JPH11264668A - Heat equalizer for hot plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a highly accurate temperature distribution while reducing the weight of plate and allowing increase in the size of an object to be heat treated through combination of a honeycomb structure and the thermal performance of a heat pipe. SOLUTION: In order to improve temperature distribution of a hot. plate and to heat treat a work under highly accurate temperature distribution, the heat equalizing plate comprises a plate body 1 and a honeycomb body 2 wherein the plate body 1 comprises a lower plate 11 being heated by a heating body 100 constituting a hot plate, an upper plate 12 mounting a work W, and a side plate 13 and a heat carrier H for heat pipe can be encapsulated. The honeycomb body 2 has multiple cells 21 and bonded, at the opposite ends in the longitudinal direction, to the upper and lower plates 12, 13. The cell 21 has an opening 22 conducting with the heat carrier H, respectively, on the liquid side and steam side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot plate used in a process for performing heat treatment by heating in a production line such as a liquid crystal glass substrate (LCD) or a plasma display panel (PDP) or a production line such as a silicon wafer. Regarding heat bodies.

[0002]

2. Description of the Related Art As a conventional hot plate, a metal plate type sandwiching a cartridge heater or a heater patterned in a plane has been generally used. In such a hot plate, the accuracy of the temperature distribution on the plate surface has been improved by increasing the thickness and weight of the plate in order to increase the heat capacity, or by adjusting the power density on the plate surface.

[0003] However, with such a hot plate, a temperature distribution with a certain degree of accuracy can be obtained on the plate surface itself. However, when a workpiece is placed and subjected to actual heat treatment, the temperature distribution and the heat capacity of the workpiece are not uniform. There has been a problem that the temperature distribution of the plate is affected and the temperature distribution of the plate itself and the work becomes non-uniform.
Further, in recent years, with the increase in size of glass substrates such as LCDs and PDPs, it has become difficult to heat-treat such glass substrates with a good temperature distribution using a conventional hot plate.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and has a good surface temperature distribution.
An object of the present invention is to provide a hot plate soaking plate that can heat-treat a work with an accurate temperature distribution.

[0005]

According to the present invention, in order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a soaking body of a hot plate is provided with a lower plate and a hot plate which are heated by a heating body constituting the hot plate. An external structure formed in a plate shape, which is provided with an upper plate facing the object to be processed by the plate and a peripheral side plate and is enclosed so that a heat medium for a heat pipe can be sealed therein; An internal structure having a lattice-like cross section occupying the inside of the structure, forming a large number of cells, and being joined to the lower plate and the upper plate at both ends in the longitudinal direction of the cells and being adjacent to each other; And an internal structure having openings so as to conduct on each of the liquid side and the vapor side of the heat medium.

[0006]

FIG. 1 shows an example of a schematic structure of a heat equalizing plate which is a heat equalizer to which the present invention is applied. The heat equalizing plate includes a plate body 1 as an external structure, and a honeycomb-shaped honeycomb body 2 as an internal structure having a lattice cross section occupying the inside thereof. The plate body 1 includes a lower plate 11 heated by a heating body 100 constituting a hot plate, an upper plate 12 facing a work W such as an LCD glass substrate which is an object to be processed by the hot plate, and a peripheral side plate 1.
3 is enclosed so that the heat medium H for a heat pipe can be sealed therein, and is formed in a plate shape as a whole. The honeycomb body 2 forms a large number of cells 21, which are joined to the lower plate 11 and the upper plate 12 at both ends in the longitudinal direction of each cell 21, respectively, and the adjacent cells 21 are liquid. An opening 22 is provided so as to conduct on each of the liquid side and the vapor side of the heat medium H inserted up to the surface L.

The plate body 1 varies depending on the size of the work to be heat-treated. For a large-sized work, the plate body 1 is a plate having a size of about 1 m square and a total thickness of about 2 cm. . In FIG. 1A, the thickness of the heat equalizing plate is larger than the actual thickness in order to make the structure easy to understand.

As the upper and lower plates and the side plates 11 to 13, stainless steel plates having a thickness of about 3 mm are usually used. However, the thickness can be further reduced, and other materials can of course be used. Although not shown, the plate body 1 is provided with an appropriate number of ports for injecting a heat medium at appropriate positions. The work W is placed on the upper plate 12 of the plate body 1.
Is supported by a plurality of pins, a hole for penetrating them is formed through the entire body including the honeycomb body 2. At that time, a short tube is adhered to the periphery of the hole by brazing or the like to maintain the pressure-resistant structure. In addition, in the example of FIG. 1, the whole is shown as a square shape, but a round shape or another appropriate shape can be used according to the shape of the work to be heat-treated.

