JP3361583B2 - Semiconductor element connection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a semiconductor element on a substrate, and more particularly to a connection method with which high accuracy can be obtained.

[0002]

2. Description of the Related Art The technique of connecting a semiconductor element to a substrate using an anisotropic conductive adhesive sheet has been widely used in recent years because the connection of narrow-pitch electrodes can be easily obtained only by applying heat and pressure. . In particular, the connection of the driving LSI to the liquid crystal panel in the liquid crystal display device is a connection between the transparent electrodes and the dissimilar materials such as metal. Therefore, there is a method of thermocompression bonding the tape carrier to which the LSI is bonded using an anisotropic conductive adhesive sheet. It is common. Next, a conventional method of connecting a liquid crystal panel and a drive LSI will be described with reference to the drawings.

A drive LSI is a so-called tape carrier package (hereinafter referred to as "T-carrier package") in which a semiconductor chip is bonded to a copper foil lead formed on a film tape such as polyimide.
The shape of (abbreviated as CP) is used. As shown in FIG. 9, after the anisotropic conductive adhesive sheet 22 is temporarily fixed on the terminals 21 of the liquid crystal panel 20, the terminals of the TCP 23 and the liquid crystal panel terminals are aligned and the adhesive property of the anisotropic conductive adhesive sheet 22 is adjusted. Use to temporarily fix. Since a plurality of TCPs 23 are normally connected to one side of the liquid crystal panel, this process is repeated for each TCP 23. Since it takes a certain amount of time for the anisotropic conductive adhesive sheet 22 to be thermoset, the production amount per hour is increased. Therefore, at least one side of the TCP 23 is thermocompressed at the same time without performing the thermocompression bonding process for each TCP 23. This is because the process is performed.

Next, as shown in FIG. 10, the liquid crystal panel 20 is placed on the stage, and the TCP2 is applied by the high temperature pressurizing device 25.
3 by applying pressure and heat to the anisotropic conductive adhesive sheet 22 by applying pressure on the terminals of the anisotropic conductive adhesive sheet 22.
With the conductive particles inside being sandwiched between both electrodes of the liquid crystal panel 20 and the TCP 23, the adhesive cures and a mechanical and electrical connection is obtained.

In recent years, the liquid crystal panel has been rapidly increasing in display pixel density, and along with it, the pitch of the connection terminal electrodes with the drive LSI has been narrowed. In particular, as the pixel density has tripled due to the colorization of the display, the terminal electrode pitch has become 1/3, and the demand for the connection position accuracy between the liquid crystal panel terminal and the TCP terminal has been remarkably increased.

[0006]

Regarding the accuracy of the interconnection position between the liquid crystal panel and the driving TCP, the above-mentioned conventional method places the liquid crystal panel on the stage and presses the TCP terminal with a high temperature pressurizing device. It was found that a theoretical positional shift occurs in the process of curing the adhesive in the anisotropic conductive adhesive sheet. This mechanism will be described with reference to the drawings.

FIG. 11A shows a state in which the TCP 23 is aligned with the electrodes of the liquid crystal panel terminal 21 and then temporarily fixed by utilizing the adhesive force of the anisotropic conductive adhesive sheet 22. In this state, the positions of both the TCP electrode 26 and the liquid crystal panel electrode 27 are aligned, ignoring errors in material processing. In FIG. 11B, after the liquid crystal panel 20 is fixed on the stage, the high temperature pressurizing device 25 descends from above and TCP 23
It was the moment I came into contact with. After that, the heat of the pressurizing device is conducted to the liquid crystal panel 20 and the temperature of the liquid crystal panel 20 is gradually raised. Further, the pressure of the pressurizing device is lowered in a short time by heat conduction, but is lowered because heat is supplied from the heater. The quantity is small. Figure 11
FIG. 11C shows a state after a certain time has elapsed from FIG. 11B, and the temperature of the liquid crystal panel 20 has changed due to thermal expansion. On the other hand, since the anisotropic conductive adhesive sheet 22 is softened and the friction coefficient between the TCP 23 and the liquid crystal panel 20 is lowered, slippage is likely to occur between the two, and the TCP 23 does not follow the dimensional change of the liquid crystal panel 20, rather. Pressurizing device 25
It closely adheres to and follows. As shown in FIG. 11D, the thermosetting of the anisotropic conductive adhesive sheet 22 is completed after a certain period of time, the liquid crystal panel 20 and the TCP 23 are fixed in the positional relationship of FIG. LCD panel 20 rising
Even if is cooled to room temperature, the positional relationship between the two does not change. The positional deviation amount of both terminals of the TCP 23 and the liquid crystal panel 20 is not significant because the size scale is small within one TCP 23, but the deviation amount is proportional to the thermocompression bonding size scale. Panel 20
This will cause a serious positional deviation on the entire one side of the terminal and cause connection failure.

Further, this phenomenon is not a block in which the pressurizing device is kept at a high temperature, but a metal block processed into a shape capable of directly applying an electric current. It occurs even in the case of the method. In this case, for the metal block, a metal having a very small coefficient of thermal expansion such as Super Invar is used to prevent thermal strain. Therefore, when the metal block generates heat and a certain amount of time elapses, the state becomes the same as that in FIG. 11C, and the positional deviation occurs.

As a method of solving this, there is a method of reducing the deviation by pressure-bonding TCP one by one, but the pressure-bonding time is T
It takes 15 to 20 seconds per CP, which is not practical because a large liquid crystal panel using a large number of TCPs requires a long process time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the conventional semiconductor element connecting method, and an object thereof is to provide a semiconductor element connecting method which fundamentally eliminates the positional deviation which occurs in principle during thermocompression bonding. is there.

[0011]

A method of connecting a semiconductor device according to the present invention comprises a step of temporarily fixing a semiconductor device to a substrate to be connected through an anisotropic conductive adhesive sheet, and the substrate to be connected is arranged on a smooth stage. After that, the semiconductor element is pressed by a pressing device and heated at the same time, and the pressing device is composed of a metal block that generates heat by a pulsed current, and the metal is the target of the thermocompression bonding step. It has a coefficient of thermal expansion that corresponds to the difference in temperature reached by the connection board and the pressurizing device so that the dimensional change values due to thermal expansion of the two substantially match. Alternatively, the pressurizing device is composed of a heating block held at a high temperature and a press-contact member that is in direct contact with the semiconductor element, and the press-contact member corresponds to a difference in temperature reached between the substrate to be connected and the press-contact member in the thermocompression bonding step. It has a coefficient of thermal expansion such that the dimensional change values due to the thermal expansion of are almost the same.

[0012]

In the present invention, the semiconductor device is temporarily pressed by the pressure device after the connected substrate on which the semiconductor device is temporarily fixed is placed on the stage via the anisotropic conductive adhesive sheet. Next, a pulsed current is applied to the metal block forming the pressurizing device to heat the pressurizing device for a certain period of time. Heat is conducted to the substrate to be connected through the semiconductor element and the anisotropic conductive adhesive sheet, and the temperature of the substrate rises to reach a certain temperature. At this time, the pressurizing device and the substrate to be connected undergo a dimensional change due to thermal expansion, and since heat is conducted to the substrate to be connected to the stage, a temperature difference occurs between the substrate and the pressurizing device and the substrate becomes lower in temperature. Let the thermal expansion coefficient of the metal block constituting the pressurizing device be α ₁ reaching temperature t ₁ , the thermal expansion coefficient of the substrate to be connected be α ₂ reaching temperature t _2, and the temperature of both before the pressure bonding work be t ₀ . . The dimensional change per unit length is expressed by (Equation 1) for the pressure device and (Equation 2) for the connected substrate.

[0013]

[Equation 1]

[0014]

[Equation 2]

At this time, the coefficient of thermal expansion of the metal block is set to α ₁
If is set to a value represented by (Equation 3), the amount of dimensional change between the pressurizing device and the connected substrate at the ultimate temperature is the same.

[0016]

[Equation 3]

Therefore, the relative position of the semiconductor element sandwiched between the two with respect to the substrate to be connected does not occur.

If the pressurizing device comprises a heating block kept at a high temperature and a press-contacting member that is in direct contact with the semiconductor element, the following steps are performed.

After the connection substrate to which the semiconductor element is temporarily fixed via the anisotropic conductive adhesive sheet is arranged on the stage, the pressure contact member of the pressure device presses the semiconductor element. Next, the heating block kept at a high temperature is brought close to or in close contact with the pressure contact member to heat the pressure contact member for a certain period of time. Heat is conducted to the substrate to be connected through the semiconductor element and the anisotropic conductive adhesive sheet, and the temperature of the substrate rises to reach a certain temperature. At this time, a dimensional change occurs due to thermal expansion in the pressure contact member of the pressure device and the substrate to be connected. Further, since heat is conducted to the stage of the substrate to be connected to the stage, a temperature difference occurs between the substrate and the pressure contact member, and the temperature of the substrate becomes lower. At this time, assuming that the thermal expansion coefficient of the pressure contact member is α ₁ attainment temperature t ₁ , the thermal expansion coefficient of the substrate to be connected is α ₂ attainment temperature t _2, and the temperature of both before the pressure bonding work is t ₀ , the same as the above description. By setting the thermal expansion coefficient α ₁ of the pressure contact member to a value represented by (Equation 3) by such a mechanism, the dimensional change between the pressure contact member and the substrate to be connected at the ultimate temperature is the same. Therefore, the relative position of the semiconductor element sandwiched between them with respect to the substrate to be connected does not change.

[0020]

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

FIG. 1 is a side view of an apparatus used in a semiconductor element connecting method according to an embodiment of the present invention. The pressurizing device 2 for press-bonding the semiconductor element to the substrate to be connected is one in which a block 5 made of molybdenum is processed into the shape shown in FIG. 2, and the press-contact surface 7 generates heat by passing an electric current in the direction of the arrow. As shown in FIG. 1, the entire pressurizing device 2 can be moved up and down by the air cylinder 4 to pressurize the terminal portion of the substrate to be connected placed on the stage 1.

In the present embodiment, the substrate to be connected is a glass substrate forming a liquid crystal panel, and the semiconductor element to be connected is an LSI mounted with a tape carrier package (TCP).

First, as shown in FIG. 3, the TCP 10 and the electrode pattern on the terminal 9 of the liquid crystal panel 8 were temporarily aligned with each other using the adhesive property of the anisotropic conductive adhesive sheet 11 in a state of being aligned.

Next, as shown in FIG. 4, the liquid crystal panel 8 is arranged so that the terminal 9 is directly below the pressure device 2 of the connecting device.
The TCP 10 on the liquid crystal panel terminal 9 is lowered by lowering the pressure device 2.
Was pressurized at a pressure of about 1.96 MPa. Next, pressurizing device 2
Is applied to the terminal 9 of the liquid crystal panel 8 for 20 seconds to raise the temperature.
Was heated. In this embodiment, the pressure device 2 is set to 2 before applying the current.
The temperature was 5 ° C., reached 250 ° C. 3 seconds after the current was applied, and was maintained at that temperature for almost 20 seconds. At this time, the liquid crystal panel terminal 1
The temperature of 1 rose from 25 ° C to 160 ° C. Next, when the current applied to the pressure device 2 is stopped and the air cylinder 4 is operated to raise the pressure device 2, the liquid crystal panel 8 is taken out of the stage 1 and the pressure-bonded portion is observed under a microscope. No positional deviation of the electrode pattern of TCP 10 was observed, and the connection was confirmed by electrical inspection.

In this embodiment, the substrate to be connected is a glass substrate and the coefficient of thermal expansion is about 8 × 10 ^-6 / K. The temperature before pressure bonding is 25 ° C. for both the pressure device and the glass substrate, and the temperature reached during pressure bonding is 250 ° C. for the pressure device and 160 ° C. for the glass substrate. Therefore, according to (Equation 3), the pressure device 2
The coefficient of thermal expansion required for is 4.8 × 10 ⁻⁶ / K.

Molybdenum used in the pressurizing device in this example has a coefficient of thermal expansion of about 4.8 × 10 ⁻⁶ / K, and is excellent in heat resistance and mechanical strength, and is suitable for this application. Is. However, the material that can be used for the pressurizer is not limited to molybdenum, but other materials such as nickel-iron alloy and tungsten whose coefficient of thermal expansion almost matches the above calculated value and whose heat resistance and mechanical strength can withstand this application. Then it can be used. Of course, each parameter used in the above calculation varies depending on the substrate, the connection device, and the connection temperature conditions, and therefore the calculated value of α ₁ also has a different value.

Next, another embodiment of the present invention will be described.

FIG. 5 is a side view of an apparatus used in the semiconductor element connecting method in this embodiment. As shown in FIG. 6, the pressurizing device for press-bonding the semiconductor element to the substrate to be connected is composed of a press-contact member 15 obtained by processing a block made of molybdenum and a vertically movable heating block 16. The heating block 16 has a structure in which a cylindrical heater 17 is embedded in a brass block. By detecting the temperature with a temperature sensor 19 and controlling the heater current, the heating block can be kept at a constant temperature. By the operation of 18, the heating block 16 is brought close to or in close contact with the press contact member 15, so that the press contact member can be heated to raise the temperature. The structure in which the heating block and the pressure contact member are separated in this way does not require a member that requires complicated and highly accurate processing such as the pressurizing device shown in FIG. 2 in the first embodiment, and does not require a power source for supplying a pulsed large current. There is an advantage that the temperature uniformity is high.
As shown in FIG. 5, the entire pressurizing device can be moved up and down by the air cylinder 4 to pressurize the terminal portion of the substrate to be connected placed on the stage 1.

In this embodiment, the substrate to be connected is a glass substrate forming a liquid crystal panel, and the semiconductor element to be connected is an LSI mounted with a tape carrier package (TCP).

First, as shown in FIG. 7, the TCP 10 and the electrode pattern on the terminal 11 of the liquid crystal panel 8 were temporarily aligned with each other using the adhesive property of the anisotropic conductive adhesive sheet 12 in a state of being aligned.

Next, as shown in FIG. 8, the terminals 9 of the liquid crystal panel 8 are arranged so as to be located directly below the pressure contact member 15 of the pressure device, and the operation of the air cylinder 14 causes the pressure contact member to descend, so that the liquid crystal panel terminal 11 is placed above. TCP10 of about 1.96 MPa
It was pressurized with the pressure of. Next, the heating block 16 kept at 265 ° C. is lowered by the operation of the air cylinder 18 to be brought into close contact with the pressure contact member 15, and the terminal 11 of the liquid crystal panel 8 is heated via the pressure contact member. In this embodiment, the pressure contact member 15 was at 25 ° C. before contact with the heating block, reached 250 ° C. after 5 seconds of contact, and maintained that temperature for about 20 seconds. At this time, the temperature of the liquid crystal panel terminal 9 rose from 25 ° C to 160 ° C. FIG. 8 shows a state where the heating block 16 is in close contact with the press contact member 15. Next, the heating block 16 is attached to the pressing member 15 by pressing.
After further separating, the pressure device is raised by the operation of the air cylinder 14, and then the liquid crystal panel 8 is taken out from the stage 1 and the pressure-bonded portion is observed with a microscope. The electrical inspection confirmed the connection.

In this embodiment, the substrate to be connected is a glass substrate and the coefficient of thermal expansion is about 8 × 10 ^-6 / K. The temperature before pressure bonding is 25 ° C. for both the pressure contact member and the glass substrate, and the temperature reached during pressure bonding is 250 ° C. for the pressure device and 160 ° C. for the glass substrate. Therefore, the thermal expansion coefficient required for the pressurizing device according to (Equation 3) is 4.8 × 10 ⁻⁶ / K.

The molybdenum used for the pressure contact member in this example has a coefficient of thermal expansion of about 4.8 × 10 ^-6 / K, and also has excellent heat resistance and mechanical strength, and is suitable for this application. is there. However, the material that can be used for the pressurizer is not limited to molybdenum, but other materials such as nickel-iron alloy and tungsten whose coefficient of thermal expansion almost matches the above calculated value and whose heat resistance and mechanical strength can withstand this application. Then it can be used.

[0034]

As is apparent from the above description,
The semiconductor element connection method of the present invention is a thermocompression bonding method using an anisotropic conductive adhesive sheet, but fundamentally eliminates the positional deviation that occurs in principle during thermocompression bonding, and requires highly accurate connection. It is possible to manufacture a color liquid crystal panel having a high display pixel density.

Further, the present invention can be widely applied not only to liquid crystal panels but also to a connection construction method using an anisotropic conductive adhesive sheet, and it is of great industrial value that a very high positional accuracy can be easily obtained.

[Brief description of drawings]

FIG. 1 is a side view of a semiconductor element connecting device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a pressure device of the same semiconductor element connecting device as above.

FIG. 3 is a perspective view of one step of the semiconductor element connecting step of the same.

FIG. 4 is a side view of one step of the semiconductor element connecting step of the same.

FIG. 5 is a side view of a semiconductor element connecting device according to another embodiment of the present invention.

FIG. 6 is a side view of a pressure device of the semiconductor element connecting device of the same as above.

FIG. 7 is a perspective view showing a step of connecting the semiconductor elements in the same as above.

FIG. 8 is a side view of one step of the semiconductor element connecting step of the same.

FIG. 9 is a perspective view of a liquid crystal panel in a conventional example.

FIG. 10 is a side view of one process of the thermocompression bonding process.

11 (a) is a sectional view of the liquid crystal panel of the same as above, FIG.
Is a sectional view of the same liquid crystal panel, (c) is a sectional view of the same liquid crystal panel, and (d) is a sectional view of the same liquid crystal panel.

[Explanation of symbols]

1 Stage 2 Pressurizing Device 3 Basic Frame 4 Air Cylinder 5 Metal Block 6 Temperature Sensor 7 Pressure Contact Surface 8 Liquid Crystal Panel 9 Liquid Crystal Panel Terminal 10 Tape Carrier Package (TCP) 11 Anisotropic Conductive Adhesive Sheet 12 Semiconductor Chip 13 Stage 14 Air Cylinder 15 Pressure Contact Member 16 Heating Block 17 Cylindrical Heater 18 Air Cylinder 19 Temperature Sensor 20 Liquid Crystal Panel 21 Terminal 22 Anisotropic Conductive Adhesive Sheet 23 Tape Carrier Package (TCP) 24 Semiconductor Chip 25 Pressurizing Device 26 TCP Electrode 27 Liquid Crystal Panel Electrode

Claims (2)

(57) [Claims] 1. A step of temporarily fixing a semiconductor element to a substrate to be connected through an anisotropic conductive adhesive sheet, and placing the substrate to be connected on a stage and then pressurizing the semiconductor element by a pressurizing device to simultaneously heat the semiconductor element. And a thermocompression bonding step, wherein the pressurizing device is a metal block that generates heat with a pulsed current, and the metal corresponds to a difference in temperature reached between the connected substrate and the pressurizing device in the thermocompression bonding process. A semiconductor element connecting method, which has a coefficient of thermal expansion such that the dimensional change values due to the thermal expansion of are substantially the same. 2. A step of temporarily fixing a semiconductor element to a connection substrate through an anisotropic conductive adhesive sheet, and a step of placing the connection substrate on a stage and then pressing the semiconductor element by a pressure device to simultaneously heat the semiconductor element. A thermocompression bonding step, wherein the pressing device has a heating block held at a high temperature and a pressure contact member that is in direct contact with the semiconductor element, and the pressure contact member has the connection substrate and the pressure contact member in the thermocompression bonding step. A semiconductor element connecting method characterized by having a coefficient of thermal expansion such that the dimensional change values due to the thermal expansion of both of them substantially correspond to each other in the reached temperature difference.