JPH11112129A - Circuit-pattern forming method, circuit-pattern forming sheet and intermediate laminated body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conducting layer having the specified circuit pattern on an insulating base material directly and efficiently. SOLUTION: An insulating base material 2, a stripping layer 3 which has the negative pattern of the circuit pattern to be formed and is provided on the insulating base material 2, a conducting layer 4 which is provided on the insulating base material 2 through the stripping layer 3, a circuit-pattern forming sheet 1 comprising these parts described above, a negative-pattern removing sheet 9 comprising a removing-sheet base material 7 and a bonding layer 8 which is provided on the entire surface of the removing-sheet base material 7, are provided. Here, the side of the negative-pattern removing sheet 9 for the bonding layer 8 is made to face the side of the circuit-pattern forming sheet 1 for the conducting layer 4, and both sheets are attached to each other once. Thereafter, the negative-pattern removing sheet 9 is released. Thus, the conducting layer 4 at the part, where the stripping layer 3 of the circuit-pattern forming sheet 1 is formed, is moved to the negative-pattern removing sheet 9 and transferred and removed from the circuit-pattern forming sheet 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit pattern forming method and a circuit pattern forming sheet.

[0002]

2. Description of the Related Art As a method for forming a conductive layer having a predetermined circuit pattern on an insulating substrate made of glass, plastic, or the like, a circuit pattern forming method by photolithography, a circuit pattern forming method by screen printing, and a circuit by thermal transfer. A pattern forming method and the like are known.

In a circuit pattern forming method by photolithography, a conductive layer is provided on an insulating base material, a photosensitive resist film is adhered on the conductive layer and exposed in a circuit pattern form. The unexposed portion is dissolved and removed with an alkaline solution, and then the conductive layer exposed by dissolution and removal is removed with an etching solution. Then, the exposed and cured portion of the photosensitive resist film is removed with a second etching solution to remove a predetermined circuit pattern. This is a method of forming a conductive layer. However, this method has a problem that the number of steps is large and the waste liquid is harmful, so that the production cost and the waste liquid treatment cost are increased.

A circuit pattern forming method by screen printing is a method in which a metal paste or the like is applied on an insulating base material with a squeegee through a mask and then fired to form a conductive layer having a predetermined circuit pattern. However, this method has problems such as the fact that the mask is expensive, that it is complicated to accurately position the mask, and that the holes in the mask are easily clogged.

A method of forming a circuit pattern by thermal transfer is disclosed in, for example, Japanese Patent Publication No. 5-1639 and Japanese Patent Application Laid-Open No. 1-12949.
As disclosed in Japanese Patent Laid-Open No. 2 (1993) -207, a conductive material is contained in an ink layer provided on a thermal transfer sheet, the ink layer is transferred onto an insulating substrate by a heating device such as a thermal head, and a predetermined circuit is formed. This is a method of transferring and forming as a conductive layer of a pattern. However, the ink layer requires a binder in order to apply the conductive material contained therein to the substrate of the thermal transfer sheet and to transfer the conductive material onto the insulating substrate. However, binder components such as wax and synthetic resin have high resistance values. For this reason, the resistance value of the transferred conductive layer becomes high, and it is difficult to obtain a predetermined resistance value.
Also, to adjust the resistance value, thicken the ink layer,
Although the content of the conductive material in the ink layer is increased, it is difficult to optimize the resolution of the circuit pattern and the printing sensitivity. Further, in consideration of mass productivity, there is an inconvenience that the size of a pattern that can be thermally transferred onto an insulating substrate continuously is limited by the width of a heating device such as a thermal head.

On the other hand, JP-A-60-160693 and JP-A-3-87089 disclose that a conductive layer provided on a circuit pattern forming sheet is provided with a predetermined circuit on an insulating substrate via an adhesive layer. A method of transferring and forming a pattern (hereinafter, referred to as “pattern transfer method”) is disclosed.

According to the pattern transfer method disclosed in Japanese Patent Application Laid-Open No. 60-160693, a circuit pattern forming sheet is formed by providing a release layer, a conductive layer, and an adhesive layer in this order on a supporting substrate. You. Of these, a release layer or an adhesive layer is provided in a predetermined circuit pattern. An insulating substrate is stuck on the adhesive layer of such a circuit pattern forming sheet,
Thereafter, when the conductive layer is peeled off, the conductive layer is peeled off at the interface with the release layer, and a predetermined circuit pattern is transferred and formed on the insulating base material via the adhesive layer.

According to the pattern transfer method disclosed in JP-A-3-87089, a circuit pattern forming sheet is
A release layer and a conductive layer are provided on a support base in this order. On the conductive layer of the circuit pattern forming sheet thus formed, the adhesive layer side of the insulating base material provided with the adhesive layer having the predetermined circuit pattern is bonded and then peeled off, so that the conductive layer and the release layer are separated. At the interface, and a predetermined circuit pattern is transferred and formed on the insulating substrate via the adhesive layer.

