JPH1032380A - Substrate heating method and substrate heating furnace - Google Patents

Abstract

(57) [Problem] To uniformly heat and cure a paste applied to a substrate surface, and to manufacture a high-quality substrate. SOLUTION: A substrate 12 coated with a sealant is carried into a furnace, mounted on elevating pins 15 (FIG. 5 (a)), the substrate 12 is lowered to a position near a hot plate 16, and the heated hot plate 16 is heated. Performs the first preheating in FIG.
(B)) Then, the substrate 12 is vacuum-adsorbed to the hot plate 16 and heated by the second preheating (FIG. 5).
(C)) and suction release for stopping the vacuum suction (FIG. 5).
(D)) is repeated a predetermined number of times. As a result, the warpage of the substrate 12 due to the thermal stress caused by the heating is eliminated, and the substrate 1 as shown in FIG.
A state is obtained in which the entire surface of 2 is in close contact with the hot plate.
Therefore, the main heating is performed in a state where the substrate 12 is adsorbed,
Thereafter, it is cooled and carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for heating a substrate in a process of manufacturing a substrate for a display panel such as a liquid crystal display device or a plasma display device, or a printed circuit board.

[0002]

2. Description of the Related Art Recently, liquid crystal panels have been widely used for displays because of their features of being lightweight, thin, and having low power consumption. In a process of manufacturing such a liquid crystal panel, as a means for heating and curing a sealant applied on a glass substrate for a liquid crystal panel, a glass substrate is conventionally placed on a hot plate and sealed at a desired temperature. A hot plate type heating furnace for heating the heating agent is used.

FIG. 8 is a longitudinal sectional view showing a schematic structure of an example of such a conventional substrate heating furnace described in Japanese Patent Application Laid-Open No. 2-83230, and FIG. 9 is a sectional view taken along the line EE in FIG. Numeral 40 is a loading section of the heating furnace, 41 is a furnace body, 42 is a loading section of the heating furnace, 43 is a substrate transfer mechanism, and 44 is a furnace body casing.
45, a motor, 46 a ball screw, 47 a nut,
48 is a linear guide, 49 is a lateral moving mechanism, and 50 is a motor.
51, a ball screw, 52, a nut, 53, a linear guide, 54, a cam, 55, a guide, 56, a vertical movement mechanism,
57 is a substrate moving plate, 58 is a gantry frame, 59 is a substrate,
Numerals 60a to 60c denote a hot plate (hereinafter, when a specific hot plate is represented, the characters are referred to as 60a, 60b, 60c with a lowercase letter added to the end of the code, and when collectively referred to as a hot plate 60), 61 is a pillar, 62 Is an exhaust pipe.

In FIG. 8, a substrate 59 to which a sealant has been applied in a previous step is held by a carry-in section 40 before being carried into a substrate heating furnace. Inside the furnace body 41, hot plates 60a to 60c for mounting and heating the substrate 59 are provided. The substrate 59 having undergone the heat curing treatment of the sealant is transported to the unloading section 42 of the substrate heating furnace, where it is unloaded to the next device.

In the furnace body 41, a substrate transport mechanism 43 for transporting a substrate 59 from the loading section 40 to the unloading section 42 is provided.
Are provided below the hot plate 60, and the hot plate 60 and the substrate transfer mechanism 43 are covered with a furnace case 44. An exhaust pipe 62 for exhausting gas generated inside the furnace case 44 is provided at the ceiling of the furnace case 44.

The hot plate 60 is supported by a column 61, and the furnace case 44 and the column 61 are fixed to a gantry frame 58 at the lower part of the apparatus. The substrate transport mechanism 43 includes a motor 45, a ball screw 46, a nut 47, and a linear guide 48.
A horizontal moving mechanism 49 comprising a motor 50, a ball screw 51, a nut 52, a linear guide 53, a cam 54, a guide 55, etc .;
4 and a substrate moving plate 57 extending from the carry-in portion 40 to the carry-out portion 42.

A horizontal moving mechanism 49 for driving the substrate moving plate 57
Converts the rotation of the motor 45 into a linear movement by means of the ball screw 46 and the nut 47, and drives the substrate moving plate 57 on the linear guide 48 in the horizontal direction in FIG. The distance that the lateral moving mechanism 49 drives the substrate moving plate 57 is determined by the hot play.
G is equal to the center-to-center distance of the points 60a to 60c.

The vertical movement mechanism 56 converts the rotation of the motor 50 into a linear movement by means of the ball screw 51 and the nut 52, and drives the cam 54 on the linear guide 53, so that it is on the cam 54. The guide 55 is driven up and down, whereby the substrate moving plate 57 is driven up and down in FIG.

The motors 45 and 50 each have a built-in encoder and are connected to a controller (not shown). When the motors 45 and 50 rotate in a predetermined direction by a predetermined amount, a signal is sent to the controller. The controller responds to this signal to control the motors 45, 50.
Stop, forward rotation, reverse rotation, etc.

