JP2003086910A - Conductive photosensitive film and conductor pattern forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductor pattern forming method which utilizes a conductive photosensitive film capable of forming a conductor pattern on a wiring board at a low cost through a small number of processes. SOLUTION: This conductor pattern forming method comprises a laminating process of laminating a conductive photosensitive film 1 equipped with a photosensitive conductive layer 5 which contains a photopolymer component photosensitive to light hν and a conductor component on a wiring board PL and a light exposure process of exposing the photosensitive conductive layer 5 to light, corresponding to a conductor pattern, and a development process of removing an unexposed part NR from the exposed photosensitive conductive layer 5 by dissolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive photosensitive film and a method for forming a conductive pattern using the conductive photosensitive film, and in particular, for bonding electronic parts on a wiring board to construct a conductive circuit. And a conductive pattern forming method using the conductive photosensitive film.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as an IC chip, a capacitor, and a resistor are mechanically and electrically joined to each other on a wiring board by soldering to form a conductive circuit used for home appliances, information equipment terminals, and the like. The wiring board for is manufactured. These are conductors in which lead portions (leg portions) of electronic components such as IC chips and capacitors are inserted into a plurality of through holes (through holes) formed in a substantially lattice pattern on a wiring board and contact the through holes. A conductive circuit is formed by joining the pattern. Furthermore, due to advances in packaging technology, SMT (Surface Mount Tech)
A conductive circuit may be formed by directly mounting an electronic component on a wiring board without using a through hole, which is called a "surface: surface mounting technology".

At this time, as a method for forming a conductor pattern on a wiring board, a metal foil such as copper is laminated on the surface of a printed wiring board or the like, and a water-soluble dry film resist is further adhered to the surface, The resist at the portion where the circuit is formed is exposed, cured, and baked. And
A method is known in which an uncured resist is washed off from the surface of a wiring board with a developing solution, and a metal foil in a portion where the resist is removed is etched.

[0004]

However, in order to form a conductor pattern on a wiring board, it is necessary to go through a plurality of steps such as laminating, exposure, development, and etching as described above. Therefore, there are various problems such as an increase in manufacturing time and cost associated with the formation of the conductor pattern associated with multiple steps, and maintenance of manufacturing equipment for performing these steps. Furthermore, in the current wiring boards, conductor patterns may be formed in multiple layers as the packaging density increases. In this case, the above-mentioned problem becomes more serious.

In view of the above situation, the present invention is directed to a conductive photosensitive film capable of forming a conductive pattern on a wiring board in a small number of steps and at a low cost, and to form a conductive pattern using the conductive photosensitive film. The challenge is to provide a method.

[0006]

In order to solve the above-mentioned problems, the conductive photosensitive film according to the invention of claim 1 is a photopolymer component which changes its physical properties by being exposed to light of a specific wavelength, and an IC. It has a photosensitive conductive layer formed by dispersing and mixing an electronic component such as a chip and an electrically conductive component having conductivity to form a film having a uniform film thickness.

Here, the photopolymer component is composed of a material system in which a photosensitive resin composition sensitive to light of a specific wavelength (for example, ultraviolet rays) is mixed.
For example, as the material system, acrylic monomer / polymer mixed system, polythiol / polyene mixed system, oligomer / polymer mixed system, unsaturated polyester / acrylic monomer mixed system, polyamide / acrylic monomer mixed system, thermoplastic elastomer / acrylic monomer mixed system, Examples include thermoplastic elastomer / acrylic monomer / maleimide mixed system, and thermoplastic elastomer / polybutadiene / maleic acid derivative mixed system.

Further, the conductor component includes a single metal having conductivity such as copper, gold, silver, palladium, platinum, nickel, aluminum, molybdenum, and tungsten, or an alloy thereof. Then, these metals and the like are dispersed in the form of particles or powder.

Further, there are various kinds of wiring boards according to the products to be used and the uses thereof.
There are types such as those formed by impregnating epoxy resin and polyester resin, those formed of composite material using epoxy resin or polyester resin, glass base material, ceramic base material, and silicon wafer.