In any of these pattern transfer methods, an adhesive layer or a peeling layer is provided in a predetermined circuit pattern, and the adhesive force between the conductive layer and the adhesive layer, the adhesive force between the conductive layer and the peeling layer, or the conductive layer and the supporting substrate is used. The conductive layer is transferred to a predetermined circuit pattern by the strength of the adhesive force between them.

[0010]

Such a pattern transfer method is superior in mass productivity as compared with a thermal transfer method using a thermal head or the like.

However, the circuit board on which a predetermined circuit pattern is transferred and formed by the above-described method has an adhesive layer between the insulating base material and the conductive layer. Sex may change.
Further, when the adhesive layer is provided on the entire surface, the insulating property of the adhesive layer may change with time. Further, when brazing to the conductive layer by soldering or the like, the bonding layer may be degraded by the brazing temperature and affect the adhesiveness and the like.

An object of the present invention is to provide an efficient circuit pattern forming method capable of providing a conductive layer having a predetermined circuit pattern directly and efficiently on an insulating substrate, and a circuit pattern for forming such a circuit pattern. An object is to provide a formed sheet and an intermediate laminate.

[0013]

According to the present invention, in order to achieve the above object, there is provided an insulating substrate and a peeling-off device having a negative pattern of a circuit pattern to be formed and provided on the insulating substrate. A circuit pattern forming sheet comprising a layer and a conductive layer provided on the entire surface of the insulating base material via the release layer, and a base material for the removal sheet, and provided on the entire surface of the base material for the removal sheet. Prepare a negative pattern portion removal sheet consisting of an adhesive layer, the adhesive layer side of the negative pattern portion removal sheet facing the conductive layer side of the circuit pattern forming sheet, once both sheets are bonded, By peeling the negative pattern portion removing sheet, the conductive layer in the portion of the circuit pattern forming sheet where the release layer is formed is transferred to the negative pattern portion removing sheet, and the circuit pattern forming sheet is removed. To provide a circuit pattern forming method, and removing from and.

Further, in the present invention, an insulating base material,
A release layer having a negative pattern of a circuit pattern to be formed and provided on the insulating substrate, and a conductive layer provided on the entire surface of the insulating substrate via the release layer. And a circuit pattern forming sheet. This circuit pattern forming sheet is a novel laminate used in the above-described circuit pattern forming method.

Further, in the present invention, the circuit pattern forming sheet and the negative pattern part removing sheet are arranged such that the adhesive layer side of the negative pattern part removing sheet faces the conductive layer side of the circuit pattern forming sheet. The present invention provides an intermediate laminated body characterized in that the intermediate laminated body is laminated. This intermediate laminate is a useful laminate formed during the implementation of the circuit pattern forming method described above.

An insulating substrate, a release layer having a negative pattern of a circuit pattern to be formed, provided on the insulating substrate, and provided on the entire surface of the insulating substrate via the release layer. A circuit pattern forming sheet comprising a conductive layer, and a negative pattern portion removing sheet comprising a substrate for a removal sheet and an adhesive layer provided on the entire surface of the substrate for a removal sheet; After laminating so that the layer side and the adhesive layer of the negative pattern portion removing sheet are opposed to each other, the two sheets are peeled off, and the conductive layer in the portion where the peeling layer of the circuit pattern forming sheet is formed removes the negative pattern portion. After the transfer to the sheet, the conductive layer remains on the insulating substrate in a circuit pattern. There is no adhesive layer between the conductive layer remaining in the circuit pattern and the insulating substrate.

When the negative pattern portion removing sheet is peeled off from the circuit pattern forming sheet, peeling occurs between the insulating substrate and the peeling layer, and the peeling layer is formed on the insulating pattern together with the conductive layer in the negative pattern portion. It may be removed from above, or the peeling may occur between the peeling layer and the conductive layer and only the conductive layer of the negative pattern portion may be removed from the insulating base material. Is preferably removed together.

According to the method of the present invention, unlike the case of the thermal transfer method using a thermal head, a circuit pattern can be formed on an insulating base material without blending a binder component in the conductive layer. As in the case described above, it is possible to form a circuit pattern having a low resistance value substantially made of only a conductive material.

In particular, when a metal film, for example, a metal evaporation film such as an aluminum evaporation film is formed as a conductive layer of the circuit pattern formation sheet by a vapor phase plating method, not only can the resistance value be lowered, but also the circuit pattern can be reduced. The adhesion between the conductive layer of the portion and the insulating base material is high. Therefore, the durability of the circuit pattern is improved, and the conductive layer of the circuit pattern portion is less likely to be formed on the sheet for removing the negative pattern portion when the circuit pattern is formed.

