JPH02144988A - Manufacture of wiring board with through hole - Google Patents

Abstract

PURPOSE:To prevent disconnection of a conductor circuit and circuit failure in the peripheral part of a through hole and improve reliability by covering the peripheral part of an opening for the through hole with a photoresist for printing in which a filler is contained and forming an etching resist layer thereon. CONSTITUTION:An opening for a through hole 10 is provided in an insulating base board 1, and a conductive metal layer 2 is formed on both top and bottom surfaces and on the inner wall surface of the opening 10. Then, a photoresist for printing in which a filler is contained is filled within the opening 10, and after drying thereof, it is irradiated by ultraviolet rays to photoset and form a filled part 4. Further, the same photoresist for printing in which the filler is contained is applied on both whole surfaces and dried. Then, both surfaces are irradiated by ultraviolet rays to expose this photoresist. At that time, a suitable mask is used to cause only the inner side and peripheral part 11 of the opening 10 to set to form a protective part 5, and other surface part of the insulating base board 1 is removed after development. Next, after an etching resist layer 3 is formed on the conductor metal layer 2, etching treatment is carried out to form a circuit pattern. Then, the filled part 4 and the protective part 5 are peeled and removed to form a wiring board with the through hole.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a wiring board with through holes,
Specifically, the present invention relates to a method of manufacturing a wiring board having a so-called through hole, which is formed through the wiring board and used as a component lead wire insertion hole for mounting an electronic component.

[Conventional technology]

The method for producing a wiring board with through holes is as follows: First, a through hole is made in a commercially available insulating substrate or copper clad laminate, etc., and then electroless plating or a combination of this and electrolytic plating is performed. A conductive metal layer that will become a wiring circuit is formed on the inner wall of the through-hole hole and the surface of the substrate.

As a method of forming a circuit pattern on this conductive metal layer,
There are several ways.

(1) Pattern the etching resist on the surface of the conductive metal layer by printing or photographing, while protecting the hole walls by filling the through-hole holes with hole-filling ink made of etching-resistant ink by printing or other means. The so-called ``hole-filling method'' then forms a circuit by etching the conductive metal layer.

(2) Laminate a film resist such as dry film on the through-hole hole and the surface of the conductor gold layer,
After forming an etching pattern by the so-called "tenting method," unnecessary conductive metal layers other than the circuit pattern are dissolved and removed using an etching solution such as cupric chloride, ferric chloride, or alkaline etchant. Next, the etching resist is removed using a resist stripping solution such as an organic solvent or an inorganic alkaline solution to form a circuit.

The above two methods are common, but the other method is (3) To obtain a circuit made of conductive metal, only the circuit pattern part is plated with a different metal and the circuit is formed by selective etching. (4) "pattern plating method" or (4) so-called "additive method" in which electroless plating is applied only to the parts necessary for the circuit. These methods are described, for example, in Japanese Patent Application Laid-Open No. 54-50872,
It is disclosed in Japanese Patent Application Laid-Open No. 187095/1984.

[Problem to be solved by the invention]

Among the above methods, (2) "tenting method"
If there is a through hole, it is impossible to use liquid resist as it is, so a film resist is used, but due to the thickness of the resist, 1
It is difficult to form fine circuit patterns of 00μ or less. The "pattern plating method" (3) allows high-density patterns to be finished with good precision, but requires overlay plating, which has the disadvantage of being expensive in terms of equipment.

The "additive method" (4) has recently been attracting attention in the field of industrial applications, but it has problems such as the need to use a special adhesive-attached laminate containing a catalyst.

Therefore, the "hole-filling method" is considered to be a promising method because it can be produced at a relatively low cost and is advantageous in terms of circuit accuracy compared to other manufacturing methods. There is a problem of poor reliability.

Figure 3 shows the problems with the "hole-filling method." The diagram is
This figure shows the state of the vicinity of the through-hole before etching when a heat-curable hole-filling ink conventionally used for boat fishing is used as the hole-filling ink. A conductive metal layer 2 formed by plating is provided on both the front and back surfaces of the insulating substrate 1 and the inner wall surface of the through-hole hole 10, and a heat-curable hole filling layer is provided inside the through-hole hole 10. The ink 4' is filled. On this conductor metal Fi2, an etching pattern is formed by an etching resist layer 3 corresponding to a desired circuit pattern.

