JPH0568922A - Liquid resist coating apparatus and method for printed wiring board - Google Patents

Abstract

PURPOSE:To uniformly apply resin coating to both surfaces of a board in sufficient thickness, in a system having two or more pairs of coating rollers, by specifying the rubber hardness of the coating rollers and the viscosity of the liquid resist supplied to the respective roller pairs. CONSTITUTION:Ink tanks 1-3, 2-3 are provided to the lower parts of first and second roller devices 1,2 and the lower parts of lower rubber rollers 1-2, 2-2 are immersed in the ink tanks 1-3, 2-3 and a necessary amount of a liquid resist is supplied to upper rubber rollers 1-1, 2-1 from the ink tanks 1-3, 2-3 by the operation of quantitative pumps 1-5, 2-5 through nozzles 1-6, 2-6. A roller device 3 has upper and lower rollers 3-1, 3-2 in the same way but ones with the highest rubber hardness are used as said rollers 3-1, 3-2 and this roller device 3 uses a resist having the highest viscosity as compared with the other roller devices 1,2. A resist having the lowest viscosity is used in the first roller device consisting of rollers having the lowest rubber hardness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a printed wiring board,
More specifically, the present invention relates to a method and an apparatus for coating a liquid resist for a solder mask, and more specifically, both sides of a substrate can be simultaneously coated with a sufficient thickness, and there is no scratch or bubble (skip) in the coating film. The present invention relates to a coating apparatus and a coating method that enable more efficient coating work.

[0002]

2. Description of the Related Art Conventionally, the following method has been generally used for coating a liquid resist for a solder mask on a printed wiring board (hereinafter simply referred to as a board). (1) Spray method (2) Screen printing method (3) Roller coating method (4) Dry film method However, in the spray method of (1), the loss of resist ink is large. The application amount is uneven. In the screen printing method of (2), uniform coating is insufficient on a high-density circuit board. Also, it is usually a coating on each side of the substrate. Therefore, it is impossible in terms of efficiency and quality. In the dry film method of (4), the adhesion between the substrate and the film and the sticking device are large scale. Further, the dry film itself is expensive. Etc. have their respective drawbacks.

The roller coating method (3) is
Although it has been used in the past because it can be relatively easily performed, in the method that has been conventionally performed, it is difficult to coat evenly to a predetermined thickness because the coating is performed using only a pair of roller devices. is there.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the drawbacks of the conventional method and apparatus for coating a liquid resist for a solder mask of a substrate, and in a roller coating method capable of simplifying the apparatus, both sides of the substrate are covered. At the same time, another object of the present invention is to provide a liquid resist coating apparatus for a printed wiring board and a coating method thereof, which enables a coating operation to be performed with a sufficient thickness evenly, without causing the coating film to be scratched and without bubbles (skips).

[0005]

According to the present invention, there is provided a coating apparatus having a plurality of pairs of coating rollers, wherein the plurality of pairs of coating rollers have a soft rubber hardness in the direction of travel of the substrate. It is provided by gradually changing to a hard one, and the viscosity of the liquid resist supplied to each pair of coating rollers is changed stepwise from low viscosity to high viscosity in the traveling direction of the substrate. A liquid resist coating apparatus for a printed wiring board is provided.

Further, according to the present invention, a plurality of pairs of coating rollers are provided, and the plurality of pairs of coating rollers have a rubber hardness of a roller from a soft one to a harder one in the traveling direction of the substrate. To a coating device which is arranged while being changed stepwise, and which supplies the liquid resist by changing the viscosity stepwise from a low-viscosity one to a high-viscosity one in the order of the traveling direction of the substrate to each pair of coating rollers, Provided is a method for coating a liquid resist for a printed wiring board, which comprises coating the substrate surface with the liquid resist a plurality of times through the substrate.