In the present invention, the insulating substrate, a release layer having at least two sets of negative patterns of a circuit pattern to be formed, provided on the insulating substrate, A circuit pattern forming sheet including a conductive layer provided on the entire surface of the conductive substrate may be used. A circuit pattern forming sheet having two or more sets of circuit pattern negative patterns and a negative pattern portion removing sheet, wherein the negative pattern is formed such that the conductive layer side of the circuit pattern forming sheet and the adhesive layer of the negative pattern portion removing sheet face each other. When the negative-pattern-removing sheet is peeled off after laminating the part-removing sheets and once applying the two sheets by roll pressing or roll heating / pressing, two or more sets of circuit patterns can be continuously formed. Good productivity.

[0021]

FIG. 1 is a sectional view showing an example of a circuit pattern forming sheet of the present invention. The circuit pattern forming sheet 1 includes an insulating substrate 2, a release layer 3 provided on the insulating substrate 2 as a negative pattern of a circuit pattern to be formed, and the release layer 3 and the release layer 3. And a conductive layer 4 provided on the entire surface so as to cover any of the insulating base materials 2. For this reason, the circuit pattern forming sheet 1 includes a negative pattern portion 5 formed on the insulating base material 2 in the order of the release layer 3 and the conductive layer 4, and a conductive layer directly provided on the insulating base material 2. And the circuit pattern section 6 composed of

FIG. 2 is a schematic sectional view showing an example of the circuit pattern forming method of the present invention using the circuit pattern forming sheet 1.

As a circuit pattern forming method, first, on the conductive layer 4 side of the circuit pattern forming sheet 1, a negative pattern portion removing sheet 9 composed of a substrate 7 for removing sheet and an adhesive layer 8 is provided.
The two sheets are once bonded together with the side of the adhesive layer 8 facing the other. FIG. 3 shows the structure of the intermediate laminate 16 formed by laminating both sheets.

Next, by peeling the negative pattern portion removing sheet 9 from the intermediate laminate 16, the conductive layer 4 in the portion of the circuit pattern forming sheet 1 where the release layer 3 is formed (negative pattern portion 5) becomes negative. The process proceeds to the pattern portion removing sheet 9 and is removed from the circuit pattern forming sheet 1. In this way, a circuit pattern 14 as shown in the cross-sectional view of FIG. 4 is formed by the conductive layer 4 remaining on the insulating substrate 2 without being removed. The transfer of the conductive layer 4 of the negative pattern portion 5 provided on the circuit pattern forming sheet 1 to the negative pattern portion removing sheet 9 and removing the conductive layer 4 from the circuit pattern forming sheet 1 is hereinafter referred to as “transfer”. That.

According to the present invention, unlike the conventional pattern transfer method, there is no need to interpose an adhesive layer between the insulating base material 2 and the conductive layer 4 left in a circuit pattern.

As shown in FIG. 2, after laminating the circuit pattern forming sheet 1 and the negative pattern portion removing sheet 9,
The sheet 9 for removing the negative pattern is peeled off, and the insulating substrate 2 is removed.
In order to leave the conductive layer 4 on the upper surface in a pattern, at least the following relationship is established during the transfer to the adhesion between the stacked layers.

A>B> C1 or A>B> C2, where: Adhesive force between the insulating base material 2 and the conductive layer 4: A; Adhesive force between the conductive layer 4 and the adhesive layer 8: B; The adhesion between the substrate 2 and the release layer 3 is C1, and the adhesion between the release layer 3 and the conductive layer 4 is C2.

Preferably, A>B> C1, where C2> C1.

Since the respective layers are in close contact with each other in such a relationship, the conductive layer 4 of the circuit pattern portion 6 directly provided on the insulating base material 2 is most closely adhered (adhesion force: A). Therefore, the circuit pattern 14 is always left on the insulating base material 2 to form the circuit pattern 14.

The conductive layer 4 of the negative pattern portion 5 provided on the release layer 3 has an adhesive property (adhesion: C) to the release layer 3.
Since the adhesiveness (adhesion force: B) to the adhesive layer 8 is stronger than 2), it is removed by the adhesive layer 8 of the negative pattern portion removing sheet 9 without remaining on the insulating base material 2 after transfer. You. At this time, the adhesion between the release layer 3 and the conductive layer 4 (adhesion: C2)
Is the adhesion between the insulating substrate 2 and the release layer 3 (adhesion: C
If it is weaker than 1), the conductive layer 4 peels off at the interface with the release layer 3, so that the release layer 3 remains on the insulating base material 2. On the other hand, if the adhesion between the release layer 3 and the conductive layer 4 (adhesion: C2) is stronger than the adhesion between the insulating base material 2 and the release layer 3 (adhesion: C1), the release layer 3 has an insulating property. It is peeled off at the interface with the substrate 2 and is removed together with the conductive layer by the adhesive layer 8 of the negative pattern portion removing sheet 9. As described above, the multilayer structure of the negative pattern portion 5 may be separated at the interface between the conductive layer 4 and the release layer 3 or may be separated between the release layer 3 and the insulating substrate 2. Preferably the latter.

