JP2630193B2 - Copper-clad insulation sheet for printed wiring boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-clad insulating sheet for manufacturing a multilayer printed wiring board suitable for high-density mounting. In particular, to provide a copper-clad insulating sheet capable of being manufactured with excellent mass productivity of a multilayer printed wiring board having excellent blind via holes and through via holes such as physical properties and electrical properties, particularly having a through hole in advance. The present invention relates to a copper-clad insulating sheet suitable for producing a multilayer printed wiring board using an inner panel.

[0002]

2. Description of the Related Art As electronic devices have become smaller and more multifunctional,
Currently, printed wiring boards are moving toward higher densities. For example, thinner conductor circuits, higher multilayers, smaller via holes including interstitial via holes such as through via holes, blind via holes, and barrier via holes, and smaller chip parts. There is high-density mounting by surface mounting.

In order to explain a conventional method for manufacturing a multilayer wiring board having blind via holes, FIGS. 11 to 19 show schematic cross sections of respective steps. As shown in FIG. 11, an inner layer panel 7 in which a copper wiring pattern 6 is formed in advance by the etch method is prepared, and one or two prepregs 5 are stacked between the outer layer copper foil 1 and the inner layer panel 7. By laying up and hot pressing, a copper clad laminate panel having an inner layer wiring pattern shown in FIG. 12 is obtained.

[0004] Next, holes are formed sequentially at predetermined positions by a drill machine to form blind via hole holes 13, as shown in FIG. 13. Subsequently, if a conventional through via hole 10 is provided, the result is as shown in FIG.

Hereinafter, conventional electroless copper plating and electrolytic copper plating are performed to form plated through holes 11 as shown in FIG.
After the etching resist 12 is formed (FIG. 16), the etching is continued, as shown in FIG. 17, and finally the etching resist film is stripped to have a blind via hole as shown in FIG. A multilayer printed wiring board is obtained. When a solder resist is further formed, the result is as shown in FIG.

However, in order to form a blind via hole with a drill as described above, it is not possible to form a plurality of panels by stacking them as in a normal through hole, and it is necessary to make holes one by one. There is a disadvantage that it takes a very long time and production efficiency is poor. Further, in drilling, in order to control the depth of the tip of the drill, it is necessary to match the moving distance in the drilling direction, generally the Z-axis direction, with the depth of the copper wiring pattern on the surface of the inner layer panel. . However, as described above, 0.1 to 0.
Drills with a small diameter of about 5 mm have large runout, and there are variations in the position of the copper wiring pattern in the Z-axis direction. Therefore, it is difficult to control with high accuracy. If the drilling is shallow, it will not reach the lower copper wiring pattern. However, it is not connected by plating in a later step and causes a blind via hole defect. Conversely, if the drilling is too deep, it may come into contact with a copper foil pattern thereunder, resulting in a short circuit defect.

As the prepreg, those obtained by impregnating a glass fiber with a resin are mainly used. However, when electricity is supplied to a conductor circuit of a printed wiring board in which the glass fiber and the conductor are brought into contact with or in proximity to each other, the glass fiber becomes It is known that a phenomenon called CAF (Conductive Anodic Filament) in which a conductor grows along occurs and causes a deterioration of insulation.
A major problem has been how to prevent insulation deterioration due to CAF of a printed circuit board when the conductor gap and the through-hole gap are extremely small in high-density wiring.

In order to solve these disadvantages of the conventional method, the present inventors have already completed a method of manufacturing a multilayer printed wiring board which is completely different from the conventional method (Japanese Patent Application No. 4-56347).
issue). This invention heat-laminates the insulating layer side of a copper-clad insulating sheet composed of an insulating layer and an outer layer conductor on an inner layer panel having a conductor pattern such as copper foil, forms a conductor pattern on the outer layer conductor, After the copper foil at the position where the via hole is to be formed is removed by etching, the exposed resin layer is dissolved in alkali to expose the conductor pattern of the inner layer panel, thereby forming a blind via hole or an access hole. Is formed, and the conductive pattern of the inner layer panel and the conductive pattern of the outer layer are electrically connected by a conductive paste or plating.

[0009]

However, in the above manufacturing method, in order to form an access hole-shaped through via hole using an inner layer panel having no through hole, a copper-clad insulating sheet is laminated on the inner layer panel. Thereafter, a blind via hole is provided, and a through hole is subsequently formed by a drill. In this case, even if a drilling plate such as aluminum or an insulating substrate is used, a space is generated in a drill hole portion, and burrs of copper foil are generated. Since it is difficult to remove the burrs, stress is concentrated on the burrs at the time of imparting conductivity to the through-holes with a conductive paste or plating, and cracks are generated.

As an improvement, a method of laminating the above-mentioned copper-clad insulating sheet using an inner layer panel provided with through holes in advance has been considered. However, in this case, the resin of the copper-clad insulating sheet flows into the through-hole, and the through-hole is completely filled with the resin. After the surface copper foil at the position where the blind via hole is to be formed is removed by etching, it is exposed. When dissolving the resin layer with alkali under the optimal conditions, the resin that flows into the through-hole of the access hole shape is incompletely dissolved and conversely, if the resin in the through hole is completely dissolved, the inner layer The resin around the blind via hole, which forms the layer between the conductive pattern of the panel and the outer conductor, dissolves excessively, the undercut progresses, and the resin dissolves more than the land part of the inner layer conductor pattern. There is a drawback that the insulation between the conductor and the conductor on the inner layer panel cannot be obtained.

The present invention eliminates the drawbacks of the above-mentioned method, makes it possible to produce a multilayer printed wiring board having blind via holes and through via holes which are excellent in physical and electrical properties, stable in quality and excellent in mass productivity. A copper-clad insulating sheet is provided.

The blind via hole is a hole for electrically connecting two layers of conductive patterns, and the access hole-like through via hole is a hole for electrically connecting three or more layers of conductive patterns. The reason for forming an access hole in order to connect multiple layers is to increase the contact area between the conductive paste and the conductive pattern of plating and to secure electrical connection reliability.

[0013]

In some of the copper-clad insulating sheets of the present invention, a layer of the first resin composition which is soluble in an alkaline aqueous solution and has low fluidity during heating is formed by roughening copper foil. And a second layer having a higher solubility in an aqueous alkaline solution than the first resin composition and a higher fluidity during heating.
By forming a layer of the resin composition.

Here, "high fluidity at the time of heating" means that the resin composition side of the copper-clad insulating sheet is superimposed on the surface of the inner layer panel, and the heating in the step of laminating the whole by pressing or laminating, ie, approximately 60%. In the range of -100 ° C, it means that the resin composition can be melted and easily flow into the conductive pattern of the inner layer panel to fill the concave portions of the pattern.

The difference between the solubility of the first and second resin compositions in the aqueous alkali solution in the copper-clad insulating sheet is due to the difference in the solubility of these resin compositions to form blind via holes. It is expressed by a relative evaluation of the melting time of each of the first resin composition and the second resin composition. That is, when dissolving the layer of the first resin composition and the layer of the second resin composition under the same conditions, for example, at about 30 to 40 ° C. and using 1% by weight of sodium carbonate, under such conditions, The second resin composition must have a higher solubility in an aqueous alkaline solution than the first resin composition.

