JPH05273760A - Formation of resist image - Google Patents

Abstract

PURPOSE:To easily obtain a circuit board having a high density and high accuracy at a low cost by forming a resist film which does not contain bubbles in the holes for through-holes. CONSTITUTION:The entire part of a substrate 1 is immersed into a resist liquid 3 which is adjusted in viscosity and thixotropy to adequate values and is housed in a storage tank 4. The resist liquid having a non-Newtonian property at this time is held fluidized by liquid circulation and is liable to defoam as the liquid viscosity is low on the periphery of the substrate. The bubbles meshed in the holes 10 for the through-holes of the substrate 1 are then emerged from the inside by oscillation defoaming and vibration defoaming, ride in the liquid flow, float on the liquid surface and are removed. The substrate 1 held stuck with the resist liquid 3 is then pulled up from the storage tank 4. The photosensitive resist liquid 3 sticks uniformly at a sufficient thickness to the entire part of the surface of a conductor metallic layer 2 including the inner peripheral surface of the holes 10 for the through-holes of the substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resist film in a manufacturing process of a printed wiring board used as an electronic base material.

[0002]

2. Description of the Related Art As a method of forming a resist film in a manufacturing process of a printed wiring board, a screen printing method, a dry film method, a roll coater method, a spin coating method,
The electrodeposition method is known. However, there is a problem in forming a resist film which is a thin film and has a high film thickness accuracy by the above-mentioned conventional method, which is required for manufacturing a fine and highly accurate printed wiring board. That is, in the printing method of, it is difficult to control the resist coating film thickness with accuracy, and in the dry film method, it is difficult to thin the film because the film formed in advance is heated and pressed, and the roll coater method of However, it cannot be applied unless it is a flat plate, and it is difficult to apply it to the inside of the through hole hole. The spin coating method is difficult to apply to a large substrate, and the electrodeposition method is that the resist coating has pinholes. Under the present circumstances, there are problems when they easily occur and it is difficult to control the electrodeposition liquid.

Particularly, in the production of a printed wiring board having holes for through holes, the printing method, the roll coater method, and the spin coating method have poor through-hole reliability and are filled with holes made of an ink for etching resistance. There is a method of forming a circuit in a state where the through hole is filled to protect the wall surface of the hole, and a method of removing the hole clogging of the resist by suction as described in JP-A-63-38289. It is difficult to apply to substrates with a large aspect ratio (plate thickness / hole diameter).

The dry film method is difficult to apply to the production of through-hole wiring boards.

[0005]

As a method for solving these conventional problems, the inventors of the present invention previously prepared a substrate having a conductor metal layer formed on the entire surface of the substrate including through-hole holes. We developed a method to form a resist film by dipping the resist solution in a photosensitive resist solution contained in a liquid storage tank and pulling it up to deposit the resist solution on the entire surface of the conductor metal layer including the holes for through holes, and applied for a patent. (See Japanese Patent Application No. 1-444115). According to this method, the necessary and sufficient resist layer can be surely formed even inside the through hole hole by an extremely simple operation.

However, according to the method of this prior invention, as shown in FIG.
There was a problem that the air bubble B was bitten inside. This bubble B
However, the through-hole edge portion 11 or the through-hole hole 1 is pulled up from the resist solution and heated and dried.
0, the thin portion or the discontinuous portion of the resist layer 30 is locally generated on the inner peripheral surface. Thus, the resist layer 30
In the portion not sufficiently covered with, the conductor metal layer 2 is removed by etching in the etching step, which causes disconnection of the conductor circuit and circuit failure, which causes deterioration of through hole reliability.

Therefore, the problem to be solved by the present invention is to uniformly form a thin resist layer on the entire surface of the substrate, and particularly to form a resist film containing no bubbles inside the through-hole. As a result, a method of forming a resist film that can easily and inexpensively implement a high-density, high-accuracy circuit board including minute diameter through-holes or landless through-holes, and that is capable of manufacturing through-holes with high reliability is provided. Is to provide.