The shear strength (D) at the boundary 15 between the conductive layer 4 of the negative pattern portion 5 and the conductive layer 4 of the circuit pattern portion 6 is determined by the adhesion (B) between the conductive layer 4 and the adhesive layer 8. Also, the conductive layer 4 of the negative pattern portion 5 and the conductive layer 4 of the circuit pattern portion 6 are cut and cut at the boundary 15. As a result, the conductive layer 4 of the negative pattern part 5 is removed by the adhesive layer 8, and the conductive layer 4 of the circuit pattern part 6 remains on the insulating base material 2 and becomes a circuit pattern 14.

In any case, according to the present invention, the negative pattern portion 5 is left while the conductive layer of the circuit pattern portion 6 is left.
It is necessary to transfer the conductive layer to the negative pattern portion removal sheet. Therefore, the adhesion between the insulating substrate 2 and the release layer 3, the adhesion between the insulating substrate 2 and the conductive layer 4, the adhesion between the conductive layer 4 and the adhesive layer 8, and the separation from the conductive layer 4 The adhesion between the layers 3 is adjusted so as to maintain an appropriate balance during transfer. Such adjustment can be performed by, for example, mixing a material whose adhesiveness or releasability changes by heating or pressurization, such as a thermoplastic resin or a wax, into the release layer 3 or the adhesive layer 8, It can be done by selecting the material.

To bond the circuit pattern forming sheet 1 and the negative pattern portion removing sheet 9, an adhesive layer between the conductive layer 4 side of the circuit pattern forming sheet 1 and the negative pattern portion removing sheet 9 is formed on the circuit pattern forming sheet 1. The negative pattern portion removing sheet 9 may be overlapped so that the sheet 8 faces the negative pattern portion 8 and pressed by an arbitrary method such as flat plate pressing or roll pressing. At this time, by pressing while heating to an appropriate temperature according to the thermal properties of the peeling layer 3 of the circuit pattern forming sheet 1 and the adhesive layer 8 of the negative pattern portion removing sheet 9, the multilayer structure of the negative pattern portion 5 is formed. Of the circuit pattern forming sheet 1 from the negative pattern portion removing sheet 9
Transferability can be improved.

The circuit pattern forming sheet 1 and the negative pattern portion removing sheet 9 may be in the form of a continuous sheet.
As shown in FIG. 2, a continuous sheet-like circuit pattern forming sheet 1 having two or more sets of negative patterns of a circuit pattern to be formed and a continuous sheet-like negative pattern portion removing sheet 9 are also used for an insulating base material. The roll sheet 17 is rolled out from the circuit pattern forming sheet roll stock 18 and overlapped, and the two sheets are bonded and peeled by applying pressure using a rotating pressure roller 10 to thereby form a sheet.
More than a set of circuit patterns can be continuously and efficiently formed. The pressure roller 10 may be a heating / pressure roller so that the heating operation can be performed simultaneously. The continuous sheet-like insulating base material with the circuit pattern and the used negative pattern portion removal sheet obtained by this method are wound around the respective winding rolls 11 and 12 in a roll shape and collected. Preferred from the point.

The layers constituting the circuit pattern forming sheet 1 and the negative pattern portion removing sheet 9 and the method of forming the layers will be described below.

First, the layers constituting the circuit pattern forming sheet 1 and the method of forming the layers will be described.

[Insulating Base Material] Since the insulating base material 2 has the circuit pattern 14 formed of the conductive layer 4 thereon, any material having excellent electrical insulation properties can be used. Good. The insulating base material 2 is provided directly on the insulating substrate 2 so that the adhesive force (A) with the conductive layer 4 constituting the circuit pattern portion 6 is the strongest among the adhesive forces between the other layers. Is appropriately selected according to the use of the circuit board and the type of the conductive layer 4.

As the generally used insulating substrate 2, for example, a plate or a film of glass, ceramic, paper, plastic, glass epoxy or the like can be used.
Among them, it is preferable to use polyethylene terephthalate, polyethylene naphthalate, or the like from the viewpoint of insulation. Further, when they are in the form of a film, they are excellent in mass productivity and can achieve a thin circuit board. Is more preferable. In this case, since the obtained circuit board has flexibility, the circuit board can be wound around the circuit board winding roll 12, so that it is efficient.

