JP7780468B2 - Stamp holding means, stamp inspection device using the same, and chip transfer device - Google Patents

Description

The present invention relates to a stamp holding means for holding a stamp used when picking up chip components from a source substrate and transferring them to a destination substrate, as well as a stamp inspection device and a chip transfer device that use this stamp holding means.

As μLED displays become more widely used, there has been growing interest in chip transfer devices that pick up densely packed chip components on a source substrate, widen the pitch, and mount them on a destination substrate.

As such a chip transfer device, a method using a chip stamp that simultaneously attaches and detaches multiple chip components to and from an adhesive surface is known (see, for example, Patent Document 1).
As shown in the cross-sectional view of Figure 11(a), the stamp 2 has adhesive portions 21 provided on a plate-shaped stamp body 20, and the spacing between the adhesive portions 21 is an integer multiple of the pitch of the chip components C on the original substrate S0.

As shown in Figure 11(a), the stamp 2 held by the pick-up head 101 is aligned so that the chip component C is located directly below the adhesive portion 21, and then the adhesive portion 21 is brought into close contact with the chip component C as shown in Figure 11(b). At this stage, if the adhesive force of the adhesive portion 21 to the chip component C is greater than the adhesive force to the source substrate S0, the stamp 2 is raised (moved away from the source substrate S0), and the chip component C that is in close contact with the adhesive portion 21 is picked up from the source substrate S0 (Figure 11(c)).

The stamp 2 that has picked up the chip component C is held by the mounting head 102 and aligned with a predetermined location on the destination substrate S1 as shown in Figure 12(a), and then pressed against the destination substrate S1 as shown in Figure 12(b). At this stage, if the adhesive strength of the adhesive portion 21 to the chip component C is weakened by heating or other means to be weaker than the bonding strength to the destination substrate S1, then when the stamp 2 is raised (moved away from the destination substrate S1), the chip component C will be separated from the stamp 2 and mounted on the destination substrate S1 (Figure 12(c)). Here, heating the chip component C may weaken the adhesive strength of the adhesive portion 21 while strengthening the bonding strength between the chip component C and the destination substrate S1.

As described above, the stamp 2 transfers the chip component C picked up from the source substrate S0 to the destination substrate S1 with the chip component C attached to the adhesive portion 21 as shown in Figure 13(a), and after transfer, as shown in Figure 13(b), the chip component C is no longer attached to the adhesive portion 21. Figure 13(c) shows the configuration of a chip transfer device that performs this operation, and is equipped with a pickup device 5 and a mounting device 6.

In such a chip transfer device, chip components C should be held on all adhesive portions 21 in the pickup device 5, and all chip components C attached to the adhesive portions 21 should be transferred to the destination substrate S1 in the mounting device 6. However, in the pickup device 5, chip components C may not adhere to some of the adhesive portions 21, as shown in Figure 14(a). Also, in the mounting device 6, chip components C that could not be mounted on the destination substrate S1 may remain on the adhesive portions 21, as shown in Figure 14(b).

Overlooking phenomena such as those shown in Figures 14(a) and 14(b) would be a major problem in the chip transfer process, so it is preferable to place a stamp inspection device 7 between the pickup device 5 and the mounting device 6. The stamp inspection device 7 checks whether a chip component C is attached to a predetermined location (adhesive portion 21) on the stamp 2 in the state shown in Figure 13(a), and inspects whether any chip components C remain on the stamp 2 in the state shown in Figure 13(b).

Figure 16 shows the configuration of a typical visual inspection device used to observe the condition of the chip component holding surface of stamp 2. In Figure 16, the chip component holding surface of stamp 2 illuminated by light emitted by reflective light source 40 is photographed by camera 4, which serves as an imaging means, and the image is analyzed to determine whether or not chip components C are attached. For example, Figure 17(a) shows the state of the chip component holding surface after pick-up and before mounting, with the IRC corresponding to the portion holding chip components C being bright and the portion corresponding to adhesive portion 21 not holding chip components C being dark. Figure 17(b) shows the state of the chip component holding surface after mounting, and it can be seen that chip components C remain in the bright portions.

