JPH10520A - Base fixing jig and base fixing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve positional accuracy of a base in sucking and improve printing position accuracy by providing a recessed space part which prevents a part of a suction part of a suction pad from being contacted with the main body part of a jig during sucking operation in a region in the circumferential part of a vacuum suction hole. SOLUTION: In a base fixing jig, a recessed space part 15, which prevents at least a part of a suction part 1a of a suction pad 1 from being contacted with the main body part 2 of a jig during sucking operation of the base fixing jig, in a region 14 in the circumferential part of the vacuum suction hole 13 from a base mount face to the inside of the jig main body 2. The presence of the space part 15 permits especially the suction part 1a having the end gradually widened of the suction pad 1 freely deforms in executing sucking operation so as to improve close adhesion between the base 11 and the jig main body 2. When the sucking operation is stopped, simultaneously the suction part 1a of the suction pad 1 can be separated from the base 11 easily and quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for fixing a substrate, and more particularly to a jig for fixing a substrate to a substrate conveyed by a printed board or a film carrier, for example, in a step of performing solder paste printing. And a method for fixing a substrate.

[0002]

2. Description of the Related Art Conventionally, as a method for fixing a substrate in a solder paste printing machine, for example, a vacuum suction method is generally used. In this case, if the adhesion between the substrate fixing jig and the substrate is poor, the vacuum is broken and the substrate cannot be fixed sufficiently. Therefore, in order to improve the adhesion between the fixing jig and the substrate, an example using a fixing jig incorporating a rubber suction cup as disclosed in Japanese Utility Model Laid-Open No. 4-5332 is disclosed. ing.

FIG. 8 shows a specific example of a method of using a fixing jig incorporating such a rubber suction cup. That is, FIG. 8 is a cross-sectional view for explaining a substrate fixing jig of the solder paste printing machine in the above-mentioned conventional example. As shown in the drawing, a jig 2c called a table is attached to the cylindrical portion of the suction pad 1b. A hole 7b corresponding to the shape of the suction pad 1b is opened, and the cylindrical portion of the suction pad 1b is inserted into the hole 7b, and the flared portion of the suction pad 1b comes into contact with the hole formed in the concave shape. At the same time, it is arranged at a position protruding from the surface on which the substrate is mounted.

A first problem with the conventional substrate fixing jig having such a structure is that the suction pad protrudes from the surface on which the substrate is mounted, so that the substrate sandwiches the flared portion of the suction pad. It is fixed in a state, and the flatness of the substrate is deteriorated, the printing surface becomes uneven due to the printing pressure of the squeegee, and the flared portion of the suction pad 1b is dented by the printing pressure of the squeegee. There was a problem that the amount became unstable.

In addition, there is a problem that the substrate is caught on the sticking-out suction pad when the substrate is transported, so that the substrate cannot be transported smoothly. The second problem is that when the substrate is sucked, the suction pad first sticks to the substrate, and then the flared portion attempts to pull down the substrate while deforming, so that the substrate is likely to be displaced. There was a problem.

In particular, when a plurality of substrates conveyed by a film carrier are simultaneously sucked, there has been a problem that positional accuracy between the substrates is deteriorated. Further, as a third problem, since the flared portion of the suction pad is in direct contact with the vacuum suction hole, the suction pad is not easily deformed, and a vacuum leak occurs on a substrate having large irregularities. There was a problem.

In general, when printing solder paste with high precision, a contact method in which a metal mask and a substrate are brought into close contact with each other and printed is used. In such a method, if a vacuum leak occurs when the substrate is adsorbed to the fixing jig, the metal mask is also adsorbed when the metal mask and the substrate are brought into close contact with each other, and the substrate after squeezing is removed from the metal mask. The operation of separating the plate from the metal mask becomes unstable, and there is a problem in that printing defects such as the solder paste remaining in the openings of the metal mask occur.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above-mentioned disadvantages of the prior art and to improve the flatness of a surface coated with a predetermined material, including a printed surface, thereby to print a solder paste. Stabilizes the amount of the substrate or the amount of other specified material attached, improves the positional accuracy of the substrate during suction, and firmly fixes the substrate so that it is not affected by external forces such as the printing pressure of the squeegee. The purpose of the present invention is to improve the accuracy of the printing position or the accuracy of the application position and the adhesion position of a predetermined material.

