JP2002216581A - Printed wiring board with metal dome - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board having a switch mechanism utilized in an electronic device and superior in durability. SOLUTION: In the device, a first electrode wiring part 20 which is formed on a base board 10 and provided with an arc shaped part 20a on the top of which a spring metal dome 40 is mounted, a second electrode wiring 30 that is guided inside the arc shaped part 20a of the first electrode wiring 20 and an insulated film layer 50 by which the part under the metal dome 40 on the second electrode wiring part 30 is covered are provided. In this case, the covered range by the insulated film layer 50 is extended to the arc shaped part 20a of the first electrode wiring 20 in the printed wiring board with the metal dome and the superior durability is obtained by extending the covered range of the insulated film layer 50 since the stress of the metal dome against the insulated film layer 50 is greatly decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board provided with a switch mechanism used in electronic equipment and the like.

[0002]

2. Description of the Related Art In an electronic device such as a key switch of a mobile phone or an operation switch of a microwave oven, a pair of electrode wiring portions are brought into close proximity to each other, and a spring-like metal dome is placed on one of them. When the metal dome is pressed, the metal dome is crushed and comes into contact with the other electrode to turn on and off the switch.

[0005] This switch mechanism is illustrated in FIGS. 5 to 6, in which a pair of electrode wiring portions 2, 2 are provided on a base substrate 1.
3 are close to each other. Then, the contact portion 3a of the other electrode wiring portion 3 is attached to the arc-shaped portion 2a of the one electrode wiring portion 2 with the separated portion 2a separated from the arc-shaped portion 2a.
b, and a metal dome 4 made of a spring-formed metal product is placed on the arc-shaped portion 2a. Further, for insulation, an insulating coating layer 5 is provided on a portion where the metal dome 4 is straddled on the other electrode wiring portion 3 guided into the arc-shaped portion 2.

With this structure, if the metal dome 4 is pressed (clicked), the dome metal is crushed and the electrode wiring portion 3 is crushed.
Is electrically connected (turned on) to the electrode wiring portion 2 on which the metal dome 4 is placed,
When the pressing is released, the metal dome 4 is restored by its spring property, and thus becomes non-conductive (off). At the time of this pressing operation, the edge portion 4a of the metal dome 4 is close to the electrode wiring portion 3 side, but is cut off by the insulating film layer 5, and the insulating state is ensured.

[0005]

In this structure, however, the insulating film layer 5 is formed from the edge portion 4a of the metal dome 4.
Because the upper surface side of the substrate is high, the edge portion 4a runs over the insulating film layer 5 every time the click is performed, and the following problem occurs.

(1) First, as the edge portion 4a of the metal dome 4 rides on, the edge portion 4a bites into the insulating film layer 5 usually made of a material such as epoxy resin with time, and the bite is caused by the electrode. When it reaches the wiring portion 3 side, a contact failure such as a short circuit between the electrode wiring portions 2 and 3 occurs.

(2) If the thickness of the insulating film layer 5 is increased to prevent the biting of the edge portion 4a, the step δ ₀ between the upper surface of the insulating film layer 5 and the edge portion 4a of the metal dome 4 increases. Therefore, when the metal dome 4 is clicked, a phenomenon that the spring property is lost and the metal dome 4 does not return smoothly, that is, a so-called cave inversion occurs.

(3) Even more disadvantageously, even before the biting by the edge portion 4a reaches the contact failure, shavings are generated on the insulating film layer 5 side by the friction of the edge portion 4a. Is the contact part 3 on the electrode wiring part 3 side
There is a possibility that a contact failure (poor conduction at the time of a click) may occur due to scattering or adhesion near a.

The present invention has been made in view of such a conventional situation. Basically, in order to fundamentally solve the problem of damage to the insulating film layer side due to the edge portion of the metal dome, this insulating material is used. The structure in which the abrasion resistance of the coating layer side is improved is such that damage to the insulating coating layer side due to the edge portion of the metal dome is prevented as much as possible.

[0010]

According to a first aspect of the present invention, there is provided a first electrode wiring portion having an arc-shaped portion formed on a base substrate and having a springy metal dome mounted thereon. A second electrode wiring portion guided into the arc-shaped portion of the first electrode wiring portion, and an insulating film layer covering a portion where the metal dome straddles on the second electrode wiring portion, The printed wiring board with a metal dome is characterized in that a covering region of the insulating film layer is extended to an arc-shaped portion side of the first electrode wiring portion.

According to a second aspect of the present invention, there is provided a first electrode wiring portion having an arc-shaped portion formed on a base substrate and having a resilient metal dome mounted thereon, and the first electrode wiring portion. A second electrode wiring portion guided into the arc-shaped portion of the portion,
A metal dome comprising an insulating film layer covering a portion where the metal dome straddles on the second electrode wiring portion, and a wear-resistant layer formed on the insulating film layer. It is on the printed wiring board.

The present invention according to claim 3 is the printed wiring board with a metal dome according to claim 2, wherein the wear-resistant layer is a metal layer.

