KR940004787B1 - Drying method and apparatus therefore - Google Patents

Abstract

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Description

[Name of invention]

Drying method and apparatus

[Brief Description of Drawings]

1 is a view for explaining the basic drying mechanism of the present invention, the specific number is shown as an example using water as a steam source.

The vertical axis represents (a) the surface temperature of the object to be dried: T (° C.); (b) the amount of water present in the inner space of the storage container of the object: w (mg / ι); (c) a surface water content of the dried object: m (g / ㎡); (d) is the amount of condensate: Q (g); The abscissa indicates the elapsed time: t (subscript 0: when inserted into the storage container of the object; 1: when the steam is introduced into the storage container; 2: when the steam is introduced into the storage container and when cooling of the container is started; 3 : Cooling stop of storage container and start of introduction of dry gas into the container; 4: at the end of drying operation.

In addition, the subscripts of T and W represent each state value of T and W in each test corresponding to that of t, and the subscript of M represents S: before drying, max: maximum, f: sinus, and angular value of Q. I and II show the total amount of condensate during steam introduction and cooling, respectively).

2 is a longitudinal sectional view of one embodiment of the apparatus of the present invention;

3 and 4 are longitudinal cross-sectional views of another embodiment of the device of the present invention, in particular showing the introduction of different vapors (which cover the steam in situ) different from the second degree.

* Explanation of symbols for main parts of the drawings

A: Object to be dried 1: Storage container

2: lid 3: bottom

4: steam introduction pipe 5: trap

6: condensate overflow pipe 7: dry gas introduction pipe

8: cooling unit 9: cooling water inlet tube

10: cooling water discharge pipe 11: dry object support

12: liquid crying tube 13: heater

14 condensate discharge pipe 15 drain pipe

21, 22, 23, 24, 25, 26: valve 33: liquid level detecting means

Detailed description of the invention

[Technical Field]

Industrial Applicability The present invention provides a drying method for removing moisture adhering to the surface of an electronic component such as a printed wiring board, an optical component such as a lens or a prism, and precision cleaning or surface treatment of a precision mechanical component such as a gear or a lead frame. A method and apparatus therefor.

[Background]

Electronic parts such as semiconductors, liquid crystal display devices, printed wiring boards, optical parts such as lenses and prisms, and precision drying of surface parts such as gears and lead frames. It is required to remove the water safely and in a short time, and at the same time, a high dry finish state can be performed by addition.

Usually, the drying method is selected in consideration of the level of drying finish of the object to be dried, efficiency of drying operation, cost, and the like. However, in the drying method conventionally used, none of these requirements is satisfied. Development of new drying methods was expected.

1. Wiping drying method

It is a method of wiping wet surfaces with a dry cloth or sponge and sucking moisture, but it is easy to apply to small and complicated complex objects, and it is hard to say that the finish is good and workability is bad. .

2. Hot air circulation drying method

It is a method of putting dry objects in a container in which airflow is circulated, and they are easy to handle, and they are widely used.However, because hot air directly touches the dry objects, the secondary air is prevented from being contaminated. It is required not to include at all.

However, it is practically impossible to remove it completely, and a high dry finish cannot be expected.

3. Drying method of blowing gas (air, nitrogen gas, etc.)

Although it is a method of blowing air or nitrogen gas to the dry object and drying it, there is a problem in terms of cost because it requires a large amount of high purity gas, and the part which the gas does not reach is hard to dry, There is a drawback that occurs.

4. Infrared, far infrared ray irradiation drying method

By using infrared rays or far-infrared rays as a drying heat source, if the atmosphere (environment) is clean, high drying finish can be expected, but dry stains tend to be prone in a dry object having a slow drying speed and a large and complicated shape.

5. Vacuum drying method

It is a method of putting a dry object in a container and using a vacuum forming device such as a vacuum pump or an aspiretta to depressurize the inside of the container to evaporate and remove water, but as the evaporation of water removes the latent heat of evaporation from the dry object. The temperature of the object to be dried decreases, and as a result, it takes a long time to evaporate (dry) the water.