Another object of the present invention is to improve the adhesion between the substrate and the fixing jig to eliminate the occurrence of vacuum leakage, to stabilize the separating operation, and to determine the amount of solder paste to be printed. The purpose of the present invention is to stabilize the amount of the predetermined material attached. Further, another object of the present invention is to form a suction pad from a conductive material, thereby grounding a substrate, a fixing jig, a printing machine or other processing machines, and thereby forming a semiconductor component which is weak against static electricity. The purpose is to protect.

[0010]

The present invention basically employs the following technical configuration in order to achieve the above object. That is, a substrate fixing jig for fixing a substrate to a jig using a vacuum suction method, wherein a vacuum suction hole provided on a substrate mounting surface of the jig has a cylindrical portion having a vent hole, The suction pad has a structure in which the cylindrical portion of the suction pad is integrally inserted into the suction portion and the cylindrical portion is inserted into the suction pad, and the substrate mounting surface is provided in a region around the vacuum suction hole. To the inside of the jig main body, at least a part of the suction portion of the suction pad does not come into contact with the main body of the jig during execution of the suction operation of the substrate fixing jig. This is a substrate fixing jig provided with the above space portion.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A substrate fixing jig according to the present invention comprises:
Since the above-described technical configuration is employed, the distal end peripheral portion of the suction portion of the suction pad is disposed at a position lower than the substrate mounting surface of the jig, and the distal end peripheral portion does not protrude from the substrate mounting surface. With this configuration, when the suction operation is performed, the substrate is initially weakly attracted to the substrate mounting surface, and then the flared portion forming the suction portion of the suction pad has the concave shape described above. Since the substrate is deformed in the space and is strongly attached to the substrate, the substrate can be firmly fixed to the substrate mounting surface by the vacuum force.

Further, in the present invention, since the substrate comes into contact with the substrate mounting surface first, there is no displacement at the time of suction. Further, since the substrate and the substrate mounting surface are in direct contact with each other, a frictional force is generated, and the substrate does not move due to an external force such as a printing pressure of a squeegee. And the accuracy of the adhesion or application position of other materials is improved.

Further, in the present invention, when the suction operation is stopped, the flared portion returns to the original shape due to the elasticity of the suction pad, so that the suction pad does not catch on the substrate and the substrate is not caught on the substrate. Transport can be performed smoothly. On the other hand, by forming the suction pad according to the present invention from a conductive material, the substrate, the fixing jig, the printing machine or other coating or adhering device can be grounded, and semiconductor components and the like that are susceptible to static electricity can be grounded. It can protect against electrostatic damage.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a substrate fixing jig and a substrate fixing method according to the present invention will be described in detail with reference to the drawings. 1 and 2 are perspective views schematically showing the structure of a first specific example of the substrate fixing jig according to the present invention. In the drawing, the substrate 11 is attached to the jig 2 using a vacuum suction method. A substrate fixing jig 20 for fixing, the substrate mounting surface 12 of the jig 20
Of the suction pad 1 having a cylindrical portion 1b having a ventilation hole 1c and a suction portion 1a having a divergent shape integrally joined to the cylindrical portion 1b. The substrate mounting surface 1 has a structure in which the shape 1c is inserted, and is provided in a region 14 around the vacuum suction hole 13.
2 to the inside of the jig main body 2, the suction pad 1
At least a part of the suction portion 1a of the substrate fixing jig 20
2 shows a substrate fixing jig 20 provided with a concave space 15 so as not to contact the main body 2 of the jig during the suction operation of FIG.

A first specific example of the substrate fixing jig 20 according to the present invention employs the above-described configuration, and a single chip such as a glass epoxy substrate or a ceramic substrate is mounted on the substrate 11. Then, after vacuum fixation, printing of a solder paste or the like or application or attachment of a substance made of a predetermined material is performed on one surface of the chip. A chamber 6 having a vacuum suction port 8 connected to a vacuum source is connected to the jig main body 2 of the substrate fixing jig 20 as shown in FIG. The plurality of vacuum suction holes 13 are opened, and the substrate 11 and the like are sucked to the jig 20.