However, when the heat-curable hole-filling ink 4' is heat-cured, the solvent contained in the ink evaporates and evaporates, resulting in a large volumetric contraction. A depression or a step is formed between the surface of the substrate 1 and the surface of the substrate 1.

When the etching resist liquid is applied to the peripheral edge part 11 having a recess or step as described above, the resist liquid does not adhere to the peripheral edge part 11 sufficiently, and the thickness of the finished resist layer 3 is smaller than that of the peripheral edge part of the through-hole hole 10. Part 30 covering 11
It becomes thinner.

If the etching process is performed in this state, in the thin peripheral portion 30 of the resist layer 3, even the internal conductive metal layer 2 will be etched through the thin resist layer 3.
This caused problems such as disconnections and circuit defects in the conductor circuits of manufactured wiring boards. That is,
This means that the reliability of the conductor circuit in the through-hole area is poor. Therefore, the object of this invention is to prevent disconnection of the conductor circuit and circuit defects at the periphery of the through-hole in the above-mentioned "hole filling method", and to An object of the present invention is to provide a method for manufacturing a through-hole wiring board that can improve the reliability of holes.

[Means to solve the problem]

To solve the above problems, the present invention uses a filler-containing printing photoresist as a filling agent to protect through-hole holes, and also uses a filler-containing printing photoresist that also protects the periphery of the through-hole holes. Then, a notching resist layer is formed on top of that.

[For production]

Filler-containing photoresists for printing are cured by photocuring, but the volumetric shrinkage at this time is less than that of conventional heat-curable hole-filling inks, so when filled into through-holes and cured, , dents and steps are less likely to occur at edges, that is, peripheral portions, and the peripheral portions of through-hole holes are less likely to become thin when an etching resist solution is applied. If the periphery of the through-hole is covered with a filler-containing printing photoresist, no dents or steps will be formed on the periphery of the through-hole, and the periphery can be well protected. If the etching resist solution is applied after covering the inside and peripheral part of the through-hole hole with filler-containing printing photoresist, the thickness will be sufficient for the peripheral part of the through-hole hole without any dents or steps. An etching resist layer is formed, and even if the etching resist layer is thin, if it is combined with a filler-containing printing photoresist that covers the underlying conductive metal layer, a sufficient thickness can be secured, and the periphery of the through-hole hole can be thickened. The conductive metal layer can be reliably protected from etching. The material that fills the through-hole and the material that protects the periphery are
If both are photoresists, there is no fear that the solvent component in the resist will react with the etching resist and cause it to melt or peel off.

〔Example〕

FIG. 1 is a process flowchart showing an embodiment of the method for manufacturing a wiring board with through holes according to the present invention, and the process will be sequentially explained according to this process flowchart.

Further, FIG. 2 shows the cross-sectional structure of the wiring board in the middle of the process, and in the drawing, the same reference numerals are given to the same structural parts as in the above-described conventional example.

The insulating substrate 1 that is the material of the wiring board includes paper-based phenol resin, paper-based epoxy resin, paper-based polyester resin, glass-based epoxy resin, glass-based Teflon resin, glass-based polyimide resin, and composite resin. Materials used for ordinary wiring boards are used, such as synthetic resin substrates, such as synthetic resin substrates, full-flexure insulating substrates made of metals such as aluminum and iron covered with epoxy resin, and ceramic substrates. It is also possible to use a copper-clad laminate in which a conductive gold layer 2 made of copper is previously formed on the surface of the insulating substrate 1 as described above.

A hole 10 for a through hole is made in an insulating substrate 1.

