JPWO2011068157A1 - Resin composition for forming adhesive layer of multilayer flexible printed wiring board, resin varnish, copper foil with resin, method for producing copper foil with resin for multilayer flexible printed wiring board production - Google Patents

Abstract

An object of the present invention is to provide a resin composition that prevents so-called B-stage cracking, prevents powder falling off during the production process of a flexible printed wiring board, etc., and provides a good balance of performance such as folding resistance and heat resistance and resin flow To do. In order to solve the above-mentioned problems, in the resin composition used for forming an adhesive layer for multilayering the inner-layer flexible printed wiring board, component A: a solid high heat-resistant epoxy resin having a softening point of 50 ° C. or higher B component: biphenyl type phenol resin, epoxy resin curing agent composed of one or more of phenol aralkyl type phenol resin, C component: rubber-modified polyamide soluble in a solvent having a boiling point in the range of 50 ° C to 200 ° C An imide resin, D component: an organic phosphorus-containing flame retardant, E component: a resin composition characterized by containing a biphenyl type epoxy resin, and the like were employed.

Description

  The present invention relates to a resin composition for forming an adhesive layer of a multilayer flexible printed wiring board, a resin-coated copper foil having a resin layer formed of the resin varnish, a method for producing the resin-coated copper foil, and a multilayer flexible printed wiring board.

  A flexible printed wiring board having bendability is used as a printed wiring board used for supplying electronic signals of electronic devices. The flexible wiring board disclosed in Patent Document 1 has a structure in which an adhesive layer I, a conductor layer on which a circuit pattern is formed, an adhesive layer II, and a coverlay film are sequentially laminated on a base film. In the plate, an adhesive composition intended to obtain a sufficient bending life even when used at a high temperature is employed.

  As described above, the flexible printed wiring board is important for the bending resistance because of the product characteristics having the bendability. In addition, in the production of a flexible printed wiring board, heat is applied in a reflow process or the like, and therefore, folding resistance is required not to deteriorate even when used at a high temperature. Therefore, folding resistance and heat resistance are also desired for adhesives used for flexible printed wiring boards.

  In addition, demands for downsizing and high functionality of electronic devices are increasing, and miniaturization and multilayering are also being studied for flexible printed wiring boards in order to reduce the board size. And in order to multilayer a flexible printed wiring board, the characteristic more than a conventional product is requested | required also in the adhesive agent for flexible printed wiring boards. For example, in order to make a flexible printed wiring board multilayer, it is desired to realize heat resistance and folding resistance while thinning the adhesive layer. Further, when the flexible printed wiring board is multi-layered, it is necessary to improve the accuracy of interlayer connection.

  For such high-density mounting of flexible printed wiring boards, Patent Document 2 discloses a resin composition for the purpose of non-halogenation for flame resistance, flex resistance, and environmental friendliness.

JP 2006-70176 A JP 2005-248134 A

  Each of the resin compositions disclosed in Patent Document 1 and Patent Document 2 includes an inorganic filler (inorganic filler) for improving heat resistance, elastic modulus, flame retardancy, and the like. Therefore, when used as an adhesive for multilayer flexible printed wiring boards, there is a limit to the flexibility and the thinning of the adhesive layer. In addition, when forming a via hole for interlayer connection in a multilayer flexible printed wiring board, if an inorganic filler is included, the laser workability is lowered and the formation accuracy of the via hole is lowered. Furthermore, by punching the adhesive layer of the B stage, the adhesive layer is likely to fall off or crack. As a result, the adhesive layer powder adheres to the conductor layer, and the connection reliability is lowered. Moreover, when a crack arises in an adhesive bond layer, insulation performance will fall.

  Furthermore, as a result of verifying the adhesive composition disclosed in Patent Document 1, transfer of the inner layer circuit, undulation of the outermost layer, and voids are likely to occur during molding by laminating or pressing. When the transfer of the inner layer circuit occurs, the outermost layer swells, which causes troubles during resist application and circuit formation process. Furthermore, when voids are generated, the problem is that blisters are easily generated by heat treatment such as a reflow process.

  Therefore, the present invention prevents so-called B-stage cracking, prevents powder falling off during the production process of the flexible printed wiring board, etc., and also has a well-balanced and suitable range for performance such as folding resistance, heat resistance, and resin flow. An object of the present invention is to provide a resin composition for forming an adhesive layer of a multilayer flexible printed wiring board, a resin varnish, a resin-coated copper foil, a method for producing the resin-coated copper foil, and a multilayer flexible printed wiring board.

  As a result of intensive studies, the present inventors have achieved the above-mentioned problem by employing the following resin composition.

The resin composition for forming an adhesive layer of a multilayer flexible printed wiring board according to the present invention is a resin composition used for forming an adhesive layer for multilayering an inner flexible printed wiring board. Each component of the component is included.
A component: Solid high heat-resistant epoxy resin having a softening point of 50 ° C. or higher (excluding biphenyl type epoxy resin).
Component B: An epoxy resin curing agent comprising one or more of a biphenyl type phenol resin and a phenol aralkyl type phenol resin.
Component C: A rubber-modified polyamideimide resin soluble in a solvent having a boiling point in the range of 50 ° C to 200 ° C.
D component: An organic phosphorus-containing flame retardant.
E component: Biphenyl type epoxy resin.

  The resin varnish according to the present invention is a resin varnish prepared by adding a solvent to the resin composition described above and having a resin solid content in the range of 30 wt% to 70 wt%. According to MIL-P-13949G in the MIL standard, the resin flow when measured at a resin thickness of 55 μm is in the range of 0% to 10%.

  The resin-coated copper foil according to the present invention is a resin-coated copper foil provided with a resin layer on the surface of the copper foil, and the resin layer is formed using the above-described resin composition for forming an adhesive layer of a multilayer flexible printed wiring board. It is formed.

