JPS6034093A - Method of coating liquid varnish on printed circuit board and coating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a method for applying liquid varnish to a printed circuit board and a method for applying varnish to the printed circuit board for the purpose of preventing dust, corrosion, migration, and whisker. Regarding equipment.

[Background of the invention]

In conventional liquid paint coating methods, the following steps are taken to speed up coating.

That is, the nozzle front pressure is set to 5 to 200 Ky/tri.
As shown in Figure 1 (4), the paint is discharged from the discharge nozzle 1 into a wide-angle conical shape 2 in a completely atomized state, or as shown in Figure 1 (To). The liquid is discharged from the discharge nozzle 1 in a substantially bell-shaped form 3 in an incompletely exposed state, so as to apply the liquid over a wide area to an object to be coated (not shown).

However, if the discharge nozzle 1 is discharged in the shape shown in FIG. A masking process is required to block the sprayed paint on the part.

Therefore, when applying varnish to a printed circuit board using the above-mentioned conventional technique, it is necessary to mask the areas where coating is prohibited, and depending on the shape and number of areas where coating is prohibited, there is a drawback that the coating work ability is significantly reduced. Ta.

[Purpose of the invention]

An object of the present invention is to prevent the occurrence of varnish mist, and therefore, even if the printed circuit board has areas where coating is prohibited,
It is an object of the present invention to provide a method for applying liquid varnish to a printed circuit board, which allows liquid varnish to be applied to the prohibited areas without masking, and another object of the present invention is to provide a coating device that can reliably carry out the method. It is in.

[Summary of the invention] The method of the present invention includes adjusting the varnish viscosity to 3 to 100 CPS under a temperature condition of 0 to 40 C, adjusting the varnish discharge pressure to 0.3 to 1.0 Kg/crA at the nozzle front pressure,
Based on these values, the nozzle diameter was adjusted to 0.20 to 0.25φ in terms of the diameter on the same side, and the liquid varnish was discharged from the discharge nozzle in the shape of a bamboo leaf and applied to the printed circuit board. This method is unique in that it is possible to prevent the occurrence of varnish mist, and as a result, it is possible to apply liquid varnish to areas of the printed circuit board where application is prohibited without masking.

The apparatus of the present invention comprises a varnish viscosity control means for adjusting the varnish viscosity of the liquid varnish supplied to a discharge nozzle, a nozzle front pressure control means for adjusting the nozzle front pressure of the liquid varnish, the varnish viscosity control means and the nozzle front pressure control. The varnish viscosity control means, the nozzle front pressure control means, and the nozzle diameter control means control the liquid varnish from the discharge nozzle to the bamboo grass. This method is characterized by being configured to be discharged in the form of leaves, which makes it possible to reliably carry out the method described above.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

2 and 3 show an embodiment of an apparatus for carrying out the method of the invention.

The liquid varnish coating device shown in these figures includes a varnish tank 4 that stores liquid varnish 5, a pressure pump 7 connected to this through a supply pipe 6, and a cooling/heating device connected to the pressure pump 7 through a supply pipe 6. 8. A flow rate detector 9 installed in the supply pipe 6 between the pressure pump 7 and the cooler/heater 8;
A first pipe provided in the supply pipe 6 before and after the cooling/heating device 8
．． A second temperature detector io, ii, a discharge nozzle 12 connected to the cooling/heating device 8 through the supply pipe 6, and a pressure detector 14 provided in the return pipe 13 connecting the discharge nozzle 12 and the varnish tank 4. , a constant pressure maintenance valve 15 provided in the same return pipe 13, a constant temperature controller 16 that controls the cooling/heating device 8, and a constant pressure maintenance controller 1 that controls the constant pressure maintenance valve 15.
7, a constant pressure controller 18 that controls the pressure pump 7 and the constant pressure maintenance controller 17; and a nozzle opening/closing controller 19 that controls the discharge nozzle 12.

The cooling/heating device 8 and the first. Second temperature sensor 10.11
and the constant temperature controller 16 constitute varnish viscosity control means for adjusting the varnish viscosity of the liquid varnish supplied to the discharge nozzle 12. In this varnish viscosity control means, the second
As shown in the figure, a first temperature detector 10 detects the temperature of the liquid varnish before it enters the cooling/heating device 8, and sends the temperature signal A to a constant temperature controller 16. Further, the second temperature detector 1 detects the temperature of the liquid varnish discharged from the cooler/heater 8 and sends the temperature signal B to the constant temperature controller 6. Then, as shown in FIG. 3, the constant temperature controller 16 outputs a temperature signal A.
, B, and compares the temperature signal B from the second temperature detector 11 with the target value to calculate the control amount necessary for constant temperature control. Temperature indication signal (control signal) to be sent to the heater and cooler
produce. In the cooler/heater 8, a constant temperature controller 16
The varnish viscosity of the liquid varnish to be supplied to the discharge nozzle 12 is adjusted by heating or cooling the liquid varnish according to the temperature instruction signal sent from the discharge nozzle 12 .

