JP5732729B2 - Resin composition for wiring board and resin sheet for wiring board - Google Patents

Description

  The present invention relates to a resin composition for wiring boards and a resin sheet for wiring boards.

In recent years, with the demand for higher functionality, lighter weight, smaller size, and thinner electronic devices, high-density integration and high-density mounting of electronic components are progressing. Circuit wiring of printed wiring boards used in these electronic devices tends to have a higher density, and a multilayer wiring structure is adopted.

  Until now, the semi-additive method has been used as a method generally applied to the production of multilayer printed wiring boards. In this method, the resin surface is desmeared to roughen the surface, an electroless copper plating layer using a palladium catalyst is formed on the surface, a photosensitive resist is formed on the copper plating layer, and exposure / development is performed. After patterning through a process such as the above, a circuit pattern is formed by electrolytic copper plating, finally the resist is peeled off, and the electroless copper plating layer is removed by flash etching to form fine wiring. (For example, refer to Patent Document 1). When fine wiring is formed by this method, there are problems such as exposure / development accuracy of resist and abnormal plating deposition due to palladium catalyst residue between wiring, and the circuit width / inter-circuit width (L / S) is 10 μm / 10 μm or less. It was difficult to form fine wiring.

Therefore, in order to form a fine wiring with L / S of 10 μm / 10 μm or less, a method for forming a circuit by directly digging a groove on the surface of the insulating layer has been devised as a new process. This is because the three surfaces of the conductor layer are in close contact with the insulating layer, and good adhesion can be obtained. For example, a groove is formed in the insulating layer by scribing, plasma, laser, etc., the surface of the resin is desmeared to roughen the surface, and an electroless copper plating layer using a palladium catalyst is formed on the surface. There is a method in which a conductor is formed and finally a conductor plating other than the groove portion is removed by etching to form a circuit (for example, described in Patent Documents 2 and 3). However, when the unevenness of the groove side wall surface of the insulating layer becomes large, there is a new problem that accuracy in forming the groove is lowered and it becomes difficult to form fine wiring with L / S of 10 μm / 10 μm or less.

JP-A-8-64930 Japanese Patent Laid-Open No. 10-4253 JP 2006-41029 A

The present invention, when used for an insulating layer of a printed wiring board, has excellent groove processability for forming fine wiring with a circuit width / inter-circuit width (L / S) of 10 μm / 10 μm or less by laser processing. Provided are a resin composition and a resin sheet that form an insulating layer having high adhesion between the insulating layer and the formed conductor circuit.

Such an object is achieved by the following items [1] to [6] of the present invention.
[1] A resin composition comprising an inorganic filler and a thermosetting resin, wherein the inorganic filler has a coarse particle exceeding 2 μm in an amount of 500 ppm or less, and the thermosetting resin is a naphthalene-modified cresol novolac epoxy. A combination of resin and novolac cyanate resin,
Characterized in that it comprises a naphthalene dimethylene type epoxy resin, and one or more resins selected from among benzocyclobutene resin, wiring boards used for the insulating layer of the circuit formed by digging directly grooves by laser processing on a surface Resin composition.
[2] The resin composition for a wiring board according to [1], wherein the inorganic filler has an average particle size of 0.05 μm or more and 1.0 μm or less.
[3] The resin composition for a wiring board according to [1] or [2], wherein the content of the inorganic filler is 10 to 80% by weight in the resin composition.
[4] The resin composition for a wiring board according to any one of [1] to [3], wherein the inorganic filler is spherical silica.
[5] The resin composition for a wiring board according to any one of [1] to [4], wherein the resin composition contains 5 to 12% by weight of a thermoplastic resin, and the thermoplastic resin is a phenoxy resin. .
[6] A circuit layer is formed by directly forming a groove on the surface by laser processing, wherein a resin layer made of the resin composition for a wiring board according to any one of [1] to [5] is formed on a substrate. Resin sheet for wiring boards used for insulating layers .

  When the resin composition for a wiring board according to the present invention and the resin sheet for a wiring board using the resin composition are used for an insulating layer of a printed wiring board, the circuit width / inter-circuit width (L / S) can form fine wiring of 10 μm / 10 μm or less, and adhesion between the formed insulating layer and the conductor circuit is high.

It is a resin sheet for wiring boards of the present invention. It is the schematic diagram shown about an example of the method of manufacturing the printed wiring board containing the insulating layer and conductor layer which consist of a resin composition for wiring boards of this invention. In Example 2, it is a cross-sectional shape photograph in the stage which formed the groove | channel in the insulating layer with the laser, and formed the conductor by electroless plating and electrolytic plating. In comparative example 1, it is a cross-sectional photograph at the stage where a groove was formed in an insulating layer by laser and a conductor was formed by electroless plating / electrolytic plating.

  Below, the resin composition for wiring boards of this invention and the resin sheet for wiring boards using the said resin composition are demonstrated in detail.