[0008]

A method for forming a resist film according to the present invention, which solves the above-mentioned problems, is to immerse a substrate in a resist liquid fluid having non-Newtonian property and defoam it.
It is characterized in that the resist solution is applied to the substrate by pulling it up. The defoaming method applied to the present invention includes vibration defoaming, swing defoaming and the like. In these defoaming methods, the substrate immersed in the resist solution is vibrated or shaken to expel air bubbles inside the through-hole.

The method of vibrating the substrate is not particularly limited, but it is preferable to apply vibration in the plate surface direction or the thickness direction of the substrate. As the mechanism for vibrating the substrate, for example, as shown in FIG. 4, in addition to the vibrating mechanism 6 using the vibrating motor 60, various vibrating mechanisms in ordinary mechanical devices can be adopted. It is also possible to incorporate an ultrasonic vibration generator into the tank and vibrate both the liquid and the substrate. In the figure, 2 is a substrate, 3 is a liquid, and 4 is a tank. As a mechanism for vibrating the substrate, the support portion 65 of the substrate may be mechanically operated as shown in FIG. Specifically, a mechanism that converts the rotation of the drive motor 63 into a linear reciprocating motion via a crank mechanism 64, a cam mechanism, a gear mechanism, or the like can be adopted. In the figure, 2 is a substrate, 3 is a liquid, and 4 is a tank. Moreover, you may use an electromagnetic cylinder, an air cylinder, etc. By adjusting the amplitude, speed, number of times, etc. of the vibration, it is possible to set it so that the bubbles inside the through-hole hole are satisfactorily expelled.

The vibration direction of the substrate is not particularly limited, but it is relatively preferable to apply vibration in the thickness direction of the substrate. When performing the defoaming treatment as described above, by making the resist liquid having non-Newtonian property into a fluid state,
The viscosity of the liquid can be reduced, and the defoaming effect of each defoaming treatment can be further enhanced. The flow rate of the resist solution is not particularly limited, but is preferably 5 to 1000 mm / min, more preferably 10 to 500 mm / min.

As a mechanism for bringing the resist solution into a fluid state, a circulation device as shown in FIG. 1 is exemplified. Storage tank 4
An overflow tank 46 and a circulation pipe 49 are provided next to each other with a partition plate sandwiched therebetween. A pump 43 for forcibly circulating the photosensitive resist solution 3 and an appropriate valve 45 as needed are attached in the middle of the circulation pipe 49. The circulation pipe 49 introduced into the liquid storage tank 4 discharges the photosensitive resist liquid 3 from the discharge port 48. Further, when the resist liquid is brought into a fluid state, the bubbles ride on the liquid flow and the through-hole holes 10 are formed.
Since it does not stay around (see FIGS. 4 and 5), the defoaming process is effectively performed.

FIG. 2 shows a cross section of the through-hole hole in which the resist liquid layer is formed by the above method. If the defoaming effect is sufficient, a resist partition wall 31 that blocks the through hole is formed in the through hole hole 10. This is hole 1 for through hole
The resist liquid 3 that has entered 0 remains as it is and can be used as an etching resist layer of a printed wiring board.

Here, the coating thickness of the resist solution on the substrate can be adjusted by adjusting the viscosity and thixotropy of the resist solution 3 or the pulling rate of the substrate. When the resist layer 30 is used as an etching resist layer, on the inner surface of the through hole hole 10 and the substrate 1
A resist film 30 having a thickness of at least 0.5 μm or more on the surface
Must be formed.

The tank used in the present invention may be any tank made of a material having solvent resistance enough to withstand the resist solution, and the shape is not particularly limited. The material to be coated to form the resist film in the present invention is mainly a substrate material used in a usual printed wiring board, such as a glass epoxy copper-clad laminate or a paper phenol copper-clad laminate. It is not limited to. When the object to be coated is a substrate having holes for through holes, etc., it is general that the surface of the substrate is entirely covered with a metal layer by a method such as plating. In the present invention, on this metal layer, A resist film is formed so as to cover all of the through hole and the resist layer.

