JPH0721032B2 - Photosensitive resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photosensitive resin composition, and more particularly to a photosensitive resin composition for forming an interlayer insulating film which can be used for producing a multilayer printed wiring board.

(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. Although this multilayer printed wiring board is suitable for ultra-high density, it is difficult to form an organic insulating layer capable of firmly adhering the plating film, so that 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 plated coating 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 electric 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 based on a urethane (meth) acrylate of a phenol aralkyl resin represented by Formula 1 which is excellent in both heat resistance and flexibility. By constructing the composition, further containing a fine particle filler that can be dissolved and removed by chemical conversion treatment, the surface of the insulating layer is subjected to chemical conversion treatment to dissolve and remove the fine particle filler, and by roughening the surface of the insulating layer,
We have succeeded in remarkably improving the adhesion strength between the insulating layer and the plating film formed thereon, and have solved the above problems. That is, the present invention comprises (a) at least one compound represented by Formula 1 (n is 0 or more), and has at least one hydroxyl group for each of at least two hydroxyl groups ( (Meth) acrylate compound corresponds, the polyisocyanate compound having at least two isocyanate groups is interposed between the hydroxyl groups of both compounds, and the hydroxyl groups of both compounds react with the isocyanate groups of the polyisocyanate compound. A photopolymerizable compound, (b) a polymerizable compound having at least two terminal ethylene groups, (c) a photopolymerization initiator generating radicals by actinic rays, (d) a fine particle filler, (e) The present invention relates to a photosensitive resin composition containing a fine particle filler capable of being dissolved and removed by a chemical conversion treatment.

The photosensitive resin composition of the present invention comprises at least one compound represented by Formula 1 (n is 0 or more) as an essential component, and at least one compound for each of at least two or more hydroxyl groups. Corresponding to a (meth) acrylate compound having a hydroxyl group, a polyisocyanate compound having at least two isocyanate groups is present between the hydroxyl groups of both compounds, and the hydroxyl groups of both compounds and the isocyanate group of the polyisocyanate compound are It contains a photopolymerizable compound formed by reaction. A photosensitive resin composition composed of a urethane (meth) acrylate of a diol and a ketone resin is used as a solder resist for the purpose of permanent protection of printed wiring circuits and prevention of solder bridges between circuits when soldering components. This is already known as can be seen in JP-A-57-78415. However,
The diols used in these conventional examples have an aliphatic hydrocarbon as a skeleton, and have a drawback of low heat resistance. The present invention is characterized in that the diol is a compound represented by Formula 1 (n is 0 or more). The compound represented by Formula 1 (n is 0 or more) is generally obtained by condensing phenol and aralkyl ether (αα'-dimethoxyparaxylene) by Friedel-Crafts reaction, and is commonly known as phenol aralkyl resin. It is said that. This phenol aralkyl resin has excellent heat resistance because the skeleton is formed by an aromatic ring,
Since the hydroxyl groups serving as crosslinking points at the time of the reaction are present in every other aromatic ring, the crosslinking density is low and the flexibility is high. When this is compared with a phenol novolac resin or a cresol novolac resin, the difference in flexibility is particularly apparent. Here, the number of n in the formula 1 is preferably 2 or more, and more preferably the number of n is 4
That is all. The reason is that when the number n is 1 or less, tack does not completely disappear during drying, and when image exposure is carried out by the contact method, the film adheres to the photomask film and a smooth surface is difficult to obtain, and the resistance to the developing solvent decreases. This is because the surface of the insulating layer is easily corroded. However, since this problem can be solved by appropriately selecting the exposure method and the development method, the number of n is not particularly limited.

The polyisocyanates containing at least two isocyanate groups, which can then be used for the preparation of the photopolymerizable compounds according to the invention, are known compounds.
Examples thereof include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, methylcyclohexane-2,4-diisocyanate and isophorone diisocyanate. It is also possible to use these polymers.

The (meth) acrylate having at least one hydroxyl group used in the present invention is a known compound. For example, 2-hydroxyethyl methacrylate,
2-hydroxyethyl acrylate, 3-butoxy-2
Examples include -hydroxypropyl acrylate and 2-hydroxypentyl methacrylate. Generally, an acrylate having a fast photocuring reaction rate is preferable.

