JP4922207B2 - Manufacturing method of multilayer insulating film and multilayer printed wiring board - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer insulating film and a multilayer printed wiring board, and more specifically, a method for manufacturing a multilayer insulating film in which a first layer and a second layer are difficult to peel off, and a multilayer insulation obtained by this manufacturing method. The present invention relates to a method for manufacturing a multilayer printed wiring board in which a film is laminated on a circuit board.

  In recent years, with the demand for smaller and lighter IT equipment, multilayer printed wiring boards are required to be thinner, denser and more reliable. The demand for higher density is increasing not only in the surface direction of the multilayer printed wiring board but also in the thickness direction. In order to meet this demand, the thickness of the insulating layer has been reduced. However, if the thickness is reduced, the electrical signal due to the nonuniformity of the interlayer connection distance due to the nonuniformity of the layer thickness is obtained. There is a problem such as delay. In addition, in order to increase the density in the thickness direction, a method of incorporating electrical components, semiconductor elements, etc. in the multilayer printed wiring board is taken, but insulating resin is filled between the wiring board and the components. There is a problem that voids are easily generated.

For example, in Patent Document 1, by using two types of adhesive sheets having different minimum melt viscosities, the inner layer through-hole is filled with a resin having a lower minimum melt viscosity, and a resin having a higher minimum melt viscosity is uniform. It is said that an insulating layer with little thickness variation is formed.
In Patent Document 2, a through hole is provided in an inner insulating substrate, a component is placed thereon, an insulating base material and a conductor base material are stacked, and at the same time as this stacking, the component is sealed with the insulating base material. There is disclosed a method of manufacturing a component built-in type printed wiring board having a step of This through-hole improves the resin flowability of the insulating base material, so that no trouble factors such as voids are generated in the lower part and the periphery of the part.

However, in the adhesive sheet and the laminating method disclosed in Patent Document 1, when the unevenness on the circuit board becomes large or the hole such as a through hole becomes large, the flatness of the surface of the insulating layer is not good. May be sufficient. Further, the printed circuit board disclosed in Patent Document 2 requires a through hole under the component, and it is not preferable that there is such a restriction in the recent demand for higher density.
JP 2005-123436 A JP 2006-41000 A

  In view of the state of the prior art described above, the object of the present invention is to create voids in the substrate when a multilayer insulating film is laminated on a circuit board having a hole such as a through hole or a via hole or a circuit board having irregularities such as a circuit pattern. A method for producing a multilayer insulation film that is difficult, has a sufficient surface flatness, can maintain a uniform thickness of the first layer of the multilayer insulation film, and is difficult to peel off from the first layer and the second layer, and this production method It is providing the manufacturing method of the multilayer printed wiring board which laminated | stacked the obtained multilayer insulation film on the circuit board.

  As a result of intensive studies to solve the above problems, the present inventors have found that in a method for producing a multilayer insulating film comprising a base material and a two-layer insulating layer, the insulating layer comprises an epoxy resin or the like. The resin composition containing a specific amount of a specific polymer material is formed into a film and cured so that the gel fraction is 60 to 94% when immersed in dimethylformamide at room temperature for 10 minutes. When formed through a first step of producing a cured film and a second step of laminating a second layer made of a resin composition containing an epoxy resin or the like on the cured film, the first layer and the first layer It has been found that the thicknesses of the two layers can be made uniform and the above-mentioned problems are achieved. Based on these findings, the present invention has been further studied and completed.

That is, according to the first aspect of the present invention, the substrate (B) and the insulating layer (A) composed of the first layer (A1) and the second layer (A2) in contact with the substrate (B) are provided. The insulating layer (A) contains a thermosetting resin (a1), a curing agent (b1), an inorganic filler (c1), and a resin having a weight average molecular weight of 5000 or more. A resin composition (I) comprising a polymer material (d) to be produced, wherein the resin composition (I) comprises 5 to 60% by weight of the resin having a weight average molecular weight of 5000 or more based on the total amount of the composition (I) And the first step of producing a cured film of the first layer (A1), followed by curing so as to have a gel fraction of 72 to 94% when immersed in dimethylformamide at room temperature for 10 minutes, The cured film has a thermosetting resin (a2) and a curing agent (b2). And a second step of laminating the second layer (A2) composed of the resin composition (II) containing 30 to 90% by weight of the inorganic filler (c2) based on the total solid content of the composition (II). The manufacturing method of the multilayer insulation film characterized by being formed is provided.

According to a second invention of the present invention, in the first invention, the multi-layer insulation is characterized in that the curing temperature when producing the cured film of the first layer (A1) is in the range of 130 to 150 ° C. A method of manufacturing a film is provided.
According to a third invention of the present invention, in the first invention, the resin having a weight average molecular weight of 5000 or more contained in the polymer material (d) is a phenoxy resin. A manufacturing method is provided.
Furthermore, according to a fourth aspect of the present invention, in the first aspect, the inorganic filler (c1) is silica that has been surface-treated with an imidazole silane coupling agent, and the silica is a composition ( There is provided a method for producing a multilayer insulating film, which is contained in an amount of 5 to 50% by weight based on the total solid content of I).

According to a fifth aspect of the present invention, in the first aspect, the inorganic filler (c2) contains silica and a layered silicate, and the layered silicate is a solid content of the composition (II). Provided is a method for producing a multilayer insulating film, wherein the content is 0.01 to 5% by weight based on the total amount.
Furthermore, according to a sixth aspect of the present invention, in the first aspect, the thermosetting resin (a1, a2) is an epoxy resin, and the curing agent (b1, b2) is a phenol compound. There is provided a method for producing a multilayer insulating film characterized in that:

  On the other hand, according to 7th invention of this invention, 2nd layer (A2) opposes a circuit board in the multilayer insulation film obtained from the manufacturing method of the multilayer insulation film in any one of 1st-6th invention. The first step of placing on the circuit board and heating and pressurizing at a temperature of 60 to 200 ° C. and a pressure of 1 to 30 MPa, and heating the multilayer insulating film at a temperature of 60 to 140 ° C. Including a second step and a third step of heating the multilayer insulating film at a temperature in the range of 140 to 200 ° C. that is 20 ° C. higher than the temperature of the second step. A method for producing a multilayer printed wiring board is provided.

  According to the method for producing a multilayer insulating film of the present invention, the thickness of each of the first layer and the second layer can be made uniform, and the multilayer insulating film is applied to a circuit board having a hole such as a through hole or an unevenness such as a via hole. Even in the case of lamination, a multilayer in which voids are hardly generated, surface flatness is sufficiently secured, the thickness of the first layer of the multilayer insulating film can be kept uniform, and the first layer and the second layer are difficult to peel off. A method for producing an insulating film can be provided. Moreover, the manufacturing method of the multilayer printed wiring board which can keep constant the insulation thickness of the multilayer printed wiring board which laminated | stacked the multilayer insulating film obtained by this manufacturing method on a circuit board can be provided.

Hereinafter, details of the present invention will be described for each item. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.
The manufacturing method of the multilayer insulation film of this invention comprises the base material (B) and the insulating layer (A) which consists of a 1st layer (A1) and 2nd layer (A2) which contact | connect a base material (B). The insulating layer (A) comprises a thermosetting resin (a1), a curing agent (b1), an inorganic filler (c1), and a resin having a weight average molecular weight of 5000 or more. I) A resin composition (I) containing a polymer material (d) contained in an amount of 5 to 60% by weight based on the total amount is formed into a film and has a gel fraction of 60 to 60 when immersed in dimethylformamide at room temperature for 10 minutes. The first step of curing to 94% to produce a cured film of the first layer (A1), and subsequently, the cured film, a thermosetting resin (a2), a curing agent (b2), and a composition 30 to 90% by weight of inorganic filler based on the total solid content of (II) Through a second step of laminating a second layer comprising the resin composition (II) and (A2) containing c2), it is characterized in being formed.

