JP2007294512A - Manufacturing method for printed-wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed-wiring board having the laminated structure of two metallic layers or more to be used for a high-density wiring board having 100 pins or more inexpensively. <P>SOLUTION: In the printed-wiring board requiring the wirings having a high density of approximately 100 pins or more, copper wirings are formed on the resin surface of a photo-resist board with one-side copper foil for building up two metallic layers or lower of copper-wiring layers at the low cost. That is, a photo resist is exposed and developed, and a desired via pattern is formed in a manufacturing method for a multilayer printed-wiring board forming a conductor pattern composed of at least an electroless copper plating and an electrolytic copper plating on the resin surface of the photo-resist board with one-side copper foil. A photocatalyst compound is further carried on the surface of the photo resist, and exposed in a plated conductor-pattern shape and a difference is set in the wettabilities of metallic-salt solutions as the nuclei of the electroless copper plating in the manufacturing method for the multilayer printed-wiring board. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a printed wiring board capable of supplying an inexpensive multilayer printed wiring board.

In recent years, printed wiring boards have been required to be smaller and lighter, and by adopting structures such as PGA (pin grid array) and BGA (ball grid array) that have been reduced in size and number of pins, wiring has been miniaturized. In addition, it has been required to achieve high density and low cost.
In such a market trend, in order to supply a printed wiring board having a single metal structure at a low price only for a wiring density of about 100 pins or less, the use of an expensive photoresist is reduced to the limit, and the number of processes is reduced. In order to reduce this, a method using a photosensitive resin as an insulating layer has been studied (see, for example, Patent Documents 1 to 3).
This method is characterized by the formation of through-holes by exposure and development processes. Further effects include improved alignment accuracy and large-area batch formation, and mass production of printed circuit boards at a lower cost. Is realized.
However, in such a structure having a photosensitive resin as a core, it is impossible to expose the photosensitive resin that becomes the core, so it is impossible to manufacture a double-sided copper foil-attached substrate by the subtracting method, and about 100 pins The above high-density wiring has a problem that cannot be dealt with.

  On the other hand, the conventional two-metal structure manufacturing process can be roughly divided into two methods. The first method is a pure substruct method. In this method, first, through holes are formed at desired positions on a substrate with a double-sided copper foil, and electroless copper plating and electrolytic copper plating are formed on the through holes, thereby forming conductors that conduct between the front and back copper foils. Further, by aligning with the through-holes, the front and back copper foils are patterned to produce a multilayer printed wiring board having a two-metal structure. Here, as a method for forming this through hole, mechanical processing such as a laser method using laser irradiation, a drilling method, or a punching method using a mold has been put into practical use.

As another method, there is a method of forming a second metal wiring by a semi-additive method on the resin surface of a substrate with a copper foil on one side. This explains a general semi-additive method using a substrate with a single-sided copper foil. First, a laser is applied to the resin layer to form a laser via to the copper foil layer. Further, several thousands of electroless copper plating serving as a seed copper layer is formed on the resin surface of the resin surface and the laser via processed surface. A photoresist is coated on the seed copper layer, exposed and developed to pattern a desired two-metal wiring pattern. Further, electrolytic copper plating is performed to form a copper wiring having a desired film thickness, and then the photoresist that has become a mold is peeled off. Finally, it is a step of forming an independent copper wiring by flash-etching the electroless copper plating exposed on the bottom where the photoresist is stripped.
JP-A-9-260808 Japanese Patent Laid-Open No. 11-258860 JP 2000-141699 A

However, in the substruct method described above, the through-hole formation method has a high running cost and initial cost, requires a long time from design to processing, and requires removal of desmear and cutting waste. For example, it is difficult to supply an inexpensive multilayer printed wiring board.
Moreover, the semi-additive construction method described above is a complicated construction method, and it is difficult to supply an inexpensive multilayer printed wiring board.

  The present invention has been made in order to solve the above-described conventional problems, and an object thereof is, for example, a print having a laminated structure of two or more metal layers on a high-density wiring board of 100 or more pins. It is to provide a wiring board at a low price.

