JPS614571A - Drip cup of coating solution - Google Patents

Abstract

PURPOSE:To obtain uniform distribution of drips irrespective of the liquid level in a cup by arranging drips holes, which are provided on the bottom surface of the drip cut contg. a coating soln., in two files, specifying the arrangement, and protruding the holes to the outside of the drip cup. CONSTITUTION:A drip cup 7 is immersed in a coating soln. vessel to scoop up the soln., and raised up to drip the soln. onto a printed board. The drip hole 8 on the bottom surface of the cup is protruded to the outside of the cup. The drip holes 8 are arranged in two files, and the drip holes 8 in one file are arranged at a position intermediate between the drip holes 8 in the other file. Consequently, linear coating soln. drips are always dropped on the board at regular intervals irrespective of the liquid level in the cup, and a uniform coated film is formed without generating any unevenness.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a coating method for forming a substantially uniform coating liquid film on an article having a relatively flat surface such as a printed circuit board. This invention relates to a dripping cup that drops a linear drop of coating liquid to form a coating film on an object to be coated.

[Prior Art] Generally, in the process of assembling a printed circuit board, after soldering (=t
Or coating the surface of the printed circuit board? 1RI
I! ,! has been formed and all assembly processes of the printed circuit board have been completed.

Common methods for coating articles of this scale include the above-mentioned dipping method and spraying method. The technique described in JP-A-58-159862 relates to the formation of a coating film by dipping. As described in the above-mentioned publication, in order to form a coating film on the surface of an article by immersing it in a coating liquid, the dipping speed, that is, the vertical pull-up time and the time, are determined depending on the viscosity of the coating liquid and the thickness of the film to be formed. The coating process is carried out by arbitrarily setting the relationship between. In the method of spraying silicone paint, etc., the coating process is carried out by arbitrarily setting the transport speed and spraying distance of the article.

[Problems to be solved by the invention] However, in the immersion method, for example, when attaching connectors, relays, and buzzers to printed circuit boards, etc., they are also immersed in the coating cavity, so they are electrically damaged. If the connection part is insulated by a coating or if the mechanical vibration sounding part is covered with a coating, electrical interference will occur.

Similar problems occur in the spraying method, and since the spraying method uses a large amount of diluting solvent, there are problems such as air pollution and a large amount of coating liquid being scattered.

1′″1・°−7″″j l! ! j (7) (”j
% @ @ 5 ``if45n'' Printed circuit boards, etc., in which ``if45 n'' is inserted have been coated by methods such as □ brushing or liquid flow, but both methods require manual work. ,
There are problems such as the coating liquid adhering to other materials during transfer to the drying process.Furthermore, the former method using a brush may cause uneven coating, or the coating liquid may leak onto connectors, relays, or buzzers during the application process. In addition, in the latter coating method using a liquid stream, it may not be possible to form a specific liquid stream due to turbulence in the flow rate of the jetted or dropped liquid stream, the viscosity of the coating liquid, surface tension, etc. Especially when dripping from a dripping cup,
The initial flow rate of the liquid flow is different from the flow rate at the end, and the usage conditions are not necessarily favorable.

Therefore, the present invention provides a coating liquid applicator for coating a coating liquid by dropping, in which a liquid flow dripping from a dripping cup always forms a predetermined linear dripping coating liquid flow, regardless of the liquid level in the dripping cup. The task is to provide the cup.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a coating liquid applicator for applying a coating liquid dropwise, in which the dripping holes on the bottom of the dripping cup are connected to other dripping holes in the dripping hole row. The drip cup is located in the middle between the rows of drip holes, and has a structure that protrudes from the outside of the drip cup.

[Function] According to the above configuration, by providing the dripping hole of the dripping cup so as to protrude outward, the falling direction of the coating liquid dripping linearly does not change due to the viscosity of the coating liquid covering the bottom surface of the dripping cup. Moreover, even if slight fluctuations occur, the intervals between the dripping holes are widened so that they do not come into contact with and merge with the coating liquid dripping in a linear manner, and
Since the positional intervals are determined so that the dropped coating liquid is distributed uniformly, a uniform coating film can be formed on a predetermined surface.

``Example'' Next, an example of the coating liquid application apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a flowchart of each process showing a coating liquid applying apparatus according to an embodiment of the present invention. In the figure, 10 is an attachment process, 20 is a first coating process, 30 is an inversion process, 40 is a second coating process, 50 is a liquid removal process, 60 is a drying process, and 70 is a removal process.

2 is a perspective view showing the coating process shown in FIG. 1, and FIG. 3 is a bottom view of the dripping cup 7.

First, the constituent parts of this example will be explained with reference to a perspective view showing the coating process in Fig. 2 and a bottom view of the dripping cup in Fig. 3.
C.Explain.

