
For example, in the well-known pole bonding technology, in which the tip of a bonding wire inserted into a bonding tool such as a capillary is melted and formed into a ball shape, bonding is performed on the lead side using the side surface of the insulated wire. There is a concern that reliability of the bonding portion, which is performed by pressing the lead against the lead, may be reduced due to a reduction in bonding strength and an increase in electrical resistance.

For this reason, conventionally, for example, Japanese Patent Application Laid-Open No. 62-14042
Techniques disclosed in Japanese Patent Application No. 8 and Japanese Unexamined Patent Publication No. 61-104127 are known.

That is, the former conventional technology increases the pressing force of the bonding tool in multiple stages during the bonding operation to the lead side of the insulation-covered wire, thereby bonding the insulation coating interposed between the core wire of the insulation-covered wire and the lead. This aims to ensure the reliability of the joint by eliminating the material.

In addition, in the latter conventional technology, when bonding the insulated wire to the lead side, the core wire of the insulated wire is This aims to ensure the reliability of the joint by eliminating the insulating coating interposed between the lead and the lead.

[Problem to be solved by the invention]

However, in any of the above conventional techniques, when bonding the insulated wire to the lead side,
Although bonding is started with the insulation coating material still interposed in the bonding part, foreign matter caused by heat denaturation of the insulation coating material may remain between the core wire and the lead, causing the bonding at the bonding part. There is a problem in that it causes deterioration in strength and increase in electrical resistance, making it difficult to ensure reliability in wire bonding.

Furthermore, in each of the above-mentioned conventional techniques, bonding is performed with the insulation coating interposed between the core wire of the insulation-coated wire and the capillary, so that the insulation coating material and foreign matter peeled off from the wire due to bonding load or heating, etc. There is also the problem that it gets into the wire insertion part of the capillary, contaminates it, and obstructs the smooth feeding and drawing operations of the insulated wire, making it difficult to continue stable bonding operations.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a wire bonding technique that can ensure the reliability of the joint between the side surface of the insulated wire and the second position.

Another object of the present invention is to provide a wire bonding technique that prevents contamination of a bonding tool due to the insulation coating material constituting the insulation coating wire and enables stable continuation of bonding work.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the wire bonding method of the present invention uses an insulated wire inserted into a bonding tool, and includes an operation of bonding the tip of the insulated wire to a first position, and an operation of bonding the tip of the insulated wire to a first position, and an operation of bonding the tip of the insulated wire inserted into a bonding tool. A wire bonding method for electrically connecting a first position and a second position by performing an operation of joining a side surface of the first position to a second position, the wire bonding method comprising: Pull out the insulated wire from the tip of the bonding tool by the required length calculated based on the position information of
A discharge is caused to occur through the insulation coating between the core wire of the insulated wire and the discharge electrode at the site where it is to be joined to the second position, and the insulation coating is removed by the discharge energy at that time to expose the exposed portion of the core wire. , and this exposed portion is joined to the second position.

Further, the wire bonding device of the present invention generates electrical discharge at any time between the bonding tool, through which the insulated wire is inserted, and which is capable of three-dimensional displacement relative to the object, and the insulated wire. an operation of bonding the tip of the insulated wire, in which a ball has been formed by the discharge, to a first position; and a side part of the insulated wire fed out from the bonding tool to a second position. A wire bonding device that electrically connects the first position and the second position by performing an operation of Calculate the required length of the insulated wire to be installed at the second position, pull out the required length of the insulated wire from the tip of the bonding tool based on the calculation result, and plan to join it to the second position. A discharge is caused to occur between the core wire of the insulated wire and the discharge electrode at the site through the insulating coating, and the discharge energy at that time removes the insulating coating to form an exposed portion of the core wire. It is arranged to be joined at the second position.

[Effect]

According to the above-described wire bonding method of the present invention, prior to bonding the side surface portion of the insulated wire to the second position, the insulating coating of the part of the insulated wire to be bonded is removed to form an exposed portion of the core wire. Therefore, it is possible to perform the bonding operation while the core wire exposed from this exposed portion is in direct contact with the second position, and there is no insulating coating material between the core wire and the second position. Deterioration in the reliability of the joint due to the presence of such intervening parts is eliminated, and the reliability of the joint at the side surface of the insulated wire and the second position can be ensured.

In addition, since there is no insulation coating between the core wire and the second position, the amount of foreign matter generated due to insulation coating peeling or thermal denaturation is greatly reduced, and the bonding tool Since the core wire of the insulated wire exposed from the part is directly pressed, foreign matter will not get into the bonding tool, ensuring smooth insertion of the insulated wire into the bonding tool, and stabilizing the bonding work. Continuation is possible.

Further, according to the wire bonding apparatus of the present invention,
For example, by appropriately controlling the first and second wire clampers that operate independently to control the feeding of the insulated wire from the bonding tool, the second wire clamper at a desired distance from the tip of the insulated wire can be Prior to joining the side portion of the insulated wire to the second position, the insulation coating can be removed to form an exposed part of the core wire at the site where the wire is to be joined to the second position, and the core exposed from this exposed part can be formed. It is now possible to perform the bonding operation with the wire and the second position in direct contact, reducing the reliability of the joint due to the presence of an insulating coating material between the core wire and the second position. Therefore, the reliability of the joint between the side portion of the insulated wire and the second position can be ensured.

In addition, since there is no insulation coating between the core wire and the second position, the amount of foreign matter generated due to insulation coating peeling or thermal denaturation is greatly reduced, and the bonding tool Since the core wire of the insulated wire exposed from the part is directly pressed, foreign matter will not get into the bonding tool, ensuring smooth insertion of the insulated wire into the bonding tool, and stabilizing the bonding work. Continuation is possible.

