TWI772090B - Membrane circuit board - Google Patents

Abstract

The present invention discloses a membrane circuit board including a first membrane substrate, a second membrane substrate, an extended membrane substrate and a protective film. The first membrane substrate has a first circuit pattern. The second membrane substrate has a second circuit pattern, and there is an interval distance between the second circuit pattern and the first circuit pattern. The extended membrane substrate extends from one side of the second membrane substrate. The extended membrane substrate has a plurality of conductive parts extending from the second circuit pattern, and each conductive part is covered with a carbon ink layer on a side away from the second membrane substrate. The protective film covers the conductive parts and the carbon ink layers. Part of each carbon ink layer is exposed on the protective film, and there is an overlapping area between the protective film and each carbon ink layer. The length of the overlapping area is greater than the length of each carbon ink layer exposed to the protective film.

Description

Thin film circuit board

The present invention relates to the field of input devices, in particular to a thin film circuit board applied to the input device.

With the rapid development of science and technology, the vigorous development of electronic equipment has brought a lot of convenience to human life. Therefore, how to make the operation of electronic equipment more humane is an important issue. Common input devices of electronic equipment include a mouse device, a keyboard device, and a trackball device, among which the keyboard device allows users to directly input characters and symbols to the computer, and thus has received considerable attention.

Most of the conventional keyboard devices include a key base plate, a thin-film circuit board, and a plurality of key structures. The thin-film circuit board includes a plurality of membrane switches, and the membrane switches correspond to the key structures respectively. Each key structure includes a keycap, a scissor-type connecting element and an elastic element. The scissors-type connecting element is connected between the keycap and the key bottom plate, and the scissor-type connecting element includes a first frame and a second frame that can swing relative to each other. , the elastic element is arranged between the key cap and the film circuit board, and the elastic element has a top. When the keycap of any key structure is pressed and moves downward relative to the key bottom plate, the first frame and the second frame of the scissor-type connecting element will be changed from the open and closed state to the overlapping state, and the keys that move downward will The cap will squeeze the elastic element, so that the top of the elastic element is pressed against the top of the elastic element and triggers the corresponding membrane switch, so that the corresponding membrane switch achieves electrical conduction, and when the key cap of the key structure is no longer pressed, the key The cap will move upward relative to the key bottom plate in response to the elastic force of the elastic element. At this time, the first frame and the second frame will change from the overlapping state to the opening and closing state, and the key cap will return to its original position.

Please refer to FIG. 1 , which is a schematic side view of a partial structure of a thin film circuit board of a conventional keyboard device from a viewing angle. As shown in FIG. 1 , the thin-film circuit board 1 includes an upper-layer thin-film substrate 11 , a lower-layer thin-film substrate 12 , and a middle-layer thin-film substrate 13 interposed between the upper-layer thin-film substrate 11 and the lower-layer thin-film substrate 12 . The lower surface of the upper film substrate 11 has a first circuit pattern 110 , and the first circuit pattern 110 has a plurality of upper contacts 1101 and a plurality of silver glue lines 1102 respectively corresponding to the above-mentioned key structures. The upper surface of the lower film substrate 12 has a second circuit pattern 120 , and the second circuit pattern 120 has a plurality of lower contacts 1201 and a plurality of lower silver glue lines 1202 respectively corresponding to the upper contacts 1101 . In addition, the middle-layer thin film substrate 13 has a plurality of openings 130 corresponding to the upper contacts 1101 and the lower contacts 1201 respectively. Each of the above-mentioned upper contacts 1101 and its corresponding lower contacts 1201 together form the above-mentioned membrane switch.

Please refer to FIG. 2 , which is a schematic side view of a partial structure of the thin film circuit board shown in FIG. 1 from another viewing angle. As shown in FIG. 2 , the lower film substrate 12 of the thin film circuit board 1 further includes an extension portion 14 , and at least part of the lower silver glue lines 1202 of the second circuit pattern 120 are disposed on the extension portion 14 to form a plurality of pins. Wherein, a carbon ink protective layer 15 for protecting the lower silver glue circuit 1202 is laid above each pin. When these pins are plugged with a connector (not shown), the connector can pierce the carbon ink protective layer 15 to contact the lower silver glue line 1202 to form electrical conduction. The disadvantage of the conventional thin film circuit board 1 is that the sulfur-containing air will enter the thin film circuit board 1 and contact the upper silver glue line 1102 of the first circuit pattern 110 and the lower silver glue line 1202 of the second circuit pattern 120, so that the The upper silver glue line 1102 and the lower silver glue line 1202 are gradually vulcanized to form silver sulfide, which will increase the conductive impedance and make the upper silver glue line 1102 and the lower silver glue line 1202 lose the function of conducting electronic signals. Therefore, how to improve the above-mentioned problems is really the focus of the relevant personnel in the art.