The thickness of the insulating substrate 2 is not particularly limited, but is usually about 12 to 250 μm.

[Release Layer] By providing the release layer 3,
The required releasability for smoothly transferring the conductive layer 4 existing in the negative pattern portion 5 of the circuit pattern forming sheet 1 to the negative pattern portion removing sheet 9 can be secured.

The peeling layer 3 has an adhesive force (C
1) Or provided on the insulating substrate 2 as a negative pattern of a circuit pattern to be formed, so that the adhesion (C2) to the conductive layer 4 has the above-described relationship. For this reason, the release layer 3 is easily peeled off from the insulating substrate 2 together with the conductive layer forming the negative pattern portion 5, or the conductive layer 4 on the release layer 3 is replaced with the adhesive layer 8 of the negative pattern portion removal sheet 9. Can be easily transferred.

The properties required for the release layer 3 include excellent releasability from the insulating substrate 2, appropriate adhesion to the insulating substrate 2, and maintenance of the form when the conductive layer 4 is formed. Heat resistance and the like are required. The degree of such a property varies depending on the types of the insulating base material 2 and the conductive layer 4, and thus, the release layer 3 is formed by mixing a material according to the degree or the material. For example, waxes such as carnauba wax and paraffin wax are used when peelability is considered, and polyester resin, ethylene-vinyl acetate copolymer resin (EVA), ethylene-acrylic acid copolymer are used when adhesion is considered. A thermoplastic resin such as a polymer resin (EAA), an acrylic resin, and an ionomer resin is used. When the conductive layer 4 is formed by a vapor phase plating method, for example, metal deposition, a heat-resistant resin such as a polyamide-imide resin or nitrocellulose is used to impart heat resistance to the release layer 3.

Of these, a mixture of an ionomer resin and a wax is particularly preferably used from the viewpoints of adhesion to a polyethylene terephthalate film preferably used as the insulating substrate 2 and releasability at the time of pressing the roller.

The release layer 3 is prepared by dissolving or dispersing the above-mentioned material in an appropriate solvent to prepare a release layer coating liquid, and applying the coating liquid on the insulating substrate 2 by gravure printing, screen printing, or gravure reverse. By means such as coating method
It can be formed by applying and drying with a negative pattern of a circuit pattern to be formed. The coating amount is usually 0.1 to 5 μm as a coating thickness after drying.

[Conductive Layer] The conductive layer 4 is formed on the insulating base material 2.
The release layer 3 is formed on the entire surface so as to cover both the release layer 3 formed in the negative pattern and the insulating substrate 2 on which the release layer 3 is not formed. The formed conductive layer 4 includes a negative pattern portion 5 on the release layer 3 and a circuit pattern portion 6 formed directly on the insulating base material 2. Circuit pattern 14
After bonding the adhesive layer 8 of the negative pattern portion removing sheet 9 on the conductive layer 4, the negative pattern portion removing sheet 9 was peeled off to remove the negative pattern portion 5 and remained on the insulating base material 2. It is formed accurately by the conductive layer 4 of the circuit pattern portion 6.

The conductive layer 4 is preferably a layer substantially composed of only a conductive material. According to the present invention, since a conductive layer can be formed without using a binder component having a high resistance value, a circuit pattern having high conductivity can be formed. Examples of the material used for the conductive layer 4 include metals such as copper, nickel, aluminum, tin, lead, indium, bismuth, thallium, gold, silver, zinc and alloys thereof, carbon, and paste containing metal powder. To
It can be appropriately selected and used depending on the required resistance value.

When the metal is used as the conductive layer 4, it can be formed by a vapor deposition method such as a vacuum deposition method, a sputtering method, or an ion plating method, and is particularly preferably formed by a vacuum deposition method. Since the thickness of the conductive layer 4 formed by the vacuum evaporation method can be easily controlled, a circuit pattern having a desired resistance value can be formed, and the adhesion to the insulating base material 2 is increased. be able to. When the conductive layer 4 is formed of a material other than metal, it can be formed by a conventionally known method, for example, a coating method.

The thickness of the conductive layer 4 depends on the finally required resistance value, pattern width, etc. of the circuit pattern.
001 μm (10 °) to about 50 μm, particularly 0.05 μm
m (500 °) to 0.5 μm (5000 °) is preferred.

Next, each layer constituting the negative pattern portion removal sheet 9 and its forming method will be described.

[Substrate for Removal Sheet] Substrate for Removal Sheet 7
Is used as a support for transferring and removing the negative pattern portion 5 of the circuit pattern forming sheet 1 by the adhesive layer 8 provided thereon. The substrate 7 for the removal sheet to be used can be selected from a wide range of materials including resin films, papers, metals and the like, and is usually a polyester film such as a polyethylene terephthalate film, a polyolefin film such as a polyethylene film and a polypropylene film. , A polyimide film or the like can be used. Among these, a polyethylene terephthalate film is preferably used from the viewpoint of economy and ease of handling.

The thickness of the removal sheet substrate 7 is not particularly limited, but is usually about 2 to 150 μm.

[Adhesive Layer] The adhesive layer 8 adheres to the conductive layer 4 of the circuit pattern forming sheet 1 in the relationship of the adhesive force (B) described above, and the circuit pattern forming sheet and the negative pattern portion 5 are transferred and removed. In order to do so, it is formed on the base material 7 for the removal sheet. The adhesive layer 8 formed at this time is not peeled off from the substrate for removal sheet 7 during transfer, and the conductive layer 4 of the circuit pattern portion 6 is left on the insulating substrate 2 while the negative pattern portion is left. 5 are provided so that the conductive layer 4 can be removed.

The material constituting the adhesive layer 8 is appropriately selected depending on the type of the base material 7 for the removal sheet and from the viewpoint of the adhesiveness to the metal layer preferably formed as the conductive layer 4. Resin, ethylene-vinyl acetate copolymer resin (EVA), acrylic resin, ethylene-
Acrylic acid copolymer resin (EAA), thermoplastic resin such as polyethylene resin or urethane resin, wax such as carnauba wax, polyethylene wax or paraffin wax, or a mixture thereof can be used. If necessary, a reinforcing agent, A plasticizer, a filler and the like can be added and used. Among them, EAA is particularly preferably used from the viewpoint of adhesion to a metal layer preferably formed as the conductive layer 4.

The adhesive layer 8 is prepared by dissolving or dispersing the above-mentioned materials in an appropriate solvent to prepare a coating liquid for the adhesive layer, and applying the coating liquid on the substrate 7 for the removal sheet by a gravure printing method, a screen printing method, or the like. It can be formed by applying and drying by means such as a reverse coating method. The coating amount is usually 0.1 μm to 10 as a coating thickness after drying.
μm.

[0055]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a circuit pattern forming method and a circuit pattern forming sheet 1 according to the present invention will be specifically described.

Example 1 First, a polyethylene terephthalate film having a thickness of about 100 μm was used as the insulating substrate 2. On the insulating substrate 2, a gravure direct printing method is used such that a coating solution for a release layer having the following composition has a thickness of about 0.5 μm after drying and has a negative pattern with respect to a circuit pattern to be formed. Coating, drying and release layer 3
Was formed. Further, aluminum is coated to a thickness of about 0.05 μm (500 °) so as to cover both the negative pattern of the release layer 3 and the insulating substrate 2 on which the release layer 3 is not formed.
Vacuum evaporation method (reduced pressure to 10 ^-5 Torr or less)
Thus, a conductive layer 4 was formed. Thus, the circuit pattern forming sheet 1 was produced.

Coating solution for release layer; Carnauba wax emulsion (solid content 40%, melting point 82 ° C.) 30 parts by weight NBR (acrylonitrile-butadiene copolymer rubber) emulsion (solid content 40%, Tg: 20 ° C.) 10 parts by weight 40 parts by weight of IPA 20 parts by weight of water Next, a polyethylene terephthalate film having a thickness of about 6 μm was used as the base material 7 for the removal sheet.
The coating weight after drying the adhesive layer coating liquid having the following composition is 1
g / m ² was applied by a gravure reverse coating method and dried to form an adhesive layer 8, thereby producing a negative pattern portion removal sheet 9.

Coating liquid for adhesive layer; Ethylene-acrylic acid copolymer resin (EAA) emulsion (solid content 30%) 20 parts by weight Polyester resin emulsion (solid content 20%, Tg: 20 ° C.) 20 parts by weight IPA 40 20 parts by weight of water 20 parts by weight of water The adhesive layer 8 of the sheet 9 for removing a negative pattern portion was adhered to the conductive layer 4 of the obtained circuit pattern forming sheet 1 through a heating / pressing roller 10 using a laminator.
Thereafter, the negative pattern portion removing sheet 9 is peeled off from the circuit pattern forming sheet 1 so that the insulating base material 2 is removed.
The upper negative pattern portion 5 was transferred to the negative pattern portion removal sheet 9. As a result, the conductive layer 4 of the circuit pattern portion 6 remained on the insulating base material 2, and the circuit pattern 14 was formed. Thus, the circuit board of Example 1 was obtained.