[Example 1] FIGS. 1(a) to 1(i) are process diagrams sequentially showing an example of the operation of an embodiment of the wire bonding method of the present invention,
FIG. 2 is a side view schematically showing the configuration of an embodiment of the wire bonding apparatus of the present invention.

First, the outline of the configuration of the wire bonding apparatus will be explained using FIG. 2.

A bonding stage 2 is arranged on the pedestal 1 so that its elongated direction is perpendicular to the plane of the paper.

On the bonding stage 2, a plurality of tabs 4a are provided in the center at a predetermined pitch in a direction perpendicular to the plane of the paper, each having a semiconductor pellet 3 mounted thereon, and individual tabs 4a.
A lead frame 4 is mounted, which is configured by connecting a plurality of leads 4b, etc., surrounding the semiconductor pellet 3 mounted on the lead frame 4.

A heater 2a is built inside the bonding stage 2, and is configured to heat the placed lead frame 4 and semiconductor pellet 3 to a predetermined temperature.

Furthermore, on the pedestal 1, the bonding stage 2
An x-y table 5, which is movable in a horizontal plane, is provided on the side of the machine.

A bonding head 6 with one end positioned above the bonding stage 2 is supported on the XY table 5 via a swing shaft 7 so as to be swingable in a vertical plane.

The other end of the bonding head 6 is configured to be placed on an X-Y table 5 or connected to a near motor 8 to be driven in the vertical direction.

A bonding arm 9 is horizontally supported at the end of the bonding head 6 on the side of the bonding stage 2, and a capillary 10 is formed to penetrate in the axial direction at the tip located directly above the bonding stage 2. The wire insertion hole (not shown) is fixed in a substantially vertical position.

An ultrasonic oscillator 1 is installed on the base end side of the bonding arm 90.
1 is provided, and from time to time the bonding arm 9 is
The structure is such that a predetermined ultrasonic vibration is applied to a capillary 10 fixed to the tip of the capillary.

An insulated wire 13 unwound from a reel 12 is inserted into a wire insertion hole (not shown) of the capillary.

This insulated wire 13 has a diameter of 25 to 30 μm, for example.
The core wire 13a made of a conductive metal wire (for example, Au) with a thickness of about 1 to 2 μm is coated with an insulating coating made of an insulating polymer material (for example, polyurethane or heat-resistant polyurethane) with a thickness of about 1 to 2 μm. 13b.

In the path of the insulated wire 13 between the capillary 10 and the reel 12, there is a first section that acts to prevent the insulated wire 13 from being fed out from the capillary 10 at any time by restraining the insulated wire 13. A wire clamper 14 is provided in a fixed state on the bonding head 6, and is configured to move up and down together with the capillary 10 by the swinging operation of the linear motor 8 of the bonding head 6.

In this case, a second wire clamper 15 fixed to the pedestal 1 side independently of the bonding head 6 is further provided on the path of the insulated wire 13 between the capillary 10 and the reel 12. , operates independently of the first wire clamper 14 to control the capillary 1 at any time.
The structure is such that an operation is performed to prevent the insulation-coated wire 13 from being drawn out from zero.

Furthermore, although not particularly shown, the capillary 10 and the reel 1
2, the insulation-covered wire 13 is connected to the capillary 10 by blowing airflow at a predetermined velocity from the side onto the insulation-covered wire 13.
A pack tension mechanism is provided that constantly applies a predetermined amount of tension in the direction of pulling the insulated wire back toward the reel 12. When the first wire clamper 14 and the second wire clamper 15 are open, 13 is
It is configured to move in a direction returning to the reel 12 side.

Further, in the vicinity of the capillary 10 fixed to the tip of the bonding arm 9, there is provided a discharge power supply which is movable horizontally in a direction from the bonding stage 2 to just below the tip of the capillary 10 at a predetermined height. A first discharge electrode 16 to which a predetermined discharge voltage is applied between the circuit 18 and the insulated wire 13 at a predetermined timing.
is provided.

Then, at any time, the insulated wire 13 is moved to form a predetermined gap directly below the tip of the insulated wire 13 that protrudes from the tip of the capillary 10 to a predetermined length, and in that state, the insulated wire 1
3, the core wire 13a of the insulated wire 13 is melted and a ball 13C is formed due to surface tension.

In this case, in the vicinity of the first discharge electrode 16 that forms a ball 13c by discharge at the tip of the insulated wire 13, there is a is provided so that it can be freely displaced,
a second discharge electrode 17 connected to the discharge power source 18;
is located.

Then, the insulated wire 13 drawn out from the capillary 10 is approached and faced from both sides with a desired gap, and discharge is generated between the wire 13a and the core wire 13a through the insulated covering 13b, thereby generating discharge energy. Accordingly, the core wire 13a
The insulation coating material 13b covering the insulation coating material 13b is removed by evaporation in a predetermined width in the length direction, and the core wire 13a is exposed to the outside at a predetermined position in the middle of the insulation coating wire 13.
An operation is performed to form a .

In addition, by capturing an image of the semiconductor pellet 3 located directly under the capillary 10 and the lead frame 4 on which the semiconductor pellet 3 is mounted, the bonding head 6 captures a plurality of bonding pads 3a, which will be described later, provided on the semiconductor pellet 3. An image recognition mechanism 19 that recognizes the positions of a plurality of leads 4b surrounding the semiconductor pellet 3, etc.
is provided.

Furthermore, an X-Y table 5. on which the image recognition mechanism 19 and the bonding head 6 are mounted. A near motor 8 for controlling the vertical movement of the bonding 6. First wire clamper 14. Second wire clamper 15. The discharge power supply circuit 18 and the like are collectively controlled by the control unit 20 and operate in cooperation with each other to perform a bonding operation as described below.

