JPS63194390A - Apparatus for forming film of electronic circuit substrate - 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 (Industrial Application Field) The present invention relates to an apparatus for forming a film on an electronic circuit board, and more specifically, a method for airlessly spraying molten resin onto a circuit board in which a large number of electronic circuit components are incorporated. The present invention relates to an apparatus for forming an insulating film.

(Prior art) Conventionally, acrylic resin has been applied to electronic circuit boards to form a film for insulation or moisture proofing, and film coating methods or air spray methods have been used for this purpose. It is being As for the film coating method, the Nordson film coating method manufactured by Nordson Corporation in the United States is well known, and this method sprays molten resin in the form of a film from a nozzle 200 onto an electronic circuit board, as shown in FIG. It is to be coated. In addition, in the air spray method, as shown in FIG. 15(C), molten resin is atomized and sprayed using compressed air for coating.

(Problem to be Solved by the Invention) However, in any of the above methods, the feeding pitch and moving speed of the injection nozzle relative to the electronic circuit board are always constant, and therefore, the amount of coating per unit area on the board is constant. The spray nozzle must always be moved at the same feed pitch even for locations with different effective areas, resulting in uneven coating film thickness and waste of resin or solvent. The effective area of the coating may vary depending on the size and height of the components on the board and the degree of integration.
The coating area is determined by the presence or absence of parts such as PU and connectors that are highly important for insulation and moisture-proof leaks.

Therefore, if the feed pitch and movement speed are set to match the required minimum thickness, the flat surface will be coated unnecessarily thickly, wasting resin and solvent, and the unnecessary thickness will easily cause liquid dripping. In addition to lowering the marketability, there was also the inconvenience that the substrate could not be turned over and the backside coating operation could not be carried out promptly. In addition, in order to avoid liquid blurring, the substrate must be dried using a heater, fan, etc. while being held horizontally, resulting in a problem that the length of the drying process line becomes long.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to variably control the feed pitch of the airless spraying means according to the effective area of the coating, thereby causing uneven coating and liquid blurring. Provides a coating forming device for electronic circuit boards that has improved marketability, can perform coating of desired thickness with minimum consumption of resin and solvent, and requires short drying line length. It's about doing.

(Means for Solving the Problems) In order to solve the above object, a film forming apparatus for an electronic circuit board according to the present invention includes a positioning means for positioning the electronic circuit board at a predetermined position, and a positioning means for positioning the electronic circuit board at a predetermined position, a drying means for drying the electronic circuit board after the airless spraying; and a drying means for drying the electronic circuit board after the airless spraying. In addition to having a drive means for moving the airless injection means in the direction, the feed pitch of the airless injection means is made variable.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows the overall configuration of this device. As shown in the figure, this device includes a transport section A, a model discrimination section B, a first injection section C1, an inversion section D,
It consists of a second injection section E, an initial drying section F, and a second drying section G. Furthermore, this device includes a control unit 1 consisting of a computer.
0, and each part of this device operates in response to a control command according to a program stored in the control unit 10. This will be explained below.

The transport section A is composed of a rail 12 and a transport claw 14, and an electronic circuit board 16 (hereinafter abbreviated as "board") attached to a housing of an electronic control unit of an automobile, etc. is placed on the rail 12. It is configured to be pushed by a conveying claw 14. The conveyance claw 14 is operated according to a command from the control unit 10 as described later.
It is configured to rise from a resting position under the rail 12, move forward and push the board 16 on the rail 12 a predetermined distance, then descend and return to the resting position. Incidentally, a driving means such as a motor for driving this conveying claw 14 is omitted from illustration.

The model determination section B includes a light transmission sensor section 18. As shown in the figure, the sensor section 18 is installed on the side of the rail 12, and is composed of three light receiving elements 18a, 18b, and 18c such as phototransistors that receive light from a light source (not shown). . The three light-receiving elements are arranged in parallel in the direction of board movement, and the output varies depending on the state of blocking transmitted light due to the shape of the casing in which the board is attached, and the signal line (not shown)
is sent to the control unit 10 via. Therefore, the control unit 10 can determine the type of board from the output.

