JPH0563324A - Multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To make equal behaviors, such as deformations, under heating and pressing at the time of bonding in a multilayer structure and to lessen an irregularity in dimensional changes by a method wherein glass clothes having the same weave characteristics are used as base materials for an internal layer plate, an external layer plate and a prepreg for bonding use. CONSTITUTION:One of factors of large dimensional changes at the time of bonding in a multilayer structure is due to the weave characteristics of glass clothes to be used. The weave characteristics are a filament diameter, the weight per unit area of a filament, the thickness of the filament, the weave density of a strand, a tensile strength and the like and they respectively affect deformations at the time of bonding in the multilayer structure. When two kinds or more of the glass clothes are used in combination with one another, the deformations at the time of bonding in the multilayer structure are unevenly generated because the weave characteristics of the clothes are different from one another and an irregularity in the dimensional changes is increased. In the case the weave characteristics of the base materials are same, behaviors, such as the deformations, at the time of heating and pressing are also same and a shift is not generated in each of the base materials. As a result, an irregularity in the dimensional changes at the time of bonding in the multilayer structure is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board (hereinafter referred to as "multilayer board") having a small dimensional change and a high dimensional accuracy.

[0002]

2. Description of the Related Art A multi-layer board is a single-sided copper-clad laminate board with adhesive prepregs on both sides of an inner-layer board that has been processed in advance.
It is a double-sided copper-clad laminate having a circuit processed on one side on the inner layer side, or a component in which a copper foil is arranged in the outermost layer, which are laminated and integrated by heating and pressing. After lamination, drilling, through-hole plating, outer layer circuit processing, etc. are performed to make a printed wiring board.

The copper-clad laminate used as the inner layer plate or the outer layer plate is obtained by laminating a prepreg obtained by impregnating a glass cloth with a thermosetting resin, and a copper foil, and heating and pressing. Generally, the types of glass cloth used for copper clad laminates and prepregs are
Compliant with MIL standard, nominal thickness 50μm, 100μ
There are four types: m, 150 μm, and 200 μm. Its typical weaving properties are as follows. Nominal thickness 50 μm Filament diameter: 5 μm, weight: 48 g / m ² , thickness:
0.055 mm, warp density: 60/25 mm, weft density: 47/25 mm, vertical tensile strength: 21 kg / 2
5 mm, transverse tensile strength: 14 kg / 25 mm, nominal thickness 100 μm, filament diameter: 7 μm, weight: 104 g / m ² , thickness: 0.100 mm, warp weave density: 59/25 mm, weft weave density: 57/25 mm, warp Tensile strength: 40kg
/ 25 mm, transverse tensile strength: 33 kg / 25 mm Nominal thickness 150 μm Filament diameter: 6 μm, weight: 150 g / m ² , thickness: 0.135 mm, warp density: 64/25 mm, weft density: 46/25 mm, Vertical tensile strength: 64kg
/ 25 mm, transverse tensile strength: 42 kg / 25 mm Nominal thickness 200 μm Filament diameter: 9 μm, weight: 209 g / m ² , thickness: 0.180 mm, warp weaving density: 44/25 mm, weft weaving density: 33/25 mm, Longitudinal tensile strength: 70kg
/ 25mm, lateral tensile strength: 50kg / 25mm

The copper clad laminate and the adhesive prepreg are usually made of glass cloth having different weaving characteristics. For example, for the outer layer board, a thick glass cloth with a thickness of 150 μm or 200 μm is used to ensure the plate thickness accuracy and the material cost is low, and a low resin content (40 to 45%) is used. A thin glass cloth with a thickness of 50 μm and 100 μm is used to have a high resin content (50 to 60%) in order to prevent voids from being generated and to improve moldability.

[0005]

The dimensional change in the manufacturing process of a multilayer board is large. The inner layer plate slightly expands due to polishing in the circuit processing step and then largely contracts in the multi-layer adhesion step. Further, although the outer layer circuit is slightly shrunk in the circuit processing and finishing steps, the dimensional change of the inner layer plate and its variation are the largest before and after the multi-layer adhesion.

With the miniaturization and multi-functionalization of so-called electronic equipment such as OA equipment and communication equipment, the multi-layer board has a higher number of layers,
With higher density, through-hole reliability, heat resistance, and dimensional stability are becoming increasingly necessary. Among the multi-layer boards, especially for six-layer boards or more, it is necessary to minimize the positional deviation between the layers, and a material with high dimensional accuracy is required. The present invention is
An object is to provide a multi-layer board having good dimensional accuracy.

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, a glass cloth used as a base material for an inner layer board and an adhesive prepreg is a glass cloth having the same weaving characteristics, and a multilayer printed wiring board. Is. When the outer layer board is used instead of the outer layer copper foil, the base material of the outer layer board is a glass base material having the same weaving characteristics as those of the inner layer board and the adhesive prepreg.

[0008]

[Function] One of the factors that causes a large dimensional change during multi-layer adhesion is shrinkage caused by residual stress of the inner layer plate being released by heating and shrinkage caused by the flow of resin impregnated in the prepreg and curing reaction. It is the deformation caused by the stress of. Yet another factor is due to the weaving properties of the glass cloth used. The weaving characteristics include filament diameter, weight per unit area, thickness, weaving density of strands, tensile strength, etc., each of which has an effect on deformation during multilayer adhesion. When two or more kinds of glass cloths are used in combination, the weaving characteristics are different, so that the deformation during multi-layer adhesion occurs unevenly and the variation in dimensional change becomes large. According to the present invention, the weaving characteristics of the base material are the same, so the behaviors such as deformation during heating and pressing are also the same and do not deviate from each other. Therefore, variations in dimensional change during multi-layered bonding are reduced.

[0009]

Example 1 Three prepregs obtained by impregnating and drying a resin having a resin content of 42 to 44% in a glass cloth having a thickness of 100 μm and a thickness of 3
A double-sided plate having a thickness of 0.3 mm was obtained by using two 5 μm copper foils. A circuit pattern was formed on this inner layer plate using a model pattern having a residual copper rate of about 30%. Further, a glass plate having a thickness of 100 μm was impregnated with a resin so as to have a resin content of 51 to 53% and dried, and a copper foil having a thickness of 18 μm was used to obtain a single-sided plate having a thickness of 0.1 mm. Furthermore, thickness 100
A resin cloth was impregnated into a glass cloth of μm so as to have a resin content of 42 to 44% and dried to obtain an adhesive prepreg. The inner layer plate 2
Three prepregs for adhesion were sandwiched between the sheets, and a single-sided plate was arranged on the outside of the inner layer plate with two prepregs for adhesion so that the copper foil surface was on the outside. The four sets of 6-layer plate components thus obtained were sandwiched between the components by a stainless steel plate having a thickness of 1.0 mm, and were inserted between two jig plates having a thickness of 5.0 mm. Insert a cushion between the hot plate and 175
The mixture was heated and pressurized at 3 ° C. for 80 minutes. After heating, it was cooled for 30 minutes in a pressurized state. The product size is 500 ×
It is 500 mm.

The dimensional change of the 6-layer plate molded according to Example 1 was measured by the following method. 250-45 of the second layer circuit surface
Measure the distance between 0 mm pitches with a vertical and horizontal coordinate projector at 10 locations,
A tetrafluoroethylene tape was attached to the measurement land portion, and after multi-layer adhesion, the portion was spotted and measured again. The results are shown in Fig. 1 (a). The calculation formula of the dimensional change rate is as follows. [(Dimension before multilayer adhesion-Dimension after multilayer adhesion) / Dimension before multilayer adhesion] × 100

Example 2 Two pieces of prepreg obtained by impregnating and drying a resin having a resin content of 40 to 42% on a glass cloth having a thickness of 150 μm, and a thickness of 3
A double-sided plate having a thickness of 0.3 mm was obtained by using two 5 μm copper foils. In addition, the resin content 48 ~
A resin was impregnated and dried to 50% to obtain an adhesive prepreg. Two adhesive prepregs were sandwiched between the two inner layer boards, and a copper foil having a thickness of 18 μm was arranged on the outside of the inner layer board with the two adhesive prepregs interposed. Thereafter, a 6-layer plate was obtained in the same manner as in Example 1, and the dimensional change rate was measured. The result is shown in FIG.

Comparative Example 1 Using the double-sided plate obtained in Example 2 instead of the double-sided plate of Example 1, a 6-layer plate was obtained in the same manner as in Example 1 and the dimensional change rate was measured. The result is shown in FIG. Comparative Example 2 Instead of the bonding prepreg of Example 2, the bonding prepreg obtained in Example 1 was used, three bonding prepregs were arranged between the layers, and a 6-layer board was prepared in the same manner as in Example 2 below. Got
The dimensional change rate was measured. The result is shown in FIG.

[0013]

According to the present invention, a glass cloth having the same weaving property is used as a base material for the inner layer plate, the outer layer plate and the bonding prepreg. They are the same and do not shift from each other. Therefore, variations in dimensional change during multi-layered bonding are reduced.

[Brief description of drawings]

FIG. 1 is a graph showing dimensional changes of examples of the present invention and comparative examples.

Claims (2)

[Claims] 1. A multilayer printed wiring board characterized in that the glass cloth used as a base material for the inner layer board and the prepreg for bonding is a glass cloth having the same weaving characteristics. 2. A multilayer printed wiring board, wherein the glass cloth used as the base material for the inner layer board, the outer layer board and the adhesive prepreg is a glass cloth having the same weaving characteristics.