(Example 2) In the circuit pattern forming method of Example 1, a coating liquid for a release layer having the following composition was used in place of the coating liquid for a release layer, and coating was performed in the same manner as in Example 1. After drying, a release layer 3 having a thickness of about 0.5 μm was formed. The other conditions were the same as in Example 1 to obtain a circuit board of Example 2.

Coating solution for release layer; Carnauba wax emulsion (solid content 40%, melting point 82 ° C.) 10 parts by weight Ionomer resin emulsion (solid content 30%, MFT (minimum film forming temperature): 90 ° C.) 30 parts by weight IPA 40 parts by weight 20 parts by weight of water (Example 3) In the method of forming a circuit pattern of Example 2, instead of the conductive layer 4, which is an aluminum deposited film of about 0.05 μm (500 °), about 0.15 μm (1500)
An aluminum deposited film having a thickness of Å) was formed as the conductive layer 4. Otherwise, the circuit pattern forming sheet 1 was produced in the same manner as in Example 2.

Next, an adhesive layer 8 was formed in the same manner as in Example 2 except that an adhesive layer coating liquid having the following composition was used instead of the adhesive layer coating liquid. Others were the same as Example 2, and obtained the circuit board of Example 3.

Acrylic ester resin emulsion (solid content 40%, Tg: -50 ° C.) 30 parts by weight Paraffin wax emulsion (solid content 30%, melting point 67 ° C.) 20 parts by weight IPA 30 parts by weight 20 parts by weight of water (Comparative Example 1) First, a thickness of about 100 μm was used as an insulating substrate.
Of polyethylene terephthalate film was prepared.

Next, a polyethylene terephthalate film having a thickness of about 6 μm was used as a base material for a thermal transfer sheet, and the following component materials for the conductive ink layer were placed thereon.
A conductive ink layer coating liquid obtained by kneading under melting at 0 ° C.
Coating was performed by a roll coating method so that the thickness after drying was about 10 μm, and the coating was dried to prepare a thermal transfer sheet having a conductive ink layer.

Aluminum powder 50 parts by weight Paraffin wax 30 parts by weight Carnauba wax 10 parts by weight EVA resin 10 parts by weight The conductive ink layer of the thermal transfer sheet was formed by using a thermal head to the above-mentioned thickness. Thermal transfer was performed on a polyethylene terephthalate film having a thickness of about 100 μm so as to form a predetermined circuit pattern. Thus, a circuit board of Comparative Example 1 was obtained.

(Evaluation Method and Evaluation Results) Using the circuit boards obtained in the above Examples and Comparative Examples, the resistance value of each conductive circuit and the mass productivity of the circuit boards were examined. The circuit pattern formed on each circuit board has a width of 2 mm ×
A coil shape corresponding to a line having a length of 500 mm was formed. A general tester was used for measuring the resistance value. Table 1 shows the obtained evaluation results.

[0066]

[Table 1] In Examples 1 and 2, since the aluminum vapor-deposited layer is provided as the conductive layer 4, not only the resistance value is lowered, but also the adhesion between the polyethylene terephthalate film as the insulating substrate 2 and the aluminum vapor-deposited layer. Due to the excellent properties, the aluminum vapor-deposited layer of the circuit pattern portion 6 was hardly removed on the negative pattern portion removal sheet 9, and the incidence of defective products was significantly reduced. Further, since the laminating and peeling were continuously performed using the heating / pressing roller 10, the mass productivity was excellent. Further, the release layer 3 showed excellent release properties, and the negative pattern portion 5 could be easily released from the polyethylene terephthalate film as the insulating substrate 2.

In Example 3, a circuit board having a lower resistance could be obtained because the aluminum vapor-deposited layer as the conductive layer 4 was thick. Further, even when the adhesive layer 8 was replaced, the conductive layer 4 of the negative pattern portion 5 could be successfully peeled. The mass productivity was excellent as in Examples 1 and 2.

In Comparative Example 1, a circuit pattern was formed by thermal transfer on an insulating substrate from a thermal transfer sheet provided with a conductive ink layer, and a binder was compounded in the conductive ink layer. Therefore, the resistance value of the obtained circuit board was high. Furthermore, since the width of the circuit pattern is limited by the width of the thermal head, many circuit patterns cannot be formed at once, resulting in poor mass productivity.

[0069]

As described above, according to the circuit pattern forming method and the circuit pattern forming sheet of the present invention, after bonding the circuit pattern forming sheet and the negative pattern portion removing sheet, the two sheets are peeled off. As a result, the conductive layer in the portion where the release layer of the circuit pattern forming sheet is formed is transferred to the negative pattern portion removing sheet, and the conductive layer remains in the circuit pattern on the insulating base material of the circuit pattern forming sheet. A pattern is formed. Since there is no adhesive layer between the conductive layer remaining in the circuit pattern and the insulating substrate, there is no problem caused by the adhesive layer.

