JPH0748109B2 - Photosensitive resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photosensitive resin composition, and more specifically, for forming an interlayer insulating film having excellent adhesion with a plating film that can be used for producing a multilayer printed wiring board. Of the photosensitive resin composition.

(Prior Art) In recent years, in a printed wiring board, a multilayer printed wiring board in which wiring circuits are formed in multiple layers is used for the purpose of increasing the density.

Conventionally, as a multilayer printed wiring board, a multilayer printed wiring board is used in which a plurality of circuit boards on which inner layer circuits are formed are laminated and pressed by using a prepreg as an insulating layer and bonded, and then each inner layer circuit is connected by through holes. It was

However, in such a multilayer printed wiring board, since a desired inner layer circuit is connected by forming a through hole penetrating the wiring board, each inner layer circuit becomes a complicated circuit that bypasses a through hole that does not need to be connected, It has been difficult to densify the circuit.

As a multilayer printed wiring board that can solve this difficulty, development of a multilayer printed wiring board in which conductor circuits and organic insulating layers are alternately built up has recently been actively pursued. This multilayer printed wiring board is suitable for ultra-high density, but it is difficult to form an organic insulating layer that can firmly adhere the plating film, so the conductor of this type of multilayer printed wiring board is difficult to form. The circuit is formed by the PVD method or a combination of the PVD method and the plating method. However, the conductor circuit formation by such PVD method,
It has the drawbacks of low productivity and high cost. Therefore, development of a photosensitive resin composition capable of forming an organic insulating layer capable of firmly adhering a plating film has been awaited.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to form an organic interlayer insulating layer which is excellent in heat resistance and electrical insulation and which can firmly adhere a plating film. Another object of the present invention is to provide a photosensitive resin composition that can be used.

(Means for Solving the Problem) As a result of earnest research, the present inventor has found that a photosensitive resin composition based on a (meth) acrylate of an epoxy resin represented by Formula 1, which is excellent in both heat resistance and flexibility. , And further contains a fine particle filler that can be dissolved and removed by chemical conversion treatment, and the surface of the insulating layer is subjected to chemical conversion treatment to dissolve and remove the fine particle filler to roughen the insulating layer surface, We have succeeded in remarkably improving the adhesion strength with the plating film formed above, and have solved the above problems. That is,
The present invention includes (a) a compound represented by Formula 1 (n is O or more)
(B) a photopolymerizable compound in which at least one epoxy group is (meth) acrylic modified with at least one of
A polymerizable compound having at least two terminal ethylene groups, (c) a photopolymerization initiator that generates radicals by actinic rays, (d) an epoxy curing agent, (e) an oxide fine particle filler, (f) ) A photosensitive resin composition containing heat-resistant resin fine particles which can be dissolved and removed by an oxidizing agent.

Formula 1 The photosensitive resin composition of the present invention contains, as an essential component, at least one compound represented by Formula 1 (n is 0 or more) and a photopolymerizable compound in which at least one epoxy group is (meth) acryl-modified. To do. Formula 1 used in the present invention
The epoxy resin shown in is generally phenol and aralkyl ether (αα′-dimethoxyparaxylene).
It is produced by reacting phenol aralkyl obtained by condensing and by a Friedel-Crafts reaction with epichlorohydrin in the presence of an alkali. Here, the number of n is preferably 2 or more, and more preferably 4 or more. When n is 1 or less, tack does not completely disappear during drying, and when it is used as a photosensitive material, for example, when image exposure is performed by a contact method, it adheres to a photomask film and it is difficult to obtain a smooth surface. This is due to the fact that it has low resistance to, and the surface of the insulating layer may be eroded.

However, since this problem can be solved by selecting the exposure method and the development method, the number of n is not particularly limited.

Next, the epoxy resin represented by Formula 1 is (meth) acrylic-modified with acrylic acid or methacrylic acid to obtain an essential component (hereinafter referred to as essential component (a)). As acrylic acid or methacrylic acid used here, generally known ones can be used, but it is desirable to use acrylic acid from the viewpoint of sensitivity and resolution. In the present invention, the degree of (meth) acryl modification is such that at least one or more epoxy groups are (meth) acryl modified, but preferably two or more epoxy groups are (meth) acryl modified. It is preferable. This is because when the number of n is small and the degree of this (meth) acrylic modification is small, the photo-cured film is likely to swell and peel off by the development treatment after image exposure.