[0007]

In the coating apparatus of the present invention, a plurality of pairs of coating rollers are arranged in the advancing direction of the substrate by gradually changing the rubber hardness of the rollers from soft to hard. The liquid resist supplied to each pair of coating rollers is characterized in that the viscosity is changed step by step from low viscosity to high viscosity in the advancing direction of the substrate. Each pair of coating rollers is supplied with liquid resist not only on one side but also on the pair (both) rollers, and the amount of liquid resist deposited on the rollers is adjusted so that the substrate passes through the pair of coating rollers. By doing so, it is possible to coat both surfaces with the liquid resist at the same time. Further, since a plurality of pairs of coating rollers are provided, it is possible to continuously coat the liquid resist on the substrate a plurality of times in one stroke.

In the printed wiring board, a step is formed between the board surface and the conductor portion wired. In the coating apparatus and the coating method according to the present invention, the substrate is coated with the liquid resist having the lowest viscosity by the first pair of coating rollers having the first rubber having a soft rubber hardness and the cushioning property. Since the liquid resist has a low viscosity, the liquid resist has good wettability, spreadability and coating properties on the substrate surface. In addition, the rubber hardness of the roller is soft and cushioning, so it adapts to the step on the substrate surface, so the liquid resist coating on the substrate surface is evenly coated on the step portion of the substrate surface. Air bubbles (skip)
Does not occur.

The rubber hardness of the coating roller of the next pair is slightly harder than that of the coating roller of the first pair, and the viscosity of the liquid resist to be supplied is slightly high. , The surface of the substrate has been improved by the first coating to make it smoother, which makes it easier to coat, and
Unevenness, bubbles (skips), etc. are not corrected, and the coating thickness becomes thicker, and uniform coating becomes possible. The rubber hardness of the coating roller is harder than that of the first coating roller.
It is useful for correcting and eliminating scratches, unevenness, and bubbles (skips) in the second coating film.

The rubber hardness of the roller of the last pair of coating rollers in the advancing direction of the substrate is the hardest, and the viscosity of the liquid resist supplied is the highest. With this final pair of coating rollers, the substrate is coated on both sides with the most viscous liquid resist. The surface of the substrate is further improved in level difference and is gentle and the base coating film is uniform, so that it is possible to uniformly coat the substrate with a large coating thickness. Even if the coating on the surface of the substrate has had scratches, unevenness, or air bubbles (skips) in the past, it can be eliminated by this last coating, and a coating with a uniform and desired coating thickness can be obtained. Can be coated.

Thus, by using a plurality of pairs of coating rollers in which the rubber hardness of the rollers is changed step by step from soft to hard, the viscosity of liquid resist is gradually changed from low viscosity to high viscosity. By applying the liquid resist continuously and coating the liquid resist on the substrate surface a plurality of times continuously, it is possible to obtain a uniform and desired coating thickness without causing scratches, unevenness or bubbles (skips) in the coating film. A liquid resist can be coated.

Each pair of coating rollers of the coating apparatus of the present invention (upper and lower pairs in the embodiment)
Although the liquid resist is supplied to the both sides to simultaneously coat both sides of the substrate, it is of course possible to supply the liquid resist to only one of the pair of rollers to coat the one side.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The coating apparatus of the present invention will be described with reference to the drawings. The coating apparatus of the present invention is
As shown in FIG. 1, it has three sets of coating roller devices (hereinafter simply referred to as roller devices) 1, 2, and 3. Each roller device has an upper rubber roller 1-1, 2-1, 3-1 and a lower rubber roller 1-, respectively.
2, 2-2, 3-2 are provided as a pair, and each is rotationally driven in the arrow direction by a known method (not shown). In this embodiment, there are three sets of roller devices as shown in FIG. 1 as described above, but if possible, two sets,
If necessary, four sets of roller devices can be used.

The first and second roller devices 1 and 2 are
Ink tanks 1-3 and 2-3 are provided below the liquid tank, and a liquid resist (not shown) is supplied thereto by a suitable amount from other sources.