Next, an example of the method for producing the photopolymerizable compound of the present invention will be briefly described. First, the compound represented by Formula 1 (n is 0 or more)
At least one of, at a temperature of 50 ° C to 150 ° C,
The polyisocyanate having at least two isocyanate groups is reacted for 1 to 5 hours. At this time, the equivalent relationship between the hydroxyl group and the isocyanate group is that the isocyanate group is in excess with respect to the hydroxyl group. Next, the isocyanate group of this reaction product is reacted with a (meth) acrylate having at least one hydroxyl group. Reaction temperature is 50
The reaction is carried out at ℃ to 150 ℃ for 1 to 5 hours. At this time, the isocyanate group and the hydroxyl group are blended so that the equivalent relationship is almost equivalent. During the production of this photopolymerizable compound,
Solvents such as methyl ethyl ketone, toluene and methyl isobutyl ketone can be used.

Thus, the photopolymerizable compound which is an essential component of the photosensitive resin composition of the present invention (hereinafter referred to as the essential component (a))
To get

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 diacrylate, 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 coating 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,
Examples thereof include benzoin ethyl ether, 2,4-dialkylthioxanthone, and 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropanone. Furthermore, the photopolymerization initiator may be combined with a sensitizer having a different absorption wavelength of actinic rays to improve the polymerization initiation efficiency and further increase the sensitivity. Examples thereof include a combination of benzophenone and triethanolamine, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropanone and thioxanthone, and a combination of benzyldialkylketal and Michler's ketone. The amount of the initiator of the essential component (c) is 0.1 to 20 parts by weight, preferably 1 to 15 parts by weight, relative to 100 parts by weight of the photopolymerizable compound of the essential component (a).
Parts by weight.

The photosensitive resin composition of the present invention contains a fine particle filler (hereinafter referred to as an essential component (d)) as an essential component. Examples of the fine particle filler include silica, alumina, talc,
Examples thereof include antimony trioxide, antimony pentoxide, aluminum hydroxide, calcium carbonate and the like. The particle size of the fine particle filler is preferably 0.01 to 15 μm, more preferably 0.01 to 2.5 μm from the viewpoint of resolution, adhesion of the cured film, and the like. The amount of the fine particle filler of the essential component (d) 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 contains, as an essential component, a fine particle filler which can be dissolved and removed by chemical conversion treatment (hereinafter referred to as an essential component (e)). Fine particle fillers that can be dissolved and removed by chemical conversion treatment include inorganic fine particles such as silica and calcium carbonate, and heat resistant resin fine particles. But,
Here, it is desirable to use heat-resistant resin fine particles that have been previously cured. The reason why it is preferable to use the pre-cured heat-resistant resin fine particles is that when the pre-cured heat-resistant resin fine particles are used, they are dissolved in the resin liquid when dispersed in the photosensitive resin composition. This is because it becomes impossible to selectively dissolve and remove it by the chemical conversion treatment. If heat-resistant resin fine particles that have been previously cured are used,
Even when dispersed in the photosensitive resin composition, it does not dissolve in the resin liquid, 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. Further, as the specific chemical liquid used for the chemical conversion treatment, for example, an oxidizing agent such as chromic acid, chromate salt, permanganate salt 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 non-uniform, which makes it impossible to form a plated film with high reliability. The amount of the fine particle filler which can be dissolved and removed by the chemical conversion treatment of the essential component (e) 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 alicyclic 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 and cyclohexanone.

(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. In addition to having the excellent characteristics that the crosslink density is low and the flexibility is high because the groups are present every other aromatic ring, the (meth) acryloyl group that connects the skeletons of this photopolymerizable compound Is bonded to the hydroxyl group of the skeleton through an isocyanate group by a so-called urethane bond, and therefore exhibits an excellent effect on thermal shock resistance and the like.
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 component of the photosensitive resin composition for forming a protective film used in the production of general printed wiring boards. Differences in sex become apparent.

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

Further, since the photosensitive resin composition contains a fine particle filler that can be dissolved and removed by chemical conversion treatment, by applying chemical conversion treatment to the cured film of the photosensitive resin composition, minute irregularities are formed on the surface of the cured film. . 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 unevenness acts as an anchor, 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 which constitutes the main part of the photosensitive resin composition of the present invention is particularly 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 becomes higher 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.

Reference example Tolylene diisocyanate (made by Nippon Polyurethane, brand name: T
DI-80) 348 parts, dibutyltin dilaurate 1.0 part, hydroquinone 1.0 part, and toluene 350 parts were added and stirred, and then the temperature was raised to 60 ° C. to obtain a uniform solution.

Separately, 400 parts of a phenol aralkyl resin represented by Formula 1 (manufactured by Mitsui Toatsu Chemicals, Inc., trade name: Zyloc resin 225L, weight average molecular weight 1950, hydroxyl group equivalent 180) and 400 parts of toluene are mixed to prepare a uniform solution.

