JPH1056244A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ease the connection of circuit components with a thick conductor of circuit board through soldering. SOLUTION: A thick conductor 2 that is a specified punched pattern of a metallic plate is adhered to an insulation substrate 1 with adhesives 6, etc. On the other hand, a terminal pattern 3 is formed at the end part of the conductor 2 on the substrate 1, by pattern-etching a metallic foils in a manner that it may overlap the conductor 2 partly in contact therewith. Then, the conductor 2 and pattern 3 are connected electrically with each other through solder 5 and 5, etc., put into holes which are formed in the conductor 2. The circuit components are connected to the pattern 3 by soldering after their lead terminals are inserted to through holes 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board in which a conductor for a power circuit through which a relatively large current flows is arranged on an insulating substrate.

[0002]

2. Description of the Related Art Servo motor control boards, etc.
A composite circuit board has been used in which a signal conductor through which a control signal flows and a thick power circuit conductor through which a large current flows are arranged on the same substrate.

FIG. 4 is a view showing a part of a conventional composite circuit board. FIG. 4A is a plan view and FIG. 4B is a sectional view of a main part. In FIG. 4, 1 is an insulating substrate, 2 is a thick conductor, 8 and 9 are signal conductors, 20 and 22 are pattern conductors,
21 is a solder plating layer, 23 is a through hole, and 24 is a burring portion.

The insulating substrate 1 is made of glass epoxy or the like, and a copper foil adhered to the surface thereof, for example, a copper foil of about 35 μm is etched into a predetermined pattern so that the signal conductors 8 and 9 and the pattern conductor 20 are formed on the surface. Is formed. The thick conductor 2 for large current is formed by punching a copper plate having a thickness of 1 to 2 mm into a predetermined pattern, and is attached by soldering to the pattern conductor 20 etched in the same shape.

The through hole 23 is formed by inserting a burring portion 24 formed by squeezing a part of the thick conductor 2 into a cylindrical shape by burring into a hole formed in the insulating substrate 1. Is formed by soldering to the patterned conductor 22 formed in the above. Circuit components such as thyristors and power transistors are connected to the through holes 23 by screwing or the like.

A conventional document relating to such a composite circuit board is disclosed, for example, in JP-A-63-237495.
(G07F 9/00).

[0007]

However, the above-mentioned conventional circuit board has a problem that circuit parts such as a power transistor cannot be directly connected to the thick conductor 2 by soldering.

[0008] When the current capacity exceeds 50 A, most of the circuit components are of the screw connection type. Such circuit components can be connected to the thick conductor 2 of the conventional circuit board described above. . However, in the case of a circuit component having a current capacity of about 20 A to 40 A, the terminal size is so small that it is difficult to form a screwed structure. When such a solder connection type circuit component is to be connected to the thick conductor 2 as described above, the heat capacity of the thick conductor 2 is large and the heat is quickly diffused during the soldering operation, so that the soldering is difficult. It is.

An object of the present invention is to solve such a problem and facilitate soldering connection to a thick conductor on a circuit board.

[0010]

According to a first aspect of the present invention, there is provided a circuit board comprising: a metal foil pattern provided on an insulating substrate; A circuit board provided with a thick conductor 2;
The metal foil pattern includes a terminal pattern 3 that partially overlaps and contacts the thick conductor 2 at a position where the thick conductor 2 is located.
And electrically connecting the thick conductor 2 and the terminal pattern 3 to each other.
By providing such a terminal pattern 3, connection of the circuit component to the thick conductor 2 can be easily performed by soldering connection.

Further, the circuit board according to the present invention is characterized in that a metal foil is separated between the terminal patterns 3 and 3. Thus, by separating the metal foil between the respective terminal patterns 3 and 3,
Since all the current flows through the thick conductor 2, the pattern conductor does not overheat.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing the first embodiment. In FIG. 1, reference numerals 1, 2, 8, and 9 correspond to those in FIG. 4, 3 is a terminal pattern, 4 is a through hole, 5 is a bonding solder, 6 is an adhesive, and 7 is a bolt hole.

In the present invention, the metal foil attached to the insulating substrate 1 is subjected to pattern etching to provide a metal foil pattern such as the terminal pattern 3, the signal conductors 8, 9 and the like. The thick conductor 2 is formed by punching a copper plate of oxygen-free copper or tough pitch copper having a thickness of about 1 mm, which is slightly thinner than a conventional one, into a required pattern. Terminal pattern 3
Is partially in contact with the end of the thick conductor 2,
Further, the thick conductors 2 are electrically connected to each other by the bonding solder 5 poured into the holes formed at the ends of the thick conductors 2. Further, the terminal pattern 3 is formed with a through hole 4 penetrating the insulating substrate 1 and having a solder plating layer formed on an inner surface thereof, so that terminals of circuit components such as a power transistor can be inserted into the through hole 4 and soldered. .

The thick conductor 2 is fixed to the insulating substrate 1 by a thermosetting adhesive 6 having heat resistance enough to withstand heat when the circuit board is immersed in a solder bath to solder circuit components. ing. The bolt hole 7 is for directly screw-connecting the power module or the like to the thick conductor 2, and a hole having the same diameter is formed through the insulating substrate 1 and the thick conductor 2. The portion of the bolt hole 7 may have the same structure as the burring portion 24 shown in the conventional example.

