JP2009132780A - Resin composition for circuit board, insulating layer with supporting substrate, laminate, and circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for circuit boards, an insulating layer with a supporting substrate, a laminate, and a circuit board, which are excellent in high flexibility and heat resistance against repeated thermal history. <P>SOLUTION: The resin composition for circuit boards contains a naphthalene type epoxy resin, a biphenyl aralkyl epoxy resin, a novolac phenolic resin, an amine curing agent, and a phosphoric ester amide. The content of the naphthalene type epoxy resin is 20-50 wt.% of the total resin composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin composition for circuit boards, an insulating layer with a supporting substrate, a laminated board, and a circuit board.

  Flexible printed circuit boards are thin, light, and flexible, so they are used mainly in mobile devices such as mobile phones, camera modules, digital video cameras, digital still cameras, notebook computers, PDAs, and LCD driver modules. However, in recent years, with the improvement in performance and miniaturization of these electronic devices, miniaturization of wiring on a flexible printed circuit board, high-density mounting, flexibility, and the like have been increasingly demanded.

  For example, the flexible printed circuit board used in mobile phones has a high flexion where the clamshell type is a continuous opening and closing of the α-winding hinge part with R = 5 mm or less, and the sliding hinge type part is a continuous sliding with a bending of R = 1 mm or less. Sex is required.

  In addition, as the functionality of small digital devices increases, the flexible printed circuit boards used for them will change from single-sided or double-sided boards to multi-layer boards, or adhere to electromagnetic shielding materials or reinforcing boards, increasing the number of mounting parts. For this reason, heat resistance history is required a plurality of times because mounting is performed a plurality of times or repeated heat history is received.

  In addition, there is a demand for mounting using lead-free solder for environmental reasons, and the mounting temperature is 15-20 ° C higher than that of conventional lead solder. Accordingly, flexible printed circuit boards are required to have high heat resistance and high dimensional stability. It has been.

  Furthermore, it is required that the flame retardant does not contain halogen. Until now, brominated epoxy resins have generally been used as flame retardants (for example, Patent Document 1). However, since there is concern about the generation of dioxins during combustion, halogen-free materials are required.

  As described above, there is a demand for a flexible printed circuit board that has both high flexibility and repeated heat history heat resistance, as well as various characteristics such as high heat resistance and high dimensional stability. The actual situation is that there is no flexible printed circuit board.

As described above, the flexible printed circuit board has been described. However, the invention is not limited to the flexible printed circuit board. For example, a laminated board obtained by laminating an ultrathin prepreg obtained by impregnating an ultrathin glass woven fabric with resin is folded and stored. There has been the same problem that a circuit board using a laminated board having various properties such as properties, heat resistance, heat history resistance, and dimensional stability is required.
JP 2001-098243 A

  The present invention has been made in view of the above circumstances, and has a resin composition for circuit boards, with a supporting base material, which has excellent balance between high flexibility and repeated heat history heat resistance while maintaining other characteristics. An object is to provide an insulating layer, a laminate, and a circuit board.

  A resin composition for a circuit board according to the present invention is a resin composition used for a circuit board, which is a naphthalene type epoxy resin, a biphenyl aralkyl type epoxy resin, a novolac type phenol resin, an amine curing agent, and a phosphate ester. And an amide.

  Thereby, it can be set as the resin composition for circuit boards excellent in high flexibility and repeated heat history heat resistance.

  Further, it may further contain a carboxylic acid-modified nitrile butadiene rubber. Thereby, it can be set as the resin composition for circuit boards excellent in the adhesiveness with respect to both polyimide and copper foil materials.

  Furthermore, the insulating layer with a supporting base material in which the insulating layer which consists of the resin composition for circuit boards was formed in the at least one surface side of the supporting base material which consists of metal foil or a resin film can be provided.

  Moreover, it is good also as a laminated board by which metal foil was laminated | stacked by the insulating layer which consists of a resin composition for circuit boards on the at least one surface side of the support base material which consists of the said resin film, and also the said laminated board A metal foil is etched to form a conductor circuit, and is laminated so as to cover the conductor circuit through an insulating layer made of a resin composition for circuit boards formed on one surface side of the support substrate made of the resin film. It is good also as a formed circuit board.

  It is possible to provide a resin composition for circuit boards, an insulating layer with a supporting substrate, a laminated board, and a circuit board excellent in the balance between high flexibility and repeated heat history heat resistance while maintaining other characteristics.

  Hereinafter, the resin composition for circuit boards, the insulating layer with a supporting substrate, the laminate and the circuit board of the present invention will be described in detail.

  The resin composition for circuit boards of the present invention can be used as a coverlay film in which an insulating layer is formed on one side of a resin film such as a polyimide film as a supporting substrate, or a resin composition for circuit boards on one or both sides of the resin film. It can be used as a laminated board for flexible printed circuit boards by forming an insulating layer and laminating and bonding to a metal foil.

  Hereinafter, each component which comprises the resin composition for circuit boards of this invention is demonstrated.

  The resin composition for circuit boards of the present invention comprises a naphthalene type epoxy resin, a biphenyl aralkyl type epoxy resin, a novolac type phenol resin, an amine curing agent, and a phosphoric ester amide. .

  The resin composition for circuit boards of this invention contains a naphthalene type epoxy resin and a biphenyl aralkyl type epoxy resin. These epoxy resins contain many benzene rings in the molecule. The rigid skeleton by this can obtain the effect of low water absorption and the effects of flame retardancy and heat resistance on the molecular structure.

  As the naphthalene type epoxy resin, an epoxy resin represented by the following chemical formula (1) can be used.

  Moreover, as a biphenyl aralkyl type epoxy resin, the epoxy resin represented by following Chemical formula (2) can be used.

  The content of the naphthalene type epoxy resin is preferably 20% by weight or more and 50% by weight or less, more preferably 25% by weight or more and 40% by weight or less, based on the entire resin composition. If the content of naphthalene-type epoxy resin is within this range, the resin composition varnish for circuit boards is applied to the film and dried to impair handling properties such as no powder falling off when a coverlay film is obtained. High flexibility and heat resistance can be obtained.

  Further, the content of the biphenyl aralkyl type epoxy resin is preferably 5% by weight or more and 45% by weight or less, more preferably 10% by weight or more and 35% by weight or less of the entire resin composition. If the content of the biphenyl aralkyl type epoxy resin is within this range, high flexibility, heat resistance, and repeated heat history can be obtained.

  The blending ratio of the naphthalene type epoxy resin and the biphenyl aralkyl type epoxy resin is preferably 40% by weight or more and 90% by weight or less, more preferably 90% by weight or less when the total of both epoxy resins is 100% by weight. Is 50% by weight or more and 80% by weight or less. If the blending ratio is within this range, the resin composition varnish for circuit boards is applied to the film and dried to obtain a coverlay film. Excellent heat resistance and repeated heat history.

  In addition to the bifunctional epoxy resin, one or more of biphenyl type, anthracene type, xanthene type, dicyclopentadiene type, or bisphenol S type may be included. Thereby, the rigid skeleton can obtain the effect of reducing water absorption and the effect of flame retardancy and heat resistance on the molecular structure.

  The resin composition for circuit boards of the present invention contains a novolac type phenol resin. Although it does not specifically limit as a novolak phenol resin, It is preferable that it is an aminotriazine novolak type phenol resin. Due to the presence of amino groups, some of the epoxy groups react with the heat during coating, resulting in a B-stage. Thereby, seepage at the time of lamination press is suppressed.

  Furthermore, nitrogen in the triazine part contributes to flame retardancy. Although content of novolak phenol resin is not specifically limited, It is preferable to contain 0.6 to 1.2 equivalent with respect to the total epoxy group contained in this invention. More preferably, it is 0.7 to 1.1 equivalent. When the equivalent is 0.6 or less, curing is insufficient, and when it is 1.2 or more, warpage associated with curing shrinkage tends to occur. As the aminotriazine novolac type phenol resin, for example, a novolac type phenol resin represented by the following chemical formula (3) can be used.

