JPH057064A - Multilayer printed-circuit board - Google Patents

Abstract

PURPOSE:To provide a multilayer printed circuit board, wherein a thermoplastic resin is used as an insulation base material, and the leads of circuit parts can be subjected to soldering, inserted into through holes. CONSTITUTION:In a multilayer printed circuit board, used is a thermoplastic resin as an insulation layer 1, and on its surface and its inner part, provided are respectively required circuit patterns 2, and further, in the board, bored are holes 3 for inserting the leads of circuit parts, which are passed through the board from its surface to its undersurface. In such a multilayer printed circuit board, specifically, a conductive paste layer 7, whose binder is the thermoplastic resin, is provided on the opening section of the hole 3, which is on the undersurface side of the board, extending from the opening section to a required circuit pattern 2a, with which one end of the conductive paste layer 7 is connected. Further, a land 6 for soldering is so formed on the opening section as to contract its diameter. Also, on the opening section of the hole 3 for inserting the leads of circuit parts, wherein the hole 3 is so bored as to be passed through the board from its surface to its undersurface and the opening section is on the undersurface side of the board, conductive paste layers 5, 6, 7, whose binders are the thermoplastic resins, are so provided as to contract the diameter of the opening section, and as to extend from the opening section to the required circuit pattern 2a, with which one end of the conductive paste layers 5, 6, 7 is connected. Therefore, when inserting the lead of the parts into the hole 3 for inserting the lead of the parts and bonding the lead to the conductive paste layer by soldering, between the lead and the conductive paste layer, the solid junction by soldering is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer circuit board, and more particularly to a multi-layer circuit board using a thermoplastic resin as an insulating base material and having a through hole for inserting a circuit component lead.

[0002]

2. Description of the Related Art Conventionally, multi-layer circuit boards have been widely used in order to respond to downsizing and high functionality of electronic devices and to increase wiring density. Also, as one type of multilayer circuit board, a multilayer circuit board using a thermoplastic resin such as a polycarbonate resin as an insulating base material has been developed. by the way,
A multilayer circuit board using this thermoplastic resin as an insulating base material is manufactured, for example, as follows.

That is, a predetermined circuit pattern is applied on at least one main surface of a thermoplastic resin film with a conductive paste having a thermoplastic resin as a binder, for example, by a screen printing method, and dried to form a plurality of sheets. They are manufactured by combining them and heating and press-bonding them together. Further, in this multilayer circuit board, electrical connection between the outer layer patterns on both surfaces or between the outer layer pattern and the inner layer pattern is made by the following means. That is, a through hole is formed at a predetermined position of a multilayer circuit board that has been heated and pressed, and the inner wall surface of this hole is sequentially subjected to electroless copper plating and electrolytic copper plating to form a conductive film. The plasticity of the thermoplastic resin at the stage of bonding or forming a through hole at a predetermined position of the thermoplastic resin film and interposing a conductive paste in this area This is done by using the deformation to connect the required layers. Further, in this type of multilayer circuit board, the leads of the electronic component are often inserted into the through holes formed in the multilayer circuit board and soldered to a required circuit pattern. In this case, It is necessary to deposit and form a plating layer or the like on the inner wall surface of the through hole through which the lead is inserted so that the solder can easily spread.

[0004]

However, in a multilayer circuit board using such a thermoplastic resin as an insulating base material,
Not only is the work process of forming the plating layer on the inner wall surface of the through hole complicated or complicated, but it is also difficult to control the plating solution and control the plating process. Therefore, in this type of multilayer circuit board, it is difficult to mount the required circuit components by means of inserting the leads of the electronic components into the through holes (through holes) and soldering them, and mounting the components on surface mounting components is difficult. The current situation was limited.

The present invention has been made in order to solve such a problem, and provides a multilayer circuit board which uses a thermoplastic resin as an insulating base material and which can be soldered by inserting leads of circuit parts into through holes. To aim.

[0006]

A multilayer circuit board according to the present invention has a thermoplastic resin as an insulating layer, has a required circuit pattern on the surface and inside, and has lead insertion holes for circuit components penetrating the front and back sides. In a multi-layer circuit board formed by punching, a layer of conductive paste having a thermoplastic resin binder, one end of which is connected to a required circuit pattern, is extended in the back side opening of the lead insertion hole, and the opening is reduced. It is characterized in that a weir for soldering is formed so as to have a diameter.

[0007]

In the multi-layer circuit board of the present invention, one end is connected to a desired circuit pattern so as to reduce the diameter of the opening on the back surface side of the component lead insertion hole which is bored through the front and back. A layer of a conductive paste having a thermoplastic resin as a binder is extended. Therefore, when the component lead is inserted into the component lead insertion hole and soldered, a strong solder joint is formed between the component lead insertion hole and the conductive paste layer, and this layer functions as a weir to prevent the solder from leaking downward. To be prevented.

Further, in the present invention, an outer layer pattern formed of a conductive paste or the like is formed on the back surface of the substrate,
A reliable connection with an inner layer circuit pattern such as a required circuit pattern whose end face is exposed at the opening of the lead insertion hole can be achieved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a general description will be given of the structure of the present invention.

The thermoplastic resin used in the present invention includes electrical insulation, heat resistance, and the like which are usually required for circuit boards.
It is desirable to have various properties such as moisture resistance, and for example, polycarbonate resin, polysulfone resin, polyether sulfone resin, polyacetal resin,
Examples thereof include polyetherketone resin, polyetherimide resin, polyphenyl sulfide resin, polyphenylene oxide resin and the like.

