JPH0982764A - Thermocompression bonding method for chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for the thermocompression bonding a chip which makes it possible to improve the yield of production by suitably managing the elongation of a film carrier upon thermocompression bonding. SOLUTION: The outer leads 4 laminated on the film carrier 2 of a chip 1 are temporarily attached to the electrode 8 of a display panel 5 by a temporary attachment tool 9. The deviations of the points A1, A2 of the carrier 2 and the points B1, B2 of the panel 5 are respectively detected by first camera 22 and second camera 23. If the deviations fall within an allowable value, the carrier 2 is primarily press-bonded to the panel 5. Similarly, the deviations of the points A1, A2 of the carrier 2 and the points B1, B2 of the panel 5 are detected. In this case, the length between the points B1 and B2 of the panel 5 is set as a true value, and the degree of the elongation of the carrier 2 upon thermocompression bonding is verified. If the verified result is wrong, the press- bonding conditions are altered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip thermocompression bonding method for bonding an outer lead of a chip made of a film carrier to an electrode of a substrate such as a display panel.

[0002]

2. Description of the Related Art A display panel used as a display for electronic equipment is assembled by laminating two transparent plates, and electrodes formed at a narrow pitch on the edges of the display panel have drivers for driving the display panel. As many chips are mounted as. As this chip, a chip manufactured by bonding a bare chip to a film carrier is often used. The film carrier is made of polyimide resin or the like, and a large number of outer leads are provided at a narrow pitch on the surface thereof. The chip is mounted by aligning the outer leads with the electrodes of the display panel and pressing a high temperature tool against the film carrier to thermocompress the outer leads to the electrodes.

By the way, the outer leads provided on the film carrier are likely to be misaligned due to manufacturing errors and thermal expansion of the film carrier during thermocompression bonding. On the other hand, since the electrodes of the display panel and the outer leads of the chip are formed with an extremely fine and narrow pitch, high alignment accuracy is required. Therefore, conventionally, in consideration of such a point, the outer leads are thermocompression bonded as follows.

FIG. 8 is an explanatory view of a conventional thermocompression bonding method for outer leads of a chip. 8A and 8B are plan views, and FIG. 8A is before thermocompression bonding and FIG. 8B is after thermocompression bonding. In the figure, 1 is a chip, which is a film carrier 2
It is made by bonding the bare chip 3 to the surface of the. Further, a large number of outer leads 4 are attached to the surface of the film carrier 2 with copper wires or the like at a narrow pitch. Further, a large number of extremely fine electrodes 8 are formed at a narrow pitch on the edge of the transparent plate 6 that constitutes the display panel.
A first mark A1 (hereinafter referred to as A1 point) for position detection and a second mark A2 are provided at both ends of the film carrier 2.
(Hereinafter, referred to as A2 point) are provided at intervals. Similarly, a first mark B1 (hereinafter referred to as B1 point) and a second mark B2 (hereinafter referred to as B2 point) are also provided at the edge of the transparent plate 6 with a space. A
1 point, A2 point, B1 point and B2 point are marks for aligning the outer lead 4 and the electrode 8.

In FIG. 8A, the positional accuracy of points B1 and B2 of the transparent plate 6 and the distance accuracy of the distance LG between them are extremely high. This is because the glass plate, which is the material of the transparent plate 6, has extremely good dimensional accuracy and is not easily deformed after molding. Therefore, the reliability of the position and the distance LG is extremely high. On the other hand, the film carrier 2
Accuracy of A1 point and A2 point and distance LT1 between them
The distance accuracy of is a little low. This is mainly due to the vulnerability of the material of the film carrier 2. Further, as described above, when a high temperature tool is pressed against the film carrier 2, the film carrier 2 is thermally expanded and the distance LT1 becomes slightly longer. Therefore, as shown in FIG. 8A, the distance LT1
Are set to be slightly shorter than the distance LG (that is, in consideration of thermal expansion of the film carrier 2), the positions of the points A1 and A2 are set.