As a method for forming the through-hole holes 10, methods similar to those for ordinary wiring boards, such as drilling and laser processing, are used. When a ceramic substrate is used as the insulating substrate 1, a method may also be adopted in which a ceramic green sheet before firing is subjected to a hole punching process or the like and then fired. The diameter of the through-hole hole 10 is usually 1.
The pore size is 0 mm or less, but depending on the application, the pore size may be larger. Cutting debris and smear may be generated during this drilling process, and when it is necessary to remove these cutting debris, physical treatment methods such as high-pressure water washing, sandblasting, sulfuric acid method, chromic acid method, etc. Hole 1 for through hole using the chemical treatment method of
Wash 0.

A conductive metal layer 2 is formed by plating on both the front and back surfaces of the insulating substrate (or copper-clad laminate) 1 in which the through-hole hole 10 is formed, and on the inner wall surface of the through-hole hole 10. Before plating the insulating substrate 1, if necessary, the surface of the insulating substrate 1 and the inner wall surface of the through-hole hole 10 are degreased and soft etched, and then metallic palladium is deposited. Keep the surface active. The insulating substrate 1 that has been pretreated as described above is immersed in a chemical plating bath or the like to form a conductive metal layer 2 of copper, nickel, gold, or the like.

The conductive metal layer 2 obtained by the chemical plating method as described above is
Since it is a thin layer of about 0.1 to several microns, if a thicker conductor metal M2 is required, after forming the conductor metal F712 by the chemical plating method, a thicker conductor metal j5t2 is formed by electrolytic plating. form. When a copper-clad laminate is used instead of the insulating substrate 1, part of the process of forming the conductive metal N2 can be omitted.

Next, the inside of the through-hole hole 10 is filled with a filler-containing printing photoresist, dried at 60 to 120°C, and then irradiated with ultraviolet rays to be photocured to form the filling part 4. The higher the filler content of the filler-containing printing photoresist that forms the filling part 4, which protects the inner wall surface of the hole 10 from processing in subsequent steps, the smaller the volumetric shrinkage during curing will be. If the content is too large, it will be difficult to peel and remove the resist in a subsequent process. Therefore,
The filler content used is preferably 0.1 to 10%, more preferably 0.5 to 3%.

As the material to be filled in the filling part 4, solvent-based fillers such as conventional heat-dried hole-filling inks are not preferred. In other words, heat-dried hole-filling inks remove the ta-containing solvent contained in the ink by heating. Since a dry film is obtained by evaporation and evaporation, as described above, the hole-filling ink filled inside the through-hole hole 10 and the photosensitive etching resist applied to the surface of the insulating substrate 1 in a subsequent process are mixed. The hole-filling ink reacts with the solvent component, causing the hole-filling ink to dissolve or peel off, and the thickness of the resist layer becomes thinner at the periphery of the through-hole, that is, at the inner periphery of the through-hole land. This is because it will be etched.

As a specific filling material, it is preferable to use a material that is hard to be attacked by etching resist etc. in the subsequent process and has as little volume shrinkage as possible during curing. A variety of filled printing photoresists can be used.

For example, the components of the UV-curable photoresist mentioned above include various acrylic oligomers, reactive diluent monomers such as acrylic esters, and photopolymerization initiators.
Contains silica, talc and other fillers.

After forming the filling portion 4 as described above in the through-hole hole 10, a printing photoresist containing a filler similar to the filling portion 4 is further applied to the insulating substrate l by screen printing.
Apply to both sides and let dry. When applying the filler-containing printing photoresist, the through-hole hole 10
As for the peripheral edge part, even if it becomes a little thinner than other parts due to the dents and steps of the filling part 4, it is sufficient to cover the filler-containing printing photoresist with a certain thickness. Thereafter, both sides of the insulating substrate 1 are irradiated with ultraviolet rays to expose the filler-containing printing photoresist. At this time, using a suitable mask, only the area from the inside of the through-hole hole 10 to slightly outside of the peripheral edge portion 11 is cured, and the other surface portion of the insulating substrate 1 is removed after development. thus,
A protective portion 5 is formed to cover the peripheral portion 11 from the surface of the through-hole hole 10.

