JP6645033B2 - Manufacturing method of metal-clad laminate, metal-clad laminate and printed wiring board - Google Patents

Description

  The present invention relates to a method for manufacturing a metal-clad laminate, a metal-clad laminate, and a printed wiring board.

  Conventionally, as a method for manufacturing a metal-clad laminate used for a printed wiring board, a fibrous base material is impregnated or coated with a thermosetting resin, and the thermosetting resin is semi-cured by heating or the like (B-stage). A plurality of prepregs produced by stacking are stacked so as to have a predetermined thickness, metal foils are arranged on one or both sides thereof, these are mainly sandwiched by stainless steel end plates, and a predetermined stage is set until a C-stage state is obtained by a multi-stage molding press. A method is employed in which molding is performed by applying time, temperature, and pressure. In the manufacturing method, usually, the outer surface of the head plate (that is, the metal foil) is used for the purpose of equalizing the pressure distribution, reducing the effect of the unevenness of the hot platen, and adjusting the heating rate during heating and compression. On the other side), a cushion material is arranged (see Patent Document 1).

JP 2008-307886 A

However, as described in Patent Document 1, a metal-clad laminate obtained by sandwiching and heating and compressing a hot plate with a configuration of “cushion material / end plate / metal foil / prepreg / metal foil / end plate / cushion material” In the molding step of performing heat compression, elongation or shrinkage occurs due to softening, melting or curing of the resin in the prepreg. On the other hand, the end plate and the cushion material also undergo elongation or contraction specific to the material. At this time, it was found that the elongation and shrinkage caused by the compression during molding remained as distortion inside the laminate. This distortion is called residual distortion. The residual strain is released as a result of, for example, etching or heating in the wiring board processing step and appears as a warp, resulting in a problem that transportability, adhesion, positional accuracy, and the like are reduced.
An object of the present invention is to solve the above problems and provide a method for manufacturing a metal-clad laminate having a small amount of warpage even after cooling to a high temperature (for example, 200 to 300 ° C.). An object of the present invention is to provide a metal-clad laminate obtained and to provide a printed wiring board formed by forming a wiring pattern on the metal-clad laminate.

  As a result of study by the present inventors, it has been found that the above problem can be solved by setting the difference between the heat shrinkage coefficients of the head plate and the cushion material within a specific range. The present invention has been completed based on such findings.

The present invention relates to the following [1] to [9].
[1] A structure (A) in which a metal foil is arranged on one or both sides of one prepreg or a prepreg obtained by laminating two or more prepregs, and end plates are arranged so as to sandwich both sides of the prepreg on which the metal foil is arranged. ), And after a cushion material is arranged outside the structure (A) or outside the structure (A ′) in which two or more of the structures (A) are overlapped and arranged, 150 to 250 is used by a hot platen. A method for producing a metal-clad laminate by heating and compressing at a temperature of 2 ° C. and 2 to 5 MPa, wherein the method satisfies the following condition (1).
Condition (1): The difference between the thermal contraction coefficient of the cushion material and the thermal contraction coefficient of the head plate adjacent to the cushion material is 5 ppm / ° C. or less.
[2] The method for producing a metal-clad laminate according to the above [1], wherein the material of the end plate is stainless steel.
[3] The method for producing a metal-clad laminate according to the above [1] or [2], wherein a difference between a thermal shrinkage coefficient in a longitudinal direction and a thermal shrinkage coefficient in a lateral direction of the cushion material is 12 ppm / ° C. or less.
[4] The method for producing a metal-clad laminate according to any one of [1] to [3], wherein the heat shrinkage coefficient of the end plate is 8 to 14 ppm / ° C.
[5] The method for producing a metal-clad laminate according to the above [4], wherein the cushion material is linter paper.
[6] The method for producing a metal-clad laminate according to any one of [1] to [3], wherein the heat shrinkage coefficient of the end plate is 8 to 24 ppm / ° C.
[7] The method for producing a metal-clad laminate according to the above [6], wherein the cushion material is kraft paper.
[8] A metal-clad laminate obtained by the production method according to any one of [1] to [7].
[9] A printed wiring board formed by forming a wiring pattern on the metal-clad laminate according to the above [8].