A method for producing a resin-coated copper foil for producing a multilayer flexible printed wiring board according to the present invention is a method for producing a resin-coated copper foil for producing the above-mentioned multilayer flexible printed wiring board, comprising the following steps a and b: The resin varnish used for forming the resin layer is prepared in the procedure, and the resin varnish is applied to the surface of the copper foil and dried to form a copper foil with resin as a semi-cured resin layer having a thickness of 10 μm to 80 μm. Features.
Step a: When the weight of the resin composition is 100 parts by weight, the A component is 3 to 30 parts by weight, the B component is 13 to 35 parts by weight, the C component is 10 to 50 parts by weight, and the D component Is a resin composition containing each component in the range of 3 to 16 parts by weight and E component in the range of 5 to 35 parts by weight.
Process b: The said resin composition is melt | dissolved using an organic solvent, and it is set as the resin varnish whose resin solid content amount is 30 weight%-70 weight%.

  The multilayer flexible printed wiring board according to the present invention is obtained using a resin composition for forming an adhesive layer of a multilayer flexible printed wiring board.

  The resin composition according to the present invention can prevent a decrease in folding resistance due to thermal degradation, and can improve cracking at the B stage. In addition, the resin-coated copper foil obtained using the resin composition according to the present invention does not require an inorganic filler when used as a constituent material of a flexible printed wiring board, and thus has excellent flexibility and a laser. Processing and punching can be performed with high accuracy, and occurrence of powder falling and cracking can be prevented. Furthermore, since the resin-coated copper foil according to the present invention does not contain an inorganic filler, it is suitable for forming a via hole in a multilayer flexible printed wiring board and can improve the reliability of interlayer connection.

  Hereinafter, preferred embodiments of the present invention will be described.

Resin composition: The resin composition according to the present invention is used to form an adhesive layer for multilayering an inner flexible printed wiring board. And each component of the following A component-E component is included, It is characterized by the above-mentioned.

A component: Solid high heat-resistant epoxy resin having a softening point of 50 ° C. or higher (excluding biphenyl type epoxy resin).
Component B: An epoxy resin curing agent comprising one or more of a biphenyl type phenol resin and a phenol aralkyl type phenol resin.
Component C: A rubber-modified polyamideimide resin soluble in a solvent having a boiling point in the range of 50 ° C to 200 ° C.
D component: An organic phosphorus-containing flame retardant.
E component: Biphenyl type epoxy resin.

  The component A is a solid high heat resistant epoxy resin having a softening point of 50 ° C. or higher. The component A is an epoxy resin having a high so-called glass transition temperature Tg. The reason why a solid high heat resistant epoxy resin having a softening point of 50 ° C. or higher among the epoxy resins is used is that the glass transition temperature Tg is high, and a high heat resistance effect can be obtained by adding a small amount.

  The “solid high heat resistant epoxy resin having a softening point of 50 ° C. or higher” mentioned here is one or more of cresol novolac type epoxy resin, phenol novolac type epoxy resin, and naphthalene type epoxy resin. It is preferable.

  In addition to the solid high heat-resistant epoxy resin having a softening point of 50 ° C. or higher, the component A further includes a novolac type epoxy resin, a cresol novolac type epoxy resin, a phenol novolak type epoxy resin, and a naphthalene type. It is good also as what contains the highly heat-resistant epoxy resin which consists of any 1 type or 2 types or more of an epoxy resin. As described above, as the component A, a high heat-resistant epoxy composed of one or more of a novolak type epoxy resin, a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, and a naphthalene type epoxy resin that is liquid at room temperature. If the resin is contained, the effect of further improving the glass transition temperature Tg and improving the B stage cracking can be enhanced.

  The component A is preferably used in the range of 3 to 30 parts by weight when the resin composition is 100 parts by weight. When the component A is less than 3 parts by weight, it is difficult to increase the Tg of the resin composition. On the other hand, when the component A exceeds 30 parts by weight, the cured resin layer becomes brittle and the flexibility is completely impaired, which is not preferable for use as a flexible printed wiring board. More preferably, the component A is used in the range of 10 to 25 parts by weight, so that both high Tg of the resin composition and good flexibility of the resin layer after curing can be stably achieved.

  Component B is an epoxy resin curing agent composed of one or more of a biphenyl type phenol resin and a phenol aralkyl type phenol resin. The addition amount of the epoxy resin curing agent is naturally derived from the reaction equivalent to the resin to be cured, and does not require any particular quantitative limitation. However, in the case of the resin composition according to the present invention, the component B is preferably used in the range of 13 parts by weight to 35 parts by weight when the resin composition is 100 parts by weight. When this B component is less than 13 parts by weight, considering the resin composition of the present invention, it becomes impossible to obtain a sufficiently cured state, and it becomes impossible to obtain the flexibility of the cured resin layer. On the other hand, when the component B exceeds 35 parts by weight, the moisture absorption resistance of the cured resin layer tends to deteriorate, which is not preferable.

  A specific example of the biphenyl type phenol resin is shown in Chemical Formula 1.

  A specific example of the phenol aralkyl type phenol resin is shown in Chemical Formula 2.

  Component C is a rubber-modified polyamideimide resin that is soluble in a solvent having a boiling point in the range of 50 ° C to 200 ° C. By mix | blending the said C component, while improving a flexible performance, the effect which suppresses a resin flow is acquired. This rubber-modified polyamideimide resin is obtained by reacting a polyamideimide resin and a rubber resin, and is performed for the purpose of improving the flexibility of the polyamideimide resin itself. That is, the polyamideimide resin and the rubber resin are reacted to replace a part of the acid component (cyclohexanedicarboxylic acid or the like) of the polyamideimide resin with the rubber component. The rubber component is described as a concept including natural rubber and synthetic rubber. Examples of the latter synthetic rubber include styrene-butadiene rubber, butadiene rubber, butyl rubber, ethylene-propylene rubber, and acrylonitrile butadiene rubber. Furthermore, from the viewpoint of ensuring heat resistance, it is also useful to selectively use a synthetic rubber having heat resistance such as nitrile rubber, chloroprene rubber, silicon rubber, urethane rubber and the like. Since these rubber-like resins react with the polyamide-imide resin to produce a copolymer, it is desirable to have various functional groups at both ends. In particular, it is useful to use CTBN (carboxy group-terminated butadiene nitrile rubber) having a carboxyl group. In addition, the said rubber component may copolymerize only 1 type or may copolymerize 2 or more types. Further, when a rubber component is used, it is preferable to use a rubber component having a number average molecular weight of 1000 or more from the viewpoint of stabilization of flexibility.