The photosensitive resin composition of the present invention contains, as an essential component, a polymerizable compound having at least two terminal ethylene groups (hereinafter referred to as essential component (b)). As this compound, generally known compounds can be used. For example, dipentaerythritol hexaacrylate, 1,6-hexanediol acrylate, tris (2-acryloxyethyl) isocyanurate, neopentyl glycol diacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, diallyl terephthalate,
N, N'-methylenebisacrylamide and the like can be mentioned.
To 100 parts by weight of the photopolymerizable compound of the essential component (a),
When the amount of the polymerizable compound as the essential component (b) used is 1 part by weight or less, the heat resistance of the cured film decreases, and when it is 30 parts by weight or more, the thermal shock resistance deteriorates. Therefore, the amount of the polymerizable compound as the essential component (b) used is 1 to 30 parts by weight, preferably 5 to 20 parts by weight, relative to 100 parts by weight of the essential component (a).

The photosensitive resin composition of the present invention contains, as an essential component, a photopolymerization initiator that generates radicals by actinic rays (hereinafter referred to as an essential component (c)). As the photopolymerization initiator, conventionally used photopolymerization initiators can be used. For example, benzophenone, 1-hydroxycyclohexyl phenyl ketone, benzyl dialkyl ketal, 2-hydroxy-2-methyl propiophenone, Michler's ketone, benzoin ethyl ether, 2,4-dialkylthioxanthone, 2-methyl-1 [4- (methylthio) Phenyl] -2-morpholinopropanone and the like.
Further, the rate of photopolymerization initiator may be combined with a sensitizer having a different absorption wavelength of actinic rays to improve the efficiency of polymerization initiation and increase the sensitivity higher than the sensitivity. Examples thereof include a combination of benzophenone and triethanolamine, 2-methyl-1 [4-methylthio) phenyl] -2-morpholinopropane and thioxanthone, benzyldialkylketal and Michler's ketone, and the like. The amount of the initiator of the essential component (c) is 0.1 with respect to 100 parts by weight of the total amount of the photopolymerizable compound of the essential component (a) and the polymerizable compound of the essential component (b).
-20 parts by weight, preferably 1-15 parts by weight.

The photosensitive resin composition of the present invention contains 1 to 10 parts by weight of an epoxy curing agent as an essential component (hereinafter, essential component (d)).
Called). Examples of the epoxy curing agent include imidazoles such as 1-methylimidazole, 1-phenylimidazole and 1-benzyl-2-methylimidazole, 1,3
-Bis (hydrazinocarboethyl) -5-isopropylhydantoin, boron trifluoride monoethylamine, adipic acid, dihydrazide, dicyandiamide and the like. However, it is preferable to use imidazoles or dicyanamide from the viewpoint of electrical characteristics.

The photosensitive resin composition of the present invention contains an oxide fine particle filler (hereinafter referred to as an essential component (e)) as an essential component. Examples of such fillers include silica, alumina and talc. The particle size of the fine particle filler is preferably 0.01-from the viewpoints of resolution, adhesion of the cured film, etc.
It is 15 μm, more preferably 0.01 to 2.5 μm. The amount of the fine particle filler of the essential component (e) used is 10 to 60 parts by weight based on 100 parts by weight of the total amount of the essential component (a) and the essential component (b). The fine particle filler is preferably uniformly dispersed in the photosensitive resin composition, and therefore the surface of the fine particle filler can be treated with a coupling agent having a functional group such as an amino group and a hydroxyl group. . Examples of the coupling agent include γ-aminopropyltriethoxysilane, β-aminoethyl-γ-aminopropyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

The photosensitive resin composition of the present invention uses heat-resistant resin fine particles that have been previously cured as an essential component (f). The reason for using the heat-resistant resin fine particles that have been pre-cured is that when the heat-resistant resin fine particles that are not pre-cured are used, they dissolve in the resin liquid when dispersed in the photosensitive resin composition. This makes it impossible to selectively remove by dissolution. If the heat-resistant resin fine particles that have been previously cured are used, they do not dissolve in the resin liquid even when dispersed in the photosensitive resin composition, and an insulating layer in which the heat-resistant resin fine particles are uniformly dispersed can be formed. By subjecting this insulating layer to chemical conversion treatment to dissolve and remove the heat-resistant resin fine particles, the surface of the insulating layer can be uniformly roughened, and a plated film can be formed on the insulating layer with high reliability.