The sealant applied to the substrate 59 has a specific critical temperature at which the curing progresses rapidly and the physical properties change. When the critical temperature is exceeded, the sealant rapidly cures. Therefore, if the temperature and time for heating beyond the critical temperature are not uniform over the entire surface of the substrate 59, the curing of the sealant will be uneven, and properties such as hardness and adhesiveness will be non-uniform, and the substrate 59 will not be uniform.
The quality will be reduced.

Further, when the substrate 59 is rapidly heated, the temperature difference on the surface of the substrate 59 increases until the temperature of the substrate 59 rises and stabilizes, which causes unevenness in the properties of the sealant. In some cases, the stress may be increased to cause breakage. Therefore, the substrate 59 is once preheated at a temperature lower than the critical temperature at which the sealant is hardly cured. Therefore, in general, the temperature of the hot plate 60 is increased step by step in the arrangement order of the hot plates 60 from the loading unit 40 side in order to enable the preheating.

Conventionally, the temperature, time, and the like for performing necessary heating are secured, and the substrate 59 is provided at intervals required by the production line.
In order to supply the hot plate 60, the temperature and quantity of the hot plate 60 are preliminarily increased in a stepwise manner from the loading side, under conditions such as a temperature and a holding time determined by an interval for transporting the substrate 59. The portion to be heated at a desired temperature equal to or higher than the critical temperature is determined according to conditions such as a holding time determined by a holding temperature and an interval at which the substrate 59 is transported.

In the conventional substrate heating furnace shown in FIGS. 8 and 9, the hot plates 60a and 60b are portions for performing preheating, and the temperature is lower than the critical temperature. Further, the hot plate 60c is a portion for heating (main heating) at a desired temperature above the critical point, and the temperature is maintained at the same desired temperature above the critical temperature.

Next, the substrate 5 of the substrate heating furnace having such a structure is used.
The operation for heating and curing the sealant applied to 9 will be described.

First, when the substrate 59 is placed on the carry-in portion 40, the motor 50 rotates to move the cam 54 toward the carry-in portion 40, and at the same time, the guide 55 moves upward to move the substrate moving plate 57. lift. In this process, the substrate moving plate 57 puts the substrate 59 mounted on the loading unit 40 and raises the substrate 59, thereby separating the substrate 59 from the loading unit 40. When the substrate moving plate 57 is lifted to a predetermined height, the motor 5
0 stops and is held at that height.

Next, the motor 45 rotates and the substrate moving plate 5
7 is moved to the unloading section 42 side. Then, the substrate moving plate 5
When the substrate 59 placed on 7 is transported above the hot plate 60a, the motor 45 stops. In this state, the motor 50 rotates in the opposite direction to the above,
4 is moved to the unloading section 42 side, and the substrate moving plate 57 is lowered from the surface of the hot plate 60 and stopped. Thus, the substrate 59 is mounted on the hot plate 60a.

Thereafter, the motor 45 rotates in the direction opposite to the above, and at the same time, the substrate moving plate 57 is
Move to the side. Then, when the substrate moving plate 57 returns to the original position, the motor 45 stops, and one operation ends.

When the first operation is completed, after a lapse of a predetermined time during which preheating is performed, the substrate moving plate 57 repeats the above operation again, and the second operation of moving the substrate 59 from the hot plate 60a to the hot plate 60b is performed. Done
Next, in the third operation, the substrate 59 is placed on the hot plate 60.
b from the hot plate 60c to the hot plate 60c.
To be carried out.

[0019]

However, the conventional heating furnace has the following problems.

Since the upper surface of the substrate 59 is coated with a sealant, the lower surface is supported by the substrate moving plate 57 during transport. Therefore, the hot plate 60
As shown in FIG. 9, is provided to mount a portion of the substrate 59 other than the portion supported by the substrate moving plate 57.

In order to accommodate substrates 59 having different dimensions, substrate moving plates 57 supporting the substrates 59 are provided movably on both sides of the substrate 59 in the feed direction. The width of the substrate 59 in the horizontal direction perpendicular to the feed direction is limited, and as the size of the substrate 59 increases, the area of the portion of the substrate 59 protruding from above the hot plate 60 increases. However, the temperature of the protruding peripheral edge of the substrate 59 is unlikely to rise, and
During the movement of 9, heat is taken by substrate moving plate 57 due to contact with substrate moving plate 57 supporting substrate 59, and the temperature is lowered by moving away from hot plate 60 surface. Since the furnace body case 44 accommodates a plurality of hot plates 60, substrate moving plates 57, and operating parts thereof having different heating temperatures, the furnace body case 44 has a large volume and a large height. Convection occurs throughout 44. The convection is likely to be disturbed by the vertical and horizontal movements of the substrate moving plate 57, whereby the surface temperature of the substrate 59 moving between the hot plates 60 is not constant, and the curing of the sealant becomes uneven.

