JP2006128228A - Forming method of conductive film, wiring board, electronic device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a conductive film which is excellent in conductivity and adhesion to a substrate, and capable of forming a thicker film, a wiring board comprising the conductive film formed by the method thereof, and a highly reliable electronic device and electronic equipment. <P>SOLUTION: In the method of forming a conductive film, the conductive film 3 of a specified pattern is formed on a substrate 2. A metal film 31 containing metal particles 31a is so formed on the substrate 2 by a droplet discharge method as to be the pattern similar to that of the conductive film 3. Then, by performing electroless plating by at least once, a plating film 32 is so formed as to cover the surface of the metal film 31, resulting in providing the conductive film 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a conductive film, a wiring board, an electronic device, and an electronic apparatus.

As a method for forming a wiring (conductive film), for example, a method using an electroless plating method (for example, see Patent Document 1), a method using metal particles (for example, see Patent Document 2), and the like are known. .
However, when the wiring is formed on the substrate by the electroless plating method, the adhesion between the wiring and the substrate is low, and the plating film by the electroless plating method has high film stress. For this reason, when wiring is formed with a thick film, there exists a problem that it will peel easily from a board | substrate.

In addition, since the adhesiveness is low, there is a problem that a wiring having a quality sufficient for reliability cannot be obtained.
On the other hand, when the wiring is formed with metal particles, the metal particles are supplied onto the substrate as ink droplets, so there is a limit to the content of metal particles in the ink droplets and drawing accuracy. For this reason, there is a problem that gaps are easily formed between metal particles, and cracks and disconnections are liable to occur if a relatively large area is formed.
In general, the ink droplet contains a binder for fixing the metal particles, so that there is a problem that it is difficult to obtain a low-resistance wiring.

JP 7-131135 A JP 2003-315813 A

  An object of the present invention is to provide a method for forming a conductive film that is excellent in conductivity and adhesion to the substrate and can be made thick, a wiring substrate having a conductive film formed by the method for forming such a conductive film, and high reliability To provide an electronic device and an electronic apparatus.

Such an object is achieved by the present invention described below.
The conductive film forming method of the present invention is a conductive film forming method for forming a conductive film having a predetermined pattern on a substrate,
On the substrate, a metal film containing metal particles is formed by a droplet discharge method so as to be a pattern substantially equal to the pattern of the conductive film,
Thereafter, electroless plating is performed at least once to form a plating film so as to cover the surface of the metal film, thereby obtaining the conductive film.
Thereby, it is excellent in electroconductivity and adhesiveness with a board | substrate, and a thick film electrically conductive film is obtained.

In the method for forming a conductive film of the present invention, the average thickness of the metal film is preferably 1 to 10 μm.
Thereby, for example, even when the metal film contains a binder, it is possible to sufficiently function as a core of the plating film while preventing a decrease in conductivity of the obtained conductive film.
In the method for forming a conductive film of the present invention, it is preferable that the metal particles are composed mainly of at least one of gold, silver, copper, nickel, palladium, or an alloy containing these.
Thereby, since these metal particles are especially excellent in electroconductivity, the electroconductivity improvement as the whole obtained electrically conductive film can be aimed at.

In the method for forming a conductive film of the present invention, it is preferable to selectively apply a catalyst to the surface of the metal film prior to performing the electroless plating.
Thereby, a plating film can be formed more efficiently.
In the method for forming a conductive film of the present invention, the electroless plating is performed a plurality of times,
Prior to performing the electroless plating each time after the second time, it is preferable to selectively apply a catalyst to the surface of the film formed in the previous time.
Thereby, a plating film can be formed more efficiently.
In the method for forming a conductive film of the present invention, the catalyst is preferably composed mainly of at least one of palladium, platinum, rhodium, iridium, tin, or an alloy containing these.
These catalysts are preferable because they have particularly high catalytic action.

In the method for forming a conductive film of the present invention, the electroless plating is performed a plurality of times,
In each electroless plating, it is preferable to use the same type of electroless plating solution.
Thereby, a conductive film with good adhesion can be obtained.
In the method for forming a conductive film of the present invention, the electroless plating is performed a plurality of times,
It is preferable to use an electroless plating solution different from the other times in at least one of the plurality of times of the electroless plating.
Thereby, the electrically conductive film excellent in performance is obtained.

In the method for forming a conductive film of the present invention, it is preferable that the plating film is composed mainly of at least one of nickel, copper, gold, and silver.
Thereby, the electrically conductive film excellent in performance is obtained.
In the method for forming a conductive film of the present invention, the average thickness of the film formed by the first electroless plating is preferably 100 to 1000 nm.
Thereby, it is possible to prevent the metal film from being easily peeled from the substrate while suppressing an increase in stress, and a conductive film having good adhesion can be obtained.

