JPH069310B2 - Method of manufacturing through hole for flexible substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a through hole for a flexible substrate, which connects circuit patterns provided on both sides of a flexible substrate.

[Conventional technology]

Conventionally, a through-hole technique has been developed and put into practical use as a method for easily connecting circuit patterns provided on both surfaces of a substrate.

FIG. 4 is a side sectional view showing the structure of a conventional through hole of this kind.

As shown in the figure, in the conventional through hole, the circuit patterns 101 and 103 are formed on both surfaces of the substrate 100, the through hole 107 is formed, and the inside of the through hole 107 is filled with the conductive paint 105 made of silver paste. The conductor paint 105 has a structure in which the upper and lower circuit patterns 101 and 103 are electrically connected.

[Problems to be Solved by the Invention]

This type of conventional through hole is shown in Fig. 5 (No. 4).
As shown in the enlarged view of the portion A in the figure), the through hole 107
Between the edge portion 100a at the end of the
The layer constituted by 05 is interposed.

However, since this layer is only one layer, its strength is weak and cracks 105a and the like are likely to occur in the conductive coating material 105 due to heat and pressure. For this reason, there is a problem that the resistance value of the through hole portion increases and a conductive defect occurs.

In particular, when the substrate 100 is made of a flexible thin synthetic resin film (flexible substrate), the substrate 100 is easily bent, and thus the crack 105a is very likely to occur.

The present invention has been made in view of the above points, and provides a method for manufacturing a through-hole for a flexible substrate in which resistance value increase or conduction failure does not easily occur in the through-hole portion even if the substrate is formed of a flexible substrate. To do.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention provides a method of manufacturing a through hole for a flexible substrate, in which a pad made of a conductive thin film is formed only on one surface of a flexible substrate made of a synthetic resin film having flexibility. A step of forming a punch on the pad from the surface of the flexible substrate on which the pad is formed to form a through hole penetrating the pad and the flexible substrate; and a side of the flexible substrate on which the punch is inserted. The third step of filling the inside of the through-hole from the surface opposite to the surface of the above-mentioned through-hole to the position beyond the edge portions of both ends of the through-hole, and the conductive paint exposed on both sides of the flexible substrate. And a fourth step of printing a circuit pattern so as to cover the entire surface of each.

[Action]

With the above-described structure, since two layers of conductive material are respectively interposed between the edge portions at both ends of the through hole formed in the flexible substrate and the outside, it is possible to strengthen the portion and to prevent cracks or the like. Less likely to occur.

Also, the conductive paint that is piled up on the edge part on the side opposite to the side where the conductive paint is filled becomes smaller in amount, but since the conductive paint is connected to the pad provided on this surface side in advance, this The layer of the conductive coating material that is deposited on the edge portion becomes thick, and cracks and the like are less likely to occur from this point as well.

Further, since the punch is inserted from the side where the pad is provided, the edge portion of the through hole on the side where the punch is inserted and the end portion of the pad are gently inclined toward the inside to form an inclined surface. Since the amount of conductive paint is small, cracks and the like are less likely to occur.

Furthermore, the edge portion of the through hole on the side where the pad of the flexible substrate is not formed protrudes at an acute angle,
Since this edge portion is made of a synthetic resin having flexibility, it is low and not an acute angle, and is soft because it is a resin. In addition, the conductive paint deposited on this side is thick on the side where the conductive paint is filled, so that the layer is thick, and cracks and the like are unlikely to occur on this side as well.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side sectional view showing the production of a through hole produced by using the method for producing a through hole for a flexible substrate according to the present invention.

As shown in the figure, the through hole is provided with a through hole 2 in the flexible substrate 1, a pad 6 made of a conductive material is formed on one surface of the flexible substrate 1, and the through hole 2 is electrically conductive. The paint 3 is filled, and circuit patterns 4 and 5 are printed on the conductive paint 3 so as to cover the entire surfaces thereof.

Here, the flexible substrate 1 is made of, for example, a polyester film having flexibility.

The conductive paint 3 is made of a material such as silver paste. The conductive paint 3 is filled in the through hole 2 and further spreads over both surfaces of the flexible substrate 1, that is, over the edge portions 1a, 1a at both ends of the through hole 2. At this time, the conductive paint beyond the lower edge portion 1 a of the through hole 2 is filled up to the position where it is connected to the pad 6.

The circuit patterns 4 and 5 are made of, for example, a silver paste, and are screen-printed on the conductive paint 3 exposed on both surfaces of the substrate 1 so as to cover the entire surface of the conductive paint 3.

The pad 6 is formed on one surface of the flexible substrate 1 so as to surround the through hole 2. The pad 6 is made of a conductive paint such as silver paste.

FIG. 2 is a diagram showing a method of manufacturing this through hole.

As shown in FIG. 3A, first, the pad 6 is formed at a predetermined position on the flexible substrate 1. The pad 6 is baked by screen-printing a silver paste in a circular shape, for example.

Next, as shown in FIG. 1B, the punch 50 is projected from the side of the flexible substrate 1 on which the pad 6 is formed to form the through hole 2 in the flexible substrate 1.

FIG. 3 is an enlarged view showing a portion C of FIG. 2 (b) when the punch 50 is thrust into the flexible base 1.

As shown in FIG. 3A, when the punch 50 is inserted from the side of the pad 6, the end portion 6a of the pad 6 on the side of the through hole 2 and the edge portion 1a of the flexible substrate 1 are dragged into the punch 50 and the through hole is formed. I try to get a little inside 2.
Then, as shown in FIG. 3B, when the punch 50 is pulled out, the end portion 6a and the edge portion 1a of the pad 6 try to return in the pulling-out direction, but they do not return completely. As a result, finally, the inner peripheral side end 6a and the edge portion 1a of the pad 6 facing the through hole 2 do not form an acute angle but become an inclined surface slightly inclined to the inner side of the through hole 2.

