JP3246111B2 - Thermocompression bonding equipment and thermocompression bonding 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 thermocompression bonding apparatus and a thermocompression bonding method for connecting an inner lead and an outer lead in a semiconductor device, and an object of the invention is to make a number of crimping points uniform.

[0002]

2. Description of the Related Art In general, a thermocompression bonding apparatus used for connection of leads in a semiconductor device includes a crimping body (eg, a package substrate) mounted on a crimping stage, and a crimping body (eg, a lead) mounted on the crimping body. In this configuration, the crimping body is pressed against the crimped body by a crimping tool having a heating unit (heater).

In such an apparatus, a stage supported by a gimbal mechanism is swingable so as to follow a pressing surface of a pressing tool. FIG. 8 is a structural view (a) of the main part of a conventional thermocompression bonding apparatus and operation explanatory diagrams of the stage (b) and (c). FIG. 9 is a method of fixing a body to be crimped in the conventional thermocompression bonding apparatus. FIG.

In a thermocompression bonding apparatus 4 for connecting an inner lead of a lead 2 to a semiconductor chip 1 and connecting an outer lead (compression-bonded body) of the lead 2 to a package substrate (compression-bonded body) 3, a crimping stage 5 includes a base. A steel ball 7 disposed at the center of the base 6 and a leaf spring 8 having one end fixed to the base 6 and the other end fixed to the stage 5 are held.

[0005] The base 6 is supported by a plurality of guide posts 10 which are fitted to the guide bush 9 and which can move up and down. The drive shaft 12 which is fitted to the cylinder 11 and which can move up and down has an appropriate pressing force f. The base 6 is pushed up via the load cell 13.

[0006] The substrate 3 is fixed to the stage 5, the semiconductor chip 1 is mounted on the substrate 3, and the outer leads of the leads 2 whose inner leads are connected to the semiconductor chip 1 via bumps 14 are connected to the outer leads. Terminal of stacked substrate 3
15 is pressed by the pressing of the heat pressing tool 16.

The pressing force F at the time of crimping of the crimping tool 16 for connecting the outer lead and the terminal 15 is the pressing force f of the drive shaft 12.
The pressing force f is detected by the load cell 13 and controlled.

In this thermocompression bonding apparatus, the position of the stage 5 is supported by the balance of the leaf spring 8. For example, the pressing surface of the tool 16 or the upper surface of the stage 5 is inclined as shown by a dashed line in FIG. Stage 5
The upper surface follows the pressing surface of the tool 16. That is, the stage 5 inclined as shown in FIG. 8 (b) rotates following the tool 16 as shown in FIG.
, The center of the stage 5 is shifted by the dimension δ.

In FIG. 9, in order to mount and fix the package substrate 3 on the stage 5, the substrate 3 on which a large number of pins having low mechanical strength hangs is mounted on a ceramic carrier 17, and
The stage 5 has an exhaust hole 18 for adsorbing the lower surface of the carrier 15.
Is provided, and the carrier 17 is vacuum-adsorbed to the stage 5.

The conventional carrier 17 hangs down from the substrate 3 and accommodates a number of pins (not shown) so that the pins do not protrude out of the carrier 17.

[0011]

SUMMARY OF THE INVENTION In a thermocompression bonding apparatus,
In order to improve the quality of thermocompression bonding (bonding), it is necessary to prevent damage to the crimped body, accurately control the crimping load and crimping temperature, and monitor the eutectic state (joining state) of the joint alloy. .

However, in the conventional apparatus, when the pressing surface of the pressing tool 16 or the upper surface of the stage 5 is inclined, the upper surface of the stage 5 rotates following the pressing surface of the tool 16, and the center of rotation is a steel ball. 7, and the upper surface of the stage 5 is located above the center of the steel ball 7.

Therefore, as shown in FIG. 8 (a), the distance between the center of the steel ball 7 and the upper surface of the stage 5 is d, the inclination angle of the stage 5 is θ, and the tool 16 as shown in FIG. Assuming that the pressing surface width is a, when the lead 2 and the terminal 15 are crimped, a slip of (a × cos θ) −a occurs between the lead 2 and the pressing surface of the tool 16, and the slip causes the lead 2 However, there has been a problem that the sheet is easily damaged or a displacement of the pressure bonding is easily caused.

Further, the package substrate 3 is mounted on the stage 5.
And a suction pipe for vacuum-sucking the ceramic carrier 17 are connected, and these become disturbance factors of the supporting state of the stage 5 using the leaf spring 8.

