JP2019202279A - Coating agent feeder and method for manufacturing printed circuit board with moistureproof film - Google Patents

Abstract

To provide a coating agent feeder which can suppress formation of air bubbles when a moistureproof film is formed with a moistureproof coating agent, and a method for manufacturing a printed circuit board with a moistureproof film which includes the same.SOLUTION: A method for manufacturing a printed circuit board with a moistureproof film according to which in order to form the moistureproof film on a surface of the printed circuit board with a moistureproof coating agent W, the following processes are performed: a coating process in which the moistureproof coating agent is coated onto the surface of the printed circuit board by a coating device 1; and a supply process in which the moistureproof coating agent is supplied to the coating device by a coating agent feeder 2. In the supply process, when the interior of a storage tank 21, which accommodates the moistureproof coating agent, is pressurized with air, thereby transferring the moistureproof coating agent, pressurization is released once and oscillating or stirring is performed, and thereafter, pressurization is performed again so as to transfer the moistureproof coating agent, thereby removing dissolved air from the moistureproof coating agent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coating agent supply device and a method for manufacturing a printed circuit board with a moisture-proof coating, and more particularly, a coating agent supply device to which a moisture-proof coating agent is pumped and a moisture-proof coating agent on the surface of the printed circuit board. The present invention relates to a method for manufacturing a printed circuit board with a moisture-proof coating, wherein the printed circuit board with a moisture-proof coating is manufactured by forming a film.

Conventionally, printed circuit boards in which electronic parts such as chip parts are mounted on printed wiring boards are used in various electronic devices.
High density mounting is required for the printed circuit board in order to satisfy the demand for downsizing electronic devices.
Therefore, the printed wiring board has a narrow wiring pitch.
In a printed circuit board using such a narrow pitch printed wiring board, there is a possibility that a short circuit may occur due to a solder bridge or the like.
Such a short circuit can be caused not only by the solder bridge but also by moisture.
For example, if dew condensation occurs on the surface of the printed circuit board due to water vapor that has entered the electronic device, even if water droplets are extremely small, a short circuit may occur.
Further, if moisture enters the inside of the printed circuit board, it may cause migration or the like.

As a countermeasure against such a circuit short circuit due to moisture, a moisture-proof treatment is performed by overcoating a printed circuit board.
Conventional moisture-proof treatment is carried out by a method that forms a moisture-proof film on the surface of a printed circuit board.
For the formation of the moisture-proof coating, a liquid moisture-proof coating agent is used as described in Patent Documents 1 and 2 below, and the moisture-proof coating is applied to the treated surface of the printed circuit board by applying the moisture-proof coating agent. After the wet coating film is formed, the wet coating film is dried to form a moisture-proof coating.

JP 2011-090661 A JP 2013-234256 A

When applying the moisture-proof coating to the surface of the printed circuit board, the moisture-proof coating is transported from the storage tank containing the moisture-proof coating to the supply destination through the piping, and the moisture-proof coating is uniformly applied to the surface of the printed circuit board through nozzles. A method in which the coating agent is sprayed is employed.
By the way, if the moisture-proof film formed as described above is thick to some extent, it is easy to ensure the reliability of the moisture-proof performance.
In consideration of this, it is advantageous that the moisture-proof coating agent has a certain viscosity or more.
However, if a moisture-proof coating is formed with a high-viscosity moisture-proof coating agent, there is a risk that bubbles will be entrained in the wet coating film, causing bubbles to be present in the finally obtained moisture-proof coating, and sufficient moisture-proof performance may not be exhibited. is there.

It is considered that such bubbles can be suppressed by, for example, prescribing a polysiloxane compound having an antifoaming action such as silicone oil or silicone resin, but the cause of the generation of bubbles in the moisture-proof coating is as described above. Other than that can be considered.
However, the cause of the generation of bubbles other than the entrainment of ambient air during coating has not been fully investigated.
Therefore, as a matter of course, the countermeasures are not sufficiently taken.
That is, there is a problem that sufficient measures have not yet been taken with respect to the generation of bubbles when forming a moisture-proof coating with a moisture-proof coating agent.
Therefore, the present invention has an object to solve such a problem.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has adopted a method in which the moisture-proof coating agent is pumped with air, and in the process, the air is dissolved in the moisture-proof coating agent. It has been found that this is a cause of bubbles in the moisture-proof coating.
In addition, as a result of intensive studies on the deaeration method from the moisture-proof coating agent in which air is dissolved, the present inventor has completed the present invention.
Specifically, the present inventor stirs the moisture-proof coating agent or gives vibration to the moisture-proof coating agent rather than performing general vacuum degassing or heat degassing on the moisture-proof coating agent in which air is dissolved. It is possible to remove air more efficiently by performing such physical operation, and there is a possibility that the solute concentration of the moisture-proof coating agent may be changed by volatilization of the solvent in vacuum degassing or heat degassing. It has been found that such a fear can be suppressed by a physical operation such as that described above, and the present invention has been completed.