Next, as shown in FIG. 2 (c), conductivity is introduced from the direction of the arrow D into the through hole 2 from which the punch 50 is pulled out (that is, from the surface opposite to the surface of the flexible substrate 1 on which the punch 50 is inserted). Fill with paint 3. This conductive paint 3 is through hole 2
Are filled up to a position beyond both edge portions 1a, 1a.

Then, as shown in FIG. 3D, circuit patterns 4 and 5 are screen-printed on both surfaces of the flexible substrate 1 so as to cover the entire surface of the conductive paint 3.

This completes this through hole.

As shown in FIG. 1, according to the through hole of the present invention, the edge portions 1a, 1 on both sides of the flexible substrate 1 are formed.
Since two layers, that is, the layer formed by the conductive paint 3 and the layer formed by the conductor pattern 4 (or 5) are provided between a and the outside, these portions are reinforced. Therefore, even if the flexible substrate 1 bends, cracks or the like are unlikely to occur in this portion.

By the way, in the case of the present invention, as shown in FIG. 2 (c), since the conductive paint 3 is filled from the direction of the arrow D, the conductive paint 3 is filled more than the conductive paint 3 placed on the filled edge portion 1a. The amount of the conductive paint 3 to be piled up on the edge portion 1a on the opposite side is small.

However, as in the present invention, the pad 6 is previously placed in this portion.
If the conductive coating material 3 is provided, the conductive coating material 3 is connected to the pad 6, so that the layer of the conductive coating material 3 overlaid on the edge portion 1a becomes thick as a whole, and cracks and the like are unlikely to occur from this point as well. Become.

Further, as shown in FIG. 3 (b), since the punch 50 is inserted from the pad 6 side, the end portion 6a and the edge portion 1a are
Has an inclined surface that is gently inclined inward, so that cracks and the like are unlikely to occur even if the amount of the conductive coating material 3 deposited on this portion is small.

On the other hand, as shown in FIG. 1, the edge portion 1a of the flexible substrate 1 on the side where the pad 6 is not formed protrudes at a slightly acute angle, but this edge portion 1a is made of flexible synthetic resin. Therefore, even if it protrudes, it does not become an acute angle, and even if the height of the projection once rises when the punch 50 enters, it becomes low because it is made of resin and returns to its original shape. That is, the protrusion of the edge portion 1a is low and has no acute angle, and is soft because it is made of resin. Moreover, since the conductive paint 3 deposited on this side is the side on which the conductive paint 3 is filled, the layer is thick, and cracks and the like are unlikely to occur when the two are combined.

〔The invention's effect〕

As described in detail above, according to the method for manufacturing a through hole for a flexible substrate according to the present invention, two layers of conductive material are interposed between the edge portions at both ends of the through hole formed in the flexible substrate and the outside. As a result, the portion can be strengthened, cracks and the like are less likely to occur, and therefore, there is an excellent effect that an increase in the resistance value and a conductive defect are less likely to occur in the through hole portion.

In addition, a pad is provided in advance only on one surface side of the through hole, a punch is formed on the pad from the surface side on which the pad is formed to form a through hole, and then a surface of the flexible substrate on which the punch is inserted is formed. Is to fill the inside of the through hole with conductive paint from the opposite surface side (that is, the surface side where the pad is not formed) to a position beyond the edge portions of both ends of the through hole. Further, cracks are less likely to occur, and it is suitable for use as a through hole for a flexible substrate having flexibility.

The amount of conductive paint deposited on the edge portion opposite to the side where the conductive paint is filled is small, but since the conductive paint is connected to the pad 6 previously provided on this surface side, The layer of the conductive coating material that is deposited on the edge portion becomes thick, and cracks and the like are less likely to occur from this point as well.

Since the punch is inserted from the side where the pad is provided, the edge part of the through hole on the side where the punch is inserted and the end of the pad are inclined surfaces that are gently inclined inward.
Even if the amount of the conductive paint deposited on this portion is small, cracks and the like are less likely to occur.

The edge portion of the through hole on the side of the flexible substrate on which the pad is not formed protrudes at a slightly acute angle.However, since this edge portion is made of a synthetic resin having flexibility, it is not low and has an acute angle. Because it is soft. In addition, the conductive paint deposited on this side is thick on the side where the conductive paint is filled, so that the layer is thick, and cracks and the like are unlikely to occur on this side as well.

[Brief description of drawings]

FIG. 1 is a side sectional view showing the structure of a through hole manufactured by using the method for manufacturing a through hole for a flexible substrate according to the present invention, FIG. 2 is a view showing the method for manufacturing this through hole, and FIG. The figure which expands and shows the C section of FIG.2 (b) when the punch 50 is thrust into the board | substrate 1.
FIG. 4 is a side sectional view showing the structure of a conventional through hole, and FIG. 5 is an enlarged view of a portion A shown in FIG.

Claims (1)

[Claims] 1. A first step of forming a pad made of a conductive thin film on only one surface of a flexible substrate made of a synthetic resin film having flexibility, and a step of forming the pad of the flexible substrate from the side where the pad is formed. A second step of forming a through hole through the pad by penetrating the punch into the pad and the flexible substrate, and from the surface opposite to the surface of the flexible substrate where the punch is inserted into the through hole. A third step of filling the conductive paint to a position beyond the edge portions of both ends of the through hole, and printing a circuit pattern so as to cover the entire surface of the conductive paint exposed on both sides of the flexible substrate. And a fourth step for manufacturing a through-hole for a flexible substrate.