JPH06260733A - Copper-clad insulating sheet resin composition - Google Patents

Abstract

PURPOSE:To obtain a copper-clad insulating sheet high in resistance to both mechanical and thermal shock and free from cracking by a method wherein the insulating sheet is made of material primarily composed of acrylic resin, methacrylic resin, and crosslinking agent all specified in a mixing weight ratio. CONSTITUTION:A layer 2 of first resin composition soluble in alkaline water solution and small in fluidity at a high temperature is formed on the roughened surface of a copper foil 4, and a layer 3 of second resin composition soluble in alkaline water solution and large in fluidity at a high temperature is formed on the layer 2 for the formation of a copper-clad insulating sheet 1 used for a printed wiring board, wherein resin composition is primarily composed of (meth) acrylic resin and cross-linking agent, and first resin composition and second resin composition are so set in composition as to satisfy a formula, weight ratio of (meth) acrylic resin to crosslinking agent in first resin composition = (0.9 to 1.1)X weight ratio of (meth) acrylic resin to cross-linking agent in second resin composition. By this setup, a multilayer printed wiring board excellent in physical and electrical properties and reliability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a copper clad insulating sheet for producing a multilayer printed wiring board suitable for high density mounting. In particular, the present invention provides a resin composition for a copper-clad insulating sheet, which can be manufactured with excellent mass productivity of a multilayer printed wiring board having a blind via hole having excellent physical properties and electrical properties.

[0002]

2. Description of the Related Art As electronic equipment becomes smaller and more multifunctional,
At present, printed wiring boards are moving toward higher density. For example, finer conductor circuits, higher multilayers, through via holes, blind via holes, through via holes and interstitial via holes such as barrier via holes, and small chips. There are high-density mounting by surface mounting of parts.

In order to explain a conventional method for manufacturing a multilayer wiring board having a blind via hole, schematic cross sections of respective steps are shown in FIGS. 10 to 17. As shown in FIG. 10, an inner layer panel 7 having a copper wiring pattern 6 previously formed by an etching method is prepared, and one or two prepregs 5 are stacked between the outer layer copper foil 4 and the inner layer panel 7. By laying up and heat-pressing at a temperature of 160 to 180 ° C. for 60 to 120 minutes at a pressing pressure of 15 to 50 kg / cm ² ,
A copper clad laminate panel having the inner layer wiring pattern shown in 1 is obtained. A vacuum hot press may be used when accuracy is required.

Next, holes are sequentially drilled at predetermined positions by a drill machine to form blind via hole holes 13 as shown in FIG. Subsequently, when the conventional through hole 10 is provided, it becomes as shown in FIG.

When conventional electroless copper plating and electrolytic copper plating are carried out to form the plated through holes 11, as shown in FIG.
After the etching resist 12 is formed (FIG. 15) and the subsequent etching is performed, the result is as shown in FIG. 16. Finally, the etching resist film is stripped, and as shown in FIG. 17, the blind via hole is formed. A multilayer printed wiring board having is obtained.

In order to form a blind via hole with a drill as described above, it is not possible to open a panel by laminating a plurality of panels like an ordinary through hole.
Since a drill with a small diameter of about 5 mm has a large runout, it is necessary to open each hole one by one, and it takes a very long time for drilling, and there is a drawback that the production efficiency is poor. In addition, in order to control the depth of the drill tip during drilling,
It is necessary to match the movement distance in the drilling direction, generally the Z-axis direction, with the depth of the copper wiring pattern on the inner layer panel surface. However, as mentioned above, small-diameter drills have large run-out, and there are variations in the position of the copper wiring pattern in the Z-axis direction, so it is difficult to control accurately, and if the drilling is shallow, it will not reach the lower copper wiring pattern, If the drilling process is too deep, the copper wiring pattern will come into contact with the underlying copper wiring pattern, resulting in a short circuit defect.

Further, in the conventional method for manufacturing a multilayer printed circuit board, a hot press, a vacuum hot press or the like is generally used as described above, and therefore an inner layer board panel, a prepreg and a copper foil are prepared in preparation for the hot press. It is necessary to lay up a release film, a mirror press plate, etc., thermocompress them with a heat press or a vacuum heat press, and then take them out and dismantle them. This production is a batch operation and requires a large number of man-hours such as lay-up, temperature rise during heating, thermocompression bonding, cooling and disassembly. Productivity increases with automation, but
The apparatus for this purpose is expensive, and there is a problem that a large-sized heat press apparatus capable of thermocompression bonding in large quantities is required.

The present inventor has already eliminated the above-mentioned drawbacks of the conventional method, and is capable of producing a multilayer printed wiring board having a blind via hole with excellent physical properties and electrical properties and stable quality with excellent mass productivity. The present invention provides a tension insulating sheet and a resin composition used therefor (Japanese Patent Application No. 4-
237733 and Japanese Patent Application No. 4-88395). According to the present invention, a layer of a first resin composition having a low fluidity when heated is formed on a roughened surface of a copper foil, and a layer of a second resin composition having a high fluidity when heated is further formed thereon. The present invention relates to a copper-clad insulating sheet for a printed wiring board having a resin composition, a resin composition used for the same, and a method for producing a multilayer printed circuit board using the copper-clad insulating sheet, wherein the resin composition is a novolac type epoxy acrylate. Novolak type epoxy resins having a carboxyl group such as are preferable.

