JP2008235046A - Electronic device and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To address a problem of the prior art having difficulty to make corrosion proofing of a metal contact or the like due to isolation, and to achieve corrosion proofing and electrical conductivity of a metal contact or the like of an electronic device simultaneously by using a novel photocatalyst having also excellent electrical conductivity. <P>SOLUTION: An electronic component has an ITO thin film 3, for example, consisting of at least one kind selected from a group of ITO, IZO and AZO, and a plug 2 as a metal conductive section for conducting, e.g., transmission an electrical signal. The ITO thin film 3 is joined with the plug 2, and the electronic component comprises the plug 2 at least a part thereof is configured to allow light 5 of a wavelength λ≤380 nm to be incident thereupon. An electronic device 20 is provided with wirings 12A, 12B covered with ITO thin films 13A, 13B and so on. Excited electrons are generated in the ITO thin film 3 by radiation of light of a short wavelength of λ≤380 nm, and they flow into a plug metal to reduce the metal and drop its potential, so that corrosion of a surface of the metal is sufficiently prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic component such as a conductive plug or a connector that transmits and receives an electrical signal, and an electronic device having the same.

  There are many metal parts in electronic devices such as mobile phones, PDAs (personal digital assistants), digital cameras, stationary TVs (television receivers), and PCs (personal computers). One is a connector for exchanging electrical signals with another device, a power source, or an external medium (memory card or the like), and other examples include a metal conductive portion such as a wiring formed on a mounting board.

  Metals having good conductivity are mainly used for these, but copper, brass, aluminum, stainless steel, nickel and the like are used in consideration of cost. However, these are often plated with a corrosion resistant metal such as gold, silver or palladium. The reason is that corrosion and migration usually occur when a metal is exposed to a corrosive substance (for example, sulfur or a sulfur-containing compound) or moisture.

  The most commonly used method in metal anticorrosion technology is to form an organic thin film on the surface and physically block contact between corrosive substances and metal. For example, in Patent Document 1 described later, an anticorrosion method is proposed by depositing a room temperature curable silicone rubber on the surface of a metal conductive portion.

  On the other hand, large structures (ships, bridge girders, etc.) are often immersed in seawater or fresh water, and countermeasures against corrosion are more pressing issues than electronic devices. For example, a measure called a sacrificial electrode, in which a metal (such as zinc) having an electrochemically basic potential is brought into contact with the metal and the potential of the metal to avoid corrosion is kept below the corrosion potential, has been taken.

In addition, a technique called photocathode protection that achieves the same effect with a photocatalyst has also been proposed. For example, Non-Patent Document 1 described later shows an example in which SUS-304 is anticorrosive with a TiO ₂ coating.

JP 2004-149611 A (claims, paragraph numbers [0005] to [0028]) OHKO Y et al., J Electrochem Soc VOL.148 NO.1 (2001) B24-27

  However, as shown in the above-mentioned Patent Document 1, it is difficult to obtain high conductivity with an organic coating, and it is difficult to apply it to places where low resistance is required, such as metal contacts.

  In addition, when the above-described other technology is applied to an electronic device, the sacrificial electrode method has a risk that a product due to metal corrosion diffuses into the device and causes a failure. Even in the photo-corrosion protection method disclosed in Non-Patent Document 1, since the photocatalyst used is an insulator, it cannot be used in places that require electrical conductivity, such as metal contacts of electronic devices.

  The object of the present invention is to use a novel photocatalyst excellent in conductivity at the same time as the anticorrosion as compared with the above-mentioned conventional photocatalyst which is difficult to prevent the corrosion of metal contacts and the like due to the insulating property. The object is to make it possible to sufficiently achieve both corrosion resistance and electrical conductivity of contacts and the like.

  That is, the present invention provides at least one thin film selected from the group consisting of ITO (Indium-Tin-Oxide), IZO (Indium-Zinc-Oxide), and AZO (Aluminum-Zinc-Oxide), and an electrical signal. An electronic device having a metal conductive portion for performing transmission and the like, and the thin film is joined or connected to the metal conductive portion and at least a part of which is configured to allow light incidence It is concerned.