  When polymerizing the rubber-modified polyamideimide resin, the solvents used for dissolving the polyamideimide resin and the rubbery resin include dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, nitromethane, nitroethane, and tetrahydrofuran. , Cyclohexanone, methyl ethyl ketone, acetonitrile, γ-butyrolactone, and the like are preferably used alone or in combination. And in order to raise | generate a polymerization reaction, it is preferable to employ | adopt the polymerization temperature of the range of 80 to 200 degreeC. When a solvent having a boiling point of more than 200 ° C. is used for these polymerizations, it is preferable that the solvent be replaced with a solvent having a boiling point in the range of 50 ° C. to 200 ° C., depending on the application.

  Here, examples of the solvent having a boiling point in the range of 50 ° C. to 200 ° C. include one single solvent or two or more mixed solvents selected from the group of methyl ethyl ketone, dimethylacetamide, dimethylformamide and the like. When the boiling point is lower than 50 ° C., the solvent is greatly diffused by heating, and it is difficult to obtain a good semi-cured state when the resin varnish is changed to a semi-cured resin. On the other hand, when the boiling point exceeds 200 ° C., when the semi-cured resin is used from the state of the resin varnish, it is difficult to obtain a good semi-cured resin layer because the solvent is difficult to dry.

  Among the rubber-modified polyamideimide resins used in the resin composition according to the present invention, when the weight of the rubber-modified polyamideimide resin is 100% by weight, the copolymerization amount of the rubber component may be 0.8% by weight or more. preferable. When the copolymerization amount is less than 0.8% by weight, the rubber-modified polyamide-imide resin lacks flexibility when the resin layer formed using the resin composition according to the present invention is cured, Since the adhesiveness with copper foil also falls, it is not preferable. More preferably, the copolymerization amount of the rubber component is 3% by weight or more, more preferably 5% by weight or more. Empirically, there is no particular problem even if the copolymerization amount exceeds 40% by weight. However, since the effect of improving the flexibility of the cured resin layer is saturated, resources are wasted, which is not preferable.

  The rubber-modified polyamide-imide resin described above is required to be soluble in a solvent. This is because preparation as a resin varnish is difficult unless it is soluble in a solvent. The rubber-modified polyamide-imide resin is used in a blending ratio of 10 to 50 parts by weight when the weight of the resin composition is 100 parts by weight. When the rubber-modified polyamideimide resin is less than 10 parts by weight, the resin flow suppressing effect is hardly exhibited. In addition, the cured resin layer becomes brittle and it is difficult to improve flexibility. As a result, there is an effect that microcracks of the resin layer are likely to occur. On the other hand, when the rubber-modified polyamide-imide resin is added in an amount exceeding 50 parts by weight, the embedding property in the inner layer circuit is lowered, and as a result, voids are easily generated, which is not preferable.

  Component D is an organic phosphorus-containing flame retardant and is used to improve flame retardancy. Examples of organic phosphorus-containing flame retardants include phosphorus-containing flame retardants composed of phosphate esters and / or phosphazene compounds. The component D is preferably used in the range of 3 to 16 parts by weight when the resin composition is 100 parts by weight. When the content of the D component is less than 3 parts by weight, the flame retardancy effect cannot be obtained. On the other hand, even if the content of the D component exceeds 16 parts by weight, improvement in flame retardancy cannot be expected. In addition, more preferable content of D component is 5 weight part-14 weight part.

  In addition, when the resin composition according to the present invention is added so that the total content of phosphorus is in the range of 0.5 wt% to 5 wt% when the weight of the resin composition is 100 wt%, it is flame retardant. Is preferable.

  The E component is a biphenyl type epoxy resin. The biphenyl type epoxy resin contributes to improvement of so-called glass transition temperature Tg and flexibility. Examples of the biphenyl type epoxy resin include a biphenyl aralkyl type epoxy resin. The component E is preferably used in the range of 5 to 35 parts by weight when the resin composition is 100 parts by weight. When the content of the E component is less than 5 parts by weight, the effect of increasing the glass transition temperature Tg and the flexibility cannot be obtained. On the other hand, even if the content of the E component exceeds 35 parts by weight, it is not possible to expect a high Tg and an improvement in flexibility. In addition, more preferable content of E component is 7 weight part-25 weight part.

  In addition to the A component to the E component, if the resin composition includes a phosphorus-containing flame-retardant epoxy resin as the F component, the flame retardancy can be further improved. The phosphorus-containing flame-retardant epoxy resin is a general term for epoxy resins containing phosphorus in an epoxy skeleton, and is a so-called halogen-free flame-retardant epoxy resin. And phosphorus content which can make phosphorus atom derived from F component into the range of 0.1 weight%-5 weight% when the resin composition weight is 100 weight% about the phosphorus atom content of the resin composition concerning this application Any flame retardant epoxy resin can be used. However, using a phosphorus-containing flame retardant epoxy resin having two or more epoxy groups in the molecule, which is a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivative, is a semi-cured state. It is preferable because it has excellent resin quality stability at the same time and has a high flame retardant effect. For reference, the structural formula of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is shown in Chemical Formula 3.

  This 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivative, a phosphorus-containing flame-retardant epoxy resin having two or more epoxy groups in the molecule, is 9,10-dihydro-9. -Oxa-10-phosphaphenanthrene-10-oxide is reacted with naphthoquinone or hydroquinone to form a compound shown in the following chemical formula 4 or chemical formula 5, and then the epoxy resin is reacted with the OH group portion to make it difficult to contain phosphorus. What was made into the flammable epoxy resin is preferable.