One of the objectives of the present invention is to provide a thin film circuit board with a structural design to prevent the intrusion of sulfur-containing gas or other reactive gases.

Other objects and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

To achieve one or part or all of the above objectives or other objectives, the present invention provides a thin film circuit board, which includes a first thin film substrate, a second thin film substrate, an extended thin film substrate and a protective film. The first thin film substrate has a first circuit pattern. The second thin film substrate is disposed relative to the first thin film substrate, and the second thin film substrate has a second circuit pattern. There is a separation distance between the second circuit pattern and the first circuit pattern. The extended film substrate extends from one side of the second film substrate, the extended film substrate has a plurality of conductive parts, these conductive parts extend from the second circuit pattern, and each conductive part is on a side away from the second film substrate Covered with carbon ink layer. The protective film covers the conductive parts and the carbon ink layers, a part of each carbon ink layer is exposed to the protective film, and there is an overlapping area between the protective film and each carbon ink layer, and the length of the overlapping area is greater than that of each carbon ink layer The part is exposed to the length of the protective film.

In an embodiment of the present invention, the length of the above-mentioned overlapping area is between 6 mm and 20 mm.

In an embodiment of the present invention, the first circuit pattern of the first thin film substrate includes a first contact and a first metal circuit, and the second circuit pattern of the second thin film substrate includes a second contact and a second metal circuit , the first contact and the second contact together form a thin film switch, and the conductive parts of the extended thin film substrate are extended from the second metal circuit.

In an embodiment of the present invention, at least one of the first metal lines of the first circuit pattern and the second metal lines of the second circuit pattern is a silver paste line.

In an embodiment of the present invention, the above-mentioned thin film circuit board further includes a spacer substrate. The spacer substrate is disposed between the first film substrate and the second film substrate, so that there is a distance between the first circuit pattern and the second circuit pattern, and the spacer substrate has an opening relative to the first contact and the second contact hole.

In an embodiment of the present invention, an air channel structure is provided between the carbon ink layer on each of the above-mentioned conductive parts and the carbon ink layer on another adjacent conductive part.

In an embodiment of the present invention, the above-mentioned thin film circuit board further includes a supporting bottom plate. The supporting bottom plate is disposed below the extending film substrate, and the supporting bottom plate is located on the side of the extending thin film substrate away from the second thin film substrate and corresponds to the carbon ink layer on each conductive part.

In an embodiment of the present invention, the above-mentioned thin film circuit board further includes a first protection structure. The first film substrate and the second film substrate are respectively formed by splicing at least two plate parts, and the first protection structure covers the joints of these plate parts.

In an embodiment of the present invention, the above-mentioned thin film circuit board further includes a second protection structure. The second protective structure is disposed on the extended thin film substrate and covers each carbon ink layer exposed on the protective film.

In an embodiment of the present invention, the above-mentioned first film substrate and second film substrate both use polyester film as the base material, and the film circuit board can be configured in the keyboard device.

In the thin film circuit board of the embodiment of the present invention, the carbon ink layer covering each conductive part is mainly extended, so that the length of the overlapping area between the protective film and each carbon ink layer is longer than that of each carbon ink layer. The length of the membrane, under such a structure design, the air channel structure between each carbon ink layer and another adjacent carbon ink layer is also relatively extended. In the case of extended air channel structure, it is difficult for sulfur-containing gas or other active gas. Intrusion into the interior of the thin film circuit board from the air channel structure, so as to increase the ability of the thin film circuit board to resist the damage of sulfur-containing gas or other reactive gases. In addition, protective structures can also be added at other positions of the thin film circuit board to increase the ability to resist the damage of sulfur-containing gas or other reactive gases, such as covering the protective structure at the junction between the multiple plate parts of the thin film substrate and when exposed to the protective structure. Each carbon ink layer of the film is covered with a protective structure.