  In order to achieve the above-described problems, the printed wiring board manufacturing method of the present invention is a multilayer printed circuit in which a conductive pattern made of at least electroless copper plating and electrolytic copper plating is formed on the resin surface of a photosensitive resin substrate with a copper foil on one side. A method for producing a wiring board, wherein the photosensitive resin is exposed and developed to form a desired via pattern, and then a photocatalytic compound is supported on the surface of the photosensitive resin and exposed to a conductive pattern to be plated, It is characterized in that a difference is provided in the wettability of the metal salt solution which is the core of electroless copper plating.

  According to the method for producing a printed wiring board according to the present invention, the amount of expensive photoresist used is reduced by half, and the adhesion strength between the resin insulating layer made of a photosensitive resin and the surface in contact with the electroless copper plating film is excellent. A copper wiring pattern made of electrolytic copper plating and electrolytic copper plating can be directly formed, and a high-density multilayer printed wiring board excellent in reliability can be provided easily and inexpensively.

The embodiment of the present invention is a photosensitive resin with a copper foil on one side in order to build up a copper wiring layer of the second metal and later at a low cost in a printed wiring board where the wiring is required to have a high density of about 100 pins or more. The feature is that expensive photoresist is not used (not semi-additive) for the purpose of forming copper wiring on the resin surface of the substrate.
As the photosensitive resin used here, an ultraviolet curable acrylic resin, an ultraviolet curable epoxy resin, or an ultraviolet curable epoxy acrylate having a polymerization structure thereof is used. Alkali development is enabled by a crosslinking reaction with an acid generating additive.
Therefore, the process starts from the step of forming a via using such a chemical reaction. First, an alkaline developer is sprayed to dissolve the unexposed uncrosslinked portion so as to leave a crosslinked portion by exposing the photosensitive resin to expose the copper foil so that the copper foil can be seen from the via.

Here, the present inventor has paid attention to the fact that the present photosensitive resin that has only undergone UV crosslinking has a high moisture absorption rate. Originally, it is UV-crosslinked and completely crosslinked by post-baking the developed photosensitive resin. It has been found that the moisture absorption rate is high because the crosslinking proceeds only by 40 to 50% of the complete crosslinking only by the ultraviolet crosslinking.
In this way, the photosensitive resin that has only been UV-crosslinked is immersed in the photocatalyst compound aqueous solution, the photocatalyst compound hydrolyzed is permeated and supported on the extreme surface of the photosensitive resin, and dehydrated in a hot air oven at about 180 ° C., Titanium oxide is formed. Here, as an example of the aqueous photocatalyst compound solution, an organic titanate (titanium-containing organometallic compound) that easily converts to titanium oxide having a high photoexcitation rate is preferable, and tetraisopropyl titanate, polybutyl titanate, tetra-n-butyl titanate, tetraisopropyl titanate. , Tetra (2-ethylhexyl) titanate, titanium acetylacetonate, titanium tetraacetylacetonate, titanium octylene glycolate, titanium ethylacetoacetate, titanium lactate, titanium triethanolaminate, etc. can be used. is there. In order to improve the photoexcitation rate of titanium oxide, it is also preferable to add a photosensitizer to the aqueous photocatalytic compound solution. Examples of the photosensitizer include water-soluble compounds composed of dyes, organic acids, organic acid salts, and organic amines, and combinations thereof may be used.

Next, the photosensitive resin vias are aligned, exposed to a desired copper wiring pattern, the photocatalyst is excited, and a mist of a metal salt solution (for example, palladium chloride solution) is sprayed, followed by 50 to 90 ° C. Let dry to a degree. Since the exposed and excited locations have good wettability with the aqueous metal salt solution, the desired copper wiring pattern-like palladium on the surface of the photosensitive resin is deposited after drying.
Subsequently, by immersing in an electroless copper plating tank, a patterned seed copper layer having a thickness of several thousand is deposited where palladium is deposited in a copper wiring pattern. Further, the seed copper layer is plated up in an electrolytic copper plating bath to form a copper wiring pattern (second copper wiring pattern) having a desired film thickness.

In addition, the structure described in Claim 1 of this invention is characterized by manufacturing a 2nd copper wiring pattern at the said process, The structure described in Claim 2 is a 2nd copper wiring pattern After forming the film, the photosensitive resin is post-baked at 140 ° C. or higher to promote thermal crosslinking to completely crosslink the photosensitive resin.
When the photosensitive resin is exposed and developed, that is, by supporting the photocatalyst compound before thermally crosslinking the photosensitive resin by heating at 140 ° C. or higher, the photocatalyst compound penetrates the surface of the photosensitive resin better. Thus, the wettability of the metal salt solution can be more effectively differentiated.