Next, the thermocompression bonding method will be described. First, FIG.
As shown in (a), A1 point, A
Observing two points, B1 point and B2 point, lateral shifts Δd1 and Δd2 between A1 point and B1 point and A2 point and B2 point are obtained. In the present invention, the lateral direction is the direction in which the outer leads 4 and the electrodes 8 are arranged. As is apparent from FIG. 8A, before thermocompression bonding, LT1 = LG− (Δd1 +
Δd2). Since the reliability of the distance LG is extremely high as described above, the distance LG can be regarded as a true value.
The distance LG may be a design value (catalog value) or an actual measurement value measured by a measuring means such as a camera.

Next, as shown in FIG. 8B, the outer leads 4 are aligned with the electrodes 8, and the film carrier 2
Press a tool (not shown) onto the outer lead 4
Is thermocompression bonded to the electrode 8. At this time, the deviation Δd between the points A1 and B1 and the points A2 and B2 is Δd = (Δd1 + Δd
2) ÷ 2 (that is, the total deviation amount (Δd1 + Δ
The outer lead 4 and the electrode 8 are aligned with each other by evenly distributing d2) in the lateral direction. As described above, the outer lead 4 is thermocompression bonded to the electrode 8, and the chip 1 is mounted on the transparent plate 6 of the display panel.

[0008]

However, the above-mentioned conventional method has the following problems. That is, the positional accuracy of points B1 and B2 on the transparent plate 6 side is high, but the positional accuracy of points A1 and A2 on the film carrier 2 side is low, and the thermocompression bonding temperature, thermocompression bonding load, thermocompression bonding time, film carrier The film carrier 2 is not necessarily thermally expanded by the amount of the theoretical value due to the thermocompression bonding due to variations in the material and the like. Therefore, as shown in FIG. 8B, after thermocompression bonding, the points A1 and B1 and the points A2 and B2 are likely to have large deviations Δdl ′ and Δd2 ′ that are equal to or larger than the allowable values. As described above, the products having the deviations Δdl and Δd2 exceeding the allowable values are defective products and must be excluded from the line. Therefore, the conventional thermocompression bonding method has a problem of low production yield.

Therefore, an object of the present invention is to provide a method for thermocompression bonding of a chip, which can appropriately improve the production yield by appropriately controlling the elongation of the film carrier associated with thermocompression bonding.

[0010]

To this end, the present invention provides a method of observing a mark of a first mark and a mark of a second mark of a film carrier with a camera after thermocompression bonding to obtain a distance between the two marks. The thermocompression bonding conditions were changed based on the obtained distance size.

Further, the substrate is a display panel made of a transparent plate, and the distance is obtained with the positions of the first mark and the second mark provided on the edge of the display panel as true positions. did.

Further, the temperature of the tool, the crimping load, the crimping time,
At least one of the descending speed or the cooling control is included.

Before the thermocompression bonding of the film carrier to the substrate, a step of optically measuring the distance between the first mark and the second mark provided at a distance on the film carrier, and the film carrier is heated on the substrate. After bonding the outer leads provided on the film carrier by pressure bonding to the electrodes provided on the substrate, the first mark and the second mark are formed.
The step of optically measuring the distance of the mark, the step of calculating the ratio of the two measured distances to obtain the elongation rate of the film carrier, and the step of feeding back this elongation rate to the film carrier design process. Configured.

[0014]

According to the above construction, the outer leads and the electrodes can be correctly aligned and thermocompression bonded while accurately grasping the thermal expansion of the film carrier. When the alignment accuracy is higher than the allowable value, thermocompression bonding is stopped, only the chip is excluded from the line, and the substrate such as the display panel is reused, whereby the yield can be greatly improved.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. 1 is an overall perspective view of a chip mounting apparatus according to an embodiment of the present invention, FIG. 2 is a partial perspective view of a temporary crimping machine of the chip mounting apparatus, and FIG. 3 is a partial plan view of the chip and a display panel. 4 is a perspective view of the main crimping machine of the chip mounting apparatus, FIG. 5 is a partial plan view of the chip and the display panel, FIG. 6 is a flowchart of the operation of the thermocompression bonding method of the chip mounting apparatus, and FIG. It is a setting table figure of pressure bonding conditions. The same elements as those in the conventional example shown in FIG. 8 are designated by the same reference numerals.

In FIG. 1, the chip mounting apparatus 10 is
Loader 11, ACF sticking machine 12, chip temporary crimping machine 1
3, a chip main press bonding machine 14, a positional deviation inspection machine 15, and an unloader 16 are arranged side by side. These devices are connected to the computer 17 by a cable 18, and the computer 17 performs line management.

