JPH1068966A - Thermocompression bonding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermocompression bonding apparatus for pressing a long heater tool heated by a pulse heating method onto a work having a thermocompression bonding area shorter than the heater tool and thermocompression bonding the work. The portion not in contact with the heater (non-contact portion) is prevented from overheating and damaging the heater tool. SOLUTION: Two intermediate terminals which come into contact with a heater tool near both ends of a thermocompression bonding area of a work are provided, and end electrodes of the heater tool are connected to respective intermediate terminals close to these electrodes, respectively. The current flowing in the direction is divided by the intermediate terminal at a portion of the heater tool that is not in contact with the workpiece. A large number of intermediate terminals may be fixed to the heater tool in advance, and the intermediate terminals used may be changed according to the size of the work. If there is a non-thermocompression area in the middle of the heater tool, the intermediate terminals may be connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocompression bonding apparatus used to press a long heater tool against a work and heat the work by a pulse heating method to thermocompress the work.

[0002]

2. Description of the Related Art Conventionally, ultra-high-density packaging technology has been developed as electronic devices become smaller, lighter and thinner. For example, when connecting a terminal of a liquid crystal panel or the like to a connection terminal of an external circuit, the distance between the connection terminals is required to be further reduced, and the pitch of the connection terminals is 0.2 to 0.5 mm or finer. Is required. As one of means for connecting a lead wire to such a fine connection terminal, a method using an anisotropic conductive film is known.

The anisotropic conductive film is a polymer film formed by uniformly dispersing conductive particles in an adhesive such as a resin, and has an electric anisotropy. In other words, the conductive particles are brought into contact only in the thickness direction of the film by conducting the thermal compression by sandwiching them between the protruding electrodes, thereby obtaining conductivity, obtaining conductivity between the upper and lower electrodes, and insulating in the other directions. It is something that can be given.

Since the anisotropic conductive film can be mounted at a relatively low temperature, it is frequently used for connecting a liquid crystal panel having a low allowable temperature to a flexible wiring board. When performing thermocompression bonding between electrodes, for example, between a terminal and a lead wire using an anisotropic conductive film having such characteristics, in order to obtain stable electrical characteristics and adhesive strength, a predetermined pressing force, a predetermined pressure It is important that the heating temperature is applied uniformly to the connection surface.

For this reason, conventionally, a plate-shaped jig is mounted on a heater block controlled at a predetermined temperature, and a liquid crystal display panel, an anisotropic conductive film and a flexible printed wiring board (FPWB) are sequentially stacked on the jig. In addition, a thermocompression bonding device that presses a long heater tool having a length of a compression portion from above is used. Here the heater block is about 100 ° C
The heater tool is heated to 300 to 400 ° C. by supplying a pulsed current at a predetermined cycle (pulse heat bonding method). After the heater tool is held at this temperature for a predetermined time (about 30 seconds), the heater tool is separated from the workpiece after the heater tool has cooled. The heating time and the heating temperature vary depending on the target work.

[0006] The heater tool used here needs to have its temperature sufficiently raised quickly by supplying current, and to be quickly cooled by cutting off the current. For this reason, its heat capacity is made sufficiently small. The reason why the heater block and the jig are preliminarily heated is to eliminate the need to excessively increase the heating temperature of the heater tool and to improve the durability of the heater tool.

[0007] Solder plating is applied to the electrodes of the wiring board, and an IC lead or the like is placed on the electrode, a long heater tool is pressed from above, and the heater tool is heated by a pulse heating method to perform solder plating. Melting (reflow)
The method of soldering and soldering is also known.

[0008]

In the case of heating a work by pressing a long heater tool against the work as described above, the entire heating surface of the heater tool is evenly brought into contact with the work, and the heat is uniformly applied from the entire heater tool. It is necessary to escape the work.

The reason is that, when the heating area of the work is shorter than the length of the heater tool, a portion of the heater tool that is not in contact with the work (a non-contact portion) becomes hot. The reason why the temperature distribution of the heater tool becomes non-uniform is that heat does not escape from the non-contact portion to the work.