As the resist solution used in the present invention, a general photosensitive resist can be applied, and the photosensitive resist solution is classified into a positive type and a negative type. Either type can be used in the present invention, but the aspect ratio is large. For through holes, the positive type is preferable. The resist liquid is not particularly limited as long as it has a non-Newtonian property. As an example, a photosensitive resist solution containing a thixotropic agent and the like is illustrated. As components of the photosensitive resist solution, thermosetting resin components or alkali-soluble resin components such as acrylic polymers, epoxy resins, or novolac resins are used as a base, and various ordinary photopolymerization initiators and photopolymerization initiators are used. Accelerator, photopolymerizable monomer,
Oligomers, photodegradable compounds, and diluents such as organic solvents, thermosetting agents, and thixotropic agents,
It is a mixture of some viscosity modifiers, colorants, defoamers, stabilizers and the like. Specific compounds and the like of each compounding component other than the regulator are the same as those used in ordinary wiring board production.

The viscosity of the resist liquid having non-Newtonian property is not particularly limited, but it can be determined by using a B type viscometer (manufactured by Tokyo Keiki Co., Ltd.). 1-No. When using 3 rotors and showing the value measured at a rotation speed of 60 rpm, 10 to 1500 c
ps is preferable, and more preferably in the range of 50 to 500 cps. The thixotropic value of this resist solution is preferably in the range of 1.2 to 9.0, and the thixotropic value in the present invention is a value represented by the following formula.

Thixotropic value = viscosity at 6 rpm /
Viscosity at 60 rpm If the thixotropy value is less than 1.2, the resist layer thickness at the through hole edge portion cannot be sufficiently secured, and if the thixotropy value exceeds 9.0, the thixotropy value in the circuit pattern forming part is not sufficient. The variation of the etching resist layer becomes too large.

[0018]

In the resist film forming process, the substrate is immersed in a non-Newtonian resist fluid and defoamed, and then the substrate is pulled up, so that the entire substrate including the through-hole holes is necessary and sufficient. A resist solution with a limited thickness adheres. The resist layer thus formed has no local thin layer portion or intermittent portion due to bubbles, and the entire substrate surface is reliably covered with the resist film. It is inferred that when the resist solution having non-Newtonian property is in a flowing state, the viscosity of the resist solution is lower than that in a stationary state and the defoaming effect in the defoaming process is enhanced. At this time, the bubbles trapped inside the through-hole of the substrate come out from the inside of the through-hole and ride on the liquid flow,
Eventually, it floats to the liquid surface and is removed.

When immersed in a Newtonian resist fluid liquid, or immersed in a stationary state, for example, a small diameter through hole of 0.4 mmφ or less or an elongated through hole with an aspect ratio of 4 or more causes bubbles. Although the biting was unavoidable, the generated bubbles can be completely removed by immersing in the non-Newtonian resist fluid liquid as in the present invention.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 2 and 3 show an embodiment of the resist film forming method of the present invention. First, the resist layer 3 is formed on the substrate 1. At this time, the substrate is pretreated if necessary. The pretreatment is to physically or chemically polish the surface of the substrate 1, that is, the conductor metal layer 2. The specific polishing means is the same as the method for a normal wiring board. The polishing amount is preferably about 0.1 to 10 μm, more preferably about 0.2 to 2 μm. The above-described pretreatments are performed as needed, and need not be performed if not necessary.

Next, the entire substrate 1 is immersed in the resist solution 3 stored in the liquid storage tank 4 with the viscosity and thixotropy value being appropriately adjusted. At this time, the resist liquid having a non-Newtonian property is in a fluidized state due to the liquid circulation, and the liquid viscosity is reduced around the substrate to facilitate defoaming. The bubble B (see FIG. 6) that has been bitten into the through hole hole 10 of the substrate 1 comes out of the through hole hole 10 due to the swing defoaming or the vibration defoaming, and becomes a liquid flow. It floats up to the liquid surface and is removed. At this time, since it does not remain in the through hole hole 10, the defoaming process is efficiently performed.

