JPH08203965A - Bonding tool and lead connection structure body - Google Patents

Abstract

PURPOSE: To realize collective connection of total leads with high reliability, independently of the reduction of lead pitch and lead width and multilead configuration which are caused by high density high level integration of electronic components. CONSTITUTION: A leading-out lead 19 extruded from a TAB package is made to abut against an electrode 17 on a circuit board 16, and connected with the electrode 17 by heating and pressing with a bonding tool 31 descending from above. Divided pressing parts 32a, 32b which are divided into two rows of inside and outside are collectively fixed, via solder material, to the tip part of body material 34 of the bonding tool 31. The gap 32a, of the outside divided pressing part 32a faces the inside divided pressing part 32b in the inside outside direction. The gap 32b, of the inside divided pressing part 32b faces the outside divided pressing part 32a, in the inside outside direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding tool for connecting an external lead lead from an electronic component such as an integrated circuit element to an electrode of a circuit board by heating and pressing, and a connecting tool manufactured by the bonding tool. And a lead connection structure.

[0002]

2. Description of the Related Art In recent years, as a connection method for obtaining electrical continuity from a semiconductor chip to the outside, three-dimensional mounting contributing to improvement of added value of equipment, ease of electrical characteristic inspection, thin and small package The TAB (Tape Automated Bonding) method, which has the advantages of being able to be used, is widely adopted.

Regarding the TAB connection, an inner lead bonding step of connecting the inner leads of the film carrier and the electrodes of the semiconductor chip via protruding electrodes (bumps), and the outer leads of the film carrier and the electrodes of the circuit board are connected to each other. There is an outer lead bonding process for connecting.

The latter outer lead bonding step will be described below with reference to FIG.

The bonding tool 11 includes a pressurizing portion 12 via a brazing material 13 at the tip of a body (shank) material 14.
Are joined together.

After the inner lead bonding process,
Samples judged to be non-defective after the resin coating process and electrical inspection process are completed are long organic film 2 made of polyimide or the like.
From above, punching and forming of the external lead 19 are performed. The inner leads on the organic film 21 are connected to the semiconductor chip 20 via protruding electrodes 22. The formed TAB package 18 has Sn or solder or Au plated external lead leads 19 in the package 18 as Sn.
It is aligned with and brought into contact with the electrode 17 on the circuit board 16 treated with solder or Au. The circuit board 16 is previously mounted on the bonding stage 15 in a positioned state.

Next, the bonding tool 11 heated to 250 to 500 ° C. is lowered, and the pressure of the pressure of 50 to 100 g / lead is applied for 0.5 to 3.0 seconds. The contact portion of the electrode 16 with the electrode 17 is heated and pressed, and all the leads are collectively thermocompression bonded. The bonding stage 15 is usually preheated to a temperature of about 150 ° C., which is lower than the bonding temperature, by a built-in heater 23 in order to reduce thermal shock during bonding. Here, when the lead 19 is Sn-plated and the electrode 17 of the circuit board 16 is Au-treated, a eutectic alloy is formed and is connected by it. The above-mentioned connection conditions are appropriately selected according to the material of the surface treatment of the leads 19 and the electrodes 17.

The heating method of the bonding tool 11 used for such bonding is a "pulse heating method" in which a pulse current is instantaneously applied to the bonding tool 11 for heating only during bonding, and a heater 24 is used for the bonding tool 11. There is a "constant heat system" that has a built-in, and constantly heats.

In the constant heat type bonding tool 11, as shown in FIG. 6 (a), generally, a stainless steel or a super steel material is used for the body material 14, and the pressing portion 12 is used.
In terms of hardness and cleaning properties, is sintered diamond or C
The pressure unit 12 is joined to the body member 14 through a brazing filler metal 13 such as Ag using BN (Cubic Boron Nitride).

Conventionally, as the shape of the pressing portion 12 at the tip of the bonding tool 11, as shown in FIG.
Along the four sides of the front surface of the tip part, the letter-shaped pressure part 12a is
6 separately formed, or as shown in FIG. 6C, a pressure part 1 in which a single-character pressure part is equally divided on each side.
2b is formed.

In the case where the four sides shown in FIG. 6 (b) are the pressing portions 12a each having a single letter shape, the bonding tool 11 is used.
Due to the variation in temperature distribution due to the shape and the thermal conductivity of the material, and the difference in thermal expansion between the materials when the pressure member 12a is brazed to the body material 14, the pressure member 12a becomes flat at room temperature. Even if it is processed, when it is heated to a high temperature, a large concave warp is generated in the pressing portion 12a. This is because the pressing portion 12a is relatively elongated. As the tip size of the bonding tool 11 increases as the chip size increases, the pressurizing portion 12a becomes longer and the tendency of warping increases.