The material of the photoresist forming the protective part 5 may be exactly the same as that of the filling part 4, or the same developing solution may be used so that the forming process of the protective part 5 does not adversely affect the filling part 4 inside. A printing photoresist material containing a filler different from that of the filling portion 4 can also be used as long as there is no fear of dissolution and peeling in the subsequent etching process. Although the thickness of the protective portion 5 is not particularly limited, the thickness of the through-hole hole 10
It is preferable that the circumferential edge portion 11 has a thickness of at least 1μ or more.

Next, an etching resist layer 3 is formed on the conductive metal layer 2 of the insulating substrate 1. Specifically, a commonly used photosensitive liquid etching resist is applied to the entire surface of the insulating substrate 1 and dried, then exposed to ultraviolet light using an appropriate mask pattern, and developed. An etching resist r43 is formed by a so-called photoresist method or the like to form an etching pattern. As the etching resist material used in such a photoresist method, either a positive type or a negative type may be used, but it is necessary to use the same developer as the filler-containing printing resist used for the filling portions 4, etc., or, It is preferable to use a material that does not melt or peel off even when used in combination with the material of the filling part 4 and the protection part 5. As a method for applying the etching resist material, conventional application means such as a spinner, a roll coater, and printing are employed. If the etching resist layer 3 is formed using such a photoresist method, it becomes possible to form a fine pattern with a line width and a line spacing of 30 mm, which is impossible with other methods.

FIG. 2 shows the insulating substrate 1 after the process of forming the etching resist layer 3 as described above has been completed. Both the filling part 4 and the protection part 5, which filled the through-hole hole 10,
Even if the etching resist layer 3 is formed on the etching resist layer 3, a material that does not easily melt, peel off, or repel is used, so the through-hole hole 10 and its peripheral portion 11 can be well protected by the filling part 4 and the protection part 5. has been done. The etching resist layer 3 covering the protective part 5 is thinner at the corners of the stepped portions that occur at the outer peripheral edge of the protective part 5, but there is a sufficient thickness of the protective part 5 between the protective part 5 and the conductive metal layer 2. Since it is interposed, it is reliably protected against etching. Further, the peripheral edge portion 11 of the through-hole hole 10 where the thickness of the protective portion 5 becomes thinner is covered with the etching resist layer 3 with a sufficient thickness. The surfaces of the filling part 4 and the protection part 5 are covered with the etching resist layer 3 and are not exposed to the outside.
The protective part 5 and the filling part 4 are not attacked by the etching process in the post-process.

An etching process is performed on the insulating substrate 1 on which the etching resist layer 3 is formed to form a circuit pattern of the conductive metal layer 2. The etching process is carried out in the same manner as the circuit forming method for ordinary wiring boards.

Next, the etching resist layer 3 and the filling part 4 and protection part 5 made of a filled printing photoresist are peeled off and removed. As the stripping solution, alkaline solutions such as NaOH, Na, Cot, etc., and other ordinary stripping solutions are used, and the insulating substrate 1 can be immersed in these stripping solutions, or the stripping solution can be sprayed onto the surface of the insulating substrate 1. It is carried out by methods etc.

Once the etch resist layer 3, filling portion 4, and protection portion 5 are removed, the wiring board with through holes is completed. If necessary, the surface is polished, degreased, and cleaned as finishing operations. The amount of polishing is preferably about 0.1 to 10μ, preferably 0.2 to 2n. The polishing method is generally the physical treatment method described in the process of treating cutting waste after drilling, but other conventional polishing methods may be employed. As for the degreasing and cleaning methods, the usual wiring board processing methods are used.

In the process described above, the filling part 4 and the protection part 5 are formed in two separate steps, but the filling part 4
When using the same material for the filler-containing printing photoresist that forms the protection part 5, the inside of the through-hole hole 10 and the peripheral portion 11 are covered with the photoresist material at once by one step of screen printing, etc. Filling part 4 and protection part 5
It is also possible to form both at the same time. In this way, the method of forming the filling part 4 and the protection part 5 in one process is effective when the aspect ratio of the through-hole hole 10 is small (shallow compared to the diameter), and is effective when the aspect ratio is large. As described above, it is preferable to form the filling portion 4 and the protection portion 5 in two steps.

The filler-containing printing photoresist forming the filling part 4 and the protection part 5 is covered with the etching resist layer 3 in the etching process of the conductor circuit, and since it does not require much durability against the etching process, the etching resist layer is not required. A photoresist material different from the material in 3 may be used, but if it is a filler-containing printing photoresist that can also be used as an etching resist, it may be the same material as the filling part 4 or protection part 5 and the etching resist layer 3. Filled printing photoresists can also be used.

In the method of this invention, the steps are similar to the above-described ordinary "hole filling method" except for forming the protective part 5 and using filler-containing printing photosyst as the material for the filling part 4 and the protective part 5. In addition to the methods described above, each step can be carried out in combination with a method similar to a normal wiring board manufacturing method.

Next, a specific example in which the method for manufacturing a wiring board with through holes according to the present invention is actually applied will be described.

Example 1 Copper-clad laminate I made of a metal-based insulating substrate in which a metal base material such as iron is coated with epoxy resin or the like and then insulated.
ii slope was used. After forming through-hole holes 10 with a hole diameter of 0.4 mm in this copper-clad laminate by drilling, the through-hole holes 10 were cleaned by sandblasting or the like. Next, after soft etching the surface of the copper-clad laminate and the inner wall surface of the through-hole hole 10 using sulfuric acid, a copper layer is formed using a chemical plating method, and a thick layer of metallic copper is further applied using an electrolytic plating method. , thickness 35
A conductive metal layer 2 of μ was formed.

The inside of the through-hole hole 10 was filled with an ultraviolet curable filler-containing printing photoresist (manufactured by Tamura Kaken Co., Ltd.: negative resist, DER-4200) and dried to form the filled portion 4 . The same photoresist as the filling part 4 was applied by screen printing to the entire surface of the insulating substrate 1 from above the filling part 4 and was dried. The drying temperature at this time is 80
It was ℃. Next, using an appropriate mask, only the through-hole hole 10 and the vicinity of its periphery were exposed to ultraviolet light and developed, thereby hardening the photoresist and forming the protective portion 5.

A negative type photosensitive liquid etching resist (manufactured by Tokyo Ohka Co., Ltd.: Negative type liquid resist, 0P-2) was applied to the entire surface of the insulating substrate 1 on which the protective portion 5 was formed using a roll coater. After drying this etching resist at 80° C., the etching resist is cured by exposing to ultraviolet light using a negative mask pattern and developing. Then, an etching pattern is formed by a conventional method, and the etching resist layer 3 is formed. was formed.

Next, the conductor metal layer 2 was etched using a conventional etching method to form a conductor circuit with a line width and a line spacing of 80 μm. After the etching process was completed, the etching resist layer 3, the protective part 5, and the filling part 4 were all peeled off and removed using a 3% NaOH solution to obtain a wiring board with through holes.

When testing the through-hole conductivity of the wiring board with through-holes manufactured in this way, no defects such as disconnections were found, and the through-hole reliability was extremely high compared to conventional subtractive methods. We were able to prove that.

Example 2 A 96% sintered alumina substrate was used as the insulating substrate l.
- A through-hole hole 10 with a hole diameter of 0.3 mm was formed by laser processing. The surface of this alumina sintered insulating substrate 1 and the inner wall surface of the through hole were uniformly roughened with phosphoric acid. After thoroughly cleaning and drying the roughened insulating substrate 1, the surface of the insulating substrate 1 and the holes 10 for through holes are removed.
A 10 μm thick copper layer was formed on the inner wall surface of the conductive metal layer 2 by chemical plating.

For the insulating substrate 1 on which the conductive metal layer 2 was formed, a filler-containing printing photoresist similar to that in Example 1 was filled into the through-hole holes 10 and simultaneously applied to the entire surface of the insulating substrate 1. . Then, using an appropriate mask, the filling portion 4 and the protection portion 5 were simultaneously formed by exposure to ultraviolet light and development.

Next, using the same filler-containing printing photoresist as the filling part 4 and protection part 5 as an etching resist, it was applied to the entire surface of the insulating substrate 1 by screen printing. After drying this etching resist at 80° C., the etching resist layer 3 is cured by exposing to ultraviolet light using a negative mask pattern and developing it.
A desired etching pattern was formed. Next, a circuit pattern with a line width of 50 μm between lines was formed on the conductive metal layer 2 by etching. After etching, filler 4, protection part 5 and etching resist layer 3 are all removed.
% NaOH solution, and was further degreased and washed with an acidic aqueous solution to obtain a wiring board with through holes.

When the through-hole conductivity of the wiring board with through-holes thus obtained was tested, as in Example 1, no defects such as disconnection were observed, demonstrating that the through-hole reliability was extremely high. Example 3 - 96 parts by weight of AlzOs powder and SiO2, CaO
, MgO, etc., and 12 parts by weight of organic substances (binder, plasticizer, etc.) were added to this mixture, and the whole was further mixed. This mixture was formed into a sheet by a doctor blade method to obtain a ceramic green sheet. This green sheet was heated to a semi-hardened state, and then pressed using a mold to form through-hole holes 10 with a hole diameter of 0.4 man. After drying the above green sheet at 150℃, 1600℃
By firing, an insulating substrate 1 made of a ceramic substrate having holes 10 for through holes was obtained.

After roughening the surface of the insulating substrate 1 with phosphoric acid, a conductive metal layer 2 made of a copper layer with a thickness of 871 m was formed on the substrate surface and the inner wall surface of the through-hole hole 10 by chemical copper plating. Hereinafter, a wiring board with through-holes made of a ceramic substrate was manufactured through the same process as in Example 2. As with each of the above-mentioned Examples, no defects such as disconnection were observed, and excellent through-hole reliability was exhibited. did it.

Example 4 - A wiring board with through holes was manufactured in the same process as in Example 1, except that a glass-based epoxy resin substrate was used as the insulating substrate 1, and a photosensitive liquid etching resist was applied by the dip method. However, as in Example 1, no defects such as wire breakage were observed, and the through-hole reliability was excellent.

Example 5 - A sintered aluminum nitride substrate was used as the insulating substrate 1, a through-hole hole 10 with a hole diameter of 0.3 n+11+ was formed by laser processing, and a photosensitive liquid etching resist was applied with a spinner. When a wiring board with through holes was manufactured in the same process as in Example 1, no defects such as disconnection were observed as in Example 1, and it was confirmed that the board had excellent through hole reliability.

〔Effect of the invention〕

According to the method for manufacturing a wiring board with through-holes according to the present invention as described above, by using a filler-containing printing photoresist as a filler for through-hole holes, volume shrinkage occurs when the filler is cured. This reduces the dents and steps that occur at the periphery of the through-hole.

Furthermore, since the protective portion made of a filler-containing printing photoresist is formed to cover the peripheral edge of the through-hole, there are no dents or steps in the peripheral edge of the through-hole. If there are no dents or steps around the periphery of the through-hole hole, when etching resist is applied, a sufficient thickness of etching resist will adhere to the periphery of the through-hole hole to protect it from the etching process. Etching of the conductive metal layer at the periphery of the through hole can be reliably prevented.

Therefore, the problem of the conventional "hole-filling method" in which the etching resist edge becomes thinner at the periphery of the through-hole hole and the conductive metal layer is etched, causing circuit defects such as disconnections, is solved. Increased reliability. Moreover, since the circuit can be formed using the etching method, similar to the conventional "hole-filling method," the circuit precision is high and the manufacturing cost is low. This means that it is possible to provide an extremely excellent method for manufacturing a wiring board with through holes that can fully satisfy all of the following conditions.