The material of the heat-resistant resin fine particles is a resin having excellent heat resistance and electrical characteristics, which does not dissolve even when dispersed in a photosensitive resin composition by a curing treatment, and has a property of being dissolved in a specific chemical liquid used for chemical conversion treatment. However, an epoxy resin, a polyester resin, a bismaleimide-triazine resin or the like can be used. Examples of the curing method include a method of curing by heating and a method of adding a catalyst to cure. Examples of the oxidant include chromic acid, chromate,
Permanganate or the like can be used.

The heat-resistant resin fine particles preferably have a particle size of 15 μm or less, more preferably 5 μm or less. The reason is that the roughened surface formed by dissolving and removing the fine particles having a particle size of 15 μm or more becomes nonuniform, so that the plated film cannot be reliably formed. The amount of the fine particle filler which can be dissolved and removed by the chemical conversion treatment of the essential component (f) is 10 to 60 parts by weight based on 100 parts by weight of the total amount of the essential component (a) and the essential component (b).

Further, the photosensitive resin composition of the present invention may contain other subsidiary components. Examples of the secondary component include a thermal polymerization inhibitor, a pigment, a color former, a coatability improving agent, a defoaming agent, an adhesion improving agent, and a leveling agent.

Also, if necessary, bisphenol A type epoxy resin,
Various epoxy resins such as novolac type epoxy resin and cycloaliphatic epoxy resin can be used together.

The photosensitive resin composition of the present invention can be applied onto a substrate by a conventional method such as a dip coating method, a flow coating method, or a screen printing method. If necessary, the composition may be diluted with a solvent before application. Examples of the solvent include butyl cellosolve, methyl cellosolve acetate, butyl cellosolve acetate, methyl ethyl ketone, cyclohexanone and the like.

(Effect of the Invention) The photosensitive resin composition of the present invention has a high heat resistance because the skeleton of the photopolymerizable compound constituting the main part is formed by an aromatic ring, but it is an epoxy that serves as a crosslinking point. Since the groups are present every other aromatic ring, the crosslink density is low and the flexibility is high. This is particularly flexible when compared with the cresol novolac type epoxy resin, which is the skeleton of the photopolymerizable compound that constitutes the main part of the photosensitive resin composition for forming a protective film that is used in the production of conventional printed wiring boards. Differences in sex become apparent.

Further, the oxide fine particle filler contained in the photopolymerizable compound or the like suppresses thermal expansion of the insulating layer and makes the adhesive property with the underlying conductor excellent.

Furthermore, since the photosensitive resin composition contains heat-resistant resin fine particles that can be dissolved and removed by an oxidizing agent, by treating the cured film of the photosensitive resin composition with an oxidizing agent, minute irregularities are formed on the surface of the cured film. It is formed. When plating is performed on such a surface, a plating film is formed even on the details of the minute irregularities. If the plating film is to be peeled off, the minute irregularities will be caught and will act as a so-called anchor.

Further, when the plating film is peeled off, since the minute irregularities act as anchors, the breaking strength of the cured film controls the peeling strength of the plating film. At this time, the cured product of the photopolymerizable compound constituting the main part of the photosensitive resin composition of the present invention is excellent in flexibility as compared with the cured product of a usual cresol novolac type epoxy resin, When the plating film is peeled off, destruction occurs at a deep position of the cured film, and the adhesive strength is increased accordingly.

In this way, the plating film formed on the cured film of the photosensitive resin composition of the present invention firmly adheres, and the effect of the present invention by the photosensitive resin composition occurs.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these. Parts used as numerical units in the examples mean parts by weight.

Further, the following Expression 1 is represented by the following expression.

Formula 1 Reference Example 1 Phenol aralkyl type epoxy resin shown in Formula 1 (manufactured by Mitsui Toatsu Chemical Co., Inc., prototype No .: JE-325, containing about 60% of n = 0 component)
Content, epoxy equivalent 223) 223 parts, acrylic acid 36 parts, benzyldimethylamine 0.6 parts, phenothiazine 0.06 parts with stirring and dissolution in butyl cellosolve acetate 170 parts, while blowing air into the reaction system at 100 to 110 ° C for 20 hours. Reacted The acid value of the reaction product was measured, and the point at which the acid value became 0.5 or less was set as the end point.