[0009] The honeycomb body 2 has, for example, a thickness of 0.05.
An opening 22 was formed by drilling a thin stainless steel sheet having a thickness of about 0.1 mm through a gear.
To form a corrugated sheet body 23 and assemble them, interpose a brazing material sheet 24 between the joined portions of the cells 21, and integrally join them by firing at a high temperature in a vacuum furnace. Manufactured by The plate body 1 and the upper and lower ends of the honeycomb body 2 are similarly joined by brazing.

The openings 22 of the honeycomb body 2 are vertically open as shown in FIGS. 1 and 2, and separately formed on the liquid side and the vapor side as shown in FIG.
b and an opening 22 opened in the central part in addition to the above.
It may have a shape having c. The opening in the central portion extends over both sides of the liquid level L determined by the amount of the heat medium H to be sealed. Thereby, both the liquid side and the vapor side conduct, the mobility of both is secured, and the liquid level of all cells is also constant. In FIG. 3, the sheet body 23 is shown in a developed state.

As the heating element 100, a normal hot plate having a built-in electric cartridge heater or the like can be used. In this case, since the temperature distribution performance is obtained by the soaking plate, the heating element 100 is not required to have strict temperature distribution performance. Therefore, even a large one can be easily manufactured at low cost. In addition, since the heat medium in the heat equalizing plate has a heat capacity, it is not necessary to increase the heat capacity by increasing the weight and weight of the heating element as in the related art in order to improve the temperature distribution. Therefore, the weight of the heating body can be reduced. The plate body 1 is mounted on such a heating body 100 to be integrated therewith, and receives heat supply therefrom. Therefore, the heater is not embedded, and there is no risk of local heating. In addition, as the temperature control of the plate body 1, a method for controlling the heater output of the heating body 100 by using a sensor for detecting pressure or temperature can be used.

FIG. 4 shows a state of a cross section of an opening in a part of the honeycomb body 2. As shown in FIG. 1, the heating medium H is put into the honeycomb body 2 up to the level L. Water or various commercially available liquids can be used as the heat medium. For example, when the operating temperature of the plate is about 170 ° C. to 300 ° C., by using Dowsum, 3 kgf /
The working pressure can be about cm ² G. Operating temperature is 1
At a relatively low temperature of about 30 ° C, 4 kgf /
It can be used at a pressure of about cm ² G. in this way,
If an appropriate heat medium is selected according to the use conditions of the heat equalizing plate, it is possible to prevent the internal pressure from being extremely high.

When a heating medium is put in the soaking plate and heated by the heating element 100, the heating medium is heated to a target temperature t in the honeycomb body 2 and a part of the heating medium evaporates. The saturated vapor is filled, and the inside of all the cells 21 is equilibrated with the saturated vapor pressure p at that temperature as a whole. In this state, heat is further transmitted from the heating body 100 to the soaking plate, and when the heat medium inside evaporates, the generated steam is removed from the upper plate 1.
The heat of condensation is given to the work W arranged on the upper part of the work W through the work 2 and the temperature is raised. At this time, the pressure inside all the cells 21 of the honeycomb body 2 is always equalized through the openings 22, and the work is heated everywhere by the steam having the same saturation temperature t under a uniform temperature distribution.

When the heat load of the work is non-uniform or fluctuates, the work is heated in a direction to correct it. For the sake of simplicity, assuming that the thermal load on the central cell 21-1 increases as shown in FIG. 4 and its temperature drops by Δt from the surrounding cell 21, as shown in FIG. The pressure also drops by Δp from the surrounding cells 21. At this time, as shown by the arrows, the vapor of the heat medium immediately moves and flows in from the surrounding cells at high speed, and
1-1, the pressure in the upper plate is restored, more steam is supplied to the lower portion of the upper plate of the cell, and the thermal unevenness is corrected by the supply of the latent heat of condensation, so that the temperature distribution of the upper plate itself and the work on the upper plate are corrected. The temperature distribution is modified.