  The present invention further includes a thin film made of at least one selected from the group consisting of ITO, IZO, and AZO, and a metal conductive portion for transmitting electric signals, etc. The present invention also provides an electronic component such as a metal plug that is joined to the portion and at least a part of which is configured to allow light incidence.

The present inventor uses ITO, IZO, and AZO, which have been used as transparent conductive oxides (TCO), instead of conventional photocatalysts such as TiO ₂ and SrTiO ₃ , and has a function as a photocatalyst. Based on this finding, the above problems have been solved and the present invention has been achieved by joining (contacting) or connecting these oxides to metal parts that are susceptible to corrosion of electronic equipment. .

That is, TCO including ITO, IZO, and AZO (hereinafter sometimes referred to as ITO) has not been known to have a photocatalytic function until now, but has a short wavelength region shorter than the wavelength of near-ultraviolet light ( λ ≦ 380 nm) and is considered to be an oxide semiconductor having a forbidden band width (E _b : band gap) between the valence band and the conduction band of around 3.3 eV. It has been demonstrated for the first time by the present inventor that an electron is excited by irradiation with light having a wavelength of less than or equal to or less than this wavelength, and the effect of lowering the potential of the metal in contact or connection is shown. Moreover, ITO or the like has an advantage that the conductivity is as high as 10 ⁻⁵ Ωcm (specific resistance), and it is difficult to increase the contact resistance even if the metal surface is coated.

  As described above, TCO such as ITO exhibits an action of reducing the metal by exciting the electrons by absorbing light when irradiated with light having an energy higher than the band gap as an oxide semiconductor. The potential can be lowered below the corrosion potential, the anticorrosive action of the metal can be enhanced, and since it has high conductivity, it can be applied to metal conductive parts such as metal contacts.

  In the present invention, in order to realize the above-described effects sufficiently, the thin film made of ITO, IZO or AZO (hereinafter, these may be referred to as TCO of the present invention) is used for the wavelength of near-ultraviolet light. In the following, it is desirable to exhibit semiconductor characteristics that sufficiently absorb short wavelength light in a short wavelength region of λ ≦ 380 nm. Here, both TCOs of the present invention have sufficient conductivity, but ITO and IZO have equivalent conductivity, IZO has good surface properties when made into a thin film, and AZO has low cost. There are benefits.

  The metal conductive portion is a metal contact portion or a metal wiring portion to which the thin film is bonded, or a metal wiring portion inside the electronic device connected to the thin film provided on the outer surface of the casing of the electronic device by a lead wire. The material may be copper, nickel or the like. Specifically, the metal contact portion forms a conductive plug or connector.

  The thin film may be bonded to the surface of the metal conductive portion at least in the light incident area. In addition, the thin film disposed in the light incident area is connected to the metal conductive portion via a lead wire. It may be.

  The thin film may be present as a single film of ITO, IZO or AZO or a laminated film of each single material, or a single powder or mixture of ITO, IZO or AZO may be applied. It may be attached by, for example.

  The TCO of the present invention such as ITO may be formed into a thin film by a general-purpose thin film forming technique such as spraying, sputtering, CVD (Chemical Vapor Deposition), laser ablation, or the TCO powder of the present invention is formed. The ink may be kneaded into an insulating resin or the like and applied. The resin that can be used here may be a general-purpose epoxy resin, a transparent polyimide, or the like, as long as the light absorption at λ ≦ 380 nm is not 100%.

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

Example 1
FIG. 1A schematically illustrates an example in which the TCO of the present invention is applied to a metal contact 1. According to this, on the surface of a metal plug such as copper or nickel or the surface of the main body (male) 2, for example, an ITO thin film 3 which is one kind of TCO of the present invention is deposited (bonded) by a sputtering method or the like. is important.

  That is, when the metal plug 2 is used detachably with respect to the metal plug (female) 4 on the cabinet side of the electronic device 10, the metal M on the surface of the metal plug 2 as shown in FIG. Is subjected to a reduction action based on the photocatalytic action of the ITO thin film 3 that is manifested by irradiation with light 5 having a short wavelength of λ ≦ 380 nm (this is included in normal indoor lighting, sunlight, etc.). Corrosion of the surface of the metal plug 2 is sufficiently prevented. It is advantageous that this effect can be obtained even with the metal plug 2 inserted.