1. Multilayer Printed Wiring Board and Multilayer Insulating Film A multilayer printed wiring board according to the present invention includes a multilayer insulating film obtained from the production method of the present invention, a circuit board and a printed board (collectively referred to as a circuit board and a printed board) It is called “circuit board”.)
This multilayer insulating film comprises (a) a base material (B) and (b) a thermosetting resin (a), a curing agent (b) and an inorganic filler (c), or a polymer material (d) as a raw material. ) And / or a resin composition (I, II) containing a curing accelerator (e), the polymer material (d) contains 5 to 60% by weight of a resin having a weight average molecular weight of 5000 or more, and a base material ( The first layer (A1) in contact with B) and the second layer (A2) provided on the first layer and containing 30 to 90% by weight of the total amount of the inorganic filler (c) are laminated. And an insulating layer (A).
That is, the multilayer insulating film is laminated | stacked in order of the base material (B), the 1st layer (A1), and the 2nd layer (A2). A layer equivalent to the first layer or the second layer may be additionally stacked between the first layer and the second layer. In addition, an adhesive, a primer, or the like may be applied and laminated between layers, and when these adhesives, primers, or the like are inserted between layers, the interlayer strength is increased. This is preferable.

Further, by containing 5 to 60% by weight of the polymer material (d) having a weight average molecular weight of 5000 or more in the first layer (A1), a non-fluidized layer (high viscosity layer that does not flow even when pressure is applied during pressing) ) Can be formed and the initial thickness can be maintained, so that the desired insulating layer thickness can be achieved.
Further, by adding a large amount of the inorganic filler (c) to the second layer (A2) to form a high fluidity layer (fluidized layer), the surface has holes such as via holes and circuit pattern irregularities on the substrate. In addition, when an insulating film composed of the first layer and the second layer is laminated, a difference in contraction rate due to the site is unlikely to occur, the surface flatness of the resin sheet is sufficiently secured, and the insulating layer thickness is kept constant. A sacrificial multilayer printed wiring board can be obtained.
Since the second layer has a total amount of inorganic filler of 30 to 90% by weight, the amount of shrinkage after resin flow during pressing can be reduced, so that sufficient flatness can be secured.

  The circuit board used for the multilayer printed wiring board according to the present invention is not particularly limited. For example, the substrate such as a board having a through-hole via, a board having a blind via, a board wired with a metal, etc. The substrate is not flat but has irregularities. Here, the material of the substrate is not particularly limited.

  The multilayer printed wiring board according to the present invention is less likely to cause a difference in shrinkage due to the laminated portion of the multilayer insulating film, even when the multilayer insulating film is laminated on a circuit board having irregularities such as via holes and circuit patterns. It has a very good thickness accuracy and sufficiently ensures the surface flatness of the multilayer insulating film. For this reason, the multilayer printed wiring board according to the present invention has less variation in the electrical resistance in the thickness direction and the length of the electrical signal when the circuit is formed on the circuit board using the metal wiring, and the signal noise is reduced. Etc. can be reduced.

2. The material which comprises a multilayer insulation film The 1st layer, 2nd layer, and base material which comprise the multilayer insulation film obtained by the manufacturing method of this invention are demonstrated.
(1) First layer (A1)
First, the first layer (A1) constituting the insulating layer (A) of the multilayer insulating film according to the present invention will be described.
The first layer (A1), which is the high-viscosity layer (non-fluidized layer) of the insulating layer (A), is made of a thermosetting resin (a1), a curing agent (b1), an inorganic filler (c1), and a polymer. It consists of resin composition (I) containing material (d). The resin composition (I) preferably contains a curing accelerator (e).
The polymer material (d) is not particularly limited as long as the weight average molecular weight is 5000 or more, and conventionally known polyacetal, polyimide, polycarbonate, modified polyphenylene ether (PPE), polybutylene terephthalate (PPB), polysulfone, Engineer plastics such as polyethersulfone and polyetherimide, resins obtained by adding functional groups to these resins, and high molecular weight thermosetting resins such as phenoxy resins can be used.
Among these, in producing the first layer (A1) of the multilayer insulating film according to the present invention, a phenoxy resin is used from the viewpoint of compatibility with an epoxy resin which is a thermosetting resin (a1) described later used as a raw material. Is preferably used.

  The weight average molecular weight of the polymer material (d) is preferably 5000 or more, more preferably 20000 or more. If the weight average molecular weight is less than 5,000, the viscosity of the polymer material becomes low at high temperatures. For example, when the circuit board is heated and pressed using a vacuum press machine, the first layer has a uniform insulation thickness. There is a tendency to be unable to maintain. Moreover, since it is desirable that the polymer material (d) has a high thickening effect when added in a small amount, a higher molecular weight can be preferably used.

The polymer material (d) is preferably 5 to 60% by weight, more preferably 30 to 50% by weight, based on the entire raw material used, that is, the total amount of the resin composition (I). If it is less than 5% by weight, the viscosity of the entire raw material mixture is lowered, and the first layer tends to be unable to maintain a uniform insulation thickness when it is heat-pressed to a circuit board using, for example, a vacuum press. . On the other hand, when it exceeds 60% by weight, the viscosity of the entire raw material mixture increases excessively, and voids tend to be generated.
In the present invention, the polymer material (d) suppresses fluidity by increasing the viscosity of the first layer, hardly flows during pressing, and can ensure flatness even after the pressure is released. Plays. That is, the smoothness of the surface of the laminated substrate on which the circuit board and the multilayer insulating film are laminated can be improved.

A conventionally well-known epoxy resin can be used for the thermosetting resin (a1) as a raw material of the 1st layer (A1) of the insulating layer (A) which comprises the multilayer insulating film which concerns on this invention.
Examples of the epoxy resin include organic compounds having at least one epoxy group (oxirane ring). The number of epoxy groups in the epoxy resin is preferably 1 or more per molecule, and more preferably 2 or more per molecule.
As an epoxy resin, for example,
(I) aromatic epoxy resins such as bisphenol-type epoxy resins and epoxy resins having a biphenyl structure;
(Ii) alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate,
(Iii) an aliphatic epoxy resin such as diglycidyl ether of neopentyl glycol;
(Iv) Glycidyl ester type epoxy resin such as diglycidyl phthalate,
(V) glycidylamine type epoxy resins such as triglycidyl isocyanurate and tetraglycidyldiaminodiphenylmethane,
(Vi) a glycidyl acrylic epoxy resin such as a copolymer of glycidyl (meth) acrylate and a radical polymerizable monomer such as ethylene, vinyl acetate, (meth) acrylic acid ester,
(Vii) a polyester type epoxy resin such as a polyester resin having one or more, preferably two or more epoxy groups per molecule;
(Viii) an epoxy resin obtained by epoxy-modifying a compound having an unsaturated carbon double bond in a polymer mainly composed of a conjugated diene compound such as epoxidized polybutadiene and epoxidized dicyclopentadiene or a partially hydrogenated polymer thereof;
(Ix) Styrene-butadiene block copolymer, styrene-isoprene block copolymer, styrene-isoprene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-butylene -Epoxy resins that are epoxy-modified into styrene block copolymers, etc., or hydrogenated compounds thereof,
(X) Furthermore, a urethane-modified epoxy resin or a polycaprolactone-modified epoxy resin in which a urethane bond or a polycaprolactone bond is introduced into the structure of the epoxy resin,
Etc.
Among these, from the viewpoint of improving the solubility of raw materials in solvents when manufacturing insulating films and improving moldability, bisphenol-type epoxy resin improves the durability and chemical resistance of insulating films, and further improves heat resistance. From the viewpoints of reducing water absorption, improving dimensional stability against thermal history and improving electrical characteristics, it is preferable to use an epoxy resin having a biphenyl structure. An epoxy resin may be used independently and 2 or more types may be used together.

  Examples of the epoxy resin include 1) a derivative of an epoxy resin such as a flexible epoxy resin having a butadiene skeleton in the molecule, 2) a hydrogenated product of the epoxy resin, 3) a thermosetting modified polyphenylene ether resin, and a benzoate. A resin copolymerizable with an epoxy resin such as an oxazine resin may be contained.

Examples of the curing agent (b1) as a raw material for the first layer of the multilayer insulating film include a phenol compound, an amine compound, a compound synthesized from an amine compound, a tertiary amine compound, an imidazole compound, a hydrazide compound, a melamine compound, and an acid. Examples thereof include anhydrides, active ester compounds, thermal latent cationic polymerization catalysts, photolatent cationic polymerization initiators and derivatives thereof.
Among these, from the viewpoint of improving the electrical properties, mechanical properties and moldability of the resin composition, the phenol compound is used, and in particular, the heat resistance of the resin composition is improved, the water absorption is reduced, and the dimensional stability with respect to the thermal history is imparted. From the viewpoint of improving the electrical properties and electrical characteristics, it is preferable to use a phenol compound having a biphenyl structure. These hardening | curing agents may be used independently and 2 or more types may be used together.