[Brief explanation of the drawing]

FIG. 1 is a process flow chart of an embodiment according to the present invention, FIG. 2 is a sectional view of a wiring board in the middle of the process, and FIG. 3 is a sectional view of a conventional example. 1... Insulating substrate 10... Hole for through hole 11
...Peripheral portion 2...Conductor metal layer 3...Etching resist layer 4...Filled portion 5...Protection Department Patent Attorney Takehiko Matsumoto Figure 1 1. ! J4 cow's 1b = Demand No. 63-299093 2, Name of the invention: Method for manufacturing a wiring board with through holes 3, Compensator Hanyu and the patentee Address: 1048 Kadoma, Kadoma City, Osaka Prefecture
Name (583) Representative of Matsushita Electric Works Co., Ltd. Insert the following sentence between line 18. One statement: ``Moreover, when the etching resist liquid is applied on top of the conventional hole-filling ink 4' as described above, the solvent component in the etching resist and the hole-filling ink 4'' reacts with the hole-filling ink 4', causing melting and peeling of the hole-filling ink 4'.As a result, the resist rrI30 in the portion covering the peripheral portion 11 of the through-hole hole 10 becomes even thinner.'' ■ Specification No. The full text of the action description from page 6, line 19 to page 8, line 3 is corrected as follows: - Statement [Filler-containing photoresists for printing do not react with solvents like conventional heat-curable pore-filling inks. Since the etching resist solution does not melt, even if the etching resist solution is applied on top of the filled printing photoresist that covers the through-hole hole and the surrounding area, there is no need to worry about the filled printing photoresist dissolving or peeling off. However, the thickness of the etching resist layer does not become thinner. By the way, if the through-hole holes are simply filled with a filler-containing printing photoresist and cured, the volumetric shrinkage of the resist will cause some dents or steps at the periphery of the through-hole holes. However, if the periphery of the through-hole hole is
Furthermore, by covering with a filler-containing printing photoresist, the dents and steps can be alleviated. In this way, if the etching resist solution is applied while the inside and peripheral portion of the through-hole hole is covered with the filler-containing printing photoresist, the dents and steps at the peripheral portion of the through-hole hole can be removed as described above. Since it is relaxed by photoresist coating, a sufficiently thick etching resist layer can be formed. Even if the coating thickness of the etching resist layer is thin, a sufficient thickness can be ensured by combining it with a filler-containing printing photoresist that covers the underlying conductive metal layer. Therefore, the conductive metal layer at that location can be reliably protected from the etching process. In this way, the conductive metal layer at the periphery of the through hole can be covered with a sufficiently thick etching resist layer and filler-containing printing photoresist.
The conductive metal layer at this location can be reliably protected from etching. '' ■ In lines 9 and 10 of page 11 of the specification, the statement ``Solvent-based fillers such as pore-filling ink are not preferred'' should be corrected to ``Pore-filling ink and the like are not preferred.'' ■ On page 17, lines 9 to 12 of the specification, the words "through-hole hole 10..., in the case of , if the pore size is large, the above should be corrected. ■ On page 17, lines 17 to 19 of the specification, the phrase "covered with an etching resist layer" has been replaced with "
Since it is covered with an etching resist layer," I corrected it. ■ In the 8th line of page 18 of the specification, the phrase "Photosyst for printing" has been corrected to "Photoresist for printing." ■ In the specification, page 24, line 19 to page 25, line 2, the phrase "by using...also a hole for a through hole" has been corrected to "as well as a hole for a through hole." do. ■ In the 4th line of page 25 of the specification, the phrase ``Because it does, - layer, through hole'' is corrected to ``Because it does, it means through hole.'' ■ On page 25 of the specification, lines 9 and 10, it says “Protect the
The text "through-hole hole" should be corrected as follows. Ichiki-ichi

Claims (1)

[Claims] 1. For an insulated substrate on which a conductive metal layer is formed on the inner wall surface of the through-hole hole and on both sides of the substrate, an etching resist layer with a predetermined pattern is formed on the conductive metal layer of the insulated substrate, and an etching process is performed to form a conductor. In a method of manufacturing a wiring board with through holes for forming a circuit in a metal layer, before forming an etching resist layer, the inside of the through hole hole is filled with a printing photoresist containing filler, and the through hole hole is filled with a printing photoresist containing filler. 1. A method for producing a wiring board with through-holes, the method comprising: covering the peripheral edge of the wiring board with a filler-containing printing photoresist.