This phenomenon (photocatalytic ability or photoprotective ability) will be described with reference to FIG. TCO made of ITO, IZO or AZO has not been recognized so far to show a photocatalytic function, but has absorption in a short wavelength region (λ ≦ 380 nm) below the wavelength of near-ultraviolet light. B. And conduction band C.I. B. It is considered that this is an oxide semiconductor whose forbidden band width ( _Eb : bandgap) between and is in the vicinity of 3.3 eV. For example, in ITO, as shown in FIG. 2 (a), electrons are excited by irradiation with light 5 having a wavelength of near ultraviolet light or less, and ΔV = 0.028V (this is (Measured with a platinum plate as a counter electrode in a corrosive solution of NaCl aqueous solution) and the potential is lowered, and this has the effect of lowering the potential of the contacting metal M (here, the metal plug body 2). This was demonstrated for the first time by the present inventors.

To explain this in more detail, metal corrosion is an electrochemical process, and the electrons at the anode (eg Cu → Cu ²⁺ + 2e), cathode (1 / 2O ₂ + H ₂ O + 2e → 2OH ⁻ or 2H ⁺ + 2e → H ₂ ) A transfer reaction is involved. Here, as shown in FIG. 2B, when the ITO 3 is irradiated with light 5 having energy higher than the band gap, the light is absorbed and the electrons are excited, and the excited electrons e are converted into the conduction band. C. B. When flowing from 1 to metal 2, the potential of metal 2 shifts to the flat band side having a lower potential (the metal undergoes a reducing action). Since this band position is lower than the oxidation potential (corrosion potential) of the metal, the oxidation can be suppressed, and as a result, the corrosion protection of the metal can be realized.

Moreover, since the conductivity of ITO3 is as high as 10 ⁻⁵ Ωcm (specific resistance), even if the surface of the metal 2 is coated, the contact resistance is not increased, and the conductivity is sufficiently ensured. be able to.

Example 2
FIG. 3 schematically shows an example in which the TCO of the present invention is applied to an electronic device called a so-called memory stick.

  This electronic device 20 has external terminals 12a, 12b... Connected to a personal computer among wirings 12A, 12B... Connected to an IC (integrated circuit) unit 15 such as a control circuit. Are coated with, for example, ITO thin films 13A, 13B... As TCO, and each wiring is led to the externally exposed end surface 16 on the side opposite to the external terminals, and each is mounted on a personal computer. Each ITO thin film is configured to be exposed to the outside at the wiring end face.

  Accordingly, when the electronic device 20 is used, light having a short wavelength of λ ≦ 380 nm is applied to the ITO thin films 13A, 13B... Exposed on the end face 16 (this is included in normal indoor lighting, sunlight, and the like). Excited electrons are generated in the ITO thin film by irradiation of this, and this flows into the metal wirings 12A, 12B... Including the external terminal side to reduce the constituent metals of these metal wirings and lower their potential. Surface corrosion is sufficiently prevented. In other respects, the same effects as described in Example 1 can be obtained.

  As a modification of this example, the above metal wiring is not provided to the end face 16 but is provided in a normal wiring area, while only the above ITO thin film is provided to the end face 16 or the ITO thin film is provided as a metal wiring. May be provided only on the external terminals 12a, 12b. In the above case, corrosion of the metal wiring can be prevented by the same mechanism as described above, and in the latter case, even if the metal wiring is corroded during use, the area of the ITO thin film is removed after being removed from the personal computer. By irradiating light with λ ≦ 380 nm, the oxidation state of the metal wiring can be reduced and changed to the original metal by the photocatalytic action (reduction action by excited electrons) of the ITO thin film, and the corrosion state can be removed. .

Example 3
FIG. 4 schematically shows an example in which the TCO of the present invention is applied to a general metal wiring in the electronic device 30.

  That is, predetermined portions of the metal wirings 22A, 22B, etc., such as copper, for example, the extended end portions 22a, 22b,... Are covered with, for example, the ITO thin films 23A, 23B,. It is configured as follows. For this purpose, the ITO thin film region may be structured to allow external light to enter or to be exposed to the outside.

