JPH07297558A - Circuit board and connection method of terminal to circuit board - Google Patents

Abstract

PURPOSE:To prevent the exfoliation of circuit pattern caused by heating in a terminal connection process. CONSTITUTION:A circuit pattern 11 and a through hole 12, with which the circuit pattern 11 and the adjacently located circuit pattern 9 are connected, are provided through an insulating layer 10. Accordingly, by connecting the circuit pattern 11 and the through hole 12, the exfoliation of the circuit pattern 11 when external force is added to a terminal 13 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board, and more particularly to a structure of a terminal connecting portion and a method of connecting a terminal to a circuit board.

[0002]

2. Description of the Related Art Conventionally, when a terminal is bonded to a circuit board having a circuit pattern formed on the board, it has been conventionally performed as shown in FIG. FIG. 10A is an explanatory diagram for explaining a terminal joining process, and FIG. 10B is an explanatory diagram for explaining a defect after the terminal joining. In (a), 1 is a substrate made of an insulating material, 2 is a circuit pattern formed on the substrate 1,
2a is a land of a circuit pattern to be joined to a terminal to be described later, 3 is a terminal formed in a substantially L shape in a side view, and 4 is a heater. The method shown in FIG. 10 is a method used when the substrate 1 is made of a material having good thermal conductivity, in which the terminals 3 are arranged on the lands 2a of the circuit pattern 2, and the substrate 1 is heated by the heater 4 to about 100 μm. It was preheated to ˜150 ° C., and while supplying the solder 5, the soldering iron 6 was heated and pressed to about 400 ° C. for several seconds to bond the terminal 3 to the land 2a.

However, when the terminals 3 are joined as described above, the temperature of the land 2a becomes high, the adhesion between the circuit pattern 2 near the land 2a and the substrate 1 becomes weak, and the adhesive strength of the adhesive below the land 2a is lowered. Then, when an external force is applied to the terminal 3, the circuit pattern 2 is easily peeled off as shown in (b).

In the layered substrate, the land formed at the portion where the terminal 4 is joined is made to have a size necessary for terminal joining at the end point of the wiring.

[0005]

As described above, in the conventional circuit board, the circuit pattern is peeled off when an external force such as pulling is applied to the terminal 3 after the terminal 3 is soldered to the land 2a. There was a problem.

The present invention has been made in view of the above problems,
An object of the invention is to provide a structure of a circuit board and a method of bonding the terminal to the circuit board, which can prevent the peeling of the circuit pattern due to heating in the terminal bonding step.

[0007]

In order to achieve the above object, a circuit board according to claim 1 is a board in which a plurality of circuit patterns are laminated with an insulating layer interposed therebetween, and a first layer formed on the uppermost part. In the vicinity of the land for joining the terminals of the circuit pattern,
A through hole for joining the first layer circuit pattern and the second layer circuit pattern adjacent to the first layer circuit pattern via the insulating layer is formed.

According to a second aspect of the present invention, there is provided a method of joining terminals to a circuit board, wherein a welding electrode made of a material having good solder wettability is provided on a land for joining terminals of a circuit pattern formed on the board. It has a step of soldering and a step of welding a terminal on the welding electrode.

[0009]

A circuit board according to a first aspect of the present invention is a circuit board in which a plurality of circuit patterns are laminated with an insulating layer interposed therebetween, and the first board is provided near the terminal bonding land of the first layer circuit pattern formed on the uppermost part. Since the layer circuit pattern and the second layer circuit pattern which is adjacent to the first layer circuit pattern via the insulating layer are joined via the through holes, the peel strength of the first layer circuit pattern is increased. In other words, by increasing the area of the land for terminal bonding of the circuit pattern and forming the through hole at a position on the land that does not hinder terminal bonding, even if force is applied to the terminal in the pulling direction after soldering. The through holes enhance the adhesion of the circuit pattern to the substrate and prevent the circuit pattern from peeling.

In a circuit board according to a second aspect, a welding electrode (a material having good solder wettability and conductivity such as Cu plated with Ni) is soldered to a land for joining terminals, and the welding is performed. Since the electrode and the terminal are connected by welding, the temperature in the vicinity of the land does not become high at the time of joining the terminal, and the circuit pattern does not easily peel off from the substrate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the circuit board of the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing the structure of a terminal joint portion of a circuit board. In the figure, the circuit board has an insulating layer 8 formed on a base substrate 7 made of Al which is a substrate, and a circuit pattern 9 which is a second layer circuit pattern formed on the insulating layer 8 and then The insulating layer 10 and the circuit pattern 11, which is the first layer circuit pattern, are formed on the upper portion, and the circuit pattern 11 is formed.
Through hole 12 for joining the circuit pattern 9 and the circuit pattern 11 near the lower portion of the land 11a for joining terminals
Is formed. With this structure, even if an external force is applied to the terminal 13 that is joined to the land 11a by the solder 14 and is substantially L-shaped in a side view, the circuit pattern 1 is formed.
1 becomes difficult to peel off.

A different embodiment of the circuit board of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view showing an embodiment of a circuit board in which a double-sided glass epoxy substrate having circuit patterns formed on both sides is bonded onto a substrate having a circuit pattern formed on one side. In FIG. 2, the circuit board has an insulating layer 16 formed on an Al base substrate 15 which is a substrate.
A double-sided glass epoxy substrate in which a lower layer circuit pattern 19 or an upper layer circuit pattern 20 to be the second layer circuit pattern is formed on both sides of the glass epoxy base 18 on the substrate on which the circuit pattern 17 which is the second layer circuit pattern is formed. It is glued. In addition, the circuit pattern 17 and the circuit pattern 2 are provided in the vicinity of the land 20a for joining the terminals of the circuit pattern 20.
A through hole 21 is formed to join with 0.