Next, the substrate 1 with the resist solution 3 attached thereto is pulled up from the liquid storage tank 4. At this time, the photosensitive resist liquid 3 adheres to the entire surface of the conductor metal layer 2 including the inner peripheral surface of the through hole hole 10 of the substrate 1 with a sufficient thickness and uniformly. After that, the resist solution 3 is dried to obtain the substrate 1 in which the entire surface of the conductor metal layer 2 is covered with the resist film 30. The resist solution 3 is formed into a film by the heat treatment in this drying step. Resist liquid 3
Are sufficiently and uniformly adhered to the inside of the through-hole 10 of the substrate 1 and the entire other surface.

According to the method of the above invention, the resist liquid 3
The thickness of the resist liquid 3 applied to the substrate 1 can be adjusted by adjusting the viscosity, the thixotropic value, or the pulling rate from the resist liquid 3. For example, it is possible to form a thin film of several μm level by adjusting the viscosity of the resist solution 3, the thixotropy value and the pulling rate from the resist solution within the above range.

The substrate 1 on which the resist film is formed as described above is exposed to ultraviolet rays using an appropriate mask pattern when the resist film is an etching resist, for example, and then the unnecessary portion of the resist film is removed by development. Then, etching can be performed to form a desired pattern. According to the present invention, it is possible to form a resist film which is a thin film having a level of several μm, and therefore a very fine pattern can be accurately formed.

Next, a specific example in which the method for forming a resist film according to the present invention is actually applied to manufacture a printed wiring board will be described with reference to Table 1. -Example 1-As a substrate 1, a 300 mm x 300 mm x 1.6 mm glass epoxy copper-clad laminate was used. This substrate has a hole diameter of 0.4 mm (aspect ratio of 4) and a number of holes of 5 by drilling.
00 through-holes 10 are formed.

Next, as a pretreatment for forming the etching resist layer, the oscillator metal polishing is used to form the conductor metal layer 2.
The surface was polished to about 0.8 μm. After that, this copper-clad laminate is immersed in a non-Newtonian photosensitive resist liquid fluid having a flow rate of 100 mm / min to oscillate and defoam the air bubbles B inside the through-hole holes 10, and then into the through-hole holes 10. On the other hand, the conductor metal layer including the through-holes 10 was formed by pulling it up in a direction perpendicular to it.

At this time, the viscosity of the photosensitive resist solution used was non-Newtonian, the viscosity was 200 cps, and the thixotropy value was 4.4. The swing defoaming was performed with a swing width of 20 mm, a swing speed of 30 times / minute, and a swing frequency of 30 times. After the etching resist liquid layer made of a photosensitive resist was dried at 90 ° C., it was exposed to ultraviolet rays using a positive mask pattern and developed to form an etching resist layer 30 having a predetermined pattern.
The thickness of the etching resist layer 30 is 13 in the plane part of the substrate.
μm, and 5 μm at the through hole edge portion.

At this time, by observation with a scanning electron microscope or a metallographic microscope, no bubbles B remain inside all the through-hole holes 10, and the through-hole holes 1
It was also confirmed that the inner wall surface and the peripheral portion of No. 0 were not covered with the etching resist layer 30 at all. Next, the conductor metal layer 2 was etched by a usual etching method to form a wiring circuit. After the etching process was completed, the etching resist layer 30 was entirely peeled off with a 3% NaOH solution to obtain a wiring board with through holes.

When a through-hole conductivity test was conducted on this wiring board with through-holes, the occurrence rate of defects such as disconnection was 10 ppm or less (the number of through-holes was 10000 (20 boards) and no disconnection was found in the through-holes). It is demonstrated that the through hole reliability is extremely higher than that of the wiring board with through hole manufactured by the conventional "dip method" in which the photosensitive resist liquid having Newtonian property is used (Comparative Example 2).
reference).