In order to solve the above problems, the present invention
A storage tank for storing a moisture-proof coating agent for forming a moisture-proof coating on the printed circuit board;
An air supply device for supplying air to the storage tank,
A coating agent supply device in which the moisture-proof coating agent is pumped from the storage tank toward the supply destination of the moisture-proof coating agent by supplying the air from the air supply device to the storage tank,
The storage tank is switchable between a pressurized state in which the inside is pressurized by the air and a pressurized release state in which the pressure is released,
A vibration device that vibrates the moisture-proof coating agent stored in the storage tank in the pressure release state, and agitation that stirs the moisture-proof coating agent stored in the storage tank in the pressure release state A coating agent supply device further comprising at least one of the devices is provided.

In order to solve the above problems, the present invention
A method for producing a printed circuit board with a moisture-proof coating, wherein a moisture-proof coating is formed on the surface of the printed circuit board by a moisture-proof coating agent to produce a printed circuit board with a moisture-proof coating,
An application step of applying the moisture-proof coating agent to the surface of the printed circuit board with a coating apparatus;
A supply step of supplying the moisture-proof coating agent to the coating device with a coating agent supply device,
In the supply step, the coating agent supply device including a storage tank that stores the moisture-proof coating agent and an air supply device that supplies air to the storage tank is used.
The air is supplied to the storage tank by the air supply device, the interior of the storage tank is pressurized by the air, and the moisture-proof coating agent is pumped from the storage tank to the coating device,
The pumping is performed a plurality of times including a first pumping and a second pumping performed after the first pumping,
A deaeration process for releasing the dissolved air from the moisture-proof coating agent stored in the storage tank by releasing the pressurization of the storage tank between the first pumping and the second pumping. Is implemented,
In the degassing treatment, there is provided a method for producing a printed circuit board with a moisture-proof coating in which at least one of vibration to the moisture-proof coating agent and stirring of the moisture-proof coating agent is performed.

  According to the present invention, air dissolved in the moisture-proof coating agent can be efficiently removed from the moisture-proof coating agent, and generation of bubbles in the moisture-proof coating can be suppressed.

The schematic block diagram of moisture-proof processing equipment. The schematic block diagram of a coating apparatus. The schematic block diagram of the coating agent supply apparatus of 1 aspect. The schematic block diagram of the coating agent supply apparatus of another aspect. The figure which showed the mode of the moisture-proof film formed with the moisture-proof coating agent before deaeration processing by the atmospheric pressure standing at normal temperature (immediately after the end of contact with pressurized air) (appearance photograph of a moisture-proof film). The figure which showed the mode of the moisture-proof film formed with the moisture-proof coating agent after performing the deaeration process by the atmospheric pressure standing at normal temperature (appearance photograph of a moisture-proof film). The figure which showed the mode of the moisture-proof film formed with the moisture-proof coating agent before the deaeration process by heating at 40 degreeC (just after completion | finish of contact with pressurized air) (appearance photograph of a moisture-proof film). The figure which showed the mode of the moisture-proof film formed with the moisture-proof coating agent after performing the deaeration process by heating at 40 degreeC (appearance photograph of a moisture-proof film). The figure which showed the mode of the moisture-proof film formed with the moisture-proof coating agent (after completion of contact with pressurized air) before the deaeration process by stirring (appearance photograph of a moisture-proof film). The figure which showed the mode of the moisture-proof film formed with the moisture-proof coating agent after performing the deaeration process by stirring (appearance photograph of a moisture-proof film).

Embodiments of the present invention will be described with specific examples.
First, a moisture-proof treatment facility for producing a printed circuit board with a moisture-proof coating by forming a moisture-proof coating on the printed circuit board will be described.
FIG. 1 shows an outline of the equipment configuration of the moisture-proof treatment equipment 100 in the present embodiment.
As shown in the figure, the moisture-proof treatment facility 100 includes a coating device 1 for forming a moisture-proof coating on a printed circuit board, and a coating agent supply device for supplying a moisture-proof coating agent to the coating device 1. 2 are provided.