The flow rate detector 9, pressure detector 14, constant pressure maintenance valve 15, constant pressure maintenance controller 17, and constant pressure controller 18 control the nozzle pressure of the liquid phenol to 1. [Pre-nozzle pressure control means is configured. In this nozzle front pressure control means, as shown in FIG. 2, the flow velocity at the outlet of the pressure pump 7 is detected by the flow velocity detector 9, and the detected flow velocity signal is sent to the constant pressure controller 18. On the other hand, the pressure detector 14 detects the pressure in the return pipe 13 between the discharge nozzle 12 and the constant pressure maintenance valve 15, and sends the pressure signal to the constant pressure controller 18. Next, as shown in FIG. 3, the constant pressure controller 18 calculates the flow rate of the liquid phenol entering the discharge nozzle 12 from the flow rate signal and the pressure signal,
The flow rate is compared with the target value, the comparison result is converted to pressure, the pressure in front of the nozzle is detected from this pressure force, the control amount necessary to control the pressure in front of the nozzle at a constant pressure is calculated, and the pressure pump 7 and a constant pressure maintenance valve opening/closing signal to be transmitted to the constant pressure maintenance controller 17. The pressure feed pump 7 controls the flow rate of liquid varnish sent to the discharge nozzle 12 based on the pressure feed amount control signal from the constant pressure controller 18, and the constant pressure maintenance controller 17 receives a constant pressure maintenance valve opening/closing signal from the constant pressure controller 18. constant pressure maintenance valve 1
5, and controls the opening/closing amount of the pressure pump 7 and the constant pressure maintenance valve 1.
5, the nozzle front pressure is adjusted.

As shown in FIG. 3, coordinate information and application information are sent to the nozzle opening/closing controller 19 as a nozzle diameter control means. Here, the coordinate information is information that shows either the varnish viscosity or the nozzle front pressure on the horizontal axis and the other on the vertical axis, and also indicates the relationship between the varnish viscosity, the nozzle front pressure, and the nozzle diameter. (See Figures 6 to 10).

Further, the coating information is information on the actually adjusted varnish viscosity and nozzle front pressure. In the nozzle opening/closing controller 19,
The coordinate information and application information are taken in, and then converted into opening/closing information for the discharge nozzle 12, and furthermore, the liquid varnish can be discharged from the discharge nozzle 12 in the shape of a bamboo leaf, the discharge shape is stable, and there is no rebound from the printed circuit board. The nozzle diameter that allows the discharge to be avoided is calculated, the discharge nozzle opening/closing control amount is created based on the calculated nozzle diameter, and the opening/closing signal is sent to the discharge nozzle 12.

Next, an embodiment of the coating method according to the present invention will be described in relation to the operation of the coating device.

The liquid varnish 5 stored in the varnish tank 4 is sucked up by the pressure pump 7 and sent through the supply pipe 6 to the cooler/heater 8, and the varnish viscosity is adjusted by the cooler/heater 8. Then, the discharge nozzle 121C is sent.

Meanwhile, the temperature of the liquid phenol before entering the cooler/heater 8 is detected by the first temperature sensor 10, and the temperature signal is sent to the constant temperature controller 16, and the temperature signal is sent to the second temperature sensor 11. The temperature of the liquid phenol discharged from the cooler/heater 8 is detected,
The temperature signal is sent to constant temperature controller 16. In the constant temperature controller 16, the first. A temperature instruction signal to control the cooler and heater of the cooler/heater 8 is generated from the temperature signal sent from the second temperature detector 10.11, and the temperature instruction signal is used to control the cooler and heater. The liquid varnish is sent to the cooler and heater 8, which includes a cooler and a heater, to a temperature of O to 40C.
The varnish viscosity is adjusted to 3 to 100 CPS under the conditions of .