  The blending ratio of the curing agent (b1) is not particularly limited as long as the object of the present invention is not impaired, but is preferably 1 to 200 parts by weight with respect to 100 parts by weight of the epoxy resin that is the thermosetting resin (a1). . When the amount of the curing agent (b1) is less than 1 part by weight, the epoxy resin may not be sufficiently cured, while when it is more than 200 parts by weight, it may be excessive to cure the epoxy resin.

As the inorganic filler (c1) as the raw material of the first layer (A1) of the insulating layer, silica, layered silicate, talc, dielectric ceramic powder, aluminum, magnesium, silicon, zinc, calcium, strontium, zirconium, Examples thereof include metal oxide powders containing metal elements such as barium, tin, neodymium, bismuth, lithium, samarium, and tantalum.
The content of the inorganic filler (c1) is preferably 5 to 70% by weight with respect to the total solid content of the resin composition (I) in the first layer. More preferably, it is 10 to 50% by weight. If it is less than 5% by weight, there is a tendency that the fluidity suppressing effect is small when fluidity occurs in the polymer material at a high temperature. On the other hand, if it exceeds 70% by weight, the strain cannot be absorbed and cracking tends to occur when pressurization and heating / cooling are repeated.

Silica as the inorganic filler (c1) is, for example, crystalline silica obtained by pulverizing natural silica raw material, crushed fused silica and spherical fused silica obtained by flame melting and pulverization, fumed silica (Aerosil), or sol-gel. Examples thereof include synthetic silica obtained by a method.
Here, since synthetic silica often contains ionic impurities, it is preferable to use fused silica in terms of purity. Although it does not specifically limit as a shape of a silica, A perfect spherical shape, an indefinite shape, etc. are mentioned. As for the particle diameter of silica, it is preferable that the average particle diameter is 0.01 to 2.00 μm and the maximum particle diameter is 5.00 μm or less from the viewpoint of fine pattern formation of fine metal wiring.

Moreover, it is preferable that the silica used as an inorganic filler (c1) for the raw material of the 1st layer of a multilayer insulation film is surface-treated, and a silane coupling agent, a titanate coupling agent, an aluminum coupling is carried out. An agent or the like can be used.
Silica is preferably surface-treated with an imidazole silane coupling agent from the viewpoint that a fine anchor (rough surface) can be formed by pre-plating treatment to form a fine pattern.
Furthermore, the content of the silica surface-treated with the imidazole silane coupling agent used in the first layer is 5 to 50% by weight with respect to the total solid content of the resin composition (I) in the first layer. preferable. More preferably, it is 10 to 30% by weight. If it is less than 5% by weight, the roughening peel tends to be low. On the other hand, when it exceeds 50% by weight, the resin component is decreased, and therefore, the insulating film tends to be scraped with the treatment liquid when pre-treatment of plating, and the roughening peel tends to be lowered.

The layered silicate used as the inorganic filler (c1) as the raw material of the first layer of the multilayer insulating film means a layered silicate mineral having an exchangeable metal cation between layers, and even if it is a natural product, it is a synthetic product. May be.
By using a layered silicate having a large aspect ratio as the layered silicate, the mechanical properties of the obtained insulating film can be improved.
Examples of the layered silicate having a large aspect ratio include smectite-based viscosity minerals, swellable mica, vermiculite, and halloysite.
Examples of the smectite-based viscosity mineral include montmorillonite, hectorite, saponite, beidellite, stevensite, and nontronite.
Among these, at least one selected from the group consisting of montmorillonite, hectorite, and swellable mica is preferably used as the layered silicate.
Moreover, these layered silicates may be used independently and 2 or more types may be used together.
The layered silicate is preferably an organic layered silicate. The organic layered silicate is a known organic treatment, for example, a layer having a carbon number of 6 or more between crystal layers of the layered silicate for the purpose of improving the dispersibility in the resin and the cleavage property. Cation exchange may be performed with a quaternary ammonium salt or a quaternary phosphonium salt having an alkyl group.

The layered silicate is preferably 0.01 to 20% by weight based on the total solid content of the resin composition (I) in the first layer. More preferably, it is 0.01 to 10 weight%. When the content is less than 0.01% by weight, the effect of suppressing fluidity tends to be small when fluidity occurs in the polymer material at high temperatures. On the other hand, if it exceeds 20% by weight, the strain cannot be absorbed and cracking tends to occur when pressurization and heating / cooling are repeated.
When the layered silicate is used in combination with silica, even when the amount of the inorganic filler (c1) is relatively large, it becomes difficult to scrape the insulating film with the treatment liquid when the pretreatment for plating is performed, and the reduction of the roughening peel is suppressed. In this case, it is preferable that it is 0.01 to 10 weight% with respect to the total solid content of the resin composition (I) in a 1st layer, More preferably, it is 0.01 to 2 weight%.

  In addition to the thermosetting resin (a1), the curing agent (b1), the inorganic filler (c1) and the polymer material (d), the resin composition (I) of the first layer of the multilayer insulating film includes: It is preferable to further contain a curing accelerator (e) as necessary. Heat hardening can be made appropriate by mix | blending a hardening accelerator (e) with resin composition (I).

  Examples of the curing accelerator (e) include 2-ethyl-4-methylimidazole (2E4MZ), 1-cyanoethyl-2-ethyl-4-methylimidazole (2E4MZ-CN), 1-cyanoethyl-2-undecylimidazole ( C11Z-CN), 1-cyanoethyl-2-phenylimidazole (2PZ-CN), 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-S-triazine (2MZA-PW) 2,4-diamino-6- [2'-undecylimidazolyl- (1 ')]-ethyl-S-triazine (C11Z-CN), 2,4-diamino-6- [2'-ethyl-4' -Methylimidazolyl- (1 ')]-ethyl-S-triazine (2E4MZ-A), 2,4-diamino-6- [2'-methylimidazolyl- (1') -Ethyl-S-triazine isocyanuric acid adduct (2MAOK-PW), 2-phenylimidazole isocyanuric acid adduct (2PZ-OK), 2-phenyl-4,5-dihydroxymethylimidazole (2PHZ-PW), 2-phenyl -4-methyl-5-hydroxymethylimidazole (2P4MHZ-PW), 2,4-diamino-6-vinyl-S-triazine (VT) and the like.

  Although content of a hardening accelerator (d) is not specifically limited, 0.1-10 weight% is preferable with respect to the resin component of resin composition (I), and 0.5-5 weight% is especially preferable. When the content is less than the lower limit, the epoxy resin as the thermosetting resin (a1) is insufficiently cured. On the other hand, when the content exceeds the upper limit, self-polymerization of the epoxy resin occurs, and the curing agent (b1). The epoxy resin curing reaction may be hindered and the storage stability may be reduced.

  The first layer (A1) of the insulating layer is used as necessary in addition to the thermosetting resin (a1), the curing agent (b1), the inorganic filler (c1), and the polymer material (d). In addition to the curing accelerator (e), as long as the object of the present invention is not impaired, as necessary, as a raw material, thermoplastic resins, thermoplastic elastomers, crosslinked rubber, oligomers, inorganic compounds, nucleating agents, oxidation Additives such as antioxidants, anti-aging agents, heat stabilizers, light stabilizers, UV absorbers, lubricants, flame retardant aids, antistatic agents, antifogging agents, fillers, softeners, plasticizers, and colorants May be blended. These may be used independently and 2 or more types may be used together.

(2) Second layer (A2)
Next, the second layer (A2) constituting the insulating layer (A) of the multilayer insulating film according to the present invention will be described.
The second layer (A2), which is the fluidized layer of the insulating layer (A), is different from the first layer (A1), which is the high-viscosity layer, as a raw material, the thermosetting resin (a2), the curing agent (b2), and It consists of resin composition (II) containing an inorganic filler (c2), and the polymer material (d) is not an essential component. The resin composition (II) preferably contains a curing accelerator (e) as in the case of the resin composition (I).