Also, unlike the case of the thermal transfer method using a thermal head, a circuit pattern can be formed on an insulating base material without blending a binder component in the conductive layer. Thus, a circuit pattern having only a low resistance value and made of only a conductive material can be easily formed. Further, the formation of the circuit pattern is not complicated as compared with the etching method and the screen printing method, and a waste liquid treatment and an expensive mask are not required, so that the circuit pattern can be formed at low cost.

In particular, when a metal deposition film is formed as a conductive layer, not only can the resistance value be lowered,
This is extremely preferable because the adhesion to the insulating base material is increased, the durability of the circuit pattern is improved, and the incidence of defective products is reduced.

Further, according to the present invention, a circuit pattern forming sheet having at least two or more sets of circuit pattern negative patterns and a negative pattern portion removing sheet are overlapped, and both sheets are once bonded together by roll pressing, and then the negative is applied. By peeling off the pattern portion removing sheet, two or more sets of circuit patterns can be continuously formed, so that productivity can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a circuit pattern forming sheet of the present invention.

FIG. 2 is a schematic sectional view illustrating an example of a circuit pattern forming method according to the present invention.

FIG. 3 is a cross-sectional view showing an example of an intermediate laminate of the present invention in which a circuit pattern forming sheet and a negative pattern portion removing sheet are bonded.

FIG. 4 is a sectional view showing an example of a circuit board obtained by the circuit pattern forming method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Circuit pattern forming sheet 2 Insulating base material 3 Release layer 4 Conductive layer 5 Negative pattern part 6 Circuit pattern part 7 Removal sheet base material 8 Adhesive layer 9 Negative pattern part removal sheet 10 Transfer roller 11 Used negative pattern part Take-up roll for removing sheet 12 Take-up roll for continuous sheet-like insulating base material with circuit pattern 13 Circuit board 14 Circuit pattern 15 Boundary part 16 Intermediate laminate 17 Roll stock for insulating base material 18 Roll for circuit pattern forming sheet stock

Claims (8)

[Claims] 1. An insulating substrate, a release layer having a negative pattern of a circuit pattern to be formed and provided on the insulating substrate, and an entire surface of the insulating substrate via the release layer. A circuit pattern forming sheet comprising the provided conductive layer, and a substrate for a removal sheet, and a negative pattern portion removal sheet comprising an adhesive layer provided on the entire surface of the substrate for the removal sheet are prepared. The adhesive layer side of the negative pattern portion removal sheet is opposed to the conductive layer side of the pattern formation sheet, and after the two sheets are pasted together, the negative pattern portion removal sheet is peeled off, thereby removing the circuit pattern formation sheet. A method for forming a circuit pattern, comprising: transferring a portion of the conductive layer where a release layer is formed to the negative pattern portion removal sheet and removing the conductive layer from the circuit pattern formation sheet. 2. The method according to claim 1, wherein the conductive layer is substantially made of only a conductive material. 3. The circuit pattern forming method according to claim 2, wherein the conductive layer substantially made of only a conductive material is a metal film formed by a vapor phase plating method. 4. The circuit pattern forming sheet, comprising: an insulating base material; a release layer provided on the insulating base material having two or more sets of negative patterns of a circuit pattern to be formed;
A conductive layer provided on the entire surface of the insulating base material via the release layer; and an adhesive layer on the conductive layer side of the circuit pattern forming sheet and the negative pattern portion removing sheet on the circuit pattern forming sheet. The negative pattern portion removing sheet is overlapped such that the sheets face each other, and the two sheets are once bonded together by roll pressing or roll heating / pressing, and then the negative pattern portion removing sheet is peeled off. 2. The circuit pattern forming method according to claim 1, wherein the pattern is formed continuously. 5. An insulating substrate, a release layer having a negative pattern of a circuit pattern to be formed and provided on the insulating substrate, and an entire surface of the insulating substrate via the release layer. A circuit pattern forming sheet comprising a conductive layer provided. 6. The circuit pattern forming sheet according to claim 5, wherein the conductive layer is substantially made of only a conductive material. 7. The circuit pattern forming sheet according to claim 6, wherein the conductive layer substantially composed of only a conductive material is a metal film formed by a vapor phase plating method. 8. An insulating base material, a release layer having a negative pattern of a circuit pattern to be formed, provided on the insulating base material, and provided on the entire surface of the insulating base material via the release layer. A circuit pattern forming sheet comprising the provided conductive layer, a substrate for the removal sheet, and a negative pattern portion removal sheet comprising an adhesive layer provided on the entire surface of the substrate for the removal sheet; An intermediate laminate, wherein the sheet is bonded so that the adhesive layer side of the negative pattern portion removal sheet faces the conductive layer side of the sheet.