The lower parts of the lower rubber rollers 1-2 and 2-2 are immersed in the ink tanks 1-3 and 2-3, and the liquid resist is transferred upward by the rotation thereof. On the other hand, ink tank 1
-3 and 2-3 are provided with pipes 1-4 and 2-4, and metering pumps 1-5 and 2-provided in the middle of the pipes.
5, the required amount of liquid resist is also supplied to the respective upper rubber rollers 1-1 and 2-1 via the nozzles 1-6 and 2-6 whose supply amount can be adjusted.

Upper rubber rollers 1-1 and 2-1 and lower rubber rollers 1-2 and 2-of the roller devices 1 and 2 are used.
2 has doctors 1-7 and 2-7, and the amount of liquid resist adhered to each rubber roller is adjusted by adjusting the degree of pressure bonding.

The roller device 3 has an upper rubber roller 3-1 and a lower rubber roller 3-2 like the others, but as will be described later, the resist having the highest viscosity as compared with the other roller devices. Use liquid. Further, for the purpose of adjusting the coating amount and finally adjusting the uniformity, a resist supply roller 3-3 for accurately and indirectly supplying a liquid resist is provided at each of the upper and lower sides, and an ink tank 3-4 is provided therein. Have

The resist supply roller 3-3 accurately adjusts the amount of liquid resist adhered to the upper rubber roller 3-1 and the lower rubber roller 3-2 by adjusting the degree of pressure bonding. Also, this resist supply roller 3-
3 is usually made of stainless steel or hard resin.

In the above-mentioned device, in the first roller device 1, the upper rubber roller 1-1 and the lower rubber roller 1-2 have a rubber hardness (according to JIS K 6301) of Hs25 to Hs50, which is soft and cushioning. The inside of the roller rubber layer may be sponge-shaped. The liquid resist used for this has the lowest viscosity as compared with the other roller devices 2 and 3. This prevents bubbles (skips) 5b that are likely to occur at the step between the substrate 5 and the conductor portion 5a as shown in FIG. 3, and applies the liquid resist evenly over the entire surface of the substrate.

In the second roller device 2, the rubber hardness of the upper rubber roller 2-1 and the lower rubber roller 2-2 is set to an intermediate hardness of about Hs40 to Hs70, and the viscosity of the liquid resist used for this is standard. Have an intermediate viscosity. As a result, uneven coating by the first roller device,
Corrects blurring, etc., and applies even coating without uneven coating, blurring, or air bubbles.

In the third roller device 3, each of the upper rubber roller 3-1 and the lower rubber roller 3-2 has a rubber hardness of Hs60 or more, and the viscosity of the liquid resist used therefor is also different from that of the other roller devices. It has the highest viscosity compared to. As a result, finish coating is performed so as to correct coating unevenness, scratches and the like caused by the first and second roller devices and to ensure a prescribed coating thickness evenly.

The viscosity of the liquid resist used in each of the above roller devices 1, 2 and 3 should be determined depending on the operating conditions depending on the atmospheric conditions, the coating speed, the prescribed coating amount, etc. Then, in the method of the present invention, it is necessary that the roller devices 1, 2 and 3 are sequentially made to have a low viscosity, a medium viscosity and a high viscosity.

In FIG. 1, the substrates 5 are sequentially supplied one by one on the table 4 on the left side of the drawing, and while the liquid resist is coated on both surfaces by the above roller devices 1, 2 and 3, the substrate 5 is sequentially moved in the arrow direction. Is passed and transferred to. During passage, conical guide rollers 6 are arranged at appropriate intervals between the roller devices 1, 2 and 3 to support both edges of the substrate 5 as shown in FIG. The guide roller 6 has a structure capable of sliding in the arrow direction of FIG. 2 according to the width of the substrate 5. Therefore, the substrate 5 is supported and transported by the guide roller 6 without touching the coating surface.

The substrate 5 that has passed through the final roller device 3.
Although not shown, the sheets are received one by one by a robot hand or the like, inserted into the rack 7, and transferred to the next step such as drying.