  A specific example of a phosphorus-containing flame-retardant epoxy resin having two or more epoxy groups in the molecule, which is a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivative, The use of a compound having the structural formula shown in Chemical Formula 6, Chemical Formula 7 or Chemical Formula 8 is preferred.

  Here, when the phosphorus-containing flame-retardant epoxy resin is used, the resin composition may be one of the phosphorus-containing flame-retardant epoxy resins as the F component, or two or more phosphorus-containing flame-retardant epoxy resins. May be used in combination. However, considering the total amount of the phosphorus-containing flame-retardant epoxy resin as the F component, when the resin composition weight is 100% by weight, the phosphorus atom derived from the F component is in the range of 0.1% to 5% by weight. It is preferable to add so that it becomes. The phosphorus-containing flame-retardant epoxy resin has different amounts of phosphorus atoms contained in the epoxy skeleton depending on the type. Therefore, it is possible to define the content of phosphorus atoms as described above and replace it with the addition amount of the F component. However, the component F is usually used in the range of 5 to 50 parts by weight when the resin composition is 100 parts by weight. In the case where the F component is less than 5 parts by weight, it becomes difficult to make the phosphorus atom derived from the F component 0.1% by weight or more in consideration of the blending ratio of the other resin components. Can not get. On the other hand, even if the F component exceeds 50 parts by weight, the effect of improving flame retardancy is saturated, and at the same time, the cured resin layer becomes brittle.

  “High Tg” and “flexibility” of the cured resin layer described above are generally inversely proportional characteristics. At this time, there are phosphorus-containing flame-retardant epoxy resins that contribute to improving the flexibility of the cured resin layer and those that contribute to high Tg. Therefore, rather than using one type of phosphorus-containing flame-retardant epoxy resin, “phosphorus-containing flame-retardant epoxy resin that contributes to higher Tg” and “phosphorus-containing flame-retardant epoxy resin that contributes to improved flexibility” By mixing and using in a well-balanced manner, it is possible to obtain a resin composition suitable for flexible printed wiring board applications.

  The resin composition according to the present invention is further selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol AD type epoxy resin having an epoxy equivalent of 200 or less and being liquid at room temperature as the G component. Or it is good also as what contains the epoxy resin which consists of 2 or more types. Here, the reason why the bisphenol-based epoxy resin is selectively used is that the compatibility with the component C (rubber-modified polyamideimide resin) is good, and it is easy to impart appropriate flexibility to the semi-cured resin layer. If the epoxy equivalent exceeds 200, the resin becomes semi-solid at room temperature, and the flexibility in the semi-cured state decreases, which is not preferable. Furthermore, if it is the above-mentioned bisphenol-type epoxy resin, 1 type may be used independently or 2 or more types may be used in mixture. In addition, when two or more kinds are mixed and used, there is no particular limitation with respect to the mixing ratio.

  This G component epoxy resin, when the resin composition is 100 parts by weight, exhibits a sufficient thermosetting property when used in a blending ratio of 2 to 15 parts by weight. It is preferable because the occurrence of a so-called warp phenomenon can be reduced, and the flexibility of the resin layer in a semi-cured state can be further improved. When the said epoxy resin exceeds 15 weight part, there exists a tendency for a flame retardance to fall from the balance with another resin component, or for the resin layer after hardening to become hard. Moreover, considering the amount of component C (rubber-modified polyamideimide resin) added, sufficient toughness for the cured resin layer cannot be obtained.

  The resin composition according to the present invention may further include a low-elasticity substance made of a thermoplastic resin and / or a synthetic rubber as the H component. By setting it as the resin composition containing H component, the crack in the semi-hardened state of a resin composition can be prevented, and the flexibility after hardening can be improved. Examples of the low-elasticity material as the H component include acrylonitrile butadiene rubber, acrylic rubber (acrylic ester copolymer), polybutadiene rubber, isoprene, hydrogenated polybutadiene, polyvinyl butyral, polyethersulfone, phenoxy, and polymer epoxy. And aromatic polyamides. One of these may be used alone, or two or more may be used in combination. In particular, acrylonitrile butadiene rubber is preferably used. Among the acrylonitrile butadiene rubbers, a carboxyl-modified product can take a crosslinked structure with an epoxy resin and improve the flexibility of the cured resin layer. As the carboxyl-modified product, it is preferable to use carboxy group-terminated nitrile butadiene rubber (CTBN), carboxy group-terminated butadiene rubber (CTB), or carboxy-modified nitrile butadiene rubber (C-NBR).

  The H component is preferably used at a blending ratio of 25 parts by weight or less when the resin composition is 100 parts by weight. If an H component in an amount exceeding 25 parts by weight is added, problems such as a decrease in glass transition temperature Tg, a decrease in solder heat resistance, a decrease in peel strength, and an increase in thermal expansion coefficient are undesirable.

  The resin composition according to the present invention can improve the flame retardancy and the glass transition temperature Tg by combining the above-described components A to E, and can prevent the heat resistance of the folding resistance. And sufficient flexibility can be obtained, without adding an inorganic filler like the conventional resin composition for adhesive agents. Furthermore, it is possible to prevent cracking in a semi-cured state and powder falling off during punching.

Resin varnish according to the present invention: The resin varnish according to the present invention is prepared by adding a solvent to the above resin composition so that the resin solid content is in the range of 30 wt% to 70 wt%. The semi-cured resin layer formed with this resin varnish has a resin flow in the range of 0% to 10% when measured with a resin thickness of 55 μm according to MIL-P-13949G in the MIL standard. Features. As the solvent mentioned here, one kind of single solvent selected from the group of methyl ethyl ketone, dimethylacetamide, dimethylformamide, etc., which is a solvent having a boiling point in the range of 50 ° C. to 200 ° C., or a mixed solvent of two or more kinds is used. It is preferable. This is for obtaining a good semi-cured resin layer as described above. And the range of the resin solid content shown here is a range in which the film thickness can be controlled to the most accurate one when applied to the surface of the copper foil. When the resin solid content is less than 30% by weight, the viscosity is too low and it flows immediately after application to the copper foil surface, making it difficult to ensure film thickness uniformity. On the other hand, when the resin solid content exceeds 70% by weight, the viscosity increases and it becomes difficult to form a thin film on the surface of the copper foil.