In addition, in the case of using an aspiretta as the vacuum forming apparatus, a very long time is required until a predetermined decompression condition is formed, and a large amount of water is required as the driving source, while a vacuum pump is used. In order to shorten the formation time of the reduced pressure condition, it is necessary to use a large displacement.

In addition, there is a problem in terms of the initial cost, such as the need for a rehabilitation device for the dried object by oil of the vacuum pump, and since it is a rotating machine, it requires human hands and cost to repair it.

6. Spin-out drying method

The method of blowing water by centrifugal force has the advantage of being able to dry in a very short time, but the drawback that blown water (which is often dirty) flies through the device as a fog and reattaches to the object to be polluted. have.

7. Solvent Steam Drying Method

By drying the hydrophilic solvent vapor into the object to be dried and substituting water and the solvent, it can be seen that drying is very good.

However, since a flammable thing like isopropyl alcohol (IPA) is generally used as a solvent, it is necessary to provide an explosion-proof structure and to provide an extinguishing facility so that it may not be flammable to the vapor | steam.

8. Water substitution drying method

The surface of the surface is removed with a non-flammable hydrophilic agent (water remover), for example, Fron 113 / alcohol or a Fron 113 / surfactant-based solvent, and then finished by removing the digital solvent with a non-flammable organic solvent, for example 113. There is no flammability and can be dried easily, but the surface tends to be slightly hydrophobic (presumed by adsorption of the pron), and the drying finish is not good.

In addition, Fron 113 is said to be a factor of ozone layer destruction, and this method is not preferable because of its use.

[Initiation of invention]

BACKGROUND OF THE INVENTION Field of the Invention [0002] The present invention is conventional in drying after performing fine cleaning or surface treatment of electronic components such as semiconductors, liquid crystal display devices, printed wiring boards, optical components such as lenses and prisms, and precision mechanical components such as gears and lead frames. The present invention provides a method and apparatus that satisfies all of the requirements that cannot be met by the technology, which can safely and shortly remove the surface water of the component and at the same time obtain a high dry finish at low cost.

According to the method of the present invention, by introducing a heated vapor into a storage container, the dried object in the container is heated, the air present in the interior space of the container is replaced by the heated steam, and then the container is sealed. Then, the interior space of the container is cooled, and again, the drying gas is introduced into the container after the cooling operation.

The steam uses steam having a temperature (boiling point) at which the vapor pressure becomes at least a large company (760 mmHg).

As the steam source, water is generally used in consideration of stability. However, when the heat resistance of the object to be dried is limited, hydrophilic organic solvents having a lower boiling ratio than water, for example, metarol, ethanol, and IPA (isopropyl) Lower alcohols such as alcohol), acetone, and the like may be used.

What is used as a hydrophilic organic solvent may be suitably selected considering the chemical resistance of a to-be-dried object and the cost of the solvent again.

In addition, the boiling point of said each steam source is as follows.

We write vapor pressure at 20 degrees Celsius together

Non-combustible gas, for example air or nitrogen gas, is passed through the brakes and dried again.

This operation prevents the reattachment of moisture to the surface of the object to be dried. (The temperature of the object to be dried is reduced from T3 to T₄, but the thermal energy corresponding to the decrease is evaporated to the remaining water in the container. This also serves as a source of latent heat, which contributes to the prevention of reattachment of moisture to the surface of the object to be dried).

5. After the pressure in this container returns to atmospheric pressure, remove the dry object from this container.

6. Repeat the above steps 1-5.

As described above, the method of the present invention first heats the object to be heated as steam (of course, the vapor that has released heat energy condenses on the surface of the object to be heated, so that the moisture attached to the surface of the object to be replaced with condensed water, and finally The condensed water is replaced by the steam when the temperature of the object to be dried is equal to the steam temperature).

The interior space of the container is filled with steam, the container is kept in the outside air, and then the interior space of the object to be cooled is cooled, and the moisture present in the interior space is condensed. Pressure is reduced).

Finally, the method of drying by introducing a drying gas into the interior space by operating the internal space pressure to atmospheric pressure, whereby the cooling part and the object to be dried are placed in a state capable of being heated only through the gas phase; and An important point is to prevent the condensate condensing on the surface of the cooling part from reattaching to the object to be dried.