In order to make the above-mentioned and other objects, features and advantages of the present invention more clearly understood, preferred embodiments are hereinafter described in detail in conjunction with the accompanying drawings.

Please refer to FIG. 3 to FIG. 5 . FIG. 3 is a schematic side view of a part of the structure of a thin film circuit board from a viewing angle according to an embodiment of the present invention. FIG. 4 is a schematic side view of a part of the structure of the thin film circuit board shown in FIG. 3 from another perspective. FIG. 5 is a schematic top view of the thin film circuit board shown in FIG. 4 .

As shown in FIGS. 3 to 5 , the thin film circuit board 2 of this embodiment includes a first thin film substrate 21 , a second thin film substrate 22 , an extended thin film substrate 23 and a protective film 24 . The first thin film substrate 21 has a first circuit pattern 210 . The second thin film substrate 22 is disposed relative to the first thin film substrate 21 , and the second thin film substrate 22 has second circuit patterns 220 , wherein there is a distance G between the second circuit patterns 220 and the first circuit patterns 210 . The extending film substrate 23 extends from one side of the second film substrate 22 . The extended film substrate 23 has a plurality of conductive parts 230 extending from the second circuit pattern 220 , and a carbon ink layer 25 is covered on the side of each conductive part 230 away from the second film substrate 22 . The protective film 24 is disposed above the extended film substrate 23 and covers the conductive parts and the carbon ink layers 25 . A portion of each carbon ink layer 25 is exposed to the protective film 24 , and the protective film 24 and each carbon ink layer 25 are separated. There is an overlap region R between them. In this embodiment, the length La of the overlapping region R is greater than the length Lb of each carbon ink layer 25 exposed to the protective film 24 .

The detailed structure of the thin film circuit board 2 according to the embodiment of the present invention will be further described below.

As shown in FIG. 3 to FIG. 5 , the first circuit pattern 210 of the first thin film substrate 21 of this embodiment includes a first contact 2101 and a first metal circuit 2102 . The second circuit pattern 220 of the second thin film substrate 22 includes second contacts 2201 and second metal lines 2202 . The first contact 2101 of the first circuit pattern 210 and the second contact 2201 of the second circuit pattern 220 together form a thin film switch, and the conductive parts 230 of the extended thin film substrate 23 extend from the second metal line 2202 of the second circuit pattern 220 extended out. In this embodiment, the first metal lines 2102 of the first circuit pattern 210 are, for example, silver paste lines, and the second metal lines 2202 of the second circuit pattern 220 are, for example, silver paste lines, but the invention is not limited thereto.

As shown in FIG. 3 to FIG. 5 , the thin film circuit substrate 2 of this embodiment further includes a spacer substrate 26 . The spacer substrate 26 is disposed between the first thin film substrate 21 and the second thin film substrate 22 , so that the first circuit pattern 210 on the first thin film substrate 21 and the second circuit pattern 220 on the second thin film substrate 22 are separated from each other. There is a separation distance G between them. In this embodiment, the spacer substrate 26 has an opening 260 , and the opening 260 is opposite to the first contact 2101 of the first circuit pattern 210 and the second contact 2201 of the second circuit pattern 220 .

It should be noted that, the first film substrate 21 and the second film substrate 22 in this embodiment use polyester film (PET) as the base material, for example, and the extended film substrate 23 extending from the second film substrate 22 is used. The base material is the same as the second thin film substrate 22, but the present invention is not limited to this. In this embodiment, the first circuit pattern 210 and the second circuit pattern 220 are respectively formed on the surfaces of the first thin film substrate 21 and the second thin film substrate 22 according to the specified circuit pattern by printing, for example. In addition, from the second circuit pattern 220 The extended conductive portions 230 are, for example, pins that can be electrically connected to a connector (not shown), but the invention is not limited thereto. The thin-film circuit board 2 of this embodiment can be configured on an external keyboard (for example, a PS2 interface keyboard or a USB interface keyboard) used in a desktop computer or a built-in keyboard used in a notebook computer and a laptop computer. However, the present invention is not limited to this, that is, the concept of the thin film circuit board 2 of the embodiment of the present invention can be applied to any electronic product using the thin film circuit board 2 as a signal input interface.

