JP2000196238A - Manufacture of multilayer metal foil laminate board with inner circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect the surface of a multilayer metal foil laminate board inner layer circuit from the generation of a roughness, even when a metal mirror surface plate whose thickness is 0.8 mm or less is used for intervention between each combination of boards, when performing thermal bonding of a plural of combinations of boards between press heating one step platens. SOLUTION: A prepreg and a metal foil are arranged in this order on the both ends of a core substrate from inner to outer to form a laminated structure 1. A plurality of laminated structures are loaded between press heating platens via a metal mirror surface plate 2 whose thickness is 0.8 mm or less. A metal mirror surface plate 3 whose thickness is 1 mm or more is arranged on the upper and lower of the laminated structure comprising a plurality of laminated combinations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer metal foil-clad laminate having an inner layer circuit used for manufacturing a multilayer printed wiring board.

[0002]

2. Description of the Related Art Multilayer metal foil-clad laminates containing an inner circuit are:
Manufactured by stacking multiple sets of laminated structures in which a prepreg layer and metal foil are stacked in this order from the inside to the outside on both sides of the circuit-formed core substrate, put it in one press hot platen, and heat and press mold Is done. When there are a plurality of core substrates constituting one laminated structure, a prepreg layer is also interposed between the core substrates. The resin in the prepreg is melted at the time of the heat and pressure molding, and functions as an adhesive layer for integrating the laminated structure. Further, the molten resin flows into the recess between the printed wirings of the core substrate and fills the recess. In order to separate each laminated structure, a metal mirror plate is interposed between the laminated structures. Heat and pressure molding is performed between the upper and lower metal mirror plates and the press hot plate of the laminated structure in which a plurality of sets are stacked with a cushion material interposed therebetween.

When a large number of products are to be manufactured by one heat and pressure molding, the production size of a multilayer metal foil-clad laminate is increased, or the number of sets of laminated components to be put in one stage of a hot platen is reduced. More is conceivable. If the manufacturing size is increased when there are a plurality of core substrates constituting one laminated structure, the accuracy of positioning the printed wiring between layers deteriorates, so that the manufacturing size cannot be increased.
In particular, as the number of printed wiring layers increases, the upper limit of the manufacturing size is limited to a smaller value. When trying to increase the number of sets of laminated components to be put into one press hot platen, the thickness of the metal mirror plate to be arranged to separate the laminated components should be thin because the interval of one press hot platen is constant. Otherwise, the number of input sets of the laminated structure cannot be increased.

The thickness of a metal mirror plate is generally 1 to 1.2 mm, but there is an attempt to use a metal mirror plate having a thickness of 0.8 mm or less in order to increase the number of sets. However, when the metal mirror plate is made thin, there is a concern that the surface properties of the cushion material may be transferred to the surface of the multilayer metal foil-clad laminate formed at the position closest to the cushion material through the metal mirror plate. Furthermore, when the number of sets of laminated components to be put into one press heating plate increases, the metal mirror plate is deformed due to the unevenness of the printed wiring of the core substrate at the time of heating and pressing, and as a result,
There is also a concern that the irregularities may be transferred to the surface of the adjacent multilayer metal foil-clad laminate via the metal mirror plate. If the above-mentioned transfer is present on the surface of the multilayer metal foil-clad laminate, poor adhesion of a photosensitive resin film to be laminated for forming printed wiring on the surface in a later step, mounting failure of components, and the like will result. As a means for avoiding the above-mentioned transfer, it is conceivable to set the pressure at the time of heating and pressing the laminated structure to a low pressure.
However, due to insufficient pressure, there is concern that the resin interposed between the printed wiring of the core substrate and the resin melted during the heat and pressure molding may not be sufficiently filled, and the prepreg characteristics may be changed to improve the fluidity when the resin in the prepreg is melted. It needs to be better. On the other hand, such a change in prepreg characteristics leads to a decrease in product performance such as metal foil peeling strength, heat resistance, and thickness accuracy. In order to increase the productivity, it was difficult to change the thickness of the metal mirror plate to be thin, and to maintain the same product performance as before the change.

[0005]

The problem to be solved by the present invention is that even when a metal mirror plate having a thickness of 0.8 mm or less is used, a cushion material or a core material can be used without changing the prepreg characteristics. An object of the present invention is to manufacture a multilayer metal foil-clad laminate having an inner layer circuit in which unevenness due to printed wiring of a substrate is not transferred to the surface.

