JPH06328631A - Metal foil clad composite laminated sheet and printed wiring board - Google Patents

Abstract

(57) [Summary] [Object] To provide a metal foil-clad composite laminate having a small coefficient of thermal expansion, which is suitable as a substrate for a printed wiring board on which package components are surface-mounted. In a printed wiring board in which the insulating substrate is a composite laminated board, the solder connection reliability of the surface-mounted package component is increased. [Structure] An intermediate layer composed of a glass non-woven fabric substrate impregnated with a thermosetting resin and a surface layer made of a glass woven fabric substrate impregnated with a thermosetting resin, and an inorganic filler contained in the resin of the intermediate layer. The composite thermal expansion coefficient of the material is set to 15 ppm / ° C or less,
In addition, the volume fraction of the inorganic filler in the resin of the intermediate layer is 0.7
Set to 5 or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal foil-clad composite laminate and a printed wiring board suitable for a printed wiring board on which a package component having a low coefficient of thermal expansion is surface-mounted.

[0002]

2. Description of the Related Art In recent years, printed wiring boards used in electronic devices have been mounted with components in the direction of high-density surface mounting for high reliability and miniaturization of devices. This allows
The package parts to be mounted have a coefficient of thermal expansion of 14 ppm /
From 8 to 8 ppm / ° C, for example,
TSOP (Thin Small Outline Package) and TQFP
(Thin Quad Flat Package) etc. When the intermediate layer is a glass non-woven fabric substrate impregnated with a thermosetting resin, the surface layer is composed of a glass woven fabric substrate impregnated with a thermosetting resin, a metal foil-clad composite laminate is processed into a printed wiring board. The coefficient of thermal expansion in the plane direction is 20 ppm / ℃
It is a degree. This is because the volume fraction of the inorganic filler in the resin of the intermediate layer of the composite laminate is only in the range of 0.1 to 0.5. When the package component is surface-mounted on such a printed wiring board, the difference in the coefficient of thermal expansion between the package component and the printed wiring board increases,
Thermal stress is applied to the parts where the package parts are connected by soldering, and cracks are likely to occur.

[0003]

An object of the present invention is to provide a metal foil-clad composite laminate having a small coefficient of thermal expansion, which is suitable as a substrate for a printed wiring board on which package components are surface-mounted. . Further, in a printed wiring board in which the insulating substrate is a composite laminated board, it is to improve the solder connection reliability of the surface-mounted package component.

[0004]

In order to solve the above-mentioned problems, a metal foil-clad composite laminate according to the present invention comprises a glass nonwoven fabric substrate in which an intermediate layer is impregnated with a thermosetting resin, and a surface layer is a thermosetting resin. In a glass woven fabric substrate impregnated with a resin, the synthetic thermal expansion coefficient of the inorganic filler contained in the resin of the intermediate layer is 15 ppm / ° C. or less, and the volume of the inorganic filler in the resin of the intermediate layer is It is characterized in that the fraction is 0.75 or more. Further, the printed wiring board according to the present invention,
An intermediate layer composed of a glass non-woven fabric substrate impregnated with a thermosetting resin and a surface layer composed of a glass woven fabric substrate impregnated with a thermosetting resin, which is included in the resin of the intermediate layer. Synthetic thermal expansion coefficient of inorganic filler is 15p
pm / ° C. or less, and the volume fraction of the inorganic filler in the resin of the intermediate layer is 0.75 or more. In the present invention, as the inorganic filler, aluminum hydroxide, glass powder or the like may be used alone or as a mixture. When one type of inorganic filler is used alone, the synthetic thermal expansion coefficient is the thermal expansion coefficient of the inorganic filler itself. When two or more kinds of inorganic fillers are mixed and used, the synthetic thermal expansion coefficient is represented by the following (Equation 1).

[0005]

[Formula 1] Composite thermal expansion coefficient = α ₁ φ ₁ + α ₂ φ ₁ + --- + α _i φ _i + --- α _i : Thermal expansion coefficient of filler i φ _i : Filler _{i in} all fillers Volume fraction of

[0006]

The composite laminate is composed of a surface layer made of glass woven fabric as a base material and an intermediate layer made of glass nonwoven fabric as a base material. An inorganic filler is added for the purpose of holding. FIG. 1 shows the relationship between the synthetic thermal expansion coefficient of the inorganic filler and the thermal expansion coefficient of the composite laminate, with the volume fraction of the inorganic filler in the resin of the intermediate layer being constant (0.75). is there.
It can be seen that the thermal expansion coefficient of the composite laminate greatly changes when the synthetic thermal expansion coefficient of the inorganic filler is 15 ppm / ° C. Further, FIG. 2 shows that the composite thermal expansion coefficient of the inorganic filler in the resin of the intermediate layer is constant (15 ppm / ° C.), and the volume fraction of the inorganic filler in the resin of the intermediate layer and the thermal expansion of the composite laminated plate are set. It shows the relationship of the rates. It can be seen that the coefficient of thermal expansion of the composite laminate greatly changes when the volume fraction of the inorganic filler is 0.75. From the above,
The synthetic thermal expansion coefficient of the inorganic filler in the resin of the intermediate layer is 15 pp
It can be understood that the coefficient of thermal expansion of the composite laminate can be reduced by setting the volume ratio of the inorganic filler in the resin to 0.75 or more and m / ° C. or less.