If it is post-baked before being immersed in the aqueous photocatalytic compound solution, the photocatalytic compound may be hardly supported. Further, when post-baking immediately after being immersed in the photocatalyst compound aqueous solution, the photocatalyst compound is decomposed, the photocatalytic reaction as expected is not obtained, and palladium is not deposited in the desired copper wiring pattern.
In addition to typical titanium oxide (TiO ₂ ) having a so-called photocatalytic reaction, ZnO, SrTiOP ₃ , CdS, CdO, CaP, InP, In ₂ O ₃ , CaAs, BaTiO ₃ , K ₂ NbO ₃ , Fe ₂ O ₃ , Ta ₂ O ₅ , WO ₃ , NiO, Cu ₂ O, SiC, SiO ₂ , MoS ₃ , InSb, RuO ₂ , CeO _{2 and the} like are known.
Generally, a photocatalytic metal compound generates electrons and holes when irradiated with light, and generates OH and O ²⁻ having a strong oxidizing power by reducing and oxidizing water molecules in the vicinity thereof. For example, when CdSe is irradiated with light, the generated electrons reduce water molecules to generate hydrogen, but holes oxidize themselves instead of oxidizing water molecules, and Cd ²⁺ is eluted. Such a phenomenon is also observed in many other photocatalytic metal compounds.
However, titanium oxide is specific as a photocatalytic metal compound that does not cause a self-elution phenomenon, and therefore titanium oxide is most useful as a photocatalyst. Initially, we considered adding fine particles of titanium oxide as a filler directly to the photosensitive resin, but the patternability during via development has deteriorated and the adhesion between the photosensitive resin and the first copper foil Various problems occur, such as lowering.

Moreover, the structure of Claim 3 and Claim 4 of this invention uses the aqueous solution of a titanium containing organometallic compound in view of requiring a photocatalyst only for the surface of the photosensitive resin in which the via | veer was formed. It is characterized in that the exposed portion is photoexcited and wettability is improved.
The exposed portion is photoexcited as described above, and the palladium chloride aqueous solution mist adheres to the portion with improved wettability. When this is dried, the palladium used as a catalyst for electroless copper plating is patterned. In addition, the structure of Claim 5 of this invention is characterized by forming a copper wiring continuously with electroless copper plating and electrolytic copper plating in this way.
Also, here, the method of forming a through hole at a desired position on a conventional double-sided copper foil substrate and forming a conductor between the front and back copper foils in the through hole absorbs the misalignment between the through hole and the copper foil wiring. Therefore, in general, a land having a radius about 0.1 mm larger than that of the through hole is required. For this reason, although it depends on the number of pins, the degree of freedom in designing the number of wirings between the lands of the through holes is improved.

Hereinafter, the manufacturing method of the multilayer printed wiring board of this invention is demonstrated concretely using drawing.
Here, the formation method of the 2nd copper wiring pattern formed in the resin surface is demonstrated in detail.
1 and 2 are sectional views showing a second wiring pattern configuration and its manufacturing process according to the first embodiment of the present invention.
First, as a photosensitive resin material, 52 parts by weight of bisphenol A type epoxy acrylate (Lipoxy VR-90; manufactured by Showa Polymer Co., Ltd.) and 15 parts by weight of phthalic anhydride were stirred in propylene glycol monomethyl ether acetate solvent at 110 ° C. for 30 minutes. Thus, an alkali development type photosensitive resin varnish raw material was prepared.
Furthermore, 50 parts by weight (solid content) of the alkali development type photosensitive resin varnish raw material, 17 parts by weight of an alicyclic epoxy compound (EHPE3150; manufactured by Daicel Chemical Industries), a photocurable epoxy resin (Cyclomer M100; Daicel Chemical). 30 parts by weight), 3 parts by weight of a photoinitiator (Lucirin TPO; manufactured by BASF), a propylene glycol monomethyl ether acetate solvent is added and dispersed in a continuous horizontal sand mill for about 3 hours to obtain an alkali developing photosensitive resin. A varnish was prepared.
On the first copper foil (steps [1a] and 1a2), the alkali-developable photosensitive resin varnish is applied with a slit coater, dried at 70 ° C. for 20 minutes, and B-shaped photosensitive film having a thickness of about 25 μm. Resin (1a1) was formed. A 19 μm-thick PET film (1a3) was bonded to the surface of the B-stage-like photosensitive resin (1a1) to form a photosensitive resin substrate with one side copper foil.