The above copper clad insulating sheet is laminated on one side or both sides of an inner layer panel on which a conductor circuit pattern is formed in advance with a heat roll, an etching resist is formed on the surface copper foil, and selective etching is performed for the inner layer. Form fine holes to correspond to the specific conductor circuit pattern of the panel,
After removing the resin composition layer of the lower layer of the micro holes removed by etching with an alkaline aqueous solution and curing the resin layer, electrically conductive the conductive pattern on the inner layer panel and the surface copper foil with a conductive substance. Then, by selectively etching the surface copper foil to form a predetermined pattern, a multilayer printed wiring board having a blind via hole can be manufactured.

The second resin composition of this copper-clad insulating sheet has a large resin flow during heating and pressurization, and therefore, between the conductor circuit patterns of the inner layer panel having the conductor pattern in the laminating step and between the conductor circuit patterns and the inner layer. The resin can permeate the surface of the panel to eliminate voids. On the other hand, since the first resin composition has a small resin flow at the time of heating and pressurizing, insulation between the conductor circuit pattern surface and the surface copper foil can be obtained. It can be secured.

However, when the novolac type epoxy resin is used, the thickness when applied is not uniform,
There is a defect that the interlayer insulation resistance and heat resistance between both conductor circuits sandwiching the insulating layer obtained from the copper clad insulating sheet are poor.

As a method for solving this, it is possible to solve the above-mentioned drawbacks by using an acrylic resin and / or a methacrylic resin (hereinafter referred to as "(meth) acrylic resin") instead of a novolac type epoxy resin. The finding is that a resin composition of a first layer containing a (meth) acrylic resin and a cross-linking agent as a main component and having low fluidity during heating is formed on a roughened surface of a copper foil, and a (meth) acrylic resin is further formed on the roughened surface. The inventors have invented a copper-clad insulating sheet for a printed wiring board, which has a second layer resin composition containing a resin and a cross-linking agent as main components and having high fluidity when heated.

[0013]

However, it has been found that the following problems occur when a resin composition containing such a (meth) acrylic resin as a main component is used.

One of them is that the characteristics of the first resin composition and the second resin composition, especially the temperature conditions during lamination, change with time. That is, the copper-clad insulating sheet may be stored for a long time before being laminated on the inner layer panel, but after storage, the fluidity of the layer of the second resin composition is not sufficiently exerted, and it is necessary to raise the laminating temperature. ,
Since the temperature must be adjusted every time, the productivity is significantly reduced.

For example, a resin composition comprising 65 parts by weight of a (meth) acrylic resin and 35 parts by weight of a crosslinking agent is used as a first resin composition, and a resin comprising 30 parts by weight of a (meth) acrylic resin and 70 parts by weight of a crosslinking agent. The copper-clad insulating sheet using the composition as the second resin composition had an optimum laminating temperature of 80 ° C. immediately after preparation, but when left at room temperature for one month, the optimum laminating temperature became 90 ° C. (see below). Comparative example 2).

Another problem is that the multilayer printed circuit board completed by using the above-mentioned copper clad insulating sheet becomes fragile due to mechanical shock, temperature shock, etc., and is easily cracked when cut with a shirring or guillotine cutter. In some cases, the crack extended to the conductor circuit pattern near the cut end, and the conductor circuit pattern was broken. Further, there is a problem that cracks are generated in a cold heat temperature cycle test, a boiling test, a thermal shock test with an oil dip, and the like.

[0017]

Means for Solving the Problems The present inventors have studied the behavior of a cross-linking agent in a resin composition in order to solve the problem that the characteristics of the resin composition change with time. The resin composition of the insulating sheet contains a (meth) acrylic resin and a cross-linking agent as main components, but the second resin composition contains the cross-linking agent in order to increase fluidity during heating. It is more than the number of products, and when left for a long time before curing the resin composition, the fact that the cross-linking agent shifts from a high concentration layer to a low layer is found, and as a result of diligent study of a method for preventing it, The present invention has been completed.

Further, the same research was conducted on the mechanism of crack generation, and the hardness of the (meth) acrylic resin after curing was higher than that of the novolac type epoxy resin, and the crosslinking density could be increased only by adding an ordinary crosslinking agent. The present invention has been completed as a result of finding the fact that the above phenomenon occurs because it becomes too large and carefully studying a method for preventing it.

That is, according to the present invention, a layer of the first resin composition which is soluble in an alkaline aqueous solution and has a low fluidity when heated is formed on the roughened surface of the copper foil, and the alkali is formed on the layer. A resin composition for use in a copper-clad insulation sheet for printed wiring boards, which comprises a layer of a second resin composition that is soluble in an aqueous solution and has a high fluidity when heated, the (meth) acrylic resin and a cross-linking agent. And ((weight ratio of (meth) acrylic resin and crosslinking agent in the first resin composition) = (0.9 to 1.1) ×)
(Weight ratio of (meth) acrylic resin and cross-linking agent in the second resin composition) is a resin composition for a copper-clad insulating sheet.

When there is a large difference between the concentration of the crosslinking agent in the first resin composition and the concentration of the crosslinking agent in the second resin composition,
Since the cross-linking agent migrates over time from the one with the higher concentration to the one with the lower concentration, the characteristics of the resin composition, particularly the heating and pressurizing conditions during lamination are changed with time. Therefore, the concentrations of the cross-linking agent in the first and second resin compositions are almost the same, that is, the concentration of the cross-linking agent in the first resin composition is the same as that in the second resin composition. It is necessary that the weight ratio of the (meth) acrylic resin and the cross-linking agent in the resin composition of above does not differ by more than 10%.