[0007]

EXAMPLES The thermosetting resin used in the present invention is a commonly used one such as polybutadiene resin, epoxy resin, phenol resin, melamine resin, diallyl phthalate resin and silicon resin. From the viewpoint of workability of impregnation into a sheet-shaped substrate, it is preferable to use a low molecular weight resin that does not increase the viscosity of the resin varnish. In order to make the laminate flame-retardant, a flame retardant such as a bromine compound or a phosphorus compound may be added to the resin. A large amount of inorganic filler is added to the resin that impregnates the glass nonwoven fabric substrate that constitutes the intermediate layer of the composite laminate, but in order to suppress the sedimentation of the inorganic filler in the resin varnish, a dispersant or A thickener may be added. The glass non-woven fabric used in the present invention is usually used for electrical insulation using E glass, D glass or the like. Epoxy resin, poval, acrylonitrile, pulp and the like are used as a binder for binding glass fibers into a non-woven fabric. Further, the glass woven fabric used in the present invention is also one usually used for electrical insulation using E glass, D glass and the like. If the weave density of the glass woven cloth is high,
Since the coefficient of thermal expansion of the surface layer of the composite laminate becomes small, it is preferable to select one having a high weave density. The metal foil integrated on the surface of the composite laminate is copper foil, nickel foil, aluminum foil, or the like. Examples of the present invention will be described in detail together with comparative examples.

Example 1 100 g of an epoxy resin (“Ep-1001” manufactured by Yuka Shell Co., Ltd., an epoxy equivalent of 500) was added to 3 g of dicyandiamide and 2-ethyl 4-catalyst as a catalyst.
0.2 g of methylimidazole was uniformly dissolved to obtain a varnish (A). The varnish (A) is woven with glass cloth (190 g /
m ² ), and was dried to obtain a prepreg (A) having a resin content of 41% by weight. E glass powder (coefficient of thermal expansion: 6.4 ppm / ° C.) as an inorganic filler was added to the varnish (A) so that the volume fraction was 0.80 in terms of solid content. Further, a surfactant (“Marialim” manufactured by NOF Corporation, a compound having a polyoxyalkylene glycol and an acid anhydride structure in the skeleton) was added to a resin solid content of 1.00 to a volume fraction of 1.00.
01 was added to prepare a varnish (B1).
A glass nonwoven fabric (73 g / m ² ) was impregnated with the varnish (B1) and dried to obtain a prepreg (B1) having a resin content of 92% by weight including an inorganic filler. Prepreg (B1) 3
One sheet is used as an intermediate layer, prepreg (A) is placed on both surfaces, and copper foil (thickness 18 μm) is placed on both surfaces on the outermost surface.
A copper-clad laminate was obtained by laminating and molding at 70 ° C. and 40 kg / cm ² for 60 minutes.

Example 2 In Example 1, the inorganic filler was E glass powder and aluminum hydroxide (coefficient of thermal expansion of 15.
0 ppm / ° C.) (both volume fraction: E glass powder / aluminum hydroxide = 24.5 / 75.5, synthetic thermal expansion coefficient: 13.0 ppm / ° C.), and the inorganic filler is calculated as solid content. A varnish (B2) having a volume fraction of 0.82 was prepared.
The glass woven fabric was impregnated with the varnish (B2) and dried to obtain a prepreg sheet (B2) containing an inorganic filler and having a resin content of 93% by weight. Using the prepreg sheet (A) and the prepreg sheet (B2), lamination molding was performed in the same manner as in Example 1 to obtain a copper clad laminate.

(Example 3) In Example 1, aluminum hydroxide was used as the inorganic filler, and a varnish (B3) having a volume fraction of the inorganic filler of 0.75 in terms of solid content was prepared. The glass woven fabric was impregnated with the varnish (B3) and dried to obtain a prepreg sheet (B3) containing an inorganic filler and having a resin content of 93% by weight. Using the prepreg sheet (A) and the prepreg sheet (B3), lamination molding was performed in the same manner as in Example 1 to obtain a copper-clad laminate.