When the dissolving conditions of the respective layers are different, for example, under the condition that the first resin composition and the second resin composition are dissolved in aqueous alkali solutions having different concentrations or temperatures, the respective resin layers have different concentrations or temperatures. In contrast to the solubility of each resin composition in an aqueous alkaline solution, the second resin composition needs to have higher solubility than the first resin composition. More specifically, as compared with the solubility of the first resin composition in an aqueous alkali solution at a certain liquid temperature, the second resin composition has a higher solubility in an aqueous alkali solution at a lower liquid temperature. If it has, it is still good. Thus, the relative solubility of the first resin composition and the second resin composition changes according to the dissolution conditions.

On the other hand, the present inventors have found that when the acid value of the base resin is changed, the range in which the dissolution time of the resin composition is minimized changes depending on the concentration of the aqueous alkali solution, for example, the aqueous sodium carbonate solution. That is, if the acid value of the base resin is large, the best range of the solubility of the resin composition,
If the acid value is small, the concentration becomes extremely narrow on the low concentration alkali side, and if the acid value is small, the concentration becomes almost insoluble. A copper-clad insulating sheet that makes use of this property and reduces the acid value of the base resin of the first resin composition and increases the acid value of the second resin composition can also achieve the object of the present invention. Become. That is, when dissolving the layer of the first resin composition, reduce the concentration of the aqueous sodium carbonate solution,
When dissolving the layer of the second resin composition, the layer of the second resin composition can be intensively dissolved by increasing the concentration of the aqueous solution of sodium carbonate. On this occasion,
A relatively high-temperature and low-concentration aqueous sodium carbonate solution is used when dissolving the first resin composition layer, and a relatively low-temperature and high-concentration sodium carbonate aqueous solution is used when dissolving the second resin composition layer. May be.

In the copper-clad insulating sheet of the present invention, the first and second resin composition layers are made of a base resin soluble in an aqueous alkaline solution (hereinafter simply referred to as “base resin”).
And, depending on the type and purpose, obtained by blending necessary components selected from an adhesive reinforcing agent (crosslinking agent), an active energy ray curing reaction initiator, an active energy ray curing reaction accelerator and a curing agent. . Further, a coloring pigment, a moisture-resistant pigment, an antifoaming agent, a leveling agent, a thixotropy-imparting agent, a polymerization inhibitor or an anti-settling agent may be appropriately added.

As the base resin, a carboxyl group,
A non-photosensitive resin containing an alkali-soluble group such as a phenolic hydroxyl group or an alkali-soluble group such as a carboxyl group or a phenolic hydroxyl group and an acryloyl group or a methacryloyl group (hereinafter referred to as “(meth) acryloyl group”) .), A photosensitive resin containing a photopolymerizable or photodimerizable photosensitive group such as an internal olefin, an azide group, and a cinnamate residue.

Examples of the non-photosensitive resin include a copolymer of acrylic acid or methacrylic acid (hereinafter referred to as “(meth) acrylic acid”) and a vinyl monomer such as (meth) acrylic acid ester or styrene; A half ester obtained by adding an alcohol to a copolymer of styrene and maleic anhydride (SMA1440, STO
MA17352, SMA2625, SMA3840 and M
ONSANTO SCRIPSET540, SCRI
PSET550 etc.), copolymer of styrene and p-hydroxyphenylmaleimide, polyvinylphenol (Marukalinker M, Marukalinker MB, etc., manufactured by Maruzen Petrochemical Co., Ltd.) or polyvinylphenol with methyl methacrylate, hydroxyethyl methacrylate, styrene ,
Copolymers with phenylmaleimide and the like, novolak-type phenol resins, novolak-type cresol resins, ring-opened adducts of alcoholic hydroxyl group-containing polymers and acid anhydrides, and the like can be used. When a polyfunctional monomer is added to the resin, photosensitivity can be imparted.

As the base resin, a resin having photosensitivity is preferable.
The range is preferably 0.0 meq / g, more preferably 0.3 to 8.0 meq / g, and particularly preferably 0.5 to 8.0 meq / g.
It is 5.0 meq / g. If the concentration of the photosensitive group is too low, the photocurability deteriorates, and if it is too high, the storage stability deteriorates.

Examples of the resin having photosensitivity include epoxy acrylate and / or methacrylate (hereinafter, “acrylate and / or methacrylate” is referred to as “(meth) acrylate”), a ring-opening adduct of an acid anhydride, and styrene. Half ester obtained by adding unsaturated alcohol to copolymer of maleic anhydride, copolymer of vinyl monomer such as (meth) acrylic acid and (meth) acrylate or styrene, copolymer of styrene and maleic anhydride Ring-opening of half ester with alcohol added to it, copolymer of styrene and p-hydroxyphenylmaleimide, polyvinylphenol or its copolymer, novolak phenol resin, novolak cresol resin, alcoholic hydroxyl group-containing polymer and acid anhydride Various polymers such as adducts , Glycidyl (meth)
Ring-opening adducts with glycidyl group-containing unsaturated compounds such as acrylates (hereinafter collectively referred to as "ring-opening adducts of polymers with glycidyl group-containing unsaturated compounds"), styrene and p
(Meth) acrylic acid chloride, cinnamic acid, a part of the hydroxyl group in a phenolic hydroxyl group-containing polymer such as a copolymer of hydroxyphenylmaleimide, polyvinylphenol or a copolymer thereof, a novolak-type phenol resin, and a novolak-type cresol resin. What has been subjected to a condensation reaction of a photosensitive group-containing acid chloride such as chloride, a part of the hydroxyl group of an alcoholic hydroxyl group-containing polymer, (meth) acrylic acid chloride, condensed with a photosensitive group-containing acid chloride such as cinnamic acid chloride, A ring-opening addition of an acid anhydride to the remaining hydroxyl groups, an isocyanate group-containing (meth) acrylate was added to some of the hydroxyl groups of the alcoholic hydroxyl group-containing polymer, and the acid anhydride was ring-opened to the remaining hydroxyl groups. , A copolymer of styrene and p-hydroxyphenylmaleimide, A polymer obtained by adding an isocyanate group-containing (meth) acrylate to a part of hydroxyl groups in a phenolic hydroxyl group-containing polymer such as a vinyl phenol or a copolymer thereof, a novolak type phenol resin, a novolak type cresol resin, epoxy (meth) Examples thereof include those obtained by adding an isocyanate group-containing (meth) acrylate to some of the hydroxyl groups of an acrylate and ring-opening addition of an acid anhydride to all or a part of the remaining hydroxyl groups.

These manufacturing methods are, for example, as follows. A half ester obtained by adding an unsaturated alcohol to a copolymer of styrene and maleic anhydride can be obtained by adding an unsaturated alcohol such as hydroxyethyl (meth) acrylate to a copolymer of styrene and maleic anhydride. Can be.

The ring-opening adduct of the polymer with the unsaturated compound containing a glycidyl group may be a solvent (eg, ethers such as diglyme, esters such as ethyl carbitol acetate, ethyl cellosolve acetate, isopropyl acetate, ketones such as methyl ethyl ketone and cyclohexanone). And glycidyl (meth) acrylate as it is or by diluting it with a solvent and reacting it dropwise.