Further, by repeatedly moving the substrate 59 between the hot plates 60, the substrate 59 and the substrate moving plate 5 are moved.
Since the number of times of contact with the hot plate 7 and the hot plate 60 increases, the amount of dust generated increases. It is desirable that the moving time between the hot plates 60 be short in order to prevent the temperature of the substrate 59 from lowering. However, when the substrate 59 is moved between the hot plates 60 at a high speed, The air flow inside the furnace body 41 is greatly disturbed, and the dust rises, further reducing the cleanliness. In addition, since the driving unit of the substrate moving plate 57 is located inside the furnace case 44, which is the same as the hot plate 60, and the outside air enters by convection, the cleanliness is reduced. From the above, the quality of the substrate 59 is reduced due to the adhesion of the dust to the substrate 59.

Further, in order to ensure the supply of the substrate 59 after the sealing agent is heated and cured by giving a desired heating time to a downstream device connected to the substrate heating furnace, the furnace body 41 is required.
Becomes large, and a large installation area is required. In particular, since the manufacturing apparatus for the substrate 59 is often installed on a clean room, the installation area becomes a problem.

In particular, the hot plate 6 is
When the substrate 59 is mounted on the substrate 59, the lower surface of the substrate 59 is heated.
May be warped. If the heat transfer rate from the lower surface to the upper surface is slow, or if the temperature difference between these two surfaces is large and this temperature difference does not shrink, the substrate 59 remains warped, and the heated and unheated portions And uniform heating cannot be performed. When transferred to the next hotter hot plate 60 as it is, the non-uniform heating is further magnified and the substrate 59 is left without the desired heating.
Could be carried out.

A similar problem can be found in firing of a conductive paste or the like on another display panel substrate or printed circuit board.

An object of the present invention is to provide a substrate heating method capable of solving such a problem, uniformly heating the substrate, and manufacturing a high quality substrate.

It is another object of the present invention to provide a substrate heating furnace having a small installation area, which can uniformly heat the substrate and can produce a high-quality substrate.

[0028]

In order to achieve the above object, a method of heating a substrate according to the present invention comprises mounting a substrate on a heating plate and repeating adsorption and release of the substrate to and from the heating plate. The substrate is heated. The repetition of the suction of the substrate and the release of the suction are performed in a preheating stage before the substrate is continuously suctioned to the heating plate and the main heating is performed.

According to this substrate heating method, when the substrate is heated by repeating the adsorption of the substrate to the heating plate and the release of the adsorption, thermal stress is generated inside the substrate during the adsorption, and the substrate is warped by the release of the adsorption. Become. However, along the part away from the heating plate, the supply of heat from the heating plate decreases during the adsorption release, and the temperature difference between the upper and lower surfaces disappears due to heat conduction,
The warpage gradually disappears. When the substrate is again attracted to the heating plate, stress is generated inside the substrate. However, since the temperature on the upper surface side has increased due to the previous heat conduction, the warpage of the substrate when the adsorption is released again is the same as the previous adsorption. It is smaller than the degree of warpage at the time of release.

Therefore, by repeating the adsorption of the substrate to the heating plate and the release of the adsorption, the warpage of the substrate is gradually reduced, and finally, the warpage of the substrate is almost eliminated.
For this reason, in the main heating stage, even if the adsorption to the heating plate is continued, the substrate can be heated with almost no thermal stress, and a uniformly heated, warped substrate can be obtained. Will be.

Further, the substrate heating furnace according to the present invention has a plurality of small holes penetrating the heating plate, and a plurality of small-diameter rods penetrating the small holes, and a substrate holding member provided so as to protrude above the heating plate. Means, elevating means for elevating and lowering the substrate holding means, adsorbing means for adsorbing the substrate to the heating plate, and controlling the height of the substrate holding means protruding above the heating plate to control preheating,
Means for controlling the temperature to each of the main heating and cooling temperatures, a container including the heating plate and the substrate holding means and having an opening for taking in and out of the shielding substrate and the outside, and a height of the substrate holding means Means for controlling the substrate mounted on the heating plate under control to repeat the adsorption to the heating plate and release the adsorption, and then continue the adsorption to perform the main heating.

According to such a substrate heating furnace, the substrate holding means is provided as a plurality of small-diameter rods penetrating through the inside of the heating plate, so that the area of the heating plate can be increased, and the entire substrate surface can be heated. And the upper and lower surfaces of the substrate can be uniformly heated by heat conduction.

Since preheating, main heating and cooling can be performed only by raising and lowering the substrate with one heating plate, the volume of the container and the total height in the container can be suppressed, and the apparatus can be downsized. In addition, the temperature in the container is made uniform, the temperature difference is eliminated, and convection is less generated, and the heating temperature is stabilized.

Since the substrate holding means has a small contact area with the substrate, the generation of dust due to friction is small, and the mounting of the substrate on the heating plate is performed by mounting the substrate from a preheating position close to the heating plate. The turbulence of the airflow around the heating plate can be reduced, and the convection inside the container is suppressed, so that the dust is not sowed up and a decrease in cleanliness can be prevented.

Further, when the substrate is mounted on the heating plate, the substrate is repeatedly adsorbed and released from the heating plate, whereby the warpage of the substrate can be eliminated, and the substrate is not damaged. It can be heated uniformly.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an appearance of an embodiment of a substrate heating furnace according to the present invention, where 1 is a gantry frame,
2 is a furnace body, 3 is a control unit, 4 is a partition base plate, 5 is a support,
6 is a frame, 8 is a partition, and 9 is an opening.

