JPH1174626A - Printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed board wherein a gap pattern which sufficiently discharge a lightning surge at a power source circuit of a wired telephone set. SOLUTION: Solder parts 2 and 4 wherein crest parts 2a and 4a and trough parts 2b and 4b, in saw-tooth shape, are provided at ends of patterns 1 and 3 are fused by a re-flow soldering method with a cream solder, while the solder parts 2 and 4 faced each other with a predetermined spacing, and an insulating material is so coated as to cover at least a part of the saw-tooth shape, on the upper surface of the patterns 1 and 3 and the solder parts 2 and 4, thus a gap pattern is formed. This is applied to a power source circuit of a wired telephone set to prevent malfunction of a circuit or breakdown of a semiconductor element caused by lightning surge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board, and more particularly, to a printed circuit board on which a discharge pattern for discharging a lightning surge generated in, for example, a power supply circuit of a wired telephone is formed.

[0002]

2. Description of the Related Art Electronic equipment is provided with various preventive means for preventing a circuit from being damaged when a sudden transient voltage (surge voltage) is applied due to lightning, arc grounding or static electricity. ing. As one of the prevention means, for example, there is a method using a component such as a surge absorber, but without using such a component, a discharge pattern such as a gap pattern or a through hole is formed, and static electricity or the like is generated only between the patterns. A printed circuit board has been developed which discharges and protects the mounted components from being destroyed.

[0003] Here, the printed circuit board on which the discharge pattern is formed by the through holes has a conductor in the through holes connected to a pattern in which a surge voltage is generated.
The conductor of the through hole is also connected to the adjacent ground pattern. A printed circuit board that discharges static electricity and the like only between adjacent two through-holes and protects mounted components and the like is described in, for example, Japanese Patent Application Laid-Open No. 7-79052.

FIG. 3 is a perspective view showing a main part of a conventional printed circuit board on which a discharge pattern formed by through holes is formed. As shown in FIG. 3, a pattern 14 connected to an input line such as a power supply input line is formed on the printed circuit board 10, and is connected to a through hole 14a. The printed circuit board 10 has a pattern 1 applied as a ground.
2 are formed and connected to the through holes 12a. The through holes 12a and 14a are close to each other, and the surface thereof is covered with a conductor. In such a printed circuit board 10, when a surge voltage exceeding a predetermined value is applied to the pattern 14, the charge is transferred to the through hole 14.
a flows into the through hole 12a and discharges.

Thus, the through holes 12a, 14a
By forming the electronic component, the electronic components mounted on the printed circuit board 10 are protected, and the through holes 12a and 14a themselves do not require a large space on the substrate surface, so that the substrate can be downsized.

However, in the case of a printed circuit board provided with such a discharge pattern formed by through holes, there is a disadvantage that a step of forming through holes is required. For this reason, for example, JP-A-4-22086 or JP-A-5-67851 discloses a conventional technique of a printed circuit board for forming a gap pattern for discharging static electricity only by a pattern.

FIG. 4 is a schematic view showing a main part of a conventional printed circuit board on which a discharge pattern based on a gap pattern is formed. As shown in FIG. 4, a conventional printed circuit board 20 having a gap pattern has patterns 22 and 24 formed on the upper surface of the printed circuit board 20 by a photographic method. Further, the patterns 22 and 2 on the printed board 20 are
Solder portions 22a and 24a are formed at the ends facing 4 and a plurality of peaks and valleys are formed at the tips of the solder portions 22a and 24a in a saw blade shape.

FIGS. 5 and 6 are enlarged perspective views of a portion D surrounded by a dotted circle in FIG. 4, respectively. That is, FIG. 5 is a perspective view showing a gap pattern in which the solder portion is formed wider, and FIG. 6 is a perspective view showing a gap pattern in which the solder portion is formed narrower from the peak to the valley.

As shown in FIG. 5, in a gap pattern in which the solder portion is widened, patterns 22 and 24 are formed on a substrate by a photographic method so as to oppose each other. It has been applied. Also,
Solder portions 22a-1 and 24 each having a plurality of peaks and valleys formed in a saw blade shape at the ends of the opposing patterns 22 and 24.
a-1 is provided.

The solder portions 22a-1 and 24a-1 are not coated with a resist, but are formed by fusing solder to the patterns 22, 24 by, for example, a reflow soldering method using cream solder. These solder portions 22a-1, 24a-
Reference numeral 1 denotes a peak and a valley formed in a saw blade shape between the opposing patterns 22 and 24, and a portion further extending in the pattern direction from the valley is exposed to the outside.