At this time, a radical polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, phenothiazine and the like is preferably used in an amount of 10 to 10,000 ppm, more preferably 30 to 5,000 ppm, and most preferably 50 to 5,000 ppm.
2,000 ppm, the reaction temperature is preferably from room temperature to 170 ° C, more preferably from 40 to 150 ° C,
Most preferably, it is performed in the range of 60 to 130 ° C. It is preferable to add a quaternary ammonium salt such as tetrabutylammonium bromide or trimethylbenzylammonium chloride, a tertiary amine such as triethylamine, or the like as a catalyst. When the epoxy group of glycidyl (meth) acrylate is ring-opened to an alkali-soluble group such as a carboxyl group or a phenolic hydroxyl group in a polymer,
If a suitable acid value is obtained by leaving a part of the alkali-soluble group, it can be used as it is. When the acid value becomes too small and the alkali solubility decreases, the acid value can be increased by ring-opening addition of an acid anhydride to the secondary hydroxyl group generated in the above reaction.

Part of the hydroxyl groups in a phenolic hydroxyl group-containing polymer such as a copolymer of styrene and p-hydroxyphenylmaleimide, polyvinylphenol or a copolymer thereof, a novolak-type phenol resin, a novolak-type cresol resin, and (meth) The synthesis of a product obtained by subjecting a photosensitive group-containing acid chloride such as acrylic acid chloride and cinnamic acid chloride to a condensation reaction is as follows. Solvents (methylene chloride, chloroform, toluene and other water-immiscible solvents,
Or a water-miscible solvent such as acetone, diglyme, ethyl carbitol acetate), dissolving a phenolic hydroxyl group-containing polymer, and adding a basic compound such as sodium hydroxide, potassium hydroxide, calcium hydroxide or triethylamine, or a photosensitive group-containing acid. It is obtained by adding chloride and reacting at a reaction temperature of usually 0 to 100 ° C (preferably 0 to 50 ° C, more preferably 0 to 30 ° C). As a catalyst, a quaternary ammonium salt, a tertiary amine, a phosphoric ester, a phosphite, or the like may be used. When a water-immiscible solvent is used and an inorganic base is used, the reaction may be terminated quickly by adding water to the system.

In the purification, when a water-immiscible solvent is used, the reaction solution is washed with an acidic aqueous solution, then washed with water repeatedly, dehydrated and filtered. Further, the solvent after the removal is desolvated or, if necessary, subjected to reprecipitation purification. If a water-miscible solvent is used, the reaction solution is mixed with an appropriate amount of water to precipitate the product as a solid. After repeated washing with water, it is dried. When condensing the phenolic hydroxyl group, which is an alkali-soluble group in the polymer, with an acid chloride group, an appropriate acid value is obtained while leaving a part of the alkali-soluble group.

The isocyanate group-containing (meth) acrylate is added to a part of the hydroxyl groups of the alcoholic hydroxyl group-containing polymer and the acid anhydride is ring-opened and added to the remaining hydroxyl groups. (Preferably compounds having different isocyanate group reactivities) are added to one of the isocyanate groups to add a hydroxyl group-containing (meth) acrylate such as hydroxyethyl (meth) acrylate. Under standard conditions, a tin compound such as dibutyltin dilaurate is used as a catalyst, and the reaction is carried out at about 60 to 80 ° C.

The epoxy resin used in the synthesis of the ring-opened adduct of an epoxy (meth) acrylate and an acid anhydride is an epoxy resin such as a phenol novolak type or a cresol novolak type or a polyvinylphenol skeleton, and has a molecular weight of 1,000 or more. Preferably, more preferably, 3,000
The number is particularly preferably 4,000 or more. If the molecular weight is small, the crosslink density does not increase and the heat resistance deteriorates.

The amount of (meth) acrylic acid used in the synthesis of the ring-opening adduct of an epoxy (meth) acrylate and an acid anhydride is preferably 0.98 to 1.10 equivalents of the epoxy group, more preferably 1 to 10. 0.001 to 1.07, particularly preferably 1.01 to 1.04. If the amount of (meth) acrylic acid is small, the epoxy group remains and storage stability deteriorates. In extreme cases, gelation occurs at the time of acid anhydride conversion. Conversely, if the amount is too large, the (meth) acrylic acid remains to cause odor or to lower heat resistance.

In the ring-opening addition of an epoxy (meth) acrylate and an acid anhydride, it is effective to add 30 to 300 ppm of hydroquinone as a radical polymerization inhibitor. Although phenothiazine can be synthesized by adding about 500 ppm, its storage stability is slightly inferior to hydroquinone. When the reaction is performed while blowing air or nitrogen containing 5% oxygen into the reaction solution, the effect of inhibiting radical polymerization may increase.

In the ring-opening addition of an epoxy (meth) acrylate and an acid anhydride, a quaternary ammonium salt such as tetrabutylammonium bromide is used as a catalyst in an amount of 0.1 to 10%.
It is effective to add 5.0%, preferably 0.3 to 2.0%. If the amount of the catalyst is small, the reaction is slow. If the amount is too large, the catalyst remains in the reaction product and the insulating property is deteriorated.

The acid anhydride used in the synthesis of the ring-opening adduct of the epoxy (meth) acrylate and the acid anhydride includes succinic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, methylhexahydrophthalic anhydride and the like. It is preferable because it has good alkali solubility and can be dissolved with sodium carbonate. Phthalic anhydride, itaconic anhydride, maleic anhydride and the like are difficult to dissolve in sodium carbonate, but can be dissolved using sodium hydroxide. The acid anhydride is preferably used in the range of 0.2 to 0.95 equivalent of the epoxy group before the reaction. If it is less than 0.2 equivalent, it is difficult to dissolve in an aqueous alkali solution, and if it exceeds 0.95 equivalent, unreacted acid anhydride remains, and the physical properties of the composition such as heat resistance and electric properties are deteriorated, and both are not preferable.

The solvent used in the synthesis of the ring-opening adduct of the epoxy (meth) acrylate and the acid anhydride can sufficiently dissolve the raw materials and the reaction products.
Those having no hydroxyl group can be used. A solvent having a hydroxyl group, such as butyl cellosolve, is not preferred because it may react with an acid anhydride to give a by-product that lowers heat resistance and the like. Preferred solvents include ethers such as diglyme, esters such as ethyl carbitol acetate, ethyl cellosolve acetate and isopropyl acetate, and ketones such as methyl ethyl ketone and cyclohexanone. Aromatic hydrocarbons and the like may be used together so as not to hinder the solubility of the reaction product.

In the synthesis of the ring-opened adduct of an epoxy (meth) acrylate and an acid anhydride, the reaction temperature is preferably 60 to
It is good to carry out at 160 ° C, more preferably at 70 to 140 ° C, most preferably at 80 to 120 ° C. If the reaction temperature is too low, the reaction is slow, and if it is too high, gelation occurs or the storage stability of the reaction product deteriorates. The acid value of the reaction solution is analyzed in a timely manner. When the acid value becomes almost zero, the (meth) acrylate reaction is terminated. The reaction time varies greatly depending on the reaction temperature and the catalyst concentration, but is usually 4 to 30 hours. The acid anhydride modification reaction can be usually performed for 1 to 8 hours.

The synthesis of the ring-opened adduct of an epoxy (meth) acrylate and an acid anhydride comprises a two-step reaction as described above. In the first step, the epoxy group of the epoxy resin and the carboxyl group of (meth) acrylic acid are used. Are linked by an ester bond to form a secondary hydroxyl group at the same time. The reaction is exothermic. In the latter reaction, the secondary hydroxyl group generated earlier and the acid anhydride react with each other to form an ester bond, and at the same time, a carboxy group is generated. The reaction is slightly exothermic.