  In this example as well, even if the metal wiring is likely to be corroded during use, the metal thin film is photocatalyzed (reduction action by excited electrons) of the ITO thin film by irradiating the above-mentioned ITO thin film region with light of λ ≦ 380 nm. Corrosion of can be prevented. In other respects, the same effects as described in Example 1 are obtained.

Example 4
FIG. 5 schematically shows still another example to which the TCO of the present invention is applied.

  That is, as shown in FIG. 5A, for example, an ITO thin film 33 is formed as a TCO by coating on the outer surface of the external housing (cabinet) 30 of the electronic device 40, and this is formed in the built-in circuit portion 37 via the lead wire 36. The contact metal 32 is electrically connected. The contact metal 32 may be a part of the metal wiring 42 connected to the outer lead 39 of the IC chip 38 as an electronic component. However, the connection form of the lead wire 36 may take various forms depending on the type of electronic component, and may be connected to the ground wiring or the like of the built-in circuit unit. The ITO thin film 33 can be formed by applying an ink obtained by kneading ITO powder in an epoxy resin or the like.

  In this example, even if the metal wiring (including the outer lead 39) of the built-in circuit portion 37 is corroded during use, the region of the ITO thin film 33 exposed on the outer surface of the housing 30 satisfies λ ≦ 380 nm. By irradiating the light 5, as shown in FIG. 5B, excited electrons are generated in the ITO thin film 30 and flow into the metal wirings 42 and 39 through the lead 35 to reduce the oxidation state, thereby reducing the original metal. The corrosion state can be removed.

  Next, the present invention will be described more specifically with reference to examples.

Comparative Example 1
The surface of the copper laminated substrate for evaluation (surface area 4 cm ² ) was chemically polished and put into a 100 ml aqueous solution of 0.1N NaCl as a corrosive agent. In order to promote corrosion, the samples were left exposed to the atmosphere for experiments. This is because oxygen is easily dissolved in the solution. The environmental temperature was 25 ° C to 27 ° C.

The corrosion was evaluated by taking out a sample after 72 h (3 days), and measuring the coloring due to corrosion (green) and the dry weight (the increase in dry weight after corrosion based on the weight before corrosion). Irradiation light was generated by a xenon lamp (manufactured by Ushio Inc.) that emits a wide range of light from 200 nm to 500 nm (including λ ≦ 380 nm), imitating natural light, and continuously irradiated at an illuminance of 10 mW / cm ² .

Example 1
An ITO thin film was formed on a copper laminated substrate (surface area 4 cm ² ) according to Comparative Example 1. This film was formed using a high frequency sputtering method to a film thickness of 10 nm. The specific resistance of ITO was about 2 × 10 ⁻⁵ Ωcm. Corrosion was evaluated in the same manner as in Comparative Example 1.

Example 2
In addition to the ITO film-forming area being halved (2 cm ² ), samples were prepared in accordance with Example 1 and evaluated for corrosion.

Example 3
A sample was prepared in accordance with Example 1 and corrosion was evaluated except that ITO was changed to IZO having the same thickness.

Example 4
A sample was prepared in accordance with Example 1 and corrosion was evaluated except that ITO was changed to AZO having the same thickness. The specific resistance of AZO was about 5 times (10 ⁻⁴ Ωcm) that of ITO.

  The results obtained in each of the above examples are summarized in Table 1 below.

  According to this result, the copper pieces of Examples 1 to 4 in which three kinds of TCO of ITO, IZO or AZO were joined, respectively, have a lower weight increase rate than the copper piece of Comparative Example 1 in which TCO is not joined. Since there is no coloring, it has been found that an excellent anticorrosive effect is achieved. Since the weight increase rate allowable limit = 0.001%, the values in Examples 1, 3, and 4 were within the allowable range.

  As described above, the TCO of the present invention is an oxide semiconductor, and when irradiated with light having energy greater than or equal to the band gap, electrons are excited by light absorption and show a reducing action, which is the potential of the metal in contact. It was confirmed that the anticorrosive action of the metal was increased.

  As described above, the present invention has been variously illustrated with respect to the embodiments and examples. However, it goes without saying that these examples can be appropriately modified without departing from the gist of the present invention.