The first injection part C is equipped with an abutment clamp 20 and a holding clamp 22, as shown in FIG. is configured to be fixed in a predetermined position by pressing it from both sides. Fig. 5 shows details of the abutting clamp 20 (holding clamp 22), and the outer case 20a (
22a), an inner case 2b (22b) housed therein, and a rod 20c (22c) attached to the tip of the inner case, and the control unit 1
When compressed air or hydraulic pressure is sent from a power supply source (not shown) in response to a command from the inner case 20b (
22b) is configured to move forward and bring the iron 22C into contact with the housing to which the board 16 is attached. Note that FIG. 1 is shown in a simplified manner for convenience of illustration.

The first injection section C further includes an injection mechanism 26.

The injection mechanism 26 includes an X-axis arm 28 that is movable in the substrate advancing direction, a Y-axis arm 30 that is attached perpendicularly to the arm 28 and movable in the transverse direction, and the Y-axis arm 30.
It consists of an injector 32 attached to. As shown in FIG. 1, the injector 32 is connected to a resin tank 36 via a pressure-feeding pipe 34, and the resin tank 36 stores a mixture of acrylic resin for recording and a solvent consisting of toluene/xylene. ing. A drive source 3 is connected to the pressure-feeding pipe 34 that connects the resin tank 36 and the injector 32.
A pump 40 that operates by obtaining driving force from compressed air or the like from 8 is inserted, pressurizes the resin in the resin tank 36 to a predetermined pressure, and pumps the resin to the injector 32. A surge tank 41 is provided in the pressure feeding path to remove hydraulic pulsations generated by the pump 40 and supply resin at a -tail hydraulic pressure. Further, a heater 42 is inserted in the pressure feeding path to control the temperature, more specifically the viscosity, of the pumped resin to a set value, and a regulator 44 is inserted to control the liquid pressure at a constant level. Further, a return side pipe 46 is connected to the injector 32 in parallel with the pumping side pipe 34, and the molten resin is configured to circulate through the injector 32 via both pipelines 34 and 46. In addition, the code 4B is a filter, and the code 50 is a filter.
indicates a distributor. Further, an exhaust duct 52 is provided below the rail 12 to recover toluene and the like contained in the molten resin. Although not shown, in this device, the upper part of the rail 12 is covered with a housing and is isolated from the outside air.

Here, regarding the injection mechanism 26 described above, FIGS.
To further explain with reference to FIG. 0, the X-axis arm 28
As shown in the figure, a slider 28b is connected to a threaded rod 28a by a ball screw, and the slider 28b is moved as the threaded rod is rotated by a servo motor 28d connected via a coupling 28c. As shown by the imaginary line in the figure, the Y-axis arm 30 is attached to the slider 28b of the X-axis arm, and the injector 32 described above is mounted on the slider 30b of the Y-axis arm 30 on the mounting member 5.
It is attached via 4. Figure 8 shows this injector 32.
2 is a sectional view showing details of the piston rod 32a, in which a piston rod 32a is housed, and a valve 32b is provided at the tip thereof. The spring 32c biases the valve 32b in the closing direction via the piston rod 32a, and when the solenoid valve 32d opens and compressed air is supplied from the air supply source 32e, the valve 32b is pushed upward and the circulating resin is is guided into the passage 32f, and the cat's eye 3 of the nozzle 32g
It is injected from 2h. FIG. 9 shows the eighth part of the nozzle 32g.
It is a front view seen from the board|substrate 16 side in a figure. As shown in the figure, the cat's eye 32h is formed in the shape of a long hole, and its diameter in the width direction is slightly increased near the center.

Moreover, FIG. 10 shows its injection pattern.

Returning to the description of the entire apparatus, the reversing section includes a reversing mechanism 60 as shown in FIG. 12 (omitted in FIG. 1 for convenience of illustration). The reversing mechanism 60 includes plate bodies 62 . 62 and a rotary disk 64 which is rotatable from the plate body inside it and is similarly arranged oppositely.
．． Consists of 64.

The plate body 62 and the rotating disk 64 have a circular shape and a
A letter-shaped opening is bored, and a rail 12a is passed through the rack at an appropriate position of the letter-shaped opening on the side of the rotating disk. Note that this rail 12a is separated from the rails 12 before and after the reversing portion.

Furthermore, a pulley 66 is provided on the side of the rotary disk 64, and a belt 68 is passed around it.When the pulley 66 rotates in accordance with the rotation of the motor 70, the rail 12 is rotated accordingly.
It is configured to rotate the substrate 16 on a. In addition, the reference numeral 72 indicates a limit switch, and the reference numerals 74 and 74 indicate protrusions. During rotation, the protrusion 74 contacts the limit switch 72 at a predetermined position, that is, a position rotated by 180 degrees, and stops the rotation. . Note that the board 1 on the rail 12a
6 is fixed from both sides via restraint means (not shown).

The second injection section E has substantially the same configuration as the first injection section C described above. That is, the abutment clamp 78. The injector 8 includes a holding clamp 80, an X-axis arm 82, a Y-axis arm 84, and an injector 86.
6 is connected to a pumping side pipe 88 and a return side pipe 90. Note that the reference numeral 92 indicates a filter, and the reference numeral 94 indicates an exhaust duct. Here, to further explain the resin return path, the return side pipe 46.90 of the re-injection section is connected to the three-way valve 87 via the distributor 50 and filter 92. By means of this three-way valve 87, the returned resin returns to the pump 40 through a branch path 89 and is sent out again during normal times, and returns to the resin tank 36 through a branch path 91 when liquid is drained such as when work is stopped.

Note that the valve 87 is closed when the apparatus is stopped. Branch road 89
A back pressure regulator 93 is provided at the back pressure regulator 93 to ensure the injection pressure from the nozzle by controlling the pressure of the return resin. Further, reference numeral 95 indicates the regulator 4 for the first injection section C.
4 shows a regulator with the same configuration and the same set pressure.

The initial drying section F includes heaters 96, 96.
6 and 96 are installed at appropriate positions on the board 16, and
The coating is configured to initially cure the coated surface by blowing hot air onto it. Also, there is a fan 97.9 on the back of the heater 96°96.
7 is provided to supply fresh air, and warm air is provided to rail 1.
The air is sucked in through a blower (not shown) provided on the side of 2.

The second drying section G is equipped with a belt conveyor 104 composed of rollers 100 and 100 and an endless belt 102 stretched between them, and box-shaped cups 106 are placed on the endless belt 102 as appropriate. The quantity is installed. cough cup 106
is configured to partially house the substrate 16 therein and hold the substrate 16 in an inverted position above the belt conveyor. Note that the reason why the substrate 16 is turned upside down is to reduce the space it occupies in the transport direction. Further, four fans 108a, 108b, 108c, and 108d are arranged in parallel in the upper part of the belt conveyor 104 in the direction of movement thereof, and a heater 1 is arranged below the fan 108a.
10 are provided.

Note that the reference numeral 112 indicates a controller that controls the temperature of the heater 110, and the reference numeral 114 indicates an exhaust duct.Next, the operation of this apparatus will be explained. FIG. 2 is a flowchart of the control unit IO that controls the operation of this apparatus, and FIG. 3 is an explanatory diagram showing the operation of each part. The operation of this device will be explained according to the flow chart in FIG. 2. Step 130
3(a), the board 16 is transported by the transport claws 14 on the rail with its component mounting side facing up.
As shown in FIG. 2, the model is first determined by the light transmission sensor section 18. In this case, three pairs of light receiving elements 18a, 18
The outputs of b and 18c are as shown in FIG. 4, for example, and three types of substrates can be distinguished from the output results. In addition, "0°" in the figure means no output of the light receiving element, "1"
indicates that there is an output. In particular, the output of the light receiving element 18a is also used to determine the presence or absence of the substrate 16.

After the model determination is completed, the substrate 16 is then pushed to the first injection section C by the transport claw 14 in step 132. In the first injection part C, the substrate 16 is held by the abutment clamp 20
．． It is pressed and positioned by the holding clamp 22 from a direction perpendicular to the conveyance path (step 134). In this case, since the conveyance claw is in contact with the rear of the substrate 16, it is fixed in a predetermined position by being pressed from the side by the rods 20c (22c) of both clamps. Note that the protruding pressure of the abutment clamp 20 is set to be relatively large, and that of the restraining clamp 22 is set to be relatively small. The fixed position in this case is determined by the stored program in the control unit 10 according to the board model determined in step 130.