Display panels are stocked in the loader 11, and the display panels are sent to the ACF sticking machine 12 one by one. The ACF sticking machine 12 puts A on the electrode of the display panel.
CF (anisotropic conductive tape) is attached. The ACF is a bonding tape for thermocompression bonding the outer leads of the chip to the electrodes of the display panel. Chip temporary crimping machine 1
3 temporarily attaches the outer leads of the chip on the electrodes of the display panel. The chip main press-bonding machine 14 performs main thermocompression bonding of the chip outer leads temporarily attached by the temporary press-bonding machine 13 to the electrodes of the display panel. The displacement inspection machine 15 inspects whether the outer leads of the chips are correctly thermocompression bonded to the electrodes of the display panel without a large displacement. The unloader 16 collects and stocks the display panel to which the chip is bonded.

An apparatus and method for temporarily attaching the outer leads of the chip to the electrodes of the display panel will be described below with reference to FIGS. Reference numeral 5 is a display panel in which transparent plates 6 and 7 are bonded together. The display panel 5 is sent out from the loader 11 shown in FIG. 1, and the ACF sticking machine 12 sticks the ACF on the electrode 8 formed on the edge portion of the upper surface of the lower transparent plate 6, and then the temporary press bonding machine 13 Sent to. 2 and 3
In the temporary press machine 13, the chip 1 is attached to the electrode 8 of the transparent plate 6.
The outer lead 4 is temporarily attached. In each figure, the ACF attached on the electrode 8 is omitted because the figure becomes complicated.

In FIG. 2, reference numeral 20 denotes a nozzle of the transfer head, which sucks the chip 1 in vacuum. The transfer head vacuum suctions and picks up a chip 1 provided in a feeder (not shown) at its nozzle 20, and transfers the chip 1 above a light source unit 21 installed in an inclined posture. The display panel 5 is positioned on a movable table (not shown), and the display panel 5 is moved in an arbitrary direction by driving the movable table. Below the chip 1, the first
The camera 22 and the second camera 23 are installed. Two
Reference numerals 4 and 25 are optical fiber cables connected to the lens barrels 26 and 27, respectively.

In FIG. 3, K1 is the field of view of the first camera 22, and K2 is the field of view of the second camera 23. Field of view K1
The point A1 of the film carrier 2 and the point B1 of the transparent plate 6 can be captured at. Further, points A2 and B2 are captured in the visual field K2. The coordinates of each point are A1 (XA1, YA1),
A2 (XA2, YA2), B1 (XB1, YB1), B
2 (XB2, YB2). Therefore, Δd1 = XB
1-XA1 and Δd2 = XA2-XB2. In this way, the temporary attachment tool 9 is pressed against the film carrier 2 and temporarily attached in a state where the deviation between Δd1 and Δd2 is included. A
Before the main thermocompression bonding of 1 point and A2 point (before thermal expansion of the film carrier 2), the distance LT1 = LG− (Δd1 + Δd
2). As is clear from this equation, A before heat extension
The distance LT1 between one point and A2 point is shorter than LG. Note that L
G is a design value or an actual measurement value, as described above.

After the chip 1 is temporarily attached as described above, the main thermocompression bonding machine 14 performs the main thermocompression bonding. FIG. 4 is a perspective view of a main part of the main crimping machine 14. Reference numeral 30 denotes a tool for main pressure bonding, which includes a heater 31. The tool 30 is connected to a rod 33 of a cylinder 32. Cylinder 3
2 is provided on the bracket 34. Cylinder 32
Always biases the tool 30 downward. The guide rail 3 which is vertical to the back of the bracket 34
A slider 35 that slides along 6 is mounted. The guide rail 36 is mounted on the front surface of the box 37. A motor 38 is installed on the box 37. Although not shown in the figure, a vertical feed screw that is driven by a motor 38 to rotate is housed inside the box 37, and a nut that is screwed into this feed screw is mounted on the back surface of the bracket 34. . Therefore, the motor 38
The forward and backward rotation of the bracket moves the bracket 34 and the tool 30 up and down.

