JPH05129779A - Metal-clad laminate for multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To enable a laminated board small in thickness to be lessened in dimensional change and warpage in and after a process where the laminate boards are formed into a multilayered board by a method wherein fiber base material is impregnated with resin, dried up, and controlled in resin component to form a prepreg, and an inner circuit is formed of only a single sheet, of prepreg. CONSTITUTION:A circuit is formed on a single side or both the sides of an insulating layer composed of a fiber base material and matrix resin to form an inner circuit board, and an outer copper foil is bonded to the inner circuit board into one piece through the intermediary of an adhesive insulating layer composed of fiber base material and matrix resin for the formation of a metal foil plated laminated board. For instance, glass cloth 0.2mm in thickness is used as fiber base material, epoxy resin is employed as matrix resin, and an adhesive insulating layer is formed of prepreg composed of two sheets of glass fiber base material 0.1mm in thickness and epoxy resin or a sheet of glass fiber base material 0.15mm in thickness and epoxy resin. The insulating layer of an inner circuit board is formed of glass cloth base material prepreg 37-43% in resin component and 0.2mm in thickness. By this setup, laminated boards can be lessened in dimensional change in a process where they are formed into a multilayered laminated board.

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 laminate for a multilayer printed wiring board, and more particularly to a metal foil-clad laminate for a multilayer printed wiring board in which the inner layer circuit board has a small thickness.

[0002]

2. Description of the Related Art A metal foil-clad laminate for a multilayer printed wiring board (hereinafter simply referred to as a multilayer board) is a laminate for an inner layer circuit board and an outer layer circuit or a metal foil for an outer layer circuit (a copper foil is used as the metal foil). Since most of them are represented by copper foil below), these are bonded and integrated by a bonding prepreg for securing insulation between layers. Normal,
The inner layer circuit board is formed by stacking a plurality of prepregs, heating and pressurizing them to form a laminated board having a predetermined thickness.

When a thin multilayer board is manufactured, inner layer circuits are formed on both sides of a double-sided copper-clad laminate in which a copper foil having a thickness of 35 μm is laminated and formed on both sides of an insulating layer having a thickness of 0.2 mm in advance.
A prepreg of 0.1 mm or 0.15 mm is placed on the inner layer circuit surface and heated and pressed to laminate and manufacture a thin 4-layer printed wiring board. Normally 0.2mm of inner layer circuit board
The insulating layer uses two 0.1 mm prepregs.

For example, in the case of a four-layer board, glass cloth is used as a base material, and prepregs obtained by impregnating and drying a thermosetting resin such as epoxy resin or polyimide resin are arranged above and below the inner layer circuit board, and outside thereof. The metal foil is placed on the substrate, sandwiched between jigs such as a stainless plate, and heated and pressed to manufacture.

[0005]

In recent years, the wiring of a multilayer board has been densified, signal lines have been inserted in the inner layer circuit, and the diameter of the through hole has been reduced. As a result, the connection land for the inner-layer signal line was also made smaller, and it was necessary to have better dimensional accuracy.

On the other hand, in order to mass-produce inexpensively in a large amount, a mass lamination method capable of multi-faced attachment to a large substrate is adopted. . Unlike the small size pin lamination method, the mass lamination method is large in size and does not use a fixed pin, so that it is more difficult to control the dimensional accuracy.

Recently, a multilayer board is a VTR with a built-in camera.
It has come to be used in large quantities in consumer equipment such as, and the thinning has been rapidly progressing with it. However, a thin multilayer board undergoes large dimensional changes and warpage both when it is laminated and processed and when it is processed into a printed wiring board. It is an object of the present invention to provide a multi-layer board having small dimensional changes and warpage and a small thickness.

[0008]

The present invention comprises an inner layer circuit board having a circuit formed on both sides or one side of an insulating layer consisting of one fiber base material and a matrix resin, and a fiber base material and a matrix resin. It is characterized in that it comprises an outer layer copper foil bonded and integrated with the inner layer circuit board via an adhesive insulating layer.

For example, as a fiber base material, a thickness of 0.2 mm
Glass cloth, epoxy resin as a matrix resin, and for adhesion, a prepreg consisting of two glass fiber base materials having a thickness of 0.1 mm and an epoxy resin or one glass fiber base material having a thickness of 0.15 mm and an epoxy resin. To use.