When the difference is more than 10%, if the cross-linking agent is left at room temperature for 3 months, the cross-linking agent shifts from the higher concentration to the lower concentration, which makes it necessary to change the laminating temperature condition of the copper-clad insulating sheet. . Further, a part of the cross-linking agent separates and floats on the resin-side surface of the copper-clad insulating sheet, which hinders the tackiness of the layer of the resin composition and the adhesion to the inner layer panel.

It is further preferable that the amount of the cross-linking agent to be blended is not only the blending ratio with respect to the (meth) acrylic resin in both resin compositions but also the concentration itself of the cross-linking agent in both resin compositions. Moreover, it is preferable to use the same or similar kinds of (meth) acrylic resins and crosslinking agents.

According to another aspect of the present invention, a layer of the first resin composition which is soluble in an alkaline aqueous solution and has low fluidity when heated is formed on the roughened surface of the copper foil, and the layer is formed on the layer. A resin composition used for a copper-clad insulating sheet for a printed wiring board, which is formed by forming a layer of a second resin composition which is soluble in an alkaline aqueous solution and has high fluidity when heated, the acrylic resin and / or the methacrylic resin. In addition, a monofunctional and / or bifunctional acrylic acid ester and / or methacrylic ester (hereinafter, referred to as “monofunctional and / or difunctional (meth) acrylic acid” containing a cross-linking agent as a main component and as the cross-linking agent. Ester)) and trifunctional or higher-functional polyfunctional acrylic acid esters (hereinafter simply referred to as “multifunctional (meth) acrylic acid esters”). Shi A preparative resin composition.

Here, the fact that the fluidity during heating is large means that the surface of the inner layer panel having the conductor circuit pattern on the surface is
The resin composition side of the copper-clad insulating sheet is overlaid, and the resin composition is melted in the step of laminating the whole by pressing or laminating, that is, in the range of approximately 60 to 120 ° C., and easily in the conductor circuit pattern of the inner layer panel. It means that it can flow out to fill the concave portion of the pattern.

The fluidity of the first resin composition and the second resin composition used for the copper-clad insulating sheet in the present invention upon heating depends on the molecular weight of the (meth) acrylic resin, the type of the crosslinking agent,
It can be controlled by the amount of the crosslinking agent, that is, the smaller the molecular weight of the (meth) acrylic resin, the higher the fluidity before curing is used, the more the amount of the crosslinking agent is, the more the resin composition is heated. Liquidity will increase. However, as described above, it is not preferable to control the fluidity at the time of curing by adjusting the type and amount of the cross-linking agent, because of the problem of storage stability of the copper-clad insulating sheet, because of the difference in the molecular weight of the (meth) acrylic resin. Most preferably, the fluidity is adjusted.

In the copper-clad insulation sheet of the present invention, the layers of the first and second resin compositions are preferably composed mainly of a (meth) acrylic resin soluble in an alkaline aqueous solution and a cross-linking agent. According to the above, it can be obtained by blending, as an auxiliary component, necessary components selected from an active energy ray curing reaction initiator, an active energy ray curing reaction accelerator and a curing agent. Further, if necessary, a color pigment, a moisture resistant pigment, a defoaming agent, a leveling agent, a thixotropy imparting agent, a polymerization inhibitor, an anti-settling agent, etc. may be appropriately added to the above resin composition.

Examples of the (meth) acrylic resin soluble in an aqueous alkaline solution which constitutes the resin composition used in the present invention include:
(Meth) acrylic resin soluble in a non-photosensitive alkaline aqueous solution containing an alkali-soluble group such as a carboxyl group or 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 (meth) acrylic resin soluble in a photosensitive alkaline aqueous solution containing a photopolymerizable or photodimerizable photosensitive group such as a methacryloyl group (hereinafter referred to as “(meth) acryloyl group”) can be used.

The (meth) acrylic resin soluble in an aqueous alkaline solution having no photosensitivity includes acrylic acid or methacrylic acid (hereinafter referred to as "(meth) acrylic acid"), (meth) acrylic acid ester, styrene or acrylonitrile. It is obtained by copolymerizing the vinyl monomer of

Examples of the (meth) acrylic resin soluble in an aqueous alkaline solution which constitutes the resin composition used in the present invention include:
A resin having photosensitivity is desirable, and the concentration of the photosensitive group is preferably in the range of 0.1 to 10.0 meq / g, more preferably 0.3 to 8.0 meq / g, particularly preferably 0.5 to 5 It is 0.0 meq / g. If the concentration of the photosensitive group is too low, the photocurability will be poor, and if it is too high, the storage stability will be poor.

Examples of the (meth) acrylic resin having photosensitivity and soluble in an alkaline aqueous solution include a copolymer of vinyl monomer such as (meth) acrylic acid ester, styrene or acrylonitrile, and (meth) acrylic acid. A product obtained by ring-opening addition of a glycidyl group-containing unsaturated compound such as glycidyl acrylate or glycidyl methacrylate (hereinafter referred to as “glycidyl (meth) acrylate”) (hereinafter referred to as “ring-opened addition product”) is preferable.

The ring-opening adduct is a solvent (for example, ethers such as diglyme, ethyl carbitol acetate,
Ethyl cellosolve acetate, esters such as isopropyl acetate, ketones such as methyl ethyl ketone, cyclohexanone), the above copolymer is dissolved, and glycidyl (meth) acrylate as it is or diluted with a solvent and reacted under appropriate conditions can get.

