JP2557325B2 - Multilayer copper clad laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a multilayer copper clad laminate having excellent drilling workability, measling resistance, and formability.

(Prior Art) With the recent increase in speed and density of industrial electronic devices,
The demand for multilayer printed wiring boards as wiring boards used in these electronic devices is increasing year by year. Conventionally, a general multilayer printed wiring board using a glass woven cloth is obtained by coating and impregnating a glass woven cloth (hereinafter also referred to as glass cloth) with an epoxy resin, followed by heating and drying to obtain a glass woven cloth base material prepreg.
After heating and pressing this together with the copper foil, the copper foil is laminated on the inner layer printed board on which the circuit is formed via the glass woven base material prepreg of the above and copper, and the heat and pressure are integrally molded to form a multilayer printed wiring board. It was manufactured.

However, the conventional prepreg used there uses a glass woven fabric as the base material, so the drilling workability during through-hole processing is poor, and as a result, inner wall roughness and smearing easily occur, and the drill blade It had the drawback of having a short life. To improve this, Japanese Patent Laid-Open No. 640009/1986
A method is known in which a glass nonwoven fabric is used as a base material and an epoxy resin as an impregnating resin contains an inorganic filler as in the disclosed technique of No. 4. However, even in this method, when a prepreg using a glass nonwoven fabric is manufactured, the inorganic filler is likely to settle in the resin varnish, and the glass nonwoven fabric itself has variations in the basis weight, which may cause impregnation failure and uneven coating. There is a drawback that. Furthermore, if there is poor prepreg impregnation or uneven coating, the fluidity will be poor during multilayer molding,
The multilayer printed circuit board using this prepreg has a drawback that voids are likely to remain in the vicinity of the inner layer circuit, and as a result, the measling resistance is lowered.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above problems and provides a multilayer copper clad laminate having no void formation, which is excellent in drilling processability, measling resistance, and formability. It is the one we are trying to provide.

[Structure of the Invention] (Means for Solving the Problems) As a result of intensive studies conducted by the present inventors to achieve the above-mentioned object, a glass nonwoven fabric containing an inorganic filler in papermaking is used as a base material. It was found that a multilayer copper clad laminate excellent in drilling processability, measling resistance and formability can be obtained by arranging the prepreg so as to be in contact with the circuit-formed inner layer plate, and has completed the present invention. . That is, the present invention is a multilayer copper clad laminate formed by superposing a plurality of prepregs and an outer layer copper foil on the front and back surfaces of an inner layer board on which a circuit is formed, and integrally molding by heating and pressing, and the plurality of prepregs. As a prepreg that contacts the inner layer plate of
A multilayer copper-clad laminate characterized by using a prepreg obtained by impregnating and drying a thermosetting resin in a non-woven fabric containing an inorganic filler, which has been compounded during papermaking.
Further, it is a multi-layered copper-clad laminate which uses an inorganic filler having an average particle diameter of 1 to 10 μm and is contained in an amount of 20 to 70% by weight based on the glass nonwoven fabric.

As the inorganic filler used in the present invention, any one having a good electric insulating property can be used. For example, E glass powder, aluminum hydroxide, magnesium hydroxide,
Alumina, magnesium oxide, titanium dioxide, calcium titanate, calcium silicate, aluminum silicate and the like can be mentioned, and these can be used alone or in admixture of two or more. The average particle size of this inorganic filler is preferably 1 to 10 μm. When the average particle diameter is less than 1 μm, it is difficult to adhere to the glass nonwoven fabric during papermaking, and when it exceeds 10 μm, sedimentation during papermaking is remarkable, which causes unevenness of papermaking of the glass nonwoven fabric, which is not preferable. The blending ratio of the inorganic filler is preferably 20 to 70% by weight based on the glass nonwoven fabric. If the proportion is less than 20% by weight, the measling resistance is not effective, and if it exceeds 70% by weight, the contact points between the glass fibers are decreased and the tensile strength of the glass nonwoven fabric is lowered, which is not preferable.

Examples of the glass nonwoven fabric used in the present invention include those made of non-alkali glass E glass fiber having excellent electrical characteristics. More preferably, the E glass fiber is surface-treated with a silane coupling agent.

Examples of the thermosetting resin used in the present invention include epoxy resins, polyimide resins, unsaturated polyester resins and modified resins thereof, and these may be used alone or in admixture of two or more.

The prepreg used in the present invention can be prepared by impregnating and drying a thermosetting resin in a non-woven fabric base material containing an inorganic filler by a conventional method, and an inner layer plate made of a prepreg and a copper foil can also be prepared by a conventional method. The copper foil used in the present invention may be either a rolled copper foil or an electrolytic copper foil, and those usually used for printed boards are also used.

Next, the layer structure of the multilayer copper clad laminate of the present invention will be described with reference to the drawings. One or a plurality of prepregs (A) 2 formed by impregnating a glass nonwoven fabric containing an inorganic filler with a thermosetting resin and drying the prepreg (A) 2 on the front and back sides of the inner layer board 1 having forming circuits on both sides Then, the prepreg (B) 3 formed by impregnating and drying a normal glass cloth (woven cloth) with a thermosetting resin is overlaid on the upper and lower surfaces thereof, and the outer copper foil 4 is overlaid on both surfaces thereof and heated. It is possible to form a multi-layer copper clad laminate by pressure molding. Although FIG. 1 shows a four-layer plate, the present invention is not limited to the four-layer plate, but may be applied to a plate having five or more layers. In short, multiple prepregs [(A) + on both sides of the circuit-formed inner layer board
(B)], the prepreg (A)
It is important to arrange the so as to contact the inner layer plate. 6
In the case of more than a layer board, the prepreg (B) may be arranged only on the outer layer copper foil side and the prepreg between the inner layer boards may be only the prepreg (A), or the number of prepregs (A) to be arranged is It may be one.

