JP2002353583A - Resin-attached metal foil and multilayered printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-fitted metal foil, capable of providing a multilayer printed wiring board where less warpage/deflection occurs at reflowing for component mounting, and to provide a multilayered printed wiring board where less warpage/deflection occurs at reflowing for component mounting. SOLUTION: A resin-attached metal foil is provided, which is formed by providing a resin layer on one surface of a metal foil, which has thermal fusion property and thermosetting property. The resin layer comprises a woven material or a nonwoven material. The resin layer side of the resin-attached metal foil is manufactured in a process of stacking it on an inner-layer substrate which forms a conductor circuit for lamination/molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal foil with resin used for manufacturing a multilayer printed wiring board and the like, and a multilayer printed wiring board manufactured using the metal foil with resin.

[0002]

2. Description of the Related Art In recent years, a material called a metal foil with resin has been widely used for manufacturing a multilayer printed wiring board and the like. The resin-coated metal foil is applied in a semi-cured state (B stage) by applying a resin varnish such as an epoxy resin varnish (epoxy resin composition) to one surface of a metal foil such as a copper foil and drying the same. Generally, it is manufactured by forming a resin layer which is heat-meltable and has thermosetting properties. Here, being capable of being thermally melted and having thermosetting means that it can be melted once by heating and then gelled to form a cured product.

A multilayer printed wiring board manufactured using a resin-attached metal foil satisfies recent demands for lightness, thinness and shortness. In the case of a multilayer printed wiring board manufactured using a resin-attached metal foil, The elastic modulus of the multilayer printed wiring board tends to be low, and warpage and deflection occur during reflow of component mounting, causing a problem that component mounting becomes difficult. In particular, this tendency becomes remarkable in the case of a multilayer printed wiring board obtained by arranging metal foils with resin on the front and back of the inner layer substrate and laminating them.

[0004] Further, there is an increasing demand for miniaturization of circuits of a multilayer printed wiring board. To meet the demand, a metal foil with a resin having a thickness of less than 12 μm (for example, 9 μm, 5 μm, etc.) and an inner layer It has been studied to form a circuit on a laminate formed by stacking substrates for use. Thickness 12
In the case of ultra-thin metal foil of less than μm (for example, ultra-thin copper foil),
Since the thickness is very thin and wrinkles or the like are formed during handling, a metal foil (such as a copper foil or an aluminum foil) having a thickness of about 35 μm is generally provided with a carrier foil. However, the ultrathin metal foil with a carrier foil requires a step of peeling the carrier foil after lamination and has a problem of recovery of the carrier foil, and the use thereof has not been widespread at present. Similarly, the use of ultra-thin metal foil with resin using ultra-thin metal foil with a carrier foil is currently not widely used, and a new ultra-thin metal foil with resin, which is unlikely to cause wrinkles during handling, has been developed. It has been demanded.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an advantage that a multilayer printed wiring board manufactured using a resin-coated metal foil can have a high elastic modulus.
An object of the present invention is to provide a resin-attached metal foil capable of obtaining a multilayer printed wiring board capable of reducing the occurrence of warpage and deflection during reflow of component mounting. It is another object of the present invention to provide a multilayer printed wiring board having a high elastic modulus manufactured by using the resin-attached metal foil and reducing occurrence of warpage and warpage during reflow of component mounting. It is another object of the present invention to provide a new type of ultrathin metal foil with resin that is less likely to cause wrinkles or the like during handling, instead of using an ultrathin metal foil with resin using an ultrathin metal foil with a carrier foil. Here, the ultrathin metal foil refers to a metal foil having a thickness of 9 μm or less.

[0006]

The resin-coated metal foil according to the first aspect of the present invention is a resin-coated metal foil formed by providing a heat-fusible and thermosetting resin layer on one side of the metal foil. Further, the resin-coated metal foil is characterized in that the resin layer includes a woven fabric or a nonwoven fabric.

[0007] The term "heat-fusible and thermosetting" as used herein means that the material can be melted once by heating and then gelled to form a cured product.

[0008] The metal foil with resin of the invention according to claim 2 is
2. The resin-attached metal foil according to claim 1, wherein the thickness of the metal foil is 9 μm or less.

The metal foil with resin of the invention according to claim 3 is:
The resin-attached metal foil according to claim 1 or 2, wherein the woven fabric provided in the resin layer is a glass cloth.

[0010] The metal foil with resin of the invention according to claim 4 is as follows.
The metal foil with resin according to claim 1 or 2, wherein the nonwoven fabric provided in the resin layer is a nonwoven fabric of organic fibers.