[0006]

A plurality of sets of a laminated structure in which a prepreg layer and a metal foil are stacked in this order from the inside to the outside on both sides of a core substrate on which a circuit is formed are stacked and put into one stage of a press hot platen. During the heat and pressure molding, a metal mirror plate having a thickness of 0.8 mm or less is interposed between the laminated structures.
In such a case, a metal mirror plate having a thickness of 1 mm or more is arranged on the upper and lower sides of the laminated structure in which the plurality of sets are stacked. By arranging a metal mirror plate having a thickness of 1 mm or more, it is possible to prevent the surface properties of the cushion material from being transmitted to the surface of the multilayer metal foil-clad laminate containing the inner layer circuit during molding.

[0007] When the number of sets of the laminated structure to be put into one stage of the press heating plate increases, the unevenness of the printed wiring of the core substrate is accumulated, and the unevenness is easily transferred to the surface of the multi-layer metal foil-clad laminate having the inner layer circuit. Become. Therefore, in addition to the upper and lower sides of the stacked structure stacked in one stage of the press hot platen, a metal mirror plate having a thickness of 1 mm or more is additionally arranged between a predetermined number of stacked stacked structures. Also, it is possible to avoid unevenness on the surface of the multilayer metal foil-clad laminate containing the inner layer circuit, which is caused by unevenness of the printed wiring of the core substrate.

[0008]

The method according to the invention does not require any change in the properties of the prepreg. Just by partially adding a metal mirror plate with a thickness of 1 mm or more as described above,
It is possible to manufacture a multilayer metal-clad laminate having an inner layer circuit with no unevenness on the surface without deteriorating the product performance such as metal foil peeling strength, heat resistance and thickness. The metal mirror plate having a thickness of 0.8 mm or less is made of a material such as stainless steel, iron, and aluminum, and is not particularly limited. Even a metal mirror plate made of a material having a low hardness such as aluminum can be used without any trouble. The method according to the present invention is particularly effective when a metal mirror plate made of a material having a low hardness is used.

The charging of the laminated structure between press hot plates is performed, for example, as shown in FIG. That is, the laminated structure 1 is sandwiched between metal mirror plates 2 having a thickness of 0.8 mm or less, and a plurality of sets are put into one stage of a hot platen (not shown). The laminated structure 1 and the metal mirror plate 2 having a thickness of 0.8 mm or less are alternately stacked. On the upper and lower sides of the stacked structure, a metal mirror plate 3 and a cushion material 4 having a thickness of 1 mm or more are arranged in this order from inside to outside.

[0010]

Example 1 A 0.1 mm thick glass fiber woven base epoxy resin prepreg (equivalent to ANSI grade FR-4) was prepared as a prepreg. Further, as a core substrate, a glass fiber woven base epoxy resin double-sided copper-clad laminate (1.2 mm thick corresponding to ANSI grade FR-4, copper foil thickness 35 μm) was prepared by printed wiring processing. A copper foil having a thickness of 18 μm is arranged on both sides of the core substrate via the prepreg to form a laminated structure 1, which is inserted between press hot plates as described in FIG. Then, a four-layer copper-clad laminate having an inner circuit having a thickness of 1.6 mm was obtained. The number of sets of the laminated structure 1 to be put in between one stage of the press hot platen was in the range of 10 to 20. 0.8mm thick metal mirror plate 2
Is 0.8 mm thick made of aluminum, and the metal mirror plate 3 is 1 mm thick or more and 1.2 mm thick made of stainless steel. The cushion material 4 is formed by stacking ten kraft papers each having a thickness of 0.2 mm.

Example 2 In Example 1, the metal mirror plate 2 having a thickness of 0.8 mm or less was made 0.4 mm thick made of aluminum, and the metal mirror plate 3 having a thickness of 1 mm or more was made 1.0 mm thick made of stainless steel. Further, the number of sets of the laminated structure 1 to be put in between the press hot plates was set in a range of 10 to 12. The rest is the same as the first embodiment.