Next, the phenol aralkyl resin solution was uniformly added dropwise to the tolylene diisocyanate solution over 2 to 3 hours, and then kept at 60 ° C. for 3 hours. The reaction product of this reaction is shown in Formula 2.

Formula 2 Next, 2-hydroxyethyl acrylate (manufactured by Kyoeisha Oil and Fat Chemical Co., Ltd., trade name: light ester) was added to this reaction solution.
HOA) (232 parts) was added dropwise over 15 hours, and the mixture was kept warm for 5 hours, and then 10 parts of methanol was added to obtain a photopolymerizable compound. The photopolymerizable compound thus obtained is shown in Formula 3.

Formula 3 Example 1) 100 parts (in terms of solid content) of urethane acrylate of phenol aralkyl resin synthesized in Reference Example (shown in Formula 3), 15 parts of diallyl terephthalate, 2-methyl-1
-[4- (Methylthio) phenyl] -2-morpholinopropanone-1 (Ciba Geigy, trade name: Irgacure 907), 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 (Toray, trade name: Trepearl EP-
B, average particle size 0.5 μm) 25 parts by weight, and then add butyl cellosolve while adding a viscosity of 25 with a homodisper stirrer.
The solution was adjusted to 0 cps and then kneaded with a three-roll to prepare a solution of the photosensitive resin composition.

2) Next, a solution of the photosensitive resin composition is applied on a printed wiring board obtained by photoetching the surface of the copper-clad laminate by a conventional method using a knife coater, and then in a horizontal state.
After leaving it for 20 minutes, dry it by touching it at 70 ℃ and thickness is about 50μm.
To form a photosensitive resin layer.

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-treating at 2 ° C. for 2 hours, an interlayer insulating film having via holes corresponding to a photomask film and having excellent dimensional accuracy was obtained.

4) Next, apply this interlayer insulating film at a temperature of 70 ° C and a concentration of 500g /
It is roughened with chromic acid for 15 minutes, immersed in a neutralizing solution (manufactured by Shipley, trade name: PM950) and washed with water. Since this coating contains silica fine particles unnecessary for 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) Next, as a pre-treatment for chemical plating, a palladium catalyst (trade name: Cataposit 44, manufactured by Shipley Co., Ltd.) is applied to activate the surface, and the surface is immersed in a chemical copper plating solution of the following composition for 15 minutes, and then electroplated of the following composition. When 20 μm of copper was deposited in the via hole with the copper plating solution, the peel strength in the normal state was 2.15 kg / cm. Also, MIL-STD-202 Me
In the thermal shock test according to thod 107Condition B, 50
It was clarified that no disconnection occurred even after 0 cycles and long-term reliability was excellent. Further, the diallyl terephthalate contained in the resin solution increases the crosslink density during curing, so the cured coating has excellent heat resistance and was subjected to a solder heat resistance test at 260 ° C for 30 seconds, but peeling of the insulating layer coating and discoloration were confirmed. There wasn't.

Chemical copper plating solution composition Shipley 328A 12.5% Shipley company 328L 12.5% Shipley company 328C 1.5% Pure water 73.5% Temperature 25 ℃ Electrolytic copper plating solution composition CuSO ₄・ 5H ₂ O 150g / H ₂ SO ₄ 40g / 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. In particular, it has excellent thermal shock resistance, and since it contains silica fine particles unnecessary for chromic acid and epoxy resin fine particles soluble in chromic acid, the roughened surface shape becomes extremely complicated and a conductor is formed on the insulating layer. In this case, high adhesion can be obtained, and since the inorganic silica fine particles are included, the insulating film has a high hot altitude and thermal expansion is suppressed, so that the thermal shock resistance is particularly excellent.

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

Further, the protective film obtained by using the photosensitive resin composition of the present invention has excellent adhesion to the underlying conductor and can withstand a high temperature alkaline aqueous solution, so that permanent protection of plating resist, solder mask, etc. It can be used as a coating and is extremely useful industrially.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C08G 18/67 NFA G03F 7/027 513 H01L 21/027

Claims (1)

[Claims] 1. A photosensitive resin composition comprising the following (a) to (e). (A) A (meth) acrylate compound having at least one hydroxyl group corresponds to at least one of the compounds represented by Formula 1 (n is 0 or more) and to at least two hydroxyl groups. A polyisocyanate compound having at least two isocyanate groups is present between the hydroxyl groups of both compounds, and the photopolymerizable compound is formed by reacting the hydroxyl groups of both compounds with the isocyanate groups of the polyisocyanate 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) Fine particle filler. (E) A fine particle filler that can be dissolved and removed by chemical conversion treatment.