A photomask on which a φ200 μm via pattern was drawn was brought into intimate contact with the photosensitive resin surface of the photosensitive resin substrate with a copper foil on one side, and was exposed to light at 500 mJ / cm ² with an ultrahigh pressure mercury lamp for photocrosslinking. Next, after separating a PET film having a thickness of 19 μm, developing with about 5% organic amine alkaline aqueous solution, washing with water, sufficiently drying in a hot air oven at 90 ° C., and a resin substrate with one side copper foil having a via of about 200 μm (Steps [1b] and 1b1) were formed.
Next, after immersing and adsorbing a resin substrate with a copper foil on one side in a tetraisopropyl titanate aqueous solution (5% aqueous solution) at room temperature, it is post-baked in a hot air oven at 180 ° C. for about 1 hour. The uncrosslinked portion of the resin is completely thermally crosslinked (steps [1c] and 1c1). Also, post-baking causes the hydrolyzed tetraisopropyl titanate to undergo a dehydration reaction, thereby precipitating titanium oxide (steps [1c] and 1c4).
Further, a photomask (1d6) on which a desired second copper wiring pattern was drawn was aligned and brought into close contact with the via pattern, and was exposed to 500 mJ / cm ² with an ultrahigh pressure mercury lamp (1d7) (step [1d]).

After this exposure, a palladium catalyst solution obtained by diluting 0.6 g of palladium chloride and 1 mL of hydrochloric acid with 1 L of ion-exchanged water was sprayed with a two-fluid spray device. Here, the portion (1d4) previously exposed in the second copper wiring pattern is photoexcited, and the palladium catalyst solution is still applied in the second copper wiring pattern, and a hot temperature of 120 ° C. The plate was sufficiently dried (step [1e]).
A resin substrate with one-sided copper foil supporting an activated palladium catalyst (1e8) is immersed in an electroless copper plating bath for about 10 minutes, and an electroless copper plating film having a thickness of about 0.5 μm (step [1f], 1f9) was formed. As the electroless copper plating bath, a 0.02 mol / dm ³ Cu (II) -EDTA bath using formaldehyde as a reducing agent was used.
After removing the palladium catalyst with 100 g / L dilute hydrochloric acid, electrolytic copper plating was performed for about 30 minutes to form a second copper wiring pattern having a thickness of about 12 μm on the resin surface of the resin substrate with one side copper foil (step [ 1g], 1g10). The electrolytic copper plating bath used was a 0.1 mol / dm ³ Cu (II) -EDTA bath.
Through the above steps, a second copper wiring pattern used for the multilayer printed wiring board of the present invention was obtained.

The copper wiring pattern was immersed in a solder bath (260 ° C.) for about 20 seconds, but no change was observed. A peel test pattern having a width of 1 cm was prepared based on JIS-C6481, and the peel strength measured by a 90-degree peel test was about 1.2 kg / cm.
The insulation resistance test (PCBT) is performed on the interlayer pattern using the counter electrode pattern of JIS-C6481 in the pressure cooker (PCT), and the change in the insulation resistance value after 100 hours is applied voltage 25V, 120 ° C, 85%. It was confirmed that it was within 10% and there was no problem.

Next, a simple process flow is shown in FIG. 3, and a method for manufacturing a multilayer printed wiring board will be described.
First, an alkali development type photosensitive resin solution was prepared in the same manner as in Example 1.
As a photosensitive resin material, 52 parts by weight of bisphenol A type epoxy acrylate (Lipoxy VR-90; manufactured by Showa Polymer Co., Ltd.) and 15 parts by weight of phthalic anhydride were stirred in propylene glycol monomethyl ether acetate solvent at 110 ° C. for 30 minutes. Thus, an alkali development type photosensitive resin varnish raw material was prepared.
Furthermore, 50 parts by weight (solid content) of the alkali development type photosensitive resin varnish raw material, 17 parts by weight of an alicyclic epoxy compound (EHPE3150; manufactured by Daicel Chemical Industries), a photocurable epoxy resin (Cyclomer M100; Daicel Chemical). 30 parts by weight), 3 parts by weight of a photoinitiator (Lucirin TPO; manufactured by BASF), a propylene glycol monomethyl ether acetate solvent is added and dispersed in a continuous horizontal sand mill for about 3 hours to obtain an alkali developing photosensitive resin. A varnish was prepared.
On the first copper foil, the alkali development type photosensitive resin varnish was applied with a slit coater and dried at 70 ° C. for 20 minutes to form a photosensitive resin layer having a thickness of about 25 μm. A 19 μm-thick PET film was bonded to the surface of the B-stage-like photosensitive resin layer to form a photosensitive resin substrate with one side copper foil (S1).