In the method for forming a conductive film of the present invention, the average thickness of the plating film is preferably 1 to 10 μm.
As a result, a conductive film having sufficient film strength and high conductivity can be obtained.
In the method for forming a conductive film of the present invention, it is preferable to form a base layer of the metal film on the substrate prior to forming the metal film.
The underlayer can be provided for various purposes.

In the method for forming a conductive film of the present invention, it is preferable that the base layer has a function of improving adhesion between the metal film and the substrate.
Thereby, the adhesiveness with respect to the board | substrate of an electrically conductive film improves more, and can peel more reliably from a board | substrate.
In the method for forming a conductive film of the present invention, the base layer preferably has an insulating property.
Thereby, even when the conductive film is formed with a high wiring density, it is possible to prevent a short circuit from occurring between the conductive films. Further, a metal substrate can be used, and there is an advantage that the range of substrate selection is widened.
In the method for forming a conductive film of the present invention, the substrate is preferably made of a nonmetal.
While using electroless plating, a conductive film can be formed on a nonmetallic substrate with good adhesion.

The wiring board of the present invention includes a substrate,
And a conductive film formed by the method for forming a conductive film of the present invention over the substrate.
Thereby, a highly reliable wiring board is obtained.
The wiring board of the present invention includes a substrate,
A conductive film including a metal film containing a metal particle provided in a predetermined pattern and a plating film provided to cover the surface of the metal film is provided over the substrate.
Thereby, a highly reliable wiring board is obtained.
An electronic device according to the present invention includes the wiring board according to the present invention.
Thereby, an electronic device with high reliability can be obtained.
An electronic apparatus according to the present invention includes the electronic device according to the present invention.
Thereby, a highly reliable electronic device can be obtained.

Hereinafter, the conductive film forming method, the wiring board, the electronic device, and the electronic apparatus according to preferred embodiments of the present invention will be described in detail.
<Method for Forming Conductive Film>
First, the formation method of the electrically conductive film of this invention is demonstrated.
FIG. 1 is a partial cross-sectional perspective view showing an example of the wiring board of the present invention.
As shown in FIG. 1, the conductive film forming method of the present invention is provided in a predetermined pattern, and a metal film 31 containing metal particles 31a and a plating film provided so as to cover the surface of the metal film 31. 32 is formed.

<< First Embodiment >>
First, a first embodiment of the method for forming a conductive film of the present invention will be described.
FIG. 2 is a diagram (longitudinal sectional view) showing a first embodiment of the method for forming a conductive film of the present invention. In the following description, the upper side in FIG. 2 is referred to as “upper” and the lower side is referred to as “lower”.
The conductive film forming method shown in FIG. 2 includes a metal film forming step [1A] and a plating film forming step [2A].

Hereinafter, each process will be described sequentially.
First, as shown in FIG. 2A, a substrate 2 on which a conductive film 3 is to be formed is prepared.
As the substrate 2, for example, various substrates such as a Si wafer, a quartz glass substrate, a glass substrate, a non-metallic substrate such as a plastic film, and a metallic substrate can be used. Alternatively, a substrate in which a semiconductor film, a metal film, a dielectric film, an organic film, or the like is formed on the surface thereof may be used as a substrate.
Among these, the substrate 2 is preferably a non-metallic substrate. According to the method for forming a conductive film of the present invention, the conductive film 3 can be formed on the nonmetallic substrate 2 with good adhesion while using electroless plating as described later.

[1A] Metal Film Formation Step First, as shown in FIG. 2B, a metal film formation material 310 containing metal particles 31a is discharged onto the substrate 2 by a droplet discharge method such as an inkjet method. Then, a metal film 31 as shown in FIG. 2C is formed.
At this time, the metal film 31 is formed so as to have a pattern substantially equal to the pattern of the target conductive film 3. By using the droplet discharge method, the metal film 31 can be easily and accurately patterned without using a resist layer (mask).
The metal film 31 functions as a core (core part) for growing a plating film 32 described later, and also functions as a bonding layer for bonding the substrate 2 and the plating film 32.

The metal particles 31a may be made of silver, gold, copper, nickel, palladium, platinum or an alloy containing these, and in particular, gold, silver, copper, nickel, palladium or an alloy containing these. It is preferable to use a material composed of at least one of them as a main material. Since these metal particles 31a are particularly excellent in conductivity, the conductivity of the obtained conductive film 3 as a whole can be improved.
These metal particles 31a may be used after being coated with, for example, an organic substance in order to improve dispersibility in the metal film forming material 310.

  The average particle diameter of the metal particles 31a is not particularly limited, but is preferably about 1 to 100 nm, and more preferably about 1 to 50 nm. If the particle size of the metal particles 31a is too small, the metal particles 31a are likely to aggregate and the dispersibility in the metal film forming material 310 may be reduced. On the other hand, if the particle size of the metal particles 31a is too large, the nozzles of the droplet discharge head may be clogged.