[0011] The metal foil with resin of the invention according to claim 5 is as follows.
The resin-attached metal foil according to any one of claims 1 to 4, wherein the cured product of the resin layer has a dielectric constant of 5 or less.

[0012] The metal foil with resin of the invention according to claim 6 is:
The resin-coated metal foil according to any one of claims 1 to 5, wherein the thickness of the resin layer is 30 to 200 µm.

[0013] The metal foil with resin of the invention according to claim 7 is:
A resin layer side of the metal foil with resin according to any one of claims 1 to 6, which is manufactured through a step of laminating and molding by laminating an inner layer substrate forming a conductor circuit. This is a multilayer printed wiring board.

[0014]

Embodiments of the present invention will be described below.

As the metal foil used for producing the metal foil with resin according to the present invention, for example, an electrolytic copper foil, an aluminum foil or the like can be used.

The resin-attached metal foil according to the present invention is provided with a heat-fusible and thermosetting resin layer on one surface thereof, and the resin layer is provided with a woven or nonwoven fabric. Examples of the woven fabric include a glass cloth and a woven fabric of various organic fibers. However, it is preferable to use a glass cloth because it is easily available and the elastic modulus of the multilayer printed wiring board can be increased. On the other hand, as the nonwoven fabric, nonwoven fabrics using various fibers can be used, but it is easy to use nonwoven fabrics of organic fibers such as aramid fibers, polyester fibers, polyimide fibers, and polyacrylic fibers. This is preferable because the elastic modulus of the printed wiring board can be increased. Further, when the dielectric constant of the cured resin layer is high, the performance of the multilayer printed wiring board tends to decrease. Therefore, it is necessary to control the dielectric constant of the cured resin layer to be 5 or less. It is preferable to ensure the performance of the printed wiring board. Since the dielectric constant of the glass fiber greatly varies depending on the constituent material, it is preferable to use a glass fiber using a constituent material having a low dielectric constant as long as performance such as workability can be ensured. As a preferable glass fiber, a glass fiber using E glass or D glass as a constituent material can be exemplified.

The heat-meltable and thermosetting resin layer is formed by using a varnished thermosetting resin composition such as an epoxy resin composition or a polyimide resin composition. I do. When an epoxy resin composition is used, for example, a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, a bisphenol A type epoxy resin, or a bromide thereof can be used as an epoxy resin as a main component. As a curing agent for the epoxy resin, for example, dicyandiamide or phenol novolak resin can be used. Further, if necessary, a curing accelerator, various additives, a solvent,
An inorganic filler or the like can be contained in the epoxy resin composition. As the curing accelerator, for example, 2-ethyl-4
Imidazoles such as -methylimidazole, dimethylbenzylamine and the like can be used. In addition, liquefaction of the epoxy resin composition can be easily achieved by blending a solvent. As the solvent, for example, methyl ethyl ketone (MEK), methoxypropanol (MP), dimethylformamide (DMF), or the like is used. it can. Then, the epoxy resin composition (epoxy resin varnish) which is liquefied by mixing these components such as the epoxy resin and the curing agent and mixing with a mixer or a blender can be produced.

The metal foil with resin according to the present invention is obtained by impregnating a woven or nonwoven fabric with the liquefied thermosetting resin composition.
Metal foil on one surface of the dried prepreg,
A cover film such as a PET film can be provided on the other surface, and these can be continuously integrated by using, for example, a vacuum laminator or the like. In this way,
Formed on one side of the resin-attached metal foil, is a heat-meltable and thermosetting resin layer, the thickness of the resin layer having a woven or nonwoven fabric is not particularly limited, Preferably it is 30 to 200 μm. When a multilayer printed wiring board is manufactured using a metal foil with a resin in which the thickness of the resin layer is less than 30 μm, the unevenness of the inner layer substrate having the conductive circuit is filled with the resin component of the metal foil with a resin. When a multilayer printed wiring board is manufactured using a resin-coated metal foil having a resin layer thickness exceeding 200 μm, the insulating layer tends to be too thick. It is.

The thickness of the metal foil in the resin-coated metal foil according to the present invention is not particularly limited, but may be 9 μm.
The following is preferable because a fine circuit can be easily formed. Note that the lower limit of the thickness is not particularly limited as long as the circuit can be formed. Then, the thickness of the metal foil itself is 9 μm with the metal foil with resin according to the present invention.
In the case of the following, since the resin layer is provided with a woven fabric or a nonwoven fabric, the metal foil with resin is less likely to cause wrinkles and the like during handling, and has improved workability. That is, the resin-attached metal foil of the present invention can provide an ultrathin resin-attached metal foil which can prevent wrinkles and the like from occurring during handling without integrating the carrier foil.