As shown also in FIG. 2, the coating apparatus 1 has a stage portion 11 for horizontally supporting the printed circuit board A, and the printed circuit board A horizontally supported by the stage portion 11. And a coating portion 12 for spray-coating the moisture-proof coating agent W from above.
The coating unit 12 includes a nozzle 121 that sprays the moisture-proof coating agent W downward in a band shape.
The coating apparatus 1 is configured so that the moisture-proof coating agent W supplied from the coating agent supply device 2 can be directly supplied to the nozzle 121 and can be quantitatively discharged from the nozzle 121.

The coating unit 12 includes a linear actuator 122 that can move in the X direction when one direction in the horizontal direction is the X direction and the direction orthogonal to the X direction in the horizontal direction is the Y direction. , And a linear actuator 123 that can be moved in the Y direction.
The nozzle 121 is mounted on a holder 124 that is capable of moving in the horizontal direction with respect to the printed circuit board A by combining the two linear actuators 122 and 123.
That is, the coating portion 12 can form a belt-like wet coating film extending in the X direction with respect to the printed circuit board A and can also form a belt-like wet coating film extending in the Y direction. Yes.
In the present embodiment, a moisture-proof coating formed by curing and drying the wet coating is formed on the printed circuit board A to produce a printed circuit board with a moisture-proof coating.

The coating agent supply device 2 is configured to convey the moisture-proof coating agent W using the coating device 1 (more specifically, the nozzle 121) as a supply destination.
As shown in FIG. 3, the coating agent supply device 2 includes a storage tank 21 that stores the moisture-proof coating agent W, and an air supply device that supplies air to the storage tank 21.
The coating agent supply device 2 of the present embodiment includes an air compressor 22 including an accumulator capable of storing pressurized air as the air supply device.
The coating agent supply device 2 of the present embodiment includes an air supply pipe 22a for conveying air from the air compressor 22 to the storage tank 21, and a three-way valve V1 is provided in the air supply pipe 22a. Is provided.

The three-way valve V1 can be switched between a first state in which the air compressor 22 and the storage tank 21 are in communication with each other and a second state in which the storage tank 21 and the external environment (outside air) are in communication. ing.
That is, the three-way valve V1 functions as a relief valve for releasing the pressurization of the storage tank 21 that is supplied with air by the air compressor 22 and is in a pressurized state.
In other words, the coating agent supply device 2 of the present embodiment includes the storage tank 21 that can be switched between a pressurized state in which the inside is pressurized by the air and a pressurized release state in which the pressure is released. ing.

The coating agent supply device 2 of the present embodiment includes a vibration device that vibrates the moisture-proof coating agent W stored in the storage tank 21 in a state where at least the storage tank 21 is in a pressure release state, and At least one of the stirring devices that stir the moisture-proof coating agent W stored in the storage tank 21 in the pressure release state is provided.
Specifically, the coating agent supply device 2 of this embodiment includes the stirring device 23.

  The moisture-proof treatment facility 100 of this embodiment further includes a coating agent supply pipe 24 for conveying the moisture-proof coating agent W from the storage tank 21 of the coating agent supply device 2 to the coating device 1.

The storage tank 21 includes a bottomed cylindrical tank body 211 having an upper opening, and a lid 212 for closing the upper opening of the tank body 211 so as to seal the inside.
The tank body 211 has a bottomed cylindrical shape including a bottom wall portion 2111 and a body trunk portion 2112 that rises in a cylindrical shape from the outer peripheral edge of the bottom wall portion 2111.
The lid body 212 includes a ceiling portion 2121 and a lid body portion 2122 that is formed in a cylindrical shape from the outer peripheral edge of the ceiling portion 2121 and extends downward.
The storage tank 21 is configured to be in a sealed state by bringing the upper end portion of the main body barrel portion 2112 into contact with the lower end portion of the lid barrel portion 2122.

The storage tank 21 is provided with a discharge port 212 a for discharging the moisture-proof coating agent W toward the nozzle 121.
In the present embodiment, the ceiling portion 2121 is provided with the discharge port 212a.
The coating agent supply pipe 24 for conveying the moisture-proof coating agent W toward the nozzle 121 is connected to the discharge port 212a.

The storage tank 21 is provided with an air supply port 212b for introducing air supplied from the air compressor 22 into the internal space.
In the present embodiment, the air supply port 212 b is provided in the ceiling portion 2121.
The air supply pipe 22a is connected to the air supply port 212b.