As described above, many base resins that can be dissolved in an aqueous alkali solution can be used, and they can be used in combination. However, since the base resin is excellent in heat resistance and electrical properties, the first resin composition can be used. As a base resin,
The ring-opening adduct of the polymer and the glycidyl group-containing unsaturated compound is used as the base resin of the second resin composition, as the ring-opening adduct of an epoxy (meth) acrylate and an acid anhydride or the polymer and the glycidyl group-containing unsaturated compound. Ring-opened adducts with compounds are preferred. As is well known, these can be easily cured by an active energy ray such as an electron beam and an ultraviolet ray, or a means such as heating.

The base resin preferably has a molecular weight (weight-average molecular weight in terms of styrene as determined by gel permeation chromatography) of 1,000 to 200,000, more preferably 2,000 to 100,000.
0, most preferably 5,000-80,000.
If the molecular weight is too small, heat resistance, water resistance and the like will be poor, and fluidity will be too large. If the molecular weight is too large, the alkali solubility will be poor.

The base resin has an acid value of 0.2-1.
The range is preferably 0.0 meq / g, more preferably 0.4 to 5.0 meq / g, most preferably 0.6 to 5.0 meq / g.
3.0 meq / g. If the acid value is too small, the alkali solubility will be poor, and if it is too large, the water resistance will be poor.

A preferred example of the first resin composition used in the copper-clad insulating sheet of the present invention is a ring-opened adduct of the above-mentioned polymer and a glycidyl group-containing unsaturated compound as an alkali-soluble base resin, having a molecular weight of 30,000
-80,000, acid value of 1.0-1.5 meq / g, and if necessary, an adhesive reinforcing agent (crosslinking agent), an active energy ray curing reaction initiator / sensitizer, and a curing agent Those to which an oxide or the like is added can be given.

A preferred example of the second resin composition used in the copper-clad insulating sheet of the present invention is a ring-opening addition of the above-mentioned epoxy (meth) acrylate and acid anhydride as a base resin soluble in an aqueous alkali solution. Ring-opening adduct of a product or polymer with a glycidyl group-containing unsaturated compound,
Molecular weight 3,000-50,000, acid value 0.6-3.
0 meq / g, and if necessary, an adhesive reinforcing agent (crosslinking agent), an active energy ray curing reaction initiator,
As the sensitizer and the curing agent, those prepared with peroxide and the like can be mentioned.

The second resin composition has a higher alkali solubility than the first resin composition by changing the base resin, the molecular weight thereof, the acid value, and the amount of the adhesive reinforcing agent (crosslinking agent) added. It is prepared to be large, preferably twice or more. Adding a crosslinking agent having a high fluidity before curing improves the alkali permeability of the obtained resin composition, so that the fluidity during heating and the alkali solubility can be increased at the same time.

According to the present invention, the second resin composition has a higher solubility in an aqueous alkali solution than the first resin composition.
The second resin composition may be soluble in an aqueous alkaline solution at a lower temperature than the first resin composition. Generally molecular weight 3
0000-80,000, acid value 1.0-1.5 meq
The inventors of the present invention have found that the solubility of alkali resin becomes extremely poor when the temperature of the resin becomes lower than a certain temperature (hereinafter, referred to as "point A").

Therefore, a resin having a relatively high point A is used as the base resin of the first resin composition, and the base resin of the second resin composition is used even at a lower temperature than the base resin of the first resin composition. When a copper-clad insulating sheet made of a resin having alkali solubility or a resin whose solubility is hardly affected by a change in temperature is used, the layer of the first resin composition is alkali-dissolved at a point A or more of the base resin. After forming the blind via hole, there is a method in which the layer of the second resin composition is alkali-dissolved at a temperature lower than the point A. As a result, the second flowing into the access via-shaped through via hole
The layer of the resin composition can be completely dissolved without increasing the undercut between the conductors of the blind via hole even after the layer of the first resin composition is dissolved.

For example, if the point A of the base resin of the first resin composition is 30 ° C., the layer of the first resin composition is
After dissolving with a 0.2 to 2% by weight sodium carbonate solution at １００100 ° C. to form blind via holes, the layer of the second resin composition is removed at 0 to 30 ° C. by 1 to 5% by weight sodium carbonate. Dissolve in solution or 0.5-10% by weight sodium hydroxide solution.

In the above, when dissolving the layer of the second resin composition flowing into the through via hole, if sodium hydroxide is used, the copper foil via is dissolved simultaneously with the dissolution of the resin composition in the layer. It is more preferable because the etching resist for forming holes can be removed.

The above-mentioned ring-opened adduct of an epoxy (meth) acrylate and an acid anhydride, unlike other resins, has almost no difference in solubility depending on the temperature, and is therefore suitable as a base resin for the second resin composition. It is.

A photoreactive compound and / or a thermosetting resin can be added to the resin composition used in the present invention as an adhesive reinforcing agent or a crosslinking agent, and the amount thereof is based on 100 parts by weight of the solid content of the base resin. From 40 to 250 parts by weight. As the photoreactive compound, polyether type, polyester type, unsaturated polyester type, urethane type, epoxy type, polyester / urethane type, polyacetal type, polybutadiene type and the like can be used. For example, 2-
Ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2
Urethane acrylate as a functional oligomer, 1,3
-Butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, polyethylene glycol 400 diacrylate, hydroxypivalate neopentyl glycol diacrylate, Examples include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, triallyl isocyanurate and the like, or adducts or condensates thereof. As thermosetting resin, acrylic resin, urethane resin, epoxy resin, polyester resin, polyether resin, alkyd resin, polyvinyl chloride resin, fluorine resin, silicon resin,
Examples include vinyl acetate resin and polyvinyl alcohol.

Urethane acrylate is preferred as the above-mentioned adhesive reinforcing agent. Urethane acrylate particularly has an effect of enhancing the adhesion between the surface copper foil and the resin layer, and the acrylate is preferably a non-yellowing / medium hard type, and Aronix M manufactured by Toagosei Chemical Industry Co., Ltd. -1
100, Aronix M-1600, Aronix M-
1700 and the like. It is preferable that one or more urethane acrylates are added in an amount of 40 to 120 parts by weight based on 100 parts by weight of the solid content of the base resin. If it exceeds 120 parts by weight, the solubility in the aqueous alkali solution becomes poor, and resin residues are likely to be generated. When a conductive material is formed to conduct the inner layer conductor pattern to the outer layer copper foil, sufficient conduction cannot be obtained if there is a resin residue. 4
If the amount is less than 0 parts by weight, sufficient adhesion strength between the resin composition and the copper of the outer layer cannot be obtained.

Benzoin, benzoin, benzoin alkyl ether, 1- as a benzoin ether-based reaction initiator for active energy ray curing such as ultraviolet rays and electron beams.
Hydroxycyclohexyl phenyl ketone; benzyl dialkyl ketal as ketal; 2,2′-diallylacetophenone, 2-hydroxyacetophenone, pt-butyltrichloroacetophenone, pt-butyldichloroacetophenone as acetophenone; benzophenone as benzophenone; -Chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,
4'-bisdimethylaminobenzophenone, methyl o-benzoylbenzoate, 3,3'-dimethyl-4-methoxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, dibenzosuberone, bendimethylketal; thioxanthone as a thioxanthone system , 2-
Chlorothioxanthone, 2-alkylthioxanthone,
2,4-dialkylthioxanthone, 2-alkylanthraquinone, 2,2′-dichloro-4-phenoxyacetone and the like can be used. The amount is 1 base polymer solids.
0.5 to 10 parts by weight per 100 parts by weight is preferred.
If the amount is less than 0.5 part by weight, the reaction does not sufficiently start, and if the amount exceeds 10 parts by weight, the resin layer becomes brittle. When using by electron beam irradiation, the reaction initiator may be omitted.

