JP2004095747A - Bonding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To vibrate and press-fit an electronic component such as an IC chip on a resin substrate such as a COF tape. <P>SOLUTION: Vibration is impressed not only to an IC chip 12 but also to a COF tape 11, and the IC chip 12 is pressurized to the COF tape 11 so that the IC chip 12 can be press-fit and bonded to the COF tape 11 while two vibration is impressed. The frequency of vibration to be impressed to the IC chip 11 is made larger than the frequency of vibration applied to the COF tape 11, and the former amplitude is made smaller than the latter amplitude. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bonding method for press-fitting an electronic component to a flexible plastic substrate.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, devices that apply vibration to join electronic components to a ceramic substrate have been widely used. The number of transducers used in these devices is usually one. The ceramic substrate is hard and hardly deforms even when subjected to vibration. Therefore, if the ceramic substrate is physically fixed, it does not move following the vibration of the electronic component. As a result, relative movement occurs between the electronic component and the ceramic substrate, and good frictional joining can be achieved. However, when there is only one vibrator, the vibration direction becomes one, so that there is a disadvantage that the shape of the joint becomes an ellipse long in the vibration direction. As a technique for solving this drawback, a technique in which two vibrators are used to make the vibration directions two directions is disclosed in Japanese Patent Application Laid-Open No. H11-284028.
[0003]
Japanese Patent Application Laid-Open No. H11-284028 relates to a bonding method and an apparatus for flip-chip bonding an electronic component such as a SAW element, and relates to a gold bump formed on a ceramic substrate and an electronic component such as a SAW element. A technique is disclosed in which a pressed gold bump is pressed while being heated. The configuration has a first vibrator that applies vibration to the ceramic substrate and a second vibrator that applies vibration to the electronic component. By applying ultrasonic waves from a plurality of directions using these two vibrators, The present invention is characterized in that the shape of the joining portion is made to be more circular by preventing the shape from becoming elongated. However, JP-A-11-284028 does not disclose a technique for joining an electronic component to a flexible resin substrate.
[0004]
On the other hand, for electronic products, TCP (Tape Carrier Package), which is easy to make a package thin, is frequently used in order to reduce the thickness. As a TCP manufacturing method, there are a TAB (Tape Automated Bonding) method and a COF (Chip On Flexible Circuit Board or Chip On Film) method. Above all, the COF method is frequently used for flip chip mounting. However, since the film on which the IC chip is mounted (synonymous with tape) is flexible, it has not been possible to press and join electronic components such as IC chips. For this reason, the method of joining an electronic component to a tape by the COF method includes soldering, Au-Sn, anisotropic conductive film (ACF), anisotropic conductive paste (ACP), and an NCP (non-conductive paste) for NCP (non-conductive paste). ing.
[0005]
[Problems to be solved by the invention]
Since the flexible resin substrate is a soft material, it has a problem that it is easily deformed when subjected to vibration. In other words, when the electronic component is to be fixed to the resin substrate, the portion where the resin substrate is in contact with the electronic component moves following the vibration of the vibrator even if the periphery thereof is pressed by the pressing mechanism. I will. Therefore, the relative movement (friction) between the surface of the electronic component and the surface of the resin substrate pressed against the electronic component is reduced by half. In particular, in the case of a vibration mode in which the frequency of vibration is high and the amplitude is as small as several tens of microns or less, this tendency becomes strong.
[0006]
For this reason, in the conventional method having one vibrator, even if the electronic component is vibration-pressed to the resin substrate, the bonding strength is extremely low and cannot be put to practical use. Further, the method of using two vibrators and vibrating both the electronic component and the resin substrate has a higher pressure contact strength as compared with the case of one vibrator, but has large variations and is not practical. For this reason, the method of joining an electronic component and a resin substrate by pressure welding has not been put to practical use.
[0007]
In addition, the various bonding methods described above have a problem that the bonding strength and the reliability of the quality are inferior to the bonding by pressure welding. For example, in the Au-Sn junction method, the solid-phase diffusion temperature is high and the thermal stress is large, so that the combination of target components that can be mounted is greatly restricted. As described above, when the conventional pressure welding method of applying vibration is applied to the COF method, there is a problem in the variation of the bonding strength, and it has not been practical.
[0008]
The present inventor uses a flexible resin substrate for thinning, and in order to find a method that does not cause variation even when an electronic component is fixed to this resin substrate by pressure welding, pressure bonding when two vibrators are used. The variation in strength was analyzed and studied. As a result, they have found that there is a certain law between the press-contact strength and the frequencies of the two vibrators. Furthermore, it has been found that there is a certain law between the pressure contact strength and the amplitude of each of the two vibrators with respect to the crimp strength. The present invention has been made based on this new finding.
