JPH08153971A - Multilayered printed wiring board and its manufacture - Google Patents

Abstract

PURPOSE: To provide a multilayered printed wiring board in which the metallic wiring patterns of the laminated boards constituting the wiring board can be surely electrically connected to each other. CONSTITUTION: A through hole is formed through a multilayered wiring board Bl manufactured by laminating a plurality of boards 101a-101c carrying metallic wiring patterns 102a-102d on their surfaces upon another by successively and continuously changing the diameter of the through hole from ϕa to ϕc at every board 101a-101c and the through hole is filled with conductive paste 106 over the full depth of the through hole from the surface of the board 101a to the bottom of the board 101c.

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 manufactured by laminating a plurality of laminated boards and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, by laminating a plurality of laminated plates corresponding to a single-layer printed circuit board and integrally press-molding, the wiring density is significantly improved as compared with a single-layer printed circuit board. Multilayer printed wiring boards exist.

In such a conventional multilayer printed wiring board, a means for connecting the metal wiring patterns on the surface of each laminated plate to each other among the laminated plates is, in one step of the manufacturing process, the multilayer printed wiring board. A connection means has been adopted in which a through hole is formed at a stretch in the thickness direction of a wiring board and the inner surface of the through hole is subjected to conductive plating.

As a general method for producing a multilayer printed wiring board A, "Handbook of Electrical and Electronic Materials" (published by Asakura Shoten: 1987), pages 150 to 164,
(1) Etched foil method and (2) Additive method are described as typical methods.

In the following description, the most commonly adopted (1) conventional manufacturing process of a multilayer printed wiring board using the etched foil method will be described with reference to the drawings. The etched foil method is a method in which a metal-clad laminate is used as a substrate, excess metal foil is removed by etching to form a metal wiring pattern, and then the metal-clad laminate is laminated and integrally formed.

FIG. 4 is a side sectional view showing a structure of a conventional multilayer printed wiring board using an etched foil method before a laminating step, FIG. 5 is a side sectional view showing a structure after the laminating step, and FIG. It is a sectional side view which shows the structure after the same conductive plating process.

In the figure, A is a multilayer printed wiring board, 1a-
1c is a laminated plate, 2a to 2d are metal wiring patterns, 3a,
3b is a prepreg, 4 is a through hole, and 5 is a through hole plating.

A metal foil is pre-deposited on the entire upper surface of each of the laminated plates 1a and 1b.
Metal foils are pre-deposited on the entire top surface and the entire bottom surface. The prepregs 3a and 3b are obtained by impregnating an insulating base material with a thermosetting adhesive, and are laminated plates 1a to 1c.
Have the role of adhering to each other.

In the first step, the metal foil adhered to each of the laminated plates 1a to 1c is etched into a desired circuit wiring pattern, and the metal wiring patterns 2a to 2 are respectively formed.
to form d.

In the second step shown in FIG. 5, alignment is performed, and the laminated plate 1a, the prepreg 3a, the laminated plate 1b, the prepreg 3b, and the laminated plate 1c are sequentially superposed to form the laminated plate 1a.
Through holes 4 having a constant diameter φ are formed at a stretch from the front surface side or the bottom surface side of the laminated plate 1c.

In the third step shown in FIG. 6, the laminated plates 1a to 1c and the prepregs 3a and 3b which are superposed on each other are
It is compressed in the thickness direction, heated at a temperature and for a time sufficient to cure the thermosetting adhesive, and bonded and integrally molded.

In the fourth step shown in FIG. 7, the inner surface 4a of the through hole 4 is subjected to a conductive plating treatment to form a conductive plating layer 5, or the inside 4b of the through hole 4 is deposited.
The metal wiring patterns 2a to 2d are electrically connected to each other by filling the conductive paste 6 into the metal wiring patterns 2a to 2d.

The conventional laminated printed circuit board A is manufactured by such a manufacturing method, and the diameter φ of the through hole 4 is exactly the same in each of the laminated plates 1a to 1c.

[0014]

However, the above-mentioned conventional multilayer printed wiring board A has the through hole 4
Since the diameter φ was exactly the same in each layer 1a, 1b, 1c, the shape of the contact surfaces 2b1, 2c1 of the inner layer metal wiring patterns 2b, 2c to the inner surface 4a of the through hole 4 is the same as the inner layer metal wiring pattern 2b. , 2c was very thin, and it was annular.