The apparatus of the present invention heats the dry object in the container while introducing the heated steam into the storage container. After replacing the air present in the container with the heating steam, the container is kept in a sealed state, the container is cooled, and after the cooling operation, dry gas is introduced into the container. An apparatus for drying a dry object, wherein water is introduced into a dry object storage container, and water for cooling the inner space of the storage container and a storage of condensate. And a discharging means, a means for introducing dry gas, and at the same time, the container can thermally insulate the cooling portion of the cooling means and the object to be dried, and can block the interior space of the storage container from the outside air. Characterized in having a.

Here, as the storage container, a user (considering storage and discharging of the condensate), usually having the lid fixed to the upper part (considering taking out and out of the dry object), a cylinder (considering that the drying operation is carried out under reduced pressure conditions temporarily. Use steel containers of type).

Of course, it goes without saying that various pressure vessels can be used.

The steam introduction means usually means a pipe (installing a plate to block flow control and / or inflow) in contact with an off-site steam generating source, but a heater, for example, an electric heater or steam in the container. A heater, etc. may be provided, the liquid previously filled in the storage container may be heated, and steam may be generated in the system.

In the case of using a steam heater, the steam introduction operation and the cooling operation are continuous operations. Therefore, the cooling means (usually the side wall and / or bottom of the storage container have a double wall structure, and a cooling tube is disposed in the interior space of the storage container, The cooling unit of the indirect cooling system which allows the refrigerant to flow from the inside or the outside of the system may be used as the heater (in this case, a valve for converting and introducing the refrigerant and the refrigerant into the device is necessary.).

The cooling section may be arranged at a distance in a horizontal direction from the storage position of the object to be stored in the container so that the liquid condensed on the surface thereof does not come into contact with the object during cooling operation, or a partition is formed between the two. (When placed at approximately the same height as the cooling section and the object to be dried).

Or the cooling part is located below the storage position in the container of a to-be-dried object. In addition, in order to avoid thermal insulation between the object to be dried and the cooling part thereof, the object to be dried is placed directly on or through the support made of a material having a low conductivity material.

Or put it in the container, such as a basket directly from the upper part, and hang it. Storage of that condensate. The discharging means is a space secured to the bottom of the container, and the gun which displays the pipe for discharging the condensate (installing a plate for maintaining the depressurized state of the container) in at least the first degree (d) attached to the deepest part thereof. What is necessary is just to have the capacity | capacitance which can store II of the amount of condensate, or the depth which a liquid level gauge can operate, The shape is preferably conical in consideration of liquid collection property, but it does not need to be limited to it.

In addition, in the case where the steam for heating is covered in the system, the capacity necessary for the prevention of burning of the heater must also be considered.

As a structure that can block the interior space of the container from outside air, a trap that seals the end of the condensate discharge pipe is usually used. (The condensate generated during the steam injection operation is sequentially discharged out of the container via the trap. do).

Means for introducing the dry gas generally mean pipes which connect to the gas source outside the system (installing a plate to block flow control and / or inflow). Since it is a continuous operation, it may be combined with the steam introduction means (in this case, a switching plate between steam and gas is required).

In addition, since the method of the present invention is a batch operation, the apparatus described above is usually prepared in accordance with the line speed of the manufacturing system of the object to be dried, or, on the contrary, the unit time processing capability of the apparatus is increased to increase the short-term. Alternatively, a hydrophobic group may be used.

Best Mode for Carrying Out the Invention

Next, although the detail of this invention is demonstrated referring drawings, it goes without saying that this invention is not limited to this Example.

2 is a longitudinal sectional view showing one embodiment of the drying apparatus of the present invention.

The device is a user cylindrical type with a lid that can hold the object A in it: 1 (bottom: 3 is inverted conical, and lid: 2 can seal the container), one end of which is in the container. Open steam inlet pipe: 4, condensate discharge pipe: 14, trap: 5 connected to the bottom: 3, gas inlet pipe: 7 sections, one end of which is open in the container, coolant inlet pipe: 9 And cooling sections: 8 (with a container side wall having a double wall structure and used as the cooling section) each of which is connected to a cooling water discharge pipe: 10, respectively.