At this time, a radical polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether or phenothiazine is added in an amount of 10 to 10,000 ppm, preferably 30 to 5 ppm.
000 ppm, particularly preferably 50 to 2,000 ppm
The reaction temperature is preferably room temperature to 170
° C, more preferably 40 to 150 ° C, particularly preferably 6
It is good to carry out in the range of 0 to 130 ° C. Further, as a catalyst, tetrabutylammonium bromide, a quaternary ammonium salt such as trimethylbenzylammonium chloride,
A tertiary amine such as triethylamine may be added.

When the epoxy group of glycidyl (meth) acrylate is added to the carboxyl group in the copolymer by ring-opening addition, a suitable acid value is obtained by leaving a part of the carboxyl group to obtain a polymer. Becomes alkali-soluble.
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 produced in the above reaction.

The (meth) acrylic resin constituting the first resin composition used in the present invention has a molecular weight (styrene-equivalent weight average molecular weight by gel permeation chromatography) in the range of 20,000 to 200,000. And more preferably 40,000 to 150,
It is 000. If the molecular weight is too small, the fluidity during heating will be too large, and if it is too large, the alkali solubility will be poor. Further, it constitutes the second resin composition (meta).
The acrylic resin has a molecular weight of 1,000 to 50,0.
00 is preferable, and more preferably 5,000 to 3
It is 10,000. If the molecular weight is too small, the heat resistance, water resistance, etc. will deteriorate, and if it is too large, the fluidity during heating will be too small.

The (meth) acrylic resin constituting the resin composition used in the present invention has an acid value of 0.2 to 10.0.
The range of meq / g is preferable, and more preferably 0.4 to
5.0 meq / g, particularly preferably 0.6 to 3.0 m
eq / 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.

In the resin composition used in the present invention, a photoreactive compound and / or a thermosetting resin can be used as a crosslinking agent. Examples of the photoreactive compound include acrylic type, polyether type, polyester type, unsaturated polyester type, urethane type, epoxy type, polyester / urethane type, polyacetal type and polybutadiene type. Examples thereof include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate as monofunctional (meth) acrylic acid esters; urethane acrylate and polyester as difunctional (meth) acrylic acid esters. Acrylate, 1,3-butanediol diacrylate, 1,4-
Butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, hydroxypivalate neopentyl glycol diacrylate; as polyfunctional (meth) acrylic acid esters Examples include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, and these can be used in an oligomer state. Examples of the thermosetting resin include urethane resin, epoxy resin, polyester resin, polyether resin, alkyd resin, polyvinyl chloride resin, fluororesin, silicone resin, vinyl acetate resin and polyvinyl alcohol.

The present inventors have found that when polyfunctional (meth) acrylic acid esters are used as a reinforcing cross-linking agent among the above-mentioned cross-linking agents, solder heat resistance and interlayer dielectric strength characteristics can be secured. However, when only polyfunctional (meth) acrylic acid esters are used, the crosslink density becomes too large, so that there is a problem that cracking easily occurs as described above. In order to solve this problem, the use of flexible monofunctional and / or difunctional (meth) acrylic acid esters as a crosslinking agent was also examined, but these are measures for preventing cracks, but on the other hand, The solder heat resistance was lowered, and the interlayer dielectric strength characteristics were also significantly lowered. On the other hand, in the present invention, monofunctional and / or difunctional (meth) acrylic acid esters and polyfunctional (meth) acrylic acid esters are used together as a cross-linking agent, and various properties are maintained. At the same time, it is possible to prevent cracking.

As the above-mentioned flexible monofunctional and / or bifunctional (meth) acrylic acid esters, urethane acrylate is most preferable. As other cross-linking agents, polypropylene glycol has an effect of increasing the fluidity of the resin composition after heating, and pentaerythritol triacrylate has an effect of increasing the heat resistance of the resin composition after curing.

The cross-linking agent may be one kind or two or more kinds (meta).
20 to 1 based on 100 parts by weight of the solid content of the acrylic resin
It is desirable to add 20 parts by weight. When it exceeds 120 parts by weight, the solubility in an alkaline aqueous solution is deteriorated, and a resin residue is likely to occur. If it is less than 20 parts by weight, sufficient adhesion strength between the resin composition and the outer layer copper foil cannot be obtained.

As the reaction initiator for curing active energy rays such as ultraviolet rays and electron rays, benzoin ether type benzyl, benzoin, benzoin alkyl ether, 1-
Hydroxycyclohexyl phenyl ketone; benzyl dialkyl ketal as a ketal system; 2,2′-dialicoxyacetophenone, 2-hydroxyacetophenone, pt-butyltrichloroacetophenone, pt-butyldichloroacetophenone as an acetophenone system; benzophenone as a benzophenone system , 4-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdimethylaminobenzophenone, o
-Methyl benzoylbenzoate, 3,3'-dimethyl-4
-Methoxybenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, dibenzosuberone, benzyl dimethyl ketal; thioxanthone-based thioxanthone, 2-chlorothioxanthone, 2-alkylthioxanthone, 2,4-dialkylthioxanthone, 2-alkylanthraquinone, 2,2′-dichloro-4-phenoxyacetone and the like can be mentioned, and the compounding amount thereof is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the (meth) acrylic resin solid content. If it is less than 0.5 part by weight, the reaction is not sufficiently initiated, and if it exceeds 10 parts by weight, the resin layer becomes brittle. When used by electron beam irradiation, the reaction initiator may be omitted.