The stage 5 also depends on the disturbance factor.
This makes it difficult to reproduce the posture accurately, which results in a recognition error and an initial contact error of the crimped part.
There is also a problem that the displacement of the lead 2 with respect to 15 occurs.

In a thermocompression bonding apparatus in which the stage 5 is pushed up by the pressing force f and the tool 16 is pressed by the pressing force F, the pressing force between the lead 2 and the terminal 15 becomes f. No.

Therefore, a pressing force f is set for the cylinder 11 utilizing the air pressure in the conventional device 4 using a relatively good linear characteristic such as a bellofram cylinder, and the pressing force is monitored by the load cell 13. It is a configuration to do. But,
In such a configuration, there is no particular problem when the crimping area is relatively large, but it is difficult to accurately control the crimping force with micro bonding having a small crimping area.

Further, in the conventional method of fixing the package substrate 3 via the ceramic carrier 17, the undulation of the lower surface of the substrate 3 affects the thermocompression bonding of the leads 2, and the ceramic carrier 17 has a thermal stress of several μm during the compression. Deform to the extent,
High-precision crimping is impaired.

[0019]

A first means of the present invention is as follows.
A first pair of rotatable shafts 22 facing in the X-axis direction, a second pair of rotatable shafts 23 facing in the Y-axis direction, and a first or second pair of rotatable shafts 22 or 23; Thermocompression bonding stage 21 supported on one side, a first or second pair of rotatable shafts
A swinging plate 27 supported on the other of the swinging plates 22 and 23; and a supporting member 29 mounted on the swinging plate 27 and supporting the pair of rotatable shafts 22 or 23, and a center axis is positioned in the same horizontal plane. The rotatable shafts 22 and 23 are disposed such that the crimped surfaces of the crimped body 3 mounted on the upper surface of the stage 21 are rotatable shafts 22 and 23.
This device is configured so as to be substantially aligned with a horizontal plane including the axis.

The second means of the present invention is that a thermocompression bonding stage 31 on which a body 3 to be crimped is mounted and which moves down by the pressing of a crimping tool 16 is swingable in the X-axis direction and the Y-axis direction.
This is a device provided with a stopper 32 for holding the stage 31 before moving down by the tool 16 substantially horizontally.

A third means of the present invention is an apparatus provided with both the features of the first means and the features of the second means. The fourth means of the present invention is that the crimping drive source of the crimping tool 16 for pressing the crimping body 2 against the crimped body 3 includes a coarse movement source 36 for driving the tool 16 toward the stage, and a coarse movement source 36. And a fine movement source 38 for driving the tool 16 in the same direction as the above, and the coarse movement source 36 drives the tool 16 up to a predetermined pressure appropriately weaker than the pressing force for pressing with the pressure required for crimping. This is a pressure bonding method driven by a fine movement source 38 capable of increasing the pressure finer than the movement source 36.

According to a fifth aspect of the present invention, the pins 30 penetrate a ceramic carrier 61 which is a medium for fixing the package substrate 3 on which the plurality of pins 30 connected to the semiconductor chip 1 hang down to the thermocompression bonding stage 21. Stage 21 with through holes
The ceramic carrier 61 is provided with an intake hole 62 for adsorbing the ceramic carrier 61 and a metal plate 63 with which the tip of the pin 30 penetrating the ceramic carrier 61 abuts. Fit into the through hole and pin
This is a crimping method in which the tip of 30 is brought into contact with the metal plate 63.

A sixth means of the present invention is a thermocompression bonding method employing both the fourth method and the fifth method. further,
A seventh means of the present invention is an apparatus having both the third means and the fifth means.

[0024]

According to the first means, when the stage swings and the pressed surface of the pressed object and the pressed surface of the tool follow each other, almost no slippage occurs between the tool and the pressed member. Therefore, damage to the crimped body caused by the conventional device is prevented.

According to the second means, the stopper regulates the influence of the wiring and the like communicating with the stage. for that reason,
The recognition error and the initial contact error of the crimping portion are reduced, the displacement of the crimping position is eliminated, and the reliability and reliability are improved.

According to the third means, the crimped body is prevented from being damaged, and the reliability and reliability of the crimping are improved. According to the fourth means, the pressing force by the tool is stabilized, and the reliability and reliability of the pressure bonding are improved.

According to the fifth means, it is possible to eliminate the influence of the undulation on the lower surface of the package substrate and the deformation of the ceramic carrier when the leads are pressed against the package substrate, and the uniformity in microbonding is improved.