FIG. 8 is a diagram for explaining this problem. In this figure, reference numeral 1 denotes a long heater tool, which is made of a resistance heating material such as molybdenum, titanium, and tungsten.
The horizontal straight portion of the heater tool 1 is engaged and held from below in a groove provided on the lower edge of the plate-shaped ceramic block 2. The left and right edges of the heater tool 1 rise along the left and right edges of the ceramic block 2 and serve as electrodes, that is, the power supply blocks 3 and 3.

Therefore, when current flows from one of the power supply blocks 3 to the other, the entire heater tool 1 generates heat at the same time. The temperature is detected by a temperature sensor 4 such as a thermocouple attached near the center of the heater tool 1, and the current supplied to the heater tool 1 is controlled so that the detected temperature becomes constant.

In FIG. 8, 5 is a wiring board, and 6 is a work. The work 6 may be a laminate of the above-described anisotropic conductive film and a lead such as an IC superposed thereon. Also, a lead or the like mounted on a solder-plated electrode may be used.

As shown in FIG. 8, when the length of the work 6 is shorter than that of the heater tool 1, the heat of the heater tool 1 only escapes to the work 6 in the contact portion with the work 6, ie, in the thermocompression bonding area A. Instead, the temperature of this portion A is detected by the sensor 4 and the heater current is managed. Therefore, the temperature of the contact portion A does not rise excessively. However, since the heat of the heater tool 1 does not escape from the portion B that is not in contact with the work 6 (the non-contact portion, that is, the non-thermocompression region), the temperature becomes high.

Usually, the heater tool 1 is managed so that the temperature detected by the sensor 4 is 300 to 480 ° C.
When the non-contact portion B is located far from the sensor 4, the non-contact portion B is 100 to 13
0 ° C or higher temperature. Therefore sensor 4
When the set temperature is high, or when the position or the size of the non-contact portion B is inappropriate, the non-contact portion B becomes hotter as it becomes red hot, causing a problem that the heater tool 1 is significantly damaged.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a thermocompression bonding apparatus in which a portion of a heater tool that is not in contact with a workpiece (a non-contact portion) does not overheat and may damage the heater tool. The purpose is to provide.

[0016]

SUMMARY OF THE INVENTION According to the present invention, there is provided a thermocompression bonding apparatus which presses a long heater tool heated by a pulse heating method onto a work having a thermocompression bonding area shorter than the heater tool, and thermocompression-bonds the work. 2 connected to the heater tool near both ends of the thermocompression bonding area of the work.
Two intermediate terminals, the end electrodes of the heater tool are connected to the respective intermediate terminals near these electrodes, and the current flowing in the longitudinal direction of the heater tool is supplied to the non-contact portion of the heater tool with the workpiece. The thermocompression bonding apparatus is characterized in that the flow is divided by the intermediate terminal.

Here, it is desirable that the positions of the contacts can be changed so that their fixed positions can be changed according to the length of the thermocompression bonding portion of the work.

The same object is also achieved in a thermocompression bonding apparatus for pressing a long heater tool heated by a pulse heating method on a work having a thermocompression bonding area shorter than the heater tool and thermocompression bonding the work. Currents flowing in the non-thermocompression bonding area of the heater tool by providing three or more intermediate terminals at different positions in the longitudinal direction of the heater tool and selectively connecting the end electrodes of the heater tool and the intermediate terminals with a wiring cord. To the wiring cord of the intermediate terminal.

Here, a pair of intermediate terminals, for example, a pair of intermediate terminals close to the end of the non-thermocompression bonding area, can be connected to end electrodes near each intermediate terminal by a wiring cord. If the thermocompression bonding area is divided into two or more places, two intermediate terminals near the end of the non-thermocompression bonding area located between the thermocompression bonding areas may be connected by a wiring cord. It is desirable that the intermediate terminal be fixed to the heater tool by welding because the contact resistance is reduced.

[0020]

FIG. 1 is a perspective view showing a thermocompression bonding apparatus according to a first embodiment of the present invention, FIG. 2 is a side sectional view of a portion including an intermediate terminal of a crimping portion, and FIG. FIG. 4 is a diagram showing a current path.