Japanese Patent Application Laid-Open No. 2019-175961

When performing inspections using the configuration shown in Figure 16, the state of the reflected image varies depending on the light intensity and orientation of the reflection light source 40, and attempting to determine the presence or absence of chip components C based on the brightness of the image makes it difficult to set a threshold, which can lead to incorrect determinations.

In particular, as chip components C become smaller and the number of chip components C attached to one stamp 2 increases, the number of pixels of the camera 4 per chip component C decreases, making accurate determination more difficult.

The present invention was made in consideration of the above-mentioned problems, and provides a stamp holding means used to accurately inspect whether a chip component is attached to a specified location on a stamp, even if the chip component is small, as well as a stamp inspection device and a chip transfer device that use this means.

In order to solve the above problem, the invention of claim 1 comprises:
A stamp holding means for holding a stamp,
The stamp uses its adhesiveness to simultaneously attach multiple chip components, transferring the chip components on the source substrate to the destination substrate.
A stamp holding means holds the side of the stamp opposite to the adhesive surface and irradiates the stamp with light.

The invention described in claim 2 is the stamp holding means described in claim 1,
a light-transmitting adsorption portion that adsorbs and holds the opposite side of the stamp's adhesive surface;
The stamp holding means includes an illumination unit that is disposed on the opposite side of the surface of the adsorption unit that adsorbs the stamp, and that irradiates light onto the stamp through the adsorption unit.

The invention described in claim 3 is the stamp holding means described in claim 2,
The suction unit is a stamp holding means having a translucent lower plate with suction holes, a translucent upper plate, and side plates, and is configured to form a reduced pressure space inside.

The invention described in claim 4 is the stamp holding means described in claim 2,
The adsorption portion is a stamp holding means having a porous region, and the porous region adheres closely to the stamp to adsorb and hold the stamp.

The invention described in claim 5 is a stamp inspection device comprising the stamp holding means described in any one of claims 1 to 4 and an imaging means for capturing an image transmitted through the stamp while irradiating the stamp with light.

The invention described in claim 6 is the stamp inspection device described in claim 5,
The stamp inspection device further comprises image processing means for determining whether or not a chip component is attached to a predetermined location on the stamp from the image acquired by the imaging means.

The invention described in claim 7 is
a pickup device that uses the stamp to simultaneously pick up a plurality of chip components on the transfer source substrate;
a mounting device that simultaneously mounts a plurality of chip components on the destination substrate;
A chip transfer device is provided with the stamp inspection device according to claim 5 or 6.

The invention described in claim 8 is the chip transfer device described in claim 7,
This is a chip transfer device that has a function in which the stamp inspection device inspects the stamp after the pickup operation has been performed by the pickup device, and a function in which the stamp inspection device inspects the stamp after the mounting operation has been performed by the mounting device.

This invention makes it possible to accurately determine whether or not a chip component is attached to a specified location on a stamp, even if the chip component is small.