Specifically, the thin film circuit board 2 of the present embodiment is disposed below a plurality of key structures (not shown) in the keyboard device. Generally speaking, the key structure includes elements such as a key cap, a scissor-type connecting component, an elastic member, and the like, and the connection relationship between these elements is not described in detail here. Between the first circuit pattern 210 on the first thin film substrate 21 and the second circuit pattern 220 on the second thin film substrate 22 can form a plurality of thin film switches, that is, a plurality of first contacts of the first circuit pattern 210 The membrane switches are formed between the plurality of second contacts 2201 of the second circuit pattern 220 , and the membrane switches correspond to the key structures respectively. The first contacts 2101 are respectively in contact with the second contacts 2201 through the corresponding openings 260 on the spacer substrate 26 . Specifically, when the keycap of the key structure is not pressed, the first contact 2101 on the first thin film substrate 21 and the second contact 2201 on the second thin film substrate 22 are separated from the two sides of the spacer substrate 26 and electrically Sexual separation. When the key cap is pressed to move toward the thin film circuit board 2 , the key cap will directly or indirectly push the first thin film substrate 21 and partially enter the opening 260 of the spacer substrate 26 , so that the first contact on the first thin film substrate 21 2101 passes through the opening 260 of the spacer substrate 26 to contact the second contact 2201 on the second thin film substrate 22 . Thereby, the triggered membrane switch immediately generates a trigger signal corresponding to the pressed key structure.

As shown in FIG. 3 and FIG. 4 , the thin film circuit board 2 of this embodiment further includes a support bottom plate 27 . The support bottom plate 27 is disposed below the extended film substrate 23 , and the support bottom plate 27 is located on the side of the extended film substrate 23 away from the second thin film substrate 22 and corresponds to the carbon ink layers 25 covering each conductive portion 230 . Specifically, the support base plate 27 of this embodiment extends along the direction D and has a first length L1, and the carbon ink layers 25 covering each conductive portion 230 extend along the direction D and have a second length L2, The first length L1 of the support base plate 27 is greater than the second length L2 of each carbon ink layer 25 . In other words, the support base plate 27 of this embodiment has a projection area projected vertically upward, and the carbon layers covering each of the conductive parts 230 The ink layer 25 will be located in the projection area. The function of the support base plate 27 is to increase the structural strength of the carbon ink layers 25. During the process of connecting the conductive parts 230 covered with the carbon ink layers 25 to the connectors (not shown), the support base plate 27 can prevent these carbon ink layers 25 from being inserted into the connector (not shown). The ink layer 25 is bent and broken.

As shown in FIG. 4 and FIG. 5 , the carbon ink layer 25 covering each conductive portion 230 in this embodiment has an air channel structure A between the adjacent carbon ink layer 25 covering another conductive portion 230 . For example, in this embodiment, the total length of the carbon ink layer 25 covering each conductive portion 230 (that is, the above-mentioned first length L1 ) is 10 mm, and each of the carbon ink layers exposed outside the protective film 24 has a total length of 10 mm. The length Lb of the carbon ink layer 25 is between 4 mm, and the length La of the overlapping region R between the protective film 24 and each carbon ink layer 25 is 6 mm, that is to say, the air channel structure A of this embodiment is The total length of the airway structure A is 10 mm, and the length of the airway structure A covered by the protective film 24 is 6 mm. The main purpose of the present invention is to extend the length of the airway structure A covered by the protective film 24, and the length of the airway structure A covered by the protective film 24 is further extended from the conventional range of 1 mm to 1.3 mm to 6 mm. mm, under such a structural design, the sulfur-containing gas or other active gas is less likely to pass through the air channel structure A and intrude into the interior of the thin-film circuit board 2, that is, the sulfur-containing gas or other active gas will be confined in the extended air channel. structure A without outflow from the airway structure A.