Although the number of the vacuum suction holes 13 in the present invention is not particularly limited, it can be appropriately determined according to the size and material of the substrate 11 used. Further, in the substrate fixing jig 20 of the present invention, an appropriate depth is provided in the area 14 around the vacuum suction hole 13 from the substrate mounting surface 12 toward the inside of the jig main body 2. It is characterized in that a recessed space portion 15 called a counterbore portion is provided, and the presence of the space portion 15 causes the suction pad 1 to have a particularly flared shape as described later. The suction unit 1a can be freely deformed during the execution of the suction processing operation to improve the adhesion between the substrate 11 and the jig 2 and, at the same time, easily and rapidly when the suction processing operation is stopped. The suction portion 1a of the suction pad 1 can be separated from the substrate 11.

The cylindrical portion 1b of the suction pad 1 is fitted and fixed to each of the vacuum suction holes 13 in the present invention. The shape of the cylindrical portion 1b has a ventilation hole 1c inside, and the outer shape thereof is not particularly limited, but is preferably cylindrical in consideration of workability. It is desirable that the inner surface shape is also cylindrical.

Further, the shape of the suction portion 1a having a flared shape of the suction pad 1 is not particularly limited, but preferably has a conical shape. For example, it may have a cross-sectional shape as shown in FIG.
It is also desirable that it is designed so as to be curved and become gradually thinner from the joint portion with the cylindrical portion 1b to the peripheral edge portion as shown in FIG.

Although the material of the suction pad 1 is not particularly specified, the suction portion 1a having the flared shape is particularly preferable.
Is preferably made of a material having flexibility, being easily deformed, and capable of easily returning to the original state from the deformed state. Further, it is desirable that the suction pad 1 is made of a rubber-like resin in particular, and it is further made of a conductive material obtained by mixing a conductive substance such as carbon into the resin. Is also preferred.

Although the planar shape of the recessed space 15 in the present invention is not particularly specified, it may be made similar to the planar shape of the suction pad 1 from the detection of suction efficiency, workability, and the like. Desirably, if the planar shape of the suction portion 1a of the suction pad 1 having a particularly flared shape is circular, the planar shape of the concave space portion is also circular, and the flared shape of the suction pad 1 is formed. Is desirably formed substantially concentrically with the suction portion 1a having the following.

The inner diameter of the concave space 15 is not particularly limited, but the suction portion 1a of the suction pad 1 is not limited.
May be designed so that a free space is formed so that the peripheral portion of the device can be easily moved. On the other hand, the recessed space 15
The depth h1 of the suction pad 1 whose cylindrical portion 1b is inserted and fixed in the vacuum suction hole 13 in a state where the suction process according to the present invention is not performed, as shown in FIG. The recessed space bottom 16 where the outer peripheral edge of the suction portion 1a is located
It is necessary to set the height to be higher than the height h2.

That is, in the present invention, when the suction process is not performed, the peripheral portion of the suction portion 1a of the suction pad 1 is provided on the board mounting surface 12 of the jig main body 2. It does not protrude. That is, in the present invention, the depth h1 of the concave space 15 is such that the upper end edge of the suction portion 1a of the suction pad 1 when the suction pad 1 is inserted and fixed in the vacuum suction hole 13 is fixed. The jig 2 is set to be lower than the substrate mounting surface 12.

If a specific example of the relationship between the suction pad 1 used in the present invention and the concave space 15 is shown, the external dimensions of the suction pad 1 are as follows. 5m
m, the height of the conical portion is 0.5 mm, the height of the cylindrical portion 1b is 4.5 mm, and the outer diameter is 7 mm in the diameter of the conical portion of the suction portion, and the diameter φ of the cylindrical portion 1b. Is 2.5 mm.

A vacuum suction hole 13 for inserting the cylindrical portion 1b of the suction pad 1 is provided.
Is desirably 2.47 mm to 2.49 mm. Further, the diameter φ of the recessed space portion 15 is 8 mm, and the depth h1 is such that the suction portion 1a of the suction pad 1 is fitted.
Counterbore processing is performed at 0.6 mm. Therefore, when the suction pad 1 is pressed into the vacuum suction hole 13, the height difference between the suction portion 1 a having a flared shape of the suction pad 1 and the substrate mounting surface 12 is set to 0.1 mm. The suction portion 1a of the suction pad 1 is set so as to be fitted into the recessed space 15 without protruding from the substrate mounting surface.