As the inorganic filler (c2) of the second layer (A2) of the insulating layer (A), silica and layered silicate are preferably contained. As silica and layered silicate used in the second layer (A2) of the insulating layer (A), the total amount of the solid component of the resin composition (II) used in the second layer is 30 to 90% by weight. The content is preferable, and silica and layered silicate used in the first layer (A1) of the multilayer insulating film can be used.
When the total content of silica and layered silicate is less than 30% by weight, the ratio of the resin content to the entire solid content increases, and when an insulating film is produced using such a raw material mixture, coating is performed. During the subsequent heat treatment, the curing shrinkage rate increases. From this, the thicker coating thickness part is larger than the shrinkage of the coating thickness part, resulting in the case where the multilayer insulation film is laminated on the circuit board and the multilayer printed circuit board is obtained. The unevenness on the surface of the multilayer printed board tends to increase, and there is a risk that sufficient flatness cannot be ensured. On the other hand, when the total content of silica and layered silicate exceeds 90% by weight, the viscosity of the raw material mixture tends to be high, and the handleability during the production of the insulating film tends to be lowered. Considering such a tendency, the more preferable total content of silica and layered silicate is 45 to 70% by weight.

  The layered silicate as the inorganic filler (c2) of the second layer is preferably 0.05 to 5% by weight or less with respect to the total solid content of the resin composition (II) of the second layer. More preferably, it is 0.1 to 3% by weight. When the amount is less than 0.05% by weight, non-uniformity in the fluidity of silica occurs when filling through holes and the like, and there is a tendency for non-uniformity in the effect of suppressing curing shrinkage and mechanical strength. On the other hand, when it exceeds 5% by weight, the fluidity deteriorates due to thickening, and the filling property to via holes and the like tends to be lowered.

A conventionally well-known epoxy resin can be used for the thermosetting resin (a2) as a raw material of the 2nd layer (A2) of an insulating layer (A). That is, the epoxy resin as a raw material for the second insulating layer is not particularly limited, and an epoxy resin that is the thermosetting resin (a1) used in the first layer of the multilayer insulating film can be used.
Similarly to the above, the curing agent (b2) as a raw material of the second layer (A2) of the insulating layer (A) is not particularly limited, and the curing agent used in the first layer (A1) of the multilayer insulating film. (B1) can be used.
Further, similarly to the above, the curing accelerator (e) used as necessary as the raw material of the second layer (A2) of the insulating layer (A) is not particularly limited, and the first layer ( The curing accelerator (e) used in A1) can be used.

  The second layer (A2) of the insulating layer (A) is an object of the present invention, in addition to the thermosetting resin (a2), the curing agent (b2), the inorganic filler (c2), and the curing accelerator (e). Unless necessary, thermoplastic resins, thermoplastic elastomers, crosslinked rubber, oligomers, inorganic fillers other than silica and layered silicate, nucleating agents, antioxidants, anti-aging agents, heat Additives such as a stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, a flame retardant aid, an antistatic agent, a softener, a plasticizer, and a colorant may be blended. These may be used independently and 2 or more types may be used together.

  The solid component contained in the resin composition (I, II) constituting the multilayer insulating film according to the present invention refers to a component that does not substantially volatilize even by heat curing. For example, a liquid resin or the like is a solid component, and a solvent or the like is not a solid component.

(3) Base material (B)
Examples of the base material (B) constituting the multilayer insulating film according to the present invention include resin-coated paper, polyester film, polyethylene terephthalate (PET) film, polypropylene (PP) film, copper foil, and the like. Furthermore, a mold release process may be performed.
Further, a protective film may be further laminated on the base material (B) in order to prevent adhesion of dust and the like. As such a thing, the film which can be used with a base material (B) can be used, and the same material as a base material (B) may be sufficient, and a different material may be sufficient as it.

When a multilayer printed circuit board is obtained by laminating a multilayer insulating film on a circuit board, a base material having a high elastic modulus such as a copper foil is preferable in order to reduce the unevenness on the surface of the multilayer printed board.
The substrate (B) may be used as it is for circuit pattern formation or may be peeled off. In order to peel off the base material, the base material can be peeled off mechanically or with a solubilizer capable of dissolving the base material. When the substrate is a copper foil, for example, a solution containing ferric chloride and the like can be mentioned. After peeling, a circuit can be formed after forming a conductor layer by copper plating or the like.

The surface roughness of the multilayer printed board from which the substrate (B) has been peeled tends to be smaller as the surface roughness of the original substrate (B) is smaller. On the other hand, if the surface roughness of the original base material is too small, peeling occurs between the base material (B) and the first layer (A1) of the multilayer insulating film in the laminating step, and as a result, unevenness on the surface of the multilayer printed board. There is a risk that the effect of reducing the thickness will fade.
As an example of a more preferable base material, a plastic film such as mat-treated PET or a low-roughness copper foil may be used. By combining the base material (B) having a small surface roughness and the first layer (A1) containing 5 to 50% by weight of imidazole silane-treated silica, a fine rough surface can be formed after the pretreatment for plating. For example, a fine pattern with L / S = 5 μm / 5 μm can be formed. In the future, with increasing integration of multilayer printed circuit boards, L / S becomes smaller and smaller, but it is difficult to form fine patterns with a large surface roughness, and the effectiveness of the present invention is very high. Conceivable.

  In addition, as a mold release treatment method, a film having releasability is allowed to contain a silicon compound, a fluorine compound, a surfactant, or the like, or the surface is provided with unevenness so as to have releasability, Examples thereof include a method of embossing satin or the like, and applying a release material such as a silicon compound, a fluorine compound, or a surfactant to the surface. In order to further protect the film having releasability, a protective film such as a resin-coated paper, a polyester film, a PET film, or a PP film may be laminated on the film having releasability.

3. Method for Producing Multilayer Insulating Film The method for producing a multilayer insulating film of the present invention uses the above-described constituent materials, and comprises a base material (B), and a first layer (A1) and a second layer (A2) in contact with the base material (B). The insulating layer (A) comprises a thermosetting resin (a1), a curing agent (b1), an inorganic filler (c1). ) And a polymer composition (I) containing a polymer material (d) containing 5 to 60% by weight of a resin having a weight average molecular weight of 5000 or more based on the total amount of the composition (I), and is formed into dimethylformamide at room temperature. The first step of making the cured film of the first layer (A1) is cured so that the gel fraction when immersed for 10 minutes is 60 to 94%, and subsequently, the cured film is thermoset. Resin (a2), curing agent (b2) and composition (II And the second step of laminating the second layer (A2) made of the resin composition (II) containing 30 to 90% by weight of the inorganic filler (c2) based on the total solid content. It is characterized by.
And it is preferable that the curing temperature at the time of producing the cured film of said 1st layer (A1) is the range of 130-150 degreeC.

As a method for forming the insulating layer (A), the first step is to laminate the first layer (A1) made of the resin composition (I) on the base material (B) and immerse in dimethylformamide at room temperature for 10 minutes. It is the process of making it harden | cure so that the gel fraction may become 60%-94%, forming in a film form, and producing the cured film of the 1st layer (A1). The lamination method is not particularly limited. For example, the above resin composition (I) is dissolved in a predetermined solvent, a varnish dissolved at a predetermined concentration is applied to the base material (B), and then dried and cured. It is preferable to carry out the production.
As the solvent used for the varnish, it is preferable to select a solvent having good solubility in the resin composition. For example, acetone, methyl ethyl ketone, toluene, xylene, n-hexane, methanol, ethanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methoxypropanol, cyclohexanone, N-methylpyrrolidone, dimethylformamide (DMF), dimethylacetamide, etc. Or it is possible to use a mixture of two or more. In particular, DMF, cyclohexanone, hexane and the like are preferable.
The curing temperature for producing the cured film is preferably 130 to 150 ° C. When the curing temperature is less than 130 ° C., the resin composition (I) is not sufficiently cured. On the other hand, when the curing temperature is higher than 150 ° C., the solvent in the varnish after coating is rapidly evaporated. Since marks remain, there is a risk of poor appearance. Moreover, it is preferable that hardening time is 10 minutes-20 minutes. When the curing time is 10 minutes or less, the resin composition (I) is not sufficiently cured. On the other hand, when the curing time is 20 minutes or more, the resin composition (I) is sufficiently cured, but the productivity of the first layer (A1) is lowered.
Moreover, about the thickness of a cured film, although it does not specifically limit, it is 10 micrometers or more and 100 micrometers or less by a use.