The resin composition for a wiring board of the present invention contains an inorganic filler and a thermosetting resin, and the coarse particles with an inorganic filler exceeding 2 μm are 500 ppm or less.
When the resin composition for a wiring board of the present invention contains an inorganic filler, when used for an insulating layer of a wiring board such as a multilayer printed wiring board or a metal core wiring board, it becomes low thermal expansion, high elasticity, low water absorption, Mounting reliability and warpage are improved. And about the inorganic filler which fulfill | performs such a function, since the coarse particle exceeding 2 micrometers was 500 ppm or less, the insulating layer which consists of the said resin composition is a circuit width / inter-circuit width (L / S) by laser processing. ) Is excellent in processability when processing a groove for forming a fine wiring of 10 μm / 10 μm or less, and it is possible to suppress the unevenness of the side wall surface inside the groove from becoming too large. On the other hand, since the coarse particle content that adversely affects the unevenness while including the inorganic filler is specified, the unevenness of the side wall surface inside the groove after laser processing becomes appropriate, and the conductor circuit formed with the insulating layer An insulating layer having high adhesion can be formed.
Further, the unevenness on the side wall surface of the insulating layer inside the groove in contact with the conductor circuit is reflected in the unevenness on the surface of the conductor circuit inside the groove. According to the present invention, the surface unevenness of the conductor circuit formed in the groove is reduced, transmission loss due to the skin effect can be reduced in a high frequency region exceeding 1 GHz, and fine wiring for high frequency can be formed. A high-frequency signal causes signal propagation on the surface of the conductor circuit. However, if the surface irregularity of the conductor circuit is too large, the transmission distance increases, so that transmission becomes slow or loss during propagation increases.
From the above, when the resin composition for a wiring board according to the present invention is used for an insulating layer, the surface irregularity of the conductor circuit is reduced while ensuring the adhesion between the conductor circuit and the insulating layer in the fine wiring, and the high frequency exceeding 1 GHz. In the frequency domain, transmission loss due to the skin effect can be reduced.

First, the inorganic filler used for the resin composition of the present invention will be described.
The inorganic filler has 500 ppm or less of coarse particles exceeding 2 μm. As a result, when used for an insulating layer of a wiring board, the groove width for forming fine wiring with a circuit width / inter-circuit width (L / S) of 10 μm / 10 μm or less by laser processing, Excellent workability and excellent adhesion between the formed insulating layer and the formed conductor circuit. The inorganic filler preferably further has a coarse particle exceeding 2 μm in an amount of 300 ppm or less, and particularly a coarse particle exceeding 2 μm in an amount of 5 ppm or less.
In addition, the method of obtaining the inorganic filler whose coarse particle over 2 micrometers is 500 ppm or less is not specifically limited. For example, as a method of removing coarse particles exceeding 2 μm, in a slurry state in an organic solvent and / or water, coarse particles are removed several times with a pore size filter having an average particle size of 10 times or more, and then a pore size of 2 μm. It can be obtained by repeatedly removing coarse particles exceeding 2 μm with a filter.

  The coarse particle size and content of the inorganic filler can be measured with a particle image analyzer (FPIA-3000S manufactured by Sysmex Corporation). The inorganic filler can be dispersed by ultrasonic waves in water or an organic solvent, and the number of inorganic fillers exceeding 2 μm can be calculated and measured from the obtained image. Specifically, the content is defined by the number of particles exceeding 2 μm in the equivalent circle diameter of the inorganic filler and the total number of analyzed particles.

  Among these, the maximum particle size of the inorganic filler is preferably 2.0 μm or less. Thereby, it becomes easy to realize the surface roughness of the specified resin layer, and it is possible to form fine wiring with high insulation reliability and excellent signal response. Although not particularly limited, the maximum particle size of the inorganic filler is more preferably 1.8 μm or less, and particularly preferably 1.5 μm or less. Thereby, the effect | action which improves insulation reliability, signal responsiveness, the plating property in a via | veer and a groove | channel, and interlayer connection reliability can be expressed effectively.

  The average particle size of the inorganic filler is preferably 0.05 μm or more and 1.0 μm or less. Thereby, the insulation reliability of a multilayer printed wiring board becomes high, and it becomes easy to implement | achieve fine wiring formation excellent in signal responsiveness. More preferably, the average particle size of the inorganic filler is 0.05 μm or more and 0.60 μm or less, and particularly preferably 0.05 μm or more and 0.40 μm or less. Thereby, the effect | action which improves insulation reliability, signal responsiveness, the plating property in a via | veer and a groove | channel, and interlayer connection reliability can be expressed effectively.

  The average particle diameter of the inorganic filler can be measured by a laser diffraction scattering method. The inorganic filler is dispersed in water by ultrasonic waves, and the particle size distribution of the inorganic filler is created on a volume basis by a laser diffraction type particle size distribution measuring device (manufactured by HORIBA, LA-500). It can be measured by doing. Specifically, the average particle diameter of the inorganic filler is defined by D50.

  If the amount of coarse particles exceeding 2 μm of the inorganic filler exceeds the above upper limit, the inorganic filler inhibits laser processing, resulting in a location where the insulating layer cannot form a groove, the via shape becomes distorted, or the resin There is a possibility that cracks may occur, and there is a risk that insulation reliability and plating performance due to dropping of coarse fillers may be reduced. Furthermore, since the time for forming the groove with the laser beam becomes longer, there is a possibility that the workability is lowered. Moreover, the surface unevenness | corrugation of the conductor layer after plating becomes large with the inorganic filler which remained on the groove | channel side wall surface after laser processing. As a result, the accuracy of the wiring deteriorates, and the insulation reliability may be impaired in the high-density printed wiring board. Furthermore, in a high frequency region exceeding 1 GHz, signal responsiveness may be impaired due to the skin effect. Even if the average particle size of the inorganic filler exceeds the upper limit, there is a similar possibility.