Since the interval between the outer peripheral edge of the conical portion of the suction portion 1a of the suction pad 1 and the inner diameter of the counterbore portion 15 is 0.5 mm, the suction portion is constituted when the suction operation is performed. The conical portion 1a is easily deformed.
In the present invention, an example of the operation of the suction pad 1 when performing suction processing on a substrate or the like using the jig 20 will be described with reference to FIG.

That is, FIG. 4A shows a state before the suction operation is performed as described above,
And the suction portion 1a of the suction pad 1 are not in contact with each other. FIG. 4B shows a state immediately after the start of the suction operation.
The suction portion 1a of the suction pad 1 is lifted upward and comes into contact with the back surface of the substrate 11.

Thereafter, the suction operation proceeds, and the suction portion 1a
As a result of increasing the degree of vacuum inside, as shown in FIG. 4C, the suction portion 1a of the suction pad 1 is deformed into a curved shape and comes into contact with the back surface of the substrate 11, whereby the suction pad 1 However, since the substrate 11 is strongly pulled downward, the substrate 11 is strongly fixed and maintained on the substrate mounting surface 12 of the jig 2.

In the present invention, since the substrate 11 and the like are directly pressed against the substrate mounting surface 12 of the metallic jig, the warpage of the substrate is corrected, and This is effective for processing such as printing since the flatness of the image is improved. In this specific example, for example, when a solder paste or the like is printed on one surface of the substrate 11, as shown in FIG. 1 or 2, a frame formed of an appropriate material around the substrate 11. It is also possible to provide the body part 17.

The purpose of the frame portion 17 is, for example, to print solder paste or the like on one surface of the substrate 11 and to reduce the size of the substrate 11 when the size of the substrate 11 is smaller than the length of the squeegee of the printing machine. , Or a part thereof, it is possible to apply a constant printing pressure regardless of the size of the outer diameter of the substrate. In this case, the thickness h <b> 4 of the frame portion 17 depends on the substrate 11 mounted on the substrate mounting surface 12.
It is desirable to set the thickness so as to be smaller than the thickness h3.

With this configuration, when printing, for example, a solder paste or the like on one surface of the substrate 11, it is possible to apply an appropriate printing pressure by squeezing only to the surface to be printed, and to absorb uneven thickness of the substrate 11. As a result, it is possible to perform high-precision printing processing. Next, a second specific example of the substrate fixing jig 20 according to the present invention will be described with reference to FIGS.

The second embodiment according to the present invention shows a configuration in which the first embodiment executes processing such as printing individually on a substrate 11 such as a relatively large LSI. However, in this specific example, a plurality of relatively small LSI
The substrate 11 has a structure suitable for the case where the substrate 11 made of chips and the like is continuously bonded to the belt-like film carrier 9.

That is, as shown in FIG. 7, a process such as printing is performed by fixing a continuous flexible substrate in which chips 11 such as LSIs are serially and continuously bonded to a strip-shaped film carrier 9. It is a jig. In this example, the printing of the solder paste is performed on the upper surface of the film carrier 9 to which the LSI chip 11 is attached.

In this specific example, as shown in FIG. 5, the board is fitted into the jig body and a part of the so-called table 2 in the carrying direction (BB ′) of the board 11 and transported. In this case, the same suction mechanism as that described in the first specific example is disposed on the bottom surface portion 18 of the transfer groove 3. The width of the transfer groove 3 is desirably set to be 0.1 mm wider than the outer diameter measured in a direction perpendicular to the transfer direction of the chip 11 such as an LSI used.

Further, the depth h5 of the transfer groove 3 is set to be about 0.05 mm lower than the thickness h6 of the substrate 11. Therefore, similarly to the first specific example, the printing surface is set to be slightly higher than the surface of the jig main body. By setting such dimensions, the film carrier 9 can be smoothly transported, and at the same time, the same effect as in the first specific example described above is exhibited,
In particular, wrinkles formed on the film surface to which the substrate 11 is not bonded can be absorbed, and when the printing is performed including the wrinkles on the film, the substrate and the film may be separated from each other. In the example, such a problem can be prevented.