Reference Example 2 260 parts of phenol aralkyl type epoxy resin shown in Formula 1 (manufactured by Mitsui Toatsu Chemical Co., Inc., prototype number: XED-M, n = 4 to 8, epoxy equivalent 260), 72 parts of acrylic acid, 1.3 parts of benzyldimethylamine, Phenothiazine (0.13 parts) was dissolved in butyl cellosolve acetate (220 parts) with stirring, and reacted at 100 to 110 ° C for 20 hours while blowing air into the reaction system. The acid value of the reaction product was measured, and the point at which the acid value became 0.5 or less was set as the end point.

Example 1 1). 100 parts of 50% acrylated product of phenol aralkyl type epoxy resin synthesized in Reference Example 1, 15 parts of diallyl terephthalate, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1 (Ciba. Made by Geigy, trade name: Irgacure 907) 4 copies,
Imidazole (Shikoku Kasei) trade name: 2P4MHZ) 4 parts, silica fine powder (Nippon Shokubai Kagaku Kogyo, trade name: NS Silica X)
-05, average particle size 0.5 μm) 25 parts, epoxy resin fine powder (manufactured by Toray, trade name: Trepearl EP-B, average particle size 0.5 μ)
m) After mixing 25 parts, while adding butyl cellosolve, the viscosity was adjusted to 250 cps with a homodisper stirrer, and then kneaded with three rolls to prepare a solution of the photosensitive resin composition.

2). Then, a solution of the photosensitive resin composition was applied onto a printed wiring board obtained by photoetching the surface of the copper-clad laminate by a conventional method using a knife coater, and allowed to stand in a horizontal state for 20 minutes, then at 70 ° C. Dry with touch with a thickness of about 50μ
m photosensitive resin layer was formed.

3) Next, a photomask film on which a 100 μmΦ black circle is formed is adhered to it, and 500 mj / cm with an ultra-high pressure mercury lamp.
² exposed. This was subjected to ultrasonic development treatment with a chlorocene solution to form a 100 μmΦ via hole on the printed wiring board. Then, this wiring board was exposed with an ultra-high pressure mercury lamp at about 3000 mj / cm ² and further exposed at 100 ° C. for 1 hour and then 150
By heat treatment at ℃ for 10 hours, an interlayer insulating film with via holes corresponding to a photomask film and excellent in dimensional accuracy was obtained.

4). Next, apply this interlayer insulation film to a temperature of 70 ° C and a concentration of 500g.
It is roughened with / l chromic acid for 15 minutes, immersed in a neutralizing solution (made by Shipley, product name / PM950) and washed with water. Since this coating contains silica fine particles insoluble in chromic acid and epoxy resin fine particles soluble in chromic acid, a very complicated roughened surface was obtained by treating the surface of the coating with chromic acid.

5). Then, as a pretreatment for chemical plating, a palladium catalyst (trade name: Cataposit 44, manufactured by Shipley Co., Ltd.) is applied to activate the surface, and after immersion in a chemical copper plating solution of the following composition for 15 minutes, electrolytic copper plating of the following composition When 20 μm of copper was deposited in the via hole by the liquid, the peel strength in the normal state was 2.00 kg / cm. In addition, MIL-STD-202 Met
In a thermal shock test according to hod 107 Condition B, it became clear that no disconnection occurred even after 500 cycles and that long-term reliability was excellent. Further, diallyl terephthalate contained in the resin solution increases the crosslink density during curing,
The cured film had excellent heat resistance, and was subjected to a solder heat resistance test at 260 ° C for 30 seconds, but no peeling or discoloration of the insulating layer film was confirmed.

Chemical copper plating solution composition Shipley 328A 12.5% 〃 328L 12.5% 〃 328C 1.5% Pure water 73.5% Temperature 25 ℃ Electrolytic copper plating solution composition CuSO ₄・ 5H ₂ O 150g / l H ₂ SO ₄ 40g / l Cl 20ppm Additive Predetermined amount Temperature 25 ° C Cathode current density 2A / dm ^{2 In} the photosensitive resin composition of this example, the photopolymerizable compound used as an essential component is excellent in heat resistance and flexibility. , Since it contains silica fine particles insoluble in chromic acid and epoxy resin fine particles soluble in chromic acid, the roughened surface shape becomes very complicated and high adhesion can be obtained when a conductor is formed on the insulating layer. Since the inorganic fine silica particles are included, the insulating film has high hot hardness, and thermal expansion is suppressed, so that the thermal shock resistance is excellent.