  The dispersion medium used for adjusting the metal film forming material 310 (dispersing the metal particles 31a) preferably has a vapor pressure of about 0.001 to 200 mmHg (about 0.133 to 26600 Pa) at room temperature. More preferably, it is about 001-50 mmHg (about 0.133-6650 Pa). If the vapor pressure of the dispersion medium is too low, evaporation of the dispersion medium becomes insufficient, and the dispersion medium tends to remain in the metal film 31, which is not preferable. On the other hand, if the vapor pressure of the dispersion medium is too high, after the metal film forming material 310 is discharged onto the substrate 2, the dispersion medium rapidly evaporates and it may be difficult to form a good metal film 31. is there. Further, when the metal film forming material 310 is ejected as droplets by the droplet ejection method, nozzle clogging due to drying tends to occur, and stable droplet ejection may be difficult.

  Such a dispersion medium is not particularly limited, but in addition to water, for example, alcohols such as methanol, ethanol, propanol and butanol, n-heptane, n-octane, decane, tetradecane, toluene, xylene, and cymene. , Hydrocarbons such as durene, indene, dipentene, tetrahydronaphthalene, decahydronaphthalene, cyclohexylbenzene, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, ethers such as p-dioxane, propylene Carbonate, .gamma.-butyrolactone, N- methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, and cyclohexanone.

Among these, as the dispersion medium, water, alcohols, hydrocarbons, and ethers are preferable, and water and hydrocarbons are more preferable. These dispersion media have the advantage that the metal particles 31a are easily dispersed uniformly, the storage stability of the adjusted metal film forming material 310 is high, and the droplet ejection method is easy to apply.
In addition, the dispersion medium as described above can be used alone or in admixture of two or more kinds.

  In addition, the content (dispersoid concentration) of the metal particles 31a in the metal film forming material 310 may be appropriately adjusted according to the film thickness of the target metal film 31 and the like, and is not particularly limited. It is preferably about ˜80 wt%. More preferably, it is about 10-60 wt%. If the content of the metal particles 31a is increased beyond the upper limit, the metal particles 31a are likely to aggregate together, and it may be difficult to obtain the metal film 31 having a uniform film thickness.

  The surface tension of the metal film forming material 310 is preferably about 0.02 to 0.07 N / m, and more preferably about 0.02 to 0.05 N / m. When discharging the metal film forming material 310 by the droplet discharge method, if the surface tension is too low, the wettability of the metal film forming material 310 with respect to the nozzle surface may increase and flight bending may easily occur. If the surface tension is too high, the shape of the meniscus at the nozzle tip is not stable, and it may be difficult to control the discharge amount and the discharge timing.

In order to adjust the surface tension, a small amount of a surface tension regulator such as fluorine, silicone or nonion is added to the metal film forming material 310 within a range where the contact angle with the substrate 2 is not lowered more than necessary. May be. For example, the nonionic surface tension adjusting agent improves the wettability of the metal film forming material 310 to the substrate 2, improves the leveling property of the formed metal film 31, and generates fine irregularities on the metal film 31. Is preferably prevented.
Further, the metal film forming material 310 may contain an organic compound such as alcohol, ether, ester, or ketone, if necessary.

  The viscosity of the metal film forming material 310 is preferably about 1 to 50 mPa · s, and more preferably about 5 to 30 mPa · s. When discharging the metal film forming material 310 by the droplet discharge method, if the viscosity is too low, the peripheral portion of the nozzle may be easily contaminated by the outflow of the metal film forming material 310, whereas if the viscosity is too high, There is a possibility that clogging frequency in the nozzle hole is increased, and it is difficult to smoothly discharge the metal film forming material 310.

The metal film forming material 310 supplied in a predetermined pattern on the substrate 2 may be subjected to, for example, heat treatment or the like to form the metal film 31 as necessary. Thereby, when the metal film 31 contains a binder, the binder can be removed from the vicinity of the surface of the metal film 31 to expose the metal particles 31a.
Although the average thickness of the metal film 31 to be formed is not particularly limited, it is preferably about 1 to 10 μm, and more preferably about 1 to 5 μm. If the thickness of the metal film 31 is too thin, the metal film 31 may not function sufficiently as a core of the plating film 32 to be described later. On the other hand, if the metal film 31 is thicker than the upper limit value, for example, the metal film 31 may contain a binder. When contained, depending on the type and amount of the binder, the conductivity of the obtained conductive film 3 may be extremely reduced.

[2A] Plating Film Formation Step Next, the plating film 32 is formed so as to cover the surface of the metal film 31 by performing electroless plating at least once (in this embodiment, four times). Thereby, the conductive film 3 is obtained.
First, as shown in FIG. 2 (d), the catalyst 5 is selectively applied to the surface of the metal film 31. Thereby, the 1st film | membrane 321 (plating film | membrane 32) can be formed more efficiently.