Example 3 A double-sided copper-clad laminate made of glass fiber woven base epoxy resin (0.4 equivalent to ANSI grade FR-4) was used as a core substrate.
mm thickness, copper foil thickness 35 μm) were prepared by printed wiring processing. A copper foil having a thickness of 18 μm is arranged on both sides of the core substrate via the prepreg of Example 1 to form a laminated structure 1, which is stacked in a range of 20 to 30 sets as shown in FIG. 2. That is, in addition to the upper and lower sides of the stacked structure 1 stacked between the press hot plates, the metal mirror plate 3 having a thickness of 1 mm or more is additionally arranged at a position where the stacked structure is bisected. In the same manner as in Example 1, heat and pressure molding was performed to integrate the resultant into a 0.8-mm thick 4-layer copper-clad laminate with an inner circuit. The metal mirror plate 2 having a thickness of 0.8 mm or less was made 0.4 mm thick made of aluminum, and the metal mirror plate 3 having a thickness of 1 mm or more was made 1.2 mm thick stainless steel.

Example 4 A double-sided copper-clad laminate of glass fiber woven base epoxy resin (ANSI grade FR-4 equivalent 0.0
6 mm thick, 18 μm thick copper foil) were prepared by printed wiring. A copper foil having a thickness of 18 μm is arranged on both sides of the core substrate via the prepreg of Example 1 to form a laminated structure, which is stacked in a range of 30 to 40 sets. In addition to the upper and lower sides of the stacked structure stacked between the press hot plates, a metal mirror plate 3 having a thickness of 1 mm or more is additionally arranged at a position where the stacked structure is divided into three. In the same manner as in Example 1, heat and pressure molding was performed and integrated to obtain a 0.3-mm thick 4-layer copper-clad laminate with an inner circuit. The metal mirror plate 2 having a thickness of 0.8 mm or less was made 0.4 mm thick made of aluminum, and the metal mirror plate 3 having a thickness of 1 mm or more was made 1.2 mm thick stainless steel.

Comparative Example In the first embodiment, the metal mirror plate 3 having a thickness of 1 mm or more was omitted from the upper and lower sides of the laminated structure stacked between the press hot plates.

Conventional Example In the first embodiment, the metal mirror plate 2 having a thickness of 0.8 mm or less is 1 mm.
The metal mirror plate 3 (thickness: 1.2 mm, stainless steel) was replaced with a metal plate having a thickness of not less than 10 mm. It should be noted that there is one metal mirror plate 3 having a thickness of 1 mm or more disposed on the upper side and the lower side of the laminated structure stacked between the press hot plates.

Table 1 shows the results of visually confirming the presence or absence of surface irregularities of the four-layer copper-clad laminate containing the inner layer circuit manufactured in each of the above examples. In the comparative example, fine irregularities transferred from the cushion material were present on the side surface of the press hot plate of the four-layer copper-clad laminate with the inner layer circuit formed at the position closest to the press hot plate.

[0017]

[Table 1]

[0018]

As is clear from Table 1, according to the method according to the present invention, the cushioning material and the core substrate can be used without changing the prepreg characteristics, using a thin metal mirror plate having a thickness of 0.8 mm or less. It is possible to manufacture a multi-layer metal foil-clad laminate having an inner layer circuit without transfer of unevenness due to the printed wiring.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of the invention according to the present invention in which a laminated structure is heated and pressed between press hot plates.

FIG. 2 is an explanatory view showing another embodiment of the present invention in which a laminated structure is heated and pressed between press hot plates.

[Explanation of symbols]

 1 is a laminated structure 2 is a metal mirror plate of 0.8 mm or less in thickness 3 is a metal mirror plate of 1 mm or more in thickness 4 is a cushion

Claims (2)

[Claims] 1. A plurality of sets of a laminated structure in which a prepreg and a metal foil are laminated in this order from the inside to the outside on both sides of a core substrate on which a circuit is formed, are stacked and put into a press hot platen, and each laminated structure is placed. When integrating by heat and pressure molding, a metal mirror plate having a thickness of 0.8 mm or less is interposed between the respective laminated components, and the upper and lower sides of the laminated components stacked in one stage of the press hot platen are provided. A method for producing a multilayer metal-clad laminate having an inner circuit, wherein a metal mirror plate having a thickness of 1 mm or more is arranged. 2. In addition to the upper and lower sides of the stacked structure, a thickness of 1 mm is set between a predetermined number of sets of the stacked structure.
The method for producing a multilayer metal-clad laminate with an inner layer circuit according to claim 1, wherein the metal mirror plate is additionally arranged.