Both ends of the printing substrates Pi, i are held by a holder 3 which constitutes a transfer means that moves back and forth on a guide rail 4 by a chain 2.

The dripping cup 7 normally settles in the coating liquid bath 5 when the printed circuit board 1 is not being transported (and as the printed circuit board 1 approaches the dripping cup 7,
Pump up the coating liquid 6 into the dripping cup 7 and rise to the top. 8□0. −
ga9a□5o.

- It settles in the liquid tank 5. As shown in the bottom surface of the dripping cup 7 in FIG. 3, a plurality of dripping holes 8 are bored in the bottom of the dripping cup 7.
is the width corrected based on the width of the coating surface necessary for the object to be coated, such as the printed circuit board 1, based on the falling speed, viscosity, surface tension, etc. of the coating liquid. The distance 1lllla between the drip holes in the rows of drip holes 8 and the distance between the drip holes in the rows and the row spacing L2 are the distances required for the coating liquid to drip linearly, and similarly to the former, the falling speed of the coating liquid and It is calculated based on viscosity, surface tension, etc.

The dripping hole 8 further determines the flow direction because the linear dripping coating liquid 6a flowing out from the dripping hole 8 is not affected by the adhesive force with the coating liquid covering the dripping cup 7. In order to do this, either the hole is punched out from within the drip cup 7 and the punched piece is exposed to the outside, or a drop guide tube is joined to the drip hole 8 of the drip cup 7.

Especially when using a punched hole, the production of the dripping cup 7 involves pressing.
It is inexpensive because it can be done by hand. If the falling guide tube is joined, the length and diameter of the tube can be selected arbitrarily, and the viscosity of the coating liquid and the flow velocity range of the drip hole can be widened.

Further, the coating M6 in the coating liquid tank 5 is always set at a constant coating liquid concentration and liquid level by mixing the coating liquid and a diluting solvent by an external coating liquid concentration adjusting device (not shown). In addition, 1n in the figure indicates the supply from the coating liquid concentration adjusting device.
ut means discharge to the coating liquid concentration adjusting device.

Next, an embodiment of the coating liquid applying apparatus will be described in detail according to the flowchart of each process in FIG. 1 and using explanatory diagrams of each process in FIGS. 4 to 9.

In the mounting process 10, as shown in the explanatory diagram of FIG. 4, both ends of the printed circuit board 1 are mounted diagonally to the holding parts (not shown) of the holder 3 so that the soldered surfaces are located on the top surface. Ru.

The inclination of the printed circuit board 1 is determined by the falling speed of the coating liquid, viscosity, surface tension, conveyance speed of the printed circuit board, etc.

The printing plate 1 held by the holder 3 is conveyed toward the dripping cup 7 and enters the first coating step 20 . When the conveyance of the printed circuit board 1 is started, the dripping cup 7 starts to rise, and rises above the level of the printed circuit board 1 to be conveyed by the time the holder 3 comes under it. The coating liquid 6 in the dripping cup 7 becomes a linear dripping coating liquid 6a and drips from the dripping hole 8.

In the first coating step 20, the holder 3t is moved along the guide rail 4, and as shown in the explanatory diagram of the coating state in FIG. The droplet collision speed is a vector combination of the falling speed of the linearly dropped coating liquid 6a and the conveyance speed of the printed circuit board 1, and is determined by the viscosity of the coating liquid and the like.

Generally, when applying the coating liquid to the soldering surface, the linear dripping colting liquid 6a is dripped and collided without reducing the conveyance speed of the printed circuit board 1, and the linear dripping coating liquid 6a is applied to the four sides of the soldering surface. By scattering, the thickness of the coating can be made more uniform, and a wider area can be coated.

The printed circuit board 1 whose soldering surface has been coated with the linear drop coating liquid 6a enters an inversion step 30. That is, the holder 3 is conveyed by the holder 3, and the holder 3 is turned upside down so as not to come off from the coating liquid tank 50, and then, as shown in FIG. 6, the printed circuit board is turned over. The reversal angle θ is determined by the type and color of the mounted electronic component, the falling speed of the coating liquid mentioned in 1, viscosity, surface tension, etc.

In addition, holder 3 is reversed! (For structure 11, guide rail 4
Although the guide rail 4 is reversed as the moving direction of the guide rail 4 is changed, a reversing mechanism that is independent of the moving direction of the guide rail 4 may be used.

