JPH10178248A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the heat capacities at terminal sections in a circuit pattern by providing constrictions which suppress the heat conduction between the terminal sections and wiring sections connected to the terminal sections between the terminal and wiring sections. SOLUTION: Constrictions 6 are provided between terminals A-D and wiring sections 5 so as to suppress heat conduction to a pattern 9 from the terminals A-D, with the constrictions 6 between the terminals A and B and the sections 5 being provided with wavy sections 7 formed by bending the constrictions 6 several times. Since the widths of the heat conducting paths for diffusing heat given to terminals sections 4 become narrower and the heat radiation through the circuit pattern 9 is suppressed, the temperature rise efficiency at the terminal sections 4 can be raised. In addition, since the lengths of the constrictions 6 between the terminals A and B and the wiring sections 5 at a unit linear distance are made longer by providing the wavy sections 7, the flowing of heat in such a pattern as a solid pattern having a high heat radiating effect is further suppressed. It has been proven that no detect occurs at the time of soldering the slightly thicker terminal C for connecting the pattern 9 and solid pattern connecting terminals A and B from measured soldering temperatures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit board formed by forming a conductive metal circuit pattern on an insulating substrate.

[0002]

2. Description of the Related Art A circuit board formed by forming a conductive metal circuit pattern on an insulating substrate has input terminals and output terminals, through which other components such as a power supply device and a volume, or a flexible device. Printed Ci
Although it is connected to other circuit boards such as Rcuit (hereinafter referred to as FPC), in general, input terminals and output terminals, particularly terminal portions connected to power supply patterns and GND patterns, have an area per unit length. Are printed larger than other circuit patterns.

[0003]

The terminal portion of the circuit pattern configured as described above has a large heat capacity, and an extremely high amount of heat is required for the solder to be brought into good contact with the terminal portion. In general, when soldering multiple locations such as thermocompression bonding using a planar heater or reflow soldering, set the amount of heat at the time of soldering according to the circuit pattern where the temperature rise is small. ,
In the case of joining a pattern such as an FPC, the cover film made of polyimide may be scorched, the FPC terminal may be peeled off, or the like, and a general printed wire may be used.
Even in the case of ing Board (hereinafter referred to as PWB), the terminal having a small heat capacity often peels off. Even in hand soldering, when connecting a cable having a small heat capacity to a terminal having a large heat capacity, or connecting other parts. At the time of connection, there is a problem that the coating or the resin exterior member is melted before the solder is melted on the terminal, and especially in electronic parts, there is a problem that a defect due to excessive heating may occur.

The present invention has been made in view of the above circumstances, and has as its object to provide a circuit board capable of reducing the heat capacity of a terminal portion of a circuit pattern.

[0005]

According to a first aspect of the present invention, there is provided a circuit board comprising a conductive metal circuit pattern formed on an insulating substrate. A constricted portion for suppressing mutual heat conduction is provided between the terminal portion and a wiring portion connected to the terminal portion. A corrugated portion may be provided on a part or all of the constricted portion.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a circuit board according to an embodiment of the present invention. FIG. 1 shows patterns 8, 9, 1 of main wiring portions 5 formed on a general circuit board.
0 are formed on the insulating substrate 1 and connected to the respective terminal portions 4 (hereinafter referred to as terminals A, B, C, and D).
Is provided. The terminals A and B are connected to a wide pattern 8 widely used for a power supply pattern or a GND pattern, which is generally called a solid pattern, and the terminal C is usually a shield for enclosing and isolating each power supply pattern or circuit type. The terminal D is connected to a slightly thicker pattern 9 used as a pattern, and the terminal D is connected to a thinner pattern 10 used as a very common signal line.

In general, the temperature of the pattern to which the terminals A and B are connected hardly rises, and the solder hardly melts on the surface thereof. However, the temperature of the pattern 10 connected to the terminal D rises quickly and Good melting. That is, in a normal circuit pattern configuration in which each terminal is simply connected to a pattern, it is impossible to perform the same amount of solder bonding within the same time with the same amount of heat.

Therefore, in this circuit board 3, the terminals A, B, and C have the same shape and size as the terminals, and the terminals A, B, and C are located between the terminals and the wiring portions 5 to which the terminals are connected. In order to suppress heat conduction from the terminal C to the pattern 9, a constricted portion 6 is provided, and in the terminals A and B, the constricted portion 6 is formed into a wave-like portion 7 which is bent many times. The difference in solder junction temperature between the terminal D connected to the pattern 10 having a small heat capacity and requiring no soldering was examined.

By providing the constricted portion 6 as described above, the width of the heat conduction path for diffusing the amount of heat given to the terminal portion 4 is reduced, and as a result heat dissipation along the circuit pattern is suppressed. The temperature rise efficiency in the section 4 is increased. In addition, by providing the corrugated portion 7 to increase the length of the constricted portion 6 at a unit linear distance, for example, the flow of heat into a pattern having high heat dissipation efficiency such as a solid pattern is further suppressed, and the terminal is provided near the terminal portion 4. Pattern 1 leading to D
It is intended to obtain an environment close to zero.

As a result of measuring the solder junction temperature at each terminal, at the terminals A and B connected to the solid pattern,
There is a tendency for the soldering temperature to increase slightly,
Because the difference in soldering temperature of each terminal is relatively small,
Approximately the same soldering can be performed at substantially the same bonding temperature, and the soldering is improved before the failure at the time of solder connection due to the difference in the heat capacity of the circuit pattern occurs.

The above is the structure of the circuit pattern, which is the feature of the circuit board according to the present invention. This structure can be applied not only to a circuit pattern formed on the surface layer of a circuit board, but also to an inner layer pattern directly connected to a terminal portion in the case of a multilayer circuit board. High effect. The wavy portion 7 may have a curved wavy shape as shown in the figure, or may have a linear wavy shape. In the manufacturing method, an insulating substrate is appropriately selected, a circuit pattern is formed by etching a conductive metal foil, and a conventional method such as a press bonding method or a build-up method is used as a substrate laminating means. Good.

[0012]

As described above, the use of the circuit board according to the present invention improves the workability at the time of mounting components and assembling a product, and prevents the cover film from being scorched at the time of FPC bonding and the FPC terminals from being peeled off. Also, since there is no need to worry about the melting of the coating at the time of connecting the cable or the occurrence of component failure due to excessive heating, it contributes to the improvement of the quality of the circuit board and the electric equipment incorporating the same, and the temperature rise efficiency at the terminal section. The improvement makes it possible to reduce the average process time in the solder bonding process.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a circuit board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating board 2 Circuit pattern 3 Circuit board 4 Terminal part 5 Wiring part 6 Neck part 7 Wavy part

Claims (2)

[Claims] 1. A circuit board (3) comprising a conductive metal circuit pattern (2) formed on an insulating substrate (1).
A circuit board provided with a constricted portion (6) for suppressing mutual heat conduction between any terminal portion (4) in the circuit pattern (2) and a wiring portion (5) connected to the terminal portion (4). 2. The circuit board according to claim 1, wherein a corrugated portion (7) is provided on a part or all of the constricted portion (6).