This is performed by supplying (contacting) a catalyst-providing liquid containing the catalyst 5 to the surface of the metal film 31.
As a method for supplying the catalyst-providing liquid to the surface of the metal film 31, for example, a dip coating method, a spin coating method, a slit coating method, a cap coating method, a dispenser method, a spray coating method, a roll coating method, an ink jet method (droplet) Various application methods such as a discharge method) can be mentioned, and one of these or any two or more of them can be used in combination.

  Examples of the catalyst include palladium, platinum, rhodium, iridium, a tin-palladium mixed solution or an alloy containing these, and among these, palladium, platinum, a tin-palladium mixed solution, or an alloy containing these. Those having at least one of them as a main material are suitable. These catalysts 5 are preferable because they have particularly high catalytic action.

The catalyst-providing liquid can be adjusted, for example, by dissolving the catalyst salt (halide or the like) in a solvent.
When such a catalyst-providing liquid is brought into contact with the surface of the metal film 31, the catalyst 5 is deposited as a single metal on the surface of the metal particles 31a.
For this reason, it is preferable to perform an activation treatment on the surface of the metal film 31 prior to bringing the catalyst applying liquid into contact with the surface of the metal film 31. As this activation process, the process (light etching) which removes the coating agent, oxide film, etc. on the surface of the metal particle 31a is mentioned, for example. Thereby, a catalyst can be more reliably deposited (attached) on the surface of the metal particle 31a.

The removal amount of the surface of the metal particles 31a by this light etching can be prepared (controlled) by setting the concentration of the etching solution, the etching time, and the like.
In addition, the conditions for applying the catalyst to the surface of the metal film 31, for example, the salt concentration in the catalyst application liquid, the temperature of the catalyst application liquid, the contact time of the catalyst application liquid to the surface of the metal film 31, respectively, There is no particular limitation.
In addition, when the metal particle 31a in the metal film 31 has a catalytic action, the catalyst provision to the surface of the metal film 31 can be omitted.

Next, the first electroless plating is performed by immersing the substrate 2 on which the metal film 31 is formed in the electroless plating solution. As a result, as shown in FIG. 2E, a first film 321 is formed on the surface of the metal film 31 with the catalyst 5 as a nucleus.
Here, the average thickness of the first film 321 is not particularly limited, but is preferably about 100 to 1000 nm, and more preferably about 150 to 800 nm. If the first film 321 is less than the lower limit value, the metal film may be island-like and not sufficiently formed into a film, and as a result, the film quality may be uneven. If the thickness of the film 321 exceeds the upper limit, the metal film 31 may be easily peeled off from the substrate 2.
The film thickness of the first film 321 is prepared by appropriately setting, for example, the concentration of the metal salt in the electroless plating solution, the temperature of the electroless plating solution, the immersion time of the substrate 2 in the electroless plating solution, and the like. (Control).

Next, after applying a catalyst to the surface of the first film 321 in the same manner as described above, the substrate 2 is immersed in the electroless plating solution (performing the second electroless plating), so that FIG. As shown in f), a second film 322 is formed.
In this way, the electroless plating is repeatedly performed, and the third film 323 and the fourth film 324 are sequentially formed as shown in FIG. Thereby, the plating film 32 is obtained.
In this way, by forming the plating film 32 by a plurality of times of electroless plating, it is possible to reliably obtain a film having a large film thickness while maintaining the adhesion with the metal film 31.

In this case, the thickness of the film formed by each electroless plating may be substantially equal, but it is preferable to increase the thickness of the film formed in the subsequent round so as to be different. . Thereby, the conductive film 3 having higher adhesion to the substrate 2 can be obtained.
In this case, the same type of electroless plating solution used each time may be used, or a different type of electroless plating solution may be used at least once.

When the same type of electroless plating solution is used, there is an advantage that, for example, it is not necessary to consider the compatibility of the metal film itself, and the adhesion is good.
On the other hand, when a different type of electroless plating solution is used at least once, there are the following advantages.
That is, I: For example, by using an electroless gold plating solution as the last electroless plating solution and forming the vicinity of the surface of the conductive film 3 with gold, the conductive film 3 can be protected, Connection with other wiring can be easily performed.

II: For example, by using a laminated film of nickel and gold or copper as the plating film 32, relatively inexpensive nickel is used while maintaining conductivity, so that cost reduction can be realized.
III: For example, by laminating films whose film stresses are opposite to each other, the film stress of the plating film 32 can be eliminated or alleviated, and peeling of the plating film 32 from the metal film 31 can be more reliably prevented. can do. Here, in general, examples of the film in which the film stress appears strongly in the compression direction include a nickel-phosphorous film, and examples of the film in which the film stress appears strongly in the tensile direction include a nickel-boron film and a copper film. It is done.
The number of times of electroless plating is not limited to four times, and may be performed once, twice, three times, or five times or more.