It should be noted that the length La of the overlapping region R between the protective film 24 and each carbon ink layer 25 is 6 mm, which is only one embodiment of the present invention, and the overlapping region R is not limited in the present invention. On the premise that the length La of the overlapping region R is greater than the length Lb of each carbon ink layer 25 exposed outside the protective film 24, the length of the overlapping region R between the protective film 24 and each carbon ink layer 25 La can be extended to the required length according to actual needs. For example, under the condition that the length Lb of each carbon ink layer 25 exposed outside the protective film 24 remains unchanged, the protective film 24 and each The length La of the overlapping region R of the layer 25 can be extended to 20 mm, that is, the length La of the overlapping region R between 6 mm and 20 mm can be implemented.

Please refer to FIG. 6 , which is a schematic top view of the first thin film substrate 21 shown in FIG. 3 . As shown in FIG. 6 , the thin film circuit board 2 of this embodiment further includes a first protection structure 28 . In this embodiment, the first film substrate 21 and the second film substrate 22 are formed by splicing two plate parts B1 and B2 respectively. In FIG. 6 , the first film substrate 21 is taken as an example for illustration. The plate part B1 and the plate part B2 of 21 have a joint C after being spliced, and the first protective structure 28 covers the joint C between the plate part B1 and the plate part B2, so as to prevent sulfur-containing gas or other active gas from passing from the plate. The joint C between the portion B1 and the plate portion B2 flows into the film wiring board 2 . It should be noted that the present invention does not limit the number of plate parts. In other embodiments, the first film substrate 21 and the second film substrate 22 are, for example, formed by splicing two or more plate parts, respectively. Regardless of the number of plate parts, the first protection structure 28 can be covered on the joints formed by splicing these plate parts. In this embodiment, the first protection structure 28 is, for example, UV glue or other filling materials, but the invention is not limited thereto.

Please refer to FIG. 7 , which is a schematic side view of a part of the structure of a thin film circuit board from a viewing angle according to another embodiment of the present invention. As shown in FIG. 7 , the thin film circuit board 2 a of this embodiment is similar to the thin film circuit board 2 shown in FIGS. 3 to 5 , except that the thin film circuit board 2 a of this embodiment further includes a second protection structure 29 . The second protection structure 29 is disposed on the extended film substrate 23 , and the second protection structure 29 covers each carbon ink layer 25 exposed outside the protection film 24 . With such a structural design, it is possible to further prevent sulfur-containing gas or other reactive gas from intruding into the interior of the thin-film circuit board 2a by passing through the air channel structure A. As shown in FIG. In this embodiment, the second protection structure 29 is, for example, UV glue or water glue, but the invention is not limited to this.

To sum up, in the thin film circuit board of the embodiment of the present invention, the carbon ink layer covering each conductive portion is mainly extended, so that the length of the overlapping area between the protective film and each carbon ink layer is greater than that of each carbon ink layer The part is exposed to the length of the protective film. Under this structural design, the air channel structure between each carbon ink layer and another adjacent carbon ink layer is also relatively extended. When the air channel structure is extended, the sulfur-containing gas or Other reactive gases are less likely to penetrate into the interior of the thin-film circuit board from the air channel structure, thereby increasing the ability of the thin-film circuit board to resist damage by sulfur-containing gas or other reactive gases. In addition, protective structures can also be added at other positions of the thin film circuit board to increase the ability to resist the damage of sulfur-containing gas or other reactive gases, such as covering the protective structure at the junction between the multiple plate parts of the thin film substrate and when exposed to the protective structure. Each carbon ink layer of the film is covered with a protective structure.

However, the above are only preferred embodiments of the present invention, and should not limit the scope of the present invention, that is, any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the description of the invention, All still fall within the scope of the patent of the present invention. In addition, any embodiment of the present invention or the scope of the claims is not required to achieve all of the objects or advantages or features disclosed herein. In addition, the abstract section and the title are only used to aid the search of patent documents and are not intended to limit the scope of the present invention. In addition, terms such as "first" and "second" mentioned in this specification or the scope of the patent application are only used to name the elements or to distinguish different embodiments or scopes, and are not used to limit the number of elements. upper or lower limit.