According to the sixth means, both the effect of the fourth means and the effect of the fifth means are simultaneously achieved. Further, according to the seventh aspect of the present invention, the crimped body is prevented from being damaged, the reliability and reliability of the crimping are improved, and the lower surface of the package substrate is pressed when the leads are crimped to the package substrate. It is possible to eliminate the influence of the undulation and the deformation of the ceramic carrier, thereby improving the uniformity in micro bonding.

[0029]

FIG. 1 is an explanatory diagram of a main part configuration in an apparatus according to an embodiment of the present invention. FIG. 2 is a model diagram of the main part configuration shown in FIG.
FIG. 3 is an explanatory view of a main part configuration in a device according to another embodiment of the present invention, FIG. 4 is a model diagram for explaining a crimping force control method in a device according to still another embodiment of the present invention, and FIG. FIG. 6 is a perspective view showing an example of the configuration of the model shown in FIG. 4, and FIG. 7 is an explanatory view of an example of the configuration of a ceramic carrier for fixing a package substrate according to the present invention.

In FIG. 1, a stage 21 corresponding to the conventional stage 5 has a pair of shafts 22 for swinging the stage 21 in the front-rear direction (Y direction) and the stage 21 for swinging in the left-right direction. It is supported by a base 24 corresponding to the conventional base 6 via a pair of shafts 23 and the like.

A pair of support brackets 25 fixed to the base 24 and opposed in the front-rear direction rotatably support the shaft 23, and a bracket 26 is fixed to the tip of the shaft 23, and the pair of support brackets 26 swing. Moving plate 27
Stick to

At the left and right ends of the swinging plate 27, support brackets 28 are erected, and a support bracket 29 is fixedly attached to the tips of a pair of rotatable shafts 22 fitted to the respective support brackets 28. The stage 21 is fixed to the pair of support fittings 29.

The center axes of the shafts 22 and 23 are located in the same horizontal plane, and the upper surface 21a of the stage 21 is lower than that plane by the thickness of the object to be pressed (for example, the package substrate 3) as shown in FIG. I do.

Therefore, the stage 21 is moved by the axes 22 and 23 to
It is swingable in the front-rear direction (Y direction) and the left-right direction (X direction), and the swing center of the stage 21 is located on the surface of the body to be pressed fixed to the stage 21.

Therefore, the crimping apparatus using the stage 21 supported by the base 24 instead of the conventional stage 5 supported by the base 6 prevents the crimping tool 16 from rubbing the lead 2 and the crimping tool 16 There is no risk of damaging the lead 2.

In FIG. 3, the stage 31 supported on the base 6 by the steel ball 7 and the leaf spring 8 as in the conventional case is provided with a projecting portion outside the conventional stage 5, and when the drive shaft 12 pushes the stage 31 up. A stopper 32 that makes the upper surface of the stage 31 substantially horizontal comes into contact with the overhang portion.

The stage 31 mounts the package substrate 3 and the semiconductor chip 1, and when the tool 16 is pressed to connect the outer of the lead 2 having the inner connected to the semiconductor chip 1 to the terminal 15 of the substrate 3, Stage 5 of
Similarly, the steel ball 7 rotates about the center of the steel ball 7 as the rotation center.

However, the stage 31 regulated by the stopper 32 is substantially horizontal in that state, and is not affected by wiring or the like that impairs the appearance of the stage 31, so that the scratches caused by the tool 16 rubbing the lead 2 occur. Not to be.

Referring to FIG. 4, in the present embodiment relating to the active control of the crimping load, the tool 16 is roughly moved up and down by a motor 35 and a coarse movement pressing means (coarse movement source) 36, and is further moved by a fine movement pressing means (fine movement). The pressure-sensitive element 39 detects the pressing force of the crimping tool 16 for performing fine vertical movement by the source) 38 and pressing the lead 2 against the terminal 15.

The coarse motion pressing means 36 and the pressure sensing element 39 are intermediate members.
The tool 16 is connected in the vertical direction via 37, and the tool 16 is
It is connected to a pressure-sensitive element 39 via 38. As shown in FIG. 5, the pressurizing mechanism determines the position of the coarse pressurizing means 36 with respect to the crimping body (lead 2). Positioning of means 38, confirmation that tool 16 has contacted the crimping body, tool 16
Then, the fine motion pressing means 38 is driven to press the tool 16 against the crimping body, and the pressing force is detected.

In FIG. 6, which is a specific configuration example of the pressurizing mechanism described with reference to FIG. 4, a coarse motion pressurizing means 36 containing a motor 35 is a plate-like member 41 on which the motor 35 is mounted, Pulley 43 that transmits rotational power to a pair of ball screws 42
And a plate-like member 45 that moves up and down by the rotation of the belt 44 and the ball screw 42, and a plurality of shafts 46 that guide the member 45 to move up and down.