As a sensitizer at the time of the reaction of curing with an active energy ray such as an ultraviolet ray and an electron beam, Nissocure EPA, EMA, IAMA, EHMA, MABP, manufactured by Shin Nisso Chemicals, Inc.
EABP etc., Kayacure EPA manufactured by Nippon Kayaku Co., Ltd.,
DETX, DMBI, etc., Ward Blenkins
Opt's Quantacure EPD, BEA, EO
B, DMB, etc., DABA manufactured by Osaka Organic Co., Ltd., PAA, DAA manufactured by Daito Chemical Co., Ltd., and the like. The addition amount is 0.5 to 1 based on 100 parts by weight of the solid content of the base polymer.
0 parts by weight is preferred. When the amount is less than 0.5 part by weight, the reaction rate of the active energy ray curing does not improve. When the amount exceeds 10 parts by weight, the reaction speeds up and the shelf life is reduced. When electron beam irradiation is used, the reaction sensitizer may be omitted.

As the curing agent, peroxides can be used. Among them, alkyl peroxides such as dibutyl peroxide, butyl cumyl peroxide, and dicumyl peroxide, and aryl peroxides are preferable from the viewpoint of storage stability. The amount is preferably 1 to 10 parts by weight based on 100 parts by weight of the solid content of the base polymer.
If the amount is less than 1 part by weight, the curing time is prolonged, and if it exceeds 10 parts by weight, the shelf life is shortened and workability is deteriorated. When performing ultraviolet irradiation, electron beam irradiation, or the like, a curing agent is not necessarily required, but it is preferable to add a curing agent in order to enhance adhesion such as copper foil adhesion stability and solder heat resistance.

In the method for producing a multilayer wiring board having via holes using a copper-clad insulating sheet according to the present invention, the thickness between the conductor pattern surface of the inner layer panel and the copper foil is 20 to 7 mm.
0 μm is preferred. If it is less than 20 μm, insulation resistance and withstand voltage between layers cannot be ensured. If it exceeds 70 μm, undercut becomes large due to alkali dissolution when forming via holes in small diameter holes, and sufficient connection reliability by plating of via holes or conductive pastes Can not be obtained.

In the copper-clad insulating sheet of the present invention, the thickness of the layer of the first resin composition applied to the copper foil is 30 to 60 μm.
m, the layer of the second resin composition is preferably 20 to 40 μm.

The copper-clad insulating sheet of the present invention can be manufactured by applying a first resin composition to a copper foil and then applying a second resin composition thereon. The copper-clad insulating sheet is laminated on one or both sides of the inner layer insulating panel on which a conductive pattern has been formed in advance by a hot roll, and an etching resist is formed on the copper foil and selectively etched to form an inner layer insulating panel. After forming fine holes corresponding to the specific conductor pattern, removing the resin layer under the fine holes etched away with an alkaline aqueous solution and curing the resin layer, the conductive material on the inner layer panel By electrically connecting the pattern to the outer layer copper foil and then selectively etching the outermost layer copper foil to form a predetermined pattern, a multilayer printed wiring board having blind via holes can be manufactured.

The flowability of the resin composition during heating can be controlled mainly by adjusting the molecular weight of the base resin. As described above, the preferred molecular weight of the base resin used in the present invention is 1,000 to 200,000.
However, if it exceeds 30,000, the fluidity of the resin at the time of heating is almost negligible, and if it is 10,000 to 30,000, the fluidity is slightly generated, and if it is less than 10,000, the resin has fluidity. However, as described above, when a large amount of a flowable cross-linking agent is added to the resin composition before curing, even if the molecular weight of the base polymer is large, it is possible to increase the flowability of the resin composition during heating. .

In the copper-clad insulating sheet of the present invention, the first resin composition has a small resin flow at the time of heating, but the second resin composition has a large resin flow at the time of heating in the laminating step. The resin can penetrate between the conductive patterns of the inner layer panel having the above and between the conductive patterns and the surface of the insulating panel to fill the gap. At this time, if there is a through hole in the inner layer plate, the second resin composition also flows into the through hole. Since the resin flow of the first resin composition layer during heating in the laminating step is small, the thickness of the insulating layer between the conductor pattern surface and the copper foil can be ensured.

In the method for producing a multilayer printed wiring board having blind via holes and through via holes using the copper-clad insulating sheet of the present invention, the curing of the resin layer is performed by irradiation with an electron beam or ultraviolet rays and / or heating. In the case of heating, the temperature is preferably in the range of 80 to 180 ° C, more preferably 150 to 170 ° C.
If the temperature exceeds 180 ° C. due to heat curing, the insulating resin constituting the inner layer panel deteriorates. If the temperature is less than 80 ° C., it takes a long time to cure, and the crosslinking may be insufficient and the insulation resistance may not be sufficient.

When the diameter of the via hole becomes small, the resin flows out at the time of heating, and the portion where the flow is large causes the resin to cover the surface of the copper foil for connection of the lower inner layer panel. A defect that cannot be obtained occurs.
For this reason, ultraviolet irradiation or electron beam irradiation is performed while the resin starts to flow by heating, and active energy rays are applied to the resin below the via hole opened in the copper foil or the portion facing the via hole to cure the resin. A resin flow weir is formed, and it is possible to prevent the resin from flowing more than necessary. 1 for electron beam irradiation
Good conditions of 80 to 300 kV and 10 to 30 Mrad,
Not only the curing of the resin layer around the via hole but also the resin layer under the copper foil of 18 to 35 μm can be cured by transmitting the copper foil with the electron beam.

In the method for manufacturing a multilayer printed wiring board having blind via holes and through via holes using the copper-clad insulating sheet of the present invention, when laminating the copper-clad insulating sheet on the inner layer panel, the resin layer and the inner layer It is preferable that the surface of the copper wiring pattern for the inner layer is subjected to a roughening treatment, a black oxide treatment, a brown oxide treatment, a red oxide treatment or the like in order to secure an adhesive force with the copper wiring pattern.

In the method of manufacturing a multilayer printed wiring board having a blind via hole and a through via hole using the copper-clad insulating sheet of the present invention, the first and second copper foils formed on the surface below the via hole formed in the copper foil. The layer of the resin composition of No. 2 can be dissolved in an organic solvent, but the use of an alkaline aqueous solution is more suitable in view of the reliability and workability of the via hole. Because when the resin composition is dissolved in an organic solvent, it is a swelling and dissolution reaction,
There is a problem that the boundary of the resin after melting is not smooth but rough, and the organic solvent remains near the boundary. Therefore, when plating the via hole in which the resin is dissolved, the effect of the residual organic solvent and the boundary of the resin make it difficult for electroless plating to precipitate, generating a pinhole in the plating, and remaining in the plated via hole. This is because the organic solvent evaporates and causes problems such as voids, bubbles, and blisters, which make electrical and mechanical connections by via holes between conductive circuits between layers unstable, so that connection reliability cannot be obtained.
On the other hand, when dissolving the resin with an aqueous alkali solution, the dissolution rate is high because the alkali-soluble groups such as carboxyl groups and phenolic hydroxyl groups react and dissolve, and the resin is sequentially dissolved from the portion in contact with the aqueous alkali solution, so the resin is The boundary of becomes clear.