A small amount of steam also flows into the surrounding cells 21 from the surroundings, and the shortage of steam in these cells is compensated. In this case, since the thickness of the upper plate is thin and the sheet 23 of the honeycomb body 1 connecting the upper plate is extremely thin in the form of a film, the heat capacity thereof is small, so that the pressure equalization is prompt. Temperature equalization is achieved. Even when the temperature of a plurality of cells changes, the pressure equalization and the temperature equalization are instantaneously achieved by the inflow of the steam from the cells around the cells.

FIG. 5 shows the forces applied to the upper and lower plates 12 and 11 joined by the sheet 23 of the honeycomb body 2 as described above, and the deformed state thereof. Although the upper and lower plates are continuous on many cells, FIG. 5 shows only one of them. As shown, the internal pressure p acts on the upper and lower plates 12 and 11, and
The circumference is the uniform tension f of the sheet body 23 (F is the resultant force).
And the resultant force of both is P = Ap and F = ftS
Is in a state of being balanced. In this case, the size of the unit cell is determined in relation to the working pressure and the like.
2cm ² , the entire circumference S is 3cm (effective length 2c per cell)
m), t is 0.05 mm, and p is 5 kgf / cm ² , f
= 360 kgf / cm ^2, which is a safe stress that is sufficiently smaller than the allowable stress of stainless steel. That is, even if the sheet body 23 is made sufficiently thin in a thin film shape by the honeycomb cell structure,
The strength which can maintain the internal pressure can be provided.

Next, the upper and lower plates 12 and 11 are replaced with regular hexagonal circumcircles (radius of 5 m) which are considered to be in a stress state relatively close to the regular hexagonal shape of the actual cell.
m), it is assumed that t と な り 0.46 mm from the formula t = d (ZCP) ^1/2 + α stipulated by laws and regulations of the compression vessel. A thickness of t = 3 mm is a very sufficient value. In the above equation, d is the minimum span of 3/8 inch,
Since Z has a shape close to that of a circular plate, it is approximately 1 and C is a constant determined by the mounting state of the flat plate, that is, the supporting state.
5, and α is 0 for stainless steel.
Therefore, the plate body 1 having the upper and lower plates 12 and 11 supported by the honeycomb body 2 has sufficient strength as a pressure vessel having a flat plate structure. As a result, the bending δ of the flat plate, that is, the local distortion is a value that does not matter at all.

Further, since the heat equalizing plate is mounted on the heating plate 100, the bending stress and the bending as a whole do not matter. Further, since no compressive load is basically applied, there is no possibility of buckling even if the thickness of the sheet body 23 is small. However, the upper and lower plates 1
Since the honeycomb members 2 and 11 are integrally connected with the honeycomb body 2 at a certain interval, the second moment of area of the upper and lower plates, that is, the bending rigidity is increased to some extent. Further, since the sheet members 23 are hexagonally connected to each other so as to form honeycomb cells, and the thickness of the plate member 1 as a whole is small, the structure inherently resists compression to some extent. ing. In addition, as described above, the plate 1
Needless to say, since the height of the side plate 13 is low, the side plate 13 has no problem in terms of stress.

As described above, the thickness of the plate body 1 can be reduced, and the thickness of the sheet body 23 of the honeycomb body 2 can be sufficiently reduced. As a result, the heat transfer coefficient to the work is large, the heat capacity is small, the followability to the temperature change is good, and the rapid heating characteristic is good. Therefore, the heat equalizing plate of this example is suitable for a temperature cycle test and the like.

In the above description, the honeycomb-shaped honeycomb body 2 is shown as an example of the internal structure having a lattice cross section. For example, the internal structure having a triangular or square cross section shown in FIG. It is also possible to adopt a body.

[0021]

As described above, according to the present invention, the outer structure is surrounded by the upper and lower plates and the side plates, and the inner structure is provided so as to occupy the outer structure. The outer structure can be rationally reinforced by the inner structure because it is formed and its longitudinal ends are joined to the lower and upper plates of the outer structure. That is, since the upper and lower plates of the external structure are divided and supported by a portion corresponding to the cells of the internal structure to a sufficiently small area, even when the internal pressure is generated, the upper and lower plates are flat and thin. , Its stress and deflection can be made sufficiently small. In addition, since the tensile force due to the internal pressure only needs to be considered as the internal structure, the cell can be made thin and thin. As a result, it is possible to reduce the weight of the inner and outer structures, that is, the entire heat equalizer.