  According to the present invention, a metal-clad laminate having a small amount of warpage, that is, a metal-clad laminate having a small residual strain, even after being heated to a high temperature (for example, 200 to 300 ° C., more specifically 230 to 270 ° C.) and then cooled. A method of manufacturing can be provided. Further, a metal-clad laminate having a small amount of warpage can be obtained by the manufacturing method. Further, a printed wiring board formed by forming a wiring pattern on the metal-clad laminate can be provided.

It is the schematic which shows an example of the material arrangement | positioning between hot plates in the manufacturing method of the metal-clad laminated board in this invention.

First, an embodiment of the present invention will be described with reference to FIG.
The present invention arranges a metal foil [2] on one side or both sides of one prepreg [1] or a prepreg [1] in which two or more prepregs are overlapped, and sandwiches both sides of the prepreg on which the metal foil is arranged. A mirror plate [3] is disposed on the surface of the substrate to form a structure (A), and outside the structure (A) or outside the structure (A ') in which two or more structures (A) are superposed. This is a method for producing a metal-clad laminate by arranging a cushion material [4] and then heating and compressing it with a hot platen [6] at 150 to 250 ° C. and 2 to 5 MPa, satisfying the following condition (1). This is a method for manufacturing a metal-clad laminate. Usually, a carrier plate [5] is provided outside the cushion material [4]. The carrier plate [5] is for transporting the component (A) or the component (A ') and inserting and removing the component (A) into and from the molding apparatus.
Condition (1): The difference between the thermal contraction coefficient of the cushion material and the thermal contraction coefficient of the head plate adjacent to the cushion material is 5 ppm / ° C. or less. The heat shrinkage coefficient is measured according to the following conditions.
(Measurement condition of heat shrinkage coefficient)
Measuring device: Thermo-mechanical measuring device "TMA2940" (TA Instruments Japan Co., Ltd.)
Measurement mode: Tensile mode Measurement condition: 30 ° C. → 250 ° C. → 30 ° C.
Load: 0.2N
Atmosphere: Air atmosphere The heat shrinkage coefficient in this specification is obtained by the above method unless otherwise specified.

(About condition (1))
According to the study of the present inventors, when the difference between the heat shrinkage coefficient of the cushion material and the heat shrinkage coefficient of the head plate adjacent to the cushion material is set to 5 ppm / ° C. or less, the heat shrinkage which causes warpage is caused. It has been found that the residual strain inside the laminate accumulated in the laminate is significantly reduced. On the other hand, if this difference exceeds 5 ppm / ° C., the warpage of the laminate will increase significantly. From this viewpoint, the difference between the thermal contraction coefficient of the cushion material and the thermal contraction coefficient of the head plate adjacent to the cushion material may be 4 ppm / ° C. or less, or may be 3.5 ppm / ° C. or less.
The lower limit of the difference between the thermal contraction coefficient of the cushion material and the thermal contraction coefficient of the head plate adjacent to the cushion material is not particularly limited, but may be 0.5 ppm / ° C. or 1 ppm / ° C. May be 1.5 ppm / ° C. or 2 ppm / ° C.

(End plate)
As the end plate, a known end plate that can be used in the production of a laminated plate can be used. Examples of the mirror plate include a metal plate, a plastic plate, a glass plate, and a ceramic plate. Among these, a metal plate may be selected. As the metal of the metal plate, for example, a martensitic stainless steel, an austenitic stainless steel, a ferritic stainless steel, an austenite-ferrite (two-phase) from the viewpoint of keeping the coefficient of thermal contraction with the cushion material within the above range. Stainless steel such as stainless steel and precipitation hardening stainless steel; iron-nickel alloys such as 42 alloy; carbon steel such as low carbon steel, medium carbon steel, and high carbon steel; nickel steel; brass; Among these, from the viewpoint of reducing the amount of warpage, stainless steel may be selected as the metal of the metal plate, and austenitic stainless steel or precipitation hardening stainless steel may be selected. Examples of the austenitic stainless steel include SUS301, SUS304, and SUS304L. Examples of the precipitation hardening stainless steel include SUS420, SUS630, and SUS631J1. SUS301 and SUS630 may be selected as the metal of the metal plate. The heat shrinkage coefficient of the head plate may be 8 to 24 ppm / ° C, may be 8 to 14 ppm / ° C, may be 10 to 24 ppm / ° C, and may be 10 to 20 ppm / ° C. It may be 14 to 20 ppm / ° C. The heat shrinkage coefficient of the SUS630 is 11 ppm / ° C., and the heat shrinkage coefficient of the SUS 301 is 17 ppm / ° C.
Since austenitic stainless steel contains nickel, the austenitic structure is stable even at room temperature, and the content of chromium and nickel is high, so that it is excellent in corrosion resistance and heat resistance. The precipitation hardening stainless steel has been hardened by heat treatment.
In particular, the end plate adjacent to the cushioning material may be selected from the options described above. On the other hand, there is no particular limitation on the end plate that is not adjacent to the cushion material, but from the viewpoint of reducing the amount of warpage, it may be a stainless steel end plate or may be the same as the end plate adjacent to the cushion material.
The thickness of the head plate is not particularly limited, but may be generally 0.2 to 5 mm, 0.5 to 3 mm, or 1 to 2 mm.