Moreover, the 2nd process as a formation method of an insulating layer (A) is a process of laminating | stacking the 2nd layer (A2) which consists of resin composition (II) on the cured film obtained at said 1st process. is there. The laminating method is not particularly limited. For example, the resin composition (II) is dissolved in a predetermined solvent in a predetermined concentration in the same manner as the first layer (A1) made of the resin composition (I). It is preferable to produce the varnish by drying the cured film obtained in the first step at 80 ° C. or more and 150 ° C. or less after coating. About the thickness of the resin composition after drying, it coats so that it may become the range of 10 micrometers or more and 200 micrometers or less by a use.
As the solvent used for the varnish, it is preferable to select a solvent having good solubility in the resin composition as in the case of the resin composition (I).

  The method for producing the multilayer insulating film of the present invention is not particularly limited except for the method for forming the insulating layer (A). For example, (a) thermosetting resin, curing agent, polymer material, inorganic filler Extrusion method that melts and kneads raw materials such as extruders after extrusion and forms into a sheet (film) using a T-die or a circular die, (b) thermosetting resin, curing agent, polymer material Casting molding method in which raw materials such as inorganic fillers are dissolved or dispersed in a solvent such as an organic solvent and then cast into a sheet (film), (c) Other conventionally known sheet (film) molding Law.

  The multilayer insulating film according to the present invention is laminated in the order of the base material (B), the first layer (A1), and the second layer (A2). The procedure for producing the multilayer insulating film is not particularly limited except for the method for forming the insulating layer (A). Moreover, the 1st layer (A1) and the 2nd layer (A2) can perform the drying process and heat processing of a solvent simultaneously or independently as needed. In addition, it is preferable to apply an adhesive, a primer, or the like between the layers so that the interlayer strength can be increased.

4). Next, a method for manufacturing a multilayer printed wiring board using the multilayer insulating film obtained by the manufacturing method of the present invention will be described using an example.
The method for producing a multilayer printed wiring board according to the present invention comprises: (a) preparing a multilayer insulation film obtained by the above production method, and placing the multilayer insulation film so that the second layer (A2) faces the circuit board. A first step of placing on a circuit board and heating and pressing at a temperature of 60 to 200 ° C. and a pressure of 1 to 30 MPa; and (b) after the first step, the multilayer insulating film is heated to a temperature of 60 to 140 ° C. And (c) after the second step, the multilayer insulating film is heated at a temperature in the range of 140 to 200 ° C. that is 20 ° C. higher than the temperature of the second step. And a third step of performing a temperature treatment.

  In the method for producing a multilayer printed wiring board according to the present invention, a circuit is formed on the circuit board by plating the surface of the circuit board or by laminating a copper foil. After forming the via holes, a multilayer insulating film can be laminated on the circuit board to obtain a multilayer printed wiring board. Furthermore, using this multilayer printed wiring board (the previous multilayer printed wiring board) as a circuit board, the surface of the previous multilayer printed wiring board is plated or laminated with a copper foil, etc. A circuit is formed on top and, if necessary, through holes and via holes are formed in the previous multilayer printed wiring board, and then a multilayer insulating film is laminated on the previous multilayer printed wiring board to form a new multilayer printed wiring board. By repeating this procedure, a multilayer printed wiring board with more layers can be obtained.

  In the first step of the method for producing a multilayer printed wiring board, the second layer (A2) of the multilayer insulating film is placed on the circuit surface formed on the printed circuit board, and the temperature is 60 to 200 ° C. with a press. And pressurizing at a pressure of 1 to 30 MPa. The first to third steps may be performed with the same device or with different devices. If the same apparatus is used, it takes time to change the temperature and the productivity tends to be low, but the flatness is good. If another apparatus is used, a lot of equipment is required instead of having no time for temperature change.

  Examples of the heating and pressing apparatus used in the method for producing a multilayer printed wiring board according to the present invention include a heating press machine and a roll laminator. For example, when using a press, a known plate-like object such as a metal plate, a cushioning material, a release film, or a protective film having a smooth surface may be inserted between the press die and the base material of the multilayer laminated film. it can. Similarly, when a roll laminator is used, a cushion material, a release film, a protective film, or the like can be used.

  When a metal plate having a smooth surface is used between the press mold and the base material of the multilayer laminated film, the smoothness of the surface of the resulting multilayer printed board is improved. When a cushion material is used between the press die and the base material of the multilayer laminated film, pressure can be uniformly applied to the base material surface or the first layer surface, and the generation of voids can be further reduced. When a release film is used between the press die and the base material of the multilayer laminated film, the base material surface or the first layer surface ensures releasability with the metal plate or cushion material having a smooth surface. Can do. When a protective film is used between the press mold and the base material of the multilayer laminated film, dirt and scratches on the base material surface, the first layer surface, the second layer surface, and the like can be prevented. Moreover, it has the same effect as a release film.

  Similarly, when the press mold is in contact with the printed board, a known plate-like material such as a metal plate, a cushioning material, a release film, or a protective film having a smooth surface is placed between the press mold and the printed board. Can be inserted. Furthermore, surface smoothness can be stably obtained by moving each step while sandwiching a multilayer resin film and printed circuit board laminate between two metal plates.

  The base material (B) of the multilayer insulating film may be a single layer or a multilayer, and can be peeled off as necessary after the end of each step. Examples of the base material (B) include a PET film and a copper foil. If the substrate (B) is adhered without being peeled until the second step and the third step are finished, the unevenness caused by suppressing the curing shrinkage of the resin. Reduction can be expected. In addition, it can be expected to prevent dust from adhering.

  In the first step of the method for producing a multilayer printed wiring board, when heat-pressing after peeling off the substrate, the PET film that has been subjected to an appropriate release treatment, even after the second step and after the third step Can be peeled off. In the case of copper foil, the copper foil is etched while being rocked with ferric chloride at room temperature for 5 minutes. Etching may be performed using an etching apparatus. In addition to ferric chloride, cupric chloride and a general soft etchant can be applied. In addition, a conductor pattern may be formed by a subtractive method using a copper foil of a base material, or when the copper foil is 10 μm or less, a conductor pattern may be formed by a semi-additive method.

[First step]
In the first step of the method for producing a multilayer printed wiring board according to the present invention, the multilayer insulating film is heated in a vacuum press at a temperature of 60 to 200 ° C. with the second layer (A2) facing the circuit board. And it is the process of pressing at a pressure of 1-30 MPa. The press machine used for the manufacturing method of the multilayer printed wiring board concerning this invention is not specifically limited, A normal press machine etc. are used. Examples include Kitagawa Seiki's vacuum press and Mikado Technos' vacuum press. Hereinafter, the equipment used for heating and pressurization will be described using a vacuum press.

  In the method for producing a multilayer printed wiring board according to the present invention, the temperature during vacuum pressing is not particularly limited as long as it is 60 to 200 ° C. When the temperature is lower than 60 ° C., the viscosity of the second layer of the multilayer insulating film is not sufficiently lowered, and even when pressed, the flatness of the surface of the insulating film is difficult to be secured, and the filling is insufficient. There is a tendency that voids are generated in the via portion. On the other hand, when the temperature exceeds 200 ° C., the curing reaction of the resin constituting the second layer of the insulating film proceeds excessively, so that the viscosity of the resin is not sufficiently lowered. Since flatness of the film surface is difficult to be ensured and filling is insufficient, voids tend to occur in the via portion. Based on such a tendency, a more preferable temperature range at the time of vacuum pressing is 70 to 170 ° C.

  In the method for producing a multilayer printed wiring board according to the present invention, the pressure during vacuum pressing is not particularly limited as long as it is 1 to 30 MPa. If the pressure is less than 1 MPa, even if the pressing is performed, the second layer of the insulating film is not sufficiently filled, and thus there is a tendency that voids are generated in the via portion. On the other hand, if it exceeds 30 MPa, the unevenness of the base material affects the first layer of the multilayer insulating film, resulting in uneven thickness of the first layer, making it difficult to ensure the flatness of the surface of the insulating film, The thickness of the layer is reduced, and the insulating layer thickness tends not to be secured. Considering such a tendency, a more preferable pressure range at the time of vacuum pressing is 2 to 15 MPa.

  In the first step of the method for producing a multilayer printed wiring board according to the present invention, the shrinkage due to the thermal curing is minimized by preventing the thermal curing from being completely completed. Furthermore, the multi-layer insulation film can be gradually cured by taking the two-step heating process of the second step and the third step of the method for producing a multilayer printed wiring board according to the present invention, and rapid curing shrinkage It is possible to suppress the formation of local unevenness due to this, and to ensure flatness. Accordingly, the pressing time is not particularly limited, but from the viewpoint of sufficient filling of the insulating film to the concave surface of the substrate and ensuring sufficient surface flatness, efficiency of production work, etc., 2 to 40 minutes. Is preferred.

