JPH07226593A - Multilayer wiring board and its manufacture - Google Patents

Abstract

PURPOSE:To realize molding property improvement, surface flatness and thinness of a multilayer wiring board and to improve reliability of interlaminar connection and heat dissipation of a substrate by arranging a filler in a recessed part between circuits of a multilayer wiring board wherein an insulation bonding material and a circuit layer are laminated at least once on a circuit board. CONSTITUTION:After a recessed part filler 3 is printed or applied to a necessary part of a circuit board 1 or all over there by using a screen print method, etc., it is dried and set. In a process for laminating a copper foil 2 with an insulation bonding material which is bored in advance, polishing is carried out form removing the recessed part filler 3 on a conductor circuit of the circuit board 1 wherein the recessed part filler 3 is printed or applied in advance. After they are laminated and integrated, interlaminar connection can be carried out by conductive paste, etc., if necessary. Thereafter, an insulation bonding material 2b is bored by chemical etching by using sulfonic acid. A conductor circuit is formed by forming etching resist and removing unnecessary copper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board and its manufacturing method.

[0002]

2. Description of the Related Art In recent years, multi-layer wiring boards have been made higher in density and thinner, and a method of laminating a thin glass-epoxy prepreg between circuit boards to form a multi-layer structure or using no glass cloth is possible. A multilayer wiring board manufacturing method has been studied in which a sheet-like adhesive material having a property is sandwiched between circuit boards to form a multilayer structure. Further, a method of forming a so-called interstitial via hole in which only adjacent wiring layers are connected has been studied. As such an example, as disclosed in Japanese Patent Laid-Open No. 5-259649, there is a method of laminating a copper foil with an insulating adhesive material in which a hole for interlayer connection is preliminarily formed on a circuit board.

[0003]

Among the above-mentioned prior arts, the method of laminating and laminating using thin glass-epoxy prepreg has insufficient moldability and circuit filling because the resin flow amount is not sufficient. There is a problem that is not. Further, also in the method of sandwiching a flexible sheet-shaped adhesive material between circuit boards to form a multilayer, there is a problem that the circuit filling property is not sufficient when the thickness of the circuit copper foil is 35 μm or more. Furthermore, in a method of laminating a copper foil with an insulating adhesive material, in which holes for interlayer connection are preliminarily drilled, on a circuit board, especially when the thickness of the circuit is 35 μm or more, improvement of circuit filling property and interlayer connection There is a problem that it is difficult to reduce the flow rate of the insulating adhesive material through the holes.

[0004]

The multilayer wiring board of the present invention comprises:
A multilayer wiring board in which an insulating adhesive material and a circuit layer are laminated at least once on a circuit board is characterized by having a filling material in the concave portion between the circuits.

Such a multilayer wiring board can be manufactured by the following steps. (A) A step of forming a resin layer that can be Kamikel-etched on the entire surface of the circuit board. (B) A copper foil with an insulating adhesive layer, in which holes are preliminarily formed at necessary locations, is used as the insulating adhesive layer. Step of stacking and stacking so as to be in contact with the resin so as to be laminated and integrated (c) Step of removing the resin exposed from the hole by chemical etching (d) Connection between the outer layer copper foil and the circuit exposed from the hole, and Step of processing outer layer copper foil to form surface circuit (e) Step of repeating steps (a) to (d) according to the required number of circuit layers

The circuit board used in the present invention may be a glass cloth-copper-clad laminate using epoxy resin, a paper-copper-clad laminate using phenol resin, a metal base substrate, a metal core substrate, or the like. .

The composition of the recess filling material is not particularly limited as long as the insulation reliability is good, but for example, an epoxy resin type or a phenol resin type can be used. Also, a mixture of these resin systems and an inorganic filler can be used. Examples of such inorganic fillers include silica and alumina. In addition, commercially available thermosetting solder resist CCR-506GTH (manufactured by Asahi Kaken Co., Ltd.), UV curable solder resist PSR-4000 (manufactured by Asahi Kaken Co., Ltd.), etc. are used as the focus agents. May be.

As the insulating adhesive, a glass-epoxy prepreg or a film-like adhesive material containing a flexibility imparting component can be used. As the material imparting flexibility, a high molecular weight epoxy resin such as phenoxy or acrylic is used. Rubber materials such as rubber and acrylonitrile rubber, and JP-A-4-1-1
201222, JP 4-120123 A, JP 4-120124 A, JP 4-120125 A.
The high molecular weight epoxy resin or the ultrahigh molecular weight epoxy resin disclosed in Japanese Patent Laid-Open No. 4-122713, or Japanese Patent Laid-Open No. 4-122714 can be used.

The insulating adhesive is not particularly limited, but an epoxy resin-based insulating adhesive material or a copper foil coated with these can be used, and a film of these insulating adhesive materials and a copper foil can be used. It is also possible to use a laminated and integrated product.

By incorporating a highly heat-dissipating inorganic filler such as alumina, aluminum nitride, or boron nitride in the recess filling material and / or the insulating adhesive material, the heat dissipation of the multilayer wiring board can be improved and the heat dissipation is high. Combining with a circuit board is preferable for improving heat dissipation.

In the manufacturing method of the present invention, the method for printing or coating the recess filling material includes a screen printing method, a curtain coating method, a coating method using a squeegee, and the like. After printing or coating on a required portion or the entire surface, drying and curing are performed. The amount of the recess filling material needs to be printed or applied in an amount sufficient to fill the recess.

In the step of laminating the copper foil with the insulating adhesive material which has been preliminarily perforated, the circuit board on which the recess filler is printed or applied is polished to remove the recess filler on the conductor circuit. After stacking and integrating, interlayer connection can be performed by a conductive paste, plating, wire bonding or the like, if necessary.