[0009]
That is, an object of the present invention is to provide a method for pressure-bonding an electronic component such as an IC chip to a flexible tape or a flexible substrate with high bonding strength in view of the various problems described above.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a bonding method for press-fitting an electronic component held by a vibrating head to a resin substrate, wherein the electronic component is fixed to the vibrating head, and the electronic component is moved to a first predetermined position. Moving the resin substrate to a second predetermined position, holding the resin substrate on a substrate mounting table, bringing the electronic component close to the resin substrate, and adjusting the frequency of vibration of the vibrating head vibrator. Exciting the vibrating head vibrator and the substrate vibrator to bring the electronic component into pressure contact with the resin substrate under the condition that the frequency is higher than the vibration frequency of the substrate vibrator, and separating the electronic component from the vibrating head. And a step of separating the resin substrate fixed to the substrate mounting table from the substrate mounting table.
[0011]
When the frequency of the vibration applied to the resin substrate from the substrate oscillator decreases, the vibration efficiently reaches the press-contact surface between the resin substrate and the electronic component. On the other hand, the vibration of the electronic component vibrating head has a limit, but even at a high frequency, efficiently reaches the pressure contact surface between the resin substrate and the electronic component. In order to apply a large vibration energy to the pressure contact surface between the resin substrate and the electronic component, it is extremely effective to make the vibration frequency of the vibration head higher than that of the substrate vibrator.
[0012]
Also, the present invention provides a bonding method for pressing and joining an electronic component held by a vibration head to a resin substrate, wherein the step of holding the electronic component on the vibration head, the step of moving the electronic component to a first predetermined position, Sending the board to the second predetermined position, fixing the resin board to the board mounting table, bringing the electronic component close to the resin board, and adjusting the amplitude of the vibration of the board vibrator to the vibration of the vibrating head vibrator A step of exciting the electronic component and the resin substrate by pressing under a condition that the amplitude is larger than the amplitude of the electronic component, a step of separating the electronic component from the vibration head, and a step of mounting the resin substrate adsorbed and fixed to the substrate mounting table. And a step of separating from the substrate.
[0013]
Polyimide resins and PET resins are frequently used for COF tapes, and the attenuation of vibration is significantly greater than that of ceramics. Further, since resin is easily deformed, transmission efficiency is poor not only in longitudinal vibration but also in horizontal vibration. Applying a well-balanced vibration to the joint surface between the resin substrate and the vibration head by making the amplitude of the substrate vibrator that vibrates resin with large vibration attenuation and poor transmission efficiency larger than that of the vibration head Can be.
[0014]
Also, when the resin is thick like a vibration isolator, vibration is difficult to be transmitted, but when the thickness of the resin substrate is reduced, the vibration is transmitted to some extent. When the thickness of the resin substrate is 10 to 200 microns, the vibration is sufficiently transmitted to the pressure contact surface between the resin substrate and the electronic component, so that the pressure contact strength can be increased. Further, when the distance between the inner side of the square of the opening of the board holding plate and the electronic component is 0.5 to 5 mm, the vibration is sufficiently transmitted to the press contact surface between the resin substrate and the electronic component, so that the press contact strength is increased. can do.
[0015]
Further, by employing a TAB tape or a COF tape for the resin substrate, it becomes possible to manufacture TCP.
[0016]
In addition, by heating at least one of the electronic component and the resin substrate, the pressure contact strength between the electronic component and the resin substrate can be further increased.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a bonding method according to the present invention will be described in detail with reference to the drawings.
[0018]
FIG. 1 is a diagram showing main components of a bonding apparatus that performs the bonding method of the present invention. In the figure, reference numeral 1 denotes a bonding device, 2 denotes a vibration head for an electronic component, 2a denotes a vibration horn, 2b denotes a vibration head press-contact portion, 2c denotes a vibration head vibrator, 3 denotes a substrate vibration head, and 3a denotes a substrate vibrator. 4 is a heat insulating layer, 5 is a substrate heating unit, 6 is a substrate mounting table, 7 is a heater, 8 is a temperature sensor, 9 is a vacuum suction hole, 10 is a vacuum pipe, 11 is a COF tape which is a flexible resin substrate, 12 Denotes an IC chip serving as an electronic component, and 13 denotes a board holding plate.
[0019]
The bonding apparatus 1 has a structure in which an IC chip 12 and a COF tape 11 are pressed against each other by an electronic component vibrating head 2 which is a vibrating head provided vertically and a vibrator head 3 for a substrate. The electronic component vibrating head 2 includes a vibrating horn 2a, a vibrating head press-contact portion 2b provided on the bottom surface of the tip of the vibrating horn 2a, and a vibrating head vibrator 2c made of a piezoelectric element. The vibrating head press contact portion 2b is made of a super hard material, but is not particularly limited to this. This is because, when the surface of the vibrating head press contact portion 2b is coated with titanium nitride, carbon titanium, or the like, the durability is significantly improved regardless of the base material.