Further, in order to improve film forming characteristics when the photosensitive conductive layer is formed into a film, a copolymer such as methacrylic acid ester, acrylic acid ester, and styrene is used as a binder polymer for the photopolymer component and the conductive material. It may be added when the body components are dispersed and mixed. Further, the photosensitive conductive layer may contain a photopolymerization initiator, a stabilizer, a colorant and the like.

Here, in order to form the photosensitive conductive layer into a uniform film thickness, for example, on a polyethylene terephthalate (PET) film used as a base film (base material),
Applying coating technology such as wire bar, dip, roll, and blade, which are conventionally known methods,
A film shape is formed by applying the above-mentioned dispersed and mixed photopolymer components and the like while maintaining a constant film thickness, and drying or allowing to stand. This facilitates storability when not in use, regularity of the film, and handleability. Further, a protective film such as a polyethylene film is placed on the formed photosensitive conductive layer, and a three-layer structure in which the photosensitive conductive layer is sandwiched by the base film and the protective film is formed to further protect the film.

Further, the adhesion surface between the photosensitive conductive layer and each film may be coated with a silicone composition having releasability so as to provide easy peeling during use. Here, what is used for the base film and the protective film is not particularly limited, but surface smoothness, flexibility,
From the viewpoint of cost and the like, it can be said that the above-mentioned PET film and polyolefin film such as polyethylene are suitable.

Therefore, according to the conductive photosensitive film of the invention of claim 1, the photopolymer component and the conductor component are dispersed and mixed to form a photosensitive conductive layer formed into a film having a uniform film thickness. The film has. As a result, a film having both the photosensitivity to light and the conductivity due to the conductor component is formed.

According to a second aspect of the present invention, there is provided a conductive pattern forming method using the conductive photosensitive film according to the first aspect, wherein the conductive pattern forming method uses the conductive photosensitive film. A laminating step of laminating on a wiring board, an exposing step of irradiating the photosensitive conductive layer laminated by the laminating step with the light of a specific wavelength, and exposing the photosensitive conductive layer corresponding to a desired conductor pattern, and an exposing step of the exposing step. And a developing step of removing an unexposed region from the photosensitive conductive layer of the conductive photosensitive film.

Here, the conductor pattern is a wiring pattern for connecting the electronic parts to each other when the electronic parts are joined to the wiring board to form a conductive circuit. In this conductor pattern, the joint portion and the wiring portion of the electronic component are formed of a conductive metal (for example, copper) or the like.

The photopolymer component described above changes its physical properties when it is exposed to light of a specific wavelength and undergoes a photochemical reaction. For example, those having physical properties such that the solubility in a specific solvent changes can be mentioned.
Although these solvents differ depending on the type of the photopolymer component, those which are insolubilized in an organic solvent such as 1,1,1-trichloroethane, monoethanolamine, diethanolamine, sodium carbonate, potassium hydroxide,
Examples thereof include those that are insoluble in a base or weakly basic aqueous solution such as sodium hydroxide, ammonia, and quaternary ammonium salt, and those that are insoluble in water (warm water) and the like. Further, there are some that cause a photolytic reaction when exposed to light.

Therefore, when exposing to light of a specific wavelength,
For example, a mask film is formed by distinguishing a region that transmits light (exposed region) and a region that does not transmit light (unexposed region), and the mask film is superposed on a photosensitive conductive layer and exposed to light. Upon contact with the solvent, the unexposed areas are dissolved by the solvent and removed from the photosensitive conductive layer. On the other hand, the exposed area remains in the photosensitive conductive layer without being dissolved in the solvent. That is, the photosensitive conductive layer is developed with a solvent to form irregularities on the photosensitive conductive layer.

Therefore, according to the conductive pattern forming method using the conductive photosensitive film of the invention of claim 2, after laminating the conductive photosensitive film on the wiring board, it is made to correspond to a desired conductive pattern by light of a specific wavelength. To expose the photosensitive conductive layer. As a result, exposed areas and unexposed areas where the physical properties of the photopolymer component have changed are formed in the photosensitive conductive layer. Therefore, when a developing process is performed to remove the unexposed region based on the change in the physical properties of the photopolymer component (for example, due to the change in solubility), the conductor pattern in which the conductor component remains selectively on the wiring board. (Corresponds to the exposure area)
Is formed. Furthermore, the conductive component holds a predetermined height on the wiring board because the conductive photosensitive film is formed into a uniform film thickness.

According to a third aspect of the present invention, there is provided a conductive pattern forming method using a conductive photosensitive film according to the second aspect of the present invention. It has a physical property of being insoluble in an aqueous solution when exposed to, and in the developing step, the unexposed region of the photosensitive conductive layer is dissolved and removed using the aqueous solution.

Therefore, according to the conductor pattern forming method using the conductive photosensitive film of the third aspect of the invention, in addition to the function of the conductor pattern forming method using the conductive photosensitive film of the second aspect, the photopolymer is used. The component has a property of becoming insoluble in an aqueous solution when exposed to light.
Therefore, by treating the photosensitive conductive layer of the conductive photosensitive film with an aqueous solution, it becomes possible to dissolve and remove the unexposed region with the aqueous solution. That is, the development process can be performed with an aqueous solution containing water. Here, the aqueous solution depends on the type of the photopolymer component,
Examples thereof include those exhibiting basicity such as sodium carbonate aqueous solution and those exhibiting neutrality, and these are appropriately selected and used.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A conductive photosensitive film 1 according to an embodiment of the present invention and a conductive pattern forming method 2 using the conductive photosensitive film will be described below with reference to FIGS. 1 to 4. FIG. 1 is an explanatory diagram showing a configuration of a conductive photosensitive film 1 according to an embodiment of the present invention, and FIGS. 2 and 3 are explanatory diagrams illustrating a conductive pattern forming method using the conductive photosensitive film, FIG. 4 is a flowchart showing the flow of steps of a method for forming a conductor pattern using a conductive photosensitive film.

As shown in FIG. 1, the conductive photosensitive film 1 of the present embodiment is capable of conducting electricity to a photopolymer component 3 which is exposed to light hν having a specific wavelength and whose physical properties change, and electronic parts. Photosensitive conductive layer 5 formed by dispersing and mixing conductive component 4 having conductivity to form a film having a uniform thickness.
And a base film 6 that contacts one surface of the photosensitive conductive layer 5 and supports the photosensitive conductive layer 5 to maintain the film shape.
And a protective film 7 that contacts the other surface of the photosensitive conductive layer 5 to protect the surface of the photosensitive conductive layer 5, and has a three-layer structure in which the photosensitive conductive layer 5 is sandwiched between the base film 6 and the protective film 7. It is configured. Here, as the base film 6, a transparent polyester film that transmits light hν having a specific wavelength is used, while the protective film 7 is used.
Polyethylene film is used for. further,
The photosensitive conductive layer 5 of the conductive photosensitive film 1 is mixed with an acrylic acid ester-based binder polymer for shaping into a film shape. As the conductor component 4,
In this embodiment, a material composed mainly of copper is used.

Next, the conductive photosensitive film 1 of this embodiment
A conductor pattern forming method 2 utilizing the above method will be described based on explanatory views schematically shown in FIGS. 2 and 3 and a flowchart of FIG. First, as shown in FIG. 2A, the wiring board PL, the conductive photosensitive film 1, and the mask pattern 8 are prepared. Then, the photosensitive conductive layer 5 from which the protective film 7 is peeled off is laminated on the pattern forming surface 9 of the wiring board PL (laminating step S1). At this time, the base film 6 is still in contact with the photosensitive conductive layer 5. Since the photosensitive conductive layer 5 is mainly made of a polymer material, it has a slight adhesive property. Therefore, when laminating with the wiring board PL in the laminating step S1, there is no particular need for an adhesive or the like.