The gap pattern formed as described above is applied to a printed circuit board used in electronic equipment and the like as described in Japanese Patent Application Laid-Open No. 5-67851. If lightning or static electricity occurs,
Since the gap pattern discharges and is grounded, the semiconductor element in the circuit is not destroyed. In addition, since they are not physically connected, the whole earth balance does not go out of order. Therefore, there is no adverse effect on beat measures.

Similarly, in the gap pattern shown in FIG. 6 in which the solder portion is formed from the peak portion to the valley portion, patterns 22 and 24 are formed on a substrate by a photographic method, and a resist 2 is formed on this surface.
6 is applied. Further, solder portions 22a-2 and 24a-2 having a plurality of peaks and valleys in a saw blade shape are provided at the ends where the patterns 22 and 24 face each other. The resist 26 is not applied to the solder portions 22a-2 and 24a-2, and is formed by fusing solder by, for example, a reflow soldering method using cream solder. in this way,
The solder portions 22a-2 and 24a-2 are
The narrow gap pattern is formed by the valley located at the end of the valley and the ridge extending and protruding from the valley.

This kind of gap pattern is disclosed in
As described in Japanese Patent No. 22086, the circuit is provided to protect the circuit from being damaged by a surge voltage applied between the input side and the output side of the line filter. This eliminates the need for a protective component such as a surge killer, thereby reducing costs and reducing the size of the power supply device.

[0014]

However, the conventional printed circuit board on which a discharge pattern such as a gap pattern or a through hole is formed has a problem that it does not have a sufficient discharge capability against a lightning surge. In particular, when the above-described conventional technique is applied to a power supply circuit in a wired telephone, a remarkable discharge effect cannot be obtained, and a semiconductor element in the circuit may be broken. In addition, the printed circuit board on which the gap pattern is formed has a shape of the gap pattern,
That is, a remarkable difference occurs in the discharge effect depending on the angle of the sharp edge portion of the saw blade shape, the area of the exposed solder portion, and the like. However, a specific limitation on such a shape has not been made. The present invention solves such a conventional problem by providing a printed circuit board provided with a gap pattern capable of sufficiently discharging a lightning surge in a power supply circuit of a wire telephone, for example, and providing a remarkable discharge effect. The purpose is to do.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a first pattern in which a peak and a valley having a saw blade shape are provided at an end, and a predetermined interval between the first pattern and the first pattern. A second pattern serving as a discharge path of a first pattern having opposing saw blade-shaped peaks and valleys at its ends, and an insulating material applied to the first pattern and the second pattern. Then, the insulating material is applied so as to cover at least a part of the saw blade shape. Here, the insulating material is a resist, which is applied so as to cover a peak of about 0.1 mm from a valley of a saw blade shape,
The angle θ of the peaks formed in the first pattern and the second pattern is set to 45 ° ≦ θ <90 °, and the peaks and valleys of the saw blade formed at the ends of the first pattern and the second pattern are formed. The part is formed by fusing a conductive material by a reflow soldering method using cream solder, and this printed circuit board is applied to a power supply circuit of a wired telephone.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a plan view showing an embodiment of a printed board according to the present invention, and FIG. 2 is a perspective view of the printed board shown in FIG. The printed circuit board according to the present embodiment is applied to, for example, a power supply circuit of a wired telephone, and is a printed circuit board on which a surge pattern is applied by a lightning strike or static electricity to prevent a circuit from being damaged. FIGS. 1 and 2 show only the discharge pattern portion, that is, the gap pattern. The pattern 1 side is connected to a power supply circuit portion, and the pattern 3 side is connected to an earth pattern or the like so as to be a discharge path. .

The patterns 1 and 3 are patterns formed on the upper surface of the printed circuit board by a photographic method, and have predetermined intervals and are located such that their ends face each other. Also,
Solder portions 2 and 4 are formed at the opposite ends. The solder portions 2 and 4 are formed by fusing solder to the patterns 1 and 3 by a reflow soldering method using cream solder, for example. As shown in FIG. 1, the solder portions 2 and 4 extend from the ends of the patterns 1 and 3 to the valleys 2b and 4b, and the sharp ridges extending further from the valleys 2b and 4b and projecting. 2a and 4a. The peaks 2a and 4a are provided at three places on the solder part 2 and three places on the solder part 4, respectively, and are formed in a saw blade shape.