That is, the metal wiring pattern 2b of the inner layer,
The contact area between the contact surfaces 2b1 and 2c1 and the conductive plating layer 5 in 2c was very small, and the contact resistance was high.
Further, when the fabrication processing accuracy is low, smear occurs on the contact surfaces 2b1 and 2c1 of the metal wiring patterns 2b and 2c, or reliable electrical contact cannot be ensured, so that the multilayer printed wiring board A itself. The quality and reliability of were poor.

Attractingly, there is a drawback that the yield of the multi-layered printed wiring board A is lowered and, as a result, the production cost is increased. Here, an object of the present invention is to provide a multilayer printed wiring board and a method for manufacturing the same, in which the electrical connection of the metal wiring patterns between the respective laminated plates is reliable.

[0017]

In order to achieve the above-mentioned object, the present invention employs the concrete constituent means and methods listed below. That is, the first feature of the means of the present invention is, in a multilayer printed wiring board manufactured by laminating a plurality of laminated plates having a metal wiring pattern formed on the surface thereof, a through hole diameter is sequentially set for each of the plurality of laminated plates. This is a multilayer printed wiring board in which through holes are formed by being continuously changed and the through holes are filled with a conductive paste across the plurality of laminated plates.

In other words, the second feature of the means of the present invention is a multilayer printed wiring board manufactured by laminating a plurality of laminated plates having a metal wiring pattern formed on the surface thereof, and a through hole for each of the plurality of laminated plates. This is a multilayer printed wiring board in which through holes are formed through which diameters are sequentially and continuously changed and conductive plating treatment is performed on the inner surface of the through holes across the plurality of laminated plates.

A first feature of the method of the present invention is that a desired metal wiring pattern is formed on each of a plurality of laminated plates having a metal foil adhered on the surface thereof, and a prepreg is provided between each of the plurality of laminated plates. By sandwiching, the laminated plate of each layer and the prepreg of each layer are integrally formed, through holes are formed while sequentially changing the through hole diameter in the thickness direction, and the laminated plate of each layer and the prepreg of each layer are laminated. This is a method for manufacturing a multilayer printed wiring board in which the through holes are filled with a conductive paste after being bonded and integrally molded.

The second feature of the method of the present invention is that a desired metal wiring pattern is formed on each of a plurality of laminated plates having a metal foil adhered on the surface thereof, and a prepreg is provided between each of the plurality of laminated plates. By sandwiching, the laminated plate of each layer and the prepreg of each layer are integrally formed, through holes are formed while sequentially changing the through hole diameter in the thickness direction, and the laminated plate of each layer and the prepreg of each layer are laminated. This is a method for manufacturing a multilayer printed wiring board in which the inner surface of the through hole is subjected to conductive plating after being bonded and integrally molded.

[0021]

Embodiments of the present invention will be described with reference to the drawings. A multilayer printed wiring board of the first embodiment of the present invention using the etched foil method and a method of manufacturing the same will be described.

FIG. 1 is a cross-sectional view showing the structure of the multilayer printed wiring board of this embodiment before the laminating step, FIG. 2 is a cross-sectional view showing the same structure after the laminating step, and FIG. 3 is the same conductive paste filling. It is a cross-sectional view showing the structure after the process.

In the figure, B1 is a multilayer printed wiring board, 10
1a to 101c are laminated plates, 102a to 102d are metal wiring patterns, 103a and 103b are prepregs, and 104.
Is a through hole, and 106 is a conductive paste.

In the multilayer printed wiring board B1 of this embodiment shown in FIG. 1, the laminated plates 101a to 101c of the respective layers are
Similar to the conventional example, it is made of a material such as paper-phenolic resin, paper-epoxy resin, glass-epoxy resin, and the like, and the laminated plates 101a and 101b have metal foils pre-deposited on their entire upper surfaces. In the laminated plate 101c, metal foils are pre-deposited on the entire upper surface and the entire bottom surface. Similar to the conventional example, the prepregs 103a and 103b are made by impregnating a thermosetting adhesive in an insulating base material and have a role of adhering the laminated plates 101a to 101c to each other.

In the first step, the laminated plates 101a to 10a.
The metal foil deposited on 1c is etched into a desired circuit wiring pattern by a known etching method to form metal wiring patterns 102a to 102d, respectively.