Hereinafter, an example of a wire bonding method using a wire bonding apparatus configured as described above will be explained as shown in FIGS. 1(a) to 0.
) etc.

First, by a feeding mechanism (not shown) provided on the bonding stage 2, the lead frame 4 is moved in a direction perpendicular to the paper plane of FIG. At the same time, it is heated to a temperature of about 200° C. by the heater 2a.

The control unit 20 also controls the bonding pad 3 to which the semiconductor pellet 3 is to be bonded, which is positioned directly under the capillary 10 by the image recognition mechanism 19.
The distance between a and the corresponding bonding position on the lead 4b is recognized.

At this time, on the bonding head 6 side, the first
wire clamper 14 and second wire clamper 15
Both are open, and the ball 13a formed at the tip of the insulated wire 13 is held at the tip of the capillary 110 by tension from a back tension mechanism (not shown) (FIG. 1(a)). .

In this state, by appropriately moving the X-Y table 5, the capillary 10 is positioned directly above one of the bonding pads 3a on the semiconductor pellet 3, and at the same time, the linear motor 8 is operated to move the capillary 10. 10 descends onto the target bonding pad 3a and places the ball 13c on the bonding pad 3a.
While pressing with a load of about 150 gf, ultrasonic vibrations of about 60 KHz are applied from the ultrasonic oscillator 11, and the ball 13c is pressed against the bonding pad 3a (Fig. 1 et al.).

Thereafter, by operating the linear motor 8, the capillary 10 moves up while feeding out the insulation-coated wire 13, and the exposed portion 13d of the core wire 13a, which is previously formed in the middle of the insulation-coated wire 13 as described below, is raised. Match the height of the tip to the position (Fig. 1(C)).

Furthermore, by driving the X-Y table 5, the capillary 10 is positioned directly above the desired one of the plurality of leads 4b, and at the same time, the linear motor 8 is driven to lower the capillary 10, exposing the insulated wire 13. Part 13
By applying ultrasonic vibrations while pressing the side surface of the core wire 13H exposed to the outside from d in direct contact with the surface of the lead 4b, the side surface of the core wire 13A is pressed.
It is thermocompression bonded to the surface of the door 4b (FIG. 1 [d]).

At this time, the core wire 13 is
- Since bonding is performed with the lead 4b in direct contact with the lead 4b, the insulation coating 13b and foreign substances generated due to heat denaturation of the insulation coating 13b may be removed from the core wire 13.
a and lead 4b and between core wire 13a and capillary 1
There is no interposition between the tip and the tip of 0.

Therefore, compared to the conventional case where bonding is performed with the insulating coating material 13b interposed, greater bonding strength can be obtained, and the electrical resistance at the bonded portion is smaller, and the core of the insulating coated wire 13 is Good bonding characteristics can be obtained at the bonding portion between the wire 13a and the side bevel 4b.

Further, there is no inconvenience such as foreign matter entering the wire insertion hole of the capillary 10, and the insulated wire 13 is always smoothly fed out and pulled in, so that stable bonding work can be continued for a long time.

Next, the capillary 10 rises from the surface of the lead 4b by a predetermined distance determined by calculation, and then stops (FIG. 1(e)).

Note that between the previous figures 1 (a) to (e), the first
wire clamper 14 and second wire clamper 15
remains open.

Thereafter, with the first wire clamper 14 closed and the insulated wire 13 still restrained, the capillary 10 is
It rises further from the height L+ to a height L and stops, and at this time the insulation-covered wire 3 is cut near the joint of the lead 4b, and one pumping tube of the semiconductor pellet 3 is removed by the installation of the insulation-covered wire 13. Ku,
The electrical connection between the lead 3a and the corresponding one lead 4b of the lead frame 4 is completed (Fig. 1(f)).
).

Next, the second discharge electrode 17, which is placed at a predetermined height L3 from the surface of the lead 4b, approaches from both sides the middle of the insulated wire 13 that has been pulled out from the tip of the capillary 10, and The core wire 1 is inserted through the insulation coating 13b.
3a (section C in Figure 1).

At this time, the electrical discharge energy completely removes the insulation coating 13b at a target distance L4 from the tip of the insulation coating wire 13 by a predetermined length L5 in the axial direction by thermal decomposition or the like, thereby removing the internal core wire 13a. An exposed portion 13d exposed to the outside is formed.

Note that the discharge conditions at this time include, for example, the core wire 13a.
In contrast, the discharge electrode 17 is of negative polarity, and the insulating coating material 13 is
20 as dielectric breakdown voltage at b and gap etc.
00-4000V, discharge current 10-20mA, discharge time 2-10m5. A discharge gap of 0.1 to 0.3+n+n is desirable, and in that case, the insulation coating 13b is 0.1 to 0.3+n+n in the axial direction.
It can be stably removed within the range of 4 to 0.6 mm.

Here, a portion 13d exposed from the tip of the insulated wire 13 is
The length L6 of the insulated wire 13 required for forming a wire loop during the next erection.
(not shown) equal to the sum of the length Lt (not shown) consumed when forming the ball 13C, the center of the exposed portion 13d is set to the side of the lead 4b in the next bonding operation. can be matched to the joining position.

That is, between L1 to L, there is a relationship of L a = L e + L v L = L4 + L2 - L3 ·° · Lt = Ls + Lq + L2 L3 from the geometrical relationship of each part.