A multilayer printed wiring board according to a seventh aspect of the present invention is manufactured using the above-described resin-coated metal foil of the present invention. That is, the resin layer side of the above-described resin-attached metal foil,
It is manufactured through a process of superimposing on one or both surfaces of an inner layer substrate forming a conductor circuit, and heating and pressing the superimposed product to form a laminate.

The laminated metal foil and the substrate for the inner layer are integrated by performing the above-mentioned lamination molding, and a hole is formed by drilling with a laser or the like, plating with copper or the like to form a via hole, and then forming a via hole. A multilayer printed wiring board is manufactured by further processing such as forming a circuit pattern to be an outer layer circuit on the metal foil by a method such as a subtractive method.

The multilayer printed wiring board thus obtained uses a resin-coated metal foil having a woven or non-woven fabric in the resin layer, so that a multilayer printed wiring board having a high elastic modulus can be obtained. . Therefore, warpage and deflection generated in the multilayer printed wiring board at the time of reflow for component mounting on the multilayer printed wiring board are reduced. Further, when the thickness of the metal foil of the resin-attached metal foil is 9 μm or less,
A multilayer printed wiring board on which a fine circuit can be formed accurately and easily.

[0023]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples. Examples 1 to 6 and Comparative Examples 1 to 3 <Preparation of Epoxy Resin Composition (Varnish)> As an epoxy resin, a brominated bisphenol A type epoxy resin (“YDB-500” manufactured by Toto Kasei Co., Ltd .: epoxy equivalent) 500, a bromine content of about 24% by mass) and a cresol novolak type epoxy resin (“YDCN-220” manufactured by Toto Kasei: epoxy equivalent 220). As a curing agent, dicyandiamide (molecular weight 84, theoretically active hydrogen equivalent 21) was used.
2-ethyl-4-methylimidazole is used as a curing accelerator, methyl ethyl ketone (MEK) as a solvent,
Methoxypropanol (MP) and dimethylformamide (DMF) were used.

The proportions of the above components in Examples 1 to 6 and Comparative Examples 1 to 3 are as follows. 60 parts by mass of brominated bisphenol A type epoxy resin, 10 parts by mass of cresol novolak type epoxy resin, 2 parts by mass of dicyandiamide, 0.1 parts by mass of 2-ethyl-4-methylimidazole, 15 parts by mass of methyl ethyl ketone, methoxy 5 parts by mass of propanol and 15 parts by mass of dimethylformamide were blended. In Comparative Example 3, spherical silica was also added, and the compounding ratio was such that spherical silica was 40% by volume based on the total amount of the components excluding the solvent and the spherical silica.

Using a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.
Rotating speed of epoxy resin, hardener and solvent 1000rpm
The mixture was mixed by stirring at 90 m for 90 minutes (spherical silica was also added in Comparative Example 3), then a curing accelerator (2-ethyl-4-methylimidazole) was added, and the rotation speed was again set to 1000 rpm.
m, and then degassed to prepare a varnish of the epoxy resin composition.

<Preparation of Prepreg> Examples 1 to 6
Then, the base material (nonwoven fabric of glass cloth or aramid fiber) provided in the resin layer shown in Tables 1 and 2 is impregnated with the varnish of the epoxy resin composition prepared as described above, and the impregnated one is a non-contact type. By heating and drying at 160 ° C. by a heating unit, the solvent in the varnish is dried and removed, and the epoxy resin composition is semi-cured, and the curing time (gelling time) is 1
Prepregs at 150C for 70 seconds were made for each example.

<Production of Copper Foil with Resin> In Examples 1 to 6, one prepreg, a copper foil having a thickness shown in Tables 1 and 2, and a PET film having a thickness of 35 μm were prepared. The prepreg is arranged at the center position, guided into a vacuum pressurized laminator (product number MVLP-500) manufactured by Meiki Seisakusho, continuously bonded, and sandwiched with a resin layer with a copper foil and a cover film (PE).
A T-film) was formed into a resin-coated copper foil. Laminator conditions are: hot platen temperature 100 ° C, suction time 6
The test was performed at 0 seconds, a pressurizing time of 60 seconds and a pressure of 0.1 MPa. In Comparative Examples 1 to 3, a varnish of the epoxy resin composition prepared as described above was applied to the copper foil shown in Table 3 and dried by heating to prepare a resin-coated copper foil. The thickness of the resin layer of each of the obtained copper foils with resin was as shown in Tables 1 to 3. In Comparative Example 3, although a carrier copper foil having a thickness of 35 μm, which is a carrier foil, and an ultra-thin copper foil having a thickness of 5 μm were integrated, a varnish of an epoxy resin composition was applied to the ultra-thin copper foil surface. I made it.

<Production of multilayer printed wiring board>
In Example 6, Comparative Examples 1 to 3, the substrate thickness was 0.2 m.
m FR-4 grade double-sided copper-clad laminate (copper foil thickness 35
μm) copper foil subjected to a surface treatment (blackening treatment) was used as an inner layer substrate. The resin layer surface exposed by peeling off the resin-coated copper foil cover film prepared as described above is overlapped on both surfaces of the inner layer substrate, and pressurized at 2.94 MPa while heating at 170 ° C. for 90 minutes. The substrate and two pieces of copper foil with resin were integrated (however, in Comparative Examples 1 to 3, copper foil with resin without a cover film was used). Thereafter, each step of forming a pattern resist, etching and removing the resist was performed on the copper foil on the surface, thereby producing a multilayer printed wiring board for evaluation having an outer layer circuit pattern formed for each example. In Comparative Example 3, the outer layer circuit pattern was formed on a copper foil having a thickness of 5 μm, which was exposed by peeling off the carrier copper foil on the surface.

<Evaluation> For each of the obtained copper foils with resin and the multilayer printed wiring boards for evaluation in Examples 1 to 6 and Comparative Examples 1 to 3 obtained above, the pattern accuracy of the outer layer circuit was determined.
Each evaluation item of the dielectric constant of the cured resin layer, the elastic modulus of the cured resin layer, and the laser workability was evaluated by the following measurement methods, and the obtained results are shown in Tables 1 to 3. As described in the following measurement method, the amount of warpage due to the reflow step was evaluated by separately producing a multilayer printed wiring board for evaluating warpage, and the obtained results are shown in Tables 1 to 3.

Evaluation method of pattern accuracy of outer layer circuit: The outer layer circuit pattern formed on the multilayer printed wiring board for evaluation is
Line width / inter-line spacing is 20 μm / 20 μm, 30 μm
m / 30 μm, 40 μm / 40 μm, 50 μm / 50 μ
m, 100 μm / 100 μm, 5 types (5 levels)
A multi-layer printed wiring board for evaluation was prepared so as to be provided with the test pattern described above, and up to which level of the fine circuit pattern could be formed without a defect such as disconnection or short-circuit was observed with a microscope, and the pattern could be formed without a defect. Evaluate the limits.

Evaluation method of the dielectric constant of the cured resin layer: The dielectric constant of the cured resin layer of the copper foil with the resin is expressed as I
Measure according to PC standard TM-650 2.5.5.9 (measurement frequency 1 MHz). The test piece was used in Examples 1 to 6.
The thickness after molding the prepreg as the resin layer is about 1.0mm
Laminate molding with copper foils on both sides of the laminated material (molding conditions: temperature 170 ° C., pressure 2.94MP)
a, heating and pressurizing time: 90 minutes), and the front and back copper foils of the obtained double-sided copper-clad laminate are etched on the front side. Comparative Example 1
In Comparative Example 3, resin powder obtained by stripping a resin portion from a resin-coated copper foil is collected, poured into a mold having a measured shape, and press-molded (molding conditions: temperature 170 ° C., pressure 2.94MP).
a, heating and pressurizing time: 90 minutes) to produce a test piece having a thickness of about 1.0 mm.

Evaluation method of the elastic modulus of the cured resin layer: The elastic modulus of only the resin layer of the resin-coated copper foil was measured according to JIS standard C64.
Measure according to No.81. In Examples 1 to 6, a test piece was prepared by laminating prepregs as resin layers so that the thickness after molding was about 1.6 mm and arranging copper foils on both sides of the prepreg (forming conditions). : A temperature of 170 ° C., a pressure of 2.94 MPa, and a heating and pressing time of 90 minutes), and the front and back copper foils of the obtained double-sided copper-clad laminate are etched on the front surface. In Comparative Examples 1 to 3, resin powder obtained by stripping the resin portion from the resin-coated copper foil was collected, poured into a mold having a measured shape, and press-molded (molding conditions: temperature 170 ° C., pressure 2.94 MPa, Heating and pressurizing time of 90 minutes)
A test piece having a thickness of mm is prepared.