In the example shown in FIG. 1, the thick conductor 2 is formed of a single plate conductor. However, as shown in FIG.
You may form by laminating 1-2. In this case, the plate conductors 2-1 and 2-2 may be bonded with an adhesive or with solder. By laminating a plurality of plate conductors in this way, the current capacity can be increased as the number of laminated layers increases.

FIG. 3 is a diagram showing a third embodiment. In FIG. 3, reference numerals 1 to 4 correspond to those in FIG.
0 and 13 are pattern conductors, 10a and 10b are pattern cut portions, 11 is a rivet for connecting the thick conductor 2 and the terminal pattern 3, 12 is a thick conductor on the back surface of the insulating substrate,
14 is a joining solder, 15 is a branch conductor, and 16 is a through hole.

The metal foil attached to the surface of the insulating substrate 1 is subjected to pattern etching to form a metal foil pattern including the terminal pattern 3, the pattern conductor 10, and the branch conductor 15. On top of this, a thick conductor 2 formed by punching a copper plate into a required pattern is overlapped to form a pattern conductor 1.
0 and the thick conductor 2 are bonded by solder.

The pattern conductor 10 has at least one pattern cutting portion 10 between the terminal patterns 3 at both ends.
a and 10b are provided. Such a pattern cutting part 1
The reason why 0a and 10b are provided is as follows. That is, if such pattern cut portions 10a and 10b are not provided, a parallel circuit is formed by the pattern conductor 10 and the thick conductor 2. In one of the circuits, the terminal pattern 3-the thick conductor 2-the terminal pattern 3, a contact resistance is generated at the connection portion between the terminal pattern 3 and the thick conductor 2, and the entire electric resistance is reduced. It becomes larger than the electrical resistance of the circuit of the three-pattern conductor 10 and the terminal pattern 3. As a result, most of the current flows through the pattern conductor 10, and the pattern conductor 10 is overheated, causing an unexpected accident. In order to avoid this, pattern cut portions 10a and 10b are formed in the pattern conductor 10 so that current does not flow through the pattern conductor 10 and all current flows through the thick conductor 2. By doing so, the pattern conductor 10 will not be overheated. On the other hand, even if a small amount of heat is generated in a portion where the contact resistance of the connection between the terminal pattern 3 and the thick conductor 2 is present, the heat is transferred to the thick conductor 2.
There is no particular problem because it is absorbed by

In this embodiment, the pattern conductor 1
The width of the thick conductor 2 is smaller than the width of the thick conductor 2. However, when the thick conductor 2 is bonded to the pattern conductor 10, even if the position of the thick conductor 2 is slightly shifted, The pattern conductor 10 does not appear on the surface. In addition, by directly fixing the thick conductor 2 and the insulating substrate 1 at a portion protruding from the pattern conductor 10 with a heat-resistant adhesive, the bonding strength can be stabilized.

The branch conductor 15 is used for shunting a small current from the terminal pattern 3 and detecting the voltage of the terminal pattern 3. This branch conductor 15
Is formed integrally with the terminal pattern 3, so that shunting and voltage detection can be performed without contact resistance.

In the present invention, the means for fixing the thick conductor 2 to the insulating substrate 1 is not particularly limited. However, as described in the above embodiment, the thick conductor 2 is formed by using a heat-resistant adhesive that can withstand soldering. It is desirable that the thick conductor 2 be directly fixed to the insulating substrate 1. That is, the pattern conductor formed on the surface of the insulating substrate 1 is usually subjected to solder plating to prevent oxidation. However, when the thick conductor 2 is solder-plated and fixed, the soldering of the component is performed by soldering. When immersing in a bath, the solder plating may be melted and the thick conductor 2 may be peeled off. The same applies to the case where the thick conductor 2 and the solder-plated pattern conductor are bonded with a heat-resistant adhesive. On the other hand, if the thick conductor 2 is directly fixed to the insulating substrate 1 with an adhesive having solder heat resistance (without interposing a solder plating layer), the thick conductor 2 is peeled off even when immersed in a solder bath. Such a thing disappears. Such a method of fixing the thick conductor 2 is particularly desirable when the thick conductor 2 is provided on both sides of the insulating substrate.

[0022]

As described above, according to the circuit board of the present invention, the terminal pattern 3 is formed so as to partially contact the thick conductor 2 on the insulating substrate where the end of the thick conductor 2 is located.
Was formed, and the terminals of the circuit components were connected thereto. As a result, connection of the circuit component to the thick conductor can be easily performed by soldering. Further, if the metal foil is separated between the respective terminal patterns 3, all the current flows to the thick conductor 2 and the pattern conductor does not overheat.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment.

FIG. 2 is a diagram showing a second embodiment.

FIG. 3 is a diagram showing a third embodiment;

FIG. 4 is a diagram showing a part of a conventional composite circuit board;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating board 2,12 Thick conductor 3 Terminal pattern 4,16,23 Through hole 5,14 Bonding solder 6 Adhesive 7 Bolt hole 8,9 Signal conductor 10,13,20,22 Pattern conductor 11 Rivet 15 Branch conductor 21 Solder plating layer 24 Burring section

Claims (2)

[Claims] 1. A circuit board comprising: a metal foil pattern provided on an insulating substrate (1); and a thick conductor (2) obtained by processing a metal plate into a required pattern on the metal board. The pattern has a terminal pattern (3) that partially overlaps and contacts the thick conductor (2) at a position where the thick conductor (2) is located, and the thick conductor (2) And a terminal pattern (3) electrically connected to the circuit board. 2. The circuit board according to claim 1, wherein a metal foil is separated between each of the terminal patterns (3).