  The content of the novolak type phenol resin is preferably 20% by weight or more and 40% by weight or less, more preferably 25% by weight or more and 35% by weight or less based on the entire resin composition.

  If the content of the novolak-type phenol resin is within this range, it is possible to suppress the seepage during lamination pressing.

  The resin composition for circuit boards of the present invention contains an amine curing agent. Examples of the amine curing agent include diaminodiphenylmethane, diaminodiethyldiphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, isophoronediamine, norbornenediamine, and the like. The presence of the amino group promotes the reaction of the novolac type phenolic resin and a part of the epoxy groups by the heat at the time of coating, thereby forming a B stage. Thereby, seepage at the time of lamination press is suppressed. Furthermore, it is possible to obtain excellent adhesion to a substrate film such as polyimide, and it is also excellent in repeated heat history.

  Although content of an amine hardening | curing agent is not specifically limited, 0.1 to 5 weight% of the whole resin composition is preferable, and 0.5 to 3 weight% is more preferable. When the content is within this range, high flexibility, heat resistance, and heat history can be obtained. As the amine curing agent, an amine curing agent represented by the following chemical formula (4) can be used.

  The resin composition for circuit boards of this invention contains phosphoric ester amide. Phosphoric ester amide is effective as a flame retardant containing no halogen. Compared to phosphoric acid esters, which are general phosphorus compounds, the hydrolytic property is small, so that the heat resistance of moisture-absorbing solder is improved and the migration resistance (insulation reliability) is not lowered.

  The content of phosphoric ester amide is preferably 5% by weight or more and 30% by weight or less based on the entire resin composition for circuit boards. More preferably, it is 7 to 25 weight%. If the content is within this range, flame retardancy can be imparted without impairing physical properties. A phosphorous ester amide having a phosphorus content of 5 mol% or more and 15 mol% or less can be used. As phosphate ester amide, what is represented, for example by following Chemical formula (5) is used.

  The circuit board resin composition of the present invention may further contain a carboxylic acid-modified nitrile butadiene rubber. Carboxylic acid-modified nitrile butadiene rubber is effective in improving adhesion to both materials of resin film and metal foil.

  The content of the carboxylic acid-modified nitrile butadiene rubber is preferably 3% by weight or more and 20% by weight or less based on the total resin composition for circuit boards. More preferably, it is 5 to 15 weight%. When the content is at least the lower limit, the adhesion and handling properties are improved. When the content is not more than the upper limit, the heat resistance, in particular, the heat history characteristics such as multiple presses is excellent.

  The resin composition for circuit boards of the present invention may contain components other than those described above. For example, additives such as silane coupling agents such as epoxy silane or titanate coupling agents, antifoaming agents, surface conditioning agents, and imidazole compounds to improve adhesion to metal foils and circuit boards and moisture resistance And a curing accelerator such as triphenylphosphine may be included.

  Next, the insulating layer with a supporting substrate of the present invention will be described.

  The insulating layer with a supporting substrate is obtained by forming an insulating layer made of a resin composition for circuit boards on at least one surface side of a supporting substrate made of a metal foil or a resin film.

  An insulating layer with a supporting substrate using a resin film as a supporting substrate is used to cover and protect the surface of a conductor circuit provided on a circuit board, and in particular, as a coverlay film in a flexible circuit board. Yes. Moreover, you may use the insulating layer with a support base material which used metal foil as a support base material as RCC (Resin Coated Copper). This can also be used as a build-up material for multilayer circuit boards.

  The cover lay film, which is coated as a varnish on one side of a resin film and dried to provide an insulating layer, is coated with a varnish dissolved in a prescribed concentration in the above resin composition for circuit boards. After that, drying is performed at 80 ° C. or higher and 200 ° C. or lower. About the thickness of the resin composition for circuit boards after drying, it coats so that it may become the range of 10 micrometers or more and 100 micrometers or less by a use. In the case of a coverlay film, a film such as polyethylene terephthalate, polyethylene, or polypropylene may be used as a release film on the surface of the resin composition after drying for the purpose of preventing foreign matter from entering.