The fine motion pressing means 38 includes a stack type piezo element 47 having an upper surface adhered to a pressure sensitive element (load cell) 39 and a lower surface adhered to a tool joining member 49, and a member 49 formed by the piezo element 47.
It consists of multiple shafts 48 etc. that guide the fine vertical movement of
The crimping tool 16 hangs down from the member 49.

The crimping tool 16 accommodated a heater and a thermocouple, and the member 49 was made of an amber material to eliminate thermal expansion accompanying the heating of the tool 16. The cord 50 is connected to the thermocouple via a connector 51, and the cord 52 is connected to the heater via a connector 53.As an example of alignment of the tool 16, a laser beam 55 emitted from a laser source 54
Is irradiated onto the crimped portion of the lead 2 and the coordinates of the irradiated image are observed with a microscope (or visually). Then, when the irradiation image coordinates are at a predetermined value, the tool 16 is positioned above the irradiation image coordinates.

The thermocompression bonding method described with reference to FIGS. 4, 5, and 6 is applied to the regeneration of a partial bonding failure between the lead 2 and the terminal 15, and is extremely efficient and convenient. In FIG. 7, a ceramic carrier on which a substrate 3 is mounted on a stage 21 is shown.
61 is provided with a through hole through which a number of pins 30 hanging from the substrate 3 penetrate. When the carrier 61 is fixed to the stage 21 by a vacuum suction method using an intake hole 62 provided in the stage 21, the tip of the pin 30 Is a metal plate arranged on the upper surface of the stage 21
Contact 63.

Therefore, the inner leads are connected to the semiconductor chip 1.
Crimping tool for connecting lead 2 and substrate 3 connected to
When the outer leads of the leads 2 are pressed toward the substrate 3 using the 16, the pressing force F + f is dispersed and many pins 30 receive.

Accordingly, the substrate 3 is supported without directly contacting the carrier 61. This is due to the deformation (undulation) of the lower surface of the substrate 3 when the leads 2 are crimped, and
Conventional effects due to deformation due to thermal expansion of the carrier 61 can be eliminated.

Using the carrier 61, the tip of the pin 30 is a metal plate
In the crimping that comes into contact with the 63, a large number of pins 30 inevitably vary in length. Therefore, when the pressing force F + f is applied, the long pin 30 absorbs the excessive length by elastic deformation.

In FIG. 7, reference numeral 64 denotes a suction nozzle, and the nozzle 64 communicating with the suction hole 62 faces the center of the lower surface of the substrate 3. Therefore, the carrier 61 is fixed to the stage 21 by exhausting from the intake hole 62, and the substrate 3 is fixed to the stage 21 by the suction force from the nozzle 64.

Another embodiment of the present invention will be described with reference to FIGS. 1 and 3. In the other embodiment, the swing of the stage 21 in FIG. 1 is regulated by a stopper 32 in FIG. With this configuration, tool slippage is eliminated by the stage 21 and a large inclination of the stage 21 is prevented, so that the effect of the certainty and reliability of the pressure bonding is further improved.

Further, both the method of controlling the tool pressing force described with reference to FIG. 6 and the method of fixing the package substrate described with reference to FIG. 7 are employed in the same apparatus, and the description with reference to FIG. By adopting both the method using the stopper 32 and the method for fixing the package substrate described with reference to FIG. 7 to the same device, the reliability and reliability of the pressure bonding for mounting the semiconductor chip on the package substrate are improved. It will be further improved.

[0051]

As described above, according to the present invention, the crimped body is not damaged, the recognition error and the initial contact error of the crimped portion are reduced, the pressing force by the crimping tool is stabilized, and the undulation of the lower surface of the package substrate is achieved. In addition, the influence of deformation of the ceramic carrier is eliminated, and the reliability, uniformity, and reliability of pressure bonding are improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a main part configuration in an apparatus according to an embodiment of the present invention.

FIG. 2 is a model diagram of a main part configuration shown in FIG. 1;

FIG. 3 is an explanatory diagram of a main part configuration in an apparatus according to another embodiment of the present invention.

FIG. 4 is a model diagram for explaining a crimping force control method in the apparatus according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of the operation of the model shown in FIG. 4;

FIG. 6 is a perspective view showing a configuration example of the model shown in FIG. 4;

FIG. 7 is an explanatory diagram of a configuration example of a ceramic carrier according to the present invention.