  In addition, when the average particle size of the inorganic filler is less than the lower limit, the physical properties of the thermal expansion coefficient and elastic modulus of the resin layer formed using the resin composition are reduced, and mounting when mounting a semiconductor element There is a possibility of impairing the reliability, and the dispersibility of the inorganic filler in the resin composition and the occurrence of agglomeration occur, making it difficult to form a resin film due to the decrease in flexibility in the B-stage state of the resin composition There is a risk.

  Examples of the inorganic filler include, but are not limited to, silicates such as talc, fired clay, unfired clay, mica, and glass, oxides such as titanium oxide, alumina, silica, and fused silica, calcium carbonate, and carbonic acid. Carbonates such as magnesium and hydrotalcite, hydroxides such as aluminum hydroxide, magnesium hydroxide and calcium hydroxide, sulfates or sulfites such as barium sulfate, calcium sulfate and calcium sulfite, zinc borate and barium metaborate And borate salts such as aluminum borate, calcium borate and sodium borate, nitrides such as aluminum nitride, boron nitride, silicon nitride and carbon nitride, titanates such as strontium titanate and barium titanate Can do. As the inorganic filler, one of these can be used alone, or two or more can be used in combination. Among these, silica is preferable and fused silica is more preferable in terms of excellent low thermal expansion, flame retardancy, and elastic modulus. Among these, the shape is preferably spherical. In addition, using nano silica with an average particle size of 200 nm or less in combination with other inorganic fillers is excellent in workability when processing grooves for forming fine wiring by laser processing, and the side wall surface inside the grooves is fine. It is preferable because it can be roughened. When nano silica having an average particle size of 200 nm or less is used in combination with another inorganic filler, the nano silica having an average particle size of 200 nm or less is preferably 1.0 to 25% by weight in the inorganic filler.

  The content of the inorganic filler in the resin composition of the present invention is 10 to 80% by weight, more preferably 20 to 70% by weight, particularly 30 to 60% by weight in the resin composition, so that the insulation reliability is high. It is preferable from the point that fine wiring with excellent signal response can be formed.

  On the other hand, examples of the thermosetting resin used in the resin composition of the present invention include novolak type phenol resins such as phenol novolak resin, cresol novolak resin, bisphenol A novolak resin, unmodified resole phenol resin, tung oil, and linseed oil. Resol type phenol resin such as oil modified resol phenol resin modified with walnut oil, phenol resin such as biphenyl aralkyl type phenol resin, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin Bisphenol Z type epoxy resin, bisphenol P type epoxy resin, bisphenol type epoxy resin such as bisphenol M type epoxy resin, phenol novolac type epoxy resin, cresol novo Epoxy resin, novolac epoxy resin, biphenyl epoxy resin, biphenyl aralkyl epoxy resin, arylalkylene epoxy resin, naphthalene epoxy resin, anthracene epoxy resin, phenoxy epoxy resin, dicyclopentadiene epoxy resin, norbornene type Epoxy resin, adamantane type epoxy resin, epoxy resin such as fluorene type epoxy resin, resin having triazine ring such as urea (urea) resin, melamine resin, unsaturated polyester resin, bismaleimide resin, polyimide resin, polyamideimide resin, polyurethane Examples thereof include resins, diallyl phthalate resins, silicone resins, resins having a benzoxazine ring, triazine resins, benzocyclobutene resins, and cyanate resins. Among these, the inclusion of one or more kinds of resins selected from epoxy resins, phenol resins, cyanate resins and benzocyclobutene resins forms fine wiring with high insulation reliability and excellent signal response. It is preferable to contain an epoxy resin and a phenol resin and / or a cyanate resin, and it is particularly preferable to contain a cyanate resin. Thereby, the thermal expansion coefficient of the resin layer can be reduced. Further, when a cyanate resin is included, the resin layer is excellent in electrical characteristics (low dielectric constant, low dielectric loss tangent), mechanical strength, laser workability, particularly excimer laser and YAG laser workability.

  Specific examples of the cyanate resin include novolak type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin, tetramethylbisphenol F type cyanate resin and the like, bisphenol type cyanate resins, naphthol aralkyl type cyanate resins, and biphenyl aralkyl type cyanate. Resin, dicyclopentadiene-type cyanate resin, and the like. Among these, novolac type cyanate resin is preferable. The novolac-type cyanate resin can reduce the thermal expansion coefficient of the resin layer, and is excellent in mechanical and mechanical strength and electrical characteristics (low dielectric constant, low dielectric loss tangent) of the resin layer. Naphthol aralkyl-type cyanate resins and biphenyl aralkyl-type cyanate resins can also be preferably used because they are excellent in low linear expansion, low water absorption, and mechanical strength.