[Second step]
The second step of the method for producing a multilayer printed wiring board according to the present invention is a step of heat-treating the “multilayer insulating film with a circuit board” obtained after the first step at a temperature of 60 to 135 ° C. . Although it does not specifically limit about heat processing, For example, it performs using oven etc.

  In the method for producing a multilayer printed wiring board according to the present invention, the temperature during the heat treatment is not particularly limited as long as it is 60 to 140 ° C. When the temperature is lower than 60 ° C., the curing reaction of the resin constituting the first layer and the second layer of the multilayer insulating film is not sufficiently progressed, and the heat shrinkage of the resin is large during the subsequent heat treatment in the third step. Therefore, the flatness of the surface of the multilayer insulating film tends to be difficult to be ensured. On the other hand, when the temperature exceeds 140 ° C., the curing reaction of the resin constituting the first layer and the second layer of the multilayer insulating film proceeds rapidly, the thermal shrinkage of the resin increases, and the flatness of the surface of the multilayer insulating film Tends to be difficult to secure. Based on such a tendency, a more preferable temperature range during the heat treatment is 80 to 130 ° C.

  In addition, although it does not specifically limit about the heat processing time of a 2nd process, When the hardening reaction of the resin which comprises the 1st layer of a multilayer insulating film, and the 2nd layer, heat shrink, etc. are considered, it is 5-60. Minutes are preferred.

[Third step]
In the third step of the method for producing a multilayer printed wiring board, the “multilayer insulating film with a circuit board” obtained after the second step is at a temperature 20 ° C. or more higher than the temperature in the second step, and The heat treatment is performed at a temperature of 140 to 200 ° C. Although it does not specifically limit about heat processing, For example, it performs using oven etc.

  In the method for producing a multilayer printed wiring board according to the present invention, the temperature during the heat treatment is not particularly limited as long as it is 20 ° C. or more higher than the temperature in the second step and 140 to 200 ° C. The temperature at the time of the heat treatment in the third step in which the curing proceeds uniformly and stepwise needs to be 20 ° C. or higher than the temperature at the time of the heat treatment in the second step. Here, when the temperature during the heat treatment in the third step is less than 140 ° C., the progress of the curing reaction of the resin constituting the first layer and the second layer of the multilayer insulating film becomes insufficient, and as a result In addition, after the printed circuit board is manufactured by the method for manufacturing a multilayer printed wiring board according to the present invention, the surface of the multilayer insulating film is further subjected to swelling treatment / roughening treatment in order to wire fine metal on the surface of the multilayer insulating film. In this case, the damage to the surface of the multilayer insulating film may be increased. On the other hand, when the temperature during the heat treatment in the third step exceeds 200 ° C., the curing reaction of the resin constituting the first layer and the second layer of the multilayer insulating film proceeds rapidly, and the heat shrinkage of the resin It becomes large and tends to be difficult to ensure the flatness of the surface of the multilayer insulating film. Based on such a tendency, a more preferable temperature range during the heat treatment is 150 to 180 ° C.

  In addition, although it does not specifically limit about heat processing time, When considering the curing reaction of the resin which comprises the 1st layer and 2nd layer of a multilayer insulating film, a heat shrink, etc., 30 to 90 minutes are preferable.

  When forming a conductive pattern on the laminated multilayer printed wiring board by the semi-additive method, the resin surface is swollen, roughened, the plating catalyst is attached to the roughened resin surface, and further plated. The swelling treatment method is not particularly limited, and is performed by a conventionally known method. For example, a treatment method using an aqueous solution or a dispersion solution of an organic solvent containing a compound mainly composed of dimethylformamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, pyridine, sulfuric acid, sulfonic acid, and the like can be given. Among these, for example, a method of immersing and shaking the multilayer printed wiring board at a processing temperature of 60 to 85 ° C. for 1 to 20 minutes using an aqueous solution containing ethylene glycol is suitable.

  Moreover, it does not specifically limit as a method of roughening the surface of a multilayer insulation film, It performs by a conventionally well-known method. For example, manganese compounds such as potassium permanganate and sodium permanganate, chromium compounds such as potassium dichromate and anhydrous potassium chromate, and persulfate compounds such as sodium persulfate, potassium persulfate and ammonium persulfate are the main components. Examples thereof include a treatment method using an aqueous solution of a chemical oxidant and an organic solvent dispersion solution. Among these, for example, 30 to 90 g / L permanganic acid or permanganate solution, 30 to 90 g / L sodium hydroxide solution is used, and the above multilayer printed wiring is once or twice at a processing temperature of 70 to 85 ° C. A method in which the plate is immersed and swung is suitable. The step of attaching the plating catalyst to the roughened resin surface and the step of further plating can be performed by adopting a known method.

  In a multilayer printed wiring board, when a multilayer insulating film layer has a via hole, it is possible to perform a desmear process at the same time by performing a roughening process on the surface of the multilayer insulating film.

  By using the multilayer insulating film composed of the first layer (A1) having a high viscosity and the second layer (A2) containing a large amount of inorganic material and having a high fluidity, a via hole or the like is formed on the surface through the above process. Even when an insulating film is laminated on a substrate having uneven holes or circuit pattern irregularities, the difference in shrinkage due to the site is unlikely to occur, the surface flatness of the resin sheet is sufficiently secured, and the insulating layer thickness is constant. A multilayer printed wiring board maintained in the above can be obtained. Since the first layer (A1) contains 5 to 60% by weight of the polymer material (d) having a weight average molecular weight of 5000 or more, even if pressure is applied during pressing, the initial thickness can be maintained without flowing. Therefore, it is possible to finish the target insulating layer thickness, and by adding 5 to 50% by weight of silica surface-treated with an imidazole silane coupling agent which is a preferred embodiment, the rough surface after pre-plating treatment can be obtained. It can be made fine. On the other hand, since the second layer (A2) can reduce the amount of shrinkage after resin flow during pressing by setting the total amount of the inorganic filler (c2) to 30 to 90% by weight, sufficient flatness is ensured. be able to.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to a following example. In the examples and comparative examples, the following materials were used.

(Materials used):
[Epoxy resin (thermosetting resin)]
Biphenyl epoxy resin (1) (trade name “NC-3000FH”, epoxy equivalent 340, manufactured by Nippon Kayaku Co., Ltd.)
Bisphenol A type epoxy resin (2) (trade name “Epicoat 828US”, epoxy equivalent 183, manufactured by JER)
Biphenyl epoxy resin (3) (trade name “NC-3000H”, epoxy equivalent 288, manufactured by Nippon Kayaku Co., Ltd.)
Bisphenol F type epoxy resin (4) (trade name “EPICLON830S”, epoxy equivalent 168, manufactured by Dainippon Ink and Chemicals, Inc.)

[Epoxy resin curing agent]
Phenolic curing agent (1) (trade name “MEH7851-4H”, weight average molecular weight 10200 in terms of Pst, OH equivalent 241, manufactured by Meiwa Kasei Co., Ltd.)

[Curing accelerator]
Accelerator (1) (trade name “2MAOK-PW”, manufactured by Shikoku Kasei Co., Ltd.)
Accelerator (2) (trade name “Triphenylphosphine”, manufactured by Wako Pure Chemical Industries, Ltd.)

[Layered silicate (synthetic hectorite)]
Synthetic hectorite treated with trioctylmethylammonium salt [silica]
Silica silica (2) (manufactured by Admatechs, average) silica (1) (manufactured by Tatsumori Co., Ltd., average particle size 0.2 μm) surface-treated with imidazole silane (trade name “IM-1000” manufactured by Nikko Materials Co., Ltd.) Silica whose surface was treated with imidazole silane (trade name “IM-1000” manufactured by Nikko Materials Co., Ltd.)

[Polymer material]
Phenoxy resin (1) (trade name “YX6954BH30”, weight average molecular weight 39000 in terms of Pst, solid content 30%, MEK 35%, cyclohexanone 35%, manufactured by Japan Epoxy Resin Co., Ltd.)
Phenoxy resin (2) (trade name “1255HX30BPA type”, weight average molecular weight 49000 in terms of Pst, solid content 30%, xylene 35%, cyclohexanone 35%, manufactured by Japan Epoxy Resin Co., Ltd.)