It is desirable that the thermoplastic resin forming the insulating layer of the circuit board and the thermoplastic resin used as the binder of the conductive paste are of the same kind.
A combination of different types may be used as long as they have substantially the same plasticity. Then, the conductive paste is a metal powder such as gold, silver, copper, nickel, tungsten, molybdenum, aluminum or platinum in the thermoplastic resin, or carbon powder, silicon carbide powder, semiconductive powder such as vanadium pentoxide powder. Is added and mixed.

The multilayer circuit board of the present invention can be manufactured, for example, by the following means. That is, first, a required through hole penetrating in the thickness direction is formed at a predetermined position of a substrate (film) made of a thermoplastic resin, and at least one main surface is formed by a method such as printing and applying a conductive paste. Forming a circuit pattern. At this time, it is preferable that the conductive paste is applied and adhered also to the inner wall surface of the through hole.

Then, a plurality of such substrates are stacked so that the corresponding through holes are coaxially arranged.
Heat and pressurize to mold integrally. At this time, one end is connected / extended to a required circuit pattern, and a conductive paste is piled up and applied / adhered to the opening on the back surface side of the through hole formed as the component lead insertion hole.

Further, among the substrates (films) made of the thermoplastic resin described above, the substrate (film) made of the thermoplastic resin laminated on the rearmost side is not provided with through holes,
In addition, a conductive paste layer is provided at a position facing the through hole of the upper layer substrate, these are heated and pressed to be integrally molded, and then a component lead insertion hole is re-drilled at the position of the hole of the obtained multilayer board. By doing so, the conductive paste is caused to flow and rise in the opening on the back surface side of the through hole for inserting the component lead,
It may be left as a weir for soldering.

Further, in the multilayer circuit board of the present invention, an interlayer conduction pad connected to the inner layer circuit pattern is provided in the outer layer, and the interlayer conduction pad and the conductivity provided in the opening of the component lead insertion through hole. The paste layer may be electrically connected by an outer layer pattern formed by printing with a conductive paste. With such a structure, there is an advantage that the connection reliability when soldering the lead insertion part is further improved.

A specific example of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a cross-sectional view showing a main part of a constitutional example of a multilayer circuit board according to the present invention. Reference numeral 1 is an insulation made of a thermoplastic resin such as polycarbonate resin, polysulfone resin or polyethersulfone resin. It is a layer. Then, inside the insulating layer 1, an inner layer circuit pattern 2 made of a conductive silver paste using a low molecular weight polycarbonate resin as a binder is embedded, and at a predetermined position,
Through holes 3 for inserting leads of circuit components are formed to penetrate the front and back.

Of the inner layer circuit pattern 2, for example, the end face of the second layer circuit pattern 2a is exposed on the inner wall surface of the component lead insertion hole 3 described above, and the back surface is formed through the pattern recess 4. Interlayer conduction pad 5 formed on
Connected with. Further, a land 6 made of a conductive paste is provided in the opening on the back surface side of the component lead insertion hole 3 so as to project toward the center of the hole 3 and reduce the diameter of the opening. That is, on the back surface side of the circuit board, the land 6 at the opening of the component lead insertion hole 3 and the interlayer conduction pad 5 are interposed via the outer layer pattern 7 formed of a conductive paste.
And are electrically connected.

In the multi-layer circuit board having the above structure, the structure shown in FIG.
As shown in a sectional view in FIG. 1, when a component lead 8 is inserted into the component lead insertion hole 3 and soldered, a land 6 made of a conductive paste provided in the opening on the back surface side of the insertion hole 3,
A strong and highly reliable solder joint 9 is formed between the lead 8 and the lead 8. That is, the land 6 serves as a weir to prevent the solder from flowing out, the melted solder is reliably held in the insertion hole 3, and is filled in a gap between a part of the inner wall surface and the lead 8. Therefore, a reliable connection is formed.

The land 6 has an inner layer pattern 2 (for example, a second layer pattern) formed through an outer layer pattern 7 formed on the back surface.
Since it is connected to the interlayer conduction pad 5 connected to the circuit pattern 2a) of the layer, the component lead 8 is more reliably connected to the required inner layer pattern 2.

[0021]

As described above, in the multilayer circuit board of the present invention, the conductive material having the thermoplastic resin as a binder, one end of which is connected to the desired circuit pattern, is provided in the opening on the back side of the lead insertion hole of the component to be mounted. Since the paste layer is extended so as to reduce the diameter of the opening, it is easy to solder the leads of the circuit component, and a highly reliable connection such as the lead of the component to be mounted and the inner layer circuit pattern is achieved. obtain.

Further, since a complicated process is not required for manufacturing, the manufacturing yield is high and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a configuration example of a multilayer circuit board according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which circuit components are mounted on the multilayer circuit board diagram shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulating layer made of thermoplastic resin 2 ... Inner layer circuit pattern 3 ... Through hole for lead insertion of component to be mounted 4
... Circuit pattern recess 5 ... Interlayer conduction pad 6 ... Land made of conductive paste 7 ... Outer layer circuit pattern
8 ... Lead of component to be mounted 9 ... Solder

Claims (1)

Claim: What is claimed is: 1. A thermoplastic resin is used as an insulating layer, which has a required circuit pattern on its surface and inside, and
In a multilayer circuit board having lead insertion holes for circuit parts penetrating through the front and back sides, a conductive paste having a thermoplastic resin binder, one end of which is connected to a required circuit pattern, at the back side opening of the lead insertion hole. A multilayer circuit board, wherein layers are extended, and a weir for soldering is formed so as to reduce the diameter of the opening.