Reference numeral 39 is a pipe as a cooling means,
It is arranged along the front surface of the lower end of the tool 30 in the lowered position. The pipe 39 is provided with a plurality of small holes (not shown) at a pitch and blows cold air. When the chip 1 is thermocompression-bonded with the tool 30, by blowing cold air from the pipe 39 to cool the chip 1, thermal expansion of the chip 1 can be suppressed. The optical system shown by 21 to 26 is the same as the optical system shown in FIG.
Observe points A2, B2.

In FIG. 4, reference numeral 41 is a motor drive circuit, which controls the descending speed of the tool 30. Reference numeral 42 denotes a cold air supply unit, which controls switching between blowing out and stopping jetting of the cold air jetted from the pipe 39. Reference numeral 43 is a cylinder drive unit, which controls the crimping force of the tool 30. A heater drive circuit 44 controls the heater 31 to control the temperature of the tool 30. Reference numeral 45 denotes a main pressure bonding control unit, which controls each of the above-mentioned units according to the pressure bonding conditions shown in FIG. The main pressure control unit 45 is controlled by the computer 17 (FIG. 1) through the cable 18.

Next, the operation of the main pressure bonding machine 14 will be described. When the first chip 1 is permanently pressure bonded, the pressure bonding condition is set to condition 2 (standard). The display panel 5 to which the chip 1 is temporarily attached by the temporary press machine 13 is conveyed below the tool 30 as shown in FIG. The tool 30 is preheated to a high temperature of about 200 ° C. by driving the heater 31. When the motor 38 is driven there, the tool 30 descends and lands on the upper surface of the outer lead 4.
When the motor 38 is further operated and the bracket 34 is lowered, the pressing force of the cylinder 31 acts via the tool 30 to press the outer lead 4 against the electrode 8. Then, the ACF formed on the electrode 8 is hardened by heat. Next, the motor 38 is reversely rotated to raise the tool 30 to the original position. This completes the main thermocompression bonding of the outer leads 4.

After the main thermocompression bonding is completed, the first camera 22 and the second camera 23 use the points A1, B1 and A2.
Observe point B2. FIG. 5 shows the state after the main thermocompression bonding. As is clear from FIG. 5, assuming that the deviation between the A1 point and the B1 point is Δd1 ′ and the deviation between the A2 point and the B2 point is Δd2 ′, the after the main thermocompression bonding, The distance between points A1 and A2 is LT2 = LG
− (Δd1 ′ + Δd2 ′).

Next, a flow for changing the thermocompression bonding conditions based on the measured distance LT2 will be described with reference to FIG. This flow is performed under the control of the computer 17. First, in step 1, it is determined whether or not the distance LT2 is longer than LG by an allowable value α or more. If No, it is determined in step 2 whether the distance LT2 is shorter than LG by the allowable value α or more. If No, the distance of LT2 is within the allowable range and the outer lead 4 is correctly joined to the electrode 8. Therefore, the pressure bonding condition is not changed in step 3, that is, the condition 2 remains.

Yes in step 1 (film carrier 2
7), the thermocompression bonding conditions in step 4 are shown in FIG.
The condition is changed to condition 3, and in step 5, a condition change command is sent. As for condition 3, as shown in FIG. 7, the temperature of the tool 30 is raised, the crimping load of the tool 30 is increased, the crimping time is shortened, and the descending speed of the tool 30 remains unchanged (standard value).
Is maintained and cooling is performed. By executing this condition 3, thermal expansion of the film carrier 2 is suppressed,
Bring A1 and A2 points closer to B1 and B2 points,
The coupling between the outer lead 4 and the electrode 8 can be improved.

If Yes in Step 2 (insufficient extension of the film carrier 2), the pressure bonding condition is changed to Condition 1 in Step 6, and the command is sent in Step 5. As for condition 1, as shown in FIG. 7, the temperature of the tool 30 is maintained as it is (standard value), the crimping load is lowered, the crimping time is lengthened, the descending speed of the tool 30 is reduced, and the cooling is turned off.
To When this condition 1 is executed, the film carrier 2
Of the outer lead 4 and the electrode 8 can be improved by bringing the points A1 and A2 closer to the points B1 and B2, respectively.

Next, another method of the present invention will be described. If the distance LT1 before pressure bonding and the distance LT2 after pressure bonding are known, the elongation rate k of the film carrier 2 of the chip 1 in the currently used display panel assembly line can be known. k is as follows.