(Operation) In the present invention, since the glass nonwoven fabric containing the inorganic filler is impregnated with the thermosetting resin and dried, impregnation failure or coating unevenness in the glass woven fabric base material prepreg can be prevented. Further, since the prepreg made by impregnating and drying the thermosetting resin in the glass non-woven fabric containing the inorganic filler is arranged so as to be in contact with the circuit-formed inner layer plate, it is possible to improve the fluidity of the prepreg during processing. Moreover, it is possible to prevent the occurrence of voids.

(Examples) Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

Example 1 To 100 parts by weight of a brominated epoxy resin (epoxy equivalent: 470 g / eq, bromine content: 20.5%), 3 parts by weight of ginciadiamide, 0.2% by weight of benzyldimethylamine, and an appropriate amount of dimethylformamide or acetone were added and stirred. Then, an epoxy resin varnish was prepared. Next average length 13μ
m, glass fiber with an average diameter of 9 μm was mixed with 20% by weight of aluminum hydroxide powder with an average particle diameter of 2 μm as an inorganic filler, and a glass nonwoven fabric with a single weight of 60 g / m ² was impregnated with the epoxy resin varnish. Then, dry it at 160 ℃ and unit weight 300
A prepreg (A) of g / m ² was obtained. Then, the epoxy resin varnish was impregnated into a glass woven cloth having a thickness of 100 μm by a conventional method and dried to obtain a prepreg (B). Next, thickness 70μ on both sides
2 layers of prepreg (A) on the front and back of a 0.5 mm thick inner layer board having an inner copper foil circuit of m, and 1 layer of prepreg (B) on both sides, and an outer layer copper layer of 18 μm thickness The foils were laminated and integrally molded by heating and pressing at 175 ° C. for 90 minutes to produce a 4-layer copper clad laminate.

Example 2 A sheet made by mixing 30% by weight of E glass powder having an average particle size of 5 μm as an inorganic filler into glass fiber having an average length of 13 mm and an average diameter of 9 μm in place of the glass nonwoven fabric used in Example 1 A prepreg (C) was obtained in the same manner as in Example 1 except that a glass nonwoven fabric having a weight of 60 g / m ² was used, and a 4-layer copper-clad laminate was produced.

Comparative Example 1 A glass non-woven fabric of a conventional type having a single weight of 60 g / m ^{2 produced} by making glass fibers having an average length of 13 mm and an average diameter of 9 μm without an inorganic filler, and the epoxy resin varnish used in Example 1 as the above glass non-woven fabric. On the other hand, the average particle size is 2 μm, which is 10% by weight.
The varnish obtained by blending the aluminum hydroxide powder of 1. was impregnated, coated and dried to obtain a prepreg (D) having a unit weight of 300 g / m ^2.
I got A four-layer copper-clad laminate was produced with the same configuration as in Example 1 except that the prepreg (D) was used instead of the prepreg (A).

Comparative Example 2 A glass cloth having a thickness of 180 μm was impregnated with the epoxy resin varnish used in Example 1 and dried to prepare a prepreg (E).
I got A four-layer copper-clad laminate was manufactured with the same configuration as in Example 1 except that the prepreg (E) was used instead of the prepreg (A).

Regarding the four-layer copper-clad laminates produced in Examples 1-2 and Comparative Examples 1-2, the number of voids generated, measling resistance,
Tests were conducted for drill workability, and the results are shown in Table 1. The multilayer copper clad laminate of the present invention is superior to the conventional one, and the effect of the present invention was confirmed.

[Effects of the Invention] As is clear from the above description and Table 1, the multilayer copper-clad laminate of the present invention is an inner layer of a prepreg obtained by impregnating and drying a thermosetting resin in a glass nonwoven fabric containing an inorganic filler. By placing it in contact with the plate, it has good drilling workability, no inner wall roughness or smear, excellent measling resistance, good formability, and no voids.
An excellent multilayer copper clad laminate could be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the layer structure of a multilayer copper clad laminate according to the present invention. 1 ... Inner layer plate, 2 ... Prepreg (A) (glass non-woven fabric substrate with inorganic filler), 3 ... Prepreg (B), 4
…… Outer layer copper foil.

Claims (2)

(57) [Claims] 1. A multilayer copper clad laminate obtained by stacking a plurality of prepregs and an outer layer copper foil on the front and back of an inner layer board on which a circuit is formed, and integrally molding the layers by heating and pressing. As the prepreg in contact with the inner layer board, a multi-layer copper-clad laminate characterized by using a prepreg obtained by impregnating a non-woven fabric containing an inorganic filler with a thermosetting resin and drying the prepreg by blending at the time of papermaking . 2. The inorganic filler has an average particle size of 1 to 10 μm,
The multilayer copper clad laminate according to claim 1, which is contained in an amount of 20 to 70% by weight based on the glass nonwoven fabric.