[0020]
The vibration of the vibrating head vibrator 2c propagates through the vibrating horn 2a and converges on the vibrating head pressing portion 2b. The vibration horn 2a is mounted at an angle with respect to the horizontal plane in order to make the vertical component of the vibration of the vibration head pressure contact portion 2b zero. As a result, the vibrating head press contact portion 2b vibrates only in the horizontal direction parallel to the COF tape 11. The vibration frequency is 10 to 60 KHz. A drive mechanism for moving the vibration head 2 for electronic components up and down, left and right is provided for suction and positioning of the IC chip 12, escape from the camera unit 17 and escape from the COF tape 11.
[0021]
Similarly to the vacuum suction holes 9 provided in the substrate mounting table 6, the vibration horn pressure contact portion 2b is provided with suction holes having a diameter of 0.8 mm for vacuum-sucking the IC chip 12 (not shown). . Further, a heater may be embedded in the vibration horn 2a as in the case of the substrate heating unit 5.
[0022]
The substrate vibration head 3 includes a function of applying the vibration excited by the substrate vibrator 3a to the COF tape 11, a function of adsorbing and holding the COF tape 11, and a function of heating the COF tape 11. I have. A giant magnetostrictive element that expands and contracts in response to an externally applied magnetic field is used as the substrate vibrator 3a. The vibration frequency is 10 to 30 KHz. Giant magnetostrictive materials are sensitive to heat. Therefore, the heat insulating layer 4 is provided between the substrate vibrator 3 a and the heating unit 5 to prevent the substrate vibrator 3 a from being overheated by the heat generated in the substrate heating unit 5. Note that a giant magnetostrictive element is an element that excites high-frequency vibrations like a piezoelectric element, and has excellent characteristics in a low frequency range as compared with a piezoelectric element. On the other hand, in the bonding technology area for electronic components, a giant magnetostrictive element can be replaced by a piezoelectric element, and vice versa.
[0023]
The heat insulating layer 4 is mainly made of a porous ceramic. Porous ceramics are heat insulating materials that are superior in overall characteristics such as high temperature resistance, low vibration damping characteristics and relatively high strength characteristics as compared with other materials.
[0024]
The substrate heating section 5 is provided between the heat insulating layer 4 and the substrate mounting table 6. The substrate heating section 5 is provided with a heater 7, a temperature sensor 8, and a vacuum pipe 10 connected to a vacuum source. The heat from the substrate heating section 5 is designed to be hardly conducted to portions other than the substrate mounting table 6. The heater 7 is a sheath heater, and the temperature sensor 8 is a thermocouple.
[0025]
The board mounting table 6 has a function of receiving a load at the time of pressing and a function of transmitting heat to the COF tape 11 in addition to a function of mounting and adsorbing and fixing the COF tape 11 serving as a resin substrate.
[0026]
The vacuum suction hole 9 has a square shape surrounding the IC chip 12, and is indicated by two grooves on both sides in FIG.
[0027]
The substrate vibration head 3 can be moved vertically so that the substrate mounting table 6 does not come into contact with the COF tape 11 when the COF tape 11 is fed.
[0028]
As shown in FIG. 2, a square opening 14 is provided in the center of the substrate holding plate 13. The opening 14 is designed so that the bottom surface of the distal end portion of the vibration head 2 for electronic components and the vibration head pressure contact portion 2b can enter. The outer periphery of the opening 14 has a large surface to prevent contact with the substrate vibration head 3.
[0029]
Further, when the COF tape 11 is fed, the board holding plate 13 can move in a vertical direction so as not to contact and damage the electrical connection terminal portions 16 (see FIG. 3) formed on the COF tape 11. It has become. Further, when the COF tape 11 is pressed and fixed by the substrate pressing plate 13, the electric connection terminal portion 16 formed on the COF tape 11 and the IC chip 12 pressed and joined to the COF tape 11 are released.
[0030]
The COF tape 11 is fixed to the substrate mounting table 6 by the vacuum suction holes 9 and the substrate holding plate 13. On the other hand, the press-contact surface (the upper surface in FIG. 1) of the COF tape 11 is separated from the substrate mounting table 6 by the thickness of the COF tape 11. The COF tape 11 is flexible, and even if the COF tape 11 is fixed by the substrate pressing plate 13, the press-contact surface of the COF tape 11 cannot be completely fixed like a hard ceramic substrate.
