JPH11112149A - Multilayered printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable multilayered printed wiring board which can be manufactured easily and in which layers are surely connected to each other. SOLUTION: A multilayered printed wiring board is formed by laminating a first substrate composed of conductor foil, or an insulating substrate 11 laminating conductor foil 12 on at least one surface, and having conductive bumps 13 formed on the foil 12, and a second substrate 16 composed of a prepreg 14 which has through holes 15 formed through the prepreg 14 with a laser beam at the positions corresponding to the bumps 13, and press forming the laminated body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer printed wiring board.

[0002]

2. Description of the Related Art In a multilayer printed wiring board, interlayer connection is performed by, for example, through-hole plating. This is done by thermocompression bonding copper foil on both sides of the insulating substrate, drilling copper plating, then forming a resist, then solder plating, peeling off the resist, etching the peeled area, and then soldering. It is manufactured by peeling the plating. However, such a method has a drawback in that it requires steps such as drilling with an NC drill machine, copper plating, solder plating, and peeling of the solder plating, resulting in high costs.

Therefore, recently, a method of connecting between copper conductor layers by using bumps made of conductive paste has been proposed. In this method, as shown in FIG. 2A, a conical bump 2 having a sharp tip is formed on a copper foil 1 formed on the surface of an insulating base material P by silver paste or the like, and a bump of the copper foil is formed. A prepreg 3 made of an insulating resin sheet containing a glass cloth for obtaining strength is arranged on the side of the surface (FIG. 2).
b) After further arranging another copper foil 5 thereon (FIG. 2)
d), these are laminated by pressing while heating and bonded (FIG. 2e), and bumps made of conductive paste penetrate through the prepreg and are joined to the other copper foil to ensure interlayer connection. It is. This method eliminates the need for drilling, plating, and stripping.

[0004]

However, this conductive paper
In the method using a bump made of a strike and an insulating prepreg, there is a possibility that a portion where the bump does not penetrate the prepreg is formed, an insulating material remains between the copper foil and the bump, and connection failure occurs. Therefore, prior to the multi-layer forming press, a bump passing step as shown in FIG. 2C was performed to enhance the management of the shape of the bump and to ensure that the bump penetrates the prepreg. That is, prior to the multi-layer forming press, the pre-heating is performed in advance, and then the hot rolls 4 are passed between the hot rolls 4 as shown in FIG.
Through. However, if the prepreg is heated too much during the bump passing step, the initial properties (such as insulating properties) of the prepreg may be deteriorated.

Further, in this method, dust (contamination) is apt to be generated when the bump penetrates the prepreg, and these adhere to the copper foil surface, impairing the smoothness and causing poor adhesion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable multilayer printed wiring board which can be manufactured simply and has a reliable interlayer connection.

[0007]

A multilayer printed wiring board according to the present invention comprises a conductive foil or an insulating base material having a conductive foil laminated on at least one side, and a conductive bump is formed on the conductive foil. A first base material, a prepreg disposed on the first base material, and a conductor disposed on the prepreg, wherein a through hole is formed by a laser at a location corresponding to the bump. It is characterized in that it is laminated with a second base material made of foil and pressed by multi-layer molding.

The first substrate is a conductor foil such as a copper foil or a conductor foil-clad laminate such as a copper-clad laminate in which a copper foil is laminated on one or both sides of an insulating substrate. Can be. In the case of copper foil, the thickness is, for example, 0.012 mm to 0.01.
It can be 8 mm. In the case of an insulating substrate,
It is made of a paper-based phenol resin substrate or a glass cloth-based epoxy resin substrate, and has a thickness of, for example, 0.06 to 1.1.
mm. The thickness of the conductor foil such as a copper foil formed thereon is, for example, 0.012 to 0.035 mm.

The conductive bump is preferably formed using a conductive paste such as a silver paste, a gold paste, or a copper paste. Used. Although the shape of the bump is free, it is preferable that at least the tip is formed so as to easily enter a through hole provided in the prepreg.

The prepreg may be a sheet made of an insulating resin containing glass cloth or not containing glass cloth, a film, a plate material or the like. For example, an epoxy resin or a fluorine resin can be used as the insulating resin. The thickness of the prepreg may be any thickness as long as the insulating property can be obtained, and is, for example, about 0.04 to 0.2 mm.