Although the weight average molecular weight of the cyanate resin is not particularly limited, the weight average molecular weight is preferably 5.0 × 10 ^{2 to} 4.5 × 10 ³ , and particularly preferably 6.0 × 10 ^{2 to} 3.0 × 10 ³ . When the weight average molecular weight is less than the lower limit, the mechanical strength of the insulating layer of the multilayer printed wiring board may decrease, and when forming the insulating layer during the production of the multilayer printed wiring board, tackiness occurs, A part of the insulating layer may be missing. Further, when the weight average molecular weight exceeds the above-described actual value, the curing reaction is accelerated, and there are cases where an insulating layer molding failure occurs during the production of a multilayer printed wiring board, and the insulating interlayer peel strength decreases. In addition, weight average molecular weights, such as cyanate resin, can be measured by GPC (gel permeation chromatography, standard substance: polystyrene conversion), for example.

Further, although not particularly limited, cyanate resins including derivatives thereof can be used alone, or two or more having different weight average molecular weights can be used in combination, or one or two or more thereof. A prepolymer can also be used in combination.
Although content of cyanate resin is not specifically limited, 5 to 50 weight% of the whole resin composition is preferable, and 10 to 30 weight% is especially preferable. If the content is less than the lower limit, the reactivity of the thermosetting resin composition and the low thermal expansion may decrease, or the heat resistance of the resulting product may decrease. May decrease.

  When a cyanate resin (particularly a novolac-type cyanate resin) is used as the thermosetting resin, it is preferable to use an epoxy resin (substantially free of halogen atoms) in combination.

Although it does not specifically limit as an epoxy resin, For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol Z type epoxy resin, bisphenol P type epoxy resin, bisphenol M type epoxy resin Bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac epoxy resin, etc. novolac type epoxy resin, biphenyl type epoxy resin, xylylene type epoxy resin, biphenyl aralkyl type epoxy resin, etc. Resin, anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type epoxy resin, Adamantane type epoxy resins and fluorene type epoxy resins and the like.
One of these can be used alone, two or more having different weight average molecular weights can be used in combination, or two or more of the above epoxy resins can be used in combination with their prepolymers. .

  Among these epoxy resins, aryl alkylene type epoxy resins are particularly preferable. Thereby, moisture absorption solder heat resistance and a flame retardance can be improved. The aryl alkylene type epoxy resin refers to an epoxy resin having one or more aryl alkylene groups in a repeating unit. For example, xylylene type epoxy resin, anthracene type epoxy resin, biphenyl dimethylene type epoxy resin, naphthalene dimethylene type epoxy resin, naphthalene modified cresol novolac epoxy resin and the like can be mentioned. Among these, biphenyl dimethylene type epoxy resins, naphthalene-modified cresol novolac epoxy resins, anthracene type epoxy resins, and naphthalene dimethylene type epoxy resins are preferable. A naphthol aralkyl type epoxy resin and a dicyclopentadiene type epoxy resin can also be preferably used because of low linear expansion, low water absorption, and excellent mechanical strength.

  Although content of an epoxy resin is not specifically limited, 1 to 55 weight% of the whole resin composition is preferable, and 5 to 40 weight% is especially preferable. If the content is less than the lower limit, the reactivity of the cyanate resin may decrease, or the moisture resistance of the resulting product may decrease. If the content exceeds the upper limit, the low thermal expansion and heat resistance will decrease. There is a case.

The weight average molecular weight of the epoxy resin is not particularly limited, but the weight average molecular weight is preferably 5.0 × 10 ^{2 to} 2.0 × 10 ⁴ , and particularly preferably 8.0 × 10 ^{2 to} 1.5 × 10 ⁴ . If the weight average molecular weight is less than the lower limit, when forming an insulating layer during the production of a multilayer printed wiring board, tackiness may occur, and a portion of the insulating layer may be missing, and if the upper limit is exceeded, the multilayer printed wiring The solder heat resistance of the board may decrease. By setting the weight average molecular weight within the above range, it is possible to achieve an excellent balance of these characteristics. The weight average molecular weight of the epoxy resin can be measured, for example, by GPC (gel permeation chromatography, standard substance: converted to polystyrene).

The said thermosetting resin can be used 1 type or in combination of 2 or more types. Usually, it is used as a thermosetting resin in combination with a curing agent.
The content of the thermosetting resin is not particularly limited, but is preferably 20 to 90% by weight, more preferably 30 to 80% by weight, and particularly preferably 40 to 70% by weight in the resin composition for forming a resin layer. If the content is less than the lower limit, it may be difficult to form the resin layer, and if the content exceeds the upper limit, the strength of the resin layer may be reduced.

  In the resin composition, as long as the effects of the present invention are not impaired, a film-forming resin, a curing accelerator, a coupling agent, a pigment, a dye, an antifoaming agent, a leveling agent, an ultraviolet absorber, and foaming are provided as necessary. You may add additives other than the said components, such as an agent, antioxidant, a flame retardant, and an ion-trapping agent.

The resin composition preferably contains a film-forming resin from the viewpoint of improving the uniformity of the coating film surface and uniformly roughening the surface during the desmear treatment. As the film-forming resin, a thermoplastic resin such as a phenoxy resin is preferably used.
In the case of using a film-forming resin in the resin composition of the present invention, the content of the resin composition is 1 to 20% by weight, more preferably 5 to 15% by weight, from the viewpoint of low thermal expansion and heat resistance. preferable.