The average thickness of the plating film 32 is not particularly limited, but is preferably about 1 to 10 μm, and more preferably about 1 to 5 μm. Thereby, the conductive film 3 having sufficient film strength and high conductivity can be obtained.
In addition to the nickel, copper, and gold, examples of the constituent material of the plating film 32 include silver, and one or more of these may be used in combination (for example, stacked). Is preferred. These are excellent in that the conductivity as a conductive film is good.
The wiring board 1 of the present invention is obtained through the above steps.
Such a wiring substrate 1 is highly reliable because the conductive film 3 has high conductivity, is provided on the substrate 2 with high adhesion, and does not easily peel off.

<< Second Embodiment >>
Next, a second embodiment of the method for forming a conductive film of the present invention will be described.
FIG. 3 is a view (longitudinal sectional view) showing a second embodiment of the method for forming a conductive film of the present invention. In the following description, the upper side in FIG. 3 is referred to as “upper” and the lower side is referred to as “lower”.
Hereinafter, the method for forming a conductive film according to the second embodiment will be described with a focus on differences from the method for forming a conductive film according to the first embodiment, and description of similar matters will be omitted.
In the second embodiment, the base layer 4 is formed on the substrate 2 prior to the formation of the metal film 31, and the rest is the same as in the first embodiment.
The conductive film forming method shown in FIG. 3 includes a base layer forming step [1B], a metal film forming step [2B], and a plating film forming step [3B].

[1B] Underlayer Formation Step First, as shown in FIG. 3A, the underlayer 4 is formed on the substrate 2.
Here, the base layer 4 has a function of improving the adhesion between the metal film 31 and the substrate 2. By providing the base layer 4, the adhesion between the metal film 31 and the substrate 2 is improved. Therefore, even when the substrate 2 is flexible, the metal film 31 (conductive film 3) is the substrate 2. It can be reliably prevented from peeling off.

Moreover, it is preferable that this foundation layer 4 has insulation. Thereby, even when the conductive film 3 is formed with a high wiring density, it is possible to prevent a short circuit from occurring between the conductive films 3. Further, a metal substrate can be used as the substrate 2, and there is an advantage that the range of selection of the substrate 2 is widened.
Examples of the constituent material (insulating material) of the underlayer 4 include polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin, poly Vinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polyamideimide, polycarbonate, poly- (4-methylpentene-1), ionomer, acrylic resin, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer (ABS resin) ), Acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer, polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyethylene Polyester such as terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexane terephthalate (PCT), polyether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal (POM), polyphenylene Oxide, modified polyphenylene oxide, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin, polyvinyl chloride , Polyurethane, polyester, polyamide, polybutadiene, trans polyisoprene, fluororubber, chlorinated polyethylene Various thermoplastic elastomers such as epoxy resins, epoxy resins, urea resins, urea resins, melamine resins, unsaturated polyesters, silicone resins, polyurethanes, etc., or copolymers mainly containing these, blends, polymer alloys, etc. One or more of these can be used in combination (for example, as a laminate of two or more layers).

The average thickness of the underlayer 4 is not particularly limited, but is preferably about 1 to 25 μm, and more preferably about 5 to 20 μm. If the thickness of the underlayer 4 is too thin, sufficient adhesion between the substrate 2 and the metal film 31 may not be obtained or sufficient insulation may not be exhibited depending on the constituent material of the underlayer 4. There is a fear. On the other hand, even if the thickness of the underlayer 4 is increased beyond the upper limit, no further increase in effect can be expected, and if the substrate 2 has flexibility, the flexibility may decrease. is there.
Further, the underlayer 4 is formed by supplying an underlayer forming material in which such a material or a precursor thereof is dissolved or dispersed onto the substrate 2 and then, for example, drying, heat treatment, ultraviolet irradiation, or the like. Can do.

As a method for supplying the base layer forming material onto the substrate 2, various coating methods similar to those exemplified as the method for supplying the catalyst-imparting liquid can be used.
The underlayer 4 may be provided for the purpose other than the purpose of improving the adhesion between the substrate 2 and the metal film 31, and for the purpose of both the other purpose and the purpose of improving the adhesion. .
In the illustrated configuration, the underlayer 4 is formed on the entire surface of the substrate 2. However, the present invention is not limited to this. For example, the underlayer 4 may be formed in a pattern substantially equal to the conductive film 3.

[2B] Metal Film Forming Step The same as step [1A]. As a result, a metal film 31 is formed on the base layer 4 as shown in FIG.
[3B] Plating film forming step This is performed in the same manner as in the above step [2A]. As a result, the plating film 4 is formed so as to cover the surface of the metal film 31 as shown in FIG.
The wiring board 1 of the present invention is obtained through the above steps.
In the second embodiment, since the base layer 4 is provided, the adhesion of the conductive film 3 to the substrate 2 is further improved, and peeling from the substrate 2 can be more reliably prevented.