[0031]
Further, in the COF tape 11, the degree of fixing of the press contact surface largely depends on the distance between the substrate pressing plate 13 and the IC chip 12 in addition to the thickness of the tape. The function of the vacuum suction hole 9 is mainly to fix the COF tape 11. The COF tape 11 is also fixed by suction through the vacuum suction holes 9, but mainly the holding of the substrate holding plate 13 fixes the COF tape 11. 1 and 2, the distance between the substrate holding plate 13 and the IC chip 12 is shown large for easy viewing, but this distance is made as small as possible within a range not in contact with the vibration head 2 for electronic components. Is preferred. The distance from the end of the opening 14 to the IC chip 12 to be pressed is 1.5 mm. Preferably it is 0.5-5 mm, more preferably 0.8-2 mm.
[0032]
Further, the vibration direction of the vibrating head press contact portion 2b is orthogonal to the vibration direction of the substrate mounting table 6. When orthogonal, the two vibrations will not cancel the amplitude. Furthermore, by making the frequencies of the vibrations different, the combined vector of the two vibrations takes not only a fixed direction but also a random direction.
[0033]
When the vibration frequency of the vibrating head vibrator 2c is 40 KHz, the amplitude of the vibration horn 2a is about 3 microns, the amplitude of the IC chip 12 is 1.8 microns, and the amplitude attenuates to about 60%. When the vibration frequency of the vibrating head vibrator 2c is 60 KHz, the amplitude of the vibration horn 2a is about 1 micron, the amplitude of the IC chip 12 is 0.2 micron, and the amplitude attenuates to about 20%. As the vibration frequency increases, the vibration energy increases, but the transmission loss increases. Therefore, the vibration frequency is determined in consideration of vibration attenuation.
[0034]
FIG. 2 is a plan view showing the relationship between the COF tape 11 and the substrate holding plate 13. Perforations for feeding are drilled at both ends of the COF tape 11, and a wiring (not shown) and an electrical connection terminal 16 are formed at the center. The COF tape 11 is fed in the direction of the arrow in FIG. The substrate holding plate 13 is provided with one opening 14 and two notches 15 (one side of the opening is open). The opening 14 is for receiving the vibrating head press contact portion 2b, and the plane size of the opening 14 is preferably closer to the plane size of the IC chip 12. Further, the notch 15 is a relief portion for preventing the electric connection terminal portion 16 provided on the COF tape 11 from contacting the IC chip 12. Since the COF tape 11 is flexible, the substrate holding plate 13 is not limited to the periphery of the IC chip 12 to be pressed and is 2 to 7 times the mounting pitch of the IC chip 12 so that the COF tape 11 can be stably held down. It has a shape that can be widely held down.
[0035]
FIG. 3 shows a camera unit 17 that picks up an image of the IC chip 12 that has been moved to a predetermined position after being attracted to the vibrating head pressure contact portion 2b and the electric connection terminal portion 16 of the COF tape 11 that has been sent to the predetermined position. This is shown in order to explain the step of performing the positioning. The IC chip 12 is attracted to the vibration head press contact portion 2b disposed at the bottom of the tip of the vibration horn 2a.
[0036]
A ring illumination 29 (see FIG. 8) is provided around the opening 14 of the camera unit 17, and the IC chip 12 is imaged by the camera unit 17 by receiving the light. Flash imaging can be performed using the ring illumination 29. Similarly, the camera unit 17 captures an image of the unconnected electrical connection terminal 16 provided on the COF tape 11. The COF tape 11 shows the unconnected electrical connection terminals 16 and the IC chip 12 pressed into contact with the COF tape 11, and an arrow is shown as the feed direction of the COF tape 11.
[0037]
4A and 4B are diagrams illustrating the configuration of the camera unit 17, wherein FIG. 4A is a plan view, FIG. 4B is a side view, and FIG. 4C is a front view. The camera unit 17 is composed of two camera units so that upper and lower images can be taken. The camera unit 17 includes an optical system 18 and an imaging unit 19. Further, the optical system 18 is divided into two systems, one of which is obtained by capturing an image of the electric connection terminal section 16 on the COF tape 11 from the camera opening 20, refracting the image by 90 degrees by the prism 21, and further refracting the image by 90 degrees by the mirror 22. Bend and input to CCD23.
[0038]
The imaging unit 19 converts the image input to the CCD 23 into an electric signal, and transmits the signal to the image processing device 32 (see FIG. 8). Arrows indicate the traveling direction of light. Similarly, the other optical system 18 captures the image of the IC chip 12 adsorbed on the vibrating head press-contact portion 2 b from the camera opening 20, bends it 90 degrees by the prism 21, further bends it 90 degrees by the mirror 22, and inputs it to the CCD 24. . Then, the imaging section 19 converts the image input to the CCD 24 into an electric signal, and transmits the signal to the image processing device 32. FIG. 4B shows the upper and lower camera apertures 20 and the prism 21. The upper and lower images are fetched from the respective camera apertures 20, transmitted by the optical system 18 arranged on the same plane, and converted into digital signals by the CCDs (23, 24).