In FIG. 1, reference numeral 10 denotes an XY moving table which can be moved in both X and Y directions on a horizontal plane.
Reference numeral 12 denotes a heater block mounted on the table 10. The heater block 12 is a thick plate made of metal, and a heat insulating plate 14 made of aramid resin or the like is adhered to a lower surface thereof, and the heat insulating plate 14 is in close contact with the table 10.

A small hole penetrating in the left-right direction is formed in the heater block 12, and an electric heater 16 (only one is shown) is inserted into the small hole from both left and right sides. Heater 16
Is supplied with a current from a heater power supply circuit (not shown) to heat the heater block 12 and maintain it at about 100 ° C.

Reference numeral 18 denotes a plate-shaped jig which is mounted on the upper surface of the heater block 12. The jig 18 is made of an aluminum plate or the like, and is heated by the heater block 12.

Reference numeral 26 denotes a wiring board, in which a liquid crystal display panel is used. On the upper surface of the substrate 26, a large number of electrodes long in the front-rear direction have a small pitch (about 0.2 mm = 200 μm) in the horizontal direction (the length direction of the electric heater 16).
They are formed side by side at intervals. The substrate 26 may be a rigid insulating substrate such as a phenol resin or a glass epoxy resin or a flexible insulating substrate such as a polyimide resin or a polyester resin instead of the liquid crystal panel.

Reference numeral 28 denotes an anisotropic conductive film cut in a tape shape, and is adhered on the electrodes of the substrate 26 along the parallel direction of a large number of electrodes. On the anisotropic conductive film 28, an object 30 is further placed. In this case, the object to be pressed 30 is a lead for driving LSI or IC of the liquid crystal panel, and these leads are connected to the substrate 2 with the anisotropic conductive film 28 interposed therebetween.
6 corresponding electrodes.

It is a matter of course that the object to be pressed 30 may be an electrode such as a flexible wiring board instead of an LSI or an IC lead. The electrodes, the anisotropic conductive film 28 and the object 30 are located above the heater 16 along the length direction of the heater 16. In this embodiment, a laminate of the substrate 26, the anisotropic conductive film 28, and the object 30 to be compressed is a work 31 to be subjected to thermocompression bonding.

Reference numeral 32 denotes a pressure bonding head, which is a head holding unit 3
4 so as to be able to move up and down. This crimping head 32
Has a horizontal and long block-shaped tool holder 36,
A pair of left and right guide rods 38, 38 vertically implanted in the tool holding portion 36 are held by the head holding portion 34 so as to be vertically movable. An air cylinder 40 is interposed between the tool holding portion 36 and the head holding portion 34, and the tool holding portion 36 can be moved up and down by the air cylinder 40.

As shown in FIG. 2, a plate-like holding block 42 made of stainless steel is suspended from the lower surface of the tool holding portion 36 by a coil spring (not shown) so as to be vertically movable. On the rear surface of the holding block 42, a plate-shaped ceramic block 44 made of black gabbro is closely fixed. That is, the ceramic block 44 is sandwiched between the holding block 42 and a bakelite holding block 46, and is fixed to the holding block 42 by a plurality of bolts 47 (FIG. 2).

The lower part of the ceramic block 44 projects downward like a tongue, and its lower edge is horizontal and has a groove 48 shown in FIG.
Are formed. A heater tool 50 having a rectangular cross section is engaged and held in the groove 48. The heater tool 50 is made of a high-resistance material such as molybdenum, titanium, tungsten, or Kovar, and has a shape that engages with the groove 48 of the ceramic block 44. That is, the center portion is straight and both ends are vertically bent so as to rise along both right and left edges of the ceramic block 44.

The lower surface of the central portion of the heater tool 50 becomes a flat crimping surface 50A, and this crimping surface 50A
1 longer than the crimping area. That is, it is longer than the length of the anisotropic conductive film 28. Power supply blocks 52, 52 insulated from the holding block 42 at both ends of the heater tool 50 (FIG. 3)
Is connected.