A negative photoresist solution (PVA (polyvinyl alcohol) aqueous solution using potassium dichromate as a photosensitizer) was roll-coated on the copper foil surface of the photosensitive resin substrate with one side copper foil to form a photoresist film ( S2). Moreover, the photomask by which the 1st copper wiring pattern was drawn on the photoresist surface on the copper foil of the photosensitive resin substrate with one side copper foil is desired on the photosensitive resin surface of the photosensitive resin substrate with one side copper foil. The photomask on which the via pattern is drawn is aligned with the two photomasks and brought into close contact with the photosensitive resin substrate with copper foil coated with the photoresist, and an exposure amount of 500 mJ / cm ² is applied to the ultrahigh pressure mercury lamp. Were subjected to double-sided batch exposure to photocrosslink desired portions of the photoresist film and the photosensitive resin.
Subsequently, it was developed with about 5% organic amine alkali aqueous solution, washed with water, and sufficiently dried in a hot air oven at 90 ° C. On the copper foil surface, a PVA photoresist film was formed in the shape of a first copper wiring pattern, and on the photosensitive resin, a resin substrate with a copper foil on one side formed with a photoresist film having a via of about 200 μm was formed. (S3).
Here, in order to protect the photoresist film, a polypropylene film with an adhesive (Hitalex L-3320; manufactured by Hitachi Chemical Co., Ltd.) was pasted on the photoresist film using a roll laminator (S4).

Next, after immersing and adsorbing a resin substrate with a copper foil on one side in a tetraisopropyl titanate aqueous solution (5% aqueous solution) at room temperature, it is post-baked in a hot air oven at 180 ° C. for about 1 hour. The uncrosslinked portion of the resin is completely thermally crosslinked (S5, S6). In addition, by post-baking, the hydrolyzed tetraisopropyl titanate is dehydrated to precipitate titanium oxide.
Further, a photomask on which a desired second copper wiring pattern was drawn was aligned and brought into close contact with the via pattern, and was exposed to 500 mJ / cm ² with an ultrahigh pressure mercury lamp (S7). After the exposure, a palladium catalyst solution obtained by diluting 0.6 g of palladium chloride and 1 mL of hydrochloric acid with 1 L of ion-exchanged water was sprayed with a two-fluid spray device (S8). Here, the portion exposed in the second copper wiring pattern is photoexcited, and this palladium catalyst solution is sufficiently dried on a hot plate at 120 ° C. while being applied in the second copper wiring pattern. I let you.

The resin substrate with one-sided copper foil supporting the activated palladium catalyst was immersed in an electroless copper plating bath for about 10 minutes to form an electroless copper plating film having a thickness of about 0.5 μm (S9). As the electroless copper plating bath, a 0.02 mol / dm ³ Cu (II) -EDTA bath using formaldehyde as a reducing agent was used. After removing the palladium catalyst with 100 g / L dilute hydrochloric acid, electrolytic copper plating was performed for about 30 minutes to form a second copper wiring pattern having a thickness of about 12 μm on the resin surface of the resin substrate with one side copper foil (S10, S11). The electrolytic copper plating bath used was a 0.1 mol / dm ³ Cu (II) -EDTA bath.
Furthermore, in order to protect this second copper wiring pattern from copper foil etching, a polypropylene film with adhesive (Hitalex L-3320; manufactured by Hitachi Chemical Co., Ltd.) was pasted on the photoresist film using a roll laminator (S12). . Subsequently, after removing the polypropylene film that protected the photoresist film on the copper foil (S13), ferric chloride solution (50 ° C, density 1.450 g / cm ³ ) was sprayed to etch the copper foil. Next, the PVA photoresist was stripped with a 10% potassium hydroxide stripping solution at 80 ° C. to form a first copper wiring pattern (S15).
Here, after removing the polypropylene film protecting the second copper wiring pattern, it was post-baked in a hot air oven at 180 ° C. for about 1 hour to completely thermally crosslink the uncrosslinked portion of the photosensitive resin (S16). ).