3 is a cross-sectional view illustrating the configuration of a stamp holding means according to the embodiment of the present invention. FIG. 1A and 1B are schematic diagrams of a stamp holding means according to an embodiment of the present invention, showing (a) a state seen from above, (b) a state where no stamp is being held as seen from below, (c) a state where the stamp is approaching as seen from below, and (d) a state where a stamp is being held as seen from below. FIG. 2 is a cross-sectional view illustrating the configuration of a stamp holding means according to an embodiment of the present invention, showing an example in which an adsorption part has a reduced pressure space. 1 is a diagram showing an embodiment of a stamp inspection device using a stamp holding means of the present invention. 1A shows an example of an image when inspecting a stamp that has picked up a chip component using a stamp inspection device according to an embodiment of the present invention, and FIG. 1B shows an example of an image when inspecting a stamp after mounting a chip component. 10A and 10B are diagrams showing an example of a method for setting a reference for position information of a chip component in a stamp. FIG. 10 is a diagram showing an example of a stamp having a stamp recognition mark. FIG. 10 is a diagram illustrating an example of a device configuration for acquiring position information of a stamp recognition mark. 10 is a diagram showing an example of an image obtained when inspecting a stamp that has picked up a chip component using a stamp inspection device according to an embodiment of the present invention, in which a suction hole in a lower plate of the suction part is reflected. FIG. 1A and 1B are schematic diagrams of a stamp holding means according to a modified embodiment of the present invention, in which (a) shows a state in which no stamp is held as viewed from below, and (b) shows a cross-sectional view of an example in which the suction part has a reduced pressure space. 1A and 1B are diagrams illustrating the operation of a pickup device that constitutes a chip transfer device, showing (a) a state in which the stamp is approaching a chip component on a transfer source substrate, (b) a state in which the stamp is in close contact with the chip component, and (c) a state in which the stamp has picked up a chip component from the transfer source substrate. This explains the operation of the mounting device that constitutes the chip transfer device, and shows (a) a state in which a stamp holding a chip component is approaching a destination substrate, (b) a state in which the chip component is in close contact with the destination substrate, and (c) a state in which the stamp moves away after mounting the chip component on the destination substrate. 1A and 1B are diagrams illustrating the state of the stamp, showing (a) the stamp after the pick-up operation, (b) the stamp after the mounting operation, and (c) the stamp before the pick-up operation and before the mounting operation. 10A and 10B are cross-sectional views illustrating a defect phenomenon that occurs in a stamp, in which FIG. 10A shows a state in which a pick-up operation is incomplete, and FIG. 10B shows a state in which a mounting operation is incomplete. 10A and 10B are diagrams illustrating stamp inspection after a pick-up operation and after a mounting operation. FIG. 1 is a diagram showing a configuration of an apparatus for performing an appearance inspection by irradiating light onto the surface of a stamp. 1A and 1B are diagrams showing an example of an image of the stamp surface after picking up, obtained by irradiating the stamp surface with light, and an example of an image of the stamp surface after mounting, respectively.

Embodiments of the present invention will be described using the drawings. Figure 1 is a cross-sectional view of stamp holding means 1 in an embodiment of the present invention holding a stamp 2. Figure 2 is a schematic diagram illustrating the shape of stamp holding means 2, with Figure 2(a) being a view from diagonally above, Figure 2(b) being a view from diagonally below showing the state when not holding stamp 2, Figure 2(c) being the state before holding stamp 2, and Figure 2(d) being the state when the stamp is held by suction. Note that connecting portion 31 connects a drive mechanism (not shown) to stamp holding means 1, and is not limited to the shape shown in Figures 1 and 2; the drive mechanism (via connecting portion 31) can cause stamp holding means 1 to move up and down and horizontally.

In this embodiment, the stamp body 20 and adhesive portion 21 that make up the stamp 2 are made of a translucent material; for example, the stamp body 20 is made of glass, quartz, or translucent ceramics, and the adhesive portion 21 is made of silicone resin.

The stamp holding means 1 holds the stamp 2 from the side opposite the surface on which the adhesive portion 21 is formed, and functions to irradiate the stamp 2 with light. An example of this is the embodiment shown in Figure 1.

The stamp holding means 1 of the embodiment shown in FIG. 1 is configured by stacking an adsorption section 11 and an illumination section 12. The adsorption section 11 adsorbs the stamp 2 from the side opposite to the side where the adhesive section 21 of the stamp body 20 is formed. Adsorption holes 11H are formed on the surface that contacts the stamp 2, and the adsorption holes 11H are connected to exhaust holes 11V. The stamp 2 can be adsorbed by connecting a pressure reducing means (not shown) to the exhaust holes 11V. The adsorption section 11 is also translucent so that light emitted from the illumination section 12 can be irradiated onto the stamp 2. The illumination section 12 irradiates the stamp 2 with light through the adsorption section 11, but it is preferable that the light be irradiated evenly over the entire surface of the stamp 2, and is preferably a planar light source. The planar light source referred to here is not limited to a surface light emitter, but also includes a combination of an LED and a diffuser, such as that used in the backlights of LCD televisions.
The suction unit 11 may be configured to have many flow paths from the suction holes 11H to the exhaust holes 11V in a transparent plate-like material, but this requires time and effort to process and the flow paths provided in the transparent material scatter light. Therefore, if the flow paths are not evenly provided on the front surface, the in-plane distribution of light within the suction unit 11 may change, resulting in a bias in the distribution of light irradiated onto the stamp 2, which is not preferable.