Here, the object to be dried is placed on a lattice support 11 made of a material of low thermal conductivity so as to be thermally insulated from the cooling part.

Each tube: 4, 7, 9, 10, 14 has a plate for adjusting or blocking the flow: 21, 23, 24, 25, 22, respectively.The pressure sensing means: 31 and the temperature sensing means: 32 There are 33 liquid level detecting means.

The drying operation using this apparatus is carried out in the following order (on the drawing, the object to be dried: A is represented as one or a group. The steam is described as water vapor at 100 ° C).

First, put the object to be placed in the container (11, 23, 24, 25: open, 22: closed) in the container (11), and close the lid: 2 (see Fig. 1). The state of t ₀ ) Here, the plate: 21 is opened and water vapor is introduced into the container (time in FIG. ₁ : t ₁ → t ₂ ). Water vapor is obtained by boiling pure water (pure mole) under atmospheric pressure (the source of vapor generation is not shown). The condensate is discharged out of the system via the condensate drain pipe: 14 → trap: 5 → condensate overhaul.

When the temperature of the object and its container becomes the same as the steam temperature, the condensation of the steam ends and the space inside the container is filled with water vapor (see Fig. 1, time: t2. The amount of condensate discharged is constant or "zero," and some steam itself can be used to identify the center of gravity and can be identified by means of temperature detection: 32).

Thereafter, the plates 21 and 22 are closed, and the plates 25 and 24 are opened, and the cooling water flows through the root of the cooling water introduction pipe: 9 → cooling unit: 8 → cooling water discharge pipe: 10 (time in FIG. 1: time: t 2 → t₃). ).

By this operation, the water vapor filling the space inside the vessel is condensed on the surface of the cooling section, the pressure in the vessel drops to 0.023 atmospheres (when the cooling set temperature is 20 ° C), and the condensate accumulates at the bottom of the vessel.

The end point (state of time: t ₃ in FIG. 1) is identified by the liquid level detecting means: 33 (the liquid level must be constant), and the temperature detecting means is confirmed by 32 (the temperature in the inner space of the container is constant. After the plates: 24, 25 are closed and cooling is stopped, the plates: 23 are opened, and the purified gas is introduced into the vessel from the dry gas introduction tube: 7 and the pressure in the vessel is atmospheric pressure (pressure detecting means: Turn the monitor to 31), and open the plate: 22 (discharge condensate accumulated in the bottom of the container out of the system), close the plate: 23, and open the lid: 2 to remove the object to be dried.

This completes the drying operation and prepares for the next drying operation.

In addition, as the discharge means of the condensate (a combined means for blocking the inner space of the vessel and the outside air), the combination system of the plate 22 and the trap 5 is indicated, but the apparatus of the present invention is not limited thereto, for example. , Plate 22 may be pressure-regulated plate and trap 5 may be omitted.

In the above, the case where water is used as a steam source will be described. However, when there is a limit in heat resistance, the following hydrophilic low-boiling organic solvents (for example, various lower alcohols), which are sensitive to ignition explosion (in equipment and in each operation), are used. What is necessary is just to use it, and the heating temperature in that case should be made into the boiling point of each alcohol.

What is necessary is just to select the cooling preset temperature in this case suitably from the refrigerant | coolant temperature which can be ensured, and the thermal fall (temperature difference) with the heating temperature.

3 and 4 are longitudinal cross-sectional views of another embodiment of the apparatus of the present invention, and are examples of cases in which the required steam is covered in the system (in addition, the cooling unit: 8 represents the alternative of FIG. Coil-like piping disposed on the inner bottom surface of the vessel bottom side wall (FIG. 3) or on the inner side wall side (FIG. 4) was used).

In the state shown in FIG. 3, the above-described steam introduction pipe: 4 is replaced with a liquid filling pipe 12, and a heater 13 is newly placed on the outer side wall of the bottom of the container, and the liquid filling pipe 12 is filled in advance in the steam introduction process. By heating a predetermined amount of liquid filled in the bottom of the container via a heater: 13, the heating steam is obtained.

The condensate generated at the time of heating is discharged out of the system via the condensate discharge pipe 14 (plate: 22 is a blocking plate) at the pressure of the heating steam.

In addition, the pipe: 15 is a drain pipe for discharging the condensate (total condensed liquid amount II in FIG. 1 (d)) generated in the cooling step.

Here, the condensate discharge pipe 14 may be used as a liquid filling pipe and a condensate discharge pipe by installing a separate conversion plate.

The aspect shown in FIG. 4 mixes the drain tube 15 and the condensate discharge tube 14 of the aspect shown in FIG. 3, and simultaneously installs the heater 13 in the inner bottom surface of the container bottom wall (even in the apparatus of FIG. The method of generating steam is the same as that shown in FIG.

However, the valve 22 may be a pressure regulating valve, or may be provided with a blocking plate in the same manner as the apparatus of FIG. 2, and a trap 5 may be provided.

In both embodiments, the initial filling capacity can be secured by adding the heat capacity required to be heated by steam and the amount of anti-burning liquid of the heater to the liquid volume obtained from the latent heat of evaporation.

Using the device shown in FIG. Advantageous 10 sheets of was placed in a Pouriescher varnish and dried.

The time required at that time is It was 14 minutes, and the finishing state of the drying was extremely good, without any surface unevenness or adhesions.

In addition, steam used water of 100 degreeC, and dry gas used nitrogen gas, respectively.

[Industry availability]

As described above, according to the present invention, an electronic product such as a semiconductor, a liquid crystal display device, a printed wiring board, an optical part such as a lens or a prism, and a precision cleaning or surface treatment of a precision machine part such as a gear or a lead frame In drying, since a high drying finish state is obtained safely and in a short time, it is extremely useful industrially.

Moreover, this invention has the following advantages which cannot be acquired by the prior art.

1) The use of purified steam and gas, and because they are used once, can achieve particularly excellent dry finish.

2) There is no restriction on the size and shape of the object to be dried, and even a complicated form can be obtained in a highly dry finish state.

3) There is no automatic part inside, and it is simple structure, so there is little trouble, and it is easy to automate the operation.

In addition, the object to be dried is not re-glazed and some washing effect can be expected.

4) The amount of consumables used for drying is small and can be dried with low cost.

Claims (8)

By introducing heated steam into the storage container, the dried object in the container is heated, and the air present in the interior space of the container is replaced with the heated steam, and then the container is sealed, and again after the cooling operation. And drying gas is introduced into the container. The method according to claim 1, wherein the steam is water or a hydrophilic organic solvent having a temperature at which the vapor pressure becomes at least atmospheric pressure. An apparatus for drying a dry object, comprising the method described in claim 1, wherein the dry container includes a means for introducing steam into the storage container of the object, a means for cooling the inner space of the storage container, a storage / discharge means for condensate, and drying. At the same time as having a gas introduction means, the container has a structure in which the cooling portion of the cooling means and the object to be dried can be thermally insulated, and the internal space of the storage container can be blocked from external costs. . 6. The apparatus according to claim 5, wherein the storage container is a user cylindrical forced container for fastening a lid that can be sealed. The container according to claim 4, wherein the cooling means is a means for disposing a cooling surface in the inner space of the storage container, and indirectly cooling the space via the cooling surface, and the cooling surface is the container of the object to be dried. A device disposed at a certain distance in the horizontal direction from the inner storage position, or the cooling unit is located below the inner storage position of the container to be dried. The heat insulating structure of the said cooling part and a to-be-built object is hypothesized by the support means and the support means which are made of the material of the low thermal conductivity fixed to the side wall of the said container upper part space. An apparatus for serving as a support for placing an object to be placed or as a basket for storing an object to be dried, which is suspended in the object to be dried and fixed to the lid of the container. 7. The trap according to claim 6, wherein the structure which blocks the inner space of the storage container from outside is sealed with a sealable lid attached to the upper part of the container, and a trap end of the end of the pipe for discharging condensate connected to the bottom of the container, or A device consisting of a valve attached to a condensate discharge pipe. 5. The apparatus according to claim 4, wherein the steam introduction means is a means for heating the liquid previously filled in the bottom space of the container by means of a heater provided at the bottom of the storage container to generate necessary steam.