When the reversal of the printed circuit board 1 is completed, the transport direction of the printed circuit board 1 is changed, and the dripping cup 7 of the printed circuit board 1 is moved again.
Then, a linear drop 1 was applied to the electronic component mounting surface of the printed circuit board 1 shown in the explanatory view of FIG. - 9 hours, 6
8-ee, □~□eng. □, enters the 40s. At this time, it is preferable to transport the printed circuit board 1 at a slow speed or stop it as necessary to allow the coating liquid 6a to fall onto the electronic component mounting surface. That is, on the surface of the printed circuit board 1 on which electronic components are mounted, it is necessary to suppress the scattering of the coating liquid 6 and apply it only to a predetermined area. It reduces speed. Then, place the printed circuit board 1 at any location.
By stopping the conveyance of C, the coating liquid can be sufficiently distributed to the feet of C and the like.

After finishing applying the coating liquid to the electronic component mounting surface of the printed circuit board 1, the next liquid draining step 50 begins. As shown in the explanatory diagram of the liquid draining step 1 in FIG. 8, once the printed circuit board 1 is conveyed to a position away from under the dripping cup 7, it is temporarily stopped, and there, the coating is applied to both sides of the printed circuit board 1. Drain any excess liquid. This stop position is the coating liquid 15 where the excess coating liquid can be recovered.

It is desirable to be located at the top of the Of course, it may be further away than that, but in that case, the excess 11
-5 It would be better to make it possible to collect the coating liquid into the coating liquid tank 5.

The printed circuit board 1 that has completed the liquid draining step 50 is further transported and enters a drying step 60. As shown in FIG. 9, which is an explanatory diagram of 1-drying step, the printed circuit board 1 is transported to the vicinity of where the drying air is blown. In the drying step 60, the printed circuit board 1
The coating liquid coated on the printed circuit board 1 is dried by blowing out dry air from the bottom of the board.

At this time, since the ejection port is only at the lower part, by alternately inverting the surface of the printed circuit board 1 at an angle δ, it is possible to dry both sides at the same time. The printed circuit board 1 is reversed by changing the direction of movement of the holder 3 within a minute range, but as described above, even if the reverse operation of the printed circuit board 1 is performed by a mechanism with a separate holding part, good. According to the above-mentioned alternating reversal, not only double-sided drying but also uniformity of the coating film can be expected. Of course, the same effect can be obtained when the dry air blowout is disposed at a location other than the lower part, and the same effect can be obtained for heat sources other than dry air such as secondary copper heat. The angle δ at which the surface of the printed circuit board 1 is alternately reversed may be set to be the same as the reversal angle θ at which the printed circuit board 1 is reversed in the reversing step 30.

In addition, in this embodiment, the printed circuit board 1 is alternately reversed to create an air flow on the surface of the printed circuit board, so that it can be efficiently dried simply by using dry air as a drying means, and in particular, temperature rise is averse to Suitable for drying electronic parts.

Furthermore, in devices equipped with this type of reversing mechanism, since the coating film on the printed circuit board 1 is dried using drying air from only one side, toluene, xylene, etc. contained in the coating liquid are removed by the air. The toluene, xylene, etc. can be discharged from an exhaust path that is blocked from the outside air and can be flowed in the opposite direction to the outside air, so there is no risk of harm to the health of the workers.

After the drying process 60 is completed, the extraction process 70 begins.

In the take-out step 70, the coated printed circuit board 1 is taken out and packed into a shipping box or the like, or transported to the next production line.

After the removal process 70 is completed, the first installation process 10 is started.

According to this embodiment, the mounting process 10 includes attaching the printed circuit board 1 to the transfer holder 3 that transports the printed circuit board 1 along the guide rail 4, and the step of dropping the coating liquid 6 onto the printed circuit board 1 while normally in a coating liquid. The first coating step 20 in which the coating liquid 6 is dripped only on the specified location on the surface of the printed circuit board 1, and the printed circuit board 1 that has completed the coating step on the negative side, is reversed. A second coating step 40 for the other side of the printed circuit board 1, a liquid draining step 50 for draining excess coating liquid from the printed circuit board, a drying step 60, and a removal step 70. In the coating liquid drop applicator, the drip cup 7 sinks into the coating liquid tank 5 to draw up the coating liquid 6, and also rises above the coating liquid tank 5 to drip onto the printed circuit board 1. 8 protruding from the outside of the dripping cup 7, the falling method of the coating liquid dripping in a linear manner does not change due to the viscosity of the coating liquid 6 covering the bottom surface of the dripping cup 7, and even if Even if slight fluctuations occur, the intervals between the drip holes are set large so that the droplets can fall without merging with the linearly dripped coating liquid 6a, and the positional intervals are set so that the dropped coating liquid is evenly distributed. Therefore, regardless of the coating liquid level in the dripping cup 7, that is, regardless of the dripping speed flowing out from the dripping hole 8, the linearly dripped coating liquid 6a from the dripping hole 8 always prints the coated object at a predetermined interval. The coating liquid falls onto the substrate 1, and the coating liquid is distributed uniformly, making it possible to eliminate unevenness of the coating film.