In addition, the resin composition improves the uniform dispersibility of the inorganic filler, and when the groove for forming fine wiring is processed by laser processing, the side wall surface inside the groove can be uniformly roughened. It is preferable that a coupling agent is included. Examples of the coupling agent include a silane coupling agent, a titanate coupling agent, and an aluminum coupling agent. Examples of the silane coupling agent include N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3- (2-aminoethyl) aminopropyltrimethoxysilane. 3- (2-aminoethyl) aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-anilinopropyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -3-aminopropyl Aminosilane compounds such as trimethoxysilane and N-β- (N-vinylbenzylaminoethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane and 2 -(3,4-epoxy Cyclohexyl) epoxysilane compounds such as ethyltrimethoxysilane, and others include 3-mercatopropyltrimethoxysilane, 3-mercatopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, and Examples include 3-methacryloxypropyltrimethoxysilane. From the viewpoint of close contact with the thermosetting resin, epoxy silane, amino silane and the like are preferably used.
When the coupling agent is used in the resin composition of the present invention, the content of the resin composition is 0.1 to 5% by weight, more preferably 0.25 to 2.5% by weight, and It is preferable from the viewpoint of heat resistance.

Next, the resin sheet for wiring boards of the present invention will be described.
The resin sheet for wiring boards according to the present invention can be obtained by forming a resin layer made of the resin composition for wiring boards according to the present invention on a substrate.

  FIG. 1 is a schematic view of a resin sheet using the resin composition of the present invention.

  Although the said base material 1 is not specifically limited, A polymer film or metal foil can be used. Although it does not specifically limit as a polymer film, For example, the thermoplastic resin film which has heat resistance, such as polyester resins, such as a polyethylene terephthalate and a polybutylene terephthalate, a fluorine resin, and a polyimide resin can be used. The metal foil is not particularly limited. For example, copper and / or a copper-based alloy, aluminum and / or an aluminum-based alloy, iron and / or an iron-based alloy, silver and / or a silver-based alloy, gold and a gold-based alloy, Metal foils such as zinc and zinc alloys, nickel and nickel alloys, tin and tin alloys can be used.

  Although the thickness of the said resin layer 2 is not specifically limited, 1-60 micrometers is preferable and 5-40 micrometers is especially preferable. The thickness of the resin layer is preferably equal to or greater than the lower limit for improving insulation reliability, and is preferably equal to or less than the upper limit for achieving thinning of the multilayer printed wiring board. Thereby, when manufacturing a printed wiring board, while being able to shape | mold the insulating layer with which the unevenness | corrugation of the conductor layer of the inner layer circuit board was filled, the thickness of a suitable insulating layer can be ensured.

Although it does not specifically limit as thickness of the said polymer film or metal foil, The handleability at the time of manufacturing the resin sheet 30 is favorable when the thing of 10-70 micrometers is used.
In manufacturing the resin sheet 30 of the present invention, it is preferable that the unevenness of the base material surface in contact with the insulating layer is as small as possible. Thereby, uniform roughening can be formed on the surface of the insulating layer, and fine wiring processing is facilitated.

  Although the manufacturing method of the resin sheet 30 of the present invention is not particularly limited, for example, a resin varnish is prepared by dissolving and dispersing the resin composition in a solvent or the like, and the resin varnish is formed on the substrate using various coater apparatuses. The method of drying this after coating, the method of drying this after spray-coating a resin varnish on a base material using a spray apparatus, etc. are mentioned. Among these, a method in which a resin varnish is coated on a substrate using various coaters such as a comma coater and a die coater and then dried is preferable. Thereby, the resin sheet which does not have a void and has the thickness of the uniform resin layer can be manufactured efficiently.

  The solvent used in the resin varnish desirably exhibits good solubility in the resin component in the resin composition, but a poor solvent may be used within a range that does not adversely affect the resin varnish. Examples of the solvent exhibiting good solubility include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, cellosolve and carbitol. Although it does not specifically limit as solid content in the said resin varnish, 30 to 80 weight% is preferable and especially 40 to 70 weight% is preferable.

Next, the manufacturing method of the printed wiring board using the resin sheet of this invention is demonstrated.
About the manufacturing method of a printed wiring board, it does not specifically limit except giving a groove process and producing a conductor circuit.

  An example of a method for manufacturing a printed wiring board will be described with reference to FIG.

  After laminating the resin sheet 30 of the present invention on the inner circuit board 50 in which the conductor layer 4 is disposed on the glass epoxy base material 5 (FIG. 2A), the base material is peeled to form the insulating layer 20 (FIG. 2 ( b)). In addition, when a base material is metal foil, you may implement a heat processing suitably before an etching removal and subsequent groove processing.

Next, the laser beam 6 is irradiated (FIG. 2C), and the groove 7 is formed on the surface of the insulating layer 20 (FIG. 2D).
The laser beam 6 is preferably an excimer laser or a YAG laser. By using these lasers, fine wiring can be formed with high accuracy and shape. Although not particularly limited, the laser wavelength of the excimer laser is more preferably 193 nm, 308 nm, and 248 nm, and particularly preferably 193 nm and 248 nm. Thereby, the effect | action which can form fine wiring with sufficient precision and shape can be expressed effectively. The wavelength of the YAG laser is preferably 355 nm. At other wavelengths, the resin composition constituting the insulating layer 20 may not absorb the laser light 6 and fine wiring may not be formed. In addition, after forming the groove | channel 7, you may add a desmear process suitably for adhesiveness improvement.