(Cushion material)
The cushioning material has the effect of making the pressure distribution uniform and reducing the influence of the unevenness of the hot platen, and also makes it possible to adjust the heating rate during heating and compression.
During the heating and compression, elongation or shrinkage occurs due to softening, melting or hardening of the resin in the prepreg. On the other hand, elongation or shrinkage specific to the material of the head plate or cushion material also occurs. At this time, it has been found by the present inventors that the elongation or shrinkage due to the molding pressure causes distortion inside the laminate and remains. Therefore, it is important to select a cushion material, and the cushion material needs to satisfy the above condition (1). There is no particular limitation as long as the cushion material satisfies the condition (1). The thickness of the cushion material may be 200 to 800 μm or 300 to 600 μm from the viewpoint of workability and mechanical strength.
Examples of the cushion material include a rubber cushion material and a paper cushion material. Examples of the paper material of the paper cushioning material include wood; non-wood such as cotton, hemp, wood, bamboo, and straw. Among them, wood and cotton may be selected from the viewpoint of reducing the amount of warpage. In particular, the wood may be kraft pulp, and the cotton may be short fibers (linter). That is, a kraft paper cushion material or a linter paper cushion material may be selected as the paper cushion material. Here, "kraft paper" refers to paper that is not subjected to the bleaching step and is high in strength, out of paper made from pulp manufactured by the kraft method. In addition, the term "linter paper" refers to paper produced from cotton as a linter. It is.
Generally, a paper cushion material has a large difference in heat shrinkage coefficient in an in-plane vertical and horizontal direction (hereinafter, may be simply referred to as a direction) as compared with a head plate, particularly a stainless steel head plate. A linter paper cushion material having a small difference may be used. By using a linter paper cushion material having a small difference in the heat shrinkage coefficient depending on the direction, there is a tendency that the residual distortion caused by the heat compression is minimized and the warpage of the metal-clad laminate can be further reduced.
The difference in the thermal contraction coefficient between the longitudinal direction and the lateral direction of the cushion material may be 12 ppm / ° C or less, 10 ppm / ° C or less, 5 ppm / ° C or less, or 3 ppm / ° C or less. There may be. In the case of linter paper cushion material, the difference tends to be 3 ppm / ° C. or less. Here, the method of measuring the difference in the coefficient of thermal contraction in the in-plane longitudinal and lateral directions is as follows.
(Measurement method of difference in thermal contraction coefficient depending on in-plane vertical and horizontal directions)
The papermaking direction of the cushion material (one side arbitrarily selected when it is not possible to determine) is the vertical direction, and the 90-degree perpendicular direction is the horizontal direction. As the measurement sample, eight 16 mm × 5 mm samples are sampled at equal intervals on a diagonal line from a 1 m × 1 m sample. With respect to each sample, the coefficient of thermal contraction in the longitudinal direction and the coefficient of thermal contraction in the lateral direction are measured, and the difference therebetween is determined. The average value of the eight samples is defined as "difference in heat shrinkage coefficient depending on in-plane length and width directions".

(Prepreg)
The prepreg can be manufactured by impregnating or coating a sheet-like reinforcing substrate with a thermosetting resin composition, and semi-curing (B-stage) by heating or the like.
As the sheet-like reinforcing base material of the prepreg, well-known ones used for various kinds of laminates for electric insulating materials can be used. Examples of the material of the sheet-like reinforcing substrate include inorganic fibers such as glass fibers such as E glass, D glass, S glass, and Q glass; organic fibers such as polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. Among these, inorganic fibers or glass fibers may be used. These sheet-like reinforcing substrates have a shape such as a woven fabric, a nonwoven fabric, a roving, a chopped strand mat, or a surfacing mat. The material and shape are selected depending on the intended use and performance of the molded product, and one type may be used alone or two or more types and materials may be combined as needed.
Examples of the method of impregnating or applying the thermosetting resin composition to the sheet-like reinforcing substrate include a hot melt method and a solvent method.

The thickness of the sheet-shaped reinforcing substrate is not particularly limited, but may be 10 to 400 μm, 10 to 200 μm, or 50 to 150 μm.
The amount of the thermosetting resin composition adhered to the substrate is such that the resin content of the prepreg after drying (that is, the solid content derived from the thermosetting resin composition) is 20 to 90% by mass (20 to 70% by mass). And may be 30 to 60% by mass.), And then dried by heating at a temperature of usually 100 to 200 ° C. for 1 to 30 minutes. The prepreg of the present invention can be obtained by semi-curing (B stage).
As the prepreg, one sheet is used, or two or more sheets (may be 2 to 20 sheets) are overlapped and used.

The thermosetting resin composition contains a thermosetting resin. Examples of the thermosetting resin include an epoxy resin, a phenol resin, a polyimide resin, a polyester resin, a cyanate resin, a resin having a benzoxazine ring, and a thermosetting resin having a triazine ring. Among these, epoxy resins and phenol resins may be used.
Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, alkylphenol novolak epoxy resin, naphthol alkylphenol novolak epoxy resin, biphenyl epoxy resin, and aralkyl. Epoxy resin, naphthol epoxy resin, anthracene epoxy resin, dicyclopentadiene epoxy resin, naphthalene epoxy resin, biphenylaralkyl epoxy resin, fluorene epoxy resin, xanthene epoxy resin and the like. Among these, bisphenol A type epoxy resin may be used. The bisphenol A epoxy resin may be a brominated bisphenol A epoxy resin partially brominated.
The epoxy equivalent of the epoxy resin may be 100 to 500 g / eq, 120 to 400 g / eq, or 140 to 300 g / eq. Here, the epoxy equivalent is the mass (g / eq) of the resin per epoxy group, and can be measured according to the method specified in JIS K7236. Specifically, using an automatic titrator "GT-200" (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), weigh 2 g of the epoxy resin in a 200 ml beaker, drop 90 ml of methyl ethyl ketone, dissolve the ultrasonic cleaner, It is determined by adding 10 ml of glacial acetic acid and 1.5 g of cetyltrimethylammonium bromide, and titrating with a 0.1 mol / L perchloric acid / acetic acid solution.
The phenol resin may be a phenol novolak resin. The hydroxyl equivalent of the phenol resin may be 50 to 300 g / eq, 70 to 200 g / eq, or 70 to 150 g / eq.
As the thermosetting resin, one type may be used alone, or two or more types may be used in combination.
The content of the thermosetting resin in the thermosetting resin composition may be 40 to 90% by mass, may be 40 to 85% by mass, or may be 50 to 85% by mass, It may be 55 to 85% by mass.

The thermosetting resin composition may contain an inorganic filler, or may contain an inorganic filler. Examples of the inorganic filler include silica, alumina, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum borate, and barium titanate. Strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, calcium zirconate, and the like. Among these, aluminum hydroxide may be used.
One type of inorganic filler may be used alone, or two or more types may be used in combination.
The content of the inorganic filler in the thermosetting resin composition may be 0 to 300 parts by mass, or may be 20 to 150 parts by mass with respect to 100 parts by mass of the thermosetting resin, and may be 30 to 30 parts by mass. To 120 parts by mass, or 50 to 100 parts by mass.

The thermosetting resin composition may contain other additives such as a curing agent, a curing accelerator, a flame retardant, an antioxidant, an ultraviolet absorber, a photopolymerization initiator, a fluorescent whitening agent, an adhesion improver, and an organic compound. It may contain a filler and the like. These may be used alone or in combination of two or more. In particular, the thermosetting resin composition may contain a curing accelerator.
Examples of the curing accelerator, for example, an epoxy resin curing accelerator include imidazole compounds and derivatives thereof, organic phosphorus compounds, secondary amines, tertiary amines, and quaternary ammonium salts. Among these, imidazole compounds and derivatives thereof may be used. Specific examples of the imidazole compound and its derivative include, for example, 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, 2-ethyl -1-methylimidazole, 1,2-diethylimidazole, 1-ethyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 4-ethyl-2-methylimidazole, 2-phenyl-4-methylimidazole, 1 -Benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2- Phenyl- , 5-Dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo [1,2-a] benzimidazole, 2,4-diamino-6- [2 '-Methylimidazolyl- (1')] ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1 ')] ethyl-s-triazine, 2,4-diamino-6 Imidazole compounds such as-[2'-ethyl-4'-methylimidazolyl- (1 ')] ethyl-s-triazine; trimellitic acid adducts of the imidazole compounds; isocyanuric acid adducts of the imidazole compounds; And hydrobromic acid adducts. Among these, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole or 2-ethyl-4-methylimidazole may be used.
As the curing accelerator, one type may be used alone, or two or more types may be used in combination.
The content of the curing accelerator in the thermosetting resin composition may be 0 to 7 parts by mass, 0 to 5 parts by mass, and 0. The amount may be from 01 to 3 parts by mass, or from 0.05 to 1.5 parts by mass.

The thermosetting resin composition may contain an organic solvent to form a varnish from the viewpoint of facilitating handling by diluting and facilitating the production of a prepreg described below.
Examples of the organic solvent include, but not particularly limited to, alcohol solvents such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; Aromatic solvents such as toluene, xylene and mesitylene; Nitrogen atom-containing solvents including amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; Sulfoxide solvents such as dimethylsulfoxide Sulfur atom-containing solvents; examples include ester solvents including lactone solvents such as γ-butyrolactone.
Among them, from the viewpoint of solubility, alcohol solvents, ketone solvents, and nitrogen atom-containing solvents may be used, ketone solvents may be used, and methyl ethyl ketone may be used.
One organic solvent may be used alone, or two or more organic solvents may be used in combination.

The content of the organic solvent in the thermosetting resin composition may be appropriately adjusted to such an extent that the handling of the thermosetting resin composition is facilitated, and in particular, as long as the coating property of the varnish is good. Although there is no limitation, the solid content concentration (concentration of components other than the organic solvent) derived from the thermosetting resin composition may be 30 to 90% by mass, 40 to 80% by mass, or 50 to 90% by mass. It may be 80% by mass or 60 to 80% by mass.
The method of controlling the amount of the thermosetting resin composition (varnish) adhered to the sheet-like reinforcing substrate is not particularly limited, but, for example, a squeeze roll system, a cut bar system, or the like is generally employed. The adhesion amount of the thermosetting resin varnish to the sheet-like reinforcing base material is such that the content ratio of the solid content derived from the thermosetting resin composition is 35 with respect to the total amount of the thermosetting resin solid content and the sheet-like reinforcing base material. To 80% by mass, 35 to 60% by mass, or 40 to 60% by mass.

[Production method of metal-clad laminate]
A metal foil is arranged on one or both sides of one prepreg or a prepreg obtained by laminating two or more prepregs, and end plates are arranged so as to sandwich both sides of the prepreg on which the metal foil is arranged, as shown in FIG. The structure (A) is formed. In the present invention, a structure in which two or more of the constituents (A) are overlapped and arranged is referred to as a constituent (A ′).
The metal of the metal foil is not particularly limited as long as it can be used for forming a wiring pattern, but from the viewpoint of conductivity, copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, It may be titanium, chromium, or an alloy containing at least one of these metal elements, and may be copper, amylnium, or copper.
The thickness of the metal foil varies depending on the application, but is usually 3 to 100 μm, 3 to 50 μm, 3 to 30 μm, or 5 to 20 μm.
After arranging the cushion material on the outside of the component (A) or the component (A ′), the heating may be performed for 0.5 to 4 hours at 150 to 250 ° C. and 2 to 5 MPa using a hot plate, A metal-clad laminate is manufactured by heating and compressing. The heating temperature may be 160 to 220 ° C, or may be 160 to 200 ° C. The pressure may be between 3 and 5 MPa. The pressing method is not particularly limited, and a multi-stage pressing method may be used. When the heating and compression are completed, depressurizing and cooling may be performed.
As described above, a metal-clad laminate with a reduced amount of warpage is obtained.