In the soaking body having such an inner and outer structure,
The outer structure is enclosed so that the heat medium for the heat pipe can be enclosed therein, and each of the cells adjacent to each other of the inner structure is opened so as to conduct on each of the liquid side and the vapor side of the heat medium. Therefore, when the heat medium is sealed, the heat medium is at a constant level for all the cells. And since the outer structure is formed so as to be heated from the lower plate by the heater, the inner structure is used to configure one heat pipe as a whole common to all cells and to operate the heater Thereby, an object to be processed, such as an LCD glass substrate, which is arranged to face the upper plate, can be heated.

According to such a heat equalizing body, the heat pipe effect utilizing the latent heat of evaporation of the heat medium has a good temperature distribution and heats an object having a non-uniform heat capacity. Even in this case, the evaporated vapor of the heat medium moves at high speed, and the temperature of the object to be processed can be made uniform. Further, since it is not necessary to embed a heater or the like in the soaking body itself, there is no local heating. Therefore, a heating element composed of a normal hot plate or the like does not require accurate temperature distribution performance. As a result, large-sized products can be manufactured.

Also, since the heat equalizing body forming the heat pipe has an appropriate heat capacity mainly due to the heat medium, the weight of the heating body is increased to improve the temperature distribution like a conventional hot plate. As a result, there is no need to provide a large heat capacity, and it is possible to significantly reduce the weight without affecting the temperature distribution of the soaking body. As described above, since the heat medium composed of the liquid having a large specific heat is used for the weight, the total weight of the apparatus including the soaking element and the heating element can be reduced, for example, in a clean room in which the apparatus is installed. The load-bearing limit of floor grating can be easily satisfied.

Further, since the outer structure having the upper and lower plates as described above is rationally reinforced by the inner structure having a lattice-like cross section such as a honeycomb shape, the thickness of the upper and lower plates serving as direct heat transfer portions is reduced. In addition, the heat transfer coefficient can be improved. as a result,
The rate at which the temperature of the object to be processed is increased or decreased can be increased, and the heat treatment efficiency can be improved. If the internal structure has a triangular or hexagonal cross-sectional shape, the stability against side loads is enhanced, the side surface strength is generated to some extent, and workability and assemblability are improved. Further, such a structure is used as a member of, for example, a rectifying grid or an aircraft, and since there are many commercially available products, the cost of the hot plate soaking body can be reduced.

As described above, in the present invention, by combining the honeycomb structure and the thermal performance of the heat pipe, these synergistic effects are produced, so that the temperature distribution can be made more precise, the weight of the plate can be reduced, and the heat-treatable object can be obtained. Extremely important effects can be obtained as a hot plate for increasing the size.

[Brief description of the drawings]

1A and 1B show a configuration example of a heat equalizing plate to which the present invention is applied, wherein FIG. 1A is a front view including an AA cross section of FIG.
(B) is a plan view including a partial cross section, and (c) is a perspective view showing a partial structure of the honeycomb body.

FIG. 2 is a perspective view showing a state of a part of a process of manufacturing the honeycomb body.

FIGS. 3A and 3B are developed front views showing another example of an opening of a cell.

FIG. 4 is an explanatory diagram of a state of heat transfer between cells.

FIGS. 5A and 5B are explanatory diagrams of forces applied to upper and lower plates of a plate body.

FIGS. 6A and 6B are cross-sectional views each showing another example of a honeycomb-shaped internal structure, showing a part of a position including an opening.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plate body (outer structure) 2 Honeycomb body (inner structure) 11 Lower plate 12 Upper plate 13 Side plate 21 Cell 22 Opening 22a, 22b, 22c Opening 100 Heating body H Heat medium W Work (workpiece)

Claims (1)

[Claims] 1. A heating medium for a heat pipe is provided inside, comprising a lower plate heated by a heating element constituting a hot plate, an upper plate facing a workpiece to be processed by the hot plate, and a peripheral side plate. An outer structure formed in a plate shape and enclosed so as to form a plurality of cells which are formed in a lattice-like cross-section and occupying the inside of the outer structure, and form both ends of the cells in the longitudinal direction. And an internal structure provided with openings so that the respective cells adjacent to each other and joined to the lower plate and the upper plate are connected to each other on the liquid side and the vapor side of the heat medium. Characterized by a hot plate soaking body.