  When the resin varnish is used to form a semi-cured resin layer, the measured resin flow is preferably in the range of 0% to 10%. When the resin flow is high, the thickness of the insulating layer formed using the resin layer of the resin-coated copper foil becomes nonuniform. However, the resin varnish according to the present invention can suppress the resin flow to a low value of 10% or less. In addition, since the resin varnish which concerns on this invention can implement | achieve the level which resin flow hardly produces, the lower limit of the said resin flow was made into 0%. In addition, the more preferable range of the resin flow of the resin varnish concerning this invention is 0%-5%.

In this specification, the resin flow is based on MIL-P-13949G in the MIL standard. Four 10 cm square samples are sampled from a resin-coated copper foil with a resin thickness of 55 μm. It is a value calculated based on Equation 1 from the result of measuring the resin outflow weight at the time of laminating under the conditions of a press temperature of 171 ° C., a press pressure of 14 kgf / cm ² , and a press time of 10 minutes in a stacked state (laminate) .

Resin-coated copper foil according to the present invention: The resin-coated copper foil according to the present invention is a resin-coated copper foil for producing a multilayer flexible printed wiring board having a resin layer on the surface of the copper foil. And in the said copper foil with resin, the resin layer was formed using the resin composition for contact bonding layer formation of the above-mentioned multilayer flexible printed wiring board, It is characterized by the above-mentioned.

  Here, the copper foil is not particularly limited, and the thickness is not particularly limited. Moreover, the manufacturing method of copper foil is not restricted, and what was obtained by all the manufacturing methods, such as an electrolytic method or a rolling method, can be used. Further, the surface on which the resin layer of the copper foil is formed may or may not be roughened. If there exists a roughening process, the adhesiveness of copper foil and a resin layer will improve. And if it does not perform a roughening process, since it will become a flat surface, the formation capability of a fine pitch circuit will improve. Furthermore, the surface of the copper foil may be subjected to rust prevention treatment. Regarding the rust prevention treatment, it is possible to employ inorganic rust prevention using known zinc, zinc-based alloys, or the like, or organic rust prevention using an organic monomolecular film such as benzimidazole or triazole. Furthermore, it is preferable to provide a silane coupling agent treatment layer on the surface on which the resin layer of the copper foil is formed.

  The silane coupling agent layer plays a role as an auxiliary agent for improving the wettability between the surface of the copper foil not particularly roughened and the resin layer and improving the adhesion. For example, without roughening copper foil, rust prevention treatment is applied, and silane coupling agent treatment is epoxy functional silane coupling agent, olefin functional silane, acrylic functional silane, amino functional silane coupling Various agents such as an agent or a mercapto-functional silane coupling agent can be used, and the peel strength exceeds 0.8 kgf / cm by selecting and using a suitable silane coupling agent according to the application become.

  The silane coupling agent that can be used here will be described more specifically. Vinyl trimethoxy silane, vinyl phenyl trimethoxy lane, γ-methacryloxypropyl trimethoxy silane, γ-glycidoxy propyl trimethoxy silane mainly used for the same coupling agent as used for glass cloth of prepreg for printed wiring board, 4-glycidylbutyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-3- (4- (3-aminopropoxy) ptoxy) propyl-3- Aminopropyltrimethoxysilane, imidazolesilane, triazinesilane, γ-mercaptopropyltrimethoxysilane and the like can be used.

  The formation of the silane coupling agent layer is not particularly limited, such as a commonly used dipping method, showering method, spraying method, or the like. In accordance with the process design, a method that can contact and adsorb the solution containing the copper foil and the silane coupling agent most uniformly can be arbitrarily employed. These silane coupling agents are used at a room temperature level by dissolving 0.5 to 10 g / l in water as a solvent. Since the silane coupling agent forms a film by condensation bonding with OH groups protruding on the surface of the copper foil, the effect is not significantly increased even if a solution having a very high concentration is used. Therefore, it should be originally determined according to the processing speed of the process. However, if it is less than 0.5 g / l, the adsorption rate of the silane coupling agent is slow, which is not suitable for general commercial profit, and the adsorption is not uniform. Moreover, even if the concentration exceeds 10 g / l, the adsorption rate is not particularly increased, which is uneconomical.

  The copper foil with resin described above is one kind of polyimide resin, polyamide resin, polyether sulfone resin, phenoxy resin, aramid resin, polyvinyl acetal resin between the copper foil to be used and the semi-cured resin layer. It is also possible to form an auxiliary resin layer made of two or more kinds of mixed resins. This auxiliary resin layer is formed before the semi-cured resin layer is formed. By adopting such a two-layer structure of an auxiliary resin layer and a semi-cured resin layer, it is possible to further improve the flexibility as a resin-coated copper foil and to be suitable for flexible printed wiring board applications. it can. These auxiliary resin layers can be formed by a method generally called a casting method. More specifically, a resin varnish for forming either a polyimide resin, a polyamide resin, or a mixed resin of these two types is applied to the copper foil surface, a part of the solvent is removed by a drying process, and the temperature is further increased. It can be formed by removing the solvent and / or dehydrating condensation reaction in the drying step. At this time, the thickness of the auxiliary resin layer is desirably 10 μm or less. If it exceeds 10 μm, the total thickness will increase when combined with the semi-cured resin layer referred to in the present invention, so it is difficult to reduce the total thickness when processed into a flexible printed wiring board. At the same time, the curling phenomenon is likely to occur in the resin-coated copper foil due to heating when forming the semi-cured resin layer, which is not preferable.