As the sensitizer at the time of curing the active energy rays such as ultraviolet rays and electron beams, Nisso Cure EPA, EMA, IAMA, EHMA, MABP manufactured by Shin Nisso Kako Co., Ltd.
Kayakyu EPA, D manufactured by Nippon Kayaku Co., Ltd. such as EABP
Ward Blenkinsop, ETX, DMBI, etc.
Quantacure EPD, BEA, EOB,
Examples thereof include DMB and the like, DABA manufactured by Osaka Organic Co., Ltd., and PAA and DAA manufactured by Daito Chemical Co., Ltd. The blending amount thereof is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the (meth) acrylic resin solid content. If it is less than 0.5 part by weight, the reaction rate of active energy ray curing is not improved, and if it exceeds 10 parts by weight, the reaction becomes faster and shelf life is shortened. When used by electron beam irradiation, the reaction sensitizer may be omitted.

As the curing agent, peroxides can be used, but among them, alkyl peroxides such as dibutyl peroxide, butyl cumyl peroxide, dicumyl peroxide or 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 (meth) acrylic resin solid content. If it is less than 1 part by weight, the curing time will be long, and if it exceeds 10 parts by weight, the shelf life will be shortened and workability will be poor. A curing agent is not necessarily required when performing ultraviolet irradiation, electron beam irradiation, etc. It is preferable to add a curing agent in order to enhance adhesion stability such as adhesion stability and solder heat resistance.

In the method for producing a multilayer printed wiring board having via holes using the copper clad insulating sheet according to the present invention, when the copper clad insulating sheet is laminated on the inner layer panel, the inner layer panel and the conductor circuit pattern surface are The thickness between the surface copper foils is preferably 20 to 70 μm. 20 μm
If it is less than 7, insulation resistance and withstand voltage between layers cannot be secured, and
If it exceeds 0 μm, the undercut becomes large due to alkali dissolution at the time of forming a via hole in a small diameter hole, and sufficient connection reliability between layers cannot 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, and the resin composition of the second layer is preferably 20 to 40 μm.

The method for laminating the copper clad insulating sheet of the present invention on the inner layer panel is preferable because it can be continuously laminated by using a heat roll. The pressure during the heat roll is preferably 1 to 5 kg / cm ² in terms of air pressure.

In the method for producing a multilayer printed wiring board having a blind via hole using the copper clad insulating sheet of the present invention, the curing of the resin layer is mainly carried out by heating, but it can also be carried out by an active energy ray such as an electron beam. is there. 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. by thermosetting, the insulating resin forming the inner layer panel deteriorates, and if the temperature is less than 80 ° C., it takes a long time to cure, and the crosslinking may be insufficient, resulting in insufficient insulation resistance.

The resin composition around the via hole flows out at the time of heating, and the resin in the portion with a large amount of flow covers the surface of the conductor circuit pattern of the lower inner layer panel, so that conduction cannot be obtained even if the via hole is plated. Defects occur. Therefore, ultraviolet irradiation or electron beam irradiation is performed in a state where the resin composition starts to flow by heating, and an active energy ray is applied to the resin composition below the via hole opened in the copper foil or in the portion facing the via hole. By advancing the curing of the resin composition, it is possible to form a weir for the resin flow and prevent the resin composition from flowing more than necessary.
In the case of electron beam irradiation, 10 to 30 at 180 to 300 kV
The condition of Mrad is good, and not only the layer of the resin composition around the via hole is cured but also the layer of the resin composition under the 18-35 μm thick copper foil is cured by the electron beam penetrating the copper foil. be able to.

When laminating the copper clad insulating sheet used in the method for producing a multilayer printed wiring board having via holes using the copper clad insulating sheet of the present invention on an inner layer panel,
In order to secure the adhesive force between the resin composition and the conductor circuit pattern to be the inner layer, it is preferable to subject the surface of the circuit pattern to roughening treatment, black oxide treatment, brown oxide treatment, red oxide treatment and the like.

In the method for producing a multilayer printed wiring board having a via hole using the copper clad insulating sheet of the present invention, the layer of the resin composition for forming the via hole can be dissolved with an organic solvent, but an alkaline aqueous solution is used. It is more preferable to use it from the viewpoint of reliability of via holes and workability. This is because when the resin composition is dissolved in an organic solvent, the reaction is swelling and dissolution reaction, and the boundary of the resin after dissolution becomes rough instead of smooth, and there is a problem that the organic solvent remains near the boundary. Therefore, when the via hole obtained by dissolving the resin composition is plated, the influence of the residual organic solvent and the rough boundaries of the resin make it difficult to deposit the electroless plating, thus causing the occurrence of pinholes in the plating and the plating. The residual organic solvent evaporates even in the formed via holes, causing problems such as voids, bubbles, and blistering, which make the electrical and mechanical connections due to the via holes between the conductive circuits between layers unstable and the connection reliability Because I can't get it.

On the other hand, when the resin composition is dissolved in an alkaline aqueous solution, the carboxyl group reacts and dissolves, so that the dissolution rate is fast, and the resin is sequentially dissolved from the portion in contact with the alkaline aqueous solution, so that the boundary of the resin becomes clear. Become. In addition, if the resin is dissolved in an alkaline aqueous solution and then washed with an acid, the alkaline component does not remain, the deposition of the electroless plating afterwards is good, and defects such as voids, bubbles, and blisters do not occur, so that reliability is improved. High via holes can be formed.