FIG. 2 is a sectional view taken along the line AA in FIG. 1, wherein 10 is a door (inspection door), 11 is a lifting means, 12 is a substrate, 13 is an exhaust pipe, and 14 is a transfer robot. , FIG.
Are assigned the same reference numerals.

FIG. 3 is a sectional view of a main part taken along the line BB of FIG. 1, wherein 15 is a lifting pin, 16 is a hot plate,
17 is a column, 18 is a heat dissipation prevention cover, 19 is a displacement prevention pin, 20 is a vacuum suction hole, 21 is a vacuum pipe, 22 is a heating heater, 23 is an air supply pipe, 24 is a vertical drive plate, and 25 is a horizontal drive plate. It is a frame, and portions corresponding to the above-mentioned drawings are denoted by the same reference numerals.

FIG. 4 is a cross-sectional view of a main part taken along the line CC of FIG. 2, and portions corresponding to the above-mentioned drawings are denoted by the same reference numerals.

In FIGS. 1 and 2, the substrate heating furnace of this embodiment is installed on the floor by a gantry frame 1 having legs. The gantry frame 1 is a furnace body 2 for heating.
And a space for accommodating a controller 3 serving as control means for the entire heating furnace, such as raising and lowering control of holding means for the substrate 12, control of adsorption of the substrate to a heating plate (hot plate), and temperature control. It is divided into two upper and lower parts with the part II.

In the upper space portion I of the gantry frame 1, two frame sets 6 each composed of a combination of a partition base plate 4 arranged in a horizontal direction and a support 5 arranged vertically to support the partition base plate 4 are arranged in a horizontal direction. And these are arranged in the horizontal direction. In one frame 6, the partition base plate 4 on the ceiling side, the partition base plate 4 on the bottom side, and the partition base plate 4 between them in the upper space portion I are horizontally arranged with each other, and they are located at two locations on both the left and right sides. Each is supported by a support 5. In this one frame 6, two upper and lower spaces are formed, and the furnace body 2 is installed in each of them. Accordingly, in the upper space portion I of the gantry frame 1, two furnace bodies 2 are provided, two on the upper side and two on the lower side.

The portion of the furnace body 2 to be heated is covered with a partition wall 8 in the shape of a container, and the bottom of the partition wall 8 is fixed to the partition base plate 4. As shown in FIG. 2, the partition 8 is provided with an opening 9 for carrying the substrate 12 in and out.
In addition, as shown in FIG. 2, detachable inspection doors 10 are provided on both sides of the container by the partition wall 8. Since the inspection door 10 on one side of the partition 8 is on the outer surface side of the heating furnace, the inspection door 10 can be removed and the furnace body 2 can be maintained.

Here, the substrate 12 is a substrate for a liquid crystal display panel, for example, the substrate is coated with a sealant in a separate process.

An elevating means 11 is provided for each furnace body 2,
Each is fixed to the partition base plate 4. The elevating means 11 has a reciprocating mechanism including a drive motor, a ball screw, and the like (not shown), and its operation is controlled by the control unit 3. As shown in FIG. 3, a vertical drive plate 24 driven vertically by the reciprocating mechanism
The vertical drive plate 24 extends into the furnace body 2.

In the furnace body 2, as shown in FIGS. 3 and 4, a plurality of horizontal frames 25 are connected to a vertical drive plate 24.
The lifting pins 15 are connected to the upper surface of the horizontal frame 25. The elevating pins 15 are rod-shaped with a small diameter, and are holding means for the substrate 12.

Further, a hot plate 16 as a heating plate for contacting and heating the substrate 12 is disposed in the furnace body 2, and the hot plate 16 is connected to the partition base plate 4 via the support pillar 17. Fixed.

Outside the hot plate 16, a heat radiation preventing cover 18 is provided. The heat radiation prevention cover 18 is made of a metal plate such as stainless steel.
Slightly away from it to cover it. As a result, an air layer is formed between the hot plate 16 and the heat dissipation prevention cover 18, and the air layer forms the hot plate 1.
6, the amount of heat radiation is suppressed, and the temperature of the hot plate 16 is stabilized. The hot plate 16 and the heat radiation preventing cover 18 are provided with small holes penetrating them vertically.

The substrate 12 is mounted on a plurality of elevating pins 15 arranged above the hot plate 16. The elevating pins 15 are provided in an appropriate arrangement so as to correspond to the shapes of all the target substrates 12, and their lengths protruding from the hot plate 16 surface are made equal to each other. The positional relationship between the opening 9 provided in the partition 8 and the elevating pins 15 is such that when the substrate 12 is horizontally moved from the opening 9 and carried into the furnace body 2 by the transfer robot 14 shown in FIG. The board 12 is set so that it can be mounted on the elevating pins 15 as it is.