Here, the length L6 of the insulated wire 13 required for forming a wire loop during the next installation is determined by the bonding position between the bonding pad 3a and the lead 4b of the semiconductor pellets 3 to be interconnected. The distance between L2 and the height of the wire loop, as well as the length consumed when forming the ball 13C, are determined by the diameter of the core wire 13a and the diameter of the ball 13c, respectively.
Since L3 is determined by the initial settings of the wire bonding equipment, once these conditions are determined, the above-mentioned figure 1 (
The height Ll of the capillary 10 in step e) can be determined by calculation.

That is, the control unit 20 calculates the height of the capillary 10 in the step shown in FIG. It is intended to do so.

Next, as shown in FIG.
3d, first, the second wire clamper 15 closes to restrain the insulated wire 13, and the first wire clamper 14 opens, and in this state, the capillary 10 descends by a distance L8, and the tip of the capillary 10 The distal end of the insulated wire 13 is extended and stopped so as to protrude from the section (FIG. 1(h)).

Here, Le - Lt Ls is established between La, Ls and L1 due to a geometrical relationship. Ls is the insulation coated wire 13 in the next step
This is the length necessary to form the ball 13c at the tip of the ball 13c, and in the case of this embodiment, a suitable length is 0.5 to 1.0 mm. As mentioned above, since Ll can be determined once the above-mentioned conditions are determined, L6 can also be determined by calculation, and the control section 20 sets this length L8 by appropriately controlling the linear motor 8.

Next, first, the first wire clamper 14 is closed to restrain the insulated wire 13, and then the second wire clamper 1'5 is opened, and in this state, the capillary 10 is moved a distance L2 from the surface of the lead 4b. As it rises and stops, the first discharge electrode 16 is placed directly under the capillary 10, and the insulated wire 1 protrudes from the tip of the capillary 10.
3 and a predetermined discharge gap L. (Fig. 1 (1)).

Further, in this state, a discharge is generated between the tip of the insulated wire 3 and the first discharge electrode 16, and at this time, the insulating coating material 13b at the tip of the insulated wire 13 is thermally decomposed due to the discharge energy. removed by and core wire 1
The tip of 3a melts and forms a ball 13C due to its own surface tension (FIG. 1 (J)).

Thereafter, the first wire clamper 14, which had been closed, is opened, and the reel 12 is opened by a back tension mechanism (not shown).
The insulation coated wire 13 is pulled back by the tension acting in the direction of , and the ball 13c at the tip of the core wire 13a is held at the tip of the capillary 10, resulting in the state shown in FIG. 1(a), and the next bonding operation is performed. becomes possible.

Note that if the height of the first discharge electrode 16 from the surface of the lead 4b is Ll+, and the discharge with the tip of the insulated wire 13 is a gap LIG, then L2 = L9+ Llo
Since +L and l+ hold, the rising height L2 of the capillary 10 in the process shown in FIG. 10 rising height L2
Perform the action to set.

Further, as conditions for forming the ball 13c by the first discharge electrode 16, in the case of this embodiment, the above-mentioned second
Regarding the conditions for forming the exposed portion 13d by the discharge electrode 17, it is desirable to discharge at a large current and for a short time. For example, the discharge electrode 16 is set to have a negative polarity with respect to the exposed portion 13d, and the discharge time is 0.5 to 20 m5. It is possible to set the discharge current to 30 to 100 mA.

In this way, by repeating the series of steps shown in FIGS. 1(a) to (i), each of the plurality of ball pads 3a of the semiconductor pellet 3 and each of the plurality of leads 4b on the corresponding lead frame 4 side A wire bonding operation is performed to establish an electrical connection by constructing an insulated wire 13 with the insulated wire 13.

Incidentally, since a series of bonding steps are repeated and the explanation becomes complicated, a detailed explanation is avoided at the beginning, but in the case of this embodiment, a plurality of bonding pads 3a of each semiconductor pellet 3 and each At the beginning of each bonding operation with a plurality of corresponding leads 4b, as described above, the insulated wire 13 is bonded based on the distance between the bonding pad 3a that is the first bonding combination and the bonding position of the lead 4b.
It is necessary to form the exposed portion 14d in advance at a predetermined position in the middle.

Therefore, in the case of this embodiment, prior to the actual wire bonding operation on each semiconductor pellet 3, some parts, such as the side ends of the lead frame 4, are cut off and discarded in the future sealing process. , bonding of the semiconductor pellet 3, which is the first bonding combination, is performed by performing a disposable bonding operation by the series of operations shown in FIGS. 1(a) to (J) using an area unrelated to product quality. Depending on the distance between the pad 3a and the bonding position of the lead 4b, as shown in FIG. 1(a),
The core wire 13 is placed at an appropriate distance from the tip of the insulated wire 13.
The operation for forming the exposed portion 13d of a is performed.

As explained above, according to this embodiment, the insulation coating material 13b at the planned bonding position to the lead 4b in the middle of the insulation coating wire 13 is removed in advance, and as shown in FIG.
d), when bonding the side surface of the insulated wire 13 and the lead 4b, bonding is performed with the core wire 13a and the lead 4b in direct contact without the intervening insulating material 13b. Therefore, the insulating sheathing material 13b and foreign matter generated due to heat denaturation of the insulating sheathing material 13b may be present between the core wire 13a and the lead 4b and between the core wire 1.
3a (!: There is no interposition between the capillary and the tip of the capillary 10.

Therefore, compared to the conventional case where bonding is performed with the insulating coating material 13b interposed, greater bonding strength can be obtained, and the electrical resistance at the bonded portion is smaller, and the core of the insulating coated wire 13 is Good bonding characteristics can be obtained at the bonding portion between the side surface of the wire 13a and the lead 4b.