If necessary, it is possible to provide an intermediate drying facility between the roller devices 1 and 2 or between the roller devices 2 and 3 or to provide a final drying facility at the rear part of the roller device 3.

[0026]

According to the coating apparatus and the coating method of the present invention, the low-viscosity liquid resist is applied to the both surfaces of the substrate by the pair of coating rollers having soft rubber hardness, and then the rubber hardness of the rollers becomes higher. You can apply the most viscous liquid resist with a pair of coating rollers that are the hardest pair of rollers and finally apply the most viscous liquid resist with the pair of coating rollers. It is carried out continuously in one step, and the liquid resist is applied to both sides of the substrate at the same time without any defects such as scratches, unevenness or bubbles (skipping) of the coating film, and the coating thickness is sufficiently thick and even to the desired thickness. Can be coated on. A good quality coating can be obtained in one step, the coating work can be performed efficiently, and labor and cost can be significantly reduced.

[0027]

[Brief description of drawings]

FIG. 1 is a side view showing an example of a coating apparatus of the present invention.

FIG. 2 is an explanatory view of a guide roller in the coating apparatus of the present invention.

FIG. 3 is a partial cross-sectional view of an example of a printed wiring board used in the present invention.

[Explanation of symbols]

 1 1st coating roller apparatus 2 2nd coating roller apparatus 3 3rd coating roller apparatus 1-1 Upper rubber roller 2-1 Upper rubber roller 3-1 Upper rubber roller 1-2 Lower rubber roller 2-2 Lower rubber roller 3- 2 Lower rubber roller 1-3 Ink tank 2-3 Ink tank 1-4 Piping 2-4 Piping 1-5 Metering pump 2-5 Metering pump 1-6 Nozzle 2-6 Nozzle 1-7 Doctor 2-7 Doctor 3- 3 Resist Supply Roller 3-4 Ink Tank 4 Table 5 Printed Wiring Substrate 5a Printed Wiring Substrate 5b Conductor 5b Air Bubble (Skip) 5c Resist Coating Layer 6 Guide Roller 7 Rack

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[Procedure amendment]

[Submission date] September 24, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief explanation of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a side view showing an example of a coating apparatus of the present invention.

FIG. 2 is an explanatory view of a guide roller in the coating apparatus of the present invention.

FIG. 3 is a partial cross-sectional view of an example of a printed wiring board used in the present invention.

[Description of Reference Signs] 1 first coating roller device 2 2nd coating roller device 3 3rd coating roller device 1-1 upper rubber roller 2-1 upper rubber roller 3-1 upper rubber roller 1-2 lower rubber roller 2-2 Lower rubber roller 3-2 Lower rubber roller 1-3 Ink tank 2-3 Ink tank 1-4 Piping 2-4 Piping 1-5 Metering pump 2-5 Metering pump 1-6 Nozzle 2-6 Nozzle 1-7 Doctor 2 -7 Doctor 3-3 Resist supply roller 3-4 Ink tank 4 Table 5 Printed wiring board 5a Conductor part 5b Bubbles (skip) 5c Resist coating layer 6 Guide roller 7 Rack

Claims (2)

[Claims] 1. A coating apparatus having a plurality of pairs of coating rollers, wherein the plurality of pairs of coating rollers have a rubber hardness stepwise from a soft one to a hard one in a traveling direction of a substrate. It is characterized in that it is provided by changing and the viscosity of the liquid resist supplied to each pair of coating rollers is gradually changed from low viscosity to high viscosity in the traveling direction of the substrate. Liquid resist coating equipment for printed wiring boards. 2. A plurality of pairs of coating rollers are provided, and the plurality of pairs of coating rollers gradually change the rubber hardness of the rollers from a soft one to a hard one in order in the traveling direction of the substrate. Through the substrate to the coating device that supplies the liquid resist by changing the viscosity stepwise from low viscosity to high viscosity in order of the direction of travel of the substrate to each pair of coating rollers. A method for coating a liquid resist for a printed wiring board, characterized in that the liquid resist is coated on the substrate a plurality of times.