K = LT2 ÷ LT1 The distance LT2 after the main thermocompression bonding is best matched with the design value LG. Therefore, the optimum size of the film carrier 2 before pressure bonding is determined from the value of k. For example, after main thermocompression bonding, L
The optimum distance LU between the A1 point and the A2 point where T2 = LG is as follows.

LU = LG1 / k That is, the best display panel 5 can be assembled by making the chip 1 with a value obtained by multiplying the current size of the film carrier 2 by 1 / k and assembling it on this line. . Therefore, the computer 17 calculates the value of k and displays it on the monitor.
The value of k is fed back to the chip design to create a film carrier tape (material for the film carrier 2) suitable for an assembly line.

Although the above embodiment has been described by taking the display panel as an example, the substrate on which the chip is mounted may be other than the display panel.

[0033]

According to the present invention, it is possible to assemble a substrate such as a high quality display panel while controlling the apparatus so that the outer leads of the chip and the substrate such as the display panel are properly joined. In this case, B1 and B2 on the board
By using the positions of the points and the distance between them as the true value, it is possible to advantageously manage the distance between the points A1 and A2 of the film carrier. In addition, at the stage where the film carrier is temporarily attached to the substrate, the adequacy of the distance between the A1 point and the A2 point of the film carrier is judged, and if it is not possible, the main pressure bonding is stopped to greatly increase the substrate production yield. Can be improved.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a chip mounting apparatus according to an embodiment of the present invention.

FIG. 2 is a partial perspective view of a temporary crimping machine of a chip mounting apparatus according to an embodiment of the present invention.

FIG. 3 is a partial plan view of a chip and a display panel according to an embodiment of the present invention.

FIG. 4 is a perspective view of a main crimping machine of a chip mounting apparatus according to an embodiment of the present invention.

FIG. 5 is a partial plan view of a chip and a display panel according to an embodiment of the present invention.

FIG. 6 is a flowchart of the operation of the thermocompression bonding method of the chip mounting apparatus according to the embodiment of the present invention.

FIG. 7 is a table for setting thermocompression bonding conditions according to an embodiment of the present invention.

FIG. 8 is an explanatory view of a conventional thermocompression bonding method for outer leads of a chip.

[Explanation of symbols]

 1 Chip 2 Film Carrier 4 Outer Lead 5 Display Panel 6, 7 Transparent Plate 8 Electrode 9 Temporary Attaching Tool 13 Temporary Crimping Machine 14 Main Crimping Machine 30 Tool A1, B1 (First Mark) A2, B2 (Second Mark) )

Claims (5)

[Claims] 1. A thermocompression bonding method of a chip in which a bare chip is bonded to a film carrier by thermocompression bonding to a substrate. After the thermocompression bonding, the first mark and the second mark of the film carrier are observed by a camera. A thermocompression bonding method for a chip, characterized in that the distance between the two marks of the lever is obtained, and the thermocompression bonding conditions are changed based on the magnitude of the obtained distance. 2. The display panel, wherein the substrate is a transparent plate, and the distance is determined with the positions of the first mark and the second mark provided on the edge of the display panel as true positions. The thermocompression bonding method for a chip according to claim 1, wherein: 3. The thermocompression bonding method for a chip according to claim 1, wherein the thermocompression bonding conditions include at least one of temperature of the tool, pressure bonding load, pressure bonding time, descending speed, and cooling control. . 4. A thermocompression bonding method for a chip, wherein a chip formed by bonding a bare chip to a film carrier is thermocompression bonded to a substrate, wherein the film carrier is provided with a space before the thermocompression bonding of the film carrier to the substrate. Optically measuring the distance between the first mark and the second mark;
A step of optically measuring the distance between the first mark and the second mark after thermocompression bonding the film carrier to the substrate and bonding the outer leads provided on the film carrier to the electrodes provided on the substrate; A thermocompression bonding method for a chip, comprising: a step of calculating a ratio of the two measured distances to obtain an elongation rate of a film carrier; and a step of feeding back the elongation rate to a film carrier design process. 5. The thermocompression bonding method for a chip according to claim 4, wherein the thermocompression bonding is performed with the film carrier temporarily attached to the substrate.