<Electronic device>
The wiring substrate 1 as described above can be applied to various semiconductor devices, electronic devices such as liquid crystal display devices, organic EL display devices, display devices such as plasma display devices, and the like.
Hereinafter, a case where the electronic device of the present invention is applied to a plasma display apparatus will be described as an example.

FIG. 4 is an exploded perspective view showing an embodiment in which the electronic device of the present invention is applied to a plasma display apparatus.
A plasma display device 500 shown in FIG. 4 is generally configured by a glass substrate 501 and a glass substrate 502 that are arranged to face each other, and a discharge display portion 510 formed between them.

The discharge display unit 510 includes a plurality of discharge chambers 516, and among the plurality of discharge chambers 516, three of the red discharge chamber 516 (R), the green discharge chamber 516 (G), and the blue discharge chamber 516 (B). Two discharge chambers 516 are arranged in pairs to constitute one pixel.
Address electrodes 511 are formed in stripes at predetermined intervals on the upper surface of the glass substrate 501, and a dielectric layer 519 is formed so as to cover these address electrodes 511 and the upper surface of the substrate 501.
Further, a partition wall 515 is formed on the dielectric layer 519 so as to be positioned between the address electrodes 511 and 511 and along each address electrode 511.

The partition 515 is also partitioned at a predetermined interval in a direction perpendicular to the address electrode 511 at a predetermined position in the longitudinal direction (not shown).
As a result, basically, rectangular regions partitioned by partition walls adjacent to both the left and right sides of the address electrode 511 in the width direction and partition walls extending in a direction perpendicular to the address electrodes 511 are formed. A discharge chamber 516 is formed so as to correspond to this region. One pixel is formed by three pairs of these rectangular regions.

  In addition, a phosphor layer 517 is provided inside a rectangular region partitioned by the partition 515. The phosphor layer 517 emits red, green, or blue fluorescence, and the red phosphor layer 517 (R) is disposed at the bottom of the red discharge chamber 516 (R). A green phosphor layer 517 (G) is provided at the bottom of G), and a blue phosphor layer 517 (B) is provided at the bottom of the blue discharge chamber 516 (B).

On the other hand, on the glass substrate 502 side, a plurality of transparent display electrodes 512 are formed in stripes at predetermined intervals in a direction orthogonal to the previous address electrodes 511. The transparent display electrode 512 is made of a transparent conductive material such as ITO, FTO, or ATO.
Further, a metal bus electrode 512 a is formed in contact with the transparent display electrode 512. The bus electrode 512a has a function of reducing the resistance value of the transparent display electrode 512.
Further, a dielectric layer 513 is formed so as to cover the transparent display electrode 512 and the bus electrode 512a, and a protective film 514 made of MgO or the like is further formed.

The glass substrate 501 and the glass substrate 502 are bonded to each other so that the address electrodes 511 and the transparent display electrodes 512 are opposed to each other so as to be orthogonal to each other, and a space portion surrounded by the phosphor layer 517 and the protective film 514 is formed. A discharge chamber 516 is formed by exhausting and sealing a rare gas.
Note that two transparent display electrodes 512 formed on the glass substrate 502 side are formed so as to be arranged two by two for each discharge chamber 516.

The address electrode 511 and the transparent display electrode 512 are connected to an AC power source (not shown), and when each electrode is energized, the phosphor layer 517 is excited to emit light in the discharge display unit 510 at a desired position, and color display is performed. It can be done.
In such a plasma display device 500, for example, the glass substrate 501 on which the address electrode 511 is formed is constituted by the wiring substrate of the present invention.

<Electronic equipment>
The electronic device of the present invention can be applied to various electronic devices.
<< personal computer >>
FIG. 5 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which the electronic apparatus of the present invention is applied.

In this figure, a personal computer 1100 includes a main body 1104 having a keyboard 1102 and a display unit 1106. The display unit 1106 is supported by the main body 1104 via a hinge structure so as to be rotatable. Yes.
In the personal computer 1100, the display unit 1106 includes the display device (electronic device) described above.

FIG. 6 is a perspective view showing a configuration of a mobile phone (including PHS) to which the electronic apparatus of the present invention is applied.
In this figure, a cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206, and the above-described display device (electronic device) in a display unit.

FIG. 7 is a perspective view showing the configuration of a digital still camera to which the electronic apparatus of the present invention is applied. In this figure, connection with an external device is also simply shown.
Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an imaging device such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

On the back of the case (body) 1302 of the digital still camera 1300, the above-described display device (electronic device) is provided in the display unit, and is configured to perform display based on an imaging signal from the CCD. Functions as a finder to display as
A circuit board 1308 is installed inside the case. The circuit board 1308 is provided with a memory that can store (store) an imaging signal.
A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side of the case 1302 (on the back side in the illustrated configuration).

When the photographer confirms the subject image displayed on the display unit and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory of the circuit board 1308.
In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the figure, a television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the data communication input / output terminal 1314 as necessary. Further, the imaging signal stored in the memory of the circuit board 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation.

  In addition to the personal computer (mobile personal computer) of FIG. 5, the mobile phone of FIG. 6, and the digital still camera of FIG. 7, the electronic apparatus of the present invention includes, for example, a television, a video camera, a viewfinder type, Monitor direct-view video tape recorder, laptop personal computer, car navigation system, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV Monitors, electronic binoculars, POS terminals, devices equipped with touch panels (for example, cash dispensers and automatic ticket vending machines for financial institutions), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiographs, ultrasound diagnostic devices, internal Endoscope display device), fish finder, various measuring instruments, Vessels such (e.g., gages for vehicles, aircraft, and ships), a flight simulator, various monitors, and a projection display such as a projector.

As described above, the method for forming a conductive film, the wiring board, the electronic device, and the electronic apparatus have been described based on the illustrated embodiments, but the present invention is not limited thereto.
For example, in the method for forming a conductive film of the present invention, one or two or more optional steps may be added.
In the electronic device and the electronic apparatus of the present invention, the configuration of each part can be replaced with any configuration that exhibits the same function, and any configuration can be added.

Next, specific examples of the present invention will be described.
1. Production of wiring board (Example 1)
First, as a metal film-forming material, a dispersion medium of a liquid (“Perfect Silver”, manufactured by Vacuum Metallurgical Co., Ltd.) in which silver particles having an average particle diameter of about 5 nm are dispersed in an organic solvent was replaced with tetradecane and adjusted.

The content of silver particles in the metal film forming material was 60 wt%, the viscosity of the metal film forming material was 8 mPa · s, and the surface tension was 0.05 N / m.
This metal film forming material is ejected in a pattern as shown in FIG. 1 on a glass substrate using a Seiko Epson ink jet printer head (a commercially available printer product name PM950C is remodeled to use an organic solvent-resistant head). did.

Next, the metal film forming material discharged on the glass substrate in a predetermined pattern was dried in the atmosphere at room temperature (25 ° C.) × 2 hours, and then fired in a nitrogen atmosphere at 400 ° C. × 1 hour.
The obtained metal film was a thin line part (average thickness: 3 μm, average width: 20 μm) and a pad part (average thickness: 3 μm, flat area: 0.15 mm ² ).
Next, light etching was performed on the metal film.

Next, the glass substrate on which the metal film was formed was immersed for 1 minute in a catalyst imparting solution containing a palladium salt (“Activator” manufactured by Meltex Co., Ltd.).
Thereby, palladium (catalyst) was provided to the surface of the metal film.
Next, this glass substrate was taken out from the catalyst application solution, washed with water, and then immersed in a nickel plating solution (Meltex, “electroless nickel plating solution”) for 2 minutes.
Thereby, nickel plating was performed on the metal film, and a nickel film having an average thickness of about 160 nm was formed so as to cover the surface of the metal film.

Next, after the glass substrate was washed with water, it was immersed in the same catalyst-imparting solution as described above for 2 minutes, and further washed with water and then immersed in the same nickel plating solution as described above for 3 minutes.
Next, this operation was repeated by changing the immersion time in the nickel plating solution to 3, 5, and 5 minutes.
Finally, substitution gold plating was performed. Thereby, a plating film was formed to obtain a conductive film.
The obtained conductive film had an average thickness of 8 μm (the average thickness of the plating film: 5 μm), and it was confirmed that the surfaces of the fine line portion and the pad portion were both dense.
Through the above steps, a wiring board was obtained.

(Example 2)
A polyimide film was used as a substrate, and a conductive film was formed on the polyimide film in the same manner as in Example 1 while being fixed to a glass substrate.
The electroless plating process is the same as in Example 1, but the number of nickel platings was three.
The immersion time in the nickel plating solution was set to 1 minute, 3 minutes, and 7 minutes.
The obtained conductive film had an average thickness of 6 μm (average thickness of the plating film: 3 μm), and it was confirmed that the surfaces of the fine wire portion and the pad portion were both dense.

(Example 3)
A wiring board was manufactured in the same manner as in Example 1 except that a base layer formed as shown below was provided.
An epoxy resin precursor was supplied onto a glass substrate by spin coating, and then baked at 280 ° C. for 1 hour. As a result, an underlayer having an average thickness of 5 μm was formed.
Example 4
A wiring board was manufactured in the same manner as in Example 2 except that a base layer was provided in the same manner as in Example 3.

(Comparative Example 1)
A wiring board was manufactured in the same manner as in Example 1 except that the metal film was omitted.
(Comparative Example 2)
A wiring board was manufactured in the same manner as in Example 2 except that the metal film was omitted.
(Comparative Example 3)
A wiring board was manufactured in the same manner as in Example 3 except that the metal film was omitted.
(Comparative Example 4)
A wiring board was manufactured in the same manner as in Example 4 except that the metal film was omitted.