Further, it is more preferable in that a multilayer printed wiring board having a via hole can be easily manufactured in the conventional manufacturing process of a printed wiring board without deteriorating the working environment like an organic solvent. That is, if an alkali-soluble etching resist is used to form a via hole in a copper foil, a resin composition layer under the copper foil via hole is formed simultaneously with the resist in the film stripping step after copper foil etching. Can be dissolved. Further, when the alkali development type dry film is used as a resist, it is more preferable that the resin layer in the lower part of the copper foil via hole can be dissolved and removed at the same time as the removal of the resist with a sodium hydroxide aqueous solution for stripping.

When a resin composition having an alkali-soluble group such as a carboxyl group is dissolved in an aqueous alkaline solution, the alkali component that has reacted with the carboxyl group remains,
Since there is a risk of corrosion of copper and deterioration of electrical characteristics, it is desirable to carry out acid cleaning with diluted sulfuric acid or the like after dissolution. When the copper wiring pattern of the inner layer panel is blackened, if the via holes are neutralized with an acid, the blackened oxide film is dissolved and copper color is produced. When the resin remains on the surface of the blackening treatment film, the color of copper cannot be seen, and therefore the quality of the alkali dissolution can be judged by this neutralization treatment.

In the production of a multilayer printed wiring board having a blind via hole using the copper clad insulating sheet of the present invention, a copper foil is etched to form fine holes, and a resin composition under the fine holes is formed with an alkaline aqueous solution. As a method of electrically connecting the exposed conductor circuit pattern of the inner layer panel to the surface copper foil by electrolysis, electroless plating or / and electrolytic plating, and a conductive paste such as gold, silver, copper, or solder. Can be applied by screen printing, dispenser, pin printing and the like, followed by drying and curing.

The copper-clad insulation sheet of the present invention is a copper-clad insulation sheet in which a layer of the first resin composition and a layer of the second resin composition are formed on the copper foil so that the multilayer printed wiring board can be continuously manufactured. It is preferable to wind the sheet in a roll shape via a release film or release paper because the rolled copper-clad insulating sheet can be continuously laminated on the inner layer panel with a hot roll.

The copper-clad insulating sheet of the present invention has the first and second resin composition layers formed on the mat surface of the copper foil,
It is also possible to apply a photosensitive resin in advance on the copper foil opposite to the copper foil. The photosensitive resin can be used in place of the dry film or the etching resist after laminating the copper clad insulating sheet on the inner layer panel, and the step of forming the dry film or the etching resist can be omitted in the manufacturing process of the multilayer printed wiring board. . Not only the economic efficiency is improved, but also the yield is improved by using this method, so that it can be superior in terms of quality.

[0056]

EXAMPLES Examples 1 to 7 (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, A mixture consisting of 1 part by weight of azobisisobutylnitrile was added dropwise to 120 parts by weight of propylene glycol monomethyl ether kept at 80 ° C. in a nitrogen gas atmosphere over 5 hours. Then, after aging for 1 hour, 0.5 parts by weight of azobisisobutylnitrile was further added and aging for 2 hours to synthesize a carboxyl group-containing methacrylic resin. 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 50,000. ~ 70,000, acid value 1.2 meq
/ G, unsaturated equivalent 1.14 mol / kg of a base resin having a carboxyl group was synthesized.

Synthesis Example 2 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, 2 parts by weight of azobisisobutylnitrile and a chain transfer agent. A mixture of 2 parts by weight of dodecyl mercaptan was added dropwise to 120 parts by weight of propylene glycol monomethyl ether kept at 90 ° C. in a nitrogen gas atmosphere over 5 hours. Thereafter, after aging for 1 hour, 1 part by weight of azobisisobutylnitrile was further added and aging was performed for 2 hours to synthesize a carboxyl group-containing methacrylic resin. 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 100 ° C. for 8 hours to give a molecular weight of 6,000. ~ 8,000, acid value 1.2 meq /
g, unsaturated equivalent 1.14 mol / kg of a base resin having a carboxyl group was synthesized.

(Preparation of Resin Composition) Using the base resin of Synthesis Example 1 prepared as described above, the type and amount of the crosslinking agent and the curing agent (Perky Mill D manufactured by NOF CORPORATION) shown in Table 1 were often used. The first resin composition was prepared by mixing. Also, using the base resin of Synthesis Example 2 produced as described above,
The type and amount of the crosslinking agent and the curing agent shown in Table 1 (Perky Mill D manufactured by NOF CORPORATION) were thoroughly mixed to prepare a resin composition for the first layer. These are Examples 1 to 6 and Comparative Example 1
And

(Production of Multilayer Printed Wiring Board) A method for producing a multilayer printed wiring board having via holes using the copper clad insulating sheet of the present invention will be described with reference to the drawings. 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 structure of a multilayer printed wiring board using the copper-clad insulating sheet of the present invention. Is.

The resin composition of the first layer was coated on the matte surface of the copper foil having a thickness of 35 μm, which had been subjected to the mat treatment, with a comma coater and dried at 60 ° C. for 20 minutes to form a resin layer having a thickness of 70 μm.

The resin composition of the second layer is similarly applied and dried on the resin layer of the first layer to form a resin layer of 30 μm,
A copper clad insulating sheet as shown in FIG. 1 was created. The obtained copper-clad insulation sheet of each Example was left in a high temperature bath at 40 ° C. for one month, but no change was observed and the optimum laminating temperature did not change from the initial 80 ° C.