Comparative Example 1 In Example 1, the inorganic filler was aluminum hydroxide and talc (coefficient of thermal expansion: 20.0 p).
pm / ° C) mixture (both volume fraction: aluminum hydroxide / talc = 40/60, synthetic thermal expansion coefficient: 18.0 p)
pm / ° C.) to prepare a varnish (B4) having a volume fraction of the inorganic filler of 0.40 in terms of solid content. Varnish (B4)
Was impregnated into a glass nonwoven fabric and dried to obtain a prepreg sheet (B4) having a resin content of 90% by weight including an inorganic filler. Prepreg sheet (A), prepreg sheet (B
4) was used and laminated in the same manner as in Example 1 to obtain a copper-clad laminate.

Comparative Example 2 In Example 1, the inorganic filler was a mixture of aluminum hydroxide and talc (both volume fraction: aluminum hydroxide / talc = 40/60, synthetic thermal expansion coefficient: 18.0 ppm / ℃), and a varnish (B5) having a volume fraction of the inorganic filler of 0.82 in terms of solid content was prepared. Impregnate the glass woven fabric with varnish (B5), dry it,
A prepreg sheet (B5) containing an inorganic filler and having a resin content of 93% by weight was obtained. Using the prepreg sheet (A) and the prepreg sheet (B5), lamination molding was performed in the same manner as in Example 1 to obtain a copper-clad laminate.

Comparative Example 3 In Example 1, the inorganic filler was E glass powder, and a varnish (B6) having a volume fraction of the inorganic filler of 0.70 in terms of solid content was prepared. Varnish (B
6) A glass non-woven fabric is impregnated with and dried, and a prepreg sheet (B6) containing 93% by weight of a resin containing an inorganic filler.
Got Using the prepreg sheet (A) and the prepreg sheet (B6), lamination molding was performed in the same manner as in Example 1 to obtain a copper clad laminate.

The coefficient of thermal expansion of each of the copper-clad laminates and the result of evaluation of solder connection reliability when the copper-clad laminate is processed into a printed wiring board and an IC chip is soldered by a surface mounting method are shown. Shown in 1. The coefficient of thermal expansion is measured by the TMA method. Also, the solder connection reliability is -30 ° C.
・ A thermal cycle test was conducted for 1 hour and 150 ° C. for 1 hour, and the evaluation was made by the number of cycles until 1% of the samples resulted in poor conduction.

[0015]

[Table 1]

From Table 1, the synthetic thermal expansion coefficient of the inorganic filler in the resin of the intermediate layer of the composite laminate was set to 15 ppm / ° C. or less, and the volume fraction of the inorganic filler in the resin was 0.
It can be seen that when the ratio is 75 or more, the coefficient of thermal expansion of the composite laminated plate becomes small and the solder connection reliability of the surface-mounted IC chip becomes high.

[0017]

As described above, the laminate of the metal foil-clad composite according to the present invention has a small coefficient of thermal expansion in the plane direction and is suitable for a printed wiring board on which components are mounted by the surface mounting method. . Further, the printed wiring board according to the present invention has high reliability of the solder connection portion even if the component is mounted by the surface mounting method and the cooling / heating cycle is repeated.

[Brief description of drawings]

FIG. 1 shows the relationship between the synthetic thermal expansion coefficient of an inorganic filler and the thermal expansion coefficient of a composite laminate, with the volume fraction of the inorganic filler in the resin of the intermediate layer of the composite laminate being constant (0.75). It is the curve figure shown.

[Fig. 2] A composite thermal expansion coefficient of the inorganic filler in the resin of the intermediate layer of the composite laminate is kept constant (15 ppm / ° C),
FIG. 6 is a curve diagram showing the relationship between the volume fraction of the inorganic filler in the resin of the intermediate layer and the thermal expansion coefficient of the composite laminate.

Claims (2)

[Claims] 1. A metal foil-clad composite laminate comprising an intermediate layer made of a glass non-woven fabric substrate impregnated with a thermosetting resin and a surface layer made of a glass woven fabric substrate impregnated with a thermosetting resin. Is a metal foil covering characterized in that the synthetic thermal expansion coefficient of the inorganic filler contained in the resin is 15 ppm / ° C. or less and the volume fraction of the inorganic filler in the resin is 0.75 or more. Composite laminated board. 2. A printed wiring board in which an insulating substrate is composed of a composite laminated plate whose intermediate layer is a glass nonwoven fabric base material impregnated with a thermosetting resin and whose surface layer is a glass woven base material impregnated with a thermosetting resin. In the intermediate layer, the synthetic thermal expansion coefficient of the inorganic filler contained in the resin is 15 ppm / ° C. or less, and the volume fraction of the inorganic filler in the resin is 0.75 or more. And a printed wiring board.