JPH03190198A - Bonding head of outer lead and method of bonding - Google Patents

Abstract

PURPOSE:To increase a thermocompression bonder in temperature to enable it to meet the temperature characteristics of solder and an outer lead to bond the outer lead by thermocompression by a method wherein cold air is made to blow against the thermocompression bonder, the bonder of comparatively low temperature is made to press an outer lead against the electrode of a board, and cold air is stopped to blow. CONSTITUTION:A heat transfer part 6 is made to come into contact with a thermocompression bonder 7, the bonder 7 is made to rise quickly in temperature, an electrode is fully fused by heating, an outer lead L is pressed against an electrode by the pushing force of a rod 25 of a cylinder 24, and the lead L is bonded to the electrode by thermocompression. The heat transfer part 6 is made to ascend to be distant from the thermocompression bonder 7 and stops transferring heat to the bonder 7, cold air is made to blow off from the lower end of an upright tube 2 through which a nozzle shaft is made to penetrate to cool down the thermocompression bonder 7 and the electrode to a temperature of 180 deg.C or below, and the bonder 7 is kept to press the outer lead against the electrode. When there is no fear that the outer lead leaps up, the bonder 7 is made to ascend to stop pressing the outer lead, the cold air is made to stop blowing off, the electrode is gradually cooled down and cured, and the outer lead L can surely be bonded to the electrode.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an outer lead bonding head and a bonding method, and more specifically, to a bonding head and a bonding method for outer leads, and more specifically, a bonding head for bonding outer leads of a semiconductor chip manufactured by the TAB method to a substrate by thermocompression. Concerning means.

(Prior Art) Manufacturing a semiconductor chip by mounting a semiconductor on a film carrier made of a synthetic resin film and punching out the film carrier is known as the TAB method.

The semiconductor chip manufactured in this manner has outer leads formed by punching out the film carrier as described above, and it is not possible to bond the outer leads to the electrode portions formed on the substrate. , generally called outer lead bonding.

(Problem to be Solved by the Invention) To adhere the outer lead to the substrate, the outer lead is landed on the electrode part formed on the top surface of the substrate, and a thermocompression bonder is pressed onto the outer lead to heat and melt the electrode part. This is done by

However, the solder that is the material for the electrode part has a temperature characteristic of melting and hardening, and although there are differences depending on the type of solder, in general, it is heated gradually to 160 to 180 degrees Celsius and then heated to 220 degrees Celsius.
It is desirable to melt the material by heating it all at once to a temperature above .degree. C. and then gradually cool it to harden it. Further, since the outer lead is extremely thin and made of synthetic resin such as polyimide, it is not preferable to heat it suddenly to a high temperature because the quality of the material changes, so it is preferable to heat it gradually.

Therefore, an object of the present invention is to provide a bonding means that can satisfy such temperature characteristics of solder and outer leads.

(Means for Solving the Problems) For this purpose, the present invention provides a nozzle shaft that can be raised and lowered and has a suction portion for a semiconductor chip at its lower end, and a nozzle shaft that is placed on the side of this suction portion and is mounted on a substrate by this suction portion. The bonding head for the outer lead is composed of a thermocompression bonder for thermocompression bonding the outer lead to the substrate, and a cooling means for blowing cold air onto the thermocompression bonder.

(Function) According to the above configuration, by blowing cold air, the outer lead is first pressed against the electrode part of the board by the thermocompression bonder having a relatively low temperature, and then by interrupting the blowing of cold air, the temperature of the thermocompression bonder is increased. , and thermocompression bond the outer lead to the electrode part.

(Example) Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of the bonding head, and FIG. 2 is a partially cutaway perspective view. 1 is a plate-shaped support frame, and a standpipe 2 is attached to the center thereof. A nozzle shaft 3 is fitted into the standpipe 2 so as to be movable up and down, and a suction section 4 for a semiconductor chip P is provided at the lower end thereof. This semiconductor chip P is manufactured by the TAB method, and as shown in FIG. It is extending. Note that there are some semiconductor chips in which outer leads L extend in two directions from two sides of the semiconductor C, and the means according to the present invention can be applied to such semiconductor chips as well.