For example, the pressure part 12a is made of Inconel (coefficient of thermal expansion: 16.0 × 10 ^-6 / ° C.) and each side is 20 mm × 1.
With the bonding tool 11 having a size of mm,
When heated to 300 ° C, 40μ at both ends of the pressure part 12a
A strain of m or more occurs and a concave warp occurs. That is, when the lead 19 and the electrode 17 are connected to each other by the one-character type pressurizing portion 12a, a large concave warp is generated on the surface of the pressurizing portion 12a due to heating at the time of connection, and a strong pressure is applied to each corner portion. , And the lead 19 between each corner
Insufficient pressure cannot be applied to the tube, resulting in poor connection.

For the reasons mentioned above, in general,
In the case of connecting all the leads at once, the bonding tool 11 having a plurality of divided pressing portions 12b obtained by equally dividing the one-letter shape on each side shown in FIG. 6C is used.
In this bonding tool, since each of the divided pressing portions 12b is short, it is possible to suppress the occurrence of warpage.

[0014]

However, in recent years,
I for high density and high integration of semiconductor chips such as LSI
There is a tendency for the number of / O ports to increase (more leads), lead pitch, and lead width to decrease, and there are a plurality of pressure portions 12b obtained by equally dividing one letter type on each side shown in FIG. 6C. Even with the bonding tool 11, as shown in FIG.
When the external lead-out leads 19 are collectively connected to the electrodes 17 of the circuit board 16, depending on the pitch or the lead width of the leads 19, the divided pressurizing portions 12b do not correspond in a correct positional relationship, and the adjacent pressurizing portions 12b adjacent to each other. When the lead 19 corresponds to the gap 12b ₁ of the above, a lead as shown by 19a which cannot receive sufficient pressure is generated (one is not pressed to the lead itself, and the other is attached to the lead by a bonding tool). As a result of one-sided contact of the pressure part, the leads are tilted), a satisfactory connection state cannot be obtained, and the connection reliability becomes poor.

This is because in order to suppress warpage at high temperature,
This is because the pressing portion 12b has one side divided into a plurality of parts. On the other hand, if the pressurizing portion is lengthened, a concave warp occurs, which also leads to a decrease in connection reliability.

The present invention was conceived in view of the above circumstances, and leads to a reduction in lead pitch, lead width, and a large number of leads, which accompanies the higher density and higher integration of electronic components such as semiconductor chips. The aim is to provide a bonding tool that can achieve a collective connection of all leads with high connection reliability, regardless of the trend toward higher density. It is an object of the present invention to provide a lead connection structure which is mounted but has high connection reliability.

[0017]

A first aspect of the present invention.
In the bonding tool described in (1), at least two rows of pressurizing portions, each of which is divided into a plurality of rows, are integrally fixed to each side of the tip portion of the body material. In the row of parts, a part of the divided pressurizing section located on the outside and a part of the divided pressurizing section located on the inner side are overlapped in the inward and outward directions, and a gap between adjacent parts of the outer divided pressurizing section is the inner side. It is characterized in that they are arranged so as to face the divided pressurizing portions in the inward and outward directions.

A bonding tool according to a second aspect of the present invention is the bonding tool according to the first aspect, in which the rows of the inner and outer split pressurizing portions are two rows, and the split pressurizing portions of each row are equally divided to have a length. They are substantially equal to each other, and the gap between the outer divided pressurizing portions is located substantially at the center of the inner divided pressurizing portions in the length direction.

The lead connection structure according to claim 3 of the present invention is the lead connection structure manufactured by the bonding tool according to claim 1 or 2, wherein a large number of leads extending from the electronic component are provided. And a large number of electrodes on the circuit board are contacted and bonded to each other, and the connection positions of the leads to the electrodes in the lead longitudinal direction are not the same position.

According to a fourth aspect of the present invention, there is provided the lead connecting structure according to the third aspect, wherein the connecting positions of the leads with respect to the electrodes in the longitudinal direction of the lead are alternately staggered for each adjacent lead, and are arranged in a zigzag shape as a whole. It is characterized by being arranged.

[0021]

In the bonding tool according to the first aspect of the present invention, since each of the pressing parts in each row is divided into a plurality of parts, and the length of each divided pressing part is shortened, warpage at high temperature is prevented. To be done. In addition, since the gap in the outer split pressurizing portion is covered by the inner split pressurizing portion, the gap in the inner split pressurizing portion is covered by the outer split pressurizing portion. Since all the leads are pressed by one of the divided pressing parts, the lead pitch, the lead width can be reduced and the number of leads can be increased in accordance with the high density and high integration of electronic components such as semiconductor chips. In addition, there is no region where a defective connection between the lead and the electrode occurs on each side.