In the storage tank 21, a coating agent discharge pipe 213 extending in the vertical direction is stored inside.
The upper end of the coating agent discharge pipe 213 is a fixed end fixed to the lid body 212, and the lower end is a free end located near the bottom wall portion 2111.
The upper end of the coating agent discharge pipe 213 is connected to the discharge port 212a.
The coating agent supply device 2 of the present embodiment is configured such that when air is supplied from the air compressor 22 and the inside of the storage tank 21 is pressurized, the coating agent discharge pipe 213, the discharge port 212a, and the The moisture-proof coating agent W can be pumped to the nozzle 121 via the coating agent supply pipe 24.

The coating agent supply device 2 can be switched between an open state in which the moisture-proof coating agent W can flow through the coating agent supply pipe 24 and a closed state in which the moisture-proof coating agent W in the coating agent supply pipe 24 is prevented from flowing. The on-off valve V2 is provided.
The coating agent supply device 2 of the present embodiment is configured such that the pressure of the storage tank 21 can be released by the three-way valve V1.
Therefore, the on-off valve V2 provided in the coating agent supply pipe 24 functions to prevent the moisture-proof coating agent W from flowing backward when the pressure of the storage tank 21 is released.

  In this embodiment, the air compressor 22 for pumping the moisture-proof coating agent W is a general type such as a turbo type such as an axial flow type or a centrifugal type, or a volume type such as a reciprocating type or a rotary type. Can be adopted.

In order to ensure good transportability to the nozzle 121 that is the supply destination of the moisture-proof coating agent W, the moisture-proof coating agent W is pumped by applying a pressure (gauge pressure) of 0.1 MPa or more to the inside of the storage tank 21. It is preferably carried out by generating, more preferably carried out by generating a pressure of 0.13 MPa or more, and particularly preferably carried out by generating a pressure of 0.15 MPa or more.
However, even if an excessively high pressure is generated, the transportability of the moisture-proof coating agent W may not be so good as to meet the pressure. Therefore, the pressure is preferably less than 0.4 MPa, and less than 0.25 MPa. It is more preferable that
Therefore, it is desirable that the air compressor 22 has the ability to generate the pressure as described above inside the storage tank 21.

  The moisture-proof coating agent W fed under pressure in the present embodiment is not particularly limited, and a general one can be adopted.

As the moisture-proof coating agent, for example, a general one such as urethane, acrylic, olefin, silicone, fluorine, or rubber can be employed.
The moisture-proof coating agent is preferably selected from urethane, acrylic, olefin, and rubber.
The moisture-proof coating agent may be a solvent type containing an organic solvent or a water emulsion type containing an aqueous solvent.
As the moisture-proof coating agent, for example, a thermosetting type, an ultraviolet curing type, or a moisture curing type can be employed.

However, it is preferable that the moisture-proof coating agent of the present embodiment has good dispersibility as a constituent component. For example, a uniform dispersion state is maintained for 6 hours or more when left at room temperature (23 ° C.). It is more preferable that evenly dispersed state is maintained even if it is left standing for 24 hours or more.
Whether or not the moisture-proof coating agent is in a uniformly dispersed state is determined by, for example, storing 200 ml of the moisture-proof coating agent in a 200 ml capacity tall beaker, sealing it with a plastic paraffin film, and allowing it to stand for a predetermined time, The samples collected from the vicinity can be compared, and the solid content concentration contained in the moisture-proof coating agent can be compared between the samples.
More specifically, when the solid content concentrations of the two samples collected as described above are compared, for example, if the value on the higher concentration side is about 1.1 times the value on the lower side, the uniform dispersion state Can be determined to be maintained.

Since the moisture-proof coating agent W directly contacts the pressurized air inside the storage tank 21, more air than the saturated solubility under atmospheric pressure is present inside the storage tank 21. Dissolve in
That is, on the liquid surface Wa of the moisture-proof coating agent W, components such as oxygen, nitrogen, and carbon dioxide are taken into the liquid from the pressurized air, and these are in a supersaturated state with respect to the state under atmospheric pressure. Gas is taken in.
The gas taken in at the liquid level Wa is diffused into the moisture-proof coating agent in a dissolved state.
Thus, the air dissolved in the moisture-proof coating agent W is not released immediately from the moisture-proof coating agent W just because the pressurization inside the storage tank 21 is released.
Therefore, the coating agent supply apparatus 2 of the present embodiment includes the stirring device 23 as a deaeration device for deaerating dissolved air from the moisture-proof coating agent W.