Manufacturing method of resin-coated copper foil according to the present invention: The manufacturing method of the resin-coated copper foil according to the present invention is a manufacturing method of the resin-coated copper foil for manufacturing the multilayer flexible printed wiring board, comprising the following steps a, A resin varnish used for forming a resin layer is prepared in the procedure of step b, and the resin varnish is applied to the surface of the copper foil and dried to form a semi-cured resin layer having a thickness of 10 μm to 80 μm and a resin-coated copper foil It is characterized by doing. Here, when the thickness of the semi-cured resin layer is less than 10 μm, the adhesion with the inner-layer flexible printed wiring board tends to vary.

Step a: When the weight of the resin composition is 100 parts by weight, the A component is 3 to 30 parts by weight, the B component is 13 to 35 parts by weight, the C component is 10 to 50 parts by weight, and the D component Is a resin composition containing each component in the range of 3 to 16 parts by weight and E component in the range of 5 to 35 parts by weight. Since the description about each component and the mixture ratio described here is as above-mentioned, description here is abbreviate | omitted. There are no particular limitations on the order of mixing these components, the mixing temperature, the mixing procedure, the mixing apparatus, and the like.

Step b: The resin composition is dissolved using an organic solvent to obtain a resin varnish. The organic solvent at this time is a solvent having a boiling point in the range of 50 ° C. to 200 ° C. as described above, one single solvent selected from the group such as methyl ethyl ketone, dimethylacetamide, dimethylformamide, or two or more types. It is preferable to use a mixed solvent. This is because of the same reason as described above. And let resin solid content be 30 to 70 weight% resin varnish here. The reason for determining the range of the resin solid content is the same as described above. In addition, it is not impossible to use any solvent other than those specifically mentioned here as long as it can dissolve all the resin components used in the present invention.

  When the resin varnish obtained as described above is applied to one side of a copper foil, the application method is not particularly limited. However, considering that the target thickness must be applied with high accuracy, a coating method and a coating apparatus corresponding to the film thickness to be formed may be appropriately selected and used. Moreover, what is necessary is just to employ | adopt suitably the heating conditions which can be made into a semi-hardened state according to the property of the resin solution for the drying after forming the resin film on the surface of copper foil.

Multilayer flexible printed wiring board according to the present invention: The multilayer flexible printed wiring board according to the present invention is obtained by using the above-described resin composition for forming an adhesive layer of a multilayer flexible printed wiring board. . That is, using the resin composition according to the present invention as a resin varnish, a resin-coated copper foil is produced using the resin varnish. And it is set as the multilayer flexible printed wiring board using this copper foil with resin. At this time, there is no special limitation regarding a manufacturing process until it is set as a multilayer flexible printed wiring board using copper foil with resin. Any known manufacturing technique can be used. In addition, the multilayer flexible printed wiring board said to this invention says what is provided with the conductor layer containing the circuit shape of three or more layers. Examples are shown below.

  The resin components used in Examples and Comparative Examples are shown below. Examples of synthesis of the C component rubber-modified polyamideimide resin and the F component phosphorus-containing flame-retardant epoxy resin will be described later.

A component: Solid high heat resistant epoxy resin (cresol novolac type epoxy resin YDCN-704, softening point 90 ° C. manufactured by Toto Kasei Co., Ltd.),
Liquid heat-resistant epoxy resin (Naphthalene type epoxy resin DIC Corporation HP4032-D)
Component B: epoxy resin curing agent (biphenyl type phenolic resin, Meiwa Kasei Co., Ltd., MEH-7851M)
Component C: Rubber-modified polyamideimide resin Component D: Phosphorus-containing flame retardant (aromatic condensed phosphate ester PX-200, manufactured by Daihachi Chemical Co., Ltd.)
E component: biphenyl type epoxy resin (NC-3000 manufactured by Nippon Kayaku Co., Ltd.)
F component: phosphorus-containing flame-retardant epoxy resin G component: bisphenol A type liquid epoxy resin (Epiclon 850S manufactured by DIC Corporation)
H component: low elasticity substance (acrylonitrile butadiene rubber JSR Co., Ltd. PNR-1H)

Preparation of component C rubber-modified polyamideimide resin: Here, the method described in JP-A No. 2004-152675 was adopted, and trimellitic acid was added to a four-necked flask equipped with a thermometer, a cooling pipe, and a nitrogen gas introduction pipe. 0.9 mol of anhydride (TMA), 0.1 mol of dicarboxypoly (acrylonitrile-butadiene) rubber (Hiker CTBN 1300 × 13: molecular weight 3500, manufactured by Ube Industries), 1 mol of diphenylmethane diisocyanate (MDI), 0. 01 mol was charged with N-methyl-2-pyrrolidone so that the solid content concentration would be 20%, stirred at 120 ° C. for 1.5 hours, then heated to 180 ° C. and further stirred for about 3 hours to modify the amount of rubber modification A 9% by weight polyamideimide resin was synthesized. The obtained polyamidoimide resin had a logarithmic viscosity of 0.65 dl / g and a glass transition temperature of 160 ° C.

  Next, a synthesis example of a phosphorus-containing flame-retardant epoxy resin as the F component will be described.

Synthesis example of phosphorus-containing flame-retardant epoxy resin: 10- (2,5-dihydroxyphenyl) -10H was added to a four-necked glass separable flask equipped with a stirrer, thermometer, condenser, and nitrogen gas introducing device. 324 parts by weight of -9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA-HQ) and 300 parts by weight of ethyl cellosolve were charged and dissolved by heating. 680 parts by weight of YDF-170 (Bisphenol F type epoxy resin manufactured by Toto Kasei Co., Ltd.) was charged, stirred while introducing nitrogen gas, heated to 120 ° C. and mixed. 0.3 parts by weight of a triphenylphosphine reagent was added and reacted at 160 ° C. for 4 hours. The epoxy equivalent of the obtained epoxy resin was 501 g / eq, and the phosphorus content was 3.1% by weight.

[Example 1]
Example 1 uses a phosphorus-containing flame-retardant epoxy resin, a rubber-modified polyamide-imide resin, and the like obtained by the synthesis method described above, and a resin composition having a blending ratio shown in Table 1, and further uses dimethyl as a solvent. A resin varnish was prepared using a mixed solvent mixed at a ratio of acetamide: methyl ethyl ketone = 3: 2 (weight ratio).

  The resin varnish was applied to a roughened surface of a commercially available electrolytic copper foil (18 μm thick) using an edge coater so that the thickness after drying was 50 μm, and the heating conditions were 150 ° C. for 3 minutes. Then, the solvent was diffused to obtain a resin-coated copper foil. Using this resin-coated copper foil, the glass transition temperature Tg, the flexibility evaluation of the cured resin layer, and the punching performance were evaluated. Moreover, the multilayer printed wiring board was produced using this resin-coated copper foil, and peel strength and normal solder heat resistance test, boiling solder heat resistance test, and moisture absorption solder heat resistance test were performed. Further, a resin-coated copper foil provided with a resin layer having a thickness of 55 μm was prepared by the same method as that for the resin-coated copper foil, and the resin flow was evaluated. These evaluations and test results are summarized in Table 2.

[Flexibility evaluation after curing of resin layer]
Here, the resin-coated copper foil was vacuum-pressed for 90 minutes at a heating temperature of 190 ° C. and a pressing pressure of 40 kgf / cm ² , and the copper foil was removed by etching to produce a resin film having a thickness of 46 μm. And this resin film was cut out to 30 mm x 5 mm, and it was set as the bending resistance test film. And the bending resistance test by MIT method was done using this bending resistance test film. The bending resistance test by the MIT method uses a film folding fatigue tester with a tank (product number: 549) manufactured by Toyo Seiki Seisakusho as an MIT folding resistance device, with a bending radius of 0.8 mm and a load of 0.5 kgf. A repeated bending test of the bending resistance test film was performed. In Table 2 which shows the result, the bending resistance test film which was able to measure the number of repeated bendings of 2000 times or more was evaluated as acceptable. In addition, the number of repeated bendings was measured with one reciprocation of the driving head of the MIT folding apparatus as one time (one cycle).

[Resin flow]
According to the above-mentioned conditions, the resin flow of a resin-coated copper foil having a resin thickness of 55 μm was measured. Furthermore, the resin flow was evaluated. First, the B-staged resin-coated copper foil was punched from the copper surface side with a punch, and then vacuum-pressed for 90 minutes at a heating temperature of 190 ° C. and a pressing pressure of 40 kgf / cm ² . Then, the punched part was observed after pressing, and the resin flow was evaluated by examining the protrusion of the resin from the punched part of the punched part by pressing. Here, the case where the protrusion of the resin from the punched portion of the punch was 200 μm or less was determined to be acceptable. The evaluation results are shown in Table 2.

[Punching performance]
The punching performance of B-stage resin-coated copper foil is as follows: B-stage resin-coated copper foil is placed with the copper foil surface facing up, and punched from the bottom surface (resin surface) to the top surface (copper foil surface) with a punch. Processing was performed. When punching with a punch, if the resin powder is generated as x rejected, no resin powder is produced, but if the B stage resin is cracked, pass B, and if the B stage resin is neither resin powder nor cracked Evaluated as excellent ◎. The evaluation results are shown in Table 2.

[Measurement of glass transition temperature Tg]
The resin-coated copper foil produced as described above was vacuum-pressed for 90 minutes at a heating temperature of 190 ° C. and a pressing pressure of 40 kgf / cm ² , and the copper foil was removed by etching to obtain a resin film having a thickness of 46 μm. Produced. And this resin film was cut out to 30 mm x 5 mm, and the glass transition temperature Tg was measured. The glass transition temperature Tg was measured using a dynamic viscoelasticity measuring device (product number: SDM5600) manufactured by Seiko Denshi Kogyo Co., Ltd. as a dynamic viscoelasticity measuring device (DMA). The results are shown in Table 2 below.

[Evaluation using multilayer printed wiring board]
Peeling strength and normal solder heat resistance test: Both sides of a commercially available 0.4 mm thick FR-4 (glass-epoxy substrate) on both sides of a copper clad laminate laminated with 18 μm thick electrolytic copper foil Then, an inner layer circuit was formed, and a blackening process was performed to produce an inner layer core material. Next, the resin-coated copper foil is laminated on both surfaces of the inner layer core material under a vacuum pressing condition of a heating temperature of 190 ° C. and a pressing pressure of 40 kgf / cm ² for 90 minutes to obtain a four-layer multilayer printed wiring board. It was. Then, using this multilayer printed wiring board, a 10 mm width peeling test linear circuit was formed, and this was peeled off in the direction of 90 ° with respect to the substrate surface, and the “stripping strength” was measured. In addition, a solder heat resistance measurement sample cut out from a four-layer multilayer printed wiring board to a size of 50 mm × 50 mm was floated in a 260 ° C. solder bath, and “normal solder heat resistance” was measured as the time until blistering occurred. . The peel strength was indicated as “◯” when exceeding 1.0 kgf / cm and “x” when less than 1.0 kgf / cm. In addition, the normal solder heat resistance was evaluated as “◯” when 300 seconds or more and “x” when less than 300 seconds. The evaluation results are shown in Table 2.

Boiled solder heat resistance test: After removing the copper foil layer of the outer layer of the solder heat resistance measurement sample cut out to the size of 50 mm × 50 mm from the four-layer multilayer printed wiring board described above, it was immersed in boiling ion exchange water. Then, a boiling treatment for 3 hours was performed. And from the sample which boiled, the water | moisture content was fully removed immediately, and it immersed in the solder bath of 260 degreeC for 20 second, and the presence or absence of blistering was confirmed. Evaluation was made with ○ indicating no blistering and × indicating that blistering was visually confirmed. The results are shown in Table 2.

Moisture-absorbing solder heat resistance test: In the production of the above-described four-layer multilayer printed wiring board, the resin-coated copper foil was held for 15 hours in a constant temperature and humidity chamber with a temperature of 30 ° C. and a relative humidity of 65% to absorb moisture. Things were used. The other production conditions of the four-layer multilayer printed wiring board are as described above. Then, a solder heat resistance measurement sample cut out to a size of 50 mm × 50 mm from this four-layer multilayer printed wiring board was floated on a 260 ° C. solder bath, and the time until blistering was measured. The results are shown in Table 2. The time until blistering was evaluated as ◯ for 300 seconds or more and x for less than 300 seconds.

[Examples 2 to 7]
In Example 2 to Example 7, instead of the resin composition of Example 1, using the resin components described above, the resin composition of the blending ratio listed in Table 1, and further using dimethylacetamide as a solvent, A resin varnish was prepared. Others are the same as in the first embodiment.

Comparative example

  In Comparative Example 1 and Comparative Example 2, in place of the resin composition of Example 1, using the above-described resin components, a resin composition having a blending ratio listed in Table 1, and further using dimethylacetamide as a solvent, A resin varnish was prepared. Others are the same as in the first embodiment.

  As shown in Table 2, the resin-attached copper foils shown in Examples 1 to 7 had good evaluation results in terms of peel strength, solder heat resistance, flexible performance, and punching performance. In addition, the resin flow was 1% in Examples 1 and 5 and extremely low results in Examples 2 to 4, 4, 6 and 7 less than 1%. In Examples 2 and 3, the punching performance was very good. In addition, the resin flow in the holes formed by punching was small, and good results were obtained. Furthermore, the glass transition temperature Tg could be sufficiently high. In contrast, Comparative Example 1 resulted in inferior punching performance, and Comparative Example 2 resulted in inferior normal solder heat resistance and hygroscopic solder heat resistance.

  The resin composition according to the present invention is compatible with high-density mounting of flexible printed wiring boards, and in particular, has the flexibility and heat resistance of multilayer flexible printed wiring boards, and has high connection reliability and high performance. The present invention can be used for manufacturing a multilayer flexible printed wiring board.

Claims (12)

In the resin composition used to form an adhesive layer for multilayering the inner layer flexible printed wiring board,
A resin composition for forming an adhesive layer of a multilayer flexible printed wiring board comprising the following components A to E:
A component: Solid high heat-resistant epoxy resin having a softening point of 50 ° C. or higher (excluding biphenyl type epoxy resin).
Component B: An epoxy resin curing agent comprising one or more of a biphenyl type phenol resin and a phenol aralkyl type phenol resin.
Component C: A rubber-modified polyamideimide resin soluble in a solvent having a boiling point in the range of 50 ° C to 200 ° C.
D component: An organic phosphorus-containing flame retardant.
E component: Biphenyl type epoxy resin. The resin composition for forming an adhesive layer of a multilayer flexible printed wiring board according to claim 1, further comprising a phosphorus-containing flame retardant epoxy resin as an F component in addition to the components A to E. The G component further includes an epoxy resin composed of one or more selected from the group of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol AD type epoxy resin having an epoxy equivalent of 200 or less and liquid at room temperature. A resin composition for forming an adhesive layer of the multilayer flexible printed wiring board according to claim 1. The resin composition for forming an adhesive layer of a multilayer flexible printed wiring board according to any one of claims 1 to 3, further comprising a low-elasticity substance made of a thermoplastic resin and / or a synthetic rubber as the H component. The solid high heat-resistant epoxy resin in which the softening point of the component A is 50 ° C. or higher is one or more of cresol novolac type epoxy resin, phenol novolac type epoxy resin, and naphthalene type epoxy resin. A resin composition for forming an adhesive layer of a multilayer flexible printed wiring board according to any one of claims 1 to 4. The A component further includes a high heat-resistant epoxy resin composed of one or more of a novolak type epoxy resin, a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, and a naphthalene type epoxy resin that are liquid at room temperature. The resin composition for forming the adhesive layer of the multilayer flexible printed wiring board according to any one of claims 1 to 5. When the weight of the resin composition is 100 parts by weight,
A component is 3 to 30 parts by weight, B component is 13 to 35 parts by weight, C component is 10 to 50 parts by weight, D component is 3 to 16 parts by weight, and E component is 5 parts by weight. It is -35 weight part The resin composition for contact bonding layer formation of the multilayer flexible printed wiring board in any one of Claims 1-6. A resin varnish prepared by adding a solvent to the resin composition according to any one of claims 1 to 7 and having a resin solid content in a range of 30 wt% to 70 wt%,
Resin varnish characterized by having a resin flow in the range of 0% to 10% when measured at a resin thickness of 55 μm in accordance with MIL-P-13949G in the MIL standard when a semi-cured resin layer is formed. . In the copper foil with resin provided with a resin layer on the surface of the copper foil,
The said resin layer was formed using the resin composition for adhesive layer formation of the multilayer flexible printed wiring board in any one of Claims 1-7, For multilayer flexible printed wiring board manufacture characterized by the above-mentioned. Copper foil with resin. The surface with which the resin layer of the said copper foil forms is provided with the silane coupling agent process layer, The copper foil with resin for multilayer flexible printed wiring board manufacture of Claim 9. A method for producing a resin-coated copper foil for producing a multilayer flexible printed wiring board according to claim 9 or 10,
A resin varnish used for forming the resin layer is prepared by the following steps a and b, and the resin varnish is applied to the surface of the copper foil and dried to form a semi-cured resin layer having a thickness of 10 μm to 80 μm. A method for producing a resin-coated copper foil for producing a multilayer flexible printed wiring board, wherein the resin-coated copper foil is used.
Step a: When the weight of the resin composition is 100 parts by weight, the A component is 3 to 30 parts by weight, the B component is 13 to 35 parts by weight, the C component is 10 to 50 parts by weight, and the D component Is a resin composition containing each component in the range of 3 to 16 parts by weight and E component in the range of 5 to 35 parts by weight.
Process b: The said resin composition is melt | dissolved using an organic solvent, and it is set as the resin varnish whose resin solid content amount is 30 weight%-70 weight%. A multilayer flexible printed wiring board obtained by using the resin composition for forming an adhesive layer of the multilayer flexible printed wiring board according to any one of claims 1 to 7.