[0039]
On the other hand, the electronic component vibrating head 2 is aligned with the COF tape 11, and is lowered to press the COF tape 11 after the camera unit 17 is retracted. Normally, when the electronic component vibration head 2 is moved in the vertical direction after the positioning with the COF tape 11, the positioning accuracy is reduced. In order to prevent this reduction in alignment accuracy, it is effective to shorten the moving distance. In the present embodiment, the thickness near the camera opening 20 is reduced. As means for reducing the thickness of the camera unit 17 in the vicinity of the camera opening 20, two optical systems 18 may be arranged on the same plane, or the optical system 18 and the image pickup unit 19 may be separated so that the optical system 18 is imaged. It is preferable to make it thinner than the part 19.
[0040]
Note that a position mark (alignment mark) is used for an image for positioning the COF tape 11. A circuit wiring pattern is used for positioning the IC chip 12. When a circuit board is bonded to the COF tape 11 instead of the IC chip 12, a position mark is used. The shape of the position mark is a circle having a diameter of 0.2 mm. Other shapes such as a square and an X mark may be used, and the dimension is preferably 0.1 to 5 mm.
[0041]
FIG. 5 is a flowchart relating to the alignment between the electronic component (here, the IC chip 12) and the electrical connection terminal portion 16 on the resin substrate (here, the COF tape 11).
[0042]
First, the step of fixing the IC chip 12 to the electronic component vibration head 2 is started. That is, the electronic component vibrating head 2 is moved onto a tray (not shown) in which the IC chip 12 is placed, and the IC chip 12 is suction-fixed to the vibrating head press-contact portion 2b (step 1). The tray may be a wafer substrate backed by a tape and cut.
[0043]
Next, the process proceeds to a step of moving the IC chip 12 to the first predetermined position. That is, in order to move the IC chip 12 to the pressure contact position (first predetermined position) with the COF tape 11, the electronic component vibration head 2 to which the IC chip 12 is fixed by suction is moved (step 2).
[0044]
Next, the process proceeds to the step of feeding the COF tape 11 to the second predetermined position. That is, the COF tape 11 is fed in a free state where the COF tape 11 is separated from the substrate mounting table 6 and the substrate holding plate 13, and the COF tape 11 is moved to a pressure contact position (second predetermined position) with the IC chip 12 (step). 3).
[0045]
Next, the process proceeds to a step of holding the COF tape 11 on the substrate mounting table 6. That is, the substrate mounting table 6 is raised, and the COF tape 11 is sucked to the substrate mounting table 6 using the vacuum suction holes 9 (step 4). In addition, the board holding plate 13 is lowered to fix the COF tape 11 between the board mounting table 6 and the board holding plate 13 (step 5). Thereby, the COF tape 11 is held on the substrate mounting table 6.
[0046]
Next, the process proceeds to the step of aligning the IC chip 12 and the COF tape 11. First, the camera unit 17 is moved to a position where the position mark can be imaged (step 6). Then, an image of the position mark of the COF tape 11 and an image of the position mark of the IC chip 12 are simultaneously picked up and taken into the camera unit 17 (step 7).
[0047]
Next, the coordinates of the position mark on the COF tape 11 and the coordinates of the position mark on the IC chip 12 are calculated (step 8). If the error of the coordinates related to the position mark of the COF tape 11 or the position mark of the IC chip 12 is out of the predetermined range (YES in Step 9), the electronic component vibrating head 2 is moved to perform the alignment (Step 10). If the error in the coordinates of the captured position mark is within the predetermined range (NO in step 9), the electronic component vibrating head 2 is not moved, and the process proceeds to the next step.
[0048]
In this embodiment, since the image of the position mark on the COF tape 11 is directly captured (without passing through the tape or the transparent substrate), the position reading accuracy is not reduced due to the optical distortion of the transparent substrate. Position detection position accuracy can be improved.
[0049]
When the coordinates of the two components are measured separately, the errors in the coordinates from the respective origins are added to the alignment accuracy of the two components. On the other hand, as described above, if the positions of two components are measured at the same time, only the relationship between the two measurement positions is necessary, and the error of the coordinates from the origin of the two components has no relationship. In other words, even when the camera unit 17 is moving, the alignment data of the two parts can be taken in with high accuracy. Such simultaneous imaging is an effective method for open control, which is a position control method that does not detect residual vibration.