Further, it is further preferable that a multilayer printed wiring board having via holes can be easily manufactured in a conventional printed wiring board manufacturing process without deteriorating the working environment unlike an organic solvent. In other words, if an alkali-soluble etching resist is used to form via holes for copper foil, the resin layer below the copper foil via holes will dissolve simultaneously with the resist during the film stripping process after copper foil etching. it can. When the alkali-developing dry film is used as a resist, the first and second resin composition layers below the copper foil via holes are dissolved and removed simultaneously with the removal of the resist using an aqueous sodium hydroxide solution for stripping. Is possible and more preferred.

After dissolving a resin layer having an alkali-soluble group having a carboxyl group or a phenolic hydroxyl group with an aqueous alkali solution and washing with an acid, no alkali component remains, and the subsequent electroless plating is carried out. Good precipitation,
Since no defects such as voids, bubbles and blisters are generated, a highly reliable via hole can be formed. When the copper wiring pattern of the inner layer panel is blackened, etc., when the via hole is neutralized with acid, the resin is dissolved on the blackened surface of the inner layer panel in the via hole. The copper oxide film of the chemical treatment dissolves, and the color of copper comes out. If the resin remains on the surface of the blackened coating film, the color of the copper is not visible, so whether the alkali is dissolved or not can be determined by this neutralization treatment.

In the production of a multilayer printed wiring board having blind via holes and through via holes using the copper-clad insulating sheet of the present invention, fine holes are formed by etching copper foil, and the fine holes are resin-coated with an alkaline aqueous solution. As a method of electrically connecting the conductor pattern of the inner insulating panel exposed by dissolving the layer and the copper foil of the outer layer, electroless plating and / or electrolytic plating, gold, silver, copper,
A method in which a conductive paste such as solder is applied by screen printing, dispenser, pin printing, and the like and dried and cured can be used.

The copper-clad insulating sheet of the present invention is formed by forming a layer of a first resin composition and a layer of a second resin composition so that a multilayer printed wiring board can be manufactured continuously. It can be wound into a roll via a release film or release paper, and the rolled copper-clad insulating sheet can be continuously laminated to the inner layer panel by a hot roll.

The copper-clad insulating sheet of the present invention has a first and a second resin composition layer formed on a mat surface of a copper foil,
A photosensitive resin may be applied in advance on the copper foil on the opposite side of the copper foil. After laminating the copper-clad insulating sheet to the inner layer panel, instead of forming a dry film or etching resist, if it is provided in advance on a copper foil, it can be omitted in the manufacturing process of the multilayer printed wiring board in the process of forming the dry film or etching resist. If the economy and the number of processes are reduced, the yield is improved, and the quality can be superior.

[0067]

When the copper-clad insulating sheet of the present invention is used, in the step of dissolving the layer of the first resin composition exposed by etching with alkali, under the condition of dissolving the blind via hole with alkali, the access via-shaped through via hole is formed. The second resin composition that has flowed in is dissolved in a short time after the layer of the first resin composition is dissolved, and the undercut of the resin layer between the conductor pattern of the inner layer plate and the outer layer conductor is performed. Can be pressed as much as possible. Thus, when the copper-clad insulating sheet of the present invention is used, the above-described blind hole and the access-hole-shaped through via hole can be simultaneously and satisfactorily formed. In addition, since a thin copper-clad insulating sheet is used instead of the conventional prepreg in which resin is impregnated with thick glass fiber, CAF does not occur in the insulating layer, reliability is obtained, and thin multilayer printed circuit boards can be manufactured. It is.

[0068]

EXAMPLES Synthesis of Base Resin Synthesis Example 1 40 parts by weight of n-butyl methacrylate, 15 parts by weight of methyl methacrylate, 10 parts by weight of styrene, 10 parts by weight of hydroxyethyl methacrylate, 25 parts by weight of methacrylic acid, and azobisisobutylnitrile 1 The mixture consisting of parts by weight was dropped into 120 parts by weight of propylene glycol monomethyl ether kept at a temperature of 80 ° C. in a nitrogen gas atmosphere over 5 hours. After aging for 1 hour, 0.5 part by weight of azobisisobutylnitrile was further added and the mixture was aged for 2 hours to synthesize a methacrylic resin having a carboxyl group. Next, while blowing in air, 20 parts by weight of glycidyl methacrylate, 1.5 parts by weight of tetrabutylammonium bromide and 0.15 parts by weight of hydroquinone as a polymerization inhibitor were added, and reacted at a temperature of 80 ° C. for 8 hours to give a molecular weight of 50,50. 000-70,000, acid value 1.2m
A base resin having a carboxyl group of eq / g and an unsaturated equivalent of 1.14 mol / kg was synthesized.

Synthesis Example 2 Cresol novolak type epoxy resin (Epototo YDCN704 manufactured by Toto Kasei Co., Ltd.) was placed in a 3 liter flask.
983 g and 742 g of ethyl carbitol acetate were added and dissolved by heating to 110 ° C., 1.12 g of phenothiazine as a radical polymerization inhibitor and 11.21 g of tetrabutylammonium bromide as a catalyst were added, and the temperature was maintained at 110 ± 5 ° C. Then, 337 g of acrylic acid was gradually dropped over 3 hours. 120 ± 5 ℃ after 3 hours
The reaction was continued for about 8 hours until the acid value was reduced from 2.23 to almost 0 while measuring the acid value by neutralization titration. Next, 138 g of succinic anhydride was added, and the mixture was kept at 110 ± 5 ° C. and reacted for 3 hours from the time when the succinic anhydride was dissolved to prepare an epoxy acrylate having a carboxyl group and a molecular weight of 8,000 to 10,000. .

Example 1 (Preparation of First Resin Composition) 65 parts by weight of the resin of Synthesis Example 1 and trimethylolpropane triacrylate as a crosslinking agent (Aronix M-30 manufactured by Toagosei Chemical Industry Co., Ltd.)
The first resin composition was prepared by sufficiently mixing 35 parts by weight of 8) and 1.5 parts by weight of Parkmill D manufactured by NOF Corporation as a curing agent. In a copper-clad insulating sheet formed of the resin composition with a resin thickness of 70 μm, the alkali dissolution time of the composition was 120 ° C. at 40 ° C. using a 1% sodium carbonate solution.
Seconds.

(Preparation of Second Resin Composition) 30 parts by weight of the resin of Synthesis Example 1, 70 parts by weight of Aronix M-308 manufactured by Toagosei Chemical Industry Co., Ltd. as a crosslinking agent, and Nippon Oil & Fats Co., Ltd. as a curing agent A second resin composition was prepared by thoroughly mixing 1.5 parts by weight of Park Mill D manufactured by Toshiba Corporation. 30 parts of the resin composition
The alkali dissolution time of a copper-clad insulating sheet formed with a resin thickness of μm was 20 seconds at 40 ° C. using a 1% sodium carbonate solution, and 50 seconds with a resin thickness of 70 μm.

(Preparation of Copper-Clad Insulating Sheet) The matting surface of a mat-treated 35 μm-thick copper foil is coated with the above first resin composition using a comma coater and dried at 60 ° C. for 20 minutes to form a 70 μm-thick resin layer. Was formed.

The second resin composition was similarly coated and dried on the first resin composition layer to form a 30 μm thick resin layer, and a copper-clad insulating sheet as shown in FIG. 1 was prepared. .

(Preparation of Multilayer Printed Wiring Board) A multilayer printed wiring board having via holes was prepared using the copper-clad insulating sheet of the present invention. This manufacturing method will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a copper-clad insulating sheet of the present invention, and FIGS. 2 to 10 are schematic cross-sectional views for explaining a manufacturing process and a configuration of a multilayer printed wiring board using the copper-clad insulating sheet of the present invention. It is. 35μ as inner layer panel
0.5mmφ through-hole 10 by drilling a 0.6mm glass epoxy double-sided copper clad board with a thickness of 0.6mm
Is provided, an inner layer panel 7 having a copper wiring pattern 6 formed at a predetermined position by selective etching is prepared, and the surface of the copper wiring pattern 6 of the inner layer panel 7 is treated with sodium chlorite 37 g / liter, The solution was treated with a solution consisting of 10 g / l of sodium and 20 g / l of trisodium phosphate dodecahydrate for 5 minutes at 95 ° C, washed well with water, dried and blackened.

Next, the copper-clad insulating sheet 1 is laid on both sides of the inner-layer panel 7 (FIG. 2), and laminated by a metal roll at 75 ° C. to obtain a copper-clad laminate panel incorporating the inner-layer panel. Created. Here, the second resin composition layer 3 has a large fluidity, so that it flows between the copper wiring patterns 6 and into the through holes 10, and the first resin composition layer 2 has little resin flow, so that the lower copper wiring pattern The copper clad laminate panel shown in FIG.

Portions of the copper clad laminate panel panel except for the locations where the 0.3-0.5 mmφ copper foil via holes 8 and the 0.8 mmφ access hole via holes 17 are formed on the surface of the copper foil 4. Then, an alkali-soluble etching resist was formed by a screen printing method, and copper at the via hole of the copper foil was etched with a cupric chloride solution. Followed by 1 wt% sodium carbonate solution 40 ° C. at a spray pressure of 1.5 kg / cm ^2, at the same time dissolve and remove the layer 2 of the first resin composition of the underlying portion of the via hole 8 of the copper foil Then, the lower copper wiring pattern 6 is exposed to form a blind via hole as shown in FIG. 6, and at the same time, the second resin composition flowing into the through hole 10 is completely dissolved to form a via hole for an access hole. 17 was formed.

Subsequently, after washing with water and a 10% sulfuric acid aqueous solution, the portion of the blind via hole where the resin was exposed was irradiated with an electron beam to cure the surface of the resin. First
After curing the layer 2 of the resin composition and the layer of the second resin composition, the silver paste 14 is simultaneously printed on the blind via holes and the through holes as shown in FIG. 7, and then at 150 ° C. for 45 minutes. After baking, an etching resist 15 is formed as shown in FIGS. 8 and 9, etching and stripping are performed, and a solder resist 16 which is an overcoat of silver paste is formed as shown in FIG. A multilayer printed wiring board having blind via holes to be connected and access-hole-shaped through via holes to connect four layers of conductor patterns was obtained.

The peel strength between the copper foil and the resin layer of the printed wiring board prepared as described above is 1.4 kg / cm.
was gotten. Solder heat resistance is 280 in 25mm square pattern
There was no abnormality at 3 ° C for 3 minutes. Surface insulation resistance is initially 10 ¹⁴
Ω, and 10 ¹² Ω after moisture resistance (C-96 / 40/95). The interlayer insulation resistance is initially 10 ¹² Ω, after moisture resistance (C-96 /
40/95) 10 ¹¹ Ω was obtained. Breakdown withstand voltage is initial,
After moisture resistance (C-96 / 40/95), the voltage was DC 3000 V or more. Interlayer dielectric strength is measured by pressure cooker test (1
No abnormality at 30 ° C., 85% RH, 100 hours, DC 20 V bias). The conduction resistance of the blind via hole is as follows: temperature cycle 125 ° C. for 30 minutes, −65 ° C.3
As a result of a 100-cycle test with 0 minute as one cycle, there was almost no change.

Example 2 (Preparation of Resin Composition of First Layer) 65 parts by weight of the resin of Synthesis Example 1 and trimethylolpropane triacrylate as a crosslinking agent (Aronix M-30 manufactured by Toagosei Chemical Industry Co., Ltd.)
The first resin composition was prepared by sufficiently mixing 35 parts by weight of 8) and 1.5 parts by weight of Parkmill D manufactured by NOF Corporation as a curing agent. The alkali dissolution time of a copper-clad insulating sheet having the composition formed with a resin thickness of 70 μm is 120 seconds at 40 ° C. using a 1% sodium carbonate solution, and 7 to 8 at 20 ° C.
Minutes.

(Preparation of Resin Composition for Second Layer) To 65 parts by weight of the epoxy acrylate having a carboxyl group prepared in Synthesis Example 2, urethane acrylate (Aronix M- manufactured by Toagosei Chemical Industry Co., Ltd.) was used as an adhesive reinforcing agent. 170
0) 35 parts by weight were added, and as a curing agent, 1.5 parts by weight of Park Mill D manufactured by NOF Corporation was dissolved in xylene and then mixed to prepare a second resin composition. The alkali dissolution time of a copper-clad insulating sheet having the composition formed with a resin thickness of 30 μm was determined using a 1% sodium carbonate solution.
It was 60 seconds at 0 ° C.

(Preparation of Copper-Clad Insulating Sheet) The matte surface of a matte-treated 35 μm-thick copper foil is coated with the above-mentioned first resin composition using a comma coater, and dried at 60 ° C. for 20 minutes to form a 70 μm-thick resin layer. Was formed.

On the layer of the first resin composition, a layer of the second resin composition was similarly coated and dried to form a 30 μm-thick resin layer. Created.

(Preparation of Multilayer Printed Wiring Board) A board pressure of 1.0 mm having a 35 μm-thick copper foil as an inner layer panel is 0.5 mm by drilling on a double-sided glass epoxy copper clad board.
After the through-hole 10 of φ is provided, an inner layer panel 7 having a copper wiring pattern 6 formed at a predetermined position by selective etching is prepared, and the surface of the copper wiring pattern 6 of the inner layer panel 7 is treated with sodium chlorite 37 g / Liter, sodium hydroxide 10g / liter, trisodium phosphate dodecahydrate 2
Treated at 95 ° C. for 5 minutes with a solution consisting of 0 g / liter,
After being well washed with water, it was dried and blackened.

Next, the copper-clad insulating sheets 1 are laid on both sides of the inner-layer panel 7 (FIG. 2) and laminated at 75 ° C. with a metal roll to produce a copper-clad laminate panel incorporating the inner-layer panel. did. Here, the layer 3 of the second resin composition has a large fluidity, so that the layers 3 between the copper wiring patterns 6 and the through holes 1
0, the layer 2 of the first resin composition has almost no resin flow, so that the copper clad laminate panel shown in FIG.

