JPH05259352A - Bonding head of outer lead and bonding method - Google Patents

Abstract

PURPOSE:To bond outer leads to electrode parts by sensing the temperature of a thermocompression bonding element located at a standby position by a thermosensor and by bringing a heating part and the thermocompression bonding element in contact on the basis of its result. CONSTITUTION:When a heating part 6 and a thermocompression element 7 are at a standby position, a rod 19 is protruded and retracted while the temperature of the thermocompression bonding element 7 is sensed by a thermosensor 62 to keep the thermocompression bonding element 7 within a predetermined temperature range. Next, the rod 25 of a multistage cylinder 24 is projected with a low force to make the thermocompression bonding element 7 descend, and an arm 15 is rotated by the force of a spring member 18 to press the pressure part 7b onto an outer lead L. Upon the grounding of the heating part 6 on the thermocompression bonding element 7, the pressure part 7b is pressed strongly on the outer lead L by increasing the projecting force of the rod 25 of the multistage cylinder 24. The thermocompression bonding element 7 is heated strongly to melt down an electrode part 30 rapidly. Then, the rod 25 is retracted upward to blow out cooling air and cool it. The temperature of the thermocompression bonding element 7 is sensed by the thermosensor 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer lead bonding head and a bonding method.
When the outer lead of the semiconductor chip manufactured by the TAB method is thermocompression bonded to the electrode part of the substrate by the thermocompression bonding element, the heating element is contacted with and separated from the thermocompression bonding element to control the temperature of the thermocompression bonding element. The present invention relates to a bonding head and a bonding method.

[0002]

2. Description of the Related Art A semiconductor is mounted on a film carrier made of a synthetic resin film, and a semiconductor chip is manufactured by punching the film carrier.
It is known as the AB method.

The semiconductor chip thus manufactured has an ultrathin outer lead formed by punching the film carrier as described above, and the outer lead is used as an electrode formed on the substrate. Bonding to a part is generally called outer lead bonding.

The present applicant has previously proposed an outer lead bonding means (Japanese Patent Laid-Open No. 3-190199). This is a thermocompression-bonding element 7 for pressing the outer lead against the electrode portion of the substrate and performing thermocompression bonding (reference numeral is used in the publication),
The heat transfer part 6 is pressed against the thermocompressor 7, and the heat block 5 as a heating means for heating the heat transfer part 6 and the like. Particularly, as shown in FIGS. 4 (a) to 4 (f). Then, the outer lead L is pressed against the electrode portion 30 of the substrate S by the thermocompressor 7, and the outer lead L is attached to the electrode portion 30 while heat and pressure are applied to the thermocompressor 7 by the heat transfer portion 6.
It is designed to be thermocompression bonded to.

In this conventional means, as shown in FIG. 4 (d), the heat transfer portion 6 is pressed against the thermocompression bonding element 7 so that the thermocompression bonding element 7 is soldered to the electrode portion 30 of the substrate S. After the solder is melted by heating it to a melting temperature (generally about 183 ° C.) or higher, the heat transfer portion 6 as shown in FIG.
To separate from the thermocompression-bonding member 7 and cool the thermocompression-bonding member 7 to a temperature not higher than the melting temperature of the solder by cold air to solidify the solder, and then heat the heat transfer unit 6 and the heat transfer unit 6 as shown in FIG. Raise the crimping member 7 to the standby position, and at this standby position, the heat transfer section 6
Thus, the thermocompression bonding element 7 is preheated to prepare for the next thermocompression bonding.

[0006]

Although the desirable preheating temperature of the thermocompression-bonding member 7 at the standby position is equal to or higher than the melting temperature of the solder (for example, 250 ° C.), the temperature of the thermocompression-bonding member 7 is controlled by the conventional means. Since the current temperature of the thermocompression-bonding member 7 is unknown, therefore, before the thermocompression-bonding member 7 is heated to a predetermined temperature (for example, 250 ° C. as described above),
As shown in FIG. 4C, the thermocompression-bonding member 7 is easily lowered to press the outer lead L against the electrode portion 30, and in this case, the solder is not melted and a bonding defect of the outer lead L is likely to occur. there were.

Further, as shown in FIG. 4D, whether the thermocompression-bonding member 7 holds the solder melting temperature of 183 ° C. or higher while the thermocompression-bonding member 7 is pressed against the outer lead L. It was also unclear whether or not the thermocompression-bonding element 7 was cooled to 183 ° C. or lower by cold air in the state shown in FIG. Incidentally, if the thermocompression-bonding element 7 rises as shown in FIG. 6F before the molten solder solidifies, the outer leads L jump up and separate from the molten solder. As described above, the conventional means has a problem that various bonding defects are likely to occur because the temperature of the thermocompression bonding element 7 is not controlled.

[0008] Therefore, an object of the present invention is to provide a bonding means capable of surely adhering an outer lead manufactured by the TAB method to a substrate.

[0009]

To this end, the present invention detects the temperature of the thermocompression bonding element for thermocompression bonding the outer lead of the semiconductor chip mounted on the substrate to the electrode portion of this substrate, and the temperature of this thermocompression bonding element. A temperature sensor, a heating unit for heating the thermocompressor, and a contacting / separating means for contacting / separating the thermocompressor with the heating unit to keep the thermocompressor in the standby position at a predetermined temperature are provided. is there.

[0010]

In the above structure, the semiconductor chip adsorbed by the adsorbing portion is mounted on the substrate, the preheated thermocompressor is pressed against the outer leads of the semiconductor chip, and the pressed state is released. The lead is bonded to the electrode part of the substrate. In this case, the temperature of the thermocompressor at the standby position is detected by the temperature sensor, and based on the detection result, the heating unit and the thermocompressor are brought into contact with and separated from each other so that the thermocompressor maintains the desired temperature. To do.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view of a bonding head, and FIG. 2 is a partially cutaway perspective view. Reference numeral 1 is a plate-shaped support frame, and an upright tube 2 is attached to the central portion thereof. A nozzle shaft 3 is vertically inserted into the upright tube 2, and a suction portion 4 for the semiconductor chip P is provided at the lower end portion thereof. The semiconductor chip P is manufactured by the TAB method, and the ultra-fine and ultra-thin outer leads L formed by punching out the film carrier extend from four sides of the semiconductor C in four directions. In addition, from the two sides of the semiconductor C to 2
The outer lead L extends in some directions, and the means according to the present invention can be applied to such a semiconductor chip.

Reference numeral 5 denotes a heat block as a heating means provided on the lower surface of the support frame 1, and the upright tube 2 penetrates the heat block 5. In FIG. 2, reference numeral 12 is a power supply line.

On the lower surface of the heat block 5, a tapered heating portion 6 (corresponding to the heat transfer portion of the above-mentioned conventional means) 6 is integrally projected downward. Reference numeral 7 denotes a thermocompressor provided on the side of the adsorption portion 4, which has a rectangular frame shape surrounding the adsorption portion 4 so that it can be pressed against the outer leads L extending in four directions, and its cross-sectional shape is It has an enlarged portion 7a and a thin tongue-shaped pressing portion 7b. As will be described later in detail, the pressing portion 7b is pressed against the outer lead L and thermocompression-bonded to the electrode portion made of solder formed on the substrate. The enlarged portion 7a is for eliminating the temperature unevenness of the pressing portion 7b. It is a heat storage part.

In FIG. 2, reference numeral 8 is a frame-shaped bracket arranged so as to surround the heat block 5, and the thermocompression-bonding element 7 is connected to this bracket 8 via a shaft 9. Reference numeral 10 is a coil spring for urging the thermocompressor 7 downward, and 11 is a bearing ring portion for guiding the shaft 9 up and down.

2 and 3, the arm 15 is attached to the mounting plate 22 mounted on the lower surface of the support frame 1 by the pin 1
It is rotatably mounted around 6 as a center. A roller 17 that supports the bracket 8 from below is pivotally attached to the tip of the arm 15.

In FIG. 3, 19 is a cylinder, and its rod 19a is grounded to a roller 20 axially attached to the outer end of the arm 15. As shown by the solid line in FIG. 3, when the rod 19a is projected and is in contact with the roller 20, the arm 15 is prevented from rotating downward by the spring force of the spring member 18, and the bracket 17 of the roller 17 does not descend. I support this from below. In this state, the thermocompression-bonding member 7 at the upper standby position is brought into contact with or abuts the heating unit 6 with a small interval t1 and is heated by the heating unit 6.
Further, as shown by the chain line in FIG. 3, when the rod 19a is pulled upward, the arm 15 slightly rotates downward due to the spring force of the spring member 18, and accordingly, the bracket 8 and the thermocompression-bonding member 7 coupled thereto. Also slightly descends, the gap between the thermocompression-bonding member 7 and the heating unit 6 increases (see the partially enlarged view t2), and the strong heating of the thermocompression-bonding member 7 by the heating unit 6 is interrupted.