For this reason, it is preferable to use the configuration shown in Figure 3 for the suction unit 11. That is, a box is formed by a lower plate 111 made of a translucent plate with suction holes 11H, and upper plate 112 and side plate 113 also made of translucent plates, forming the reduced pressure space 110. This structure can be constructed relatively inexpensively. The material for the lower plate 111 and upper plate 112 can be a transparent resin such as acrylic, but glass is preferable in consideration of shape stability, and frosted glass may also be used as long as it is translucent. Furthermore, in Figure 3, the illumination unit 12 is composed of a light source 121, which is a surface light source, and a light source cover 120, and the light source cover 120 is connected to the suction unit 11.

Figure 4 shows the configuration of a stamp inspection device that uses the stamp holding means 1 of the present invention to inspect the state of chip components attached to the stamp 2. In Figure 4, the camera 4, which is the imaging means, is directed toward the chip component holding surface of the stamp 2, just as in Figure 16, but the image captured by the camera 4 is not an image obtained by light reflected from the chip holding surface of the stamp 2, but an image obtained by light passing through the stamp 2.

With the stamp inspection device shown in Figure 4, light is blocked where chip components C are present, while light is transmitted where chip components C are not attached, resulting in greater contrast depending on whether or not chip components C are present. That is, in the transmission image captured by camera 4, as shown in Figure 5, ITC is dark in the areas corresponding to where chip components C are attached, and IT21 is bright in the areas corresponding to adhesive portions 21 where no chip components C are attached, with IT21 being the same brightness as IT20, which corresponds to only the stamp body 20.

As a result, as shown in Figure 5(a), when observed after the pick-up operation and before mounting, there is a large difference in brightness in areas where no chip components C are attached, and when the image captured by camera 4 is processed using image processing means, the presence of attached chip components C can be clearly seen. Furthermore, as shown in Figure 5(b), the presence of chip components C remaining on stamp 2 can also be clearly seen when observed after the mounting operation.

In some cases, positional information for chip components C on stamp 2 may be required. In such cases, the positional information for each chip component C is obtained using a predetermined position as the reference. For example, the predetermined position may be the positional information of a chip component selected from the four outermost corners. However, as shown in Figure 6, there may be cases where no chip component C is held in the relevant location. In light of this situation, taking the four corners as an example, the positional information for the intersections of several chip components C in the X and Y directions near the four corners may be obtained and used as the reference, as shown in Figure 6.

Note that with regard to the post-mounting operation shown in Figure 5(b), when using a transmitted light image, it is difficult to determine a reference point because the portion IT21 corresponding to the adhesive portion 21 to which no chip component C is attached and the portion IT20 corresponding to only the stamp body 20 have similar brightness, making it difficult to obtain contrast. Furthermore, to obtain positional information for each chip component held on the stamp 2 with even greater precision, as shown in Figure 7, stamp recognition marks AS (first stamp recognition mark AS1, second stamp recognition mark AS2) are used, each having a protruding shape at a predetermined location on the stamp body 20. However, these stamp recognition marks AS are also difficult to recognize in a transmitted light image.

For this reason, when obtaining position information for the portion corresponding to the adhesive portion 21 where no chip component C is attached, or for the stamp recognition mark AS, it may be desirable to obtain a reflected image by turning on the reflection light source 40 with the illumination unit 12 turned off, using an apparatus configuration equipped with a reflection light source 40 as shown in Figure 8.

However, in a configuration in which multiple suction holes 11H are formed in the suction portion 11, such as the lower plate 111 in Figure 3, the suction holes 11H can cause problems. One such problem is that, as shown in Figure 9, when comparing the contrast between the ITC in the portion corresponding to the location where the chip component C is attached, the IT21 in the portion corresponding to the adhesive portion 21 where no chip component C is attached, and the IT20 in the portion corresponding to only the stamp body 20, the IT11H corresponding to the suction hole 11H may be reflected and cause disturbance. Furthermore, if the stamp body 20 is sucked into the suction hole 11 and a dent is formed in the adhesive portion 21, this may interfere with handling of the chip component C held by the adhesive portion 21.

To avoid this phenomenon, as a modified embodiment of the present invention, the stamp 2 may be held by suction on the surface of a porous body, an example of which is shown in Figure 10. Figure 10(a) shows an example in which a porous region 11P is provided instead of the suction holes 11H shown in Figure 2(b). Figure 10(b) shows an example in which a porous region 11P is provided in the lower plate 111 of Figure 3(a) instead of the suction holes 11H.

By holding the stamp 2 by suction in the porous region 11P, problems caused by the suction holes 11H are alleviated. However, if the average pore size of the porous material becomes too large, problems similar to those caused by the suction holes 11H may occur, so it is desirable for the average pore size to be 10 μm or less.

The porous material is not limited to translucent glass or ceramics; non-translucent materials made of metal can also be used as long as they transmit light through the pores (or reflect light from the inner surfaces of the pores). Furthermore, if the light reflectance outside the porous area is high, high contrast may not be obtained when detecting the stamp recognition mark AS using the reflected image shown in Figure 8, making it difficult to obtain accurate position information. For this reason, it is desirable for the appearance of the porous material used in the porous region 11P to be a color darker than white (such as black).
As described above, in the present invention, transmitted light is used, and while light is blocked by chip components C, areas where chip components C are not present are almost uniformly bright, and an image with high contrast is obtained, so there is almost no chance of erroneously determining whether or not chip components C are attached, even when the chip components C are small.

For this reason, by using the stamp inspection device 7 of the present invention to inspect the stamp 2 used in the pickup device 5 and mounting device 6 shown in Figure 15, it is possible to create a chip transfer device with fewer problems.

By the way, if the stamp 2 is switched between the stamp holding means 1 and the pickup head 101 used in the pickup device 5 or the mounting head 102 used in the mounting device 6, the pickup device 5, mounting device 6, and stamp inspection device 7 can each be operated independently, which is preferable as it increases the efficiency of the chip transfer device as a whole.

On the other hand, the function of the stamp holding means 1 of the present invention may be provided by the pickup head 101 or mounting head 102. However, it is difficult to provide both the light-emitting function of the stamp holding means 1 and the heating function of the mounting device 6, but it is relatively easy for the pickup head 101 to provide the stamp holding means 1.

REFERENCE SIGNS LIST 1 stamp holding means 2 stamp 4 camera 5 pickup device 6 mounting device 7 stamp inspection device 11 suction portion 11H suction hole 11P porous region 11V exhaust hole 12 lighting portion 20 stamp body 21 adhesive portion 31 connecting portion 40 reflection light source 101 pickup head 102 mounting head 110 reduced pressure space 111 lower plate 112 upper plate 113 side wall 120 light source cover 121 light source AS1, AS2 stamp recognition mark C chip component S0 transfer source substrate S1 transfer destination substrate

Claims (7)

A stamp inspection device that inspects the state of attachment of chip components to a stamp,
The stamp uses its adhesiveness to simultaneously attach multiple chip components, transferring the chip components on the source substrate to the destination substrate.
a stamp holding means for holding the side opposite to the adhesive surface of the stamp and irradiating the stamp with light ;
and an imaging means for capturing an image transmitted through the stamp while irradiating the stamp with light. The stamp inspection device according to claim 1 ,
The stamp inspection device further comprises image processing means for determining whether or not a chip component is attached to a predetermined location on the stamp from the image acquired by the imaging means. The stamp inspection device according to claim 1,
The stamp holding means
a light-transmitting adsorption portion that adsorbs and holds the opposite side of the stamp's adhesive surface;
a lighting unit disposed on the opposite side of the suction unit from the surface that suctions the stamp, and that irradiates light onto the stamp through the suction unit. The stamp inspection device according to claim 3 ,
The stamp inspection device is characterized in that the suction unit has a lower plate made of a translucent plate with suction holes, an upper plate that is also translucent, and side plates, and is configured so that a reduced pressure space can be formed inside. The stamp inspection device according to claim 3 ,
The stamp inspection device is characterized in that the suction portion has a porous region, and the porous region adheres closely to the stamp and holds it by suction. a pickup device that uses the stamp to simultaneously pick up a plurality of chip components on the transfer source substrate;
a mounting device that uses the stamp to simultaneously mount a plurality of chip components on the destination substrate;
A chip transfer device comprising the stamp inspection device according to claim 1 or 2 . 7. The chip transfer device according to claim 6 ,
a function of inspecting the stamp after the pick-up operation is performed by the pick-up device using the stamp inspection device;
and a stamp inspection device that inspects the stamp after the mounting operation has been performed by the mounting device.