On the other hand, the flow rate of the liquid phenol discharged from the pressure pump 7 is detected by the flow rate detector 9, and the flow rate signal is sent to the constant pressure controller 18.
sent to. In addition, the pressure detector 14 detects the discharge nozzle 1.
2, the pressure of the liquid phenol returned to the varnish tank 4 through the return pipe 13 is detected, and the pressure signal is sent to the constant pressure controller 1.
Sent to 8th. This constant pressure controller 18 calculates the pressure of the fluid phenol entering the discharge nozzle 12 from the flow velocity signal sent from the flow velocity detector 9 and the pressure signal sent from the pressure detector 14, and uses this pressure to calculate the pressure of the fluid phenol entering the discharge nozzle 12. A pumping amount control signal that controls the discharge flow rate of the pump 7 and a constant pressure maintenance controller 17
Create a constant pressure maintenance valve opening/closing signal for t-control. Next, the pressure feeding amount control signal is sent to the pressure pump 7.
The constant pressure maintenance valve opening/closing signal is sent to the constant pressure maintenance controller 17, and the constant pressure maintenance controller 17 controls the opening degree of the constant pressure maintenance valve 15. By controlling the discharge flow rate of the pressure pump 7 and the opening degree of the constant pressure maintenance valve 15, the nozzle front pressure of the discharge nozzle 12 is reduced to 0.
．． 3-1. Adjusted to OK5+/crl.

Next, the nozzle opening/closing controller 19 receives coordinate information indicating the relationship between varnish viscosity, nozzle front pressure, and nozzle diameter, and coating information that is the actually adjusted value. Based on the information, a nozzle opening/closing signal is generated to control the nozzle diameter of the discharge nozzle 12 to an appropriate value within the range of 0.2 to 0.25φ in terms of area and other diameter values. This nozzle opening/closing signal is sent to the discharge nozzle 12, and the nozzle diameter is adjusted to an appropriate value within the range of 0.20 to 0.25φ.

As a result, the varnish is ejected from the ejection nozzle 12 in the shape of a bamboo leaf as shown in Figure 4, and in a thinner thickness as shown in Fig. 5, and in a stable shape, and it does not bounce off the printed circuit board. It is discharged as follows. In addition, the varnish discharged in FIGS. 4 and 5 is designated by reference numeral 2.
Indicated by 0.

Next, FIGS. 6 to 10 show experimental results regarding the relationship between varnish viscosity, nozzle front pressure, and nozzle diameter that can discharge liquid varnish in the shape of a bamboo leaf.

In the experimental results shown in FIGS. 6 to 10, the varnish temperature is θ to 40 C, and the nozzle diameter is expressed as the diameter of a circle equivalent in area.

The area indicated by diagonal lines in Figure 6, viscosity of the nail polish = 10CP8 or less, nozzle front pressure 0.3Kg/cr
Under the conditions of I or less and nozzle diameter = 0.20φ or less, the discharge shape was unstable and unsuitable.

Next, the area indicated by diagonal lines in FIG. 7, that is,
Varnish viscosity = 3-1000P8, nozzle front pressure = 0.3
~1.0 Ni/Ca, nozzle diameter = 0.20~0.25
Under the condition of φ, a stable discharge shape was obtained, there was no rebound from the printed circuit board, and the discharge state was appropriate.

In addition, the area indicated by hatching in the 8th section, that is, varnish viscosity = 1o ~ 500CPS, nozzle front pressure = 1.0 ~ 2
．． Conditions of 0~/Cfnz nozzle diameter = 0.25~0.33φ, the shaded area in Fig. 9, that is, varnish viscosity = 20~about 13000 PS, nozzle front pressure = 2.0
~3. OK9/cd1 nozzle diameter = 0.33~0.43φ
conditions, and the area shown with diagonal lines in Fig. 10, Tsuma Shiwanisu viscosity = 30 to 2000 cps, nozzle front pressure = 3.0 to 4.0 Kg/crl 1 nozzle diameter =
The conditions of 0.43 to 0.56φ were unsuitable because the outflow speed of the discharged varnish was too fast, causing the varnish to collide with the printed circuit board and further bounce back and scatter.

Next, FIGS. 11 and 12 (4), (g), and (Q) show the state in which liquid varnish is applied to a printed circuit board by applying the present invention.

Figure 11 shows varnish 2 in the shape of a bamboo leaf from the discharge nozzle 12.
0 is ejected, and the printed circuit board 21 and the ejection nozzle 12 are relatively moved in one direction as shown by the arrow to apply the liquid.

In addition, the printed circuit board 21 on which the electronic component 22 is mounted is placed on the XY table 23 using two discharge nozzles 12a and 12b arranged at a set interval t. At first, as shown in FIG.
b is discharged, and the XY table 23 is moved in the Y direction →Y2 direction to apply the product. At that time, as shown in FIG.
2' may occur. Next, move the XY table 23 so that the first coating surface matches the discharge nozzle Ill.)
'+' Distance t between discharge nozzles 12a and 12b in the X2 direction
As shown in FIG. 12, the varnish 20a is discharged from the discharge nozzle 12a, and the XY table 23 is moved in the Y2→Yt direction to apply the varnish. Thereby, it is possible to apply varnish even to the non-applied surface 22' of the electronic component 22.