Here, an example of a specific shape of the solder portions 2 and 4 will be described using a triangle C shown by a dotted line in FIG. The triangle C is a virtual triangle drawn virtually when explaining the shape of the solder portions 2 and 4, and such a virtual triangle C is not formed in the solder portions 2 and 4. By assuming the virtual triangle C, no error occurs in each dimension value, and the specific shape of the solder portions 2 and 4 can be accurately shown.

As shown in FIG. 1, the virtual triangle C is an isosceles triangle having a base X1 and a height Y1. The base X1 of the virtual triangle C is located at a distance Y3 from the valleys 2b and 4b. Such a virtual triangle C is divided into a portion from the valleys 2b and 4b to the base X1 and a tip which is a ridge protruding from the valley. That is, the tip part which is a part of the virtual triangle C has the shape of the peaks 2a and 4a formed on the solder parts 2 and 4.

In this embodiment, the interval Y3 is 0.5 mm, the base X1 is 1 mm, and the height Y1 is 1 m.
m. Also, the ridges 2a, 4a thus formed
Is 53 °, and according to some experimental results, preferably, the angle θ is 45 ° ≦ θ <90.
° turned out to be good.

As shown in FIG. 1, in the solder portions 2 and 4,
Three virtual triangles C are arranged at a predetermined interval X2. The imaginary triangles C arranged in this manner have the tips of the peaks 2a and 4a as described above. Therefore, the solder portions 2 and 4 are provided with three peak portions 2a and 4a, and are formed in a saw blade shape. Here, the interval X2 is 0.5 mm.

As shown in FIG. 2, a resist 5 made of an insulating material is applied to the upper surfaces of the patterns 1 and 3 and the solder portions 2 and 4. This resist 5 first has a pattern 1
3 and the solder portions 2 and 4 are applied over the entire surface. As shown in FIG. 1, the peaks 2a and 4a remove the resist applied to the portions A and B (hatched portions) in order to perform discharge during this period. The parts A and B correspond to the valleys 2b, 4b
From the valleys 2b, 4b to the position of the width Y5. In other words, the resist 5 applied to the patterns 1 and 3 and the solder portions 2 and 4 has the valley portions 2b and
4b to the position of the interval Y4. here,
The distance Y4 from the valley is 0.1 mm, and the width Y5 is 0.5.
mm. In this manner, the resist is removed from the portions A and B shown in FIG. 1, and a part of the ridges 2a and 4a, which are conductors, is exposed, so that discharge is efficiently performed. Here, the interval Y2 between the part A and the part B shown in FIG.
m.

Next, the operation of the embodiment of the printed circuit board according to the present invention will be described in detail. In the printed circuit board according to the present embodiment, when a lightning surge or the like occurs, the surge voltage is discharged by the gap patterns shown in FIGS. 1 and 2 to prevent the semiconductor elements of the circuit from being destroyed. Here, a lightning surge caused by a lightning strike has a characteristic of escaping to a low impedance pattern or a narrow gap formed in a power supply circuit or the like. In the present embodiment, as shown in FIG.
A low impedance is realized by removing a part of the resist of the A portion and the B portion applied to the portion 4. The solder portions 2 and 4 formed on the patterns 1 and 3 have sharp peaks 2.
Since a and 4a are formed and the leading end portions thereof are opposed to each other to form a narrow gap pattern, lightning strikes and the like can easily escape.

In the printed circuit board formed as described above, for example, when a lightning surge due to lightning strike occurs on the pattern 1 side, the peak 2a of the solder 2 formed on the pattern 1 is changed to the solder 4 formed on the pattern 3. Discharge is started toward the ridge 4a. Therefore, by connecting the pattern 3 side to the ground, the lightning surge generated in the pattern 1 escapes to the ground side (and vice versa). Therefore, it is possible to prevent the power supply circuit connected to the pattern 1 from being broken.

Next, experimental results of the printed circuit board according to the present embodiment will be described.

[0026]

[Table 1]

Under the conditions shown in Table 1, a high impulse voltage (15 kV) was applied between the commercial power supply and the telephone line. Under these conditions, the gap pattern used in the experiment includes a conventional printed circuit board shown in FIG. 5 where the solder portion is widely exposed, and a gap pattern exposed partly as shown in FIG. The following printed circuit board was used.