Next, in step 136, molten resin is injected onto the component side of the substrate 16 via the injection mechanism 26. In this case, the acrylic resin and the solvent (toluene or xylene) are mixed in the resin tank 36 at a ratio of 1:1, and the set temperature of the heater 42 is set to 50°C.
Its viscosity is set to 23 to 44 cps, and the injection pressure from the injector 32 is 3 to 5 kg/c+
fl, the molten resin discharged from the cat's eye 32h of the injector 32 is as shown in FIG.
), it is sprayed in atomized form. Compared to conventional air spray methods, this device sprays without the aid of compressed air, so its spray pattern is
As shown in Figure 0, the space is relatively small, so there is no need for mask work, and the thickness of the coating can be made relatively thinner than with conventional film coating methods. It can be applied sufficiently by rolling it around.

In this case, the injection mechanism 26 moves according to the stored program in the control unit 10, and the injector 32 (or nozzle 32g) moves toward the cat's eye 32 as shown in FIG.
While keeping the long axis line of h parallel to the traveling direction of the board 16, it moves in the board traveling direction (or backward direction) while reciprocating in a direction perpendicular to the rail 12, and at the same height set appropriately with respect to the board 16. Then, apply the molten resin from a distance of, for example, 40 mm. Although the height of the nozzle is not controlled in this embodiment, it goes without saying that the height direction may be adjusted. During this airless injection, the moving speed and pitch of the nozzle are
(FIG. 11) is controlled according to the amount of coating per unit area, in other words, according to the effective coating area, and the injection is stopped at the folded portion 120. this is,
This is to avoid overcoating in the movement path, thereby preventing waste of resin or occurrence of liquid dripping. In the present invention, the feed pitch and moving speed of the nozzle are determined by adjusting the nozzle feeding pitch and moving speed at locations where the parts are large in size and height and have a high integration density, or where there are parts such as CPUs, connectors, etc. that are highly important for insulation and moisture-proof leaks. To explain this point in more detail, in the case of the apparatus according to the present invention, as shown in FIG. Slow down the speed (example of movement speed in the same figure), or move the area 16a
The object is temporarily stopped for a period of time corresponding to the effective area (example of movement speed in the figure (■)). As a result, since the spray amount per unit area is varied depending on the area to be coated, a coating with a uniform thickness can be obtained. Moreover, FIG. 14 shows an example of changing the nozzle feed pitch p, and the 13th
The same effect as the method shown in the figure can be obtained. In this case, one of the two methods may be selected, or both methods may be used together. When used together, it is natural that the coating thickness can be controlled more precisely.Next, in step 138 shown in FIG. 2, after confirming the completion of coating on the component side of the board 16, in step 140, both clamps are The rods 20c and 22c are separated from the substrate 16 to release the positioning state. Subsequently, the substrate 16 is transported in the advancing direction by the transport claw 14, transported into the reversing mechanism 60 of the reversing section, and rotated by half a rotation, so that the solder side thereof faces upward (steps 144, 146). FIG. 3(C) shows this state. Since the coating is applied to only the minimum required thickness by airless spraying, the substrate can be turned over without causing liquid blurring.

When the reversing operation is completed, the transport claw 14 is raised as the reversing mechanism 60 is stopped, and the substrate 16 is taken out from within the reversing mechanism 60 and transferred to the second injection section (step 148). At this position, the same operation as in the first injection section described above is performed, and positioning and injection are performed (step 1
50,152). FIG. 3(d) shows this state. Next, when it is confirmed that the solder side coating is completed (Step 1)
54), both clamps 78 and 80 are retracted, the positioning of the substrate 16 is released (step 156), and the substrate 16 is transferred to the initial drying section F (step 158). Note that the application order may be such that the solder side is applied first and the component side is applied last.