Example 2 As a substrate 1, a 96% alumina substrate (4 ″ × 4 ″ × 0.
8 mm), laser processing was used to form through-holes 10 having a hole diameter of 0.3 mm (aspect ratio 2.67) and a number of holes of 280. The surface of the alumina sintered substrate 1 and the inner wall surface of the through hole hole 10 are immersed in hot phosphoric acid to be uniformly roughened, and then the surface of the substrate 1 and the inner wall surface of the through hole hole 10 are chemically plated. A copper layer having a thickness of 10 μm was formed as a conductor metal layer 2.

Next, as a pretreatment for forming the etching resist layer, the surface of the conductor metal layer 2 of the substrate 1 was polished by about 0.5 μm by using oscillation polishing. afterwards,
The substrate 1 is dipped in a non-Newtonian photosensitive resist liquid fluid having a flow rate of 50 mm / min to form a through hole hole 10
After the internal bubbles B are degassed by vibration (vibration time of 2 minutes), the air bubbles B are pulled up in a direction perpendicular to the through hole holes 10 to form an etching resist liquid layer on the entire surface of the conductor metal layer 2 including the through hole holes 10. Formed. The viscosity of the photosensitive resist solution used at this time is non-Newtonian and the viscosity is 150
cps and thixotropic value was 4.2.

After the etching resist liquid layer composed of the photosensitive resist liquid layer is dried at 90 ° C., it is exposed to ultraviolet rays using a positive type mask pattern and developed,
An etching resist layer 30 having a predetermined pattern was formed. The thickness of the etching resist layer 30 was 8 μm in the plane of the substrate and 6 μm in the through hole edge portion. At this time, as a result of observation with a scanning electron microscope or a metallographic microscope, no bubbles B remain inside all the through-hole holes 10, and etching resist is applied to the inner wall surface and the peripheral portion of the through-hole holes 10. It was also confirmed that the layer 30 was not covered at all.

Next, the conductor metal layer 2 was etched by a usual etching method to form a wiring circuit. After the etching process is completed, the etching resist layer 30 is all 3
Peeling and removal was performed with a% NaOH solution to obtain a wiring board with through holes. When a through-hole continuity test was conducted on this wiring board with through-holes, the failure occurrence rate was 20 ppm or less (the number of through-holes was 5,600 (20 boards), and there was no disconnection in the through-holes). , It was proved that the through hole reliability is extremely higher than that of the conventional wiring board with through holes, which is manufactured by the "dip method" of immersing in the direction perpendicular to the through hole holes and pulling it up as it is.

Example 3 A ceramic substrate was used as the substrate 1. First, Al ₂
96 parts by weight of O ₃ powder and 4 parts by weight of a sintering aid such as SiO ₂ , CaO, MgO are mixed, and 12 parts by weight of an organic substance (binder, plasticizer) is added to this mixture, A ceramic green sheet was obtained by forming into a sheet by the doctor blade method. After heating this green sheet to a semi-cured state, it is pressed with a mold to have a hole diameter of 0.
A through-hole hole 10 of 4 mm (aspect ratio 2) was formed. The green sheet was dried at 150 ° C and then fired at 1600 ° C to obtain a substrate 1 made of a ceramic substrate having through-holes 10.

After roughening the surface of the substrate 1, a chemical plating method was performed, and then a copper layer having a thickness of 35 μm was formed by an electrolytic plating method to form a conductor metal layer 2. Flow rate of this substrate is 1
The substrate B is immersed in a non-Newtonian photosensitive resist liquid fluid of 50 mm / min to oscillate and defoam the bubbles B in the through-hole holes 10 and then pulled up in a direction perpendicular to the through-hole holes 10 to obtain a substrate. An etching resist liquid layer was formed on the entire surface. At this time, the viscosity of the photosensitive resist solution used was 170 cps, and the thixotropy value was 4.3. The swing defoaming is performed with a swing width of 10 mm and a swing speed of 20.
The number of rotations / minute was 40 and the number of times of rocking was 40.