In the conventional printed circuit board shown in FIG. 5 in which the solder portion is widely exposed, when an impulse voltage is applied, a sufficient discharge effect cannot be obtained (the pattern portion does not change after the experiment), and the mounted component is destroyed. Results. In such a gap pattern in which discharge is not performed, a surge component (surge absorber or the like) is separately required.

On the other hand, as shown in FIG. 2, in the printed circuit board in which the gap pattern is partially exposed and the tip is formed at an acute angle (45 ° or less), the copper foil portion of the exposed pattern is partially Although it flew off, it was reliably discharged by the saw blade-shaped gap pattern, and there was no effect on other mounted components.

Further, the durability of the copper foil portions was compared when the discharge was performed while changing the angle of the acute angle portion of the gap pattern. At this time, the condition of the solder portion as shown in FIG. 2 (dischargeable condition)
Below, the case where the angle of the acute angle part was set to 30 ° to 44 ° and the case where the angle was set to 90 ° were compared. The acute angle is 3
In the case of 0 ° to 44 °, when the impulse voltage was applied, a part of the exposed copper foil portion of the gap pattern was skipped, and the portion was further burnt.

On the other hand, when the angle of the acute angle portion is 90 °, there is no change in the exposed gap pattern. However, since the discharge effect is not sufficient in this state, it is necessary to add a limiting resistor. As described above, the sharp protrusion of the solder portion is formed at an obtuse angle (90 °).
In the case of (above), the discharge efficiency is reduced as compared with the acute angle and a sufficient discharge cannot be obtained. However, the problem can be solved by adding a limiting resistor. If an angle that enhances the surge effect as a power supply circuit is selected in consideration of such strength at the time of discharge, etc., the angle θ becomes
It has been found that the angle is preferably 45 ° or more and less than 90 ° (45 ° ≦ θ <90 °), and most preferably about 53 °.

Although the embodiments of the printed circuit board according to the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and can be changed without departing from the gist of the present invention. . For example, in the virtual triangle C shown in FIG. 1, the arrangement interval X2 is 0.5 mm, and the interval Y2 between the portion A and the portion B is 0.4 mm, but the invention is not limited thereto. Further, the number of peaks formed on the solder portion is not limited to three, and a plurality of peaks may be formed.

[0033]

As described above, according to the printed circuit board of the present invention, a remarkable discharging effect can be obtained, and a circuit design having a high degree of freedom can be realized because a tall component such as a surge absorber is not required. Further, since the lightning surge countermeasures can be realized only with the pattern formed on the upper surface of the printed circuit board, the cost is reduced. Furthermore, by defining the shape of the gap pattern, that is, the angle of the sharp part of the saw blade, the area of the exposed solder part, and the like, it is possible to form a gap pattern having a high discharge effect.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a printed circuit board according to the present invention.

FIG. 2 is a perspective view of the printed circuit board shown in FIG.

FIG. 3 is a perspective view showing a main part of a conventional printed circuit board on which a discharge pattern formed by through holes is formed.

FIG. 4 is a perspective view showing a main part of a conventional printed circuit board on which a discharge pattern based on a gap pattern is formed.

FIG. 5 is a perspective view showing a gap pattern in which a solder portion is formed wider.

FIG. 6 is a perspective view showing a gap pattern in which a solder portion is formed narrow from a peak portion to a valley portion.

[Explanation of symbols]

 1 pattern 2 solder part 3 pattern 4 solder part 5 resist

Claims (4)

[Claims] 1. A first pattern having a saw blade-shaped peak and a valley at an end thereof, and a saw blade-shaped peak and a valley facing the first pattern at a predetermined interval. A second pattern provided at an end portion serving as a discharge path of the first pattern; and an insulating material applied to the first pattern and the second pattern, wherein the insulating material is at least part of the saw blade shape. A printed circuit board, which is coated so as to cover the printed circuit board. 2. The printed circuit board according to claim 1, wherein the insulating material is a resist, which is applied so as to cover a ridge of about 0.1 mm from the valley of the saw blade shape. Printed circuit board. 3. The printed circuit board according to claim 1, wherein the angle θ at the tip of the peak formed in the first pattern and the second pattern is 45 ° ≦ θ <90 °. Printed circuit board. 4. The printed circuit board according to claim 1, wherein said printed circuit board is applied to a power supply circuit of a wired telephone.