As a result, in the semiconductor integrated circuit device, for example, after assembly, the joint portion of the insulated wire 13 with the lead 4b does not peel off inadvertently, thereby preventing product defects.
The quality and operational reliability of semiconductor integrated circuit devices are improved.

Furthermore, foreign matter may enter the wire insertion hole of the capillary 10 and block the insertion hole of the insulation-covered wire 13 in the capillary 10, thereby preventing smooth feeding and retraction of the insulation-covered wire 13 from the capillary 10. Since the insulating coated wire 13 can always be smoothly fed out and pulled in without causing any inconvenience, stable bonding work can be continued for a long time.

As a result, the maintenance and management of the wire bonding apparatus is simplified, the operating rate is improved, and the productivity in the wire bonding process of semiconductor integrated circuit devices is improved.

[Embodiment 2] FIG. 3 is a perspective view showing the main parts of a wire bonding apparatus according to an embodiment of the present invention, and FIG.
Furthermore, it is a cross-sectional view showing a part thereof in an enlarged manner.

In the wire bonding apparatus of the second embodiment, the second discharge electrode 170 that forms the exposed portion 13d in the middle of the insulated wire 13 is made of a conductive material such as tungsten (W), and On both sides of the pair of electrode pieces 170a and 170b facing each other through the electrode pieces 170a and 170b, the insulated wire 13
It is constructed of insulating pieces 170c and 170d made of an insulating material such as ceramics and fixed to protrude from the side thereof.

The insulating pieces 170c and 170d prevent the insulating covered wire 13 from coming into direct contact with the pair of electrode pieces 170a and 170b, which face each other with a predetermined gap between them and sandwiching the insulated wire 13 from both sides. It is something.

Further, in this case, the second discharge electrode 170 is
1, and a solenoid 172a coaxially supported by this swing shaft 171, each having an individual end.

A plurality of swing arms 173a are locked to 172b.

173b, and the plurality of swinging arms 173a, 173b.
a pair of parallel guides 7-A 174a, the base end of which is fixed to the other end, and the pair of electrode pieces 17Qa, 170b of the second discharge electrode respectively locked to the distal end;
174b, a swing shaft 171 and a plurality of solenoids 17
2a and 172b, and is configured to be driven by a discharge electrode drive mechanism A comprising a frame member 175 fixed to the x-y table 5.

Further, between each of the plurality of swinging members 173a, 173b and the side of the frame member 175, a spring 176a is provided that constantly applies a rotational force in a direction to rotate each of the swinging members 173a, 173b in a predetermined direction.
, 176b are provided.

Furthermore, a gap adjustment piece 177 that is locked on the side of the swing arm 173b is provided on the opposing surfaces of the end portions of the swing arms 173a and 173b that support the proximal ends of the guide arms 174a and 174b. The swing arm 173a
, 173b due to the swinging displacement of the guide arms 174a, 1.
74b, that is, the minimum gap between the pair of electrode pieces 170a and 170b of the second discharge electrode 170 is configured to be stably realized.

That is, when the second discharge electrode 170 is not used, the solenoid 172a is relaxed and the swing arm 173a is rotated by the biasing force of the spring 176a.
By operating the solenoid 172b and rotating the swinging arm 173b against the urging force of the spring 176b, the electrode piece 1 is moved through the guide arms 174a and 174b.
An operation is performed in which 70a and 170b are moved away from each other.

In addition, when in use, the reference position is set by activating the solenoid 172a and rotating the swinging arm 173a to a predetermined position against the biasing force of the spring 176a, while relaxing the solenoid 172b. spring 17
By rotating the swinging arm 173b by the biasing force of the swinging arm 173b to a position where the gap adjustment piece 177 abuts the swinging arm 173a on the opposite side, the second discharge electrodes 170 facing each other with the insulated wire 13 in between are connected. electrode piece 17Qa,
Insulating piece 170c, electrode piece 170b, insulating piece 170d
The gap between the insulation coated wire 13 and the side surface of the insulated wire 13 is precisely controlled to a predetermined setting value.

That is, in the case of this embodiment, as shown in FIG.
The gap between the electrode pieces 170a and 170b is 11, and the amount of protrusion of the insulating pieces 170c and 170d from each of the electrode pieces 170a and 170b is 12.
Further, assuming that the outer diameter of the insulated wire 13 is 13, the discharge gap 14 is as follows: 12 ≦l, ≦jl! 2-+-1/2 (L-A
s).

Here, for example, L = 0. 2mm, j! ,
=Q1mm, l13=0. 0.3 mm, the discharge gap β can be precisely set in the range of 0.2 mm≦14≦0.2035 mm from the above formula.

In this way, according to the second embodiment, the second discharge electrode 17
When forming the exposed portion 13d by discharging between the core wire 13a and the insulated wire 13, the discharge gap β4 can be set with high precision, and short circuits between the core wire 13a and the electrode pieces 170a and 170b during discharge can be prevented. Piece 170c, 17
Since it can be reliably prevented by 0d, it becomes possible to perform extremely stable discharge, and the formation range and position of the exposed portion 13d formed by discharge in the middle of the insulated wire 13 can be controlled with high precision.

[Embodiment 3] FIGS. 5(a) to 5(5) show an example of a wire bonding method according to another embodiment of the present invention in the order of steps.

First, the capillary 10 is positioned directly above the target bonding pad 3a of the semiconductor pellet 30, and at this time, the insulated wire 13 inserted through the capillary 10
is a ball 13C from the tip of the capillary 10 to the tip.
The wire is restrained by the first wire clamper 14 in a state where it protrudes by the length necessary for forming the wire (FIG. 5(a)).