FIG. 8 is an explanatory view of the operation of a main part and a stage of a conventional thermocompression bonding apparatus.

FIG. 9 is an explanatory view of a method of fixing a body to be compressed in a conventional thermocompression bonding apparatus.

[Explanation of symbols]

 1 is a semiconductor chip 2 is a lead (crimped body) 3 is a package substrate (crimped body) 16 is a crimping tool 21, 31 is a crimping stage 22 is a first rotatable shaft 23 is a second rotatable shaft 27 is a rocking plate 29 is a support for supporting the first rotatable shaft 30 is a pin hanging down from the package substrate of the semiconductor device 32 is a stopper for regulating the state of the stage 36 is a coarse pressurizing source (coarse moving source) 38 is a fine motion pressurizing source (fine motion source) 61 is a ceramic carrier 62 is an intake hole 63 is a metal plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21 / 60,21 / 52,21 / 58 B23Q 1 / 25,7 / 00 F16M 11/12

Claims (7)

(57) [Claims] 1. A first pair of rotatable shafts facing in the X-axis direction, and a second pair of rotatable shafts facing in the Y-axis direction.
(23) A thermocompression bonding stage (21) supported on one of the first or second pair of rotatable shafts, supported on the other of the first or second pair of rotatable shafts. A swinging plate (27), a support mounted on the swinging plate and supporting the one pair of rotatable shafts;
(29), and the first and second pair of rotatable shafts are disposed so that the center axis is located in the same horizontal plane, and the crimped body (3) mounted on the upper surface of the stage is provided. A thermocompression bonding apparatus, wherein a pressure bonding surface is substantially aligned with a horizontal plane including a center axis of the rotatable shaft. 2. A crimping tool (16) on which a crimped body (3) is mounted.
A stage (31) for thermocompression bonding, which descends by the pressing of the tool, is swingable in the X-axis direction and the Y-axis direction, and a stopper (32) which makes the stage almost horizontal before the downward movement by the tool.
The thermocompression bonding device is provided. 3. The first pair of rotatable shafts according to claim 1,
And a second pair of rotatable shafts (23), a stage (21), a rocking plate (27), a support (29) and a stopper (32) according to claim 2.
A thermocompression bonding apparatus, characterized in that the stopper is disposed so that the stage before moving down by the crimping tool (16) is substantially horizontal. 4. A crimping drive source of a crimping tool (16) for pressing a crimping body (2) against a crimped body (3) mounted on a stage (21) drives the crimping tool toward the stage. Coarse motion source (3
6), and a fine movement source (38) for driving the tool in the same direction as the coarse movement source, and the coarse movement source is pressed to a predetermined pressure that is appropriately weaker than the pressing force required for the pressure required for the crimping. A thermocompression bonding method comprising: driving the tool; and driving the tool by the fine movement source capable of increasing the pressure more than the predetermined pressure than the coarse movement source. 5. Many pins connected to a semiconductor chip (1)
Stage for thermocompression bonding of package substrate (3) on which (30) hangs
A ceramic carrier (61) as a medium to be fixed to (21) is provided with a through hole through which the large number of pins penetrate, and the stage has an intake hole (62) for adsorbing the ceramic carrier and a ceramic carrier (61). A metal plate (63) with which the tips of the pins abut is provided, and when the ceramic carrier is suction-fixed to the stage, an intermediate portion of the pins fits into the through-hole, and A thermocompression bonding method, wherein the tip is brought into contact with the metal plate. 6. The thermocompression bonding stage (21) is provided with an air inlet (62) and a metal plate (63) according to claim 5, and uses a ceramic carrier (61) according to claim 5 to form a semiconductor chip (61). A package substrate (3), on which a number of pins (30) connected to (1) are suspended, is mounted on the stage, and the crimping body (2) is crimped on the package substrate using the crimping drive source according to claim 4. And a thermocompression bonding method. 7. A thermocompression bonding apparatus according to claim 3, wherein the package substrate (3) on which a number of pins (30) connected to the semiconductor chip (1) hangs is fixed to a thermocompression bonding stage (21). A certain ceramic carrier (61) is provided with a through hole through which the large number of pins penetrate, and the stage is provided with an intake hole (62) for adsorbing the ceramic carrier and the tips of the large number of pins penetrating through the ceramic carrier. A metal plate (63) that is in contact with the metal carrier, and when the ceramic carrier is suction-fixed to the stage, an intermediate portion of the plurality of pins is fitted into the through-hole and the tips of the plurality of pins are in contact with the metal plate. A thermocompression bonding apparatus characterized in that: