JPH11204591A - Thermocompression bonding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermocompression bonding apparatus which is able to maintain flatness of a state at the thermocompression bonding, possibly minimize the temp. difference between the stage and a pressing head, and execute a thermocompression bonding with high-connection reliability. SOLUTION: A thermocompressin bonding apparatus for mutually thermocomprssion-bonding at least two works to be thermocompression-bonded (e.g. semiconductor chip 2 and circuit board 3) via an adhesive film such as anisotropically conductive adhesive film 1 has a stage A for mounting the works and a pressing head B for pressing the works mounted on the stage A. A surface of the stage A contacting the works is constituted of a ceramic heater 4.

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 for thermocompression bonding at least two objects to be thermocompression-bonded via an adhesive film, particularly a thermosetting anisotropic conductive adhesive film.

[0002]

2. Description of the Related Art In a case where an ITO electrode of a liquid crystal panel is bonded to an electrode of an FPC, or a case where a semiconductor chip is flip-chip mounted on a multi-chip module substrate, thermosetting is performed between them (the object to be thermally compressed). Thermocompression bonding is carried out by sandwiching a conductive anisotropic conductive adhesive film. A conventional thermocompression bonding apparatus (FIGS. 4 and 5) used for such thermocompression bonding will be described by way of an example in which a semiconductor chip is flip-chip bonded on a circuit board.

The apparatus shown in FIG. 4A holds a stage A for mounting a circuit board 43 to which a semiconductor chip 42 is temporarily bonded via an anisotropic conductive adhesive film 41, and an anisotropic conductive adhesive film 41. Semiconductor chip 42 and circuit board 4
3 and a pressure head B for heating and pressing. In this case, the stage A has a structure in which a stage plate 44 made of ceramic such as alumina having good dimensional stability against heat is held on a holding table 45. The pressure head B is composed of a stainless steel block 47 having a resistance heating type heater rod 46 built therein. As the stainless block 47, a relatively large stainless block is used in order to reduce the temperature change due to the increase and decrease in the number of thermocompression shots per unit time and to maintain the flatness of the surface.

[0004] The apparatus shown in FIG.
4 is a device in which a glass plate 48 is used and the tip of the pressure head B is a pulse heater 49.

In the apparatus shown in FIGS. 4A and 4B, since heating is performed only from the heater head B above the object to be heated and compressed, the number of thermal compression shots per unit time increases. Accordingly, there is a problem that the temperature of the stage A rises and the stage surface warps, and as a result, connection reliability decreases. When a circuit board 43 having relatively good thermal conductivity such as a ceramic board is used, the stage A is 200 ° C. or more lower than the temperature of the pressure head B.
The heat from the pressure head B diffuses through the circuit board 43,
As a result, sufficient thermocompression bonding cannot be performed, and there is a concern that connection reliability is reduced. For this reason, it is necessary to set the temperature of the pressure head B to be considerably higher than the curing temperature of the anisotropic conductive adhesive film and to set the thermocompression bonding time long, so that the thermocompression bonding cost cannot be avoided.

Heat supply to the anisotropic conductive adhesive film portion (fillet portion) 41a protruding from the periphery of the semiconductor chip 42 is performed only by radiation from the pressure head B and heat conduction from the semiconductor chip 42. There is a problem that the fillet portion 41a is not sufficiently cured and does not sufficiently adhere to the circuit board 43. In order to sufficiently cure this portion, it is conceivable to heat the semiconductor chip 42 at a higher temperature than before using the pressure head B. However, applying excessive heat shock to the semiconductor chip 42 is not sufficient. There is a concern that the reliability of this will decrease.

Therefore, recently, in order to reduce the temperature change of the stage A and the temperature difference between the stage A and the pressure head B by increasing or decreasing the number of thermocompression shots per unit time, FIG. As shown in the drawing, a resistance heating type heater rod 50 is also built in the holding table 45.

[0008]

[0005] However, as shown in FIG.
In the case where 0 is incorporated, in order to maintain the flatness of the stage plate 44 and ensure the safety during the thermocompression bonding operation, it is necessary to set the practical maximum heating temperature of the holding table 45 to about 60 ° C. was there. For this reason, even if the holding table 45 is heated as shown in FIG.
At present, the temperature difference between the stage plate 44 and the stage plate 44 exceeds 200 ° C., and as a result, a decrease in connection reliability cannot be avoided.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to maintain the flatness of the stage during thermocompression bonding and minimize the temperature difference between the stage and the pressure head. It is an object of the present invention to provide a thermocompression bonding device that can be thermocompression-bonded with reduced size and high connection reliability.

[0010]

The present inventor has found that the above-mentioned object can be achieved by forming the surface of the stage in contact with the object to be thermally press-bonded from a ceramic heater.
The present invention has been completed.

That is, the present invention relates to a thermocompression bonding apparatus for thermocompression bonding at least two thermocompression bonding objects to each other via an adhesive film, wherein a stage for mounting the thermocompression bonding object and a stage mounted on the stage. And a pressing head for pressurizing the object to be thermally compressed, wherein the surface of the stage in contact with the object to be thermally compressed is formed of a ceramic heater. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the thermocompression bonding apparatus of the present invention includes at least two thermocompression bonding objects, for example, a semiconductor chip 2 and a circuit through an adhesive film such as a thermosetting anisotropic conductive adhesive film 1. A thermocompression bonding apparatus for thermocompression-bonding a substrate 3 to each other, comprising a stage A for mounting a thermocompression bonding object (semiconductor chip 2 and circuit board 3) and a thermocompression bonding object mounted on the stage A. And a pressure head B for pressing. In the present invention, the surface of the stage A that comes into contact with the object to be thermally pressed is constituted by the ceramic heater 4.

Since the ceramic heater 4 generally has good dimensional stability against heat, it can heat its surface to a relatively high temperature while maintaining its surface flatness. Therefore, by forming the surface of the stage A from the ceramic heater 4, the stage A and the pressure head B
As a result, the anisotropic conductive adhesive film 1 including the anisotropic conductive adhesive film portion (fillet portion) 1a protruding around the semiconductor chip 2 can be sufficiently reduced. By thermosetting under pressure, thermocompression bonding with high connection reliability can be performed.

Further, since the ceramic heater 4 can be used also as a pulse heater, there is an advantage that the tact time is shortened.

Further, since the ceramic heater 4 has good temperature controllability, the surface temperature profile can be intentionally designed. Therefore, thermocompression bonding conditions can be selected according to the types of the semiconductor chip 2 and the circuit board 3 which are the objects to be thermocompression bonded, and the connection reliability can be improved.

As the ceramic heater 4, Kyocera Corporation,
A known ceramic heater such as Adamant Kogyo can be used.

In the embodiment shown in FIG.
Is held by the holding table 5, but the holding table 5 may be omitted, and the stage A may be constituted by the entire ceramic heater 4.

The pressure head B may be constituted by a stainless steel block 7 having a built-in resistance heating type heater rod 6 as in the prior art. However, as shown in FIG. The surface in contact with the chip 2 may be composed of a ceramic heater 8 having good dimensional stability against heat and good temperature controllability, and may be held by the holder 9. This eliminates the need to use a stainless block having a large heat capacity, so that the size of the pressure head B can be reduced, and the thermocompression bonding apparatus can be downsized. Further, the pressurized head B can perform pulse heating of the thermocompression-bonded object. Moreover, since the temperature profile of the surface can be intentionally designed, the stage A
And the temperature profile of the pressure head B can be matched with each other. As a result, better connection reliability can be realized.

Since the pressure head B can be heated from the stage A, it is not necessary to provide a heating means such as the heater rod 6.

In the thermocompression bonding apparatus of the present invention, it is desired that the thermocompression bonding can be performed so that the temperature difference between the stage A and the pressure head B is as small as possible. Usually, the temperature difference is set within 100 ° C., preferably within 50 ° C. In this case, it is preferable to provide a temperature adjusting device 10 as shown in FIG. As such a temperature control device 10, a known device can be used.
The temperatures of the stage A and the pressure head B are detected, respectively,
Any device can be used as long as it can turn on and off the heating by the ceramic heater 4 or the ceramic heater 8 based on the detection results.

Further, a temperature profile control device (for example, HEC-103, Inc.) for adjusting the temperature profile of the stage A and the pressure head B to substantially the same, by using such a temperature control device 10. Jiko).

The thermocompression bonding apparatus according to the present invention is capable of
The present invention is applied to the case where the above-mentioned thermocompression-bonded object is thermocompression-bonded, and can be preferably applied particularly when high-precision thermocompression bonding is required. For example, it can be preferably used when an electronic element such as a semiconductor chip or a liquid crystal panel is thermocompression-bonded to various substrates using an anisotropic conductive adhesive film.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below by experiments.

In the following experimental examples, 20 μm
6.3 m with Au bumps of 150 μm pitch arranged
m square semiconductor chip and 1.1 mm thick glass epoxy circuit board (A) (18 μm thick Cu pattern / Ni plating / Au plating; 150 μm pitch (line width 100 μm)
m, space width 50 μm), manufactured by Hitachi Chemical Co., Ltd.) or 1.1 mm thick alumina-based ceramic circuit board (B) (15 μm thick Au paste pattern; 150 μm
Pitch (line width 100 μm, space width 50 μm)
And a 50 μm thick anisotropic conductive adhesive film (FP
10425, manufactured by Sony Chemical Co., Ltd.), and thermocompression-bonded using the thermocompression bonding apparatus shown in FIG. 2 while changing the thermocompression bonding conditions.

For comparison, thermocompression bonding was performed using a thermocompression bonding apparatus shown in FIG.

Experimental Example 1 In this experimental example, the reaction rate of the thermosetting binder in the anisotropic conductive adhesive film and the PCT (pressure cooker test; 121 ° C./2.1 atm / 100% Rh) were used.
Was examined for the time required for the resistance to increase by 100 mΩ or more. This relationship serves as one index when selecting the thermocompression bonding conditions required to achieve the desired connection reliability.

That is, the circuit board (A) and the semiconductor chip were thermocompressed with the thermocompression bonding apparatus shown in FIG. 2 via the anisotropic conductive adhesive film. Here, the temperature of the stage-side ceramic heater was set to 180 ° C., the temperature of the pressure-head-side ceramic heater was set to 220 ° C., and the thermocompression bonding time was adjusted. The reaction rate of the thermosetting binder was adjusted.

FIG. 6 shows the obtained results. From these results, it can be seen that the higher the reaction rate, the longer the time required for the resistance increase (100 mΩ or more) of the anisotropic conductive adhesive film, and practically the reaction rate needs to be 90% or more. .

Experimental Example 2 In this experimental example, when the heating temperature on the stage side was set to 40 ° C. or 100 ° C., the relationship between the thermocompression bonding time and the heating temperature of the anisotropic conductive adhesive film was examined. By examining this relationship, it can be estimated whether it is possible to shorten the thermocompression bonding time or to lower the heating temperature of the ceramic heater on the pressure head side.

That is, using the thermocompression bonding apparatus shown in FIG.
The circuit board (A) and the semiconductor chip were thermocompression bonded via an anisotropic conductive adhesive film under the conditions of a stage temperature of 40 ° C., a pressure head temperature of 230 ° C., and a thermocompression bonding time of 20 seconds. The obtained result is shown by a solid line in FIG.

Further, using the thermocompression bonding apparatus shown in FIG. 2, a stage ceramic heater temperature of 100.degree.
The circuit board (A) and the semiconductor chip were thermocompression bonded via an anisotropic conductive adhesive film under the conditions of 10 ° C. and a thermocompression bonding time of 20 seconds. The obtained result is shown by a dotted line in FIG.

As shown in FIG. 7, when the temperature on the stage side is increased, the anisotropic conductive adhesive film is quickly heated to a predetermined temperature (about 1 ° C.).
80 ° C.). This indicates that the heating time can be shortened by increasing the temperature on the stage side. Actually, in the case of the apparatus shown in FIG. 4A, the reaction rate of the thermosetting binder in the anisotropic conductive adhesive film in which the thermocompression bonding time is 20 seconds is 92%, and that in the case of 15 seconds is 85%.
On the other hand, in the case of the apparatus shown in FIG.
The reaction rate of the thermosetting binder in the anisotropic conductive adhesive film at 0 seconds was 96%, and at 15 seconds was 92%.
Therefore, the thermocompression bonding time can be reduced by at least 5 seconds in the case of the apparatus shown in FIG.

Further, from this experimental example, it is understood that if the temperature on the stage side is increased, the temperature on the pressure head side can be set lower (in the case of the apparatus shown in FIG.
Set to 30 ° C., set to 210 ° C. for the apparatus of FIG. 2).

Experimental Example 3 In this experimental example, the relationship between the temperature of the ceramic heater of the stage and the temperature difference between the upper and lower surfaces of the circuit board was examined.
The temperature difference between the upper and lower surfaces of the circuit board is one index for selecting thermocompression bonding conditions.

That is, using the thermocompression bonding apparatus shown in FIG. 2, the temperature of the pressure head is set so that the temperature of the anisotropic conductive adhesive film becomes 180 ° C. after 20 seconds, and the thermocompression time is 20 seconds. Then, the circuit board (A), the circuit board (B), and the semiconductor chip were each thermocompression-bonded via an anisotropic conductive adhesive film. The results obtained are shown in FIG.

FIG. 8 shows that the higher the temperature of the ceramic heater of the stage, the smaller the temperature difference between the upper and lower surfaces of the circuit board.

Experimental Example 4 In this experimental example, the temperature difference between the upper and lower surfaces of the circuit board and the PC
T (pressure cooker test; 121 ° C / 2.1a)
(tm / 100% Rh) and the time required for a resistance increase of 100 mΩ or more was examined. This relationship serves as one index when selecting the thermocompression bonding conditions required to achieve the desired connection reliability.

That is, the results of Experimental Example 3 for the circuit board (A) were made to correspond to the results of PCT of the thermocompression-bonded article manufactured in Experimental Example 3, and the results are shown in FIG.

FIG. 9 shows that the smaller the temperature difference between the upper and lower surfaces of the circuit board, the higher the connection reliability. Practically, it is desired that the temperature difference be within 100 ° C, preferably within 50 ° C.

Experimental Example 5 In this experimental example, the periphery of the semiconductor chip (1.5 mm
The relationship between the reaction rate of the thermosetting binder in the anisotropic conductive adhesive film portion (fillet portion) protruding outside and the temperature of the ceramic heater of the stage was examined. It can be expected that the higher the reaction rate of the fillet portion, the higher the connection reliability.

That is, using the thermocompression bonding apparatus shown in FIG. 2, the temperature of the ceramic heater of the pressure head was set to 210 ° C., and the circuit board (A) and the semiconductor chip were bonded under the thermocompression bonding time of 10 seconds. Thermocompression bonding was performed via an anisotropic conductive adhesive film. The results obtained are shown in FIG.

FIG. 10 shows that the higher the stage-side temperature, the higher the fillet reaction rate. Actually, PCT (pressure cooker test; 121 ° C./2.1 atm /
At 100% Rh), the time required for a resistance increase of 100 mΩ or more was about 100 hours, but it was 168 hours at a conversion of 60% and 192 hours at a conversion of 80%.