  As the solvent used for the varnish, it is preferable to select a solvent having good solubility in the resin composition. For example, one or two of acetone, methyl ethyl ketone, toluene, xylene, n-hexane, methanol, ethanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methoxypropanol, cyclohexanone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc. It is possible to use the above mixed system.

  Examples of the resin film include polyimide resin films such as polyimide resin films, polyetherimide resin films and polyamideimide resin films, polyamide resin films such as polyamide resin films, and polyester resin films such as polyester resin films. Among these, a polyimide resin film is particularly preferably used from the viewpoint of improving the elastic modulus and heat resistance.

  Although the thickness of a resin film is not specifically limited, 5 micrometers or more and 50 micrometers or less are preferable, More preferably, they are 5 micrometers or more and 25 micrometers or less. When the thickness is within this range, the flexibility is particularly excellent.

  Insulating layer (RCF) with a supporting substrate using metal foil is applied to metal foil with a resin composition for circuit boards dissolved in a predetermined solvent and a predetermined concentration in the same manner as the coverlay film described above. After that, drying is performed at 80 ° C. or higher and 200 ° C. or lower. About the thickness of the resin composition for circuit boards after drying, it coats so that it may become the range of 8 micrometers or more and 50 micrometers or less by a use. Also in the case of RCF, a film such as polyethylene terephthalate, polyethylene, or polypropylene may be used as a release film on the circuit board resin composition after drying for the purpose of preventing foreign matter from entering.

  Examples of the metal constituting the metal foil include copper and a copper-based alloy, aluminum and an aluminum-based alloy, iron and an iron-based alloy, and copper is more preferable.

  Although the thickness of metal foil is not specifically limited, 6 micrometers or more and 70 micrometers or less are preferable, and 9 micrometers or more and 18 micrometers or less are especially preferable. When the thickness is within this range, the flexibility and folding resistance are particularly excellent. What is necessary is just to select suitably the solvent similar to the solvent used for the coverlay film mentioned above as a solvent used for a varnish.

  Next, the laminated board of this invention is demonstrated.

  In the laminated plate, a metal foil is laminated and formed on at least one surface side of the supporting substrate made of the resin film via an insulating layer made of a resin composition for circuit boards.

  The laminate is prepared by applying a varnish on one or both sides of a base material and drying it, and then laminating a metal foil on the resin composition surface by a thermocompression roll or the like.

  Examples of the metal constituting the metal foil include copper and a copper-based alloy, aluminum and an aluminum-based alloy, iron and an iron-based alloy, and copper is more preferable.

  Examples of the base material include an insulating film. Examples of the resin film include a polyimide resin film such as a polyimide resin film, a polyetherimide resin film, and a polyamideimide resin film, and a polyamide resin such as a polyamide resin film. Examples thereof include polyester resin films such as films and polyester resin films. Among these, a polyimide resin film is particularly preferably used from the viewpoint of improving the elastic modulus and heat resistance. Further, as a base material, a metal foil may be laminated and bonded to a prepreg obtained by impregnating a base material such as a glass woven fabric, a glass nonwoven fabric, or a polyester nonwoven fabric with a resin composition for circuit boards.

  What is necessary is just to select suitably the solvent similar to the solvent used for the coverlay film mentioned above as a solvent used for a varnish.

  Next, the circuit board of the present invention will be described.

  In the circuit board of the present invention, a conductive circuit is formed by etching a metal foil of a laminated board, and an insulating layer (cover lay film) made of a resin composition for circuit boards is formed on one surface side of a support base made of a resin film. And are formed so as to cover the conductor circuit. In the above coverlay film, unnecessary portions are removed in advance. As a removing method, for example, it may be punched out using a mold or the like, or drilled with an NC drill, NC router or the like. From the viewpoint of workability and productivity, it is preferable to punch using a mold. And a method of laminating a coverlay film on a necessary part of a conductor circuit, and carrying out pressure bonding with a hot-pressure forming device can be used. In this case, the pressure bonding conditions can be, for example, a pressure bonding temperature of 80 ° C. or higher and 220 ° C. or lower and a pressure bonding pressure of 0.2 MPa or higher and 10 MPa or lower.

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

Example 1
34 parts by weight of naphthalene type epoxy resin (Dainippon Ink & Chemicals, Inc .: EPICLON HP-4032D, epoxy equivalent 140) as an epoxy resin, biphenyl aralkyl type epoxy resin (Nippon Kayaku Co., Ltd .: NC-3000H) , Epoxy equivalent 290) 14 parts by weight, 29 parts by weight of an aminotriazine novolak type phenol resin (Dainippon Ink & Chemicals, Inc .: Phenolite LA7054, hydroxyl group equivalent 125) represented by Chemical Formula 3 as a curing agent, amine series 1 part by weight of a curing agent (Nippon Kayaku Co., Ltd .: KAYAHARD A-A), 10 parts by weight of a flame retardant containing phosphoric ester amide (Shikoku Kasei: SP-703) represented by Chemical Formula 5, 9 parts by weight of acid-modified NBR (manufactured by Nippon Zeon Co., Ltd .: Levital 1072J), coupling agent ( Nmentibu Performance Materials Japan LLC made: 3 parts by weight of SILQUEST A-187 SILANE), these resin solids in a mixed solvent of MEK and cyclohexanone were dissolved to be 50%.

  This compound varnish was coated on a single side of a polyimide film having a thickness of 12.5 μm with a comma roll coater so that the thickness of the resin composition for circuit boards was 10 μm, and dried at 120 ° C. for 5 minutes + 150 ° C. for 5 minutes. Then, a rolled copper foil (18 μm thick, manufactured by Fukuda Metal Foil Industry Co., Ltd.) was laminated by a hot roll at 150 ° C., and then the varnish was coated on the opposite side, dried, and the rolled copper foil was laminated. This was cured at 180 ° C. for 1 hour to obtain a copper clad laminate for a flexible printed circuit board.

  A predetermined circuit was produced from this by a normal circuit production process (drilling, plating, DFR lamination, exposure / development, etching, DFR peeling) to obtain a substrate for evaluation.

  Furthermore, the same composition varnish was coated on one side of a polyimide film having a thickness of 12.5 μm with a comma roll coater so that the thickness of the resin composition for circuit boards was 20 μm, and 120 ° C. for 5 minutes + 150 ° C. for 5 minutes. It dried and the coverlay film was obtained. An opening was provided at a predetermined position of the cover lay film, and a flexible printed circuit board for evaluation was manufactured by attaching it to a predetermined position on both sides of the previously prepared evaluation substrate with a vacuum press at 160 ° C. for 1 hour.

  Next, a flexible printed circuit board for evaluation was produced in the same manner as in Example 1 with the formulation shown in Table 1.

  The flexible printed circuit board thus obtained was measured for formability, adhesion, heat history heat resistance, electrical insulation, bendability, folding resistance, flame resistance, and handling properties, and the results are shown in Table 1. Shown in