In the bonding tool according to the second aspect of the present invention, both the prevention of warpage and the collective connection of all leads are satisfied, the structure is the simplest, and the connection state of all connection points is made uniform.

In the lead connection structure according to the third and fourth aspects, the semiconductor chip with high density and high integration is mounted, and the lead pitch and lead width are reduced and the number of leads is increased. Nevertheless, all the leads have high reliability of connection with the electrodes on the circuit board.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a bonding tool according to the present invention and an embodiment of a lead connection structure connected and manufactured by the bonding tool will be described in detail below with reference to the drawings.

FIG. 1 (a) is a perspective view of the bonding tool arrangement according to the embodiment when the bonding tools are arranged upside down when the pressing portions at the tip are arranged upside down, and FIG. 1 (b) is shown in FIG. ) Is a plan view showing the arrangement of the pressurizing sections in the state of FIG. 1C, and FIG. 1C is a front view of the lower side portion when the bonding tool is in the normal posture. 2 is a schematic front view of a main part showing a state during a bonding operation, FIG. 3 is a plan view of the main part showing a bonding state corresponding to FIG. 2 on only one side, and FIG. 4 is a manufactured lead connection structure. It is a schematic perspective view of a body. In FIG. 2 and FIG. 3, the number of electrodes 17 and leads 19 shown is only six, but in reality
The number is up to about 100, which is difficult to understand as it is, so only 6 are provided for easy understanding.

The bonding tool 31 has an outer divided pressurizing portion 32a which is divided into a plurality of rows in two rows along each of the four sides of the square at the tip of the body (shank) material 34. And the inner pressurizing section 32b
And the brazing filler metal 33 are integrally fixed to each other. The body material 34 is made of stainless steel or super steel material, and the divided pressing portions 32a, 32b are made of sintered diamond, CBN (Cubic Boron Nitride), or the like.
Ag brazing or the like is used as the brazing material 33.

The outer divided pressure portion 32a has a structure in which one side is equally divided into four, and the inner divided pressure portion 32b has a structure in which one side is equally divided into three. The total length of one side is about 20 mm, and regarding the size of each divided pressing portion 32a, 32b, the sintered diamond (coefficient of thermal expansion: 3.0 to 3. 8x1
Constituted by 0 ^-6 / ° C.), even when heated to about 400 ° C., the extent of dimension connection failure does not occur in the warp caused by thermal strain and electrode 17 of lead 19 and the circuit board 16,
That is, the length is about 4 mm and the thickness is about 0.2 mm.

Both the outer pressure-applying portion 32a and the inner pressure-applying portion 32b are equally divided and have the same length. Each part of the outer divided pressurizing portion 32a and each part of the inner divided pressurizing portion 32b overlap each other in the inner and outer directions. The gap 32a ₁ between adjacent ones of the outer divided pressurizing portions 32a faces the substantially central position in the length direction of the inner divided pressurizing portion 32b in the inner and outer directions, and the inner divided pressurizing portion 32b. Are covered by. Similarly, a gap 32b between adjacent ones of the inner divided pressurizing portions 32b.
₁ is opposed to the central position in the lengthwise direction of the outer divided pressing portion 32a in the inner and outer directions, and
Are covered by.

The width of the outer gap 32a ₁ and the inner gap 32
It is almost the same as the width of b _{1. When} this width is represented by w, it is preferable that the gap width w is narrower than the width of the lead 19.
In the case of a divided pressurizing section having a length of about mm, a width of 0.1 mm or more is sufficient in order to prevent adjacent divided pressurizing sections from interfering with each other due to temperature rise and causing warpage. is there. In the case of the present embodiment, since the outer gap 32a ₁ is covered by the inner split pressurizing portion 32b and the inner gap 32b ₁ is covered by the outer split pressurizing portion 32a, the lead 19 and the electrode 17 are separated from each other. There is no region where the contact portion is not crimped, and the upper limit of the gap width w need not be particularly limited, but in the case of the present embodiment, it is about 0.2 mm.

Incidentally, the respective divided pressurizing parts 32a, 3 which are separated from each other.
The shape of each 2b is preferably as close to a square as possible in consideration of warpage and deformation due to thermal strain. Original 1
A method of dividing a single plate into a plurality of parts to form a divided pressing part is to shave with a wire or melt with heat from an electron beam.

The depth d of the gaps 32a ₁ and 32b ₁ is smaller than the height h of the divided pressing portions 32a and 32b, but it is desirable that the depth d be as close to the height h as possible. This is because when brazing the pressurizing portion to the body material, warpage due to thermal strain of the divided pressurizing portion due to a difference in thermal expansion between the materials is reduced as much as possible. The depth d may be equal to the height h.

As shown in FIG. 4, after the inner lead bonding by the TAB method, a large number of external lead leads 19 are extended from the TAB package 18 in which resin is applied and the tape carrier film is punched.
The bonding tool 31 having the above-described configuration is provided with the outer ends of the large number of leads 19 and the large number of electrodes 1 on the circuit board 16.
7 and 7 are aligned and in contact with each other, and are integrally joined by heating and pressurizing.

The TAB package 18 is a high density / highly integrated circuit device having about 320 pins and a chip size of about 10
mm square. The area size for outer lead bonding of the lead 19 to the electrode 17 on the circuit board 16 is about 20 mm square. The pitch of the electrodes 17 and the leads 19 on the circuit board 16 is 200 to 250 μm, the lead width is about 80 μm, and the lead thickness is about 30 μm. The lead 19 is made of Cu, the surface of which is plated with Sn, and the surface of the electrode 17 is plated with Au.

The circuit board 1 is mounted on the bonding stage 15.
6 is placed in the positioning state, and the bonding stage 15
It is preheated by the heater 23 built in the. With respect to the circuit board 16, the TAB package 18 is aligned with the electrodes 17 of the circuit board 16 and the external leads 19 of the TAB package 18.
Is placed. Then, the bonding tool 31 is heated by an internal heater 24 and then lowered, and the divided pressing portions 3 arranged in a square and staggered manner in two rows inside and outside of the tip portion thereof.
A large number of leads 19 and electrodes 17 that are in contact with each other are collectively bonded (joined) by 2a and 32b.

As the bonding conditions, for example, the temperature of the bonding tool 31 is set to about 400 ° C., and 50 g weight per lead is heated and pressed for 3.0 seconds. Sn plating of lead 19 and A of electrode 17
The u plating melts and forms a eutectic alloy for connection.

In the case of the present embodiment, since the pressurizing portions of each row are divided pressurizing portions 32a and 32b and the lengths of the individual pressurizing portions are shortened, warping at high temperature can be prevented. . Not only that, the gap 32a ₁ of the outer divided pressurizing portion 32a is covered by the inner divided pressurizing portion 32b, and the gap 32b ₁ of the inner divided pressurizing portion 32b is covered by the outer divided pressurizing portion 3b.
Since it is covered with 2a, the lead pitch and the lead width have been reduced and the number of leads has been increased as the density and integration of the TAB package 18 have increased. A sufficient pressure can be applied to the electrode 17. That is, it is possible to eliminate the occurrence of a defective connection area between the lead 19 and the electrode 17 on each side, and to collectively connect all the leads with high connection reliability.

Further, in the lead connection structure 100 shown in FIG. 4 manufactured in this way, as can be seen from FIG. 3, the connection position of the lead 19 to the electrode 17 in the lead longitudinal direction (indicated by a small black circle). However, the arrangement is not at the same position (more specifically, the adjacent leads are alternately arranged back and forth, and the arrangement is staggered as a whole). However, the state of connection is uniform at all connection points, and it is possible to improve the reliability of connection of all leads to the electrodes on the circuit board. Further, since the yield is good, it is possible to reduce the manufacturing cost of the lead connection structure 100.

The present invention is not limited to the above embodiment. In the above-mentioned embodiment, the number of rows of the divided pressing portions on each side is two, but the number of rows may be three or more.
However, the structure is the simplest in the case of two rows. In the above embodiment, the outer row is divided into four and the inner row is divided into three.
The number of divisions may be two or more. Further, it is not always necessary that the divided pressurizing portions 32a and 32b be equally divided.
The position of the gap may be any position as long as it is covered, and may be deviated from the center of the opposing divided pressing portion. In the above embodiment, the material of the body material 34 and the divided pressure portions 32a, 32b are different, but instead of this, the body material 34 and the divided pressure portions 32a, 32b may be made of the same material. It may be integrally molded. Since the connecting points between the leads 19 and the electrodes 17 may be staggered in some cases, it is possible to deal with the case where the electrodes 17 are arranged in a staggered manner on the circuit board 16. Further, in the above embodiment, the bonding tool used in the outer lead bonding process of the TAB method has been described, but it goes without saying that the present invention may be applied to a similar bonding tool for lead connection such as a resin mold package.