These Figures 11 and 12 (4), (13),
In the application state shown in (C), as described above, the festival viscosity = 3 to xoocps, and the nozzle front pressure = 0.
, 3-1.0 K9/Cd, nozzle diameter = 0.2-0.
By adjusting the diameter to 25φ, it is possible to apply the varnish in a stable form and in an appropriate state without rebounding from the printed circuit board 21. Therefore, the varnish can be applied as a spray paint to areas where application is prohibited. Varnish can be applied without masking.

In the present invention, the varnish viscosity control means, the nozzle front pressure control means, and the nozzle diameter control means are not limited to the embodiments shown in FIGS. 2 and 3, but may be any means having the desired functions.

〔Effect of the invention〕

According to the method of the present invention explained above, the varnish viscosity is 0 to 4.
Adjust the varnish discharge pressure to 3-100 CPS under the temperature condition of 0C, and the varnish discharge pressure to 0.3-1.0 Kg at the nozzle front pressure.
/ cr / l K is adjusted, and based on these values, the nozzle diameter is adjusted to 0920 to 0.25φ in the diameter value of the area measurement, and the liquid varnish is discharged from the discharge nozzle in the shape of a bamboo leaf.
Since the varnish is applied to the printed circuit board, the varnish can be ejected from the dispensing nozzle in a stable shape without bouncing back from the printed circuit board. It has the effect of being applied.

Further, according to the device of the present invention, varnish viscosity control means for adjusting the varnish viscosity of the liquid varnish supplied to the discharge nozzle;
A nozzle front pressure control means for adjusting the nozzle front pressure of the liquid varnish, and a nozzle diameter control means for adjusting the diameter of the discharge nozzle based on control values from the varnish viscosity control means and the nozzle front pressure control means, By means of varnish viscosity control means, nozzle front pressure control means and nozzle diameter control means,
Since the liquid varnish is configured to be discharged from the discharge nozzle in the shape of a bamboo leaf, there is an effect that the method of the present invention can be carried out reliably.

[Brief explanation of the drawing]

Fig. 1 (4) and ■ are explanatory diagrams of the prior art, Fig. 2 is a block diagram showing an embodiment of a device implementing the method of the present invention, and Fig. 3 is a block diagram showing details of the controller. figure,
Figures 4 and 5 are front and side views of the discharge shape of the varnish obtained by the present invention, and Figures 6 to 10 respectively show experimental results regarding the relationship between varnish viscosity, nozzle front pressure, and nozzle diameter. Figures 11 and 12 (
4), ■. 0 is a diagram showing a state in which varnish is applied to a printed circuit board by applying the present invention. 4... Varnish L5... Liquid varnish, 7... Pressure pump, 8... Cooler/heater, 9 River flow rate detector, 10.1
1... 1st. 2nd temperature detector, 12...Discharge nozzle, 14...Pressure detector, 15 River constant pressure maintenance valve, 16...
・・ Constant temperature controller, 17 ・・ Constant pressure maintenance controller, 18 ・・
- Constant pressure controller, 19... Nozzle opening/closing controller, 2o River bamboo leaf-shaped discharge varnish, 21... Printed circuit board. Agent: Patent attorney Masami Akimoto 7? 2nd figure 4 cup ji 50th month 120th (phantom (C)

Claims (1)

[Claims] 1. The varnish viscosity is 3 to xoo under the temperature condition of 0 to 40C.
cpsvcm, adjust the nozzle front pressure of varnish discharge pressure to 0.3 to 1.0 Kg/cl, and based on these values, set the nozzle diameter to 0.20 in the diameter value for area equalization.
A method for applying a liquid varnish to a printed circuit board, the method comprising adjusting the diameter to 0.25φ, discharging the liquid varnish from a discharge nozzle in the shape of a bamboo leaf, and applying the liquid varnish to the printed circuit board. 2. Varnish viscosity control means for adjusting the varnish viscosity of the liquid varnish supplied to the discharge nozzle; nozzle front pressure control means for adjusting the nozzle front pressure of the liquid varnish; and a nozzle diameter control means for adjusting the diameter of the discharge nozzle based on the control value. 1. A device for applying liquid varnish to a printed circuit board, characterized in that the device is configured to discharge liquid varnish to a printed circuit board.