Furthermore, in this embodiment, since the holder 3 that transfers the printed circuit board 1 is reciprocated in the reversing step 30,
The coating device for the coating liquid of this embodiment can be made smaller.

And - This example uses 0-din from the dripping cup.
Since the coating liquid is applied onto the printed circuit board by dropping the coating liquid, the coating liquid is used without turning into fine particles, so there is no fear of scattering of the coating liquid or contamination.

As described above, in the present invention, the drip holes in the bottom of the drip cup are located in the middle between the drip holes in another drip hole row, and protrude from the outside of the drip cup. Therefore, the present invention is not limited to the above-mentioned embodiments as long as it is a coating liquid application device that drips and applies a coating liquid using a dripping cup.

For example, the coating liquid drop coating apparatus according to the embodiment of the present invention shown in FIG. 1 can be modified as follows.

That is, in the first application step 20 and the second application step 40, the linear dripping coating liquid 6a was applied with a single dripping cup 7, but the coating liquid 6a is applied from the same or the same dripping liquid 111 to the coating liquid 6a. With two drip cups that draw
The coating width of the first coating process 20 and the coating width of the second coating 1 culm 40 may be changed. In this case, since the linear handle coating liquid will be applied to the printed circuit board 1 using different dripping cups, the coating area between the solder surface and the electronic component mounting surface of the printed circuit board 1 will be changed. can do.

It goes without saying that other objects can be used, although the coating has its characteristics, particularly for coating printed circuit boards.

[Effects of the Invention] As described above, the dripping cup for the liquid of the present invention has the following effects:
The drip holes on the bottom of the drip cup are provided to protrude outside the drip cup, and the drip holes in one drip hole row are positioned midway between the drip holes in other drip hole rows. The coating liquid drips in a linear manner depending on the viscosity of the coating liquid covering the bottom of the dripping cup] - A coating that does not change the falling direction of the coating liquid and even if there is a slight fluctuation, it drips in another linear shape. The intervals between the drip holes are set so that they do not come into contact with the liquid and merge, so the
This has the effect that the coating liquid is uniformly applied to the object to be coated, and uneven coating does not occur.

[Brief explanation of the drawing]

Fig. 1 is a flowchart of each process showing a coating liquid application device according to an embodiment of the present invention, Fig. 2 is a perspective view of the culm shown in Fig. 1, and Fig. 3 is a bottom view of the droplet F cup. Figure 4 is an explanatory diagram of the installation process, Figure 5 is an explanatory diagram of the first application],
Fig. 6 is an explanatory diagram of the reversing process, Fig. 7 is an explanatory diagram of the second coating process, Fig. 8 is an explanatory diagram of the liquid draining process, and Fig. 9 is an explanatory diagram of the drying process. -C1 1... Printed circuit board, 3... Holder, 5
... = 1-ding liquid tank, 6... coaching liquid, 7... dripping cup, 8... dripping hole,
a... Distance between dripping hole phase H, 10... Take (=j
I culm, 20... First coating process, 30... Reversing process, 40... Second coating process, 50... Liquid draining process, 60... Drying process, 70... Taking out process, It is. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts.

Claims (5)

[Claims] (1) In a coating liquid applicator that drips and applies a coating liquid using a dripping cup, the dripping hole on the bottom of the dripping cup is provided to protrude outside the dripping cup, and the dripping hole in the dripping hole row is connected to another dripping hole row. A coating liquid dripping cup, characterized in that the coating liquid dripping cup is arranged to be located midway between the dripping holes. (2) The coating liquid dripping cup according to claim 1, wherein the dripping holes are arranged with equal distances between the dripping holes in each row and between the dripping holes in the rows. (3) The coating liquid dripping cup according to claim 1 or 2, wherein the dripping hole is a punched hole. (4) The coating liquid dripping cup according to claim 1 or 2, wherein the dripping hole is formed by joining a drop guide cylinder. (5) The coating liquid application device includes a mounting process in which the printed circuit board is attached to a transfer holder for transporting the printed circuit board, and a coating liquid is dripped onto the attached printed circuit board from a dripping cup onto a specific surface of the printed circuit board. a first application step of applying a coating liquid; an inversion step of reversing the surface of the printed circuit board that has completed the first application step on the specific surface; and dripping the coating liquid from a dripping cup onto the other surface of the printed circuit board. The coating process consists of a second application process in which the coating liquid is applied to the printed circuit board using a drying method, a liquid draining process in which excess coating liquid is drained from the printed circuit board, a drying process for the drained printed circuit board, and a process for taking out the printed circuit board after drying. A coating liquid dripping cup according to any one of claims 1 to 4, characterized in that: