JP2004319769A - Wiring base material and electric equipment and switch device provided with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring base material for which wiring and a connection terminal are not peeled off from a base material main body even in the case of performing energizing under the environment of a high temperature and high humidity, and to provide electric equipment and a switch device provided with it. <P>SOLUTION: For the wiring base material, two or more lines of wiring are formed on a substrate main body 7 composed of PET, the base end of the connection terminal is formed in an exposed state at each wiring, and a coating film 11 composed of a hard-to-hydrolyze high polymer resin is formed between the tips 9b of the connection terminals on the substrate main body 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３６】
表１によれば、耐食性については、被覆膜の厚みが６μｍ以上（実施例２〜４）で優れており、厚みが１〜５μｍ（実施例１）では若干低下するものの実用上問題の無いレベルであった。一方、比較例のものは耐食性に劣ったものであった。
また、導電性については、被覆膜の厚みが１０μｍ以下（実施例１、２及び比較例）で優れており、厚みが１１〜１５μｍ（実施例３）では導電性が低下しているものの実用上問題の無いレベルであった。また、実施例４のものは導電性が低下しており、実用上問題が生じる虞のあるレベルであった。
以上により、耐食性及び導電性の双方に優れた被覆膜の厚みは６〜１０μｍであり、これに次ぐ被覆膜の厚みは１〜５μｍ及び１１〜１５μｍであった。
【００３７】
【発明の効果】
以上詳述したように、本発明の配線基材によれば、脱水縮合によって合成された第１の高分子樹脂からなる基材本体上かつ前記複数の接続端子の間に、第２の高分子樹脂からなる被覆膜を形成したので、この基材本体と接続端子との界面を封止することができ、この界面に外部の水分が触れる虞も無くなる。
したがって、高温高湿の環境下において長時間通電された場合であっても、接続端子が基材本体から剥離されたり分離される虞がない。
【００３８】
本発明の配線基材によれば、接続端子の外部と電気的に接触する領域を除く部分を、第２の高分子樹脂からなる被覆膜にて被覆したので、この基材本体と接続端子との界面を封止することができ、この界面に外部の水分が触れる虞も無くなる。
したがって、高温高湿の環境下において長時間通電された場合であっても、接続端子が基材本体から剥離されたり分離される虞がない。
【００３９】
本発明の電気機器またはスイッチ装置は、本発明の配線基材を備えたので、高温高湿の環境下で通電使用した場合においても、配線や接続端子が基材本体から剥離や分離するのを防止することができ、その結果、接続部分の接続不良を生じさせない電気機器やスイッチ装置を提供することができる。
【図面の簡単な説明】
【図１】本発明に係る第１実施形態の配線基材を備えたスイッチ装置を示す平面図である。
【図２】本発明に係る第１実施形態のスイッチ装置におけるフレキシブルプリント基板の先端部分を示す平面図である。
【図３】本発明に係る第１実施形態のスイッチ装置におけるフレキシブルプリント基板の先端部分を示す縦断面図である。
【図４】本発明に係る第１実施形態のスイッチ装置におけるフレキシブルプリント基板の先端部分を示す横断面図である。
【図５】本発明に係る第１実施形態のスイッチ装置が設けられる電気機器の一例を示す斜視図である。
【図６】本発明に係る第１実施形態のスイッチ装置におけるフレキシブルプリント基板の先端部分の変形例を示す平面図である。
【図７】本発明に係る第２実施形態のフレキシブルプリント基板の先端部分を示す平面図である。
【図８】本発明に係る第２実施形態のフレキシブルプリント基板の先端部分を示す縦断面図である。
【符号の説明】
Ａ…スイッチ装置、Ｂ…電気機器、１…スイッチ本体部、２、２１、３１…フレキシブルプリント基板（配線基材）、７…基板本体（基材本体）、８…配線、９…接続端子、９ａ…基端部、９ｃ…電気的に接触する領域、１０…保護層、１１、２２、３２…被覆膜、３３…コネクタ端子、３４…開口。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a wiring substrate in which even if a wiring substrate in which connection terminals are exposed is energized for a long time in a high-humidity environment, the wiring and the connection terminals are not likely to be separated from the base material body as a base. The present invention relates to an electric device and a switch device having the same.
[0002]
[Prior art]
Various printed circuit boards or flexible printed circuit boards mounted on electronic devices have also been reduced in size and weight in accordance with miniaturization and weight reduction of electronic devices. With the miniaturization of these wiring boards, the miniaturization of the terminal portions of the wiring boards has been promoted, and wiring boards having a terminal part wiring pitch of about 0.5 mm have been used. From such a background, conventionally, for the purpose of increasing the density of connection terminals, there has been proposed a structure in which terminal pitch intervals are shifted to increase the density. (See Patent Document 1)
[0003]
[Patent Document 1]
JP-A-6-13154
As an example of a conventional printed wiring board, there is a film printed wiring board used for a membrane switch or the like.
In this film printed wiring board, a wiring made of a plurality of metal conductors is formed in parallel with each other on a strip-shaped base body made of a flexible polymer resin such as polyethylene terephthalate (PET). A connection terminal is formed at one end of each. These wirings are covered with an organic polymer resin having high moisture resistance, and the connection terminals formed at one end of each of these wirings and the base material body thereunder are exposed.
[0005]
[Problems to be solved by the invention]
By the way, in the conventional film printed wiring board, since the connection terminals and the base body under the connection terminals are exposed, for example, a voltage is applied between the connection terminals in a high-temperature and high-humidity environment such as 65 ° C. and 90%. When the voltage is applied, the base body near the connection terminal on the negative electrode side is hydrolyzed and degraded by the moisture in the environment, so that there is a problem that the connection terminal peels off from the surface of the base body and floats. Was.
[0006]
This phenomenon is considered to be due to the causes described below.
In a high-temperature, high-humidity environment, a large amount of moisture exists around the connection terminals. Therefore, when a voltage of about several volts is applied between the exposed connection terminals for a long time, the voltage around the connection terminals is reduced by this voltage. The water is electrolyzed, and hydrogen ions are generated near the connection terminal on the positive electrode side and hydroxyl groups are generated near the connection terminal on the negative electrode side. Accordingly, the water near the connection terminal on the negative electrode side becomes alkaline due to the generated hydroxyl groups, and the surface of the polyethylene terephthalate (PET) base material body which is the base of the connection terminal is hydrolyzed by the alkaline water. The connection terminals are eluted in the water, and as a result, the connection terminals are lifted off the surface of the base material body and peeled off.
[0007]
Since this polyethylene terephthalate (PET) is generally produced by dehydrating and condensing terephthalic acid and ethylene glycol, it is liable to be hydrolyzed in the presence of moisture, and this hydrolysis reaction is carried out particularly in an alkaline environment. Moreover, it is believed that it is accelerated at high temperatures.
In addition, not only polyethylene terephthalate (PET) but also various wiring boards using a polymer resin produced by dehydration condensation of polyimide, phenol resin, polyethylene naphthalate, etc., in a high temperature and high humidity environment, the same phenomenon. Is believed to happen.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is intended to supply electric current to connection terminals of wiring formed on a base material body made of a polymer resin such as polyethylene terephthalate (PET) in a high-temperature and high-humidity environment. Even in such a case, it is an object of the present invention to provide a wiring base material in which wiring and connection terminals are not peeled off from the base material body and there is no possibility that a connection failure occurs, and an electric device and a switch device including the wiring base material.
[0009]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION In order to solve the above-described problems, the present invention employs the following wiring base material, and electrical equipment and a switch device including the same.
That is, in the wiring base material of the present invention, a plurality of wirings are formed on a base body made of a first polymer resin synthesized by dehydration condensation, and the plurality of wirings are formed on at least a part of the base body. Each connection terminal is formed in an exposed state, and a coating film made of a second polymer resin is formed on at least the base body and between the plurality of connection terminals.
[0010]
In this wiring base material, a coating film made of a second polymer resin is formed on a base material body made of a first polymer resin synthesized by dehydration condensation and between the plurality of connection terminals. In addition, the interface between the base body and the connection terminal is sealed, so that there is no danger of external moisture touching this interface.
As described above, by protecting the interface between the base body and the connection terminal with the coating film made of the second polymer resin, it is possible to prevent the contact with the moisture in the external environment, and the high temperature and the high temperature can be prevented. Even when electricity is supplied between the connection terminals in a humid environment, there is no possibility that the surface portion of the substrate body is hydrolyzed. Therefore, even when the power is supplied for a long time in a high-temperature and high-humidity environment, the connection terminal is not separated or separated from the base body.
[0011]
In order to achieve the above object, the wiring substrate of the present invention has a plurality of wirings formed on a substrate body made of a first polymer resin synthesized by dehydration condensation, and at least a plurality of wirings are formed on the substrate body. The connection terminals of each of the plurality of wirings are formed in an exposed state, and these connection terminals are covered with a coating film made of a second polymer resin except for a region that is in electrical contact with the outside. It is characterized by becoming.
[0012]
In this wiring base material, a portion excluding a region electrically contacting the outside of the connection terminal is covered with a coating film made of a second polymer resin, so that an interface between the base material body and the connection terminal is formed. Is sealed, and there is no danger of external moisture touching this interface.
As described above, by protecting the portion of the base film body and the connection terminal except for the area electrically contacting the outside with the coating film made of the second polymer resin, the base body body and the connection terminal can be protected from the external environment. This makes it possible to prevent the contact with the moisture therein, so that even when electricity is supplied between the connection terminals in a high-temperature and high-humidity environment, there is no possibility that the surface portion of the base material body is hydrolyzed. Therefore, even when the power is supplied for a long time in a high-temperature and high-humidity environment, the connection terminal is not separated or separated from the base body.
[0013]
In the wiring base material of the present invention, the first polymer resin is preferably made of a flexible polymer resin, and the flexible polymer resin is polyethylene terephthalate, polyimide, phenol resin, It is preferred to be composed of any one of polyethylene naphthalate.
[0014]
Since these polymer resins, in particular, polyethylene terephthalate, polyimide, phenol resin, and polyethylene naphthalate are produced with a dehydration reaction at the time of production, a hydrolysis reaction occurs on the negative electrode side by energization under a high temperature and high humidity environment. There is a possibility, which is effective for applying the present invention.
[0015]
In the wiring substrate of the present invention, the second polymer resin is preferably made of an addition polymerization type polymer resin, and the addition polymerization type polymer resin may be a thermoplastic resin, a thermosetting resin, -It is preferable to be composed of any one of an electron beam curable resin.
[0016]
This addition-polymerized polymer resin, in particular, a thermoplastic resin, a thermosetting resin, and an optical / electron beam curable resin has excellent water resistance. The ability to prevent contact of the base material is excellent, and there is no possibility that the surface portion of the base material body is hydrolyzed even when electricity is supplied between the connection terminals in an environment of high temperature and high humidity. Therefore, even when current is supplied for a long time in a high-temperature and high-humidity environment, there is no possibility that the connection terminal is peeled off or separated from the base body.
[0017]
An electric device according to the present invention includes the wiring base material according to the present invention.
A switch device according to the present invention includes the wiring substrate according to the present invention.
In these electric devices and switch devices, since the wiring base of the present invention is provided, there is a possibility that the wirings and connection terminals may be separated or separated from the base body even when used in a high-temperature and high-humidity environment. Thus, it is possible to provide an electric device or a switch device that does not cause connection failure of the connection portion.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a wiring base material, an electric device including the same, and a switch device according to the present invention will be described with reference to the drawings.
"First Embodiment"
FIG. 1 is a plan view showing a switch device provided with a wiring base material of the present embodiment, FIG. 2 is a plan view showing a front end portion of a flexible printed board (wiring base material) in the switch device, and FIG. And FIG. 4 is a cross-sectional view showing the leading end of the flexible printed circuit board.
In all of the drawings, the film thickness and dimensional ratio of each component are appropriately changed in order to make the drawings easy to see. In addition, it goes without saying that the present invention is not limited to the following embodiments.
[0019]
The switch device A includes a switch body 1 and a flexible printed circuit board (wiring base) 2 connected to the switch body 1.
The switch body 1 is provided with a board body 3, and the board body 3 is provided with a first switch section 5 and a second switch section 6 which are slidable. A flexible printed circuit board 2 having a belt-like flexibility connected to the switch lines of the switch units 5 and 6 is provided.
The flexible printed circuit board 2 is provided on a part of the outer surface of the electric device B in order to connect the switches 5 and 6 to an internal electric circuit of the electric device B such as a digital camera shown in FIG. is there.
[0020]
The flexible printed circuit board 2 includes a plurality of wirings 8, 8,... Made of a conductive material formed by applying a printing method such as a screen printing method on a belt-shaped flexible substrate body (base body) 7. Are formed at the leading end 7a of the substrate body 7 having a reduced width, and are connected to the ends of the wirings 8, 8,. , And the protective layer 10 made of a resist covering the connection portion with the connection terminals 9, 9,... And the coating formed between the exposed connection terminals 9, 9,. And a film 11.
[0021]
The substrate body 7 is a film made of a first polymer resin synthesized by dehydration condensation, and the first polymer resin is a flexible polymer resin such as terephthalic acid and ethylene glycol. And any one of polyethylene terephthalate (PET), polyimide, phenol resin and polyethylene naphthalate obtained by dehydration polymerization of
[0022]
The wiring 8 is made of a conductive material formed by a coating method such as a screen printing method in parallel at substantially equal intervals up to a portion near the front end portion 7a of the substrate body 7, and the conductive material is silver, gold, or the like. A metal material such as copper, platinum, or an alloy thereof is preferably used. Among these metal materials, a silver paste or a silver alloy paste that can be easily printed on the substrate body 7 by a screen printing method is preferably used.
[0023]
The connection terminal 9 is a band-shaped member formed such that its base end 9a is individually connected to the front end 8a of the wiring 8 and rides up, and is formed by a printing method such as a screen printing method. The connection terminal 9 is made of a conductive material like the wiring 8, and is generally made of a widely used conductive material for terminals similarly to the material forming the wiring 8. However, a conductive material which is excellent in abrasion resistance, corrosion resistance, and migration resistance and has low contact resistance because of contact with an external terminal is preferable.
[0024]
Migration is a phenomenon in which, when wirings made of a conductive material such as silver are formed at a narrow pitch, silver crystals grow between adjacent wirings due to elution of silver ions or the like and short-circuit the adjacent wirings. It is preferable to select a material that does not easily cause crystal growth, for example, a noble metal such as platinum or palladium or an alloy thereof.
[0025]
A protective layer 10 covers the surface of the substrate body 7 including the base end 9a of the connection terminal 9 and the wiring 8 and excluding the end 7a. Therefore, the tip 9b of the connection terminal 9 is exposed on the surface of the tip 7a of the substrate body 7.
The coating film 11 is formed on the front end portion 7a of the substrate main body 7 and between each of the exposed front end portions 9b of the connection terminals 9, and is a material which is hardly hydrolyzed even in the presence of moisture. A second polymer resin, for example, an addition polymerization type polymer resin such as an epoxy resin, a vinyl chloride resin, and an acrylic resin is suitably used. As the polymer resin of the addition polymerization type, any of a thermoplastic resin, a thermosetting resin, and a photo / electron beam curable resin is preferable in consideration of pattern accuracy, workability, and the like.
[0026]
In the present embodiment, since the coating film 11 is formed between the tip portions 9b of the plurality of connection terminals 9 that are exposed on the tip portions 7a of the substrate body 7, the plurality of connection terminals 9, 9, ... When the connection terminals 9, 9, ... are energized in the state where moisture exists in the respective tip portions 9b and their surroundings, the moisture is electrolyzed to generate hydroxyl groups, which may cause a temporary alkaline environment. Even if this happens, the coating film 11 protects the surface of the distal end portion 7a of the substrate main body 7 and the distal end portion 9b of the connection terminal 9, and there is no possibility that the distal end portion 7a of the substrate main body 7 is decomposed or dissolved. .. Are not separated or peeled off from the substrate main body 7.
[0027]
Therefore, if the switch device A or the electric device B is provided with the flexible printed circuit board 2 of the present embodiment, even if the electric current is applied for a long time in a high-temperature and high-humidity environment, the substrate body of the connection terminals 9, 9,. There is no risk of separation or separation from the wiring 7 and no connection failure at the connection portion of the wiring.
[0028]
FIG. 6 is a plan view showing a modified example of the flexible printed circuit board (wiring base material) according to the present embodiment. This flexible printed circuit board 21 is different from the above-described flexible printed circuit board 2 in that the distal end portion 9b of the connection terminal 9 is provided. Is that the coating film 22 is formed so as to surround.
This flexible printed circuit board 21 can also provide the same functions and effects as those of the flexible printed circuit board 2.
Moreover, since the surface of the substrate body 7 and the periphery of the distal end 9b of the connection terminal 9 are covered with the coating film 22, the distal end portion 7a of the substrate main body 7 is decomposed or dissolved as compared with the above-described coating film 11. The risk of occurrence is extremely reduced.
[0029]
"Second embodiment"
FIG. 7 is a plan view showing a flexible printed circuit board (wiring base material) of the present embodiment, and FIG. 8 is a longitudinal sectional view showing a front end portion of the flexible printed circuit board. The difference from the flexible printed circuit board 2 of the embodiment is that the surface of the substrate body 7 including the surface of the tip 9b of the connection terminal 9 is covered with a coating film 32, and the coating film 32 has an external connector terminal. An opening 34 is formed so that a region 9c electrically in contact with 33 is exposed, and the other points are exactly the same as those of the flexible printed circuit board 2 of the first embodiment.
[0030]
Also in the flexible printed circuit board 21 of the present embodiment, similarly to the first embodiment, the connection terminals 9, 9,. , There is no possibility that the tip 7a of the substrate body 7 is decomposed or dissolved. .. Are not separated or peeled off from the substrate main body 7.
[0031]
In addition, since the connection terminals 9 and the board body 7 are covered with the coating film 32 except for an area 9 c that is in electrical contact with the external connector terminals 33, moisture is not applied to the connection terminals 9 and the tip of the board body 7. Can be prevented from entering and adhering to the interface with the substrate 7a, and the connection terminals 9, 9,...
[0032]
【Example】
Using a flexible substrate made of polyethylene terephthalate (PET) having a thickness of 0.07 mm, a silver paste is applied on the flexible substrate by a screen printing method and heated to 150 ° C. to form a plurality of substrates each having a thickness of 10 μm and a width of 0.35 mm. The wiring is baked, and a 10 μm-thick epoxy resin layer is formed on the tip end side of each wiring located at the end of the flexible board, and a connection terminal having a length of 4 mm and a thickness of 0.01 mm made of Pd is formed thereon. A plurality of flexible printed boards having a configuration formed at a pitch of 0.5 mm so as to be connected to the above wirings were produced.
[0033]
Next, a liquid epoxy resin is poured onto each of the ends of the connection terminals that are exposed on the end of the substrate body of the flexible printed circuit board, and is heated and cured at 120 ° C. for 120 minutes. Then, a coating film was formed. Here, the thickness of the coating film was set to four values of 1 to 5 μm, 6 to 10 μm, 11 to 15 μm, and 16 to 20 μm, and Examples 1 to 4 were made. In addition, a device without a coating film was also prepared and used as a comparative example.
[0034]
Each of Examples 1 to 4 and Comparative Example was evaluated for corrosion resistance and conductivity (contact stability with a connector).
The corrosion resistance was evaluated by the change of the conduction resistance value at 60 ° C. and 90 to 95% RH over time under high temperature and high humidity conditions.
The conductivity was evaluated by inserting the flexible printed circuit board into the connector and measuring the conduction resistance between the flexible printed circuit board and the connector.
Table 1 shows the evaluation results of Examples 1 to 4 and Comparative Example.
[0035]
[Table 1]

[0036]
According to Table 1, the corrosion resistance is excellent when the thickness of the coating film is 6 μm or more (Examples 2 to 4) and slightly reduced when the thickness is 1 to 5 μm (Example 1), but there is no practical problem. Level. On the other hand, those of Comparative Examples were inferior in corrosion resistance.
The conductivity is excellent when the thickness of the coating film is 10 μm or less (Examples 1 and 2 and Comparative Example), and when the thickness is 11 to 15 μm (Example 3), the conductivity is low, but practical. It was a level without any problems. In the case of Example 4, the conductivity was lowered, and the level was at a level that might cause a practical problem.