After the etching resist liquid layer made of a photosensitive resist was dried at 90 ° C., it was exposed to ultraviolet rays using a positive mask pattern and developed to form an etching resist layer 30 having a predetermined pattern. .. The thickness of the etching resist layer 30 was 12 μm in the plane portion of the substrate and 5 μm in the through hole edge portion. As for the other execution conditions, when a wiring board with through holes was manufactured in the same steps as in Example 1, no defects such as disconnection were observed as in the above Examples, and excellent through hole reliability was obtained. It was a thing.

-Example 4-Pore diameter 0.3 mm (aspect ratio 5.33), number of pores 500
Using a substrate on which the through-hole holes 10 are formed,
Except that the swing defoaming was performed with a swing width of 20 mm, a swing speed of 60 times / minute, and a swing number of 60 times, the etching resist having a predetermined pattern was formed in the same process as in Example 2. Layer 30 was formed. The thickness of the etching resist layer 30 was 15 μm in the plane portion of the substrate and 4 μm in the through hole edge portion.

At this time, as a result of observation with a scanning electron microscope or a metallographic microscope, no air bubbles B remain inside all the through-hole holes 10, and the inner wall surface and the peripheral portion of the through-hole holes 10 are completely removed. Etching resist layer 30
It was also confirmed that there were no uncoated areas.
As for the other execution conditions, when a wiring board with through holes was manufactured in the same steps as in Example 1, no defects such as disconnection were observed as in the above Examples, and excellent through hole reliability was obtained. It was a thing.

Example 5 As the substrate 1, a 96% alumina substrate (4 ″ × 4 ″ × 2.
4 mm) and the through hole 10 having a hole diameter of 0.3 mm (aspect ratio of 8) and the number of holes of 280 was formed by laser processing. Etching resist layer 30 having a pattern
Formed. The thickness of the etching resist layer 30 was 16 μm in the plane portion of the substrate and 3 μm in the through hole edge portion.

At this time, it was found by observation with a scanning electron microscope or a metallurgical microscope that the air bubbles B remained inside some of the through-hole holes 10. However, when the conductor metal layer 2 was etched by the same etching treatment method as in the above-mentioned examples to manufacture a wiring board with through holes, no defects such as disconnection were observed as in the above-mentioned examples, and excellent through It was the hall's reliability.

-Comparative Example 1-In Example 1, without circulating the photosensitive resist solution,
An etching resist layer 30 having a predetermined pattern was formed in the same process as in Example 1 except that the insulating substrate 1 was pulled up in a direction perpendicular to the through hole hole 10. At this time, it was found by observation with a scanning electron microscope or a metallurgical microscope that some of the bubbles B remained inside the through-holes 10.

The conductor metal layer 2 was etched by the same etching treatment method as in the above-mentioned embodiment to produce a wiring board with through holes, and a through hole conductivity test was conducted.
The rate of defects such as disconnection is about 2000ppm (10000 through holes (20 substrates)
It was found that the defect occurrence rate was higher than that in Example 1. As a result, the wiring board with through-holes manufactured by immersing the photosensitive resist solution in the photosensitive resist solution while circulating the photosensitive resist solution does not circulate the photosensitive resist, but does not circulate the photosensitive resist. It was proved that the through hole reliability was much higher than that in the case of immersing in the substrate and pulling up the substrate as it was.

Comparative Example 2 In Example 1, the photosensitive resist solution has a Newtonian viscosity of 100 cps and a thixotropic value of 1.
An etching resist layer 30 having a predetermined pattern was formed by the same steps as in Example 1 except that the etching resist layer 30 was 1. The thickness of the etching resist layer 30 is 8 μm in the plane portion of the substrate.
However, it was very thin at 1 μm or less at the through hole edge portion. At this time, the air bubbles B did not remain inside the through hole hole 10 by observation with a scanning electron microscope or a metallographic microscope.

The conductor metal layer 2 was etched by the usual etching method as in each of the above-mentioned examples to manufacture a wiring board with through holes, and a through hole conductivity test was conducted. Was seen in large numbers.
The defect occurrence rate such as disconnection was 60, and it was found that the defect occurrence rate was extremely high as compared with the examples. With this result,
It has been proved that the resist solution having non-Newtonian property has extremely high through-hole reliability as compared with the resist solution having Newtonian property.

The above results are summarized in the table below.

[0046]

[Table 1]

[0047]

According to the method of forming a resist film of the present invention, a thin film resist can be uniformly formed on the entire surface of a substrate, and a resist film containing no bubbles can be formed inside the through-hole. As a result, it is useful as a method for forming a resist film for producing a high-density, high-precision circuit board including minute diameter through holes or landless through holes simply, at low cost, and with reliable through holes.

[Brief description of drawings]

FIG. 1 is a schematic high-pitched view showing a resist solution circulating device.

FIG. 2 is an enlarged cross-sectional view of a main part of a substrate on which a resist solution is attached.

FIG. 3 is a cross-sectional view showing a resist liquid attaching step.

FIG. 4 is a perspective view showing an example of vibration defoaming.

FIG. 5 is a perspective view showing an example of rocking defoaming.

FIG. 6 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Conductor metal layer 3 Resist liquid 4 Storage layer 6 Vibration mechanism 10 Through hole hole 11 Through hole edge part 30 Etching resist layer 31 Resist partition wall 43 Circulation pump 45 Valve 46 Overflow tank 48 Discharge port 49 Circulation pipe 63 Vibration motor 64 Crank mechanism 65 Insulating substrate support B Bubbles

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[Procedure amendment]

[Submission date] September 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art As a method of forming a resist film in a manufacturing process of a printed wiring board, a screen printing method, a dry film method, a roll coater method, a spin coating method,
The electrodeposition method is known. However, there is a problem in forming a resist film which is a thin film and has a high film thickness accuracy by the above-mentioned conventional method, which is required for manufacturing a fine and highly accurate printed wiring board. That is, in the printing method, it is difficult to control the thickness of the resist coating film with high accuracy, and in the dry film method, it is difficult to thin the film because the film formed in advance is heat-pressed. The roll coater method cannot be applied unless it is a flat plate, and it is difficult to apply it inside the holes for through holes. The spin coat method is difficult to apply to a large substrate, and the electrodeposition method is a resist coating. Currently, there are problems in that pinholes are likely to occur and it is difficult to control the electrodeposition liquid.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

In the dry film method, a small diameter film is used .
It is difficult to apply to the land-less through-hole wiring board called.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Next, the entire substrate 1 is immersed in the resist solution 3 stored in the liquid storage tank 4 with the viscosity and thixotropy value being appropriately adjusted. At this time, the resist liquid having a non-Newtonian property is in a fluidized state due to the liquid circulation, and the liquid viscosity is reduced around the substrate to facilitate defoaming. The bubble B (see FIG. 6) that has been bitten into the through hole hole 10 of the substrate 1 comes out of the through hole hole 10 due to the swing defoaming or the vibration defoaming, and becomes a liquid flow. It is divided lifted to ride liquid surface. At this time, since it does not remain in the through hole hole 10, the defoaming process is efficiently performed.

Claims (3)

[Claims] 1. A resist liquid is applied to a substrate by immersing a substrate having a conductor metal layer formed on the surface in a non-Newtonian resist liquid fluid, defoaming the substrate, and then pulling it up. Method for forming resist film. 2. The substrate includes a through hole hole, and a resist coating having a thickness of at least 0.5 μm is formed on the conductor metal layer surface of the through hole edge portion and the inner peripheral surface of the through hole hole, and the through hole is used. 2. The method of forming a resist film according to claim 1, wherein a resist partition wall that blocks the penetration is formed in the hole. 3. The method for forming a resist film according to claim 1, wherein the defoaming treatment is shaking or vibration of the substrate.