After that, the mask film 8 is overlaid on the base film 6 (polymerization step S2: FIG. 2B). Here, the mask film 8 has a transparent portion TP formed so that a portion of the wiring board PL that supplies the conductor component 4 transmits light hν having a specific wavelength, and the conductor component 4 on the wiring board PL.
A pattern corresponding to the desired conductor pattern CP is formed by the non-transmissive portion NP formed so that the portion not supplied with the light does not transmit the light hν.

Then, light hν is radiated from the side of the mask film 8 which is superposed (corresponding to the upper side in FIG. 2) using the exposure device 10 (exposure step S3: FIG. 2 (c)).
At this time, the exposure time and the exposure intensity for irradiating the light hν are
It is determined by the photopolymer component 3 contained in the photosensitive conductive layer 5. Further, the wavelength of the light hν to be used is selected so as to correspond to the photopolymer component 3. In addition,
In this embodiment, the light hν is used in the ultraviolet wavelength region, and the photopolymer component 3 is also used in which the photochemical reaction is caused in the ultraviolet wavelength region. The photosensitive conductive layer 5 has an exposed region ER exposed by the light hν transmitted through the transparent portion TP of the mask film 8 by exposure.
And an unexposed area NR in which the transmission of the light hν is blocked (masked) by the non-transmissive portion NP of the mask film 8 appears.

After the photosensitive conductive layer 5 has been exposed to light in the exposure step S3, the mask film 8 and the base film 6 which are in contact with the photosensitive conductive layer 5 are peeled off (peeling step S4). Then, the photosensitive conductive layer 5 on the wiring board PL is developed (developing step S5: FIG. 3A).

Specifically, the unexposed region NR in which the transmission of the light hν is masked by the mask film 8 by jetting or immersing the water-based developer L on the surface of the photosensitive conductive layer 5 Are dissolved and removed. As a result, it is possible to form the conductor pattern CP formed on the wiring board PL at a position corresponding to the exposure region ER (FIG. 3).
(B)).

As a result, compared with the conventional method of forming the conductor pattern CP, steps such as etching processing can be omitted. Therefore, it is not necessary to provide the equipment necessary for the process, and the working time for forming the conductor pattern CP can be reduced. This allows
It will be possible to increase the production capacity and reduce the manufacturing cost.

In the present embodiment, the developing process is carried out using the aqueous developing solution L in the developing step S5. Conventionally, even when a printing plate coated with a photosensitive material is made in a screen printing process, a water-based developer L is generally used.
Is often used. Therefore, existing equipment and the like can be diverted as they are, so that new equipment cost does not increase. In addition, compared to a solvent-based developer, it is more safe against fire and the like during handling, and the influence on the environment can be suppressed as much as possible.

Although the present invention has been described above with reference to the preferred embodiments, the present invention is not limited to these embodiments, and as shown below, within the scope not departing from the gist of the present invention. Various improvements and design changes are possible.

That is, the exposure step S shown in this embodiment.
3, the exposure device 9 and the mask film 8 are used to expose the photosensitive conductive layer 5. However, in this case, the mask film 8 is superposed on the wiring board by a conventionally known means. The PL, the photosensitive conductive layer 5, and the mask film 8 as a whole may be evacuated to increase the degree of adhesion on each surface. Thereby, the conductor pattern C formed
Dimensional accuracy and quality of P can be expected to improve. Further, the conductor pattern C is exposed without using the mask film 8.
It is also possible to adopt an exposure method such as performing exposure using a projection device that visualizes and projects an image corresponding to P with light hν.

Although the conductor component 4 is mainly composed of copper, the conductor component 4 is not limited to this.
Other conductive metals and alloys can be used. For example, a metal or the like conventionally used when forming a conductive circuit such as copper, gold, silver, palladium, platinum, nickel, aluminum, molybdenum, or tungsten may be appropriately selected.

Further, in the developing step S5, the one using the aqueous developer L is shown, but the invention is not limited to this, and the photopolymer component 3 contained in the photosensitive conductive layer 5 is used.
It is also possible to perform processing with a solvent-based or alkaline-based developing solution corresponding to. However, in consideration of the safety issues in carrying out the process and the influence on the global environment, the water-based one seems to be preferable.

The materials of the base film 6 and the protective film 7 used for supporting or protecting the photosensitive conductive layer 5 are not limited to those of polyester and polyethylene. In addition, the light hν having a specific wavelength for exposing the photosensitive conductive layer 5 is not limited to the ultraviolet light shown in this embodiment, and wavelengths in other regions can be used.

[0035]

As described above, the conductive photosensitive film of the invention of claim 1 has the photosensitive conductive layer containing the photopolymer component and the conductor component. As a result, a film having both a photosensitive function and a conductive function is formed with a constant film thickness.

In the conductor pattern forming method using the conductive photosensitive film according to the second aspect of the present invention, the conductive pattern can be formed on the wiring board by using the conductive photosensitive film. Therefore, as compared with the related art, the process for forming the conductor pattern can be omitted, and the manufacturing cost and the burden on the facility can be reduced. Furthermore, since the photosensitive conductive layer is formed to have a constant film thickness, the surface smoothness of the formed conductor pattern is also good, and no problems will be caused in the subsequent production of the conductive circuit.

In the conductor pattern forming method using the conductive photosensitive film of the third aspect of the invention, in addition to the effect of the conductor pattern forming method using the conductive photosensitive film of the second aspect, the developing treatment is performed by an aqueous solution. To be done,
No special equipment is required and the impact on the environment is reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing the constitution of a conductive photosensitive film.

FIG. 2 is an explanatory diagram showing an example of a conductor pattern forming method.

FIG. 3 is an explanatory diagram showing an example of a conductor pattern forming method.

FIG. 4 is a flowchart showing a flow of steps of a conductor pattern forming method.

[Explanation of symbols]

1 Conductive photosensitive film 2 Conductor pattern forming method 3 Photopolymer components 4 Conductor component 5 Photosensitive conductive layer hν light CP conductor pattern ER exposure area L water-based developer (aqueous solution) NR Unexposed area PL wiring board S1 laminating process S3 exposure process S5 development process

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01B 13/00 503 H01B 13/00 503D 5G301 H01L 21/60 311 H01L 21/60 311S 5G323 H05K 3/02 H05K 3/02 BF term (reference) 2H025 AA19 AB11 AB15 AB16 AC01 AD01 BC13 BC42 CC09 DA05 FA17 2H097 CA12 GA45 LA09 4E351 AA20 CC19 DD02 EE21 GG20 5E339 BB02 BC01 BD06 BD11 BE11 5F044 KK01 5G301 DA02 DA42 DA10 DA11 DA04 DA10 DA05 DA04 DA11 5G323 CA01

Claims (3)

[Claims] 1. A photopolymer component which is sensitive to light of a specific wavelength and whose physical properties change, and an electronic component such as an IC chip and a conductive component which has a conductive property and are dispersed and mixed to obtain a uniform film thickness. A conductive photosensitive film having a photosensitive conductive layer formed into a film. 2. A method for forming a conductor pattern using the conductive photosensitive film according to claim 1, comprising a laminating step of laminating the photosensitive conductive layer on a wiring board, and the photosensitive layer laminated by the laminating step. An exposure step of irradiating the conductive layer with the light of a specific wavelength to expose the conductive layer in accordance with a desired conductor pattern, and removing an unexposed region from the photosensitive conductive layer of the conductive photosensitive film exposed by the exposure step. A method of forming a conductor pattern using a conductive photosensitive film, comprising: a developing step. 3. The photopolymer component has a physical property of being insoluble in an aqueous solution when exposed to the light, and in the developing step, the unexposed region of the photosensitive conductive layer is formed by using the aqueous solution. The method for forming a conductor pattern using the conductive photosensitive film according to claim 2, wherein the conductor pattern is dissolved and removed.