The operating parts in the furnace body 2 are a vertical drive plate 24 and a lifting pin 15 which are raised and lowered by the lifting means 11. The lifting means 11 is arranged outside the furnace body 2, and the substrate 12 extends horizontally from the opening 9. Is carried into the furnace body 2 so that the vertical drive plate 2
It is sufficient if there is a space required for driving the substrate 4 and the driving range of the lifting pins 15 and the space required for carrying in the substrate 12.

On the upper surface of the hot plate 16, the substrate 12
And a plurality of vacuum suction holes 20 arranged at regular intervals. The displacement prevention pin 19 is a rod-shaped member that is detachably fixed to the hot plate 16 by screwing or the like so that the fixing position can be changed according to the shape of the substrate 12, and the substrate 12 is mounted thereon. The portion is provided so as to surround the portion from the periphery, and is positioned, for example, on the four sides of the rectangular substrate 12.

Inside the hot plate 16, a heating heater 22 and a vacuum pipe 21 connected to the vacuum suction hole 20 are provided.
And a vacuum pump (not shown) that is driven and controlled by the control unit 3 is connected to the vacuum pipe 21.

An air supply pipe 23 as an air supply means is provided on the upper side of the opening 9 on the inner side of the furnace body 2. The air supply pipe 23 is a pipe-shaped pipe provided with a number of nozzles directed substantially in the horizontal direction on the side opposite to the opening 9, and allows gas (for example, nitrogen gas) to pass therethrough and pass through the furnace body from these nozzles. Air is supplied into 2.

An exhaust pipe 13 for exhausting dust generated in the furnace body 2 and gas generated by the curing treatment of the sealant is provided on the surface of the partition wall 8 facing the opening 9. I have. In order to increase the internal pressure in the furnace body 2, the air supply pipe 23
The amount of exhaust gas from the exhaust pipe 13 is smaller than the amount of nitrogen gas supplied by the exhaust gas.

As shown in FIG. 2, a transfer head having a shape shown in the figure is provided for loading and unloading the substrate 12 into and out of the furnace body 2 from outside. A transfer robot 14 or the like that operates in conjunction with the above is used.

Next, the operation of this embodiment having the above configuration will be described with reference to FIG. FIG. 5 is a view of the opening 9 side from the dividing line CC of FIG. 2 as in FIG.

First, as shown in FIG.
2 is carried into the furnace body 2 from the opening 9 in the horizontal direction by the carrying-in robot 14 (FIG. 2), and is mounted on the ascending / descending elevating pins 15. At this time, hot plate 16
Is maintained at a desired temperature above the critical temperature at which the sealant applied to the substrate 12 rapidly cures. Since the hot plate 16 is isolated from the outside air by the partition wall 8, its temperature is stable, and the inside of the furnace body 2 is kept at a higher temperature than the outside air temperature by the heat of the hot plate 16.

The air supply pipe 23 always blows out a nitrogen gas at room temperature substantially horizontally from its nozzle in a direction opposite to the opening 9. The nitrogen gas supplied from the nozzle of the air supply pipe 23 has a high degree of cleanliness, and the supply of this nitrogen gas maintains the inside of the furnace body 2 with a high degree of cleanliness. Also,
The exhaust pipe 13 (FIG. 2) constantly exhausts the air in the furnace body 2 and exhausts a small amount of dust generated in the furnace body 2 and a gas generated by heating the sealant.

When the substrate 12 is carried into the furnace body 2, the surface temperature of the substrate 12 rises due to the radiation from the hot plate 16 and the temperature of the inner surface of the partition wall 8. At this time, the interval between the substrate 12 and the hot plate 16 differs depending on conditions such as the temperature of the hot plate 16 and a sealant.

Next, as shown in FIG. 5B, the lifting pins 15 are lowered by the lifting means 11 (FIG. 3), and
2 is held close to the hot plate 16. At this time, the interval between the substrate 12 and the hot plate 16 differs depending on a desired preheating temperature. In this state, the substrate 12 is heated by the radiation of the hot plate 16. Although the temperature of the substrate 12 further rises, the substrate 12 has a hot plate 16
Therefore, the temperature does not rise to the surface temperature of the hot plate 16. Therefore, the substrate 12 and the hot plate 1
By adjusting the distance from the substrate 6, the upper and lower surfaces of the substrate 12 can be preheated to a desired temperature.

An example of the rise of the temperature of the substrate 12 in such a state is as shown in a section I in FIG.

When the temperature of the substrate 12 reaches a desired temperature, the elevating pins 15 are further lowered, and the above-described vacuum pump connected to the vacuum pipe 21 is operated to operate the vacuum suction holes 20.
Inhale from.

Then, by further lowering the elevating pins 15, the substrate 12 is lowered by being surrounded by the displacement prevention pins 19 as shown in FIG. 5C, and is finally placed on the hot plate 16. You. Then, the substrate 12 is vacuum-adsorbed to the hot plate 16 and tightly fixed in order to prevent a gap or a positional shift from occurring during heating due to the operation of the vacuum suction hole 20. In this case, the entire surface of the substrate 12 hardly contacts the hot plate 16 at the same time due to the warpage of the substrate 12 and the working accuracy of the hot plate 16 and the elevating pins 15. For this reason, the substrate 12 is drawn to the vacuum suction port 20 from the portion that first comes in contact with the hot plate 16 and tends to shift from its normal position. Therefore, mechanical deviation from this position is prevented.