A through hole is formed in the prepreg by a laser at a position corresponding to the bump of the first base material. It is made to be able to join. As a laser, short pulse CO ₂
A laser, an excimer laser, a YAG laser, or the like can be used. The size of the through hole depends on the size of the bump that enters it, but at the stage when the multilayer forming press was made,
The size is preferably such that the through holes are completely filled with the bumps.

As the conductive foil constituting the second base material, a copper foil or the like can be used, and the thickness thereof varies depending on the use, but can be, for example, 0.012 mm to 0.018 mm.

[0013] multilayer molding press is performed, for example by vacuum hot pressing varies depending material pressing conditions used, if the prepreg is an epoxy-based resin, for example, a temperature 160 to 180 ° C., a pressure 15~35kg / cm ^2, time It takes 15 to 40 minutes.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
A circuit pattern is formed by a copper foil (thickness: 0.02 mm) 12 on an insulating substrate 11 made of a 0 mm glass cloth base epoxy resin, and the tip of the circuit pattern is sharpened by silver paste. Bump 13 is formed.

The prepreg 14 is made of glass cloth impregnated with an epoxy resin, and has a thickness of 0.1 mm. The prepreg 14 has bumps 1 on the first base material 10.
A through-hole 15 is provided at a position corresponding to 3 by a short pulse CO ₂ laser.

After the prepreg 14 is placed on the first base material 10 and is aligned so that the through holes 15 and the bumps 13 are aligned, a thickness of 0.016
The second base material 16 made of a copper foil having a thickness of 1 mm is placed, and the temperature is 170 ° C. and the pressure is 20 kg / cm ² by vacuum hot pressing.
For 20 minutes (Figure 1d). As a result, the first base material 10 and the second base material 16 adhere to each other, and a laminate 17 in which the bumps 13 of the first base material 10 are completely bonded to the second base material 16 is formed. The second substrate 1 of the laminate 17
A circuit pattern is formed on the substrate 6 by an etching method or the like to form a multilayer printed wiring board.

[0017]

According to the present invention, since the prepreg is previously provided with a through hole into which the bumps of the first base material are inserted by a laser, the bumps of the first base material are formed by a multilayer molding press. Contact is reliably made with the material, and there is no possibility that bumps do not penetrate through the prepreg and a defective connection does not appear as in the prior art, and a reliable interlayer connection is achieved.

Since the through hole is formed by a laser, the hole can be completely formed in a precise, simple and short time in accordance with the size and arrangement of the bumps.

It is also possible to use a prepreg, such as a prepreg containing a glass cloth, which is difficult to penetrate by itself, and it is also possible to use a prepreg having a considerably large thickness. In addition, since there is no step of passing a bump by a hot roll, excessive heat is not applied to the prepreg, so that the characteristics of the prepreg do not deteriorate. In addition, there is no generation of dust from the prepreg when the bump penetrates the prepreg, so that it is possible to reduce a defective rate of a product such as defective bonding.

[Brief description of the drawings]

FIG. 1 is a diagram showing a manufacturing process of a multilayer printed wiring board according to the present invention.

FIG. 2 is a view showing a manufacturing process of a multilayer printed wiring board according to a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 First base material 11 Insulating base material 12 Copper foil (conductor foil) 13 Bump 14 Prepreg 15 Through hole 16 Second base material 17 Laminate (multilayer printed wiring board)

Claims (3)

[Claims] 1. A first base material comprising a conductive foil or an insulating base material having a conductive foil laminated on at least one surface thereof, wherein a first base material having a conductive bump formed on the conductive foil is provided. The laser has a through hole at the corresponding location,
A multilayer printed wiring board formed by laminating a prepreg arranged on a first base material and a second base material made of a conductive foil arranged on the prepreg and performing multilayer forming press. 2. A first base material comprising a copper-clad laminate in which a copper foil is laminated on at least one surface of an insulating substrate and having a conductive bump formed on the copper foil, and a portion corresponding to the bump. A prepreg disposed on a first substrate, which is provided with a through-hole by a laser, and a second substrate made of a copper foil disposed on the prepreg are laminated to form a multilayer forming press. Multi-layer printed wiring board. 3. A first base material having a conductive bump formed on a copper foil and a first base material having a through hole formed by a laser at a position corresponding to the bump. A multilayer printed wiring board obtained by laminating a prepreg disposed on a prepreg and a second base material made of copper foil disposed on the prepreg and performing multi-layer forming press.