An inner layer panel 7 was prepared by forming a copper wiring pattern 6 at a predetermined position on a 0.6 mm thick glass epoxy double-sided copper clad plate having a 35 μm copper foil 4 as an inner layer panel by selective etching. The surface of the copper wiring pattern 6 of the inner layer panel 7 is 37 g of sodium chlorite /
The solution was treated with a solution consisting of liter, 10 g / liter of sodium hydroxide and 20 g / liter of trisodium phosphate dodecahydrate at 95 ° C. for 5 minutes, thoroughly washed with water, dried and then blackened.

Next, the copper-clad insulating sheets 1 are laid on both sides of the inner layer panel 7 (FIG. 1), and the air pressure is set to 3 kg / cm ² for 1
Lamination with a 50 mm metal roll was carried out to produce a copper clad laminate panel incorporating the inner layer panel. Here, the optimum laminating temperature was 80 ° C. In this step, the layer 3 of the second resin composition has a large fluidity and therefore flows into the space between the copper wiring patterns 6, and the layer 2 of the first resin composition has almost no resin flow and thus contacts the copper wiring pattern 6 of the lower layer. A copper clad laminate panel as shown in FIG. 2 was produced.

Alkali-soluble type by a screen printing method or a photo method on a portion of the surface of the copper foil 4 of the above copper clad laminate panel except a portion where the copper foil via hole 8 of 0.3 to 0.5 mmφ is formed. The etching resist of 1 was formed, and the copper in the via holes of the copper foil was etched with a cupric chloride solution (FIG. 3). Followed by 1 wt% sodium carbonate solution 40 ° C. at a spray pressure of 1.5 kg / cm ^2, dissolve and remove the layer 2 of the first layer of the resin composition of the underlying portion of the via hole 8 of the copper foil Then, the copper wiring pattern 6 of the lower layer is exposed to form a blind via hole 9, and then 2
The etching resist was removed with a weight% sodium hydroxide solution (FIG. 4).

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. Then, after preheating at 100 ° C. for 30 minutes and aging at 150 ° C. for 45 minutes to cure the layer 2 of the first resin composition and the layer 3 of the second resin composition, as shown in FIG. The through hole 10 that requires connection between the copper wiring pattern 6 of the panel for use and the copper foil 4 of the outer layer is drilled, and the blind via hole and the through hole are plated at the same time as shown in FIG. An etching resist 12 was formed as shown in FIGS. 8 and 9, and etching and film stripping were performed to obtain a multilayer printed wiring board having a blind via hole.

Evaluation of crack generation at the time of cutting the printed wiring board prepared as described above with a guillotine cutter, -6
Cracking evaluation by a thermal cycling test with 5 ° C 30 minutes and 125 ° C 30 minutes as one cycle, solder heat resistance test evaluation at 280 ° C for 3 minutes with a 25 mm square pattern, crusher cooker test (130 ° C, 85% RH, 100 hours, Table 1 shows the results of the evaluation of the inter-layer withstand voltage by DC20V bias).

[0067]

[Table 1]

The evaluation criteria for each test shown in Table 1 are as follows. Cracks during cutting and thermal cycling are
(No occurrence), △ (slightly occurred), × (large occurrence). Soldering heat resistance is ○ (all 180 seconds or more OK), △ (30-18
0 seconds), × (Blistering occurs within 30 seconds). Interlayer withstand voltage: ○ (no abnormality), △ (some abnormal appearance), ×
(Abnormal appearance, insulation deterioration of 2 digits or more).

As is clear from Table 1, when pentaerythritol triacrylate (Aronix M-305 manufactured by Toagosei Kagaku Kogyo Co., Ltd.) was blended as the polyfunctional (meth) acrylic acid ester, solder heat resistance and The interlayer dielectric strength is good, but cracks easily occur. Monofunctional 2-hydroxy-3-phenoxypropyl acrylate (the same Aronix M-5700), bifunctional tetraethylene glycol diacrylate (the same)
Aronix M-240) and polyester acrylate (Aronix M-6400) alone reduce cracking but tend to deteriorate soldering heat resistance or interlayer dielectric strength. These are improved by combining with a trifunctional cross-linking agent, but still unsatisfactory results are obtained. On the other hand, urethane acrylate (the same Aronix M-1600)
The above alone had a large crack-preventing cure, and when combined with a trifunctional crosslinking agent, the effect was even greater.

Comparative Example 1 For example, a resin composition containing 65 parts by weight of the base resin of Synthesis Example 1, 35 parts by weight of a cross-linking agent (Aronix M-305) and 1.5 parts by weight of a curing agent (Perk Mill D) was used as a first composition. A copper-clad insulating sheet having a resin composition of 30 parts by weight of the base resin of Synthesis Example 1, 70 parts by weight of Aronix M-305 and 1.5 parts by weight of Perkmill D as the second resin composition is used as the resin composition. The optimum laminating temperature immediately after preparation was 80 ° C, but when left at room temperature for 1 month, the optimum laminating temperature became 90 ° C.

[0071]

According to the copper clad insulating sheet of the present invention, a multilayer printed wiring board having a blind via hole having excellent physical properties, electrical properties and reliability can be obtained. Moreover, since blind via holes and through via holes can be easily and collectively formed by etching copper foil and dissolving resin with an alkaline aqueous solution, productivity is improved compared to the conventional drilling process in which holes are drilled. Is greatly improved. Also, regardless of variations in the depth of the inner layer copper foil pattern, it is possible to reliably form the blind hole by dissolving the resin layer up to the inner layer copper foil pattern. There is no hole connection defect, and there is no short circuit defect that is erroneously connected to the copper foil pattern of the other layer for the inner layer. Further, since the prepreg used between the inner layer panel and the outer copper foil can be reduced, the thickness of the printed wiring board can be reduced, so that a high-density multilayer printed wiring board can be obtained. Therefore, it is extremely useful because it enables the manufacture of a multilayer printed wiring board which requires blind via holes used for high-density mounting in various electronic devices.