The substrate 12 adsorbed on the hot plate 16
Since the lower surface thereof is rapidly heated, the temperature difference between the upper and lower surfaces is large, and thermal stress is generated inside and tends to warp. Therefore, if the suction is continued, the substrate 12 may be damaged, so the suction of the substrate 12 is temporarily released.
As a result, the substrate 12 is released, so that the substrate 12 warps as shown in FIG. However, since heat is not directly applied from the hot plate 16 during the release of the adsorption, the heat received on the lower surface of the substrate 12 is transmitted to the upper surface, and the temperature difference between the upper and lower surfaces is reduced, and the degree of warpage of the substrate 12 is reduced. I do.

After the degree of warpage of the substrate 12 has become sufficiently small in this way, the vacuum pump is again operated to perform vacuum suction on the substrate 12. At this time, the warpage of the substrate 12 is sufficiently small, so that the entire surface of the substrate 12 is adsorbed to the hot plate 16 and a state shown in FIG. In this case, since the temperature difference between the upper and lower surfaces of the substrate 12 is smaller, the thermal stress generated in the substrate 12 is smaller than in the previous case.
The degree of warpage is small.

Hereinafter, the suction and the release of the suction are repeated. As shown in FIG. 7, the suction (ON) and the release of the suction (OF) are performed.
By repeating step F) as appropriate, the degree of warpage of the substrate 12 can be sufficiently reduced.

The repetition period corresponds to the interval I in FIG.
When the warpage is sufficiently reduced, the process proceeds to a period in which the suction is continued, that is, a section III in FIG. here,
In FIG. 6, section I is the first preheating period, and section II is the second preheating period.
Section III is the main heating period.

The entire surface of the substrate 12 is brought into close contact with the hot plate 16, so that a uniform temperature is obtained by heating by heat conduction. Thereby, the sealant applied to the substrate 12 is uniformly heated and cured.

After holding the substrate 12 on the hot plate 16 for a desired time, the suction by the vacuum suction holes 20 is stopped, the lifting pins 15 are raised, and the substrate 12 is raised and lowered again as shown in FIG. Return to the position mounted on the pin 15 and hold it. At this time, the substrate 12 separates from the hot plate 16 and the temperature gradually decreases.

Further, when the substrate 12 separates from the hot plate 16, nitrogen gas blown from the nozzle of the air supply pipe 23 is blown onto the surface of the substrate 12.
2 promotes cooling. The cooling by the nitrogen gas can prevent the hardening of the sealant due to the preheating of the substrate 12. The cooling period of the substrate 12 is a section IV in FIG.

When the temperature of the substrate 12 reaches a desired value and the cooling is completed, the transfer robot 14 (FIG. 2)
2 is carried out of the furnace body 2, and the heat curing of the sealant on the substrate 12 is completed.

In FIG. 6, the adsorption time and adsorption release period of the substrate 12 and the number of repetitions of adsorption and adsorption release in the second preheating period, which is the section II, are based on the thickness, strength, heating temperature, and heat conduction of the substrate 12. It is set arbitrarily according to the rate, the coefficient of thermal expansion and the like. The data for these are stored in advance in the control unit 3 from an input device (not shown) so that a desired heating profile as shown in FIG. 6 is obtained, whereby the above processing is performed by automatic control.

As described above, by preheating the substrate 12 at a position distant from the hot plate 16 and repeating adsorption and release of the substrate 12 to and from the hot plate 16,
Without damaging the substrate 12, preheating is performed at a temperature equal to or lower than the critical temperature, and after the warpage is reduced, the main heating of the substrate 12 is performed.
By adjusting the time for bringing the substrate 12 into close contact with the hot plate 16 and separating the substrate 12 from the hot plate 16 after heating and cooling the substrate 12 to a temperature equal to or lower than the critical temperature, desired characteristics of the sealant can be obtained.

Further, since the surface temperature of the substrate 12 is stabilized and the substrate 12 can be heated at a uniform temperature, the sealant applied to the substrate 12 can be uniformly heated and cured, and a high quality substrate 12 can be obtained. be able to.

Since the driving unit of the furnace body 2 is only the elevating means 11 for raising and lowering the elevating pins 15, the structure is simplified, and the control of the driving unit of the furnace body 2 is only to move the elevating pins 15 up and down. So the control is simplified. Transfer robot 1
Reference numeral 4 denotes a substrate 12 through an opening 9 provided on the front surface of the partition 8.
Is loaded, mounted on the elevating pins 15, and the substrate 12 on the elevating pins 15 is unloaded at the same position after the heating is completed.
Easy to control.

In the furnace body 2, a vertical drive plate 2
The low-temperature outside air enters from the part where the partition wall 8 is notched into the ascending / descending area of 4, and moves along the hot plate 16 to generate an airflow flowing out of the opening 9. However, the nozzle of the air supply pipe 23 is opened. By being provided in a substantially horizontal direction on the opposite side to 9, the airflow toward the opening 9 is canceled.