1, 2, 2a: Thin film circuit board 11: Upper film substrate 12: Lower film substrate 13: Middle layer thin film substrate 14: Extensions 15: Carbon ink protective layer 21: The first thin film substrate 22: Second thin film substrate 23: Extended film substrate 24: Protective film 25: Carbon ink layer 26: Spacer substrate 27: Support bottom plate 28: The first protection structure 29: Second protection structure 110, 210: The first circuit pattern 120, 220: The second circuit pattern 130: Opening 230: Conductive part 260: Opening 1101: Upper Contact 1102: Silver glue line 1201: Lower Contact 1202: Lower silver glue circuit 2101: First Contact 2102: First Metal Wire 2201: Second Contact 2202: Second Metal Wire A: Airway structure D: direction G: separation distance R: overlapping area L1: first length L2: second length La, Lb: length

FIG. 1 is a schematic side view of a partial structure of a thin film circuit board of a conventional keyboard device from a perspective. FIG. 2 is a schematic side view of a partial structure of the thin film circuit board shown in FIG. 1 from another perspective. FIG. 3 is a schematic side view of a partial structure of a thin film circuit board from a viewing angle according to an embodiment of the present invention. FIG. 4 is a schematic side view of a part of the structure of the thin film circuit board shown in FIG. 3 from another perspective. FIG. 5 is a schematic top view of the thin film circuit board shown in FIG. 4 . FIG. 6 is a schematic top view of the first thin film substrate shown in FIG. 3 . FIG. 7 is a schematic side view of a partial structure of a thin film circuit board from a viewing angle according to another embodiment of the present invention.

2: Thin film circuit board

21: The first thin film substrate

22: Second thin film substrate

23: Extended film substrate

24: Protective film

25: Carbon ink layer

26: Spacer substrate

27: Support bottom plate

220: Second Circuit Pattern

230: Conductive part

2202: Second Metal Wire

D: direction

R: overlapping area

L1: first length

L2: second length

La, Lb: length

Claims (10)

A thin film circuit board, comprising: a first film substrate with a first circuit pattern; a second thin-film substrate disposed relative to the first thin-film substrate, the second thin-film substrate has a second circuit pattern, and there is a spacing distance between the second circuit pattern and the first circuit pattern; an extended film substrate extending from one side of the second film substrate, the extended film substrate has a plurality of conductive parts, the conductive parts extend from the second circuit pattern, and each conductive part is far away from the first One side of the two thin film substrates is covered with a carbon ink layer; and a protective film covering the conductive parts and the carbon ink layers, a portion of each carbon ink layer is exposed to the protective film, and there is an overlapping area between the protective film and each carbon ink layer, and the overlapping area The length of each carbon ink layer is greater than the length of the portion of each carbon ink layer exposed to the protective film. The thin film circuit board of claim 1, wherein the length of the overlapping region is between 6 mm and 20 mm. The thin film circuit board of claim 1, wherein the first circuit pattern of the first thin film substrate includes a first contact and a first metal circuit, and the second circuit pattern of the second thin film substrate includes a first Two contacts and a second metal circuit, the first contact and the second contact together form a thin film switch, and the conductive parts of the extended thin film substrate extend from the second metal circuit. The thin film circuit board of claim 3, wherein at least one of the first metal circuit of the first circuit pattern and the second metal circuit of the second circuit pattern is a silver paste circuit. The thin film circuit board as claimed in claim 3, further comprising a spacer substrate disposed between the first film substrate and the second film substrate, so that the first circuit pattern and the second circuit pattern are connected to each other. There is the spacing distance therebetween, and the spacer substrate has an opening corresponding to the first contact and the second contact. The thin film circuit board of claim 1, wherein an air channel structure is formed between the carbon ink layer on each conductive portion and the carbon ink layer on another adjacent conductive portion. The thin film circuit board as claimed in claim 1, further comprising a supporting bottom plate, the supporting bottom plate is disposed below the extending thin film substrate, and the supporting bottom plate is located on a side of the extending thin film substrate away from the second thin film substrate, and is connected to each of the extending thin film substrates. The carbon ink layers on a conductive portion correspond to each other. The thin-film circuit board as claimed in claim 1, further comprising a first protective structure, the first thin-film substrate and the second thin-film substrate are respectively formed by splicing at least two plate parts, and the first protective structure covers the plates on the junction of the part. The thin-film circuit board of claim 1, further comprising a second protective structure, the second protective structure is disposed on the extended thin-film substrate and covers each carbon ink layer exposed on the protective film. The thin-film circuit board of claim 1, wherein the first thin-film substrate and the second thin-film substrate both use polyester film as the base material, and the thin-film circuit board can be configured in a keyboard device.

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