* Formability: The maximum amount of protrusion from the edge of the coverlay film punched out to expose the measurement terminals was 0.2 mm or less, and there were no voids due to embedment defects such as between circuits. Was marked as ○.
* Adhesive strength Conforms to JIS standard C5016-8.1. Adhesive strength is 1.0 N / mm or more ◎, 0.6 N / mm or more and less than 1.0 N / mm ○, 0.4 N / mm or more and less than 0.6 N / mm △, less than 0.4 N / mm × It was.
* Repeated heat history heat resistance The obtained flexible printed circuit board was repeatedly subjected to vacuum press three times under the conditions of 180 ° C., 2 MPa, and 1 hour, and the peel strength of the test piece was measured. When the peel strength was 0.5 N / mm or more, it was evaluated as ◯, 0.3 N / mm or less as Δ, and less than 0.1 N / mm as x.
* Electrical insulation Using a comb-shaped pattern with a circuit width and an inter-circuit width of 50 μm, the initial state and the insulation resistance value after treatment at 85 ° C. and 85% for 50 V for 1000 hours were measured. A sample having an insulation resistance value of 10 ⁸ or more both after the initial value and after the treatment was evaluated as ◯.
* Flexibility Conforms to the IPC method. R = 2 mm, 1000 rpm, stroke 15 mm, the number of flexing times is 10 million times or more, ◎, 5 million times to less than 10 million times ○, 100,000 times to less than 5 million times △, 10 What was less than 10,000 times was set as x.
* Folding resistance A double-sided board with a circuit width of 1 cm and a circuit width of 100 μm is folded by 180 ° in the direction perpendicular to the circuit and opened, and the same part is folded and opened again. By repeating this, the change rate of the conduction resistance value was less than 1% compared to the initial value, ◎, 1% to less than 5%, ％, 5% to less than 10%, ％, and 10% or more to ×.
* Flame retardance Evaluated based on UL method. V-0 or VTM-0 was marked with ◎, V-1 or VTM-1 was marked with ◯, and the others were marked with x.
* Handling (as coverlay)
A coverlay obtained by attaching a coverlay obtained on a copper-clad plate heated to 50 ° C. without causing powder falling off was marked with “◯”.

  From the above results, the flexible printed circuit boards obtained from the resin compositions for circuit boards of Examples 1 to 18 are all in moldability, adhesion, repeated heat history heat resistance, flexibility, folding resistance and the like. Good results were obtained.

Claims (12)

Naphthalene type epoxy resin,
Biphenyl aralkyl epoxy resin,
Novolac type phenolic resin,
An amine-based curing agent;
Phosphoric ester amide,
A resin composition for circuit boards, comprising:   The blending ratio of the naphthalene type epoxy resin and the biphenyl aralkyl type epoxy resin is 40% by weight or more and 90% by weight or less of the naphthalene type epoxy resin when the total of both epoxy resins is 100% by weight. Item 2. The resin composition for circuit boards according to Item 1.   The resin composition for circuit boards according to claim 1 or 2, wherein the cured product of the resin composition for circuit boards has a storage elastic modulus at 25 ° C of 1 GPa or more.   4. The circuit board resin composition according to claim 1, wherein a content of the naphthalene type epoxy resin is 20% by weight or more and 50% by weight or less of the entire resin composition. 5.   5. The resin composition for a circuit board according to claim 1, wherein the content of the biphenyl aralkyl type epoxy resin is 5% by weight or more and 45% by weight or less of the entire resin composition.   6. The circuit board resin composition according to claim 1, wherein the novolac type phenol resin is an aminotriazine novolac type phenol resin or an aminotriazine cresol novolac type phenol resin.   The circuit board resin composition according to any one of claims 1 to 6, wherein a content of the phosphoric ester amide is 5% by weight or more and 30% by weight or less of the entire resin composition.   The resin composition for circuit boards according to any one of claims 1 to 7, further comprising a carboxylic acid-modified nitrile butadiene rubber.   The resin composition for a circuit board according to claim 8, wherein the content of the carboxylic acid-modified nitrile butadiene rubber is 3% by weight or more and 20% by weight or less of the entire resin composition.   The insulating layer with a supporting base material in which the insulating layer which consists of the resin composition for circuit boards in any one of Claim 1 thru | or 9 was formed in the at least one surface side of the supporting base material which consists of metal foil or a resin film.   The laminated board by which metal foil was laminated | stacked and formed on the at least one surface side of the support base material which consists of a resin film of Claim 10 via the insulating layer which consists of a resin composition for circuit boards.   A conductive circuit is formed by etching the metal foil of the laminated board according to claim 11, and an insulating layer made of a resin composition for a circuit board formed on one surface side of a support base made of a resin film is provided. A circuit board laminated to cover the conductor circuit.