In this state, the first discharge electrode 160 enters from the side below the tip of the insulated wire 13 with a predetermined discharge gap, and discharges with the tip of the insulated wire 13, thereby causing the ball. 13C is formed (FIG. 5(b)).

Thereafter, the first discharge electrode 160 retreats to the side, and the capillary 10 descends by a predetermined distance with only the first wire clamper 14 closed (FIG. 5(C)).
.

At this time, the ball 13C of the insulated wire 13 is not in contact with the bonding pad 3a of the semiconductor pellet 3 below.

Next, with the first wire clamper 160 open, the capillary 10 rapidly rises to a predetermined height, and due to the inertia of the insulated wire 13, the tip of the capillary 10 reaches a predetermined length. The insulated wire 13 is now in an unwound state.

After stabilizing the insulation-coated wire 13 by closing the second wire clamper 15 in this state, the first
discharge electrodes 160 approach each other with a predetermined discharge gap.

Then, by discharging between the core wire 13a and the second discharge electrode 160 via the insulating coating material 13b, the discharge energy causes the exposed portion 13d to be located at a predetermined length from the tip of the insulating coated wire 13. is formed (Fig. 5(d))
).

Thereafter, by retracting the first discharge electrode 160 to the side and opening the second wire clamper 15, the insulated wire 13 is pulled back toward the reel 12 by the tension constantly applied from the pack tension mechanism. As a result, the ball 13C at the tip is held at the tip of the capillary 10 (FIG. 5(e)).

Next, with the first wire clamper 14 and the second wire clamper 15 kept open, the capillary 10 descends onto the target bonding pad 3a of the semiconductor pellet 3, and presses the ball 13C against the bonding pad 3a. The ball 13c of the insulated wire 13 is pressed onto the bonding pad 3a (FIG. 5 (f)).

Thereafter, the capillary 10 has its tip portion shown in FIG.
), the core wire 13a that is exposed from the exposed portion 13d is raised to a height that corresponds to the position of the exposed portion 13d that has already been formed, and then moved in the direction of the target lead 4b and lowered. While pressing the side surface against the surface of the lead 4b, ultrasonic vibration is applied to make the lead 4b crimped (FIG. 5).

At this time, in the case of this embodiment as well, as in the case of the first embodiment, there is no insulating coating material 13b interposed between the side surface of the core wire 13a and the surface of the lead 4b, so that sufficient bonding strength can be achieved. As a result, highly reliable bonding can be performed, and the insulating coating material 13b or a part of it caused by thermal denaturation does not adhere to the tip of the capillary 10.

Next, the capillary 10 was once raised to a height at which the insulated wire 13 was fed out by the length necessary to form the ball 13c, and then stopped, and the first wire clamper 14 was closed to restrain the insulated covered wire 13 from being fed out. Later, by further raising the capillary 10, the tip of the insulated wire 13 is torn off from the joint on the lead 4b side (FIG. 5(h)).

By positioning the capillary 10 at a predetermined height directly above the bonding pad 3a to be bonded next to the semiconductor pellet 13, the capillary 10 is prepared for the next bonding operation and is in the state shown in the first item 5(a). Thus, a series of bonding operations between the - group of bonding pads 3a and leads 4b is completed.

As described above, according to the third embodiment, as in the case of the first embodiment, there is no insulating coating material 13b interposed between the side surface of the core wire 13a and the surface of the lead 4b, so that sufficient bonding strength can be achieved. is obtained, highly reliable bonding is performed, and the insulation coating material 13b or a part of it caused by thermal denaturation does not adhere to the tip of the capillary 10, so that the insulation coating from the capillary 10 is always maintained. The wire 13 can be smoothly fed out and pulled back, and stable bonding work can be continued for a long time.

In the case of the third embodiment, the length of the insulated wire 13 to be fed out to form the exposed portion 13d is determined by vertical movement of the capillary 10 without using the bonding of the tip of the insulated wire 13 to the lead 4b. Since the thickness is controlled, there is no need for a discard bonding operation as in the case of the first embodiment.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

That is, according to the wire bonding method of the present invention, an insulated wire inserted through a bonding tool is used, an operation of bonding the tip of the insulated wire to a first position, and an operation of bonding the tip of the insulated wire to a first position, and A wire bonding method for electrically connecting a first position and a second position by performing an operation of joining a side part of the insulated wire to a second position, the wire bonding method comprising: Then, the insulation-covered wire is pulled out from the tip of the bonding tool by a required length calculated based on the position information of the second position, and the center of the insulation-covered wire is pulled out from the tip of the bonding tool by a required length calculated based on the position information of the second position. A discharge is caused to occur between the wire and the discharge electrode through the insulating coating, and the insulating coating is removed by the discharge energy at that time to form an exposed portion of the core wire, and this exposed portion is moved to the second position. Since the core wire exposed from the exposed portion is in direct contact with the second position, the bonding operation can be performed with the core wire exposed from the exposed part and the second position. The reduction in reliability of the joint due to the presence of
Reliability of the joint between the side surface of the insulated wire and the second position can be ensured.

In addition, since there is no insulation coating between the core wire and the second position, the amount of foreign matter generated due to insulation coating peeling or thermal denaturation is greatly reduced, and the bonding tool Since the core wire of the insulated wire exposed from the part is directly pressed, foreign matter will not get into the bonding tool, ensuring smooth insertion of the insulated wire into the bonding tool, and stabilizing the bonding work. Continuation is possible.

Further, according to the wire bonding apparatus of the present invention,
A bonding tool is provided with an insulated wire inserted therethrough and capable of three-dimensional displacement relative to the object, and a discharge electrode that periodically generates an electric discharge between the insulated wire and the electric discharge. An operation of bonding the tip of the insulated wire with a ball formed thereon to a first position, and the insulated wire fed out from the bonding tool.

A wire bonding device that electrically connects a first position and a second position by performing an operation of joining a side surface portion to a second position, the wire bonding device electrically connecting the first and second positions. The required length of the insulated wire to be installed at the first and second positions is calculated based on the position information, and the required length of the insulated wire is extended from the tip of the bonding tool to the required length based on the calculation result. The length is pulled out, and a discharge is caused to occur between the core wire of the insulating coated wire and the discharge electrode through the insulating coat at the part where it is planned to be joined to the second position, and the discharge energy at that time causes the insulating coat to be removed. Since the core wire is removed to form an exposed portion and this exposed portion is joined to the second position, for example, by appropriately controlling the first and second wire clampers that operate independently, By controlling the feeding of the insulation-covered wire from the bonding tool, the side surface of the insulation-covered wire relative to the second position is placed at a desired bonding site at a desired distance from the tip of the insulation-covered wire. Prior to bonding, the insulation coating may be removed to form an exposed portion of the core wire, and the bonding operation may be performed with the core wire exposed from this exposed portion being in direct contact with the second position. This eliminates the reduction in reliability of the joint caused by the presence of insulation coating material between the core wire and the second position. The reliability of the joint can be ensured.

In addition, since there is no insulation coating between the core wire and the second position, the amount of foreign matter generated due to insulation coating peeling or thermal denaturation is greatly reduced, and the bonding tool Since the core wire of the insulated wire exposed from the part is directly pressed, foreign matter will not get into the bonding tool, ensuring smooth insertion of the insulated wire into the bonding tool, and stabilizing the bonding work. Continuation is possible.

[Brief explanation of the drawing]

1(a) to ('') are process diagrams sequentially showing an example of the operation of an embodiment of the wire bonding method of the present invention, and FIG. 2 is a schematic diagram of the configuration of an embodiment of the wire bonding apparatus of the present invention. 3 is a perspective view showing a main part of a wire bonding apparatus according to an embodiment of the present invention, FIG. 4 is a cross-sectional view showing a further enlarged part of the wire bonding apparatus, ) to (Company) are explanatory diagrams showing an example of a wire bonding method according to another embodiment of the present invention in the order of steps. 1... Frame, 2... Bonding arm, 2a...
・Heater, 3... Pellet, 3a... Bonding pad, 4... Lead frame, 4a... Tab, 4b... Lead, 5... XY table,
6... Bonding head, 7... Swing axis, 8...
・Linear motor, 9...Bonding arm, 10・
...Capillary, 11...Ultrasonic oscillator, 12...
Reel, 13... Insulation coated wire, 13a... Core wire, 13b... Insulation coating material, 13C... Ball, 13
d...Exposed part, 14...First wire clamper, 1
5... Second wire clamper, 16,160... First discharge electrode, 17,170... Second discharge electrode, 1
70a, 170b...electrode pieces, 170c, 170d...
... Insulating piece, 18 ... Discharge power supply circuit, 19 ... Image recognition mechanism, 20 ... Control section, A ... Discharge electrode drive mechanism. Agent Patent Attorney Yamato Tsutsui (d) Figure (b) (C) 6a (6) (d) 3a (3) (e) Figure (Cl) (h)

Claims (1)

[Claims] 1. Using an insulated wire inserted through a bonding tool, joining the tip of the insulated wire to a first position; and A wire bonding method for electrically connecting a first position and a second position by performing an operation of joining a side part to a second position, the wire bonding method comprising: The insulation-covered wire is pulled out from the tip of the bonding tool by a required length calculated based on the position information of A discharge is caused to occur through an insulating coating between the core wires, and the insulating coating is removed by the discharge energy at that time to form an exposed portion of the core wire, and this exposed portion is joined to the second position. Characteristic wire bonding method. 2. A first step of forming a ball at the tip of the insulated wire by electric discharge, a second step of drawing the ball into the tip of the bonding tool, and bonding the ball at the first position. a third step; a fourth step of joining the core wire exposed portion of the insulated wire to the second position by moving the bonding tool while feeding out the insulated covered wire; a fifth step of cutting the insulation-covered wire from the second position by feeding out the insulation-covered wire to a desired length and stopping the feeding; a sixth step of forming an exposed portion of the core wire by causing an electric discharge to occur between the planned bonding site for the second position and the discharge electrode, and leaving a length necessary for forming the ball; 2. The wire bonding method according to claim 1, wherein the seventh step of pulling the insulated wire into the bonding tool is repeated. 3. The first and second positions are a bonding pad of a semiconductor pellet and a lead of a lead frame on which the semiconductor pellet is mounted, respectively, and actual bonding between the bonding pad of each semiconductor pellet and the lead Prior to the operation, by performing a dummy bonding operation in which the first to seventh steps are performed on a part of the lead frame as needed, the initial exposed core portion is formed and the exposed core portion is removed from the exposed core portion. 3. The wire bonding method according to claim 1, wherein the length to the tip is adjusted. 4. an eighth step of forming a ball at the tip of the insulated wire by electric discharge; a ninth step of drawing out the insulated wire by the required length from the bonding tool; a tenth step of forming an exposed portion of the core wire by causing an electric discharge to occur between a portion of the insulating coated wire to be bonded to the second position and the discharge electrode; an eleventh stage of pulling into the tip of the
a twelfth step of bonding the ball to the first position; and a step of moving the bonding tool while feeding out the insulated wire to move the core wire exposed portion formed in the tenth step to the second position. The first to be joined at the position of
Step 3: Paying out a desired length of the insulated wire from the bonding tool to form the ball while moving the bonding tool, and cutting the insulated wire from the second position by stopping the payout. 2. The wire bonding method according to claim 1, further comprising a fourteenth step of performing. 5. The wire bonding method according to claim 1, wherein the first and second positions are a bonding pad of a semiconductor pellet and a lead of a lead frame on which the semiconductor pellet is mounted, respectively. 6. The withdrawal and retraction operations of the insulated wire from the bonding tool are performed by a first wire clamper that moves together with the bonding tool and a second wire clamper that is fixed independently of the bonding tool. 6. The wire bonding method according to claim 1, wherein the clamping of the insulated wire and the release of the clamping state are independently controlled. 7. A bonding tool through which an insulated wire is inserted, and which is capable of three-dimensional displacement relative to the object;
a discharge electrode that periodically generates a discharge between the insulation-coated wire and the insulation-coated wire, the distal end of the insulation-coated wire having a ball formed by the discharge being bonded to a first position; The wire bonding apparatus electrically connects the first position and the second position by performing an operation of joining the side part of the insulated wire to the second position, the wire bonding apparatus comprising: The required length of the insulated wire to be installed at the first and second positions is calculated based on the first and second position information, and based on the calculation result, the length of the insulated wire from the tip of the bonding tool is calculated. Pull out the insulated wire to the required length,
A discharge is caused to occur between the core wire of the insulated wire and the discharge electrode at the site where it is to be joined to the second position through the insulated coating, and the discharge energy is used to remove the insulated coating and connect the core to the second position. A wire bonding apparatus characterized in that an exposed portion of the wire is formed and the exposed portion is bonded to the second position. 8. A first step of forming a ball at the tip of the insulated wire by electric discharge, a second step of drawing the ball into the tip of the bonding tool, and bonding the ball at the first position. a third step; a fourth step of joining the core wire exposed portion of the insulated wire to the second position by moving the bonding tool while feeding out the insulated covered wire; a fifth step of cutting the insulation-covered wire from the second position by feeding out the insulation-covered wire to a desired length and stopping the feeding; a sixth step of forming an exposed portion of the core wire by causing an electric discharge to occur between the planned bonding site for the second position and the discharge electrode, and leaving a length necessary for forming the ball; By repeating the seventh step of pulling the insulated wire into the bonding tool, a plurality of sets of the first position and the second position on the object are individually connected by the insulated wire. 8. The wire bonding apparatus according to claim 7, wherein the wire bonding apparatus performs the following operations. 9. The object is a lead frame on which a semiconductor pellet is mounted, the first and second positions are a bonding pad of the semiconductor pellet and a lead of the lead frame, respectively, and the bonding of each semiconductor pellet is Prior to the actual bonding operation between the pad and the lead, the first to seventh steps may be performed at any time.
3. A dummy bonding operation is performed on a part of the lead frame to perform the step of forming the core wire exposed portion initially and adjusting the length from the core wire exposed portion to the tip end. 9. The wire bonding device according to 7 or 8. 10. An eighth step of forming a ball at the tip of the insulated wire by electric discharge, and a ninth step of pulling out the insulated wire by the required length from the bonding tool.
and a tenth step of forming an exposed portion of the core wire by causing discharge to occur between the discharge electrode and a portion of the insulated wire pulled out from the bonding tool to be bonded to the second position. an eleventh step of drawing the ball into the tip of the bonding tool, a twelfth step of bonding the ball to the first position, and moving the bonding tool while feeding out the insulated wire. a thirteenth step of bonding the core wire exposed portion formed in the tenth step to the second position; and a thirteenth step of bonding the core wire exposed portion formed in the tenth step to the second position, and removing the wire from the bonding tool for forming the ball while moving the bonding tool. 8. The wire bonding apparatus according to claim 7, further comprising a fourteenth step of feeding out the insulation-covered wire to a desired length and cutting the insulation-covered wire from the second position by stopping the feeding. 11. Claim 7, wherein the object is a lead frame on which a semiconductor pellet is mounted, and the first and second positions are a bonding pad of the semiconductor pellet and a lead of the lead frame, respectively.
Or the wire bonding apparatus according to 10. 12. A first wire clamper that moves together with the bonding tool, and a second wire clamper that is provided independently of the bonding tool, and the drawing and retracting operations of the insulated wire from the bonding tool. Claims 7, 8, 9, 10, or 11, wherein the first wire clamper and the second wire clamper independently control the clamping or release of the clamping state of the insulated wire. The wire bonding device described. 13. A first discharge electrode that forms the ball at the tip of the insulation-covered wire, and a second discharge electrode that forms an exposed portion of the core wire of the insulation-covered wire. The wire bonding apparatus according to claim 7, 8, 9, 10, 11 or 12. 14. The wire bonding apparatus according to claim 13, wherein the second discharge electrode is comprised of a pair of electrode pieces that are openably and closably arranged to face each other with a predetermined gap between them via the insulated wire. 15. The wire bonding apparatus according to claim 14, wherein an insulating material, which is in contact with the outer periphery of the insulating coated wire, protrudes from opposing portions of the pair of electrode pieces constituting the second discharge electrode. 16. A swinging shaft, a plurality of swinging arms coaxially supported by the swinging shaft, each having one end locked to a separate solenoid, and a base end at the other end of the plurality of swinging arms. is fixed thereto, and includes a pair of guide arms at the distal end portions of which the pair of electrode pieces of the second discharge electrode are respectively locked, and the pair of electrode pieces of the second discharge electrode are fixed to each other. 16. The wire bonding apparatus according to claim 13, 14, or 15, wherein the wire is electrically discharged from the core wire of the insulation-covered wire while facing the insulation-covered wire with a desired gap therebetween.