Reference numeral 5 denotes a heat block as a heating means provided on the lower surface of the support frame l, and the standpipe 2 passes through this heat block 5. In FIG. 2, 12 is a power supply line. A tapered heat transfer portion 6 is integrally provided on the lower surface of the heat block 5 and projects downward. Reference numeral 7 denotes a thermocompression bonder provided on the side of the suction part 4, and is configured to press the suction part 4 into contact with the outer lead L extending in four directions.
It has a rectangular frame shape that surrounds the body, and its cross-sectional shape has an enlarged portion 7a and a small pressing portion 7b. As will be described in detail later, this pressing portion 7b is pressed against the outer lead L and is thermocompression bonded to an electrode portion made of solder formed on a substrate, and the enlarged portion 7a serves as a heat storage portion. This thermocompression bonder 7 may be formed integrally with the heat block 5, but in this embodiment, by making the thermocompression bonder 7 separate from the heat block 5, it is possible to change the type of semiconductor chip. This can be done by replacing only the thermocompression bonder 7. In this case, if the outer leads L extend in two directions, the thermocompression bonder does not need to be formed into a rectangular frame shape, but has a shape corresponding to the outer leads L in the two directions.

In FIG. 2, reference numeral 8 denotes a frame-shaped bracket arranged to surround the heat block 5, and the thermocompression bonder 7 is connected to this bracket 8 via a shaft 9. 10 is a coil spring that urges the thermocompression bonder 7 downward; 11;
is a bearing portion that guides the shaft 9 to move up and down.

In FIG. 2 and FIG. 4(a), reference numeral 14 denotes a contacting and separating means for moving the thermocompression bonder 7 up and down to bring it into contact with and away from the heat transfer part 6, and is attached to the mounting plate 22 on the lower surface of the support frame l. , pin 1
It has an arm 15 which is rotatably attached to the arm 6. A roller 17 that comes into contact with the lower surface of the bracket 8 is pivotally attached to the tip of the arm 15 . Reference numeral 18 denotes a spring member that urges the roller 17 downward, that is, in a direction that separates the thermocompression bonder 7 from the heat transfer section 6 downward. Reference numeral 19 denotes a rod that is vertically installed on the frame 21 (see FIG. 1), and its lower end is connected to a roller 20 that is pivoted to the other end of the arm 15.
The roller 17 is pressed against the lower surface of the bracket 8 against the spring force of the spring material 18. As will be detailed later, by bringing the thermocompression bonder 7 into contact with and separating from the heat transfer part 6,
The heat transfer from the heat transfer part 6 to the thermocompression bonder 7 is disconnected, and the thermocompression bonder 7
temperature control. In addition, in the bonded state where the thermocompression bonder 7 is in the raised position, a small distance t is ensured between the two 6 and 7 (see the partially enlarged view of FIG. 4(a)), and thus it is possible to ensure the distance t. This prevents the thermocompression bonder 7 from being excessively heated by the heat transfer section 6.

In FIG. 4(,a), a shaft 23 is erected on the side of the upper surface of the support frame l. 24 is the shaft 23
It is a multistage cylinder installed above the rod 2.
5 is in contact with the upper surface of the shaft 23. 26 is a second cylinder, and its rod 27 is connected to the upper surface of the support frame l. This second cylinder 26 supports the load of the support frame 1, the heat block 5, etc. by its retreating force F2 (see FIG. 3(C)).

This cylinder 24 is a pressurizing means for strongly pressing the presser 7 against the outer lead, and also serves as an elevating means for raising and lowering the thermocompression bonder 7 independently from the suction section 4.

In FIG. 4(a), reference numeral 40 denotes a pulse motor for raising and lowering the nozzle shaft 3, which rotates a threaded rod 41 to raise and lower a nut body 42 screwed thereon. A block 43 is attached to the upper end of the nozzle shaft 3, and a coil spring 44 urges the nozzle shaft 3 downward. 45, the upper end of which is the NAND body 42
A roller 46 that presses against the lower surface of the block 43 is attached to the lower end of the shaft. 47 is a lifting guide block for the shaft 45, and 48 is a coil spring that urges the shaft 45 upward. In each figure, the biasing direction of the spring is indicated by an arrow.