[0050]
The camera unit 17 moves to the imaging position of the position mark for each alignment and images the position mark. When the IC chip 12 is pressed against the COF tape 11, the camera unit 17 is retracted from the imaging position. It is difficult to completely stop the camera unit 17 in a short time, and residual vibration remains. When the residual vibration is somewhat large, if the position mark of the IC chip 12 and the position mark on the COF tape 11 are separately imaged, the coordinates of the measured and calculated position mark include the influence of the residual vibration. However, the above-described problem does not occur if the IC chip 12 is simultaneously imaged with reference to the position mark of the COF tape 11. When the position mark on the IC chip 12 and the position mark on the COF tape 11 are simultaneously imaged by the same camera unit 17, the residual vibration of the camera unit 17 has almost no problem. As described above, when the method according to the present embodiment is employed, the accuracy of image alignment is significantly improved. Also, in step 6 described above, by simultaneously capturing the upper and lower images, the time for waiting for a decrease in residual vibration for capturing the image can be shortened, resulting in a reduction in tact time.
[0051]
FIG. 6 is a flowchart relating to a method of bonding the bump electrodes of the IC chip 12 to the electric connection terminals 16 on the COF tape 11.
[0052]
Steps 1 to 10 are almost the same as the flowchart relating to the alignment between the IC chip 12 and the COF tape 11. In this case, the simultaneous imaging in step 6 is not an essential requirement.
[0053]
Hereinafter, the steps after the alignment will be described with reference to FIG.
[0054]
First, the camera unit 17 for positioning is retracted (step 11). At this time, the temperature of the vibration horn 2a is 300 ° C. The temperature of the substrate heating section 5 is 200 ° C. In addition, heating may be performed only by the substrate heating unit 5.
[0055]
Next, a step of lowering the electronic component vibration head 2 to bring the IC chip 12 close to the COF tape 11 is performed (step 12).
[0056]
Next, under the condition that the vibration frequency of the vibrating head vibrator 2c is higher than the vibration frequency of the substrate vibrator 3a, the vibrating head vibrator 2c and the substrate vibrator 3a are excited to cause the IC chip 12 to vibrate. And pressing the COF tape 11 against the COF tape 11. More specifically, under the condition that the frequency of the vibrating head vibrator 2c is 40 KHz and the frequency of the substrate vibrator 3a is 18 KHz, the vibrating head vibrator 2c and the substrate vibrator 3a are excited (step 13). ). At this time, the amplitude of the vibrating head press contact portion 2b is 8 microns, and the amplitude of the substrate mounting table 6 is 14 microns. Further, the IC chip 12 is pressed against the electric connection terminal 16 of the COF tape 11 for 0.5 seconds (step 14). The dimensions of the IC chip 12 are 2 × 10 mm, the thickness is 0.4 mm, and the number of terminals (bumps) is 40. The pressure contact load is approximately 100 grams / bump, and the total is 40N.
[0057]
Next, a step of separating the IC chip 12 from the vibration head 2 is performed. Specifically, the vacuum holding the IC chip 12 is broken to separate the vibrating head press-contact portion 2b from the IC chip 12 (step 15).
[0058]
Next, a step of separating the COF tape 11 fixed to the substrate mounting table 6 from the substrate mounting table 6 is performed. More specifically, the vacuum break sucking the COF tape 11 and the lifting of the substrate holding plate 13 are performed to make the COF tape 11 free (step 16). In addition, the electronic component vibrating head 2 is moved to a position where the IC chip 12 is picked up.
[0059]
Next, the substrate mounting table 6 is lowered (step 17). Next, the COF tape 11 is fed by one pitch, and the next bonding operation is started (step 18).
[0060]
In this embodiment, the frequency of the vibrating head vibrator 2c is higher than the frequency of the substrate vibrator 3a. The amplitude of the vibration is opposite to the frequency, and the amplitude of the substrate oscillator 3a is larger than the amplitude of the oscillation head oscillator 2c.
[0061]
When the frequency of the vibrating head vibrator 2c is lower than the frequency of the substrate vibrator 3a, the energy efficiency is deteriorated and it is difficult to obtain a good pressure contact strength. This is because the higher the frequency applied to the COF tape 11, the greater the loss transmitted to the press-contact surface of the COF tape 11. On the other hand, since the amplitude of the IC chip 12 is small, it is better to increase the energy by increasing the frequency to some extent. For this reason, the frequency of the vibrating head vibrator 2c is preferably 1.2 to 4 times the frequency of the substrate vibrator 3a. More preferably, it is 1.5 to 2.5 times.
[0062]
In the present invention, experiments were performed with the vibration head vibrator 2c having an amplitude of 2 to 12 microns and the substrate vibrator 3a having an amplitude of 3 to 20 microns. In order to make the amplitude of the vibrating head vibrator 2c larger than the amplitude of the substrate vibrator 3a, it is necessary to lower the frequency of the vibration, which degrades energy efficiency and makes it difficult to obtain good pressure contact strength. The amplitude of the vibrating head vibrator 2c is preferably 1 / 1.2 to 1/4 times the amplitude of the substrate vibrator 3a. More preferably, it is 1 / 1.5 to 1 / 2.5.