The stirring device 23 includes a rotating shaft 231 that rotates around an axis, and a stirring blade 232 that is fixed to an end of the rotating shaft 231.
The stirring device 23 further includes a motor (not shown) for rotating the rotary shaft 231 around the axis.
The stirring device 23 of the present embodiment is configured such that the stirring blade 232 can stir the moisture-proof coating agent W in the vicinity of the bottom wall portion 2111.
As a general degassing method, vacuum degassing and heat degassing are known. However, the coating agent supply device 2 of the present embodiment applies physical stimulation to the moisture-proof coating agent W by the stirring device 23. It is configured to deaerate.

The reason why deaeration by stirring is effective in this embodiment is not clear, but one reason is considered to be a pressure difference inside the moisture-proof coating agent W.
More specifically, when the agitating blade 232 is revolved by rotation of the rotating shaft 231 inside the moisture-proof coating agent W, positive pressure is applied to the moisture-proof coating agent W in the circumferential direction of the stirring blade 232 and moisture-proof in the circumferential direction rearward. A negative pressure is applied to the coating agent W.
At this time, fine bubbles containing the solvent of the moisture-proof coating agent W and dissolved air are formed in the liquid by the negative pressure, and the solvent contained in the fine bubbles is again absorbed by the moisture-proof coating agent W when the negative pressure is released. However, the air that was in a supersaturated state becomes fine bubbles as it is and rises toward the liquid surface Wa, and the air bubbles rise while taking in the surrounding dissolved air. It is presumed that the deaeration is efficiently performed.
When vacuum degassing is performed by evacuating a space formed above the liquid surface Wa of the moisture-proof coating agent W in the storage tank 21, the rear of the stirring blade 232 is near the liquid surface Wa. Negative pressure will be applied in the same way.
However, in such vacuum degassing, the solvent of the moisture-proof coating agent W is actively discharged out of the storage tank, and it is difficult to remove dissolved air efficiently.
Moreover, as a result of the solvent being easily lost in the vacuum degassing, there is a possibility that the solute concentration of the moisture-proof coating agent W may be changed, but in the degassing by stirring, it is possible to suppress the occurrence of such a concentration change. The advantage can be demonstrated.

When the distance from the liquid surface Wa is longer, pressure is applied due to the weight of the liquid, so that the gas is easier to dissolve and more difficult to escape.
Further, in the deaeration by stirring, it is considered that it is advantageous that the moving distance is longer until the generated fine bubbles reach the liquid surface Wa.
Further, in the deaeration by stirring, it is preferable that the liquid level Wa is not excessively disturbed in order to prevent air from being entrained on the liquid level Wa.
For this reason, the stirring blade 232 is preferably located deeper than half of the distance h (hereinafter also referred to as “liquid depth”) from the liquid level Wa to the bottom wall portion 2111.
That is, the upper end of the stirring blade 232 is preferably located deeper than the distance h / 2 from the liquid level Wa, and more preferably located deeper than 2h / 3.
The stirring blade 232 is preferably of a type in which a swirl flow is formed inside the storage tank 21.

The deaeration device in the present embodiment is the stirring device 23 as described above. For example, as shown in FIG. 4, the stirring device 23 may be used even if a vibration device 23x that vibrates the moisture-proof coating agent W is used. The same deaeration effect as that when using can be obtained.
Examples of the vibration device 23x include a type including a vibrator having a piezoelectric element (electrostrictive element), an eccentric motor, and the like.
For example, the vibration device 23 x may be arranged on the bottom of the storage tank 21, and the vibrator may be arranged to directly vibrate the moisture-proof coating agent W with the vibrator. The vibrator may be attached to the outside of the wall portion 2111 or the body trunk portion 2112 to indirectly apply vibration to the moisture-proof coating agent W via the tank body 211.
An example of the vibrator is an ultrasonic vibrator.

The vibration of the vibrator acts to generate a pressure wave in the moisture-proof coating agent W.
Therefore, in the portion where the pressure wave is negative, fine bubbles containing air dissolved in a supersaturated state are generated as in the case of using the stirring blade 232, and deaeration from the moisture-proof coating agent W is performed. It will be.
In addition, after interrupting the pressure feeding of the moisture-proof coating agent W and performing the deaeration as described above, air is supplied again to the storage tank 21 to pressure-feed the moisture-proof coating agent W (hereinafter also referred to as “second pressure feeding”). ) Can be implemented.
At this time, when the second pumping is started, if the stirrer 23 (stirring blade 232) and the vibration exciter 23x (vibrator) are not sufficiently stopped, bubbles generated in the moisture-proof coating agent due to these are prevented. May be supplied to the coating apparatus 1.
Therefore, the second pumping is preferably started after the stirring blades and the vibrator are sufficiently stopped.