[0013]

1 and 2 show an embodiment of a printed wiring board with a metal dome according to the present invention. The basic structure of the printed wiring board is substantially the same as that of the wiring board shown in FIGS. However, the insulating film layer 50 is connected to the other electrode wiring portion, that is, the second electrode wiring portion.
Not only the electrode wiring section 30 but also one of the electrode wiring sections,
That is, the first electrode wiring portion 20 is extended to the arc-shaped portion 20a side to enlarge the covering region (area). In the figure, 10
Is a base substrate, 20b is a separated portion of the arc-shaped portion 20a,
Reference numeral 30a denotes a contact portion of the second electrode wiring portion 30, reference numeral 40 denotes a springy metal dome, and reference numeral 40a denotes an edge portion thereof.

Although the insulating film layer 50 is usually made of epoxy resin or the like, it is pressed by the edge portion 40a every time the metal dome 40 is clicked, as described above. In the present invention, the covering region of the insulating film layer 50 is greatly extended to the first electrode wiring portion 20 side as described above, although this eventually leads to a contact failure.

Therefore, the contact area of the metal dome 40 on the side of the insulating coating layer 50 with the edge portion 40a is greatly increased. That is, the insulating film layer 50 formed by the edge portion 40a
The stress per unit area is greatly reduced. As a result, the abrasion resistance of the insulating coating layer 50 is improved, and it takes a long time until a short circuit occurs, and a large improvement in durability can be obtained. Of course, the generation of shavings on the insulating film layer 50 side is greatly suppressed due to the reduction of the biting action of the edge portion 40a and the like, so that poor contact with the second electrode wiring portion 30 due to the shavings is also reduced. Can be done.

In the present invention, since only the area covered by the insulating coating layer 50 needs to be simply expanded, no special process is required, and it is possible to provide the same as the conventional method and to provide an inexpensive method.
In addition, the insulating film layer 50 can reduce the thickness of the metal dome 40 by reducing the biting action of the edge portion 40a, etc., by the extent that the covering area is expanded. As a result, when the thickness of the insulating film layer 50 is reduced, the first electrode wiring portion 20 (more precisely, the arc-shaped portion 2
Since the level difference [delta] ₁ and 0a) is small, good circulation is obtained that stress from the edge portion 40a of the metal dome 40 is correspondingly reduced.

FIG. 3 shows another embodiment of a printed wiring board with a metal dome according to the present invention. The basic structure of the printed wiring board is substantially the same as that of the wiring board shown in FIGS. An abrasion-resistant layer 60 made of a metal layer or the like is further coated on 50 by a printing method, a plating method, or the like. In addition,
In the figure, 10 is a base substrate, 20 is a first electrode wiring section, 20
a is an arc-shaped portion of the first electrode wiring portion 20, 20b is a separated portion of the arc-shaped portion 20a, 30 is a second electrode wiring portion, 30a
Denotes a contact portion of the second electrode wiring portion 30, 40 denotes a metal dome having a spring property, and 40a denotes an edge portion thereof.

Since the abrasion-resistant layer 60 is made of, for example, a metal layer, high abrasion resistance is obtained for the edge portion 40a of the metal dome 40. That is, the insulating film layer 50 is protected by the wear-resistant layer 60. As a result, the abrasion-resistant layer 60 is formed before the electrodes are short-circuited due to friction, biting, shaving, or the like due to the edge portion 40a of the metal dome 40.
Is damaged, the insulating coating layer 50 is further damaged, and a short circuit occurs. For this reason, more time is required until a short circuit occurs, and more excellent durability can be obtained. Further, in the wear-resistant layer 60, since the generation of shavings and the like is minimized by the metal material, the poor contact with the second electrode wiring portion 30 side due to the shavings is significantly reduced. Can be.

Also in the structure in which the wear-resistant layer 60 is provided, the presence of the wear-resistant layer 60 causes the insulating film layer 50 to be formed.
Can be made thinner. For this reason, the good circulation that the stress from the edge portion 40 a of the metal dome 40 is reduced by reducing the step δ ₂ from the first electrode wiring portion 20 is also obtained.

FIG. 4 shows another embodiment of a printed wiring board with a metal dome according to the present invention. The basic structure of the printed wiring board is substantially the same as that of the wiring board shown in FIGS. An abrasion resistant layer 60 made of a metal layer or the like is further coated on the expanded insulating film layer 50. With this structure,
Since the coverage area of the wear-resistant layer 60 is expanded together with the insulating coating layer 50, more excellent durability can be obtained.

The thickness of the insulating coating layer 50 can be made thinner by the expanded coating of the wear-resistant layer 60. For this reason, the step δ ₁ from the first electrode wiring portion 20 can be made smaller, and the metal dome 40
The good circulation that the stress from the edge portion 40a is reduced.

