JPS6286894A - Printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to conductors for printed wiring boards with improved solderability.

BACKGROUND OF THE INVENTION In recent years, printed wiring boards have become denser, and various soldering methods have been used to accommodate the higher density.

A conventional printed wiring board will be explained below.

FIG. 5 is a plan view showing a conductor pattern when a conventional component terminal and a conductor of a printed wiring board are soldered, in which 1 is the terminal of the component to be soldered, 2 is the conductor part of the printed wiring board, and 3 1 is a through-N hole portion, and a shaded portion A is a portion where the terminal 1 of the component and the conductor portion 2 of the printed wiring board are soldered.

Conventionally, when soldering nine component terminals 1 of a printed wiring board, a method is generally used in which heat is applied to the component terminal 1 and the conductor portion 2 and soldering is performed, and electrical connection is made at the shaded area A. . Note that in order to make this electrical connection, a conductor pattern on a printed wiring board is used. Furthermore, in soldering, a certain amount of heat is determined in order to obtain normal solderability, and if there is variation in the amount of heat, the solderability will be affected.

Problems to be Solved by the Invention However, in the above conventional configuration, the conductor portions other than the shaded area A, which is the soldered portion, are 2" + 2)), 2C
(hereinafter referred to as connection conductor), the area of the connection conductor differs depending on each conductor portion 2.

Therefore, the amount of heat dissipated differs depending on the connected conductor, resulting in variations in solderability and poor soldering.

In addition, the connecting conductor is straight, and when high-density mounting,
Since the length could not be long, heat radiation from the connecting conductor increased, and a large amount of heat was required, resulting in an increase in thermal stress on the printed wiring board and, furthermore, an increase in equipment costs.〇 The present invention solves the above-mentioned problems, and aims to provide a printed wiring board that can reduce the amount of heat dissipated from the connecting conductors and has stable solderability.

Means for Solving the Problems In order to achieve this object, the printed wiring board of the present invention has a structure in which the thermal resistance of the connecting conductor portion connected to the soldered portion is greater than that of the soldered portion.

Effect: This configuration increases the thermal resistance of the connecting conductor.
It reduces heat radiation from the connecting conductors and allows stable soldering.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings. FIG. 1 shows a plan view of essential parts of a printed wiring board in a first embodiment of the present invention. In Figure 1,
1 and 3 are component terminals and through-hole portions, respectively, similar to the conventional example. The shaded area 4 is the soldering area between the conductor of the printed wiring board and the component terminal, and each soldering area is configured to have the same area.

Reference numeral 5 denotes a connecting conductor portion connected to the soldering portion 4.

The operation of the printed wiring board configured as above will be described below.

FIG. 2 is a characteristic diagram showing the relationship between the width of the connecting conductor portion 5 and the amount of heat radiated from the connecting conductor portion 6 and the through-hole portion 3. As shown in FIG.

From FIG. 2, when the length of the connecting conductor part 6 is constant, the smaller the width of the connecting conductor part 5 is compared to the width of the soldering part 4, the smaller the amount of heat radiation. That is, as the width of the connecting conductor portion 5 becomes smaller than the width W of the soldering portion, the amount of heat dissipation decreases to a certain extent, and thereafter becomes approximately constant.

Further, FIG. 3 is a characteristic diagram showing the relationship between the length of the connecting conductor part 5 and the amount of heat radiated by the connecting conductor part 5 and the through-hole part 3, with the width of the connecting conductor part 50 being constant. From FIG. 3, the longer the length of the connecting conductor portion 5, the smaller the amount of heat radiation.

That is, as the distance from the soldering part 4 to the through-hole part 3''! increases and the length L of the soldering part is exceeded, the amount of heat radiation decreases to a certain extent, and thereafter the amount of heat radiation becomes constant.

As described above, according to the first embodiment, when the connecting conductor part 5 is bent, the width is made small, and the length is set as long as shown in FIG. 1, the thermal resistance of the connecting conductor part 6 increases. Since the amount of heat radiated from the soldered portion 4 accounts for most of the total amount of heat radiated, the amount of heat radiated from portions other than the soldered portion 4, such as the connection conductor portion 5, can be made extremely small. Furthermore, since the areas of the soldering portions 4 are equal, variations in solderability among the conductors can be suppressed.

Next, a second embodiment of the present invention will be described.

FIG. 4 is a plan view of the main parts of the printed wiring board in the second embodiment, and the configuration of the second embodiment is the same as that of the first embodiment.

The through holes 3 are arranged in a grid at regular intervals on a printed wiring board conductor pattern inspection machine. Therefore, as shown in FIG. 4, unnecessary heat radiation can be eliminated by freely determining the bending method of each connecting conductor portion 5 and the setting of the position where it is connected to the through-hole portion 3.

Note that the same effect as described above can also be obtained by reducing the thickness of the connecting conductor portion 5. In this case, only the connecting conductor portion 5 is not plated, or the number of times of plating is reduced to reduce the thickness. Furthermore, in the case of a multilayer board, the connecting conductor portion 6 may be made longer, smaller in width, and thinner by using layers other than the layers to be soldered. In any case, the method of connecting the soldered part and other conductor land parts (for example, through-hole parts) via the connecting conductor depends on the soldering method and land shape, so that the thermal resistance of the connecting conductor is higher than that of the soldered part. You can set it so that it becomes larger.

Effects of the Invention In the present invention, by setting the thermal resistance of the connecting conductor to be greater than that of the soldered portion, it is possible to extremely reduce heat radiation from areas other than the soldered portion, thereby reducing the amount of heat required for soldering. Moreover, it has the excellent effect of stabilizing solderability.

[Brief explanation of drawings]

Fig. 1 is a plan view of the main parts of a printed wiring board according to the first embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between the width of the connecting conductor and the amount of heat dissipation, and Fig. 3 is a diagram showing the relationship between the length of the connecting conductor and the amount of heat dissipation. A characteristic diagram showing the relationship, FIG. 4 is a plan view of the main part showing the second embodiment, and FIG. 6 is a plan view of the main part of a conventional printed wiring board. 1...Component terminal, 3...Through hole part, 4...Soldering part, 6...Connecting conductor part. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
- Figure 2: Width of the conductor (conductor width) Figure 4: Figure 4

Claims (2)

[Claims] (1) A soldering part where a component terminal is soldered to a conductor, a connecting conductor part connected to the soldering part and having a higher thermal resistance than the soldering part, and a through hole etc. connected to the connecting conductor part. A printed wiring board comprising a conductive land portion. (2) The printed wiring board according to claim (1), wherein the connecting conductor portion is bent and connected to an arbitrary position of the through-hole portion.