The air dissolved in the moisture-proof coating agent W at the time of pressure feeding before degassing (hereinafter also referred to as “first pressure feeding”) is efficiently removed from the moisture-proof coating agent W by the degassing treatment.
Further, the moisture-proof coating agent W supplied to the coating apparatus 1 by the second pumping is reduced in the dissolved amount of air, so that the wet coating film formed on the surface of the printed circuit board A or the wet coating is applied. It is possible to suppress the generation of bubbles in the process in which the film is cured and dried to form a moisture-proof film.
Therefore, the moisture-proof treatment equipment 100 of this embodiment is advantageous for producing a printed circuit board with a moisture-proof coating having excellent quality.

In the method for manufacturing a printed circuit board with a moisture-proof coating using the moisture-proof treatment facility 100 of the present embodiment, the moisture-proof coating is formed on the surface of the printed circuit board A by the moisture-proof coating agent W as described above, and the printed circuit board with the moisture-proof coating is formed. Is manufactured.
In the method for manufacturing a printed circuit board with a moisture-proof coating, the coating apparatus 1 applies the moisture-proof coating agent W to the surface of the printed circuit board A, and the coating agent supply apparatus 2 applies the moisture-proof coating agent W to the coating apparatus 1. A supply step of supplying the moisture-proof coating agent W, and the supply step includes a storage tank 21 in which the moisture-proof coating agent W is stored, and an air supply device 22 that supplies air to the storage tank 21. In addition, the coating agent supply device 2 is used, and the air is supplied to the storage tank 21 by the air supply device 22, and the inside of the storage tank 21 is pressurized by the air so that the coating is performed from the storage tank 21. The moisture-proof coating agent W is pumped to the device 1, and the pumping is performed a plurality of times including a first pumping and a second pumping performed after the first pumping. A deaeration process for releasing the dissolved air from the moisture-proof coating agent W housed in the housing tank 21 by releasing the pressurization of the housing tank 21 between the pumping and the second pumping. In the deaeration process, at least one of vibration to the moisture-proof coating agent W and stirring of the moisture-proof coating agent W is performed.

In the first embodiment, the first pressure feeding is performed at a pressure of 0.1 MPa (gauge pressure) inside the storage tank 21 in order to realize quick movement of the moisture-proof coating agent W from the coating agent supply device 2 to the coating device 1. It is preferable to carry out by generating the above pressure.
The first pumping is more preferably performed by generating a pressure of 0.13 MPa or more in the storage tank 21, and particularly preferably performed by generating a pressure of 0.15 MPa or more.

The second pumping of the present embodiment is also preferably performed by generating a pressure of 0.1 MPa (gauge pressure) or more inside the storage tank.
The second pumping is more preferably performed by generating a pressure of 0.13 MPa or more in the storage tank 21, and particularly preferably performed by generating a pressure of 0.15 MPa or more.

  In addition, it is preferable that the said pressure in 1st pumping or 2nd pumping is less than 0.4 MPa, and it is more preferable that it is less than 0.25 MPa.

The deaeration process is preferably performed after the pressure inside the storage tank 21 is reduced to atmospheric pressure.
If necessary, the deaeration process may be performed in a state where the inside of the storage tank 21 is slightly depressurized from the atmospheric pressure (for example, −0.01 MPa or more and less than 0 MPa).
In the deaeration process, if the atmospheric pressure is reduced more than the pressure in the first pumping, the inside of the storage tank 21 is slightly pressurized from the atmospheric pressure (for example, more than 0 MPa and 0.01 MPa or less). ).

In the present embodiment, the case where the coating agent supply device 2 is provided with the stirring device 23 and the vibration device 23x is illustrated, but in the method for manufacturing a printed circuit board with a moisture-proof coating as described above, Even if such a device is not provided in the coating agent supply device 2 in advance, the deaeration process can be performed.
In the deaeration process, for example, the lid 212 is removed from the tank body 211 to open the storage tank 21, and the moisture-proof coating agent stored in the tank body 211 is stirred using a separately prepared stirring device in this state. You may implement by the method to do.

The timing of the transition from the first pumping to the deaeration process can be set by timer control or control of the remaining amount of the moisture-proof coating agent W.
Further, a new moisture-proof coating agent (a new liquid in which no air is dissolved) may be replenished to the storage tank 21 before the second pumping after the deaeration process.
That is, in the present embodiment, after the deaeration process and before the moisture-proof coating agent is pumped, a new moisture-proof coating agent having a lower dissolved air concentration than the moisture-proof coating agent subjected to the deaeration process is stored in the storage tank. The step of adding to 21 (coating agent replenishment step) may be performed.
In the coating agent replenishment step, since a new moisture-proof coating agent having a smaller dissolved air amount is added to the moisture-proof coating agent that has been subjected to the deaeration process, the dissolved air of the moisture-proof coating agent contained in the storage tank 21 is used. The concentration is further lowered than immediately after the deaeration process.
Therefore, by carrying out such a coating agent replenishment step, it is possible to further prevent air bubbles from being mixed into the moisture-proof coating.

  Here, detailed description will not be repeated any more, but the present invention is not limited to the above-described examples, and the specific examples illustrated above are provided as long as the effects are not significantly impaired. Various modifications can be made to this embodiment.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

As a coating apparatus used for the evaluation, a coating apparatus in which a coating nozzle (product name “A7A film coat gun” manufactured by Nordson Co., Ltd.) was set on the main body (model name “TCM45A” manufactured by TTnS) was prepared.
Along with this, a moisture-proof coating agent (product name “LSS-520MHF-K” manufactured by Nitto Shinko Co., Ltd.) was prepared.

(Evaluation A: Leave at atmospheric pressure)
The moisture-proof coating agent is put in a container (open container: manufactured by Kinki Container Co., Ltd., product name “Hi-pack container No. 150”) and stored under a pressure condition of 0.25 MPa for a total of 24 hours. Coating was performed under the conditions of a coating width of 8 mm and a coating speed of 400 mm / second to form a wet coating film, which was then dried at room temperature to form a moisture-proof coating.
Moreover, the dissolved oxygen concentration of the moisture-proof coating agent immediately after storing for 24 hours was measured.
Many bubbles were observed in the moisture-proof coating at this time (see FIG. 5a).
Moreover, the dissolved oxygen concentration (DO) measured at this time was 11.2 mg / l.

Next, the dehumidifying treatment is carried out by storing the moisture-proof coating agent in an open container at atmospheric pressure for 24 hours. Using the moisture-proof coating agent after the degassing treatment, the formation of a moisture-proof film and the dissolved oxygen concentration are performed again. And measured.
As a result, the dissolved oxygen concentration decreased to 10.0 mg / l, and although the mixing of bubbles into the moisture-proof coating was reduced, the effect was not sufficient (see FIG. 5b).

(Evaluation B: Heat degassing)
The moisture-proof coating agent is put in a container (open container: manufactured by Kinki Container Co., Ltd., product name “Hi-pack container No. 150”), and stored at room temperature (23 ° C.) and 0.25 MPa for a total of 24 hours. The coating was performed under the conditions of a nozzle height of 8 mm, a coating width of 8 mm, and a coating speed of 400 mm / second to form a wet coating film, which was then dried at room temperature to obtain a moisture-proof coating.
Moreover, the dissolved oxygen concentration of the moisture-proof coating agent immediately after storing for 24 hours was measured.
A large number of bubbles were observed in the moisture-proof coating at this time, as in “Evaluation A” (see FIG. 6a).
Moreover, the dissolved oxygen concentration (DO) measured at this time was 10.5 mg / l.

Subsequently, the deaeration treatment was performed by storing the moisture-proof coating agent in an open container for 1 hour in an oven set at a temperature of 40 ° C. (atmospheric pressure is atmospheric pressure).
At this time, the temperature of the moisture-proof coating agent reached 40 ° C. 30 minutes after the start of storage in the oven.
After cooling for 1 hour after the deaeration treatment by heating, the temperature of the moisture-proof coating agent was 27 ° C.
Using the moisture-proof coating agent after the deaeration treatment, the moisture-proof coating was formed again and the dissolved oxygen concentration was measured.
As a result, the dissolved oxygen concentration decreased to 9.7 mg / l, and although the mixing of bubbles into the moisture-proof coating was reduced, the effect was not sufficient (see FIG. 6b).

(Evaluation C: Stirring deaeration)
The moisture-proof coating agent is put in a container (open container: manufactured by Kinki Container Co., Ltd., product name “Hi-pack container No. 150”), and stored at room temperature (23 ° C.) and 0.25 MPa for a total of 24 hours. The coating was performed under the conditions of a nozzle height of 8 mm, a coating width of 8 mm, and a coating speed of 400 mm / second to form a wet coating film, which was then dried at room temperature to obtain a moisture-proof coating.
Moreover, the dissolved oxygen concentration of the moisture-proof coating agent immediately after storing for 24 hours was measured.
Many bubbles were observed in the moisture-proof coating at this time, as in “Evaluation A” and “Evaluation B” (see FIG. 7a).
Moreover, the dissolved oxygen concentration (DO) measured at this time was 10.9 mg / l.

Next, the moisture-proof coating agent was stirred for 5 minutes under atmospheric pressure to carry out deaeration treatment.
Using the moisture-proof coating agent after the deaeration treatment, the moisture-proof coating was formed again and the dissolved oxygen concentration was measured.
As a result, even with stirring for only 5 minutes, it was possible to confirm the effect exceeding the 1 hour heating deaeration in “Evaluation B”, and the dissolved oxygen concentration was reduced to 9.6 mg / l.
Moreover, the mixing of air bubbles into the moisture-proof coating was greatly reduced (see FIG. 7b: almost no air bubbles can be confirmed).

  From the above, it can be seen that according to the present invention, formation of bubbles can be suppressed when a moisture-proof coating is formed with a moisture-proof coating agent.

DESCRIPTION OF SYMBOLS 1: Coating apparatus 2: Coating agent supply apparatus 11: Stage part 12: Coating part 21: Storage tank 22: Air compressor 23: Stirrer 100: Moisture-proof equipment 211: Tank main body 212: Lid 212a: Discharge port 2111 : Bottom wall part 2112: Main body trunk part 2121: Ceiling part 2122: Cover trunk part A: Printed circuit board W: Dampproof coating agent

Claims (6)

A storage tank for storing a moisture-proof coating agent for forming a moisture-proof coating on the printed circuit board;
An air supply device for supplying air to the storage tank,
A coating agent supply device in which the moisture-proof coating agent is pumped from the storage tank toward the supply destination of the moisture-proof coating agent by supplying the air from the air supply device to the storage tank,
The storage tank is switchable between a pressurized state in which the inside is pressurized by the air and a pressurized release state in which the pressure is released,
A vibration device that vibrates the moisture-proof coating agent stored in the storage tank in the pressure release state, and agitation that stirs the moisture-proof coating agent stored in the storage tank in the pressure release state A coating agent supply apparatus further comprising at least one of the apparatuses.   The coating agent supply apparatus according to claim 1, wherein the vibration device includes a vibrator for vibrating the storage tank.   The coating agent supply device according to claim 1, wherein the stirring device includes a stirring blade for stirring the moisture-proof coating agent.   The coating agent supply apparatus according to any one of claims 1 to 3, wherein the pressure-proof feeding of the moisture-proof coating agent to the supply destination is performed by generating a pressure of 0.1 MPa or more inside the storage tank. A method for producing a printed circuit board with a moisture-proof coating, wherein a moisture-proof coating is formed on the surface of the printed circuit board by a moisture-proof coating agent to produce a printed circuit board with a moisture-proof coating,
An application step of applying the moisture-proof coating agent to the surface of the printed circuit board with a coating apparatus;
A supply step of supplying the moisture-proof coating agent to the coating device with a coating agent supply device,
In the supply step, the coating agent supply device including a storage tank that stores the moisture-proof coating agent and an air supply device that supplies air to the storage tank is used.
The air is supplied to the storage tank by the air supply device, the interior of the storage tank is pressurized by the air, and the moisture-proof coating agent is pumped from the storage tank to the coating device,
The pumping is performed a plurality of times including a first pumping and a second pumping performed after the first pumping,
A deaeration process for releasing the dissolved air from the moisture-proof coating agent stored in the storage tank by releasing the pressurization of the storage tank between the first pumping and the second pumping. Is implemented,
In the degassing treatment, a method for producing a printed circuit board with a moisture-proof coating, wherein at least one of vibration to the moisture-proof coating agent and stirring of the moisture-proof coating agent is performed.   The method for manufacturing a printed circuit board with a moisture-proof coating according to claim 5, wherein the first pumping is performed by generating a pressure of 0.1 MPa or more inside the storage tank.