[0063]
When the frequency of the vibration horn 2a is 40 kHz, the amplitude of the vibration horn 2a is about 3 microns, and the amplitude of the IC chip 12 is about 1.8 to 70%, which is attenuated to about 60 to 70% of the vibration horn 2a. 2 microns. On the other hand, when the frequency of the vibration horn 2a is 60 kHz, the amplitude of the vibration horn 2a is about 1 micron, and the amplitude of the IC chip 12 is about 0.2 micron which is attenuated by about 20% with respect to the vibration horn 2a. Met. Accordingly, when the frequency of the vibration horn 2a is about 40 kHz, the amplitude of the vibration horn 2a is larger and the attenuation of the vibration transmitted to the IC chip 12 is smaller than when the frequency of the vibration horn 2a is about 60 kHz. The energy loss applied to the junction of the chip 12 is reduced.
[0064]
The timing of the start of the excitation of the vibrators 2c and 3a and the start of the pressing of the IC chip 12 may be earlier or later than the start of the excitation of the vibrators 2c and 3a. More preferably, the start of excitation of each of the vibrators 2c and 3a and the start of pressing of the IC chip 12 are simultaneous.
[0065]
FIG. 7 shows the relationship between the thickness of the COF tape 11 and practicality. The used COF tape 11 is a polyimide resin having a thickness of 40 microns. When the pressure contact strength is high enough to withstand practical use, it is indicated by ○, when it is low, it is indicated by x, and when it is intermediate, it is indicated by △. Similarly, when the tape strength can withstand practical use, it is indicated by ○, when the tape strength cannot be endured, ×, and when the tape strength is intermediate, Δ is indicated. The evaluation of the product is indicated by ○ when the product passes, × when the product fails, and Δ when the product is intermediate. The preferred thickness of the COF tape 11 is 10 to 200 microns. A more preferred thickness of the COF tape 11 is 20 to 70 microns.
[0066]
FIG. 8 mainly shows a positioning mechanism 25 for horizontally positioning the IC chip 12 attached to the bottom surface of the tip of the electronic component vibration head 2 with respect to the COF tape 11 in the bonding apparatus 1. FIG. 4 is a block diagram of various elements.
[0067]
As shown in FIG. 8, the positioning mechanism 25 includes an X-axis table 26, a Y-axis table 27, a camera unit 17, a ring illumination 29, a device controller 30, a motor driver 31, and an image processing device 32. , A flash illumination control mechanism 33. The positioning mechanism 25 positions the IC chip 12 with respect to the COF tape 11, and moves the vibration horn 2a on which the IC chip 12 is sucked and held in the X-axis direction and the Y-axis direction.
[0068]
The X-axis table 26 is for controlling the driving of the vibration horn 2a in the X-axis direction, and has an encoder for detecting the position of the vibration horn 2a in the X-axis direction. The X-axis table 26 constantly sends position data of the vibration horn 2a in the X-axis direction to the device controller 30, the motor driver 31, and the image processing device 32.
[0069]
The Y-axis table 27 is for controlling the driving of the vibration horn 2a in the Y-axis direction, and has an encoder for detecting the position of the vibration horn 2a in the Y-axis direction. The Y-axis table 27 constantly sends position data of the vibration horn 2a in the Y-axis direction to the device controller 30, the motor driver 31, and the image processing device 32.
[0070]
The device controller 30 controls the operations of the X-axis table 26, the Y-axis table 27, the motor driver 31, the image processing device 32, and the flash illumination control mechanism 33. The device controller 30 controls the motor driver 31, the image processing device 32, and the flash based on the position data constantly transmitted from the X-axis table 26 and the Y-axis table 27 and the image data transmitted from the image processing device 32. The operation of the illumination control mechanism 33 is controlled. Further, the device controller 30 may periodically scan the position data and read the data intermittently.
[0071]
When the device controller 30 recognizes that the IC chip 12 has approached above a predetermined position in the horizontal direction of the COF tape 11 based on the position data from the X-axis table 26 and the Y-axis table 27, the device controller 30 sends an image to the image processing device 32. Send a command signal to capture At the same time, the device controller 30 sends a command signal to the flash illumination control mechanism 33 to irradiate the flash illumination.
[0072]
The motor driver 31 drives the vibration horn 2a in the X-axis direction and the Y-axis direction under the control of the device controller 30. The image processing device 32 performs image processing on a video image captured by the camera unit 17 under the control of the device controller 30. The image processing device 32 receives image data from the camera unit 17 and receives position data from the X-axis table 26 and the Y-axis table 27. Then, it receives a command signal from the device controller 30, controls the imaging operation of the camera unit 17, and sends a start signal to the flash illumination control mechanism 33 to start the flash illumination operation at the same time. Upon receiving two command signals from the image processing device 32 and the device controller 30, the flash illumination control mechanism 33 operates the ring illumination 29 to perform flash illumination.