The resin content is 37 to 43% and the thickness is 0.2 m.
The insulating layer of the inner layer circuit board is formed by the glass cloth base material prepreg of m. 0.2m to form a 0.2mm insulating layer
It is technically difficult to mold a single m-prepreg. In order to make the dimensional change smaller, it is advantageous to make the resin content of the 0.2 mm prepreg smaller.
Voids are easily generated during lamination and molding. 0.
When the resin content of 2 mm is 36%, voids are observed, which is not preferable. A high resin content is advantageous during lamination and molding, but a too high resin content adversely affects dimensional change and warpage. The resin content of 0.2 mm is most preferably 37% to 43%.

[0011]

[Operation] Insulation layer thickness of inner layer circuit board copper clad laminate 0.2m
Normally, two 0.1 mm prepregs are used to form m, but by forming one 0.2 mm prepreg, dimensional changes during multilayer molding of a multilayer printed wiring board using the prepreg can be significantly reduced. Can be reduced. Further, with the structure of the present invention, it is possible to reduce the warp of the multilayer printed wiring board after the lamination molding. Although this effect is not known in detail, if there are a plurality of fiber base materials, the residual stress caused by the resin flow during molding becomes uneven due to the base materials. It is considered that this is because the tensile strength does not work uniformly on the two sheets and changes in a non-uniform state in terms of dimensions.

[0012]

EXAMPLE A flame-retardant epoxy resin varnish (corresponding to FR-4 of NEMA standard) is impregnated and adhered to a glass cloth having a thickness of 0.1 mm, a glass cloth having a thickness of 0.15 mm and a glass cloth having a thickness of 0.2 mm to form a resin. Minutes were adjusted and dried to obtain a prepreg.

Next, two prepregs made of glass cloth having a thickness of 0.1 mm are stacked, 35 μm copper foil is arranged on both sides of the prepreg, and one prepreg made of a glass cloth having a thickness of 0.2 mm is used on both sides of the prepreg. A copper foil having a thickness of 35 μm was heated and pressed to form two types of copper-clad laminates having an insulating layer thickness of 0.2 mm. Then, an inner layer circuit board was formed in which inner layer circuits were formed on both surfaces of each copper-clad laminate.

The prepreg and the inner layer circuit board were combined and laminated and molded under a pressure of 3.0 MPa and a reduced pressure of 1333 Pa or less to obtain a multilayer board.

Then, the dimensional change and warpage before and after the lamination molding were measured. The measurement results are shown in Tables 1 and 2 together with the combination of the inner layer circuit board and the prepreg.

As for the warp, after laminating and molding, the outermost copper foil is removed by etching, dried at 120 ° C. for 1 hour, and then allowed to stand on a surface plate, and the maximum gap with the surface plate is measured. It is the value expressed in% divided by the long side of the board.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

According to the present invention, by forming the insulating layer of the inner layer circuit board with one prepreg, it is possible to reduce the dimensional change and warp after the lamination molding. that's all,
Although the case where the number of the inner layer circuit boards is one has been described, it goes without saying that the present invention is effective even when the number of the inner layer circuit boards is two or more.

Claims (3)

[Claims] 1. An inner layer circuit board in which a circuit is formed on both sides or one side of an insulating layer composed of one fiber base material and a matrix resin, and the inner layer via an adhesive insulating layer composed of the fiber base material and the matrix resin. A metal foil-clad laminate for a multilayer printed wiring board, comprising an outer layer circuit laminate or a metal foil for an outer layer circuit integrally bonded to a circuit board. 2. The fiber base material is a glass cloth having a thickness of 0.2 mm, the matrix resin is an epoxy resin, and the adhesive insulating layer has two glass fiber base materials having a thickness of 0.1 mm and an epoxy resin or 0.15 mm. The metal foil-clad laminate for a multilayer printed wiring board according to claim 1, comprising one glass fiber base material and an epoxy resin. 3. The metal for a multilayer printed wiring board according to claim 1, wherein the insulating layer of the inner layer circuit board is formed by a glass cloth base material prepreg having a resin content of 37 to 43% and a thickness of 0.2 mm. Foil-clad laminate.