The heater tool 50 includes a wiring cord 5
A large pulse-like current is supplied from a power supply device (not shown) via the power supply block 4 and the power supply block 52, and the heater tool 50 is heated by this current. The heater tool 50
A temperature sensor such as a thermocouple is attached at an appropriate position, for example, near the center, and the temperature is controlled. For example, the vicinity of the center of the crimping surface 50A is controlled at about 300 to 400 ° C.

This crimping head 32 is provided with two intermediate terminals 56, 56 so as to be movable. These intermediate terminals 56, 56 are provided for shunting and reducing the current flowing in a part of the heater tool 50, that is, the non-contact portion B with the workpiece 31.

As shown in FIG. 2, a pair of left and right rail plates 58, 58 are fixed to the insulating holding block 46 on the back of the crimping head 32. The rail plates 58, 58 are horizontally long plates made of a good conductive metal, for example, chromium copper and chrome-plated.
0 and 60 are formed. Both rail plates 58, 58 are connected to power supply blocks 52, 52 by wiring cords 62, 62, respectively.
Connected by

The intermediate terminals 56, 56 are mounted on different rail plates 58, 58 so that the horizontal position can be changed. That is, the intermediate terminals 56, 56 are made of a material having elasticity and good conductivity, such as a material obtained by plating nickel and gold on copper.
8, 58 are screwed in contact with the rear surfaces.

The screw 64 used here passes through the upper part of the intermediate terminal 56 and the slot 60 and is screwed into the sliding piece 66 located on the back surface of the rail plate 58. Intermediate terminal 56
Is extended toward the lower edge of the ceramic block 44 and pressed against the side surface (rear surface) of the heater tool 50. The lower part of the intermediate terminal 56 is divided into two parts (see FIG. 3).
), The contact pressure with the heater tool 50 is increased.

Accordingly, when the screw 64 is loosened, the screw 64 can move in the slot 60 together with the intermediate terminal 56 and the sliding piece 66. The intermediate terminal 56 is connected to the heater tool 50.
Are positioned near the boundary between a portion (contact portion) A that comes into contact with the work 31 and a non-contact portion B, and are fixed by screws 64.

The flow of the current I in this case is as shown in FIG. When the current I is supplied to the heater tool 50, a part I of the current I is supplied to one power supply block 52A.
₁ is diverted to the contact 56A. Therefore, the current flowing through the non-contact portion B1 of the heater tool 50 is reduced to (II- ₁ ).

Here, if the resistance value of the non-contact portion B1 of the heater tool 50 is R1, and the resistance value of the shunt circuit including the intermediate terminal 56A and the wiring cord 62 is r1, I ₁ = [R ₁ / (R
_{1 + r 1)] × I} , (I-I 1) = [r 1 / (R 1 + r 1)]
× I. In general, since R ₁ >> r ₁ , (II ₁ )
Becomes extremely small. For this reason, the calorific value of the non-contact portion B1 decreases, and there is no overheating. Work 31
Since the entire supply current I from the power supply flows through the contact portion A that contacts the contact portion, the contact portion A is sufficiently heated and reaches a predetermined temperature.

[0039] are exactly the same as any other of the non-contact portion B2, it is diverted to the shunt circuit current I ₂ is made of the intermediate terminal 56B and the wiring cord 62B. Therefore, overheating of the non-contact portion B2 is also prevented.

When using this crimping device, the jig 18 is placed on the heater block 12 on the XY moving table 10, and the electric heater 16 of the heater block 12 is energized to reduce the surface temperature of the jig 18 to about 100 ° C. To keep. A work, that is, a work 31 which is a laminate of the substrate 26, the anisotropic conductive film 28, and the material to be pressed 30 is placed thereon. And table 10
Is moved to position the press-bonded portion of the work below the press-bonded surface 50A of the heater tool 50 (the state of FIG. 3).

In this state, the pressure bonding head 32 is lowered by the air cylinder 40, and the pressure bonding surface 50A of the heater tool 50 is moved.
Is pressed against the work. When a pulse current is applied to the heater tool 50, the heater tool 50 generates heat. At this time, the heater tool 50 contacts the work 31 shorter than this. The current I, which is the same as the current I supplied from the power supply, flows through the contact portion A with the work 31, but a smaller current (I− I ₁ ) and (I−I ₂ ) flow.