  Next, a step of forming the electroless plating layer 8 on the surface of the insulating layer 20 by electroless plating (FIG. 2E), a step of forming the electroplating layer 9 (FIG. 2F), one of the conductors 10 The step of forming the conductor layer 11 only in the groove 4 portion of the resin layer 20 by removing the portion (FIG. 2G), another insulating layer 40 is formed on the insulating layer 20 and the conductor layer 11. A printed wiring board can be obtained by the process (FIG. 2 (h)). Furthermore, a multilayer printed wiring board can be manufactured by repeating FIG.2 (c) to FIG.2 (h).

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to this.

< Reference Example 1>
(1) Preparation of varnish 13.4 parts by weight of a polyfunctional epoxy resin (naphthalene-modified cresol novolac epoxy resin, manufactured by DIC, HP-5000) as a thermosetting resin, bifunctional epoxy resin (produced by Japan Epoxy Resin, Epicoat 828EL) ) 13.4 parts by weight, phenol resin (Maywa Kasei Co., Ltd., MEH7851-4L) 22.7 parts by weight, phenoxy resin as a thermoplastic resin (Japan Epoxy Resin, YX-8100BH30, solid content 30%) 8.8 40.8 parts by weight (solid content), 40.8 parts by weight of spherical silica (NSS-3N, average particle size 0.12 μm, manufactured by Tokuyama Co., Ltd.) having a coarse particle size exceeding 2 μm as an inorganic filler, and an imidazole compound (Shikoku Kasei Kogyo Co., Ltd.) Manufactured by Curazole 2E4MZ 0.3 parts by weight, silane coupling agent (momentive puff -Performance Materials Japan Inc., A-187) dissolved 0.6 parts by weight, the methyl ethyl ketone and dispersed. In addition, the ratio of the inorganic filler in the resin composition is about 41% by weight, and the coarse particles of the inorganic filler are dispersed in methyl ethyl ketone in advance, and a multilayer cartridge filter (Sumitomo 3M) with a 2 μm pore size filter. The particles having a maximum particle size of 2.0 μm were separated by filtration using a spherical silica having the above coarse particle amount and average particle size. The amount of coarse particles was confirmed using a particle image analyzer (FPIA-3000S manufactured by Sysmex Corporation).

(2) Production of Resin Sheet The resin varnish obtained above is applied to one side of a 37 μm thick PET (polyethylene terephthalate) film so that the thickness of the resin layer after drying using a comma coater device is 40 μm. This was coated and dried for 10 minutes with a drying device at 160 ° C. to prepare a resin sheet.

(3) Production of Evaluation Board (3) -1 Evaluation Board 1
This resin sheet is superposed on an inner layer circuit board on which a double-sided circuit of a glass epoxy base is formed, and this is subjected to vacuum heating and pressure molding at a temperature of 100 ° C. and a pressure of 1 MPa using a vacuum pressure laminator device, and PET After peeling off the substrate, the substrate was heated and cured at 180 ° C. for 45 minutes with a hot air drying device to obtain a substrate having an insulating layer.
In addition, the following were used as the inner layer circuit board.
Glass epoxy substrate: Sumitomo Bakelite Co., Ltd. ELC-4585GS-B, thickness 0.4 mm
Conductor layer: copper foil thickness 18 μm, L / S = 120/180 μm, clearance holes 1 mmφ, 3 mmφ, slit 2 mm

Next, a groove having a target width of 10 μm and a target depth of 15 μm was formed in the insulating layer with an excimer laser having a wavelength of 193 nm, and the resulting laminate was made into a swelling solution at 60 ° C. (Swelling Dip, manufactured by Atotech Japan Co., Ltd.). It was immersed for 10 minutes in securigant P500) and further immersed for 20 minutes in an aqueous potassium permanganate solution (manufactured by Atotech Japan Co., Ltd., Concentrate Compact CP) at 80 ° C., followed by neutralization and desmear treatment.

(3) -2 Evaluation board 2
Next, the insulating layer surface of the laminate is degreased, subjected to a catalyst application and activation process, and then an electroless copper plating layer of about 0.2 μm is formed. Electrolytic copper plating (Okuno) using the electroless copper plating layer as an electrode Pharmaceutical industry, Top Lucina α) was applied at 3 A / dm 2 for 30 minutes to form a conductor layer having a thickness of about 5 μm from the insulating layer surface.

(3) -3 Evaluation board 3
Finally, by conducting a quick etching process (SAC process manufactured by Ebara Densan Co., Ltd.), the conductor layer height was aligned with the surface of the insulating layer, and fine wiring processing of L / S = 10/10 was performed. Next, the insulating resin layer was completely cured at a temperature of 200 ° C. for 60 minutes. Finally, the same resin sheet is superposed on both sides, and this is subjected to vacuum heating and press molding at a temperature of 100 ° C. and a pressure of 1 MPa using a vacuum pressurizing laminator device, and then heated at 200 ° C. at 60 ° C. Heat curing was performed for a minute.

(3) -4 Semiconductor Device A semiconductor device was manufactured using the evaluation substrate 3 obtained above.
As a semiconductor element (TEG chip, size 15 mm × 15 mm, thickness 0.725 mm), solder bumps are formed of eutectic having a diameter of 120 μm, a pitch of 150 μm, and Sn / Pb composition, and a circuit protective film is a positive photosensitive resin (Sumitomo). What was formed by Bakelite CRC-8300) was used. In assembling the semiconductor device, first, a flux material was uniformly applied to the solder bumps by a transfer method, and then a semiconductor element was mounted on the evaluation substrate 3 by thermocompression bonding using a flip chip bonder device. Next, after solder bumps are melt-bonded in an IR reflow furnace, a liquid sealing resin (manufactured by Sumitomo Bakelite Co., Ltd., CRP-4152S) is filled between the evaluation substrate 3 and the semiconductor element, and the liquid sealing resin is cured. Thus, a semiconductor device was obtained. The liquid sealing resin was cured at a temperature of 150 ° C. for 120 minutes.

<Example 4, Reference Examples 2 and 3 >
In Example 4, Reference Examples 2 and 3, the resin sheet, evaluation substrates 1, 2 and 3, and a semiconductor device were obtained in the same manner as Reference Example 1 according to the formulation table in Table 1.

< Reference Example 5>
(1) Preparation of varnish A resin varnish was prepared in the same manner as in Reference Example 1 according to the formulation table in Table 1.
(2) Preparation of resin sheet Reference Example 1 except that after the varnish was prepared, instead of a PET (polyethylene terephthalate) film, an ultrathin copper foil (Mitsui Metal Mining Co., Ltd., Micro Thin MT-Ex, 3 μm) was used. Similarly, a resin sheet having an ultrathin copper foil was produced.

(3) Production of Evaluation Board (3) -1 Evaluation Board 1
The resin sheet having the ultrathin copper foil is placed on an inner circuit board on which a double-sided circuit of a glass epoxy base is formed, and this is vacuum-heated at a temperature of 100 ° C. and a pressure of 1 MPa using a vacuum pressure laminator device. It pressure-molded and heat-hardened at 180 degreeC for 45 minute (s) with the hot air dryer.
Next, the copper foil was removed by etching to obtain an evaluation substrate 1.

(3) -2 Evaluation board 2
The evaluation board | substrate 2 was obtained using the said evaluation board | substrate 1 similarly to the reference example 1. FIG.

(3) -3 Evaluation board 3
The evaluation board 3 was obtained using the evaluation board 2 in the same manner as in Reference Example 1.

(3) -4 Semiconductor device
Similar to Reference Example 1, the evaluation substrate 3 was used to obtain a semiconductor device.

<Example 6>
Except that a groove having a width of 10 μm and a depth of 15 μm was formed in the insulating layer by a YAG laser having a wavelength of 355 nm on the substrate having the insulating layer using the resin sheet obtained in Example 4, the same as in Example 1. Evaluation substrates 1, 2, and 3 and a semiconductor device were obtained.

<Examples 8, 10-15, and 17, Reference Examples 7, 9, and 16 >
In Examples 8, 10 to 15, and 17 and Reference Examples 7, 9, and 16, the resin sheet, evaluation substrates 1, 2, and 3, and a semiconductor device were obtained in the same manner as in Reference Example 1 according to the recipe of Table 1. It was.

<Comparative Example 1>
The same as in Reference Example 1 except that a general-purpose epoxy resin-based resin sheet (GX-13, manufactured by Ajinomoto Co., Inc., maximum inorganic filler particle size 2.5 μm, inorganic filler average particle size 0.5 μm) was used. Thus, an evaluation substrate and a semiconductor device were obtained. In the evaluation substrate 1, the conditions were 170 ° C. for 60 minutes, and for the evaluation substrate 3, the conditions were 180 ° C. for 60 minutes. The amount of coarse particles of the inorganic filler was confirmed by using a particle image analyzer (FPIA-3000S manufactured by Sysmex Corporation) after taking a resin from a resin sheet and dissolving it in a solvent. Met.

In Comparative Examples 2 and 3, a resin sheet, evaluation substrates 1, 2, and 3, and a semiconductor device were obtained in the same manner as in Reference Example 1 in accordance with the recipe of Table 1.

The evaluation shown below was performed using the resin sheet, the evaluation board | substrate 1, the evaluation board | substrate 2, and the evaluation board | substrate 3, and the semiconductor device which were obtained by the said Example, the reference example, and the comparative example. The obtained results are shown in Table 2.

(1) Arithmetic average roughness (Ra) of insulating layer surface after desmearing
The arithmetic average roughness (Ra) was measured using WYKO NT1100 manufactured by Veeco in accordance with JIS B0601. The evaluation substrate 1 was used as an evaluation sample.

(2) 10-point average roughness (Rz) of the conductor layer wall surface
From the cross section of the conductor wiring, 10-point average roughness (Rz) was calculated according to JIS B0601. The evaluation substrate 2 was used as an evaluation sample.

(3) Inter-line insulation reliability (HAST)
A line insulation reliability test was performed under the conditions of an applied voltage of 3.3 VDC, a temperature of 130 ° C., and a humidity of 85%. In addition, the evaluation board | substrate 3 was used for the evaluation sample.
When the insulation resistance value was less than 1 × 10 ⁸ Ω, it was judged as defective and the test was terminated.
Each code is as follows.
◎: Good 500 hours or more ○: Virtually no problem 200 hours or more and less than 500 hours ×: Unusable Less than 200 hours

(4) Thermal expansion coefficient (α1)
A test piece having a thickness of 40 μm and 5 mm × 20 mm was cut out, and the linear expansion coefficient in the plane direction (X direction) was measured using a TMA apparatus (manufactured by TA Instruments) at 5 ° C./min and 5 g. The average linear expansion coefficient from 25 ° C. to 120 ° C. was defined as α1. In addition, the sample used the thing which laminated copper foil on both surfaces of the obtained resin sheet, heat-cured on 200 degreeC and the conditions for 1 hour, and then removed the copper foil by etching.

(5) Evaluation of Semiconductor Device The semiconductor device obtained above was pretreated at a temperature of 30 ° C., a humidity of 60% and a time of 192 hours in accordance with IPC / JEDEC J-STD-20. The temperature was passed through a reflow furnace reaching 3 ° C. three times, and 500 cycles of −50 ° C. for 30 minutes and 125 ° C. for 30 minutes were performed as post-treatment. The evaluation was carried out by conducting resistance evaluation and cross-sectional observation of the semiconductor element after the pretreatment and after the temperature cycle of 500 cycles. The evaluation results are shown in Table 2.
Each code is as follows.
A: No abnormality in conduction resistance after 500 cycles of post-treatment, and no abnormality in conductor circuit and via in cross-sectional observation.
○: Although the conduction resistance after 500 cycles of post-treatment is increased in the range of less than 1 to 10%, there is no abnormality in the conductor circuit and via in the cross-sectional observation.
X: The conduction resistance after 500 cycles of post-treatment is increased by 10%. Or micro voids or peeling cracks occur between the conductor circuit and the resin, or between the via and the resin.

In addition, for Reference Example 2 and Comparative Example 1, cross-sectional photographs at the stage where grooves were formed in the insulating layer by laser and conductors were formed by electroless plating and electrolytic plating are shown in FIGS. 3 and 4, respectively. It was.

As is clear from Table 2, Examples 4, 6, 8, 10-15 , and 17 and Reference Examples 1 to 3, 5, 7 , 9 , and 16 have an arithmetic average roughness (Ra) of 0 on the insulating layer surface. The surface roughness was good low roughness of 0.05 μm or more and 0.45 μm or less, and the 10-point average roughness (Rz) of the conductor layer wall surface was 5.0 μm or less. Since the surface roughness of the insulating layer surface is optimized in this way, the insulation reliability of the fine wiring is excellent. In addition, good fine wiring with excellent signal response was formed.
On the other hand, in Comparative Examples 1 and 2, since the coarse particle removal is not sufficient in addition to the large particle size of the inorganic filler, the 10-point average roughness (Rz) of the conductor layer wall surface is large and the distance between the conductor wirings is large. Since it is very close, the insulation reliability of fine wiring is inferior. In addition, Ra on the surface of the insulating layer is large and is not suitable for forming fine wiring. In Comparative Example 3, the average particle size is the same as that of the example, but since the removal of coarse particles is not sufficient, the 10-point average roughness (Rz) of the conductor layer wall surface is large and the distance between the conductor wirings is very close. Therefore, the insulation reliability of fine wiring is inferior. In addition, Ra on the surface of the insulating layer is large and is not suitable for forming fine wiring.

According to the present invention, a printed wiring board having fine wiring corresponding to high adhesion, high reliability, and high frequency formed on the surface of the resin layer of the printed wiring board can be obtained. / S) can be suitably used for a printed wiring board having fine wiring of 10 μm / 10 μm or less.

DESCRIPTION OF SYMBOLS 1 Base material 2 Resin layer 4 Conductor layer 5 Glass epoxy base material 6 Laser light 7 Groove 8 Electroless plating layer 9 Electrolytic plating layer 10 Conductor 11 Conductor layer 20 Insulating layer 30 Resin sheet 40 Another insulating layer 50 Inner circuit board

Claims (6)

A resin composition comprising an inorganic filler and a thermosetting resin, wherein the inorganic filler has a coarse particle exceeding 2 μm in an amount of 500 ppm or less, and the thermosetting resin comprises a naphthalene-modified cresol novolac epoxy resin and a novolac Type cyanate resin combination,
Characterized in that it comprises a naphthalene dimethylene type epoxy resin, and one or more resins selected from among benzocyclobutene resin, wiring boards used for the insulating layer of the circuit formed by digging directly grooves by laser processing on a surface Resin composition.   The resin composition for a wiring board according to claim 1, wherein the inorganic filler has an average particle size of 0.05 μm or more and 1.0 μm or less.   The resin composition for a wiring board according to claim 1 or 2, wherein the content of the inorganic filler is 10 to 80% by weight in the resin composition.   The resin composition for a wiring board according to any one of claims 1 to 3, wherein the inorganic filler is spherical silica.   The resin composition for a wiring board according to any one of claims 1 to 4, wherein the resin composition contains 5 to 12% by weight of a thermoplastic resin, and the thermoplastic resin is a phenoxy resin. A resin for a wiring board used for an insulating layer formed by forming a resin layer comprising the resin composition according to any one of claims 1 to 5 on a substrate and forming a circuit by directly digging a groove on the surface by laser processing. Sheet.