Temperature sensors 61 and 62 such as thermocouples are internally provided in the heating section 6 and the thermocompression bonding element 7. In this embodiment, the heat block 5 and the heating unit 6 are always 450 ° C.
The thermocompression-bonding element 7 in the standby position shown in FIG. 3 is heated to a certain degree, and is controlled with 250 ° C. as the upper limit temperature and 240 ° C. as the lower limit temperature. Therefore, in the proximity state shown by the solid line in FIG. 3, when the temperature of the thermocompression-bonding member 7 reaches 250 ° C., the rod 19a of the cylinder 17 projects and the thermocompression-bonding member 7 is separated from the heating portion 6 by a distance t2 as shown by the chain line in FIG. Then, the heating of the thermocompressor 7 by the heating unit 6 is stopped. Further, when the temperature of the thermocompression-bonding member 7 drops to 240 ° C. in that state, the rod 19a of the cylinder 19 is projected to bring the thermocompression-bonding member 7 close to the heating unit 6 as shown by the solid line in the figure (interval t1). The thermocompressor 7 is heated again to 250 ° C. That is, the arm 15 and the cylinder 19 and the like constitute the contacting / separating means 14 that moves the thermocompressor 7 up and down relative to the heating unit 6 to bring it into contact with and separate it from the heating unit 6 to switch between heating and stopping heating of the thermocompressor 7. ..
The control of the cylinder 19 and the like is performed by a computer. As such contacting / separating means, besides the cylinder 19, for example, a cam means driven by a motor or the like can be applied. This bonding head is provided with a cool air blowing means similar to that shown in FIG. 3 of JP-A-3-190199, but the description thereof will be omitted.

In FIG. 3, a shaft 23 is provided upright on the upper surface side of the support frame 1. 24 is shaft 2
3 is a multi-stage cylinder, and its rod 25 is grounded to the upper surface of the shaft 23. 26 is the second
Cylinder of which the rod 27 is a support frame 1
Is bonded to the upper surface of. This second cylinder 26
The withdrawal force F2 (see FIG. 5) supports the load of the support frame 1, the heat block 5, and the like. The cylinder 24 is a pressurizing means for strongly pressing the thermocompressor 7 against the outer lead L, and also serves as an elevating means for elevating the thermocompressor 7 independently of the suction portion 4.

In FIG. 3, reference numeral 40 denotes a pulse motor for moving the nozzle shaft 3 up and down, which is a ball screw 4
1 is rotated and the nut body 42 screwed to this is raised and lowered. 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. Reference numeral 45 denotes a shaft whose upper end is pressed by the nut body 42, and a roller 46 which is pressed against the lower surface of the block 43 is attached to the lower end of the shaft. Reference numeral 47 is a lifting guide block for the shaft 45, and 48 is a coil spring for urging the shaft 45 upward. In each drawing, the urging direction of the spring is indicated by an arrow.

Therefore, when the pulse motor 40 is operated and the nut body 42 descends, the shaft 45 moves to the coil spring 4
8, the roller 46 also descends, and the nozzle shaft 3 descends by the spring force of the coil spring 44. When the nut body 42 rises, the shaft 45 rises due to the spring force of the coil spring 48, and the nozzle shaft 3
Is pushed up by the roller 46 and rises.

In FIG. 1, 50 is a motor for rotating the nozzle shaft 3 about its axis, 51 is a cam, 52 is a cam follower, 53 is a rotator to which the cam follower 52 is attached, and 54 is a rotation. A shaft extending vertically from the child 53, and a rod 56 extending from the nozzle shaft 3 side.
Is a roller that is attached to the tip of the roller and presses against the shaft 54. These means horizontally rotate the semiconductor chip P sucked by the suction unit 4 to change its direction and correct the position in the θ direction.

This bonding head has the above-mentioned structure. Next, the bonding method will be described with reference to FIGS.

The bonding head which has sucked the semiconductor chip P on the lower end of the suction portion 4 arrives above the substrate S by driving a moving means (not shown) (FIG. 3). Here, when the heating unit 6 and the thermocompression-bonding member 7 are in the raised standby position, the rod 19a of the cylinder 19 is projected and retracted while the temperature of the thermocompression-bonding member 7 is detected by the temperature sensor 62 as described above. Set the thermocompressor 7 in a predetermined temperature range (240
C. to 250.degree. C.).

When the motor 40 is driven, the suction portion 4 is lowered to mount the semiconductor chip P on the substrate S,
The outer lead L is landed on the electrode portion 30 made of solder formed on the upper surface of the substrate S (FIG. 4).

Then, the cylinder 24 is actuated to lower the support frame 1. Then, the roller 20 separates from the rod 19, the arm 15 rotates by the spring force of the spring member 18, the thermocompression-bonding member 7 descends, and the pressing portion 7b presses the outer lead L, and this is applied to the electrode portion 30. Press (Fig. 5). In this case, if the pressing portion 7b is suddenly pressed against the outer lead L with a strong force, the outer lead L
The electrode portion 30 is likely to be adversely affected. So this means
The rod 25 of the multi-stage cylinder 24 is first projected with a weak force to lower the thermocompressor 7, and the arm 15 is rotated by the spring force of the spring material 18, whereby the pressing portion 7b is moved with a weak force first to the outer lead L. Press on. Then heating section 6
After the landing on the thermocompressor 7, the thrust force F1 of the rod 25 of the multistage cylinder 24 is increased to strongly press the pressing portion 7b against the outer lead L (FIG. 6). By thus pressing the high-temperature heating unit 6 against the thermocompression-bonding member 7, the thermocompression-bonding member 7 is strongly heated and the electrode unit 30 is quickly melted.