Example 2 1). 60 parts of 100% acrylated product of phenol aralkyl type epoxy resin synthesized in Reference Example 2, 40 parts of bisphenol A type epoxy resin (manufactured by Yuka Shell, trade name: Epicoat 1001), 15 parts of diallyl terephthalate, 2-hydroxy-2 -2 methyl propiophenone (Merck & Co., trade name: Darocur 1173) 4 parts, 1,3-bis (hitoradi) carboethyl) -5-isopropylhydrontoin (Ajinomoto, trade name: Amicure VDH) 30 parts, 25 parts of talc fine powder (manufactured by Fuji Talc Industry Co., Ltd., trade name: LMS # 200, average particle size 1.5 μm), 35 parts of epoxy resin fine powder (manufactured by Toray, trade name: Trepearl EP-B, average particle size 0.5 μm) While adding the mixed butyl cellosolve, the viscosity was adjusted to 250 cps with a homodisper stirrer, and then kneaded with three rolls to prepare a solution of the photosensitive resin composition.

2). Then, a solution of the photosensitive resin composition was applied onto a printed wiring board obtained by photoetching the surface of the copper-clad laminate by a conventional method using a knife coater, and allowed to stand in a horizontal state for 20 minutes, then at 70 ° C. 50 μm thick by touch-drying
To form a photosensitive resin layer.

3). Next, a photomask film with a 100 μmΦ black circle formed on it was adhered to it, and about 400 m with an ultra-high pressure mercury lamp.
It was exposed to j / cm ² . This was subjected to ultrasonic development treatment with a chlorocene solution to form a 100 μmΦ via hole on the printed wiring board. Then, this wiring board was exposed with an ultra-high pressure mercury lamp for about 3000 mj / cm ² and further heat-treated at 100 ° C. for 1 hour and then at 150 ° C. for 10 hours to obtain a dimensional accuracy having a via hole corresponding to a photomask film. An excellent interlayer insulating film was obtained.

4). Then, this interlayer insulating film was roughened with chromic acid according to the method of Example 1, thinned with chemical copper plating, and further, when copper of 20 μm was deposited in the via hole by electrolytic copper plating, the peel strength in the normal state was It was 2.2 kg / cm.

Since the photosensitive resin composition of this example uses Epicoat 1001 as a bisphenol A type epoxy resin in addition to the photopolymerizable compound used as an essential component, it has higher flexibility than Example 1. , When a conductor is formed on this insulating layer, high adhesion is obtained, and the curing rate is 1,3-bis (human radinocarboethyl) -5-isopropylhydontonin as an epoxy curing agent. Fast, the final heating is sufficient for 1 hour and the productivity is significantly improved, the heat resistance of the cured product is excellent because it contains diallyl terephthalate, and it is soluble in chromic acid-insoluble talc fine particles and chromic acid. Since it contains various epoxy fine particles,
Since the roughened surface forms very complicated unevenness, when a conductor is formed, it is characterized in that high adhesion can be obtained.

(Effects of the Invention) When the interlayer insulating film obtained by using the photosensitive resin composition of the present invention is used, the adhesion between the conductor circuit made of the plating film and the insulating layer is extremely excellent, and the heat resistance and thermal shock resistance are excellent. An excellent super high density multilayer wiring board can be made.

Claims (1)

[Claims] 1. A photosensitive resin composition used for adhesion to a plated coating of a multilayer printed wiring board, characterized by comprising the following (a) to (f): (A) at least one compound represented by Formula 1 (n is 0 or more) and at least one epoxy group (meta)
Acrylic modified photopolymerizable compound. Formula 1 (B) A polymerizable compound having at least two terminal ethylene groups. (C) A photopolymerization initiator that generates radicals by actinic rays. (D) Epoxy curing agent. (E) Oxide fine particle filler. (F) Heat-resistant resin fine particles that can be dissolved and removed with an oxidizing agent.