Evaluation method of laser workability: A hole for forming a via hole was formed in the obtained multilayer printed wiring board by a carbon dioxide laser (“ML605G” manufactured by Mitsubishi Electric Corporation).
TX-5100U ”), and it is examined how many shots can be formed in the resin layer of the resin-coated copper foil when a hole having a hole diameter of 100 μm is set at 2 mJ per shot. The copper foil on the surface where the hole is to be formed is removed by etching in advance, and the hole is formed while the resin layer is exposed.

Evaluation method of the amount of warpage by the reflow process: A copper foil of a FR-4 grade double-sided copper-clad laminate (copper foil thickness: 35 μm) having a substrate thickness of 0.2 mm was subjected to a surface treatment (blackening treatment). This was used as a substrate for the inner layer. The resin layer surface exposed by peeling off the cover film of the resin-coated copper foil prepared as described above is superposed on both surfaces of the inner layer substrate, and 17
While heating at 0 ° C. for 90 minutes, pressure was applied at 2.94 MPa to integrate the inner layer substrate and the two resin-coated copper foils. Then, on both surfaces of the obtained substrate, a resin layer surface exposed by peeling off the cover film of the resin-coated copper foil prepared as described above is overlapped, and heated at 170 ° C. for 90 minutes.
2. Pressed at 94MPa and integrated into 150m size
A multilayer printed wiring board for evaluation of warpage of mx 150 mm was produced. However, in Comparative Examples 1 to 3, a resin-coated copper foil without a cover film was used, and in Comparative Example 3, the carrier copper foil was peeled and removed after being integrated to produce a multilayer printed wiring board for warpage evaluation. did. The multilayer printed wiring board for evaluating the warpage was subjected to a reflow process of 230.
A process of exposing to an atmosphere of 10 ° C. for 10 seconds is performed, and the amount of warpage is evaluated. The amount of warpage was measured by measuring the maximum amount of lifting when a multilayer printed wiring board for evaluation of warpage having a size of 150 mm × 150 mm was placed on a horizontal board.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

As is evident from the results shown in Tables 1 to 3, in the examples of the present invention, the elastic modulus of the cured resin layer is higher and the amount of warpage due to the reflow process is smaller than in the comparative example. . Also, the pattern accuracy of the outer layer circuit is better than that of Comparative Example 1.

[0039]

According to the metal foil with resin of the invention according to claims 1 to 6, the resin layer is provided with a woven fabric or a non-woven fabric. According to this method, it is possible to obtain a multilayer printed wiring board in which the elastic modulus of a multilayer printed wiring board manufactured using the same can be increased, and the occurrence of warpage and deflection during reflow of component mounting can be reduced.

The metal foil with resin of the invention according to claim 2 is
The above claim 1 because the thickness of the metal foil is 9 μm or less.
In addition to the effects of the metal foil with resin of the invention according to the sixth to sixth aspects, a useful effect that a wrinkle or the like hardly occurs during handling and a metal foil with resin from which a fine circuit can be easily formed is obtained.

The multilayer printed wiring board of the invention according to claim 7 is manufactured by using the metal foil with resin according to any one of claims 1 to 6, so that it has a high elastic modulus and reflow of component mounting. It becomes a multilayer printed wiring board in which the occurrence of warpage and deflection is reduced.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoki Morita 1048 Kadoma Kadoma, Osaka Pref.Matsushita Electric Works, Ltd. (72) Inventor Miku Sugawa 1048, Kazuma, Kadoma, Osaka Prefecture F-term in Matsushita Electric Works, Ltd.

Claims (7)

[Claims] 1. A resin-attached metal foil formed by providing a heat-fusible and thermosetting resin layer on one side of a metal foil, wherein the resin layer comprises a woven or nonwoven fabric. Metal foil with resin. 2. The metal foil with resin according to claim 1, wherein the thickness of the metal foil is 9 μm or less. 3. The resin-attached metal foil according to claim 1, wherein the woven cloth provided in the resin layer is a glass cloth. 4. The resin-attached metal foil according to claim 1, wherein the nonwoven fabric provided in the resin layer is an organic fiber nonwoven fabric. 5. The resin-attached metal foil according to claim 1, wherein the cured product of the resin layer has a dielectric constant of 5 or less. 6. The metal foil with resin according to claim 1, wherein the thickness of the resin layer is 30 to 200 μm. 7. A resin layer side of the resin-attached metal foil according to any one of claims 1 to 6, which is manufactured through a step of laminating and laminating the resin layer side with an inner layer substrate forming a conductor circuit. A multilayer printed wiring board.