Then, the rod 25 of the cylinder 24 is retracted upward to slightly raise the heating unit 6 (FIG. 7). In this state, the thermocompression-bonding element 7 is separated from the heating section 6, and the spring force of the spring material 10 keeps the outer lead L pressed. Further, in this state, cold air is blown toward the thermocompression-bonding element 7 (see the broken line arrow) to rapidly cool the thermocompression-bonding element 7 to a temperature below the melting temperature of solder (generally about 183 ° C.), preferably about 180 ° C. Of course, the temperature of the thermocompression-bonding element 7 is detected by the temperature sensor 62.

Then, when the rod 27 is further raised, the thermocompression-bonding member 7 is separated from the outer lead L and the bonding work is completed, and the thermocompression-bonding member 7 returns to the standby position shown in FIG. 3 again (FIG. 8). In this case, the temperature of the thermocompression-bonding member 7 is detected by the sensor 62, and when it is confirmed that the temperature of the thermocompression-bonding member 7 becomes equal to or lower than the melting temperature of the solder, the thermocompression-bonding member 7 rises and the outer lead Since the pressed state of L is released, the outer lead L does not jump up due to unsolidified solder, and the outer lead L is connected to the electrode portion 3
Can be firmly fixed to 0. The above-mentioned 183 ° C, 240
The above temperatures such as ° C, 250 ° C, and 450 ° C are mere examples, and these temperatures differ depending on the type of solder and the like.

[0028]

As described above, according to the present invention, the outer lead can be reliably bonded to the electrode portion of the substrate while controlling the temperature of the thermocompression bonding element. In particular, by detecting the temperature of the thermocompressor with the temperature sensor and by bringing the thermocompressor and the heat transfer part into contact with each other at the standby position, the thermocompressor can be maintained at a predetermined temperature, and the outer lead can be fixed by the thermocompressor. Since the pressed state can be released by confirming that the temperature of the thermocompression bonding element has become lower than the melting temperature of the solder while being pressed against the electrode part of the substrate, the outer lead can be reliably bonded to the electrode part. In addition, the thermocompressor is not excessively heated or cooled for a long time, and when the thermocompression bonding reaches a predetermined temperature, the descending operation and the ascending operation can be performed quickly, so that workability is improved. Can perform bonding work at high speed.

[Brief description of drawings]

FIG. 1 is a perspective view of a bonding head according to the present invention.

FIG. 2 is a partially cutaway perspective view according to the present invention.

FIG. 3 is a front view of a work order according to the present invention.

FIG. 4 is a front view of a work order according to the present invention.

FIG. 5 is a front view of a work order according to the present invention.

FIG. 6 is a front view of a work order according to the present invention.

FIG. 7 is a front view of a work order according to the present invention.

FIG. 8 is a front view of a work order according to the present invention.

[Explanation of symbols]

 4 Adsorption part 5 Heating means 6 Heating part 7 Thermocompressor 14 Contact / separation means 30 Electrode part 62 Temperature sensor P Semiconductor chip L Outerlead S Substrate

Claims (2)

[Claims] 1. A thermocompression bonding element for adsorbing a semiconductor chip, a thermocompression bonding element for thermocompression bonding an outer lead of the semiconductor chip, which is adsorbed by the adsorption portion and mounted on a substrate, to an electrode portion of the substrate, and the thermocompression bonding element. Sensor for detecting the temperature of the thermocompressor, a heating section for heating the thermocompressor, and a contacting / separating means for contacting and separating the thermocompressor and the heating section so as to keep the thermocompressor at the standby position at a predetermined temperature. An outer lead bonding head characterized by having and. 2. A semiconductor chip attracted to the suction part is mounted on a substrate by lowering the suction part, and then a thermocompression contactor is lowered to connect the outer leads of the semiconductor chip to the electrode part of the substrate by the thermocompression contactor. In addition to pressing, the heating section heated by the heating means heats the thermocompressor to heat-weld the outer lead to the electrode section, and then the heating section and the thermocompressor are lifted to release the pressed state. Thus, in the outer lead bonding method in which the outer lead is adhered to the substrate, the temperature of the thermocompressor at the standby position is detected by a temperature sensor,
An outer lead bonding method characterized in that the thermocompression bonding element is driven to contact and separate the heating unit and the thermocompression bonding element so as to maintain a predetermined temperature range.