2. Evaluation Each of the wiring boards manufactured in each Example and each Comparative Example was subjected to a tape peel test.
In addition, this tape peel test was performed according to (a) tape test method of (8) peeling test method among the test methods shown in JIS H 8504 (plating adhesion test method).

As for the wiring board manufactured by each Example, peeling from the board | substrate of an electrically conductive film was not observed, and it was confirmed that there is no problem.
On the other hand, in any of the wiring boards manufactured in each comparative example, peeling of the conductive film from the substrate was clearly visible.
In addition, it was confirmed that none of the wiring boards manufactured in each example had a problem with respect to the electrical characteristics of the conductive film.

It is a fragmentary sectional perspective view which shows an example of the wiring board of this invention. It is a figure (longitudinal section) showing a 1st embodiment of a formation method of a conductive film of the present invention. It is a figure (longitudinal sectional view) showing a second embodiment of a method for forming a conductive film of the present invention. It is a disassembled perspective view which shows embodiment at the time of applying the electronic device of this invention to a plasma display apparatus. 1 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wiring board 2 ... Board | substrate 3 ... Conductive film 31 ... Metal film 31a ... Metal particle 310 ... Metal film formation material 32 ... Plating film 321 ... 1st Film 322 ... Second film 323 ... Third film 324 ... Fourth film 4 ... Underlayer 5 ... Catalyst 500 ... Plasma display device 501, 502 ... Glass Substrate 510... Discharge display unit 511. Address electrode 512. Transparent display electrode 512 a. Bus electrode 513. Dielectric layer 514. Protective film 515. Chamber 517 ... Phosphor layer 519 ... Dielectric layer 1100 ... Personal computer 1102 ... Keyboard 1104 ... Main body 1106 ... Display unit 1200 ... Mobile phone 1202 ... Operation buttons 1204 ... Earpiece 1206 ... Mouthpiece 1300 ... Digital still camera 1302 ... Case (body) 1304 ... Light receiving unit 1306 ... Shutter button 1308 ... Circuit board 1312 ... Video signal output terminal 1314 ... Input / output terminal for data communication 1430 ... TV monitor 1440 ... Personal computer

Claims (19)

A conductive film forming method for forming a conductive film having a predetermined pattern on a substrate,
On the substrate, a metal film containing metal particles is formed by a droplet discharge method so as to be a pattern substantially equal to the pattern of the conductive film,
Then, the electroconductive plating is performed at least once to form a plating film so as to cover the surface of the metal film, thereby obtaining the conductive film.   The method for forming a conductive film according to claim 1, wherein the average thickness of the metal film is 1 to 10 μm.   The method for forming a conductive film according to claim 1 or 2, wherein the metal particles are composed mainly of at least one of gold, silver, copper, nickel, palladium, or an alloy containing these.   The method for forming a conductive film according to claim 1, wherein a catalyst is selectively applied to the surface of the metal film prior to performing the electroless plating. The electroless plating is performed a plurality of times,
5. The formation of a conductive film according to claim 1, wherein a catalyst is selectively applied to the surface of the film formed in the previous round prior to performing the electroless plating each time after the second round. Method.   The method for forming a conductive film according to claim 4 or 5, wherein the catalyst is composed mainly of at least one of palladium, platinum, rhodium, iridium, tin or an alloy containing these. The electroless plating is performed a plurality of times,
The method for forming a conductive film according to claim 1, wherein the same type of electroless plating solution is used in each electroless plating. The electroless plating is performed a plurality of times,
The method for forming a conductive film according to claim 1, wherein an electroless plating solution different from other times is used in at least one of the plurality of times of the electroless plating.   9. The method for forming a conductive film according to claim 1, wherein the plating film is composed of at least one of nickel, copper, gold, and silver as a main material.   The method for forming a conductive film according to claim 5, wherein an average thickness of the film formed by the first electroless plating is 100 to 1000 nm.   The method for forming a conductive film according to claim 1, wherein an average thickness of the plating film is 1 to 10 μm.   The method for forming a conductive film according to claim 1, wherein a base layer of the metal film is formed on the substrate prior to forming the metal film.   The method for forming a conductive film according to claim 12, wherein the base layer has a function of improving adhesion between the metal film and the substrate.   The method for forming a conductive film according to claim 12 or 13, wherein the underlayer has an insulating property.   The method for forming a conductive film according to claim 1, wherein the substrate is made of a nonmetal. A substrate,
A wiring board comprising: a conductive film formed by the method for forming a conductive film according to claim 1 on the substrate. A substrate,
A wiring board having a conductive film provided on the substrate in a predetermined pattern and including a metal film containing metal particles and a plating film provided to cover the surface of the metal film .   An electronic device comprising the wiring board according to claim 16.   An electronic apparatus comprising the electronic device according to claim 18.

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