Further, a photosensitive solder resist ink (PFR-800 FLX201Y; manufactured by Taiyo Ink Manufacturing Co., Ltd.) is screen-printed on a resin substrate (S17), pre-baked at 90 ° C., and aligned, and a photomask is closely exposed. Next, development is performed with an organic alkali developer at 30 ° C. so that the external connection terminal portion is exposed (S18). This step is performed using photomasks with different patterns.
Further, electrolytic nickel plating and electrolytic gold plating are performed (S19). An electrolytic nickel plating bath, an electrolytic gold plating bath, and the like may be generally well known.
Through the above steps, a multilayer printed wiring board according to the present invention was obtained, wherein the first copper wiring pattern was manufactured by a substruct method, and the second copper wiring pattern was manufactured by an additive method.

<Comparative Example 1> Here, a method of forming a second copper wiring pattern by a commonly used semi-additive method will be described.
4 to 6 are sectional views showing a second wiring pattern configuration and a manufacturing process thereof according to a comparative example.
First, as a photosensitive resin material, 52 parts by weight of bisphenol A type epoxy acrylate (Lipoxy VR-90; manufactured by Showa Polymer Co., Ltd.) and 15 parts by weight of phthalic anhydride were stirred in propylene glycol monomethyl ether acetate solvent at 110 ° C. for 30 minutes. Thus, an alkali development type photosensitive resin varnish raw material was prepared.
Furthermore, 50 parts by weight (solid content) of the alkali developing photosensitive resin varnish raw material, 17 parts by weight of an alicyclic epoxy compound (EHPE3150; manufactured by Daicel Chemical Industries), a photocurable epoxy resin (Cyclomer M100; Daicel Chemical) 30 parts by weight), 3 parts by weight of a photoinitiator (Lucirin TPO; manufactured by BASF), a propylene glycol monomethyl ether acetate solvent is added and dispersed in a continuous horizontal sand mill for about 3 hours to obtain an alkali developing photosensitive resin. A varnish was prepared.
On the first copper foil (steps [3a] and 3a2), the alkali-developable photosensitive resin varnish is applied with a slit coater, dried at 70 ° C. for 20 minutes, and photosensitive resin (3a1 having a thickness of about 25 μm). ) Was formed. A 19 μm-thick PET film (3a3) was bonded to the surface of the B-stage photosensitive resin to form a photosensitive resin substrate with one side copper foil.

A photomask on which a desired via pattern was drawn was brought into close contact with the photosensitive resin surface of the photosensitive resin substrate with a copper foil on one side, and was exposed to light at 500 mJ / cm ² with an ultrahigh pressure mercury lamp for photocrosslinking. Next, after separating a PET film having a thickness of 19 μm, developing with about 5% organic amine alkaline aqueous solution, washing with water, sufficiently drying in a hot air oven at 90 ° C., and a resin substrate with one side copper foil having a via of about 200 μm Was formed (step [3b]).
Next, in order to support the palladium catalyst on the surface of the photosensitive resin, it was immersed in a catalyst bath composed of palladium chloride and tin chloride solution to support the palladium-tin colloid on the surface of the photosensitive resin. In the next accelerator bath, at the same time as the removal of tin, palladium particles (3c4) are fixed to the surface of the photosensitive resin (step [3c]). The fixed palladium particles are supported as a catalyst, and a resin substrate with one side copper foil is immersed in an electroless copper plating bath for about 10 minutes to form an electroless copper plating film (3d5) having a thickness of about 0.5 μm (process) [3d]). As the electroless copper plating bath, a 0.02 mol / dm ³ Cu (II) -EDTA bath using formaldehyde as a reducing agent was used.

Here, after removing the palladium catalyst with dilute hydrochloric acid of 100 g / L, a negative photoresist (PMER; manufactured by Tokyo Ohka Kogyo Co., Ltd.) (3e6) was roll-coated on the electroless copper plating film by 90 °. Pre-baked with C. It is exposed at 200 mJ / cm ² through a photomask (3f7) of the desired second copper wiring pattern (step [3f]), developed with an organic alkaline aqueous solution, and a frame of the desired second copper wiring pattern ( 3g6) was formed (step [3g]).
Furthermore, in order to prevent electrolytic copper plating from being deposited on the surface of the first copper foil, a polypropylene film with an adhesive (Hitalex L-3320; manufactured by Hitachi Chemical) is used on the surface of the first copper foil using a roll laminator. pasted. Thereafter, electrolytic copper plating was performed for about 30 minutes to form a copper foil (3h9) having a thickness of about 12 μm on the resin surface of the resin substrate with one side copper foil and the first copper foil exposed from the via (step [3h ]). The electrolytic copper plating bath used was a 0.1 mol / dm ³ Cu (II) -EDTA bath.
Furthermore, the negative photoresist was dissolved and stripped with 10% sodium hydroxide stripping solution at 80 ° C. (step [3i]).
Next, a second copper wiring pattern was formed by flash-etching the electroless copper plating portion exposed from the stripped negative photoresist trace (step [3j]).
The second copper wiring pattern used for the multilayer printed wiring board can be obtained by the general semi-additive process as described above. However, this method requires a considerable number of processes such as a process that requires an expensive alkali-dissolving photoresist and a flash etching process that etches unnecessary electroless plating. Therefore, it is difficult to supply an inexpensive multilayer printed wiring board to the market due to a decrease in yield and an increase in material costs.

It is sectional drawing which shows the 2nd wiring pattern structure by Example 1 of this invention, and its manufacturing process. It is sectional drawing which shows the 2nd wiring pattern structure by Example 1 of this invention, and its manufacturing process. It is a process flowchart figure of the multilayer printed wiring board by Example 2 of this invention. It is sectional drawing which shows the 2nd wiring pattern structure by the comparative example, and its manufacturing process. It is sectional drawing which shows the 2nd wiring pattern structure by the comparative example, and its manufacturing process. It is sectional drawing which shows the 2nd wiring pattern structure by the comparative example, and its manufacturing process.

Explanation of symbols

1a1 ... B-stage photosensitive resin, 1a2 ... first copper foil layer, 1a3 ... PET separator, 1b1 ... photocrosslinked photosensitive resin, 1c1 ... photothermal crosslinked photosensitive resin, 1c4 ... titanium oxide 1d4 …… Excited titanium oxide, 1d5 …… Unexcited titanium oxide, 1d6 …… Photomask with second copper wiring pattern, 1d7 …… UV, 1e8 …… Palladium catalyst, 1f9 …… Electroless copper Plating, 1g10 …… Electrolytic copper plating, 1g11 …… Counter electrode for electrolytic copper plating.

Claims (6)

On the resin surface of the photosensitive resin substrate with copper foil on one side, a method for producing a multilayer printed wiring board that forms a conductive pattern consisting of at least electroless copper plating and electrolytic copper plating,
After exposing and developing the photosensitive resin to form a desired via pattern, a photocatalytic compound is supported on the surface of the photosensitive resin, exposed to a conductive pattern to be plated, and becomes a core of electroless copper plating Make a difference in the wettability of the salt solution,
A printed wiring board manufacturing method characterized by the above.   The method for producing a printed wiring board according to claim 1, wherein the photocatalytic compound is supported before the photosensitive resin is thermally crosslinked by heating at 140 ° C. or higher.   The method for producing a printed wiring board according to claim 1, wherein the photocatalytic compound is a titanium-containing organometallic compound.   The method for producing a printed wiring board according to any one of claims 1 to 3, wherein the photocatalyst compound is excited by exposure to ultraviolet rays to improve the wettability of the metal salt solution.   The metal salt solution includes at least a palladium salt solution, a seed copper layer is formed as a nucleus of electroless copper plating, and a conductor pattern is further formed by electrolytic copper plating. 5. The method for producing a printed wiring board according to any one of 4 above. 6. The printed wiring board according to claim 5, wherein the photosensitive resin is an ultraviolet curable epoxy acrylate, the photocatalytic compound is tetraisopropyl titanate, and the palladium salt solution is palladium chloride. Production method.

Images