A method of forming holes in the insulating adhesive material by chemical etching after laminating this insulating adhesive can be carried out by using sulfonic acids as an etching solution.

As a lamination method, a press, a vacuum press, a hot roll laminator, a vacuum laminator or the like can be used.

To form a circuit, an etching resist is formed, unnecessary copper is removed by etching, and a conductor circuit is formed at a necessary portion of the substrate.

[0016]

The multilayer wiring board is formed by flattening the recesses between the circuits with the filler and then laminating the adhesive material to improve the formability, surface flattening and thinning of the multilayer wiring board. be able to.

In the multi-layer wiring board, the recesses between the circuits are flattened with a resin, and then a copper foil with an insulating adhesive material or a bonding material, which has been subjected to perforation processing, is laminated in advance at a portion where the interlayer connection is made. The reliability of interlayer connection can be improved.

For the recess filling material and / or the insulating adhesive material,
The inclusion of the high thermal conductive inorganic filler can improve the heat dissipation of the substrate.

[0019]

【Example】

Example 1 (1) Solder resist CCR-506GTH (manufactured by Asahi Kaken Co., Ltd., on a wiring board having a copper foil thickness of 35 μm)
(Trade name) is printed so that the film thickness after drying and curing is 35 μm, and then dried and cured at 160 ° C. for 10 minutes. (2) Sheet-shaped insulating adhesive material (thickness 100 μm) whose main component is low-molecular epoxy resin
Is sandwiched between two wiring boards printed with the above-mentioned recess filling material, and integrated under heating and pressure. (3) By drilling and through-hole plating,
Perform interlayer connection.

Example 2 (1) Solder resist CCR-506GTH (manufactured by Asahi Kaken Co., Ltd., on a wiring board having a copper foil thickness of 70 μm,
(Trade name) is printed so that the film thickness after drying and curing is 70 μm, and then dried and cured at 160 ° C. for 10 minutes. (2) The solder resist on the circuit copper foil is removed by polishing. (3) A low-molecular epoxy resin is punched at a portion of the copper foil with an insulating adhesive material (thickness 50 μm) containing a high-molecular-weight epoxy resin as a main component to perform interlayer connection by punching,
This and the wiring board printed with the recess filling material are integrated under heating and pressure. (4) The layers are connected by plating. (5) Unnecessary copper foil is removed by etching to form a circuit pattern.

Example 3 The same procedure as in Example 2 is carried out except that the solder resist is applied by the screen printing method.

Example 4 (1) Solder resist CCR-506GTH (trade name, manufactured by Asahi Kaken Co., Ltd.) was dried and cured to a thickness of 70 μm on an aluminum base wiring board having a copper foil thickness of 70 μm.
After that, it is dried and cured at 160 ° C. for 10 minutes. (2) The solder resist on the circuit copper foil is removed by polishing. (3) A low-molecular epoxy resin is punched at a place where interlayer connection is made in a copper foil with an insulating adhesive material (thickness 50 μm) containing alumina filler as a main component, and this and the above-mentioned recess filling material. The wiring board printed with is heated and pressed to be laminated and integrated. (4) The layers are connected by plating. (5) Unnecessary copper foil is removed by etching to form a circuit pattern.

Comparative Example 1 The same procedure as in Example 1 was performed except that the recesses between the circuits were not filled with the recess filling material.

Comparative Example 2 The same procedure as in Example 2 was carried out except that the recesses between the circuits were not filled with the recess filling material.

The multilayer wiring board produced as described above was evaluated, and its characteristics are shown in Table 1.

The evaluation method is shown below. (Circuit filling property) Microscopic observation was conducted, and those having no voids having a diameter of more than 10 μm between the lower copper foil and the insulating adhesive material were considered good, and those having voids having a diameter of 10 μm or more were defective. And (Withstand voltage) At 25 ℃, AC voltage between the upper and lower circuits starts from 0V, rises at a speed of 100V / sec, current 1m
A: The voltage was defined as the dielectric breakdown when flowing. (Soldering heat resistance) The substrate is placed in a solder bath at 260 ° C for 180
It was soaked for a second, and those without swelling or peeling were regarded as good.

[0027]

[Table 1] 1) Withstand voltage is measured between upper and lower patterns.

From these results, the multilayer wiring board according to the present invention is superior in surface flatness to the comparative example.

[0029]

As described above, according to the present invention,
It is possible to improve the formability of the multilayer wiring board, make the surface flat and thin, improve the reliability of interlayer connection, and further improve the heat dissipation of the substrate.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

Claims (3)

[Claims] 1. A multilayer wiring board in which an insulating adhesive layer and a circuit layer are laminated at least once on a circuit board, wherein a filling material is provided in the recesses between the circuits. 2. A method for manufacturing a multilayer wiring board, comprising the following steps. (A) A step of forming a resin layer that can be Kamikel-etched on the entire surface of the circuit board. (B) A copper foil with an insulating adhesive layer, in which holes are preliminarily formed at necessary locations, is used as the insulating adhesive layer. Step of stacking and stacking so as to be in contact with the resin so as to be laminated and integrated (c) Step of removing the resin exposed from the hole by chemical etching (d) Connection between the outer layer copper foil and the circuit exposed from the hole, and Step of processing outer layer copper foil to form surface circuit (e) Step of repeating steps (a) to (d) according to the required number of circuit layers 3. The method for manufacturing a multilayer wiring board according to claim 2, wherein at least one of the resin and the insulating adhesive contains a high thermal conductive inorganic filler.