[solvent]
N, N-dimethylformamide (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.)

[Example 1]:
<Production of circuit board>
On a glass epoxy board (trade name “FR-4”, product number “CS-3665 (100 mm × 100 mm × 0.4 mm)”, manufactured by Risho Kogyo Co., Ltd.) with a drill hole, φ300 μm, φ700 μm, φ1.5 mm through 50 holes were formed.
On the lower surface of the FR-4 substrate, NOVADURAN 5040ZS (Mitsubishi Engineering Co., Ltd.) is melted, and a film having a thickness of 80 μm formed by extrusion molding with a T die is laminated at 200 ° C. using a roll laminator. A circuit board (A) made of a glass epoxy substrate having one surface covered with a protective film was obtained.

<Production of multilayer insulation film>
As a base material, on copper foil (NA-DEF, manufactured by Mitsui Kinzoku Co., Ltd., mat surface, arithmetic average roughness (hereinafter Ra): 250 nm, ten-point average roughness (hereinafter Rz): 2.5 μm), After coating the resin mixture comprising the raw material composition constituting the first layer of the multilayer insulating film according to Example 1 to a finished film thickness of 20 μm with a die coater, 140 ° C. for 15 minutes in a heating and drying furnace. A cured film was obtained by heat treatment.

  Next, on the cured film, a resin mixture composed of the raw material composition constituting the second layer of Example 1 of Table 1 is coated with a die coater so as to have a film thickness of 120 μm, and then in a heating and drying furnace. Heat treatment for 12 minutes at 120 ° C., and a PET film (thickness: 35 μm, Ra: 70 nm, Rz: 1.2 μm, manufactured by Toyobo Co., Ltd.) as a protective film, A multilayer insulating film (C) composed of the first and second layers and the protective film was obtained.

<Press processing>
A multilayer insulating film (C ′) obtained by peeling off the protective film from the multilayer insulating film (C) was prepared. From the bottom, a SUS plate (200 mm × 200 mm × 1.5 mm), a circuit board (A) made of a glass epoxy substrate, a multilayer insulating film (C ′) (arranged so as to contact the circuit board on which the second layer is formed), SUS The plates (200 mm × 200 mm × 1.5 mm) were stacked in this order and placed in a vacuum press (manufactured by Mikado Technos Co., Ltd.), and subjected to pressure bonding treatment at 100 ° C. and 4 MPa for 10 minutes.

<Heat treatment 1>
The circuit board (B) in which the multilayer insulating film (C ′) was pressure-bonded and the through holes were filled with resin was subjected to a heat treatment at 120 ° C. for 10 minutes in a gear oven.

<Heat treatment 2>
Furthermore, heat treatment was performed at 170 ° C. for 60 minutes in a gear oven to obtain a circuit board (C).

<Etching>
The base copper foil on the circuit board (C) was etched while being rocked with ferric chloride at room temperature for 5 minutes to remove the copper foil and expose the first layer as the outermost surface. Then it was pure and well washed.

<Roughening plating>
Next, a roughening treatment was performed on the exposed surface of the first layer of the multilayer insulating film (C ′). A 70 ° C. potassium permanganate (concentrate compact CP, manufactured by Atotech Japan Co., Ltd.) roughened aqueous solution was placed in a multilayer insulating film and subjected to a swinging treatment for 5 minutes. In addition, the multi-layer insulating film after the permanganate treatment was treated for 2 minutes using a cleaning solution (Reduction Securigant P, manufactured by Atotech Japan Co., Ltd.) at 25 ° C., and then washed thoroughly and dried.
Next, the copper plating process was performed to the multilayer insulating film in which the roughened first layer became the outermost surface. The multilayer insulating film was treated with an alkali cleaner (cleaner securigant 902) at 60 ° C. for 5 minutes to degrease and clean the surface. After washing, the multilayer insulating film was treated with a 25 ° C. pre-dip solution (Pre-dip Neogant B) for 2 minutes. Thereafter, the multilayer insulating film was treated with an activator solution (activator Neogant 834) at 40 ° C. for 5 minutes to attach a palladium catalyst. Next, it was treated with a reducing solution (reducer Neogant WA) at 30 ° C. for 5 minutes. Next, the multilayer insulating film was placed in a chemical copper solution (basic print Gantt MSK-DK, copper print Gantt MSK, stabilizer print Gantt MSK), and electroless plating was performed until the plating thickness reached about 0.5 μm. After electroless plating, annealing was performed at a temperature of 120 ° C. for 30 minutes to remove residual hydrogen gas. In all the processes up to the electroless plating process, each process was performed while the processing liquid was 1 L on a beaker scale and the multilayer insulating film was swung.
Next, electrolytic plating was performed on the electroless plated resin sheet until the plating thickness reached 20 μm. Copper sulfate (reducer Cu) was used as the electrolytic copper plating, and the current was 0.6 A / cm ² . After baking at 180 ° C. × 1 hr was performed. Thereafter, it was thoroughly washed with pure water and thoroughly dried with a vacuum dryer.

[Examples 2 to 21 ( Examples 2, 3, 5 to 8, 10 to 13, 16 to 21 are reference examples) and Comparative Examples 1 to 5]:
The production of the circuit board, the multilayer, in the same manner as in Example 1, except that the raw material composition of the multilayer insulating film (C), the heating and drying conditions, the first layer gel fraction, etc. were as shown in Tables 1 to 4 below. Production of an insulating film, press treatment, and heat treatment were performed.
In addition, about the comparative example 3, the 1st layer of the multilayer insulating film was performed like Example 2, and the cured film (a) was obtained. Next, on a PET film (Toyobo Co., Ltd., thickness 35 μm, Ra: 70 nm, Rz: 1.2 μm) as a protective film, a resin composition comprising the raw material composition constituting the second layer of Example 2 was A cured film (b) was obtained by performing a heat treatment at 120 ° C. for 12 minutes in a heating and drying furnace after coating so that the film thickness was 120 μm. And the multilayer insulating film which consists of a base material, a 1st layer, a 2nd layer, and a protective film was obtained by bonding together the cured film (a) and the cured film (b) by 120 degreeC by vacuum lamination. Moreover, the press processing and heat processing similar to Example 2 were performed.

(Evaluation of Examples and Comparative Examples)
1. Embeddability The cross-section of the through-hole part of the circuit board (C) is observed with a metal microscope (OLYMPAS MM6-LS22). The multilayer insulation film (C) is sealed to the bottom. Was marked with x. Whether or not sealing was possible was determined based on the presence or absence of bubbles in the cross-section of the through-hole portion (the absence was marked with ◯ and the presence with x).

2. Roughening adhesive strength Since the example using a copper foil as a base material was difficult to measure because the copper foil was too thin, it was evaluated after plating after removing the copper foil.
The multilayer insulating film (C) is heated and laminated at 120 ° C. on a glass epoxy substrate (FR-4, product number “CS-3665”, manufactured by Risho Kogyo Co., Ltd.), and the base material is peeled off, and then in a 170 ° C. gear oven. The surface of the first layer was subjected to the following permanganate treatment, that is, roughening treatment.

(1) Permanganate treatment:
A 70 ° C. potassium permanganate (concentrate compact CP, manufactured by Atotech Japan Co., Ltd.) roughened aqueous solution was placed in a multilayer insulating film and subjected to a swinging treatment for 5 minutes. In addition, the multi-layer insulating film after the permanganate treatment was treated for 2 minutes using a cleaning solution (Reduction Securigant P, manufactured by Atotech Japan Co., Ltd.) at 25 ° C., and then washed thoroughly and dried.