Since the internal pressure in the furnace body 2 is slightly increased by the nitrogen gas supplied from the air supply pipe 23,
The airflow that tries to enter from outside is canceled out. Since the volume surrounded by the partition 8 can be suppressed, the space around the hot plate 16 is small,
With the heat of 6, the temperature inside the furnace body 2 is easily made uniform, the temperature difference between the upper part and the lower part inside the furnace body 2 becomes small, and the amount of convection generated can be suppressed. Since the convection is not disturbed by the movement of the substrate 12, the heating temperature of the hot plate 16 is made uniform,
The sealant applied to 2 can be uniformly heated and cured.

The gas supplied from the air supply pipe 23 is nitrogen gas, which is an inert gas, and the invasion of outside air is suppressed. Therefore, the concentration of nitrogen gas in the furnace body 2 increases, and oxidation of the sealant can be prevented. .

Although the nozzle direction of the air supply pipe 23 is provided substantially in the horizontal direction on the opposite side to the opening 9, the nozzle direction and the amount of air supply of the air supply pipe 23 depend on the position of the opening 9 of the partition wall 8 and the hot plate. The optimal nozzle direction and air supply amount of the air supply pipe 23 can be changed by the direction and flow rate of convection generated by the position and temperature of the nozzle 16. As an example, when the total height of the partition walls 8 is low and convection inside is suppressed,
It is also possible to form an air curtain by generating an airflow flowing along the opening 9 of the above to suppress the invasion of outside air.

In this embodiment, the number of the furnace bodies 2 is four. The appropriate number of the furnace bodies 2 is a value obtained by dividing the total time of the time when the substrates 12 are present in the furnace body 2 and the time for loading and unloading the substrates 12 into and from the furnace body 2 by the desired substrate 12 supply time. Become. Substrates 12 are sequentially placed in each furnace body 2 at regular intervals.
And the substrate 12 which has been subjected to the heat curing treatment of the sealant.
Are sequentially taken out, the substrate 12 having completed the heat curing step of the sealant can be supplied to the next-stage apparatus at a constant interval. Therefore, by providing the plurality of furnace bodies 2, an interval for supplying the substrate 12 to the next-stage apparatus or the like can be secured.

Further, even if one of the plurality of furnaces 2 fails, the temperature of each furnace 2 can be individually controlled, so that the furnace 2 can be operated without the failed furnace 2 and the manufacturing can be performed. Maintenance can be performed without stopping the line.

Since the inspection door 10 (FIGS. 2 and 4) for performing maintenance and inspection is provided on a side surface perpendicular to the surface into which the substrate 12 is carried, the inspection door 10 on one side is opened for maintenance and inspection. Does not hinder the loading of the substrate 12 into the furnace body 2 except for maintenance and inspection, and does not stop the entire heating furnace.

Further, in this embodiment, the furnace body 2 is arranged in two stages vertically and two rows horizontally, but the arrangement of the furnace body 2 is changed by a combination with a transfer robot 14 for transferring the substrate 12 and the like. You may. The furnace body 2 may be arranged only in the vertical direction, or may be arranged only in the horizontal direction. The arrangement of the furnace body 2 can be appropriately selected depending on conditions such as the floor area and the height of the room in which the furnace body is installed, the number of furnace bodies, the transfer range of the transfer robot 14, and the like. Since the total height of the furnace body 2 is low, even if the furnace bodies 2 are stacked in a plurality of stages in the vertical direction, the installation area can be reduced without increasing the overall size.

Further, in this embodiment, the invasion of outside air into the furnace body 2 is suppressed by suppressing the convection, the cleanliness is increased, and the adhesion of dust to the substrate 12 is prevented. Also, substrate 1
2 is mounted from a preheating position very close to the hot plate 16, the turbulence of the air flow around the hot plate 16 is small, the dust is not sowed up, and the cleanliness can be maintained.

Further, since the contact area between the substrate 12 and the lifting pins 15 is small, the generation of dust due to the friction between the substrate 12 and the lifting pins 15 is suppressed. Since the convection inside the furnace body 2 is suppressed, the generated dust hardly moves upward, and the cleanliness of the substrate 12 can be maintained. Further, since the lifting / lowering means 11, which is a driving portion, is outside the partition 8, the amount of dust generated inside is small, and furthermore, the generated dust is exhausted by the exhaust pipe 13, so that the internal cleanliness can be kept good. As a result, it is possible to obtain a high-quality substrate 12 with less dust.

Further, in this embodiment, suction and release of the substrate 12 on the hot plate 16 are performed by turning on and off the vacuum pump. However, a vacuum source is provided, and a vacuum source is provided between the vacuum source and the vacuum pipe 21. An electromagnetic valve may be provided, and suction and release of the substrate 12 may be performed by turning on and off the electromagnetic valve.

Further, a pressure regulating valve capable of controlling the degree of vacuum is provided between these vacuum sources and the vacuum pipe 21, and a state in which the pressure regulating valve is controlled to a degree of vacuum capable of adsorbing the substrate 12, By switching between a state in which the degree of vacuum is smaller than the warping force of the hot plate 16 and a state where the degree of vacuum is controlled so that the warped portion can be separated from the hot plate 16,
Can be made to be adsorbed and released.

Further, the degree of vacuum of the pressure regulating valve may be maintained constant, and the degree of vacuum may be set to a degree of vacuum at which an attraction force slightly smaller than the warping force of the substrate 12 is obtained. In this case, if the substrate 12 is not warped, the substrate 12
Although the entire surface is adsorbed to the hot plate 16, if a warp occurs due to heating, a warped portion that exceeds the adsorbing force is separated from the hot plate 16, and a state equivalent to the release of the adsorption is obtained.
Then, when the temperature difference between the upper surface and the lower surface is reduced due to heat conduction at a portion distant from the hot plate 16 and the warp is almost eliminated, the entire surface of the hot plate 16 is again formed.
, And becomes in an adsorption state. The adsorption and the release of the adsorption are repeated, and thereafter, the main heating is performed in a state where the adsorption is continued, so that the substrate 12 which is entirely uniformly heated is obtained. This method is effective when the manufacturing accuracy of the substrate 12 is high and the variation is small.
The control of the pressure regulating valve becomes simpler, and the load on the control unit 3 is greatly reduced.

In the above embodiments, a substrate for a liquid crystal display panel was described as an example. However, the present invention is not limited to this, and a substrate such as a substrate for a plasma display panel or a printed substrate may be used. Needless to say, the present invention can be applied to firing of a conductive paste.

[0089]

As described above, according to the present invention,
The substrate can be uniformly heated without being damaged, a high-quality substrate can be manufactured, and the installation area of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is an external front view showing an embodiment of a substrate heating furnace according to the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

FIG. 4 is a sectional view taken along the section line CC of FIG. 2;

FIG. 5 is an explanatory diagram of a substrate heating method using the substrate heating furnace shown in FIG.

FIG. 6 is a diagram showing a temperature change of a substrate in the substrate heating method shown in FIG.

FIG. 7 is a diagram showing a change in a warped state of the substrate due to repetition of substrate suction and release of the substrate in the substrate heating method shown in FIG. 5;

FIG. 8 is a longitudinal sectional view showing an example of a conventional heating furnace.

FIG. 9 is a sectional view taken along the line EE in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stand frame 2 Furnace body 3 Control part 4 Base plate 5 Support 6 Frame 8 Partition wall 9 Opening 10 Inspection door 11 Elevating means 12 Substrate 13 Exhaust pipe 14 Transport robot 15 Elevating pin 16 Hot plate 17 Support 18 Heat dissipation prevention cover DESCRIPTION OF SYMBOLS 19 Position prevention pin 20 Vacuum suction hole 21 Vacuum pipe 22 Heater 23 Air supply pipe 24 Vertical drive plate 25 Horizontal frame

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masayuki Saito 5-2-2 Koyodai, Ryugasaki, Ibaraki Pref. Hitachi Technology Engineering Co., Ltd.

Claims (6)

[Claims] 1. A substrate heating method of mounting a substrate on a heating plate and heating the substrate, wherein the substrate is mounted on the heating plate, and adsorption and release of the adsorption to the heating plate are repeated. A method for heating a substrate, comprising heating. 2. The substrate heating method according to claim 1, wherein the repetition of the attraction of the substrate and the release of the attraction are performed in a preheating step performed before a main heating step of the substrate, which continues to attract the substrate to the heating plate. A method for heating a substrate, comprising: 3. A substrate heating furnace for mounting and heating a substrate on a heating plate, comprising: a plurality of small holes penetrating the heating plate; and a plurality of small diameter rods penetrating the small hole. Substrate holding means provided so as to be able to protrude upward; elevating means for elevating the substrate holding means; an adsorption plate for adsorbing the substrate to the heating plate; and a height of the substrate holding means protruding above the heating plate. Means for controlling the temperature and controlling the temperature to each of preheating, main heating and cooling; and a container including the heating plate and the substrate holding means and having an opening for shielding the outside air and for taking in and out the substrate. By controlling the height of the substrate holding means, the adsorption of the substrate mounted on the heating plate to the heating plate and the adsorption release are repeated, and then the adsorption is continued, and the main heating of the substrate is performed. Means for causing the substrate to be heated. 4. The substrate heating furnace according to claim 3, wherein the means for repeating the adsorption of the substrate to the heating plate and the release of the adsorption controls on / off of a vacuum pump connected to the adsorption means. Substrate heating furnace characterized by the above means. 5. The substrate heating furnace according to claim 3, wherein the means for repeating the adsorption of the substrate to the heating plate and the release of the adsorption are provided between the adsorption means and a vacuum source. A substrate heating furnace, which is a means for controlling ON and OFF of the substrate. 6. A pressure regulating valve according to claim 3, wherein the means for repeating the adsorption of the substrate to the heating plate and the release of the adsorption is provided between the adsorption means and a vacuum source. Wherein the pressure regulating valve is set to a degree of vacuum such that the suction means generates a substrate suction force slightly smaller than a warp force caused by heating the substrate. .