[Brief description of drawings]

FIG. 1 shows a configuration before thermocompression bonding of an inner layer panel having a copper wiring pattern on its surface and a copper clad insulating sheet in the manufacturing process of a multilayer printed wiring board having a via hole using the copper clad insulating sheet of the present invention. It is the schematic sectional drawing shown.

FIG. 2 is a schematic cross-sectional view showing a configuration of an inner layer board panel after being laminated in the manufacturing process.

FIG. 3 is a schematic cross-sectional view showing the inner layer board panel after forming an etching resist on the copper foil on the surface in the same manufacturing process.

FIG. 4 is a schematic cross-sectional view showing the inner layer board panel after a blind via hole is formed in a copper foil on the surface by etching in the same manufacturing process.

FIG. 5 is a schematic cross-sectional view of the inner layer board panel after the resin layer under the copper foil blind via hole is melted and the resin in the through hole is melted to form an access hole-shaped through via hole in the manufacturing process. It is a figure.

FIG. 6 is a schematic cross-sectional view after forming a conductive paste in the manufacturing process.

FIG. 7 is a schematic cross-sectional view after forming an etching resist for etching the outer layer copper foil pattern in the manufacturing process.

FIG. 8 is a schematic cross-sectional view after the unnecessary copper foil of the outer layer is etched and the etching resist is removed in the same manufacturing process.

FIG. 9 is a schematic cross-sectional view after forming a solder resist in the same manufacturing process.

FIG. 10 is a schematic cross-sectional view showing a structure before thermocompression bonding of an inner layer panel having a copper wiring pattern on its surface and a copper foil through a prepreg in a manufacturing process of a conventional multilayer printed wiring board having a blind via hole. It is a figure.

FIG. 11 is a schematic cross-sectional view showing the configuration of a copper clad laminate panel after being subjected to thermocompression bonding in the same manufacturing process.

FIG. 12 is a schematic cross-sectional view showing the copper clad laminate panel after forming blind via hole holes by drilling in the same manufacturing process.

FIG. 13 is a schematic cross-sectional view showing the copper clad laminate panel after forming through holes by drilling in the same manufacturing process.

FIG. 14 is a schematic cross-sectional view after a plating process in the manufacturing process.

FIG. 15 is a schematic cross-sectional view after forming an etching resist in the manufacturing process.

FIG. 16 is a schematic cross-sectional view after unnecessary copper foil is removed by etching in the manufacturing process.

FIG. 17 is a schematic cross-sectional view after removing the etching resist in the same manufacturing process.

[Explanation of symbols]

 1 Copper Clad Insulation Sheet 2 First Layer Resin 3 Second Layer Resin 4 Copper Foil 5 Prepreg 6 Conductor Circuit Pattern (Copper Wiring Pattern) 7 Inner Layer Panel 8 Copper Foil Via Hole 9 Blind Via Hole 10 Through Hole 11 Plating through hole 12 Etching resist 13 Via hole hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenya Matsumoto Kenya Matsumoto, Aichi Prefecture 1-chome, Funami-cho, Minato-ku, Tochi Gosei Chemical Industry Co., Ltd. Nagoya Research Institute (72) Inventor Tomio Kanbayashi Nagoya, Aichi Prefecture 1 Toago Synthetic Chemical Industry Co., Ltd., Nagoya Research Institute, Minami-ku Funami-cho (72) Inventor Hitoshi Kato 1 Toa Synthetic Chemical Industry Co., Ltd. Nagoya Research Institute, 1-Funami-cho, Minato-ku, Nagoya, Aichi Prefecture (72) Inventor Hattori Takehisa 1 Touna Synthetic Chemical Industry Co., Ltd.

Claims (2)

[Claims] 1. A layer of a first resin composition, which is soluble in an alkaline aqueous solution and has low fluidity when heated, is formed on a roughened surface of a copper foil and is soluble in the alkaline aqueous solution on the layer. A resin composition for use in a copper-clad insulating sheet for a printed wiring board, which comprises a layer of a second resin composition having high fluidity when heated, and which mainly comprises an acrylic resin and / or a methacrylic resin and a crosslinking agent. And (the weight ratio of the acrylic resin and / or methacrylic resin in the first resin composition to the crosslinking agent) = (0.9 to 1.1) × (acrylic resin in the second resin composition and / or A weight ratio of methacrylic resin to a cross-linking agent), the resin composition for a copper-clad insulating sheet. 2. A layer of a first resin composition, which is soluble in an alkaline aqueous solution and has low fluidity when heated, is formed on a roughened surface of a copper foil, and is soluble in the alkaline aqueous solution on the layer. A resin composition for use in a copper-clad insulating sheet for a printed wiring board, which comprises a layer of a second resin composition having high fluidity when heated, and which mainly comprises an acrylic resin and / or a methacrylic resin and a crosslinking agent. As a component and as a cross-linking agent, monofunctional and / or difunctional acrylic acid esters and / or methacrylic esters, and trifunctional or higher polyfunctional acrylic acid esters and / or methacrylic esters are used in combination. A resin composition for a copper-clad insulating sheet, comprising: