JP2006224587A - Manufacturing process of metal foil stretched laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process of a metal foil stretched laminate excellent in warp characteristics for obtaining a printed-wiring board with a little warp in a working procedure and also after the working procedure. <P>SOLUTION: The manufacturing process of a metal foil stretched laminate comprises: superimposing a metal foil onto a prepreg in which a thermosetting resin composition is impregnated into a glass cloth with a thickness of 20-200 μm; and adding heat and pressure to manufacture a metal foil stretched laminate, wherein the prepreg elongation percentage expressed in the following equation of the above prepreg is not more than 0.3%. The prepreg elongation percentage = (prepreg size - prepreg size of resin elimination)/prepreg size of resin elimination ×100%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a metal foil-clad laminate used for electrical / electronic devices and the like.

  Conventional printed multilayer wiring boards made of metal foil-clad laminates are made by, for example, impregnating a base material such as glass cloth with a thermosetting resin composition such as an epoxy resin composition, followed by heat drying and semi-curing (B stage The prepreg is prepared by stacking the required number of prepregs, and a metal foil such as a copper foil is laminated on one side or both sides thereof, and is laminated by heating and pressing to form a metal foil-clad laminate. Is made. And after etching the metal foil on the surface of the metal foil-clad laminate to produce a guide mark used on the surface for producing a conductor circuit and a printed wiring board, an inner layer substrate is produced, and then a roughening treatment is performed as necessary. Then, on the inner layer substrate on which the conductor circuit and the like are formed, the required number of prepregs produced in the same manner as described above are stacked on one side or both sides, and a metal foil is disposed on one side or both sides as necessary. Manufacture is performed by laminating and molding by heating and pressing.

With the recent increase in density of electronic devices and printed wiring boards, high quality and high reliability of metal foil-clad laminates that are used as the materials is required.
Warpage is one of the quality requirements for metal foil-clad laminates, and warpage can cause troubles during the process of processing printed wiring boards or lower connection reliability after mounting. Small materials are desired.

  As means for improving warpage, various methods such as adjusting the number of driven glass cloths as disclosed in Patent Document 1 have been studied.

JP-A-10-272733

  An object of the present invention is to provide a method for producing a metal foil-clad laminate having excellent warpage characteristics to obtain a printed wiring board having a small warp during and after the processing step.

As a result of investigations to solve the above problems, it has been clarified that the strain remaining in the prepreg has a great influence on the warpage of the subsequent processing steps. That is, the prepreg is generally manufactured by a coating machine comprising a resin impregnation and drying process. At this time, mainly in the case of a vertical dryer, the height of the drying furnace and the tension applied to the glass cloth are used. Remains as strain in the prepreg and appears as a warp in the processing step.
Furthermore, as a result of examining a method for evaluating the residual strain, the residual strain can be expressed as the size of the prepreg and the dimensional change rate after removing the resin of the prepreg (hereinafter referred to as the elongation rate). The present inventors have found that warp characteristics are excellent by using a prepreg having an elongation of 0.3% or less.

That is, the present invention is a metal foil-clad laminate obtained by superposing a metal foil with a prepreg impregnated with a thermosetting resin composition on a glass cloth having a thickness of 20 to 200 μm, and then applying the following formula of the prepreg. The present invention relates to a method for producing a metal foil-clad laminate, wherein the prepreg elongation rate is within 0.3%.

  The metal-clad laminate according to the present invention can provide a metal-clad laminate having excellent warpage characteristics when a prepreg having an elongation of 0.3% or less is applied to the substrate used for the metal-clad laminate.

  The metal-clad laminate according to the present invention is a laminate of a prepreg, a metal foil, and a metal foil obtained by impregnating a thermosetting resin composition into a glass cloth having a thickness of 20 to 200 μm and then curing the glass cloth. And heated and pressurized.

  The glass cloth used in the present invention is limited to a glass cloth having a thickness of 20 to 200 μm. When the thickness of the glass cloth is less than 20 μm, the single yarn used for the production of the glass cloth becomes thin, and the production of the glass cloth becomes difficult. Moreover, when the thickness of the glass cloth exceeds 200 μm, it is difficult to impregnate the resin uniformly in the prepreg surface and in the thickness direction, and the warp characteristics and the like are poor.

  In the glass cloth used in the present invention, both the warp and the weft are preferably yarns stipulated in IPC standard 4412. When this yarn is used to produce a plain weave glass cloth having a thickness of 20 to 200 μm, the ratio of the thermosetting resin composition impregnated into the glass cloth can be produced in an appropriate range for molding.

  As the thermosetting resin composition used in the present invention, the thermosetting resin composition used for the production of the metal foil-clad laminate is epoxy resin type, phenol resin type, polyimide resin type, unsaturated polyester resin type, polyphenylene. Thermosetting resins in general, such as ether resins alone, modified products, and mixtures, can be used.

  The thermosetting resin composition contains a thermosetting resin as an essential component, and can contain a curing agent, a curing accelerator, an inorganic filler, a solvent, and the like of the thermosetting resin as necessary. . Note that a thermosetting resin with low self-curing property such as an epoxy resin needs to contain a curing agent for curing the resin.

  In addition, when a thermosetting resin composition is an epoxy resin type | system | group, the balance of an electrical property and adhesiveness is favorable and preferable. Examples of the epoxy resin contained in the epoxy resin-based resin composition include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, bisphenol A novolac type epoxy resin, and bisphenol F novolak. Type epoxy resin, cresol novolac type epoxy resin, diaminodiphenylmethane type epoxy resin, and epoxy resin flame-retardant by halogenating a part of hydrogen atoms in these epoxy resin structures. Examples of the curing agent contained in the epoxy resin-based resin composition include amide-based curing agents such as dicyandiamide and aliphatic polyamide, amine-based curing agents such as ammonia, triethylamine, and diethylamine, phenol novolac resins, and cresols. Examples thereof include phenolic curing agents such as novolak resin and p-xylene-novolak resin, and acid anhydrides.

  The inorganic filler that can be contained in the thermosetting resin composition includes inorganic powder fillers such as silica, calcium carbonate, aluminum hydroxide, and talc, glass fibers, pulp fibers, synthetic fibers, and ceramic fibers. Examples of the solvent that can be contained in the thermosetting resin composition include amides such as N, N-dimethylformamide, ethers such as ethylene glycol monomethyl ether, acetone, Examples thereof include ketones such as methyl ethyl ketone, alcohols such as methanol and ethanol, and aromatic hydrocarbons such as benzene and toluene.

  The method for impregnating the glass cloth with this thermosetting resin composition is not particularly limited, but it is desirable to have an apparatus for controlling the tensile tension applied to the glass cloth. In addition, after impregnating a thermosetting resin composition into a glass cloth, a general prepreg obtained by heating and drying to obtain a B-stage is obtained.

  As the metal foil used in the present invention, copper, aluminum, brass, nickel, etc. can be used alone, alloy, composite metal foil, a single-sided metal-clad laminate in which metal foil is laminated and formed instead of metal foil, A double-sided metal-clad laminate can also be used. In addition, this metal foil is not limited to use only for preparation of a metal foil-clad laminate, and may be used by being laminated on one side or both sides of the laminate obtained by laminating an inner layer substrate and a prepreg. The thickness of the metal foil is generally 0.003 to 0.070 mm when used for producing a metal foil-clad laminate.

  As conditions for heating and pressurizing when producing a metal foil-clad laminate, the thermosetting resin composition may be appropriately adjusted and heated and pressurized under the conditions for curing, but if the pressurization pressure is high, the conductor circuit Since variation in dimensional shrinkage may become large, it is preferable to apply pressure at as low a pressure as possible within a range that satisfies the moldability. Note that it is preferable to perform heating and pressing in a reduced-pressure atmosphere of 300 Torr or less because moldability without generation of voids is improved.

  The method for etching the metal foil on the surface of the metal foil-clad laminate is not particularly limited, and a general method can be applied depending on the metal foil and the etching resist used for the etching.

Example 1
The base material was 2116 glass cloth specified in IPC-4412.

As the thermosetting resin composition, an epoxy resin resin composition composed of the following two epoxy resins, a curing agent, a curing accelerator, and two solvents was used.
-Epoxy resin 1: 87.5 parts by weight of tetrabromobisphenol A type epoxy resin [trade name YDB-500, manufactured by Toto Kasei Co., Ltd.]-Epoxy resin 2: Cresol novolac type epoxy resin [product, manufactured by Toto Kasei Co. 12.5 parts by weight of solid name YDCN-220], curing agent: 2.8 parts by weight of dicyandiamide, curing accelerator: 0.18 parts by weight of 2-ethyl-4-methylimidazole, solvent: N, N -25 parts by weight of dimethylformamide.
Solvent 2: 100 parts by weight of methyl ethyl ketone.

  Using the vertical coating machine, the amount of the thermosetting resin composition after drying the resin composition is 100 parts by weight based on the total of the thermosetting resin composition and the glass cloth. After adjusting and impregnating to 55 parts by weight, it was dried at a maximum temperature of 185 ° C. to prepare a prepreg having a thickness of 0.10 mm.

  At this time, coating was performed with a tension of 15 kg in the glass cloth vertical direction, and a prepreg having an elongation rate of 0.3% was obtained. The elongation is measured at room temperature.

  After laminating and laminating a copper foil having a thickness of 12 μm on both sides of the prepreg, the laminate was sandwiched between metal plates, and heated and pressure-molded at a maximum temperature of 180 ° C. and a pressure of 3.0 MPa for 90 minutes. A copper-clad laminate was produced.

(Comparative Example 1)
A 0.1 mm double-sided copper-clad laminate was obtained in the same manner as in Example 1, except that 35 kg of tension was applied in the glass cloth vertical direction to obtain a prepreg having an elongation of 0.8%.

(Comparative Example 2)
A 0.1 mm double-sided copper-clad laminate was obtained in the same manner as in Example 1 except that 45 kg of tension was applied in the glass cloth vertical direction to obtain a prepreg having an elongation rate of 1.2%.

(Evaluation results)
Warpage characteristics and dimensional characteristics of the metal-clad laminates obtained in Examples 1-2 and Comparative Examples 1-2 were evaluated.

  As a result, as shown in Table 1, it was confirmed that the warpage and dimensional characteristics of the example were improved as compared with Comparative Examples 1 and 2.

Claims (1)

In a metal foil-clad laminate obtained by superposing a metal foil with a prepreg impregnated with a thermosetting resin composition on a glass cloth having a thickness of 20 to 200 μm, the prepreg elongation represented by the following formula of the prepreg Is within 0.3%, a method for producing a metal foil-clad laminate.