In the second step shown in FIG. 1, alignment is performed and the laminated plate 101a, the prepreg 103a and the laminated plate 10 are aligned.
1b, the prepreg 103b, and the laminated plate 101c are drilled in this order so that the diameters φa, φb, and φc of the through holes 104 increase or decrease sequentially.

In the third step shown in FIG. 2, the laminated plate 101 after the perforation step is completed by the subsequent positioning.
a, the prepreg 103a, the laminated plate 101b, the prepreg 103b, and the laminated plate 101c are laminated in this order, compressed in the thickness direction, heated at a temperature and for a time sufficient for the thermosetting adhesive to cure, and then bonded and integrally molded. To do.

In the laminated multilayer printed wiring board B1 shown in FIG. 2 manufactured in this way, the contact surface 102b is formed in the through hole 104 of the multilayer printed wiring board B1 in which the laminated plates 101a, 101b and 101c of the respective layers are laminated.
1,102c1 is exposed.

In the fourth step shown in FIG. 3, the conductive paste 106 is filled in the through holes 104 to electrically connect the metal wiring patterns 102a to 102d to the contact surfaces 102a1 to 102d1, respectively. As the material of the conductive paste 106, gold, silver, copper, other conductive materials, a mixed material in which these are mixed at an arbitrary ratio, a mixed material in which various low melting point metals are mixed, and the like can be used. .

At this time, the surface areas of the contact surfaces 102b1 and 102c1 of the inner layer metal wiring patterns 102b and 102c exposed to the through hole inner surface 104a are significantly larger than the surface areas of the contact surfaces 2b1 and 2c1 in the conventional example. Since it increases, the contact resistance decreases.

In the present embodiment, as a result of adopting such a concrete constitution means and method, the multilayer printed wiring board has a different through hole diameter in each layer, so that the contact surface of the inner layer metal wiring pattern to the through hole is The donut disk shape is formed, and the contact between the metal wiring pattern and the conductive paste is expanded to a substantially surface contact, so that electrical connection is ensured.

Second aspect of the present invention using the etched foil method
A multilayer printed wiring board of the embodiment and a method for manufacturing the same will be described. 1 is a cross-sectional view showing the structure of the multilayer printed wiring board of this embodiment before the laminating step, FIG. 2 is a cross-sectional view showing the structure of the same after the laminating step, and FIG. 4 is the same after the through-hole plating step. It is a cross-sectional view showing the structure of.

In the figure, B2 is a multilayer printed wiring board, 10
Reference numeral 5 is a conductive plating layer. The same components as those in the first embodiment are designated by the same reference numerals. The material of each part of the multilayer printed wiring board B2 of this embodiment shown in FIG. 4 is the same as that of the first embodiment.

In the first step, the laminated plates 101a to 101c are used.
The metal foil deposited on the substrate is etched into a desired circuit wiring pattern by a known etching method to form metal wiring patterns 102a to 102d, respectively.

In the second step shown in FIG. 1, alignment is performed and the laminated plate 101a, the prepreg 103a, and the laminated plate 10 are aligned.
The holes 1b, the prepreg 103b, and the laminated plate 101c are drilled in this order so that the diameters φa, φb, and φc of the through holes 104 increase or decrease sequentially.

In the third step shown in FIG. 2, the laminated plate 101a and the prepreg 103a, the laminated plate 101b and the prepreg 103b, and the laminated plate 101c, which have undergone the perforating step, are laminated in this order, compressed in the thickness direction, and thermoset adhesive. The agent is heated at a temperature and for a time sufficient for the agent to cure, and is integrally molded.

In the thus manufactured multilayer printed wiring board B2 after the laminating step shown in FIG. 2, the contact surface 102b1 is formed in the through hole 104 of the multilayer printed wiring board B2 in which the laminated plates 101a to 101c of the respective layers are laminated. 1
02c1 is exposed.

In the fourth step shown in FIG. 4, the inner surface 104a of the through hole 104 is subjected to a conductive plating treatment to form a conductive plated layer 105, so that the metal wiring patterns 102a to 102d are brought into contact with the contact surfaces 102a1 to 102a.
2d1 electrically connect to each other. In forming the conductive plating layer 105, any plating material and plating method such as electroplating or electroless plating generally used for printed wiring boards can be applied.

At this time, the surface areas of the contact surfaces 102b1 and 102c1 of the metal wiring patterns 102b and 102c of the inner layer exposed to the inner surface 104a of the through hole are significantly larger than the surface areas of the contact surfaces 2b1 and 2c1 in the conventional example. Since it increases, the contact resistance decreases.