  For example, instead of the ITO thin film or the ITO coating film described above, an IZO or AZO thin film or a coating film may be formed, or these TCOs may be formed as a laminated film or a mixed powder.

  In addition to the above-described examples, these TCO thin films are applied to various electronic devices or electronic parts such as metal wiring, plugs, connectors, and grounding power lines for electric signal transmission or potential holding. can do.

  Further, the light incident on the TCO thin film may be light having a wavelength capable of exhibiting the optical semiconductor characteristics, and may be light having a short wavelength of λ ≦ 380 nm or light including this wavelength, particularly near-ultraviolet light. . The light may be room light or sunlight (natural light), but may be emitted from a lamp such as a xenon lamp, a mercury lamp, or a halogen lamp.

  It is possible to provide an electronic component such as a conductive plug or a connector that transmits and receives an electric signal that achieves both anti-corrosion properties and ensuring conductivity, and an electronic device having the electronic component.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a schematic cross-sectional view of an example of an electronic component and an electronic apparatus according to the present invention, and FIG. FIG. 4 is a characteristic diagram (a) showing the potential change of ITO by light irradiation and a band diagram (b) for explaining the photocatalytic ability (photocorrosion ability). It is the schematic plan view of the other example of the electronic device by this invention, its left view, and right view. It is the schematic plan view of the other example of the electronic device by this invention, and its right view. It is the schematic sectional drawing (a) of the other example of the electronic device by this invention, and its principal part sectional drawing (b).

Explanation of symbols

1 ... Metal contact, 2 ... Plug (male),
3, 13A, 13B, 23A, 23B, 33 ... ITO thin film, 4 ... plug (female), 5 ... light, 10, 20, 30, 40 ... electronic equipment, 12A, 12B, 22A, 22B, 42 ... wiring,
12a, 12b ... external terminals, 15 ... integrated circuit section, 16 ... exposed end face, 30 ... casing,
32 ... Contact metal, 35 ... Lead wire, 37 ... Built-in circuit part, 38 ... IC chip,
39 ... Outer lead

Claims (14)

  A thin film made of at least one selected from the group consisting of ITO (Indium-Tin-Oxide), IZO (Indium-Zinc-Oxide), and AZO (Aluminum-Zinc-Oxide), and for transmitting electrical signals, etc. An electronic device having a metal conductive portion, wherein the thin film is joined or connected to the metal conductive portion and at least a part thereof is configured to allow light incidence.   The electronic device according to claim 1, wherein the thin film exhibits semiconductor characteristics that sufficiently absorb short-wavelength light having a wavelength shorter than or equal to that of near-ultraviolet light.   The metal conductive part is a metal contact part or a metal wiring part to which the thin film is joined, or an internal metal wiring part connected to the thin film provided on the outer surface of the housing by a lead wire. Electronics.   The electronic device according to claim 3, wherein the metal contact portion forms a conductive plug or a connector.   The electronic device according to claim 1, wherein the thin film is bonded to a surface of the metal conductive portion at least in a light incident area.   The electronic device according to claim 1, wherein the thin film is composed of a single film of ITO, IZO, or AZO or a laminated film of each single film.   The electronic device according to claim 1, wherein the thin film is made of a powder alone or a mixture of ITO, IZO, or AZO.   A thin film made of at least one selected from the group consisting of ITO, IZO, and AZO, and a metal conductive portion for transmitting an electrical signal, and the thin film is bonded to the metal conductive portion In addition, at least a part of the electronic component is configured so that light can enter.   The electronic component according to claim 8, wherein the thin film exhibits semiconductor characteristics that sufficiently absorb short-wavelength light having a wavelength shorter than or equal to that of near-ultraviolet light.   The electronic component according to claim 8, wherein the metal conductive portion constitutes a metal contact portion where the thin film is joined.   The electronic component according to claim 10, wherein the metal contact portion forms a conductive plug or a connector.   The electronic component according to claim 8, wherein the thin film is bonded to the surface of the metal conductive portion at least in a light incident area.   The electronic component according to claim 8, wherein the thin film is composed of a single film of ITO, IZO or AZO or a laminated film of each single film.   The electronic component according to claim 8, wherein the thin film is made of a powder or a mixture of ITO, IZO, or AZO.

Images