A further different embodiment of the circuit board of the present invention is shown in FIG. FIG. 3 is a plan view showing the surface structure of the circuit board. In the figure, 22 is an insulating layer, 23 is a circuit pattern which is a first layer circuit pattern, and 23a is a land for terminal bonding. Further, 24 is a through hole formed in the lower portion of the outer edge of the land 23a. As described above, the effect can be further enhanced by forming a plurality of through holes 24.

Further, in the circuit board shown in FIG. 1, if the through hole is formed immediately below the land 11a for joining the terminals as shown in FIG. 4, the mounting area on the circuit board by forming the through hole 12 is reduced. The decrease can be prevented. Further, in the circuit board shown in FIG. 3, instead of the through hole 24 formed at the outer edge of the circuit pattern, as shown in FIG. 5, through holes 25 are formed before and after the terminal joining position 23b of the land 23a. It is also possible to increase the peel strength.

Further, as shown in FIG. 6, a land 27 having a substantially rectangular shape of a circuit pattern 27 formed on the insulating layer 26.
The peel strength can be increased by forming the through holes 28 at the four corners of a.

FIG. 7 shows a further different embodiment of the present invention. The circuit board shown in FIG. 7 is provided only for preventing the peeling of the circuit pattern 32, which is the first layer circuit pattern formed on the insulating layer 31, in addition to the circuit pattern 30 used as a conductive path on the substrate 29. , The circuit pattern 33 (dummy circuit pattern) which becomes the second layer circuit pattern is formed on the land 32.
The through hole 34 is formed below the circuit pattern 33 and between the circuit pattern 33 and the land 32a to enhance the peel strength of the circuit pattern 32.

A different embodiment of the circuit board of the present invention will be described with reference to FIG. In FIG. 8, 35 is a substrate, 36 is an insulating layer, 37 is a circuit pattern, 37a is a land for joining terminals, 38 is solder, 39 is a welding electrode composed of a material having good solder wettability and conductivity, 40 Is a terminal,
41 is a heater.

Next, a method of joining terminals to the circuit board shown in FIG. 8 will be described with reference to FIG. First, as shown in (a), 100 to 200 is placed on an Al substrate 35 having a thickness of 2 to 3 mm.
A circuit board on which an insulating layer 36 of μm is formed, and a circuit pattern 37 of copper foil of about 100 μm is formed on the insulating layer 36. Solder 38 is used by screen printing to solder lands 37a for terminal connection and other mounting components 42. It is applied to a land (reference numeral omitted), and thereafter, for example, a welding electrode 39 and a mounting component 42, which have Ni plating on Cu to improve solder wettability, are arranged at respective predetermined positions, and solder joining is performed. Next, as shown in (b), the electrodes 43a and 43b from the power source 43 are connected to the welding electrode 39 and the terminal 40, respectively, a current is passed between the welding electrode 39 and the terminal 40, and the Joule heat locally causes the current to flow. About
The temperature is raised to 1000 ° C. and the welding electrode 39 and the terminal 40 are welded. By joining the terminals by the method described above,
Since the temperature rise of the land 37a for joining terminals can be suppressed, it is possible to prevent the adhesion of the circuit pattern 37 to the insulating layer 36 from decreasing and the peeling of the circuit pattern 37 from occurring. Further, since the welding electrode can be connected to the circuit board by reflow at the same time as other mounting components, an extra step is not added.

The circuit patterns and the shapes of the welding electrodes are not limited to those in the embodiment. Further, the position where the through hole is provided is not limited to the example.

[0020]

As described above, according to the circuit board of the first aspect, by peeling off the circuit pattern when an external force is applied to the terminal, by bonding the circuit pattern bonded to the terminal and the through hole. Can be prevented.

According to the method of joining terminals to the circuit board of the second aspect, the land of the circuit pattern and the welding electrode are joined by solder, and the terminal and the welding electrode are joined by welding. The temperature rise can be suppressed,
It is possible to prevent peeling of the circuit pattern.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a circuit board of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the circuit board of the present invention.

FIG. 3 is a sectional view showing a further different embodiment of the circuit board of the present invention.

FIG. 4 is a sectional view showing still another embodiment of the circuit board of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the circuit board according to the present invention.

FIG. 6 is a sectional view showing still another embodiment of the circuit board of the present invention.

FIG. 7 is a sectional view showing still another embodiment of the circuit board of the present invention.

FIG. 8 is a cross-sectional view showing an embodiment of a circuit board configured by using the method of joining terminals to the circuit board of the present invention.

FIG. 9 is a cross-sectional view showing an example of a method of joining terminals to a circuit board according to the present invention.

FIG. 10 is a cross-sectional view showing an example of a conventional method of joining terminals to a circuit board.

[Explanation of symbols]

11, 20a, 23, 27, 32 First layer circuit pattern 10, 18, 31 Insulating layer 11a, 20a, 23a, 27a, 32a, 37a Land 9, 17, 33 Second layer circuit pattern 12, 21, 25, 28 , 34 through hole 39 welding electrode 35 substrate 37 circuit pattern 37a land 40 terminal

Claims (2)

[Claims] 1. A substrate in which a plurality of circuit patterns are laminated via an insulating layer, wherein the first layer circuit pattern is provided in the vicinity of a land for terminal bonding of the first layer circuit pattern formed on the uppermost portion, A circuit board having a through hole for joining the first layer circuit pattern and the second layer circuit pattern adjacent to each other through the insulating layer. 2. A step of soldering a welding electrode made of a material having good solder wettability and conductivity on a land for joining terminals of a circuit pattern formed on a substrate, and the step of forming a solder on the welding electrode. A method of joining terminals to a circuit board, the method comprising: welding the terminals.