Therefore, when the pulse motor 40 is operated and the NAND body 42 is lowered, the shaft 45 is lowered against the spring force of the coil spring 48, the roller 46 is also lowered, and the nozzle shaft 3 is lowered by the spring force of the coil spring 44. do. Further, when the NAND body 42 rises, the shaft 45 is moved by the coil spring 48.
The nozzle shaft 3 is raised by the spring horn of the roller 4.
It is pushed up by 6 and rises.

In FIG. 1, 50 is a motor for rotating the nozzle shaft 3 around its axis, 51 is a cam, 52 is a cam follower, 53 is a rotor to which the cam follower 52 is attached, and 54 is a rotor 53 A vertical shaft 55 is a roller attached to the tip of a rod 56 extending from the nozzle shaft 3 side and pressed against the shaft 54. These means horizontally rotate the semiconductor chip P attracted to the attraction part 4 and correct its orientation and position in the θ direction, but since they are not directly related to the present invention, a detailed explanation thereof will be omitted. Omitted.

FIG. 3 shows a cooling means, in which 13 is an inner tube inserted between the nozzle shaft 3 and the upright tube 2;
Cold air is sent between the standpipe 2 and the inner pipe 13 through the pipe 28, and this cold air is blown out from the lower end of the standpipe 2 toward the pressing part 7b of the thermocompression bonder 7 that presses the outer lead L. (see dashed arrow). The pipe 28 is connected to the upper part of the standpipe 2, and the blown cold air descends between the standpipe 2 and the inner pipe 13. Therefore, the nozzle shaft 3 is cooled over its entire length to prevent the nozzle shaft 3 from being excessively heated by the heat block 5 and thermally deformed, thereby preventing errors in bonding accuracy.

The temperature of this cold air is, for example, room temperature.

There is also a gap between the nozzle shaft 3 and the inner tube 13,
This gap serves as a thermal insulator to prevent heat from the heat block 5 from being transmitted to the nozzle shaft 3. Furthermore, as mentioned above,
If cold air is blown out from the lower end of the standpipe 2 into which the nozzle shaft 3 is inserted, the cold air will be blown out in all directions, and the cold air can be evenly blown against the pressing part 7b located so as to surround the suction part 4. However, the cold air blowing means may be provided separately from the standpipe 2 and the heat block 5, and the cold air may be blown from diagonally above the thermocompression bonder 7 toward the pressing portion 7b of the presser 7. However, the specific configuration of the cooling means is not limited to this embodiment.

This bonding head consists of the above structure,
Next, the bonding method will be explained with reference to FIGS. 4(a) to 4(f).

The bonding head that has sucked the semiconductor chip P on the lower end of the suction part 4 arrives above the substrate S (see FIG. 4(a)).
). Next, by driving the motor 40, the suction part 4
descends, mounts the semiconductor chip P on the substrate S, and lands the outer leads L on the electrode portions 30 made of solder formed on the upper surface of the substrate S (FIG. 4(b)).

Next, the support frame 1 is lowered by actuating the cylinder 24. Then, the roller 20 is separated from the rod 19, the arm 15 is rotated by the spring force of the spring member 18, the thermocompression bonder 7 is lowered, and its pressing portion 7b is pressed against the outer lead L.
and press it against the electrode part 30 (see figure (C)
)).

In this case, if the pressing part 7b is suddenly pressed against the outer lead with a strong force, the outer lead shield electrode part 30 is likely to be adversely affected. Therefore, this means provides a multi-stage cylinder 2
By first protruding the rod 25 of No. 4 with a weak force and lowering the thermocompression bonder 7, and rotating the arm 15 by the spring force of the spring material 18, the pressing part 7b is first pressed against the outer lead L with a weak force. (Figure 4(C)).

Next, when the heat transfer part 6 lands on the thermocompression bonder 7, the pressing part 7b is strongly pressed against the outer lead by increasing the protruding force Fl of the rod 25 of the multistage cylinder 24 ((d) in the same figure). .

Next, by moving the rod 25 of the cylinder 24 upward, the heat block 5 is raised (FIG. 3(e)).
). In this state, the thermocompression bonder 7 is separated from the heat transfer part 6,
The spring force of the spring material 18 maintains the pressed state of the outer lead L. Next, as the rod 27 further rises, the thermocompression bonder 7 separates from the outer lead L, and the bonding work is completed (FIG. 1(f)'').