In this initial drying section F, as shown in FIG. 3(e), heat drying is performed by drawing in outside air using a fan 97 and a heater 96, and the coated surface is initially cured (step 1).
60).

When this initial drying is completed, the substrate 16 is transferred to the second drying section G by the conveying claw 14, and its tip is inserted into the cup 106 as shown in FIG. The substrate 16 is vertically inverted (step 162).

In this state, first the heater 110 and the fan 108a
The heated air is blown and the substrate is heated and dried. Then three fans 108b.

108c and 108d are sequentially dried at room temperature (step 164). Note that the drying time in this second drying section G is, for example, 13 minutes. As mentioned above, since the coating is applied to only the minimum necessary thickness by airless spraying, liquid does not bleed even if the substrate is held upside down for a long time (13 minutes) with only a short initial drying period. Figure 3 (g), (h)
shows this state. Finally, as shown in FIG. 3(i), the substrate 16 is taken out from the belt conveyor to complete the process (step 166). Note that it is convenient to provide an opening on the side surface of the cup 106 to increase air permeability, as this will facilitate drying.

In the above embodiment, the type of electronic circuit board 16 is determined in the first step.
Although it is performed only in front of the injection part, it is not limited to this, and it may be performed at a position after positioning is completed, and furthermore, it may be performed again after positioning is completed in front of the second injection part E. When resuming work after work has been temporarily interrupted, it is possible to reconfirm the model, and erroneous application can be avoided.

(Effects of the Invention) As described above, the present invention is equipped with an airless injection means for airlessly spraying a resin agent, and is configured to make the feeding pitch of the airless injection means variable. No liquid bleed occurs and coatings of desired thickness can be achieved with minimal resin and solvent consumption. Further, since no liquid drips, the product quality is improved, and the process can be quickly transferred to the coating process on the back side of the substrate, which has the advantage of shortening the working time. It also has the advantage of being able to shorten the drying process line length.

[Brief explanation of the drawing]

Fig. 1 is an explanatory perspective view showing the overall configuration of the film forming apparatus for electronic circuit boards according to the present invention, Fig. 2 is a flow chart showing the control operation of the control unit in the apparatus, and Fig. 3 is the operation of each part. Fig. 4 is an output diagram of the light transmission sensor showing the model discrimination operation, Fig. 5 is an explanatory cross-sectional view showing the structure of the abutment clamp (holding clamp), and Fig. 6 shows the outline of the injection mechanism. FIG. 7 is an explanatory sectional view of the X-axis (Y-axis) arm, FIG. 8 is an explanatory sectional view of the injector, FIG. 9 is a front view of the nozzle of the injector, and FIG. 1O is the injection pattern. FIG. 11 is an explanatory diagram showing the nozzle movement locus, FIG. 12 is an explanatory perspective view showing details of the reversing mechanism, FIG. 13 is an explanatory diagram showing an example of change in nozzle movement speed, and FIG. An explanatory perspective view showing an example of change in the nozzle feed pitch and FIGS. 15(a), (b), and (c) are explanatory diagrams showing airless injection in the present invention in comparison with the prior art. 10... Control unit, 12... Rail, 14...
- Transport claw, 16... Electronic circuit board, 18... Light transmission sensor section, 26... Injection mechanism, 32... Injector, 32g... Nozzle, 36... Resin tank, 60
...Reversing mechanism, 86... Injector, 96...
Heater, 104... Belt conveyor, 106... Cup, 108a, 108b, 108c, toaa...
Fan, 110... Heater, A... Transport section, B...
・Model discrimination section, C...first injection section, D...reversal section,
E...Second injection section, F...Initial drying section, G...Second drying section Figure 6 Procedure amendment 1 issue) April 14, 1988

Claims (1)

[Claims] a positioning means for positioning an electronic circuit board at a predetermined position; an airless injection means for airlessly spraying a resin agent onto the positioned electronic circuit board; a drying means for drying the electronic circuit board after airless injection; An apparatus for forming a film on an electronic circuit board, characterized in that the apparatus comprises a driving means for moving an airless injection means in the length direction and width direction of the electronic circuit board, and a feeding pitch of the airless injection means is variable.