As described above, the thickness of the coating film excellent in both the corrosion resistance and the conductivity was 6 to 10 μm, and the thickness of the coating film next to this was 1 to 5 μm and 11 to 15 μm.
[0037]
【The invention's effect】
As described above in detail, according to the wiring base material of the present invention, the second polymer is provided between the plurality of connection terminals on the base body made of the first polymer resin synthesized by dehydration condensation. Since the coating film made of resin is formed, the interface between the base material body and the connection terminal can be sealed, and there is no danger of external moisture touching this interface.
Therefore, even when the power is supplied for a long time in a high-temperature and high-humidity environment, there is no possibility that the connection terminal is peeled off or separated from the base body.
[0038]
According to the wiring base material of the present invention, since the portion excluding the region that electrically contacts the outside of the connection terminal is covered with the coating film made of the second polymer resin, the base body and the connection terminal are covered. Interface can be sealed, and there is no danger of external moisture coming into contact with this interface.
Therefore, even when the power is supplied for a long time in a high-temperature and high-humidity environment, there is no possibility that the connection terminal is peeled off or separated from the base body.
[0039]
Since the electric device or the switch device of the present invention includes the wiring base of the present invention, even when used in a high-temperature and high-humidity environment, it is possible to prevent the wiring and the connection terminal from being separated or separated from the base body. As a result, it is possible to provide an electric device or a switch device that does not cause a connection failure of a connection portion.
[Brief description of the drawings]
FIG. 1 is a plan view showing a switch device provided with a wiring base material according to a first embodiment of the present invention.
FIG. 2 is a plan view showing a leading end portion of a flexible printed circuit board in the switch device according to the first embodiment of the present invention.
FIG. 3 is a longitudinal sectional view showing a leading end portion of a flexible printed board in the switch device according to the first embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a tip portion of a flexible printed circuit board in the switch device according to the first embodiment of the present invention.
FIG. 5 is a perspective view showing an example of an electric device provided with the switch device according to the first embodiment of the present invention.
FIG. 6 is a plan view showing a modified example of a tip portion of a flexible printed circuit board in the switch device according to the first embodiment of the present invention.
FIG. 7 is a plan view showing a distal end portion of a flexible printed circuit board according to a second embodiment of the present invention.
FIG. 8 is a longitudinal sectional view showing a front end portion of a flexible printed circuit board according to a second embodiment of the present invention.
[Explanation of symbols]
A: switch device, B: electric equipment, 1: switch body, 2, 21, 31 ... flexible printed circuit board (wiring base), 7: board main body (base body), 8: wiring, 9: connection terminal, 9a: base end portion, 9c: electric contact area, 10: protective layer, 11, 22, 32 ... coating film, 33: connector terminal, 34: opening.

Claims (8)

A plurality of wirings are formed on a base body made of the first polymer resin synthesized by dehydration condensation, and connection terminals of the plurality of wirings are formed on at least a part of the base body in an exposed state. A wiring substrate, wherein a coating film made of a second polymer resin is formed at least on the substrate body and between the plurality of connection terminals. A plurality of wirings are formed on a base body made of the first polymer resin synthesized by dehydration condensation, and connection terminals of the plurality of wirings are formed on at least a part of the base body in an exposed state. A wiring substrate, characterized in that these connection terminals are covered with a coating film made of a second polymer resin except for a region that is in electrical contact with the outside. The wiring substrate according to claim 1, wherein the first polymer resin is made of a flexible polymer resin. The wiring substrate according to claim 3, wherein the flexible polymer resin is made of any one of polyethylene terephthalate, polyimide, phenol resin, and polyethylene naphthalate. The wiring substrate according to any one of claims 1 to 4, wherein the second polymer resin is made of an addition polymerization type polymer resin. 6. The wiring substrate according to claim 5, wherein the addition polymerization type polymer resin is made of any one of a thermoplastic resin, a thermosetting resin, and an optical / electron beam curable resin. An electric device comprising the wiring base material according to claim 1. A switch device comprising the wiring base material according to claim 1.

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