Portions of the surface of the copper foil 4 of the copper clad laminate panel except for the via holes 8 of the copper foil of 0.3 to 0.5 mmφ and the via holes 17 for the access holes of 0.8 mmφ. Then, an alkali-soluble etching resist was formed by a photo method, and the copper at the via hole of the copper foil was etched with a cupric chloride solution. Then 4
1.5 kg / c of a 1% by weight sodium carbonate solution at 0 ° C.
At a spray pressure of m ² , the lower layer of the first resin composition 2 at the location of the via hole 8 of the copper foil is simultaneously dissolved and removed to expose the lower copper wiring pattern 6 as shown in FIG. At the same time as forming the blind via holes, the second resin composition flowing into the through holes 10 was completely dissolved to form the access hole via holes 17.

Subsequently, after washing with water and a 10% sulfuric acid aqueous solution, the portion of the blind via hole where the resin was exposed was irradiated with an electron beam to cure the surface of the resin. First
After curing the layer 2 of the resin composition and the layer of the second resin composition, the silver paste 14 is simultaneously printed on the blind via holes and the through holes as shown in FIG. 7, and then at 150 ° C. for 45 minutes. After baking, an etching resist 15 is formed as shown in FIGS. 8 and 9, etching and stripping are performed, and a solder resist 16 which is an overcoat of silver paste is formed as shown in FIG. A multilayer printed wiring board having blind via holes to be connected and access-hole-shaped through via holes to connect four layers of conductor patterns was obtained.

The peel strength between the copper foil and the resin layer of the printed wiring board prepared as described above is 1.4 kg / cm.
was gotten. Solder heat resistance is 280 in 25mm square pattern
There was no abnormality at 3 ° C for 3 minutes. Surface insulation resistance is initially 10 ¹⁴
Ω, and 10 ¹² Ω after moisture resistance (C-96 / 40/95). The interlayer insulation resistance is initially 10 ¹² Ω, after moisture resistance (C-96 /
40/95) 10 ¹¹ Ω was obtained. Breakdown withstand voltage is initial,
After moisture resistance (C-96 / 40/95), the voltage was DC 3000 V or more. Interlayer dielectric strength is measured by pressure cooker test (1
No abnormality at 30 ° C., 85% RH, 100 hours, DC 20 V bias). The conduction resistance of the blind via hole is as follows: temperature cycle 125 ° C. for 30 minutes, −65 ° C.3
As a result of a 100-cycle test with 0 minute as one cycle, there was almost no change.

[0088]

According to the copper-clad insulating sheet of the present invention, a multilayer printed wiring board having a blind via hole and an access hole-like through via hole having excellent physical properties, electrical properties and reliability can be obtained. In addition, since blind via holes and through via holes can be easily and collectively formed by etching copper foil and dissolving the resin with an alkaline aqueous solution, productivity is higher than conventional drilling, in which holes are drilled one by one. Is greatly improved. Also, regardless of the variation in the depth of the inner layer copper foil pattern, the blind hole can be reliably provided by dissolving the resin layer up to the inner layer copper foil pattern. There is no hole connection failure, and there is no short-circuit failure erroneously connected to the copper foil pattern of another layer for the inner layer.

Further, for insulation between the inner layer panel and the outer copper foil, a thin copper-clad insulating sheet is used instead of a conventional prepreg in which a thick glass fiber is impregnated with a resin.
Since no CAF is generated in the insulating layer and the thickness of the printed wiring board can be reduced, a highly reliable high-density multilayer printed wiring board can be obtained. Therefore, it is very useful because it enables the manufacture of a multilayer printed wiring board requiring blind via holes and through via holes used for high-density mounting in various electronic devices.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration of a copper-clad insulating sheet of the present invention.

FIG. 2 is a diagram showing a structure before a thermocompression bonding of an inner layer panel having a copper wiring pattern on its surface and a copper-clad insulating sheet in a process of manufacturing a multilayer printed wiring board having via holes using the copper-clad insulating sheet of the present invention. FIG.

FIG. 3 is a schematic cross-sectional view showing the configuration of an inner layer panel after lamination in the same manufacturing process.

FIG. 4 is a schematic cross-sectional view showing the inner layer panel after a copper foil on the surface and an etching resist are formed in the same manufacturing process.

FIG. 5 is a schematic cross-sectional view showing the inner layer panel after forming blind via holes by etching copper on the surface in the same manufacturing process.

FIG. 6 is a schematic cross-sectional view of the inner layer panel after dissolving a resin layer below a copper foil blind via hole and dissolving a resin in a through hole to form an access hole-like through via hole in the same manufacturing process. FIG.

FIG. 7 is a schematic cross-sectional view after a conductive paste is formed in the same manufacturing process.

FIG. 8 is a schematic cross-sectional view after forming an etching resist for etching an outer copper foil pattern in the same manufacturing process.

FIG. 9 is a schematic cross-sectional view after unnecessary copper foil of an outer layer is etched and an etching resist is removed in the same manufacturing process.

FIG. 10 is a schematic cross-sectional view after a solder resist is formed in the same manufacturing process.

FIG. 11 is a schematic cross-sectional view showing a configuration of a conventional multilayer printed wiring board having blind via holes in a manufacturing process before an inner layer panel having a copper wiring pattern on its surface and a copper foil are heat-pressed via a prepreg; FIG.

FIG. 12 is a schematic cross-sectional view showing the configuration of the copper-clad laminate panel after the thermocompression bonding in the manufacturing process.

FIG. 13 is a schematic sectional view showing the copper clad laminate panel after forming blind via hole holes by drilling in the same manufacturing process.

FIG. 14 is a schematic cross-sectional view showing the copper-clad laminate panel after forming through holes by drilling in the same manufacturing process.

FIG. 15 is a schematic cross-sectional view after a plating process in the same manufacturing process.

FIG. 16 is a schematic sectional view after an etching resist is formed in the same manufacturing process.

FIG. 17 is a schematic sectional view after unnecessary copper foil is removed by etching in the same manufacturing process.

FIG. 18 is a schematic sectional view in the same manufacturing process after removing an etching resist.

FIG. 19 is a schematic cross-sectional view after a solder resist is formed in the same manufacturing process.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 copper foil 2 layer of first resin composition 3 layer of second resin composition 4 copper-clad insulating sheet 5 prepreg 6 copper wiring pattern 7 inner layer panel 8 copper foil via hole 9 blind via hole 10 penetration Hole (through via hole) 11 Plating through hole 12 Etching resist 13 Hole for via hole 14 Conductive paste 15 Etching resist 16 Solder resist 17 Access hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomio Kambayashi 1 Nagoya Research Center, Funai-cho, Minato-ku, Nagoya City, Aichi Prefecture (72) Inventor Jin Kato Minato-ku, Nagoya City, Aichi Prefecture Nagoya Research Institute, 1-Agosei Chemical Industry Co., Ltd. (72) Inventor Takehisa Hattori Examiner, Kina, Nagoya Research Institute, 1-Agosei Chemical Industry Co., Ltd. Minoru

Claims (1)

(57) [Claims] 1. A layer of a first resin composition which is soluble in an aqueous alkali solution and has low fluidity upon heating is formed on a roughened surface of a copper foil, and the layer having a solubility in an aqueous alkaline solution is formed on the layer. A second resin having a larger fluidity when heated than the first resin composition
A copper-clad insulating sheet for a printed wiring board formed by forming a layer of the resin composition described above.