Therefore, the temperature of the non-contact portion B (B1, B2) does not rise too much. This heater tool 5
The temperature of 0 is detected by a temperature sensor attached to the contact portion A, and the magnitude of the current or the duty ratio of the pulse is controlled so that the temperature becomes a preset temperature within a range of 300 to 400 ° C.

The portion of the heater tool 50 which is in contact with the work 31 as shown by a broken line in FIG.
It flows through the jig 18 and the heater block 12 through (26, 28, 30), and at this time, the anisotropic conductive film 28 is heated to a predetermined temperature (target temperature ± 10 ° C.). As a result, the conductive particles in the anisotropic conductive film 28 sandwiched between the electrode and the lead come into contact, and the conductivity between the electrode and the lead is obtained.

After the heating is continued for about 30 seconds, the energization of the heater tool 50 is stopped. Therefore, the heat of the heater tool 50 is released to the jig 18 and the heater block 12, and the work 31 (26, 28, 30) cools down rapidly.
The work 31 (26, 28, 30) cools, and after the resin in the anisotropic conductive film 28 solidifies, the pressure bonding head 32 is raised,
The heater tool 50 may be separated from the work 31 (26, 28, 30).

[0045]

Second Embodiment FIG. 5 is a front view showing a second embodiment of the pressure bonding head. In this embodiment, the heater tool 50 and the intermediate terminals 156 (156A, 156B) are fixed by welding. In the figure, reference numeral 100 denotes a welding location.

Generally, the heater tool 50 is instantaneously moved from 300 to
To heat to 400 ° C., the heater tool 50
A large current of about A needs to flow. On the other hand, in the first embodiment, since the intermediate terminal 56 is brought into contact with the heater tool 50 by utilizing its elasticity, the contact resistance of the contact portion becomes large, and the amount of heat generated when a large current flows is large. Overheating and the durability may be reduced.

In the second embodiment, the intermediate terminal 156
The contact resistance between the heater 100 and the heater tool 50 is reduced by fixing the connection 100 by welding. The overheating due to the heat generated at the welded portion 100 is prevented, and the durability is improved. In this case, the intermediate terminal 156 is welded in advance corresponding to the length of the thermocompression bonding area A of the work.

[0048]

Third Embodiment FIG. 6 is a front view showing a third embodiment of the pressure bonding head. In this embodiment, a large number of intermediate terminals 256 are welded or detachably fixed to the heater tool 50 at appropriate intervals in advance.

In the second embodiment (FIG. 5), since the two intermediate terminals 156 and 156 are welded, there is a problem that a different crimping head must be used if the size of the work is different. The third embodiment has a large number of intermediate terminals 256.
Are provided in advance, and the intermediate terminals 256A and 256B corresponding to the vicinity of the end of the dimension of the work (the dimension of the thermocompression bonding area A) are connected to the terminal electrodes 52 and 52 by the wiring cord 62, respectively.

As a result, works having different dimensions can be easily handled by changing the intermediate terminal 256 for connecting the wiring cord 62. That is, it is possible to improve the durability of the heater tool 50 while preventing the contact portion between the intermediate terminal 256 and the heater tool 50 from overheating, and to easily cope with a dimensional change of the work.

[0051]

Fourth Embodiment FIG. 7 is a front view showing a fourth embodiment of the pressure bonding head. In this embodiment, the thermocompression bonding area A of the workpiece is used.
In the case where a plurality of heater tools 50 are provided, overheating of the non-thermocompression bonding area B ₀ located at an intermediate position of the heater tool 50 is prevented. That intermediate terminals 3 provided in the vicinity of both ends of the non-thermal compression region B ₀
56A and 356B are connected by a wiring cord 62. In this embodiment, since the non-thermocompression bonding areas B and B are also provided near both ends of the heater tool 50, the currents in these areas B and B are divided by providing the intermediate terminals 356C and 356D.

The present invention can be used not only for thermocompression bonding using the anisotropic conductive film 28 but also for other thermocompression bonding. For example, the present invention can also be applied to a method in which a predetermined amount of solder is supplied to electrodes in advance by solder plating or the like, and the electrodes are reflowed by heating with a heater tool.

[0053]

As described above, according to the first aspect of the present invention, two intermediate terminals that contact the heater tool are provided near both ends of the thermocompression bonding area of the work, and the current flowing through the portion of the heater tool that does not contact the work is provided. Since the flow is diverted through the intermediate terminal, there is no possibility that the portion of the heater tool that does not contact the work is overheated and the heater tool is damaged.

Here, if the intermediate terminal is provided so that the mounting position can be changed, it is possible to cope with a change in the size and position of the work only by changing the position of the intermediate terminal.

According to a third aspect of the present invention, three or more intermediate terminals are provided in the longitudinal direction of the heater tool, and any one of the intermediate terminals is connected to an end electrode by a wiring cord (claim 4).
Alternatively, the intermediate terminals are connected to each other by a wiring cord (claim 5), so that the current flowing in the non-thermocompression bonding area is diverted to the wiring cord and the intermediate terminal. It can be easily handled by changing the intermediate terminal for connecting the cord. Therefore, it is not necessary to prepare a separate pressure bonding head for each work having different dimensions.

Here, if the intermediate terminal is fixed to the heater tool by welding, the contact resistance of the intermediate terminal is reduced, and the amount of heat generated at this connection portion is reduced, so that the intermediate terminal can be reliably prevented from overheating. Item 6).

[Brief description of the drawings]

FIG. 1 is a perspective view showing a thermocompression bonding apparatus according to the present invention.

FIG. 2 is a side sectional view of a portion including a contact of a crimping portion.

FIG. 3 is a front view of the vicinity of a pressure bonding head.

FIG. 4 is a diagram showing the current path;

FIG. 5 is a front view of a second embodiment of the crimping head.

FIG. 6 is a front view of a third embodiment of the crimping head.

FIG. 7 is a front view of a fourth embodiment of the crimping head.

FIG. 8 is a front view showing a conventional pressure bonding head.

[Explanation of symbols]

31 Work 32 Crimping Head 50 Heater Tool 52 Power Supply Block 56 as End Electrode 56, 156, 156, 356 Intermediate Terminal 62 Wiring Code 100 Welding A Contact Part (Heat Compression Area) B, B ₀ Non-Contact Part (Non-thermocompression Area) )

Claims (6)

[Claims] 1. A thermocompression bonding apparatus for pressing a long heater tool heated by a pulse heating method onto a work having a thermocompression bonding area shorter than the heater tool and thermocompression bonding the work, wherein both ends of the thermocompression bonding area of the work are provided. Providing two intermediate terminals connected to the heater tool in the vicinity, connecting the end electrodes of the heater tool to the respective intermediate terminals close to these electrodes, and flowing the current flowing in the longitudinal direction of the heater tool, A thermocompression bonding apparatus, wherein a flow is divided by the intermediate terminal at a portion of the heater tool that is not in contact with the work. 2. The intermediate terminal is changeable in position.
Thermocompression bonding equipment. 3. A thermocompression bonding apparatus that presses a long heater tool heated by a pulse heating method onto a work having a thermocompression bonding area shorter than the heater tool and thermocompression-bonds the work. By providing three or more intermediate terminals at different positions and selectively connecting an end electrode of the heater tool and the intermediate terminal with a wiring cord, a current flowing through a non-thermocompression bonding area of the heater tool is supplied to the intermediate terminal. A thermocompression bonding device, wherein the thermocompression bonding device divides the flow into a wiring cord. 4. The thermocompression bonding apparatus according to claim 3, wherein the pair of intermediate terminals are respectively connected to end electrodes near the respective intermediate terminals. 5. The thermocompression bonding apparatus according to claim 3, wherein two intermediate terminals are connected. 6. The thermocompression bonding apparatus according to claim 1, wherein the intermediate terminal is fixed to the heater tool by welding.