(2) Copper plating treatment:
Next, the copper plating process was performed to the multilayer insulating film in which the roughened first layer became the outermost surface. The multilayer insulating film was treated with an alkali cleaner (cleaner securigant 902, manufactured by Atotech Japan) for 5 minutes, and the surface was degreased and washed. After washing, the multilayer insulating film was treated with a predip solution at 25 ° C. (Predip Neogant B, manufactured by Atotech Japan) for 2 minutes. Thereafter, the multilayer insulating film was treated with an activator solution at 40 ° C. (activator Neogant 834, manufactured by Atotech Japan) for 5 minutes to attach a palladium catalyst. Next, it was treated for 5 minutes with a 30 ° C. reducing solution (reducer Neogant WA, manufactured by Atotech Japan). Next, the multilayer insulation film is placed in a chemical copper solution (basic print Gantt MSK-DK, copper print Gantt MSK, stabilizer print Gantt MSK, all manufactured by Atotech Japan Co., Ltd.), and electroless plating is about 0.5 μm thick. It was carried out until. After electroless plating, annealing was performed at a temperature of 120 ° C. for 30 minutes to remove residual hydrogen gas. In all the processes up to the electroless plating process, each process was performed while the processing liquid was 1 L on a beaker scale and the multilayer insulating film was swung.
Next, electrolytic plating was performed on the electroless plated resin sheet until the plating thickness reached 20 μm. As the electrolytic copper plating, copper sulfate (reducer Cu, manufactured by Atotech Japan) was used, and the current was 0.6 A / cm ² . After baking at 180 ° C. × 1 hr was performed. The copper layer of the obtained cured product was notched into a width of 10 mm and measured under the condition of a crosshead speed of 5 mm / min to measure the roughened adhesive strength.
A specific method for measuring the roughened adhesive strength is to cut a 10 mm width notch into the obtained copper foil-plated circuit board, and use this tensile strength tester (trade name “Autograph”, Shimadzu Corporation). The copper layer is set on the chuck and measured using a tensile tester (trade name “Autograph”, manufactured by Shimadzu Corporation) under the condition of a crosshead speed of 5 mm / min. The adhesion strength between the insulated insulating resin layer and the copper plating was measured.

3. Surface Roughness A multilayer insulating film was pressure-pressed on a glass epoxy substrate (FR-4, product number “CS-3665”, manufactured by Risho Kogyo Co., Ltd.), and roughened with permanganate. The obtained cured product was measured for surface roughness (Ra, Rz) in a measuring range of 100 μm ² with a scanning laser microscope (product number “1LM21”, manufactured by Lasertec Corporation).

4). Insulating layer thickness Observe the cross section of any 50 circuit boards where no through-holes and vias exist, and from the upper surface side of the circuit board to which the multilayer insulating film (C) is bonded to the resin component of the multilayer insulating film. The distance to the top point was measured and the insulating layer thickness was calculated.
The insulating layer thickness is preferably 80% or more with respect to the original thickness of the first layer, and more preferably 90% or more of the original thickness.

5. Irregularities The cross section of the circuit board at any 50 locations in the through-hole part is observed, and the multilayer insulation film is determined from the distance from the upper surface of the circuit board to the uppermost point of the multilayer insulation film (C) in the vicinity of the through-hole. The average value of values obtained by subtracting the distance from the surface on the upper surface side of the circuit board to which (C) was pressure-bonded to the lowest point of the through-hole central portion was calculated as unevenness.
The unevenness is preferably 30% or less, more preferably 20% or less, with respect to the insulating layer thickness.

6). Variation in thickness Observe the cross-sections of any 50 circuit boards where there are no through-holes and vias. From the top surface of the circuit board to which the multilayer insulation film (C) is bonded to the resin component of the multilayer insulation film The distance to the point was measured, and the value obtained by subtracting the minimum value from the maximum value of these values was calculated as the variation.
The variation is preferably 40% or less, more preferably 30% or less with respect to the insulating layer thickness.

7). Peelability of first layer and second layer The cross section of the through-hole portion of the circuit board (C) is observed with a metal microscope (OLYMPAS MM6-LS22), and no peeling occurs at the interface between the first layer and the second layer. Observed whether or not.

8). Gel fraction of 1st layer The gel fraction of the cured film of the 1st layer produced in each Example and each comparative example was measured.
First, the cured film of the first layer was cut into a size of 50 mm × 50 mm, and the weight (Wo) was measured. Next, Examples 1-12 and Comparative Examples 1-10, which were cut out to a size of 50 mm × 50 mm in glass bottles filled with N, N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd.) at room temperature (23 ° C.). One layer of the cured film is immersed for 10 minutes, filtered through a metal mesh (No. 2000), the metal mesh and the residue on the metal mesh are heated and dried at 170 ° C. for 1 hour, and the weight (W1) at that time is It was measured. Then, the gel fraction (%) was calculated from the weight (Wo), the weight (W1), and the weight (Wc) of the metal mesh by the following formula.
Gel fraction (%) = {(W1) − (Wc)} / Wo × 100

  Moreover, said evaluation result is shown to following Tables 1-4 with a composition, manufacturing conditions, etc. of a multilayer insulation film.

  From the evaluation results of Tables 1 to 4, the multilayer insulating film obtained from the production method of the present invention can make the thicknesses of the first layer and the second layer uniform, such as a hole such as a through hole or a via hole. Even when a multilayer insulating film is laminated on a circuit board having irregularities, etc., voids are hardly generated, surface flatness is sufficiently secured, and the thickness of the first layer of the multilayer insulating film can be kept uniform. It was found that the first layer and the second layer were difficult to peel off. In addition, according to the method for producing a multilayer printed wiring board according to the present invention, even when a multilayer insulating film is laminated on a circuit board having via holes or other circuit pattern irregularities, the shrinkage rate due to the laminated portion of the multilayer insulating film Therefore, it is possible to obtain a multilayer printed wiring board composed of a circuit board and a multilayer insulating film in which the surface flatness of the multilayer insulating film is sufficiently ensured. Therefore, the multilayer printed wiring board using the multilayer insulating film according to the present invention as an insulating layer has an electrical resistance in the thickness direction and a length of an electrical signal when a circuit is formed on the circuit board using metal wiring. Variations are reduced and signal noise can be reduced.

  The method for producing a multilayer insulation film of the present invention is such that when a multilayer insulation film is laminated on a circuit board having irregularities such as through holes and via holes and circuit patterns, voids are not easily generated inside the board, and the surface is flat. Providing a method capable of producing a multilayer insulating film with sufficient productivity, capable of maintaining a uniform thickness of the first layer of the multilayer insulating film, and preventing the first layer and the second layer from being peeled off with high productivity, In addition, it is highly available.

Claims (7)

A method for producing a multilayer insulating film comprising a substrate (B) and an insulating layer (A) comprising a first layer (A1) and a second layer (A2) in contact with the substrate (B),
The insulating layer (A) is a resin composition comprising a thermosetting resin (a1), a curing agent (b1), an inorganic filler (c1), and a polymer material (d) containing a resin having a weight average molecular weight of 5000 or more ( I) , a resin composition (I) containing 5 to 60% by weight of the resin having a weight average molecular weight of 5000 or more based on the total amount of the composition (I) is formed into a film and immersed in dimethylformamide at room temperature for 10 minutes. gel fraction cured so that 72-94% of the time were, a first step of preparing a cured film of the first layer (AI), subsequently, the cured film, a thermosetting resin (a2) The second layer (A2) comprising the resin composition (II) containing 30 to 90% by weight of the inorganic filler (c2) based on the total solid content of the curing agent (b2) and the composition (II) is laminated. It is formed through two processes. A method for producing a multilayer insulating film.   2. The method for producing a multilayer insulating film according to claim 1, wherein a curing temperature in producing the cured film of the first layer (A1) is in the range of 130 to 150 ° C. 3.   The method for producing a multilayer insulating film according to claim 1, wherein the resin having a weight average molecular weight of 5000 or more contained in the polymer material (d) is a phenoxy resin.   The inorganic filler (c1) is silica that has been surface-treated with an imidazole silane coupling agent, and the silica is contained in an amount of 5 to 50% by weight based on the total solid content of the composition (I). The manufacturing method of the multilayer insulation film of Claim 1 characterized by the above-mentioned.   The inorganic filler (c2) contains silica and a layered silicate, and the layered silicate is 0.01 to 5% by weight based on the total solid content of the composition (II). 2. A method for producing a multilayer insulating film according to 1.   The method for producing a multilayer insulating film according to claim 1, wherein the thermosetting resin (a1, a2) is an epoxy resin, and the curing agent (b1, b2) is a phenol compound. The multilayer insulation film obtained from the method for producing a multilayer insulation film according to claim 1 is placed on the circuit board so that the second layer (A2) faces the circuit board, A first step of heating and pressurizing at a temperature of 60 to 200 ° C. and a pressure of 1 to 30 MPa;
A second step of heating the multilayer insulating film at a temperature of 60 to 140 ° C .;
A third step of heating the multilayer insulating film at a temperature in the range of 140 to 200 ° C. that is 20 ° C. higher than the temperature of the second step,
A method for producing a multilayer printed wiring board, comprising: