JPH07212014A - Clogging removing method for substrate through hole - Google Patents

Abstract

PURPOSE:To completely remove the clogging of a through hole without any restriction on the coating of a resist material in an optimum state CONSTITUTION:The surface of a substrate 2, having a through hole 4, is coated with resist material 1. Then, before the resist material 1 is completely dried up, a gas stream is suddenly generated in the through hole 4. The resist material 1, with which the through hole is blocked, is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of preventing through holes formed in a substrate from being left blocked by a resist material applied to the surface of the substrate in the process of manufacturing a circuit substrate.

[0002]

2. Description of the Related Art A photosensitive photoresist material is applied to the surface of a substrate to form a solder mask on the substrate by a photographic method. As a coating method, a screen printing method, a roll coater coating method, a spinner coating method, a spray coating method, a curtain coater coating method and the like are known.

However, no matter which coating method is adopted, various problems occur due to the resist material blocking the through holes of the substrate.

For example, if the resist material applied to both surfaces of the substrate is heated and dried while blocking both ends of the through hole, the pressure inside the through hole rises and the resist material bursts. Further, when one side of the through hole is blocked and the other side is coated, there are some areas where the through hole is not blocked, and only one side is blocked. In the case as described above, the treatment liquid or the like is difficult to be washed in the subsequent step, and the residual marks left in the through holes may chemically change over time, resulting in disconnection in the through holes. Further, when the resist material is clogged in the through hole, it cannot be completely removed during development, and the resist in the through hole remains.

Therefore, several proposals have been made to prevent the through holes from being blocked by the resist material. For example, in one conventional method, it has been proposed that a solder resist material having a specific viscosity range is thinly applied at a controlled drop speed by a curtain coater to minimize the invasion of the resist material into the through hole (Japanese Patent Application Laid-Open No. 2000-242242). JP-A-54-82073). However, in order to sufficiently cover the surface of the substrate on which the circuit is formed and has irregularities with the solder resist material, it is necessary to thicken the coating film to some extent to prevent defective coating. On the other hand, if the coating operation is repeated several times in order to thicken the coating film, the efficiency of the curtain coater will be meaningless.

[0006] In another conventional method, a photosensitive solution having a specific composition excellent in developability and solubility is used as a solder resist to remove the resist material flowing into the through holes during coating by a curtain coater during development. It has been proposed to make it easier (Japanese Patent Laid-Open No. 63-
80594). However, in this method, the composition of the resist material used is restricted in order to reliably remove the resist material.

[0007]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to reliably remove the clogging of through holes without any restrictions on the application of the resist material in an ideal state.

[0008]

In order to solve the above-mentioned problems, according to the present invention, after the resist material is applied to the surface of the substrate having through holes in the circuit board manufacturing process, the resist material is completely dried. There is provided a method for removing clogging of a through hole of a substrate, which is characterized in that a rapid gas flow is previously generated in the through hole, and the resist material blocking the through hole is removed by the rapid gas flow.

The sudden gas flow may be obtained by gas injection from a nozzle directed to the through hole.

The sudden gas flow may be obtained by gas suction by a nozzle directed to the through hole.

Further, a decompression box may be arranged at a position opposite to the gas injection nozzle with the substrate interposed therebetween.

The nozzle may be a slit nozzle.

The coating of the resist material on the surface of the substrate can be performed by a curtain coater.

[0014]

In the circuit board manufacturing process, the method for removing clogging according to the present invention is performed after the resist material is applied to the surface of the substrate having through holes and before the resist material is completely dried. Various coating conditions such as the composition and viscosity of the resist material that is applied to the substrate surface to form the circuit pattern and solder mask, and the thickness of the coating film are set so that the optimum coating can be performed according to the purpose. Can be set to.

At the time of coating on the substrate, the resist material may cover the ends of the through holes or enter the inside of the through holes to block the through holes. In carrying out the present invention, it is not necessary to intentionally prevent these situations. This is because the present invention is intended to cause a rapid gas flow in the through hole and to remove the resist material blocking the end portion or the inside of the through hole by its force. Therefore, this clogging removal work needs to be performed after the application of the resist material is completed and before the resist material is completely dried. The rapid gas flow generated in the through hole may be provided by the gas injection from the nozzle directed toward the through hole or the gas suction by the nozzle directed toward the through hole. Further, the decompression box may be arranged at a position opposite to the gas injection nozzle with the substrate sandwiched therebetween.

The resist material covering the ends or the inside of the through holes is pushed by a gas jet or drawn by a gas suction, and is removed outward from the ends or the inside of the through holes.

The substrate coated with the resist material before complete drying may be transported by a transport conveyor that supports both edges of the lower surface of the substrate. Then, nozzles may be arranged on the upper side or the lower side of this transport path so that gas injection or gas suction is performed when the substrate passes through these nozzles. The shape of the nozzle may be a slit nozzle having an opening extending in the width direction of the substrate.

The coating of the resist material on the surface of the substrate can be performed by a curtain coater which is optimized.

[0019]

1 and 2, a substrate 2 whose one surface is coated with a resist material 1 by a curtain coater or the like.
Are conveyed in the direction of arrow 3 by a conveyor device (not shown). As shown in FIG. 1, the upper opening end portion of the small diameter through hole 4 formed in the substrate 2 is covered with the resist material 1. A decompression box 5 for sucking gas is arranged above the substrate transfer path, and a nozzle 6 for injecting gas is arranged facing the decompression box 5 below the transfer path. As can be seen from FIG. 2, the nozzle 6 is formed as a slit nozzle having an opening extending in the width direction of the substrate 2. Further, as shown in FIG. 2, the gas injection nozzle 6 may be arranged in the decompression box 5 ′.

When the substrate 2 in which the resist material 1 is not completely dried is conveyed between the depressurizing box 5 and the nozzle 6 in the operating state, the position of the through hole 4 of the substrate 2 is the position of the nozzle 6. When aligned with the opening position (FIG. 1), the resist material 1 covering the upper opening end of the through hole 4 is pushed upward by the rapid gas flow from the nozzle 6 to pass through the through hole 4. During this time, the decompression box 5 performs a gas suction action. Reference numeral 4'denotes a through hole in which the resist material 1 covering the opening end has already been removed. Although the viscosity of the resist material 1 is relatively low, it may flow into the through holes 4 and become clogged during coating, but the method of the present invention is also effective for removing such resist material 1.

FIG. 3 shows another embodiment for carrying out the method of the present invention. (A) is a case of only injecting a gas flow from below, (b) is a case of only sucking a gas from below,
(C) is a case where gas is only sucked from above.

The gas jetted from the nozzle may be air or a gas of other components.

When the resist material 1 is applied to both surfaces of the substrate 2, the resist material is applied to one surface of the substrate 2 and then the clogging of the through holes 4 is removed as described above, and then the remaining surface is applied. The resist material 1 may be applied and the through holes 4 may be similarly clogged. If the resist material 1 can be applied to both surfaces in a short time, the clogging at both ends of the through hole 4 may be simultaneously removed after the application to both surfaces is completed.

The method of the present invention is also effective when a coating method other than the most ideal curtain coater coating method is used.

The method of the present invention is most suitable for removing the clogging of through holes due to the resist material applied to the substrate for forming a circuit pattern or a solder mask, but the resist material is applied for other purposes. It is also effective when

[0026]

According to the method of the present invention, it is possible to surely remove the clogging of the through holes without applying any restriction to the application of the resist material in the optimum state.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view showing an embodiment of removing a resist material covering an end portion of a through hole by a method of the present invention.

2 is a perspective view of the embodiment shown in FIG. 1. FIG.

FIG. 3 is a schematic side sectional view showing another embodiment of the method of the present invention.

[Explanation of symbols]

1 resist material, 2 substrate, 4 through hole, 5 upper nozzle, 6 lower nozzle.

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[Procedure amendment]

[Submission date] February 2, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (6)

[Claims] 1. In a circuit board manufacturing process, after a resist material is applied to the surface of a substrate having through holes, a rapid gas flow is generated in the through holes before the resist material is completely dried. A method for removing clogging of through-holes in a substrate, characterized in that the resist material that blocks the through-holes is removed by a flow. 2. The clogging removal method according to claim 1, wherein the rapid gas flow is obtained by gas injection from a nozzle directed to the through hole. 3. The clogging removal method according to claim 1, wherein the rapid gas flow is obtained by gas suction by a nozzle directed to the through hole. 4. The method for removing clogging according to claim 2, wherein a decompression box is arranged at a position opposite to the nozzle with the substrate interposed therebetween. 5. The method for removing clogging according to claim 1, wherein the nozzle is a slit nozzle. 6. The method of removing clogging according to claim 1, wherein the resist material is applied to the surface of the substrate by a curtain coater.