Experimental Example 6 In this experimental example, PCT (pressure cooker test; 121 ° C.) when the temperature profiles of the stage side and the pressure head side were substantially the same.
/2.1atm/100%Rh) (1
(At least 00 mΩ).

That is, the circuit board (A) and the semiconductor chip were thermocompression-bonded via the anisotropic conductive adhesive film by the thermocompression bonding apparatus shown in FIG. Here, the temperature profiles of the stage side and the pressure head side were set as shown in FIG. As a result, the result of PCT of the selected thermocompression bonding product was 240 hours or more, and thermocompression bonding with extremely high connection reliability was achieved.

[0046]

According to the thermocompression bonding apparatus of the present invention, the flatness of the stage during thermocompression can be maintained, and the temperature difference between the stage and the pressure head can be minimized. Therefore, thermocompression bonding with high connection reliability is possible. In addition, it is possible to shorten the thermocompression bonding time and to lower the thermocompression bonding temperature of the pressure head.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a thermocompression bonding apparatus according to the present invention.

FIG. 2 is an explanatory view of the thermocompression bonding apparatus of the present invention.

FIG. 3 is an explanatory view of a thermocompression bonding apparatus of the present invention.

FIG. 4 is an explanatory view of a conventional thermocompression bonding apparatus (FIG. 4 (a),
(B)).

FIG. 5 is an explanatory view of a conventional thermocompression bonding apparatus.

FIG. 6 is a graph showing the relationship between the reaction rate of a thermosetting binder in an anisotropic conductive adhesive film during thermocompression bonding and the time required for a resistance increase of 100 mΩ or more in a PCT (pressure cooker test).

FIG. 7 is a relationship diagram between a thermocompression bonding time and a heating temperature of an anisotropic conductive adhesive film.

FIG. 8 is a diagram showing the relationship between the temperature of the ceramic heater of the stage and the temperature difference between the upper and lower surfaces of the circuit board.

FIG. 9 is a graph showing the relationship between the temperature difference between the upper and lower surfaces of a circuit board and the time required for a resistance rise of 100 mΩ or more in a PCT (pressure cooker test).

FIG. 10 shows a reaction rate of a thermosetting binder in an anisotropic conductive adhesive film portion protruding around a semiconductor chip;
It is a relation diagram with the temperature of the ceramic heater of a stage.

FIG. 11 is a temperature profile on the stage side and the pressure head side.

[Explanation of symbols]

1 anisotropic conductive adhesive film, 2 semiconductor chip,
3 circuit board, 4,8 ceramic heater, 5 holder, 6 heater rod, 7 stainless block, 9 holder, 10 temperature controller

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junji Shinozaki 12-3 Satsuki-cho, Kanuma-shi, Tochigi Sony Chemical Co., Ltd.

Claims (6)

[Claims] 1. A thermocompression bonding apparatus for thermocompression-bonding at least two thermocompression bonding objects to each other via an adhesive film, comprising: a stage for mounting the thermocompression bonding object; and a thermocompression bonding device mounted on the stage. What is claimed is: 1. A thermocompression bonding apparatus having a pressure head for pressing an object, wherein a surface of a stage in contact with the object to be thermocompression-bonded is formed of a ceramic heater. 2. The thermocompression bonding apparatus according to claim 1, wherein the adhesive film is an anisotropic conductive adhesive film. 3. The pressurizing head in contact with the object to be thermally press-bonded is made of a ceramic heater.
The thermocompression bonding apparatus as described in the above. 4. The thermocompression bonding apparatus according to claim 1, wherein the ceramic heater is a pulse heater. 5. The thermocompression bonding device according to claim 1, further comprising a temperature adjustment device for controlling a temperature difference between the stage and the pressure head to be within 50 ° C. during thermocompression bonding. apparatus. 6. The apparatus according to claim 1, further comprising a temperature profile control device for making the temperature profiles of the stage and the pressure head substantially the same during thermocompression bonding.
5. The thermocompression bonding apparatus according to any one of 4.