  The wiring board of the present invention is obtained by forming a wiring pattern on the metal-clad laminate of the present invention. The method of forming the wiring pattern is not particularly limited. For example, a subtractive method, a full additive method, a semi-additive method (SAP) or a modified semi-additive method (m-SAP) is used. The wiring pattern can be formed by a known method such as Process.

  Hereinafter, the present invention will be described with reference to examples. Note that the present invention is not limited to these examples.

[Measurement method and conditions]
In each example and comparative example, each measurement was performed by the following method.
(A. Measurement conditions of heat shrinkage coefficient)
Measuring device: Thermo-mechanical measuring device "TMA2940" (TA Instruments Japan Co., Ltd.)
Measurement mode: Tensile mode Measurement condition: 30 ° C. → 250 ° C. → 30 ° C.
Load: 0.2N
Atmosphere: Air atmosphere (B. Method for measuring difference in heat shrinkage coefficient depending on in-plane vertical and horizontal directions)
The papermaking direction of the cushioning material (one side arbitrarily selected when it is not possible to determine) is the vertical direction, and the 90-degree perpendicular direction is the horizontal direction. As measurement samples, eight samples of 16 mm × 5 mm were taken at equal intervals on a diagonal line from a sample of 1 m × 1 m. For each sample, A. According to the measurement conditions, the heat shrinkage coefficient in the vertical direction and the heat shrinkage coefficient in the horizontal direction were measured, and the difference between them was obtained. The average value of the eight samples was defined as "difference in heat shrinkage coefficient depending on in-plane vertical and horizontal directions".

(C. Method of measuring warpage amount)
A test sample of 500 mm square was cut out from the metal-clad laminate manufactured in each example, and the amount of warpage of the sample was measured by a shadow moire method using “Thermoray PS200” manufactured by AKROMETRIX according to the following conditions.
Measurement area: 36mm x 36mm
Measurement conditions: The amount of warpage when heating from room temperature to 260 ° C. and then cooling to 50 ° C. was measured.

[Example 1]
100 parts by mass of brominated bisphenol A type epoxy resin "Epicoat 5046" (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 475 / eq), phenol novolak resin "Epicoat 154" (manufactured by Mitsubishi Chemical Corporation, hydroxyl equivalent: 178 g / eq) 54 parts by mass, 120 parts by mass of aluminum hydroxide, and 0.2 parts by mass of 2-ethyl-4-methylimidazole as a curing accelerator are dissolved in methyl ethyl ketone, and a thermosetting resin composition having a solid concentration of 70% by mass (varnish) ) Was prepared.
The thermosetting resin composition is impregnated onto a glass cloth woven cloth having a thickness of 0.10 mm, and then B-staged by heating and drying at 140 ° C. for 3 to 4 minutes to obtain a solid derived from the thermosetting resin composition. A prepreg having a content of 45% by mass was produced. Similarly, a total of four prepregs were produced.
Four pieces of the obtained prepregs are overlapped, copper foil having a thickness of 12 μm is arranged on both sides, and a stainless steel end plate “SUS630” having a thickness of 1.5 mm (heat shrinkage coefficient 11 ppm / ° C., heat shrinkage in in-plane vertical and horizontal directions) (A difference in coefficient of 1 ppm / ° C. or less) to constitute one set of constituent members.
Fifteen sets of the same components were prepared and superimposed on each other, and lintered paper cushion material “AACP” (heat shrinkage coefficient 8 ppm / ° C, difference in heat shrinkage coefficient 2 mm / ° C depending on in-plane length and width directions, Awa Paper Co., Ltd.) (Manufactured by a company), and further, a carrier plate is arranged on both outer sides thereof. Then, the carrier plate is inserted between the hot plates, and is heated and compressed at 185 ° C. and 4 MPa for 85 minutes by a multi-stage pressurizing method. A double-sided copper-clad laminate was produced.
Among the obtained double-sided copper-clad laminates, a double-sided copper-clad laminate prepared from the structure in contact with the cushion material and a structure next to (one inside) the structure in contact with the cushion material The warpage of the double-sided copper-clad laminate was measured according to the method described above. Table 1 shows the results.

[Example 2]
In Example 1, instead of the stainless steel end plate "SUS630", a stainless steel end plate "SUS301" (heat shrinkage coefficient: 17 ppm / ° C, difference in heat shrinkage coefficient in the longitudinal and transverse directions of the plane: 1 ppm / ° C or less) was used, and linter paper cushion material was used. The same except that kraft paper cushion material “KS-190” (heat shrinkage coefficient 20 ppm / ° C., difference in heat shrinkage coefficient according to in-plane vertical and horizontal directions 9 ppm / ° C., manufactured by Oji Paper Co., Ltd.) was used instead of “AACP” To prepare a double-sided copper-clad laminate, and the amount of warpage was measured in the same manner. Table 1 shows the results.

[Comparative Example 1]
In Example 1, instead of the linter paper cushion material "AACP", a kraft paper cushion material "KS-190" (heat shrinkage coefficient 20 ppm / ° C, difference in heat shrinkage coefficient depending on in-plane longitudinal and transverse directions 9 ppm / ° C, Oji Paper Co., Ltd.) Was used to produce a double-sided copper-clad laminate, and the amount of warpage was measured in the same manner. Table 1 shows the results.

  From Table 1, in comparison with Comparative Example 1, in Examples 1 and 2, the double-sided copper-clad laminate produced from the structure that was in contact with the cushion material was heated to the temperature described in the “method for measuring warpage”. However, even in the double-sided copper-clad laminate obtained by releasing the residual strain, the amount of warpage was extremely small. In other words, it can be said that the residual distortion of the outermost laminated plate produced by heating and compression can be minimized by the production method of the present invention. In Comparative Example 1, it can be seen that not only the amount of warpage of the double-sided copper-clad laminate produced from the structure in contact with the cushion material was large, but also the amount of warpage in the plane was large.

  Since the metal-clad laminate obtained by the production method of the present invention has a small amount of warpage, it is useful for producing a wiring board for electronic equipment.

1: Pre-preg 2: Metal foil 3: End plate 4: Cushion material 5: Carrier plate 6: Press hot plate 10: Constructed body (A)
11: Construct body (A ')

Claims (4)

A metal foil is disposed on one or both sides of one prepreg or a prepreg obtained by laminating two or more prepregs, and a head plate having a heat shrinkage coefficient of 8 to 14 ppm / ° C. is disposed so as to sandwich both sides of the prepreg on which the metal foil is disposed. After the cushioning material is disposed outside the structure (A) or the structure (A ′) in which two or more of the structures (A) are superposed and arranged, A method for producing a metal-clad laminate by heating and compressing at 150 to 250 ° C. and 2 to 5 MPa using a hot plate, wherein the following condition (1) is satisfied, and the longitudinal length of the cushion material is measured according to the following method B: A method for producing a metal-clad laminate, wherein the difference between the heat shrinkage coefficient in the transverse direction and that in the transverse direction is 12 ppm / ° C or less.
Condition (1): The difference between the heat shrinkage coefficient of the cushion material and the heat shrinkage coefficient of the head plate adjacent to the cushion material measured according to the following measurement condition A is 5 ppm / ° C. or less.
(A. Measurement conditions of heat shrinkage coefficient)
Measuring device: Thermomechanical measuring device Measuring mode: Tensile mode Measuring condition: 30 ° C → 250 ° C → 30 ° C
Load: 0.2N
Atmosphere: Air atmosphere (B. Measuring method of difference in thermal shrinkage coefficient depending on in-plane vertical and horizontal directions of cushion material)
The papermaking direction of the cushioning material (one side arbitrarily selected when it is not possible to determine) is the vertical direction, and the 90-degree perpendicular direction is the horizontal direction. Measurement sample from a sample of the vertical 1 m × horizontal 1 m, the sample of longitudinal 16 mm × horizontal 5mm to eight sampled at equal intervals in a diagonal. For each sample, according to the measurement conditions of the A, longitudinal thermal contraction coefficient and lateral thermal contraction coefficient was measured, Ru seek their difference. The average value of the eight samples is defined as the difference in the coefficient of thermal contraction in the in-plane vertical and horizontal directions.   The method for manufacturing a metal-clad laminate according to claim 1, wherein the material of the end plate is stainless steel.   The method for producing a metal-clad laminate according to claim 1 or 2, wherein a difference between a thermal shrinkage coefficient in a longitudinal direction and a thermal shrinkage coefficient in a lateral direction of the cushion material is 3 ppm / ° C or less. The method for producing a metal-clad laminate according to any one of claims 1 to 3 , wherein the cushion material is linter paper.