[0073]
The positioning method described in FIG. 5 enables the improvement of the positioning accuracy of the electronic component such as the above-described IC chip 12 and the resin substrate such as the COF tape 11 on which the electronic component is mounted, and the shortening of the tact time. is there. The target substrate is not limited to a flexible resin substrate, but can be applied to a highly rigid resin tape, a resin substrate, and a ceramic substrate. Further, FIG. 5 shows an example in which two vibrators 2c and 3a are used, but it is obvious that the alignment method described in FIG. 5 can be applied to a case where there is only one vibrator.
[0074]
The present invention is also applicable to an apparatus using the bonding method of the present invention, which is a bonding apparatus including a part of the components shown in FIGS. Further, it is clear that the bonding method according to the present invention can be applied to COF products and TCP manufactured using this method.
[0075]
【The invention's effect】
According to the bonding method of the present invention, an electronic component such as an IC chip can be pressure-bonded to a flexible resin substrate with high strength. In addition, an electronic component such as an IC chip can be press-welded to a flexible COF tape, and a liquid crystal module can be industrially provided by a highly reliable COF mounting method.
[Brief description of the drawings]
FIG. 1 is a front view of main components of a bonding apparatus.
FIG. 2 is a diagram showing a relationship between a COF tape and a substrate holding plate.
FIG. 3 is a view for explaining a step of aligning an electronic component and a COF tape.
4 (a) is a plan view, FIG. 4 (b) is a side view, and FIG. 4 (c) is a front view.
FIG. 5 is a flowchart illustrating a method for aligning an IC chip and a COF tape.
FIG. 6 is a flowchart illustrating a manufacturing method for press-bonding an IC chip and a COF tape.
FIG. 7 is a diagram showing a relationship among a thickness of a flexible substrate, a press contact strength, a tape strength, and a product evaluation.
FIG. 8 is a block diagram of a positioning drive mechanism.
[Explanation of symbols]
1 Bonding equipment
2 Vibration head for electronic parts
2a Vibrating horn
2b Vibration head pressure contact part
2c Vibrator for vibrating head
3 Vibration head for substrate
3a Substrate vibrator
4 Thermal insulation layer
5 Substrate heating section
6 Board mounting table (board mounting table)
7 heater
8 Temperature sensor
9 Vacuum suction holes
10 Vacuum pipe
11 COF tape (resin substrate)
12 IC chip (electronic parts)
13 Board holding plate
14 opening
15 Notch
16 Electrical connection terminals
17 Camera unit
18 Optical system
19 Imaging unit
20 Camera opening
21 Prism
22 mirror
23, 24 CCD
25 Positioning mechanism
26 X table
27 Y table
29 Ring Light
30 Equipment controller
31 Motor driver
32 Image processing device
33 Flash illumination control mechanism

Claims (5)

In a bonding method of pressing and joining an electronic component held by a vibration head to a resin substrate,
Fixing the electronic component to the vibrating head,
Moving the electronic component to a first predetermined position;
Sending the resin substrate to a second predetermined position;
A step of holding the resin substrate on a substrate mounting table,
Bringing the electronic component close to the resin substrate,
Under the condition that the vibration frequency of the vibration head vibrator is higher than the vibration frequency of the substrate vibrator, the vibrating head vibrator and the substrate vibrator are excited and the electronic component and the resin substrate are separated from each other. Pressure contacting,
A step of separating the electronic component from the vibration head,
Separating the resin substrate fixed to the substrate mounting table from the substrate mounting table. In a bonding method of pressing and joining an electronic component held by a vibration head to a resin substrate,
Holding the electronic component on the vibrating head,
Moving the electronic component to a first predetermined position;
Sending the resin substrate to a second predetermined position;
Fixing the resin substrate to a substrate mounting table;
Bringing the electronic component close to the resin substrate,
A step of pressing the electronic component and the resin substrate to be excited under the condition that the amplitude of the vibration of the substrate vibrator is larger than the amplitude of the vibration of the vibration head vibrator,
A step of separating the electronic component from the vibration head,
A step of separating the resin substrate adsorbed and fixed to the substrate mounting table from the substrate mounting table,
A bonding method comprising: The bonding method according to claim 1, wherein the resin substrate has a thickness of 10 to 200 μm. 4. The bonding method according to claim 1, wherein the resin substrate is a COF tape or a TAB tape. 5. The bonding method according to claim 1, wherein at least one of the electronic component and the resin substrate is heated.

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