In this embodiment, a plurality of vacuum suction holes 13 are formed in one or two to three rows in the inside of the transport groove 3. In FIG.
Are arranged in a line, and the three LSIs inserted into the transport groove 3 are configured to be printed simultaneously. However, the number of the vacuum suction holes 13 arranged in a line is particularly limited. is not.

The dimensions of the suction pad 1, the vacuum suction hole 13 and the concave space 15 in this embodiment are substantially the same as those in the first embodiment. In this embodiment, a continuous belt-like film carrier 9 is mounted on a reel.
Since the film carrier 9 is passed through the substrate fixing jig 20 for use in a two-reel configuration, the separation and engagement with the printing mask 22 are facilitated.
In order to improve the printing efficiency by preventing careless contact with the substrate before printing, it is preferable to provide a tapered portion 4 at at least one of the entrance and the exit of the transport groove 3.

The above-mentioned suction mechanism may be connected to the tapered portion 4. That is, by adopting such a configuration, it is possible to reliably make the escape such that the upper surface of the film carrier 9 carried in and out of the transport groove 3 is lower than the printing execution surface. That is, as a feature of this specific example, the inclined portion 4 is provided at least at one end of the substrate transfer groove 3.

As described above, in the present invention, when the above-mentioned jig is used to fix the substrate to the jig by the vacuum suction method, the jig is provided on the substrate mounting surface of the jig. A substrate fixing device configured to insert the cylindrical portion of a suction pad including a cylindrical portion having a ventilation hole and a conical suction portion integrally joined to the cylindrical portion into the vacuum suction hole. A jig is used, and a concave portion is provided in a region around a vacuum suction hole provided on the substrate mounting surface. At a time when the suction operation of the substrate fixing jig is not performed, the suction pad is not used. The suction portion of the suction pad does not protrude from the substrate mounting surface, and during the suction operation of the substrate fixing jig, the suction portion of the suction pad deforms inside the jig and sucks the substrate. A cure is provided.

[0039]

In the substrate fixing jig according to the present invention,
As a result of employing the above-described configuration, the printing amount of the solder paste or the amount of other application and attachment materials is stabilized, and not only high-quality printing and other processing can be performed, but also the processing position accuracy of the printing processing and the like is improved. . The reason is that, since the peripheral edge of the suction portion formed by the conical portion of the suction pad is located at a position lower than the substrate mounting surface, the substrate directly contacts the substrate mounting surface from the beginning of the suction processing step. Therefore, the accuracy of the height position and the horizontal position of the substrate is improved.

Further, according to the present invention, the transfer of a substrate or the like can be performed quickly and smoothly. The reason for this is that, as described above, a counterbore process is performed so that the peripheral edge of the suction portion constituted by the conical portion of the suction pad can be arranged at a position lower than the substrate mounting surface, and a predetermined recessed space portion is formed. Is provided, the suction portion made of the elastic body is freely deformed in the space at the start of suction and at the end of suction, and is housed therein.

Further, according to the present invention, even a substrate having irregularities can be fixed at an accurate position where suction is easy. The reason is that, as described above, a space is formed around the conical portion so that the conical portion of the suction pad is easily deformed. Further, in the present invention, by improving the flatness of the printed surface, it is possible to stabilize the amount of solder paste or the like printed, and at the same time, it is possible to improve the positional accuracy of the substrate during suction. In addition, the substrate can be firmly fixed so as not to be affected by an external force such as a printing pressure of a squeegee, and the printing position accuracy can be improved.

Further, in the present invention, the adhesion between the substrate and the jig is improved to eliminate the occurrence of vacuum leakage, to stabilize the plate separating operation, and to stabilize the amount of solder paste printed. It is also possible to solve the problem that the solder paste is sucked at the time of vacuum leakage through the through hole of the substrate as in the related art. Furthermore, since the suction pad is made of a conductive material and the substrate, the fixing jig, and the printing machine are grounded together, it is possible to protect a semiconductor component that is particularly susceptible to static electricity.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a specific example of a substrate fixing jig according to the present invention.

FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1 showing a state during execution of a suction operation in a specific example of the substrate fixing jig according to the present invention.

FIG. 3 is a sectional view showing a structural example of a suction pad used in the present invention.

4 (A) to 4 (C) are views for explaining a state of a change of a suction pad in a substrate fixing jig according to the present invention. FIG.

FIG. 5 is a perspective view showing the configuration of another specific example of the substrate fixing jig according to the present invention.

FIG. 6 is a cross-sectional view of another specific example of the substrate fixing jig according to the present invention, taken along line BB ′ in FIG.

FIG. 7 is a view showing a state where a suction operation is being performed in another specific example of the substrate fixing jig according to the present invention;
It is sectional drawing seen from the line.

FIG. 8 is a perspective view showing an example of the configuration of a conventional substrate fixing jig.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Suction pad 1a ... Suction part and cone part which have a flared shape 1b ... Cylindrical part 1c ... Vent hole part 2 ... Jig body and table part 3 ... Conveyance groove 4 ... Taper part 6 ... Chamber part 8 ... Vacuum suction Source 9: Film carrier 11: Substrate, chip 12: Substrate mounting surface 13: Vacuum suction hole 14: Peripheral area of vacuum suction hole 15: Recessed space, counterbore processing portion 16: Recessed space bottom Part 17 Frame part 20 Board fixing jig 22 Mask

Claims (10)

[Claims] 1. A substrate fixing jig for fixing a substrate to a jig using a vacuum suction method, wherein a cylindrical portion having a vent hole is provided in a vacuum suction hole provided in a substrate mounting surface of the jig. A vacuum pad having a structure in which the cylindrical portion of the suction pad including the suction portion formed of the flexible flared portion integrally joined to the cylindrical portion is inserted, and the vacuum In the area around the suction hole, at least a part of the suction portion of the suction pad moves from the substrate mounting surface toward the inside of the jig main body while the suction operation of the substrate fixing jig is being performed. A substrate fixing jig provided with a recessed space so as not to contact the main body of the jig. 2. The depth of the recessed space is such that when the suction pad is inserted and fixed in the vacuum suction hole, the upper edge of the suction portion of the suction pad is higher than the substrate mounting surface of the jig. 2. The substrate fixing jig according to claim 1, wherein the jig is set to be lower. 3. A frame body having a thickness smaller than a thickness of a substrate mounted on the substrate mounting surface is disposed on at least a part of the substrate mounting surface. 3. The substrate fixing jig according to 2. 4. A substrate transfer groove is provided in at least a part of the substrate mounting surface including the vacuum suction hole, and a depth of the substrate transfer groove is set to a thickness of a substrate passing through the substrate transfer groove. 2. The method according to claim 1, wherein the depth is smaller than the depth.
Or the substrate fixing jig according to 2. 5. The substrate fixing jig according to claim 4, wherein an inclined portion is provided on at least a part of an end of said substrate carrying groove. 6. The substrate fixing jig according to claim 1, wherein said suction pad is made of a conductive material. 7. The substrate fixing jig according to claim 6, wherein said conductive material is a conductive rubber. 8. The substrate fixing jig according to claim 4, wherein the substrate is transported by a film carrier. 9. The substrate fixing jig is used in a step of directly or indirectly applying or printing a predetermined material on the back surface of the substrate.
9. The substrate fixing jig according to any one of items 1 to 8. 10. When a substrate is fixed to a jig by using a vacuum suction method, a cylindrical portion having a ventilation hole and a cylindrical portion having a vent hole are integrated with a vacuum suction hole provided on a substrate mounting surface of the jig. Using a substrate fixing jig configured to insert the cylindrical portion of the suction pad, which is composed of a suction portion of a flared portion, which is joined to the end, and a vacuum suction provided on the substrate mounting surface. In the area around the hole, a concave portion is provided, and at the time when the suction operation of the substrate fixing jig is not performed, the suction portion of the suction pad does not protrude from the substrate mounting surface,
A method of fixing a substrate, wherein the suction portion of the suction pad sucks the substrate while deforming inside the jig during the suction operation of the substrate fixing jig.