Further, although the constant heat type bonding tool has been described in the above embodiment, it is needless to say that the present invention may be applied to another heating type pulse heating type bonding tool.

[0040]

According to the bonding tool of the first aspect of the present invention, since the pressurizing portion is divided in each row and the length of each divided pressurizing portion is shortened, the warping at high temperature is prevented. In addition to being able to prevent, since the gap in the outer split pressurizing section is covered by the inner split pressurizing section, and the gap in the inner split pressurizing section is covered by the outer split pressurizing section, All leads will be pressed by one of the divided pressure parts, regardless of the lead pitch, lead width reduction and multiple leads accompanying the high density and high integration of electronic components such as semiconductor chips. It is possible to eliminate a region where a poor connection between the lead and the electrode occurs on each side and to collectively connect all the leads with high connection reliability. Therefore, the yield of bonding is improved, it is not necessary to correct the inclination of the pressurizing portion due to thermal strain when the temperature of the bonding tool is raised, and the work efficiency can be improved.

According to the bonding tool of the second aspect of the present invention, the simplest structure can be achieved while satisfying both the prevention of warpage and the collective connection of all leads, and the connection state of all connection points is uniform. Can be converted.

According to the lead connection structure of the third and fourth aspects of the present invention, since the electronic component such as the semiconductor chip having a high density and high integration is mounted, the lead pitch,
Even though the lead width is reduced and the number of leads is increased, it is possible to improve the connection reliability with the electrodes on the circuit board for all the leads. Further, since the yield is good, the cost can be reduced.

[Brief description of drawings]

FIG. 1 (a) is a perspective view of a bonding tool according to an embodiment of the present invention when an array of pressure portions at a tip end portion is viewed upside down, and FIG. 1 (b) is a view (a). FIG. 3C is a plan view showing the arrangement of the pressing portions in this state, and FIG. 6C is a schematic front view of the lower portion when the bonding tool is in the normal posture.

FIG. 2 is a schematic front view of a main part showing a state during a bonding operation in the example.

FIG. 3 is a plan view of an essential part showing a bonding state corresponding to FIG. 2 on only one side.

FIG. 4 is a schematic perspective view of a lead connection structure manufactured by a bonding tool according to an exemplary embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating an outer lead bonding process in a conventional example.

FIG. 6A is a half sectional view showing a schematic structure of a bonding tool of a conventional example, and FIG. 6B is a plan view showing an upside down shape of a one-letter type pressurizing portion formed at a tip portion thereof.
(C) is a plan view showing a form of a pressurizing portion obtained by equally dividing a one-character type.

FIG. 7 is a schematic front view showing a state where a lead and an electrode on a circuit board cannot be satisfactorily connected when a bonding tool for outer lead bonding in a conventional example is used.

[Explanation of symbols]

15 ... Bonding stage 16 ... Circuit board 17 ... Electrode 18 ... TAB package 19 ... External lead 20 ... Semiconductor chip 31 ... Bonding tool 32a. Part 32a ₁ ... Gap between outer split pressurizing parts 32b ... Inner split pressurizing part 32b ₁ ... Gap between inner split pressurizing parts 33 ... Brazing material 34 ... Body material 100 ... Lead connection structure

Claims (4)

[Claims] 1. A bonding tool for integrally bonding a large number of leads extending from an electronic component and a large number of electrodes on a circuit board, wherein at least two rows are provided on each side of the tip of the body material. In each of the rows, a plurality of divided pressure portions are integrally fixed, and the rows of the divided pressure portions of two or more rows are located inside a part of the divided pressure portions located outside and inside. A part of the divided pressurizing portion is overlapped in the inner and outer directions, and a gap between adjacent outer pressurizing portions is arranged so as to face the inner divided pressurizing portion in the inner and outer directions. Characteristic bonding tool. 2. The rows of the inner and outer divided pressure portions are two rows, the divided pressure portions of each row are equally divided and have substantially equal lengths, and the gap between the outer divided pressure portions is inside. The bonding tool according to claim 1, wherein the split pressing portion is located substantially at the center in the length direction. 3. A lead connection structure manufactured by the bonding tool according to claim 1 or 2.
A large number of leads extended from the electronic component and a large number of electrodes on the circuit board are contacted and bonded to each other, and the connection positions of the leads to the electrodes in the lead longitudinal direction are not the same position. Lead connection structure. 4. The lead connection according to claim 3, wherein the connection positions of the leads with respect to the electrodes in the longitudinal direction of the lead are alternately arranged in front and back for each adjacent lead to form a staggered arrangement as a whole. Structure.