Incidentally, as a printed wiring board with a metal dome according to the present invention having the structure shown in FIGS.
u) After forming the first electrode wiring portion 20 and the second electrode wiring portion 30 each having a thickness of 35 μm, the insulating film layer 50 is extended to the arc-shaped portion 20a side of the first electrode wiring portion 20 to cover the first electrode wiring portion 20. The dome 40 was set, and ten sample printed wiring boards were manufactured. At this time, the wiring width of the first electrode wiring section 20 and the second electrode wiring section 30 is 0.3 mm, and the interval (gap) between the first electrode wiring section 20 and the second electrode wiring section 30 is 0.9.
mm, the coating area width of the insulating coating layer 50 was 1.2 mm, and the thickness of the insulating coating layer 50 was 10 μm. Repeated clicks (keying test) of the metal dome 40 were performed on each sample, and the average number of keying operations before contact failure due to damage to the insulating coating layer 50 was determined. The number of keying operations was 180,000 or more. there were.

A printed wiring board with a metal dome according to the present invention having a structure shown in FIG. 4 has a conductor (Cu) thickness of 35.
After forming the first electrode wiring portion 20 and the second electrode wiring portion 30 of μm, the insulating film layer 50 is extended to the side of the arc-shaped portion 20a of the first electrode wiring portion 20 to cover the same. An abrasion-resistant layer 60 made of a metal layer was coated thereon by a plating method, and a metal dome 40 was provided to manufacture ten sample printed wiring boards. At this time, the wiring width of the first electrode wiring section 20 and the second electrode wiring section 30 is 0.3 mm,
The distance (gap) between the first electrode wiring section 20 and the second electrode wiring section 30 is 0.9 mm, and the width of the covering region of the insulating coating layer 50 is 1.
2 mm, the thickness of the insulating film layer 50 is 10 μm, and the wear-resistant layer 6
0 had a thickness of 1.0 μm. For each sample,
The metal dome 40 was repeatedly clicked (keying test), and the average number of keying operations before contact failure due to damage to the insulating coating layer 50 was determined.
It was more than ten thousand times.

On the other hand, after forming one electrode wiring portion 2 and the other electrode wiring portion 3 having a conductor (Cu) thickness of 35 μm as a printed wiring board with a metal dome having a conventional structure shown in FIGS. Then, the insulating film layer 5 was coated on the other electrode wiring portion 3 and a metal dome 40 was provided, thereby manufacturing ten sample printed wiring boards. At this time, the wiring width of one electrode wiring part 2 and the other electrode wiring part 3 is 0.3 mm,
The distance (gap) between one electrode wiring portion 2 and the other electrode wiring portion 3 is 0.9 mm, and the width of the covering area of the insulating coating layer 5 is 0.3 mm.
mm, and the thickness of the insulating coating layer 5 was 10 μm. The metal dome 40 was repeatedly clicked (keying test) on each sample, and the average number of times of keying until a contact failure occurred due to damage to the insulating coating layer 5 was obtained. The number of times of keying was about 100,000. there were.

[0025]

As is apparent from the above description, according to the printed wiring board with the metal dome of the present invention, the area covered by the insulating film layer can be enlarged, or the abrasion-resistant layer can be further provided on this layer to provide an insulating layer. Even if the metal dome is clicked frequently, the stress on the insulating coating layer side can be greatly reduced even if the metal dome is clicked frequently, and the durability is greatly improved. Significant improvement is obtained. In addition, since the generation of shavings due to friction between the edge of the metal dome and the insulating coating layer side is effectively suppressed,
It is possible to significantly reduce poor contact.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a printed wiring board with a metal dome according to the present invention.

FIG. 2 is a plan view of the printed wiring board with a metal dome of FIG. 1;

FIG. 3 is a longitudinal sectional view showing another example of a printed wiring board with a metal dome according to the present invention.

FIG. 4 is a longitudinal sectional view showing another example of a printed wiring board with a metal dome according to the present invention.

FIG. 5 is a longitudinal sectional view showing a printed wiring board with a metal dome having a conventional structure.

6 is a plan view of the printed wiring board with a metal dome of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Base board 20 1st electrode wiring part 20a Arc-shaped part 20b Separation part 30 2nd electrode wiring part 40 Spring metal dome 40a Edge part 50 Insulation film layer 60 Abrasion resistant layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E338 AA01 BB63 CD17 CD40 EE11 EE21 5G006 AA01 AB25 AZ01 BA01 BA02 BB03 FB04 5G051 AC20 AC30

Claims (3)

[Claims] A first electrode wiring portion formed on a base substrate and having an arc-shaped portion on which a resilient metal dome is placed; and a first electrode wiring portion provided in the arc-shaped portion of the first electrode wiring portion. A second electrode wiring portion provided on the second electrode wiring portion, and an insulating film layer covering a portion where the metal dome straddles the second electrode wiring portion. A printed wiring board with a metal dome, which is extended to the arc-shaped portion side of the printed wiring board. 2. A first electrode wiring portion formed on a base substrate and having an arc-shaped portion on which a spring-like metal dome is mounted, and a first electrode wiring portion provided in the arc-shaped portion of the first electrode wiring portion. A second electrode wiring portion provided on the second electrode wiring portion, and an insulating film layer covering a portion where the metal dome straddles on the second electrode wiring portion. A wear-resistant layer is formed on the insulating film layer. A printed wiring board with a metal dome. 3. The printed wiring board with a metal dome according to claim 2, wherein the wear-resistant layer is a metal layer.