Incidentally, the solder that is the material of the electrode section 30 has temperature characteristics of melting and hardening. That is, generally 160' to 1
After heating to about 80° C., it is desirable to melt the material by heating it all at once to 220° C. or higher, and then gradually cool it and harden it. Therefore, this device controls the heating temperature of the electrode section 30 in the following manner.

The temperature of the heat block 5 is always constant at 220 to 230°C, but in FIGS. 4(a) and 4(b), the temperature of the thermocompression bonder 7 is approximately 1
It is preheated to about 60-180°C. Next, the same figure (C
), the thermocompression bonder 7 descends and lands on the outer lead, and presses the outer lead L while pressing the electrode part 3.
0 gradually.

Next, as shown in FIG.
The temperature of the thermocompression bonder 7 is immediately raised to about 220 to 230°C to completely melt the electrode part 30, and in this state, the outer lead L is The outer lead L is thermocompression bonded to the electrode part 30 by strongly pressing it against the electrode part 30.

Next, as shown in FIG. 6(e), the heat transfer part 6 rises and separates from the thermocompression bonder 7, interrupting the heat transfer to the thermocompression bonder 7, and blowing out cold air as shown by the broken line arrow. As a result, the thermocompression bonder 7 and the electrode portion 30 are cooled down to 180° C. or lower, and the pressing state by the thermocompression bonder 7 is continued. Note that the electrode part 3
0 to 220°C or higher, the thermocompression bonder 7 is attached to the heat transfer part 6
When the pressed state of the outer lead L is released by suddenly raising the outer lead L, the electrode part 30 is heated and is in a molten state, so the outer lead jumps up and is easily separated from the molten electrode part 30. Therefore, as described above, even after raising the heat transfer part 6, the pressing state of the outer lead L by the thermocompression bonder 7 is continued, and the electrode part 30 is
After cooling to about 0° C. and eliminating the risk of the outer lead springing up, the thermocompression bonder 7 is raised to release the pressed state. Then, as shown in FIG.
When the pressing state is released, the blowing of cold air is stopped, and the electrode part 30 is gradually cooled and hardened, and the outer lead is fixed to the electrode part 30.

In this way, the present means allows the thermocompression bonder 7 to be moved into and out of contact with the heat block 5, which is a heating means, and also has a means for cooling the pressing part 7b and the electrode part 30 by blowing out cold air. The electrode part 30 can be heated and melted well, and the outer lead L can be reliably bonded to the electrode part 30. Note that the above temperatures such as 180° C. and 220° C. are exemplary, and these temperatures vary depending on the type of solder.

(Effects of the Invention) As explained above, according to the present invention, the temperature of the thermocompression bonder is controlled by the cooling means, the thermocompression bonder at a relatively low temperature is first pressed against the outer lead, and then the temperature of the thermocompression bonder is Since the outer lead and the electrode part can be heated to high temperature by raising the temperature, the outer lead will not change in quality. It can be thermally bonded well.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a perspective view of a bonding head, Fig. 2 is a partially cutaway perspective view, Fig. 3 is a sectional view of a cooling means, and Fig. 4 is a working order. FIG. 3... Nozzle shaft 4... Adsorption part 7... Thermocompression bonder 30... Electrode part P... Semiconductor chip L... Outer lead S... Substrate

Claims (2)

[Claims] (1) A nozzle shaft that can be raised and lowered to have a suction part for a semiconductor chip at its lower end, and a thermocompression bonding device located on the side of this suction part to thermocompress the outer lead mounted on a board to this board by means of this suction part. What is claimed is: 1. An outer lead bonding head comprising: a thermocompression bonding element; and a cooling means for blowing cold air onto the thermocompression bonding element. (2) The nozzle shaft is lowered, and the semiconductor chip adsorbed by the suction part at the lower end of the nozzle shaft is mounted on the substrate, and the thermocompression bonder is lowered to blow cold air onto the thermocompression bonder. The thermocompression bonder is pressed against the outer leads of the semiconductor chip, the temperature of the thermocompression bonder is increased by interrupting the blowing of cold air, and after this pressing state is continued, the thermocompression bonder is raised. A method for bonding an outer lead, characterized in that the outer lead is thermocompression bonded to an electrode portion formed on a substrate by releasing the pressed state.