In the present embodiment, as a result of adopting such a concrete constitution means and method, the multilayer printed wiring board has a different through hole diameter in each layer, so that the contact surface of the inner layer metal wiring pattern to the through hole is The donut disk shape is formed, and the contact between the metal wiring pattern and the conductive plating layer is expanded to a substantially surface contact, so that electrical connection is ensured.

In the first and second embodiments, the through hole diameter of each layer is increased or decreased from one side to the other side in the thickness direction of the multilayer printed wiring boards B1 and B2. It is also possible to increase or decrease from each side to both sides, and the like.

[0042]

As described above, in the multilayer printed wiring board of the present invention, the contact area of the inner layer metal wiring pattern with the inner surface of the through hole is significantly increased as compared with the conventional multilayer printed wiring board. Therefore, the contact resistance between the metal wiring patterns of each layer is reduced, and there is an effect of ensuring reliable electrical contact.

Further, the multi-layer printed wiring board prepared by filling the conductive paste described in the first embodiment is processed in comparison with the conventional multi-layer printed wiring board prepared by conducting conductive plating. However, as an alternative to omitting the conductive plating process which is complicated and expensive, it can be realized by a conductive paste filling process that can be performed more easily and cheaply, which can reduce the material cost and manufacturing cost and is excellent in economic efficiency. At the same time, since the material of the conductive paste can be arbitrarily selected, the degree of freedom in selecting the material during production is high.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a multilayer printed wiring board according to first and second embodiments of the present invention before a laminating step.

FIG. 2 is a transverse cross-sectional view showing the structure after the above-mentioned lamination process.

FIG. 3 is a cross-sectional view showing the structure of the multilayer printed wiring board according to the first embodiment of the present invention after the conductive paste filling step.

FIG. 4 is a cross-sectional view showing the structure of the multilayer printed wiring board according to the second embodiment of the present invention after the through-hole plating process.

FIG. 5 is a cross-sectional view showing a structure of a conventional multilayer printed wiring board before a laminating step.

FIG. 6 is a transverse cross-sectional view showing the structure after the above-mentioned laminating step.

FIG. 7 is a transverse cross-sectional view showing the structure after the above-mentioned through-hole plating treatment step.

[Explanation of symbols]

 A, B1, B2 Multilayer printed wiring board 1a to 1c, 101a to 101c Laminated boards 2a to 2d, 102a to 102d Metal wiring pattern 3a, 3b, 103a, 103b Prepreg 4, 104, 104 Through hole 5, 105 Conductive plating layer 106 Conductive paste

Claims (4)

[Claims] 1. A multilayer printed wiring board manufactured by laminating a plurality of laminated plates having a metal wiring pattern formed on the surface thereof, wherein the through holes are successively and continuously changed for each of the plurality of laminated plates. And a conductive paste is filled inside the through hole across the plurality of laminated plates. 2. A multilayer printed wiring board produced by laminating a plurality of laminated plates having a metal wiring pattern formed on the surface thereof, wherein the through hole diameter is sequentially and continuously changed for each of the plurality of laminated plates. A multilayer printed wiring board having a through-hole formed therein, and an inner surface of the through-hole is subjected to a conductive plating treatment between the plurality of laminated plates. 3. A desired metal wiring pattern is formed on each of a plurality of laminated plates having a metal foil adhered on the surface thereof, and a prepreg is sandwiched between each of the plurality of laminated plates. After integrally forming the prepreg of each layer, through holes are formed while sequentially changing the through-hole diameter in the thickness direction continuously, after laminating the prepreg of each layer and the prepreg of each layer and adhering them integrally, A method for manufacturing a multilayer printed wiring board, characterized in that the inside of the through hole is filled with a conductive paste. 4. A desired metal wiring pattern is formed on each of a plurality of laminated plates having a metal foil deposited on the surface thereof, and a prepreg is sandwiched between each of the plurality of laminated plates to form a laminated plate of each layer. After integrally forming the prepreg of each layer, through holes are formed while sequentially changing the through-hole diameter in the thickness direction continuously, after laminating the prepreg of each layer and the prepreg of each layer and adhering them integrally, A method for manufacturing a multilayer printed wiring board, characterized in that an inner surface of the through hole is subjected to a conductive plating treatment.