WO2016136497A1

WO2016136497A1 - Circuit sheet and circuit sheet production method

Info

Publication number: WO2016136497A1
Application number: PCT/JP2016/054112
Authority: WO
Inventors: 真一友岡
Original assignee: ポリマテック・ジャパン株式会社
Priority date: 2015-02-27
Filing date: 2016-02-12
Publication date: 2016-09-01
Also published as: JPWO2016136497A1; DE112016000938T5; CN107251662A; JP6804713B2; CN107251662B

Abstract

The objective of the invention is to produce, more simply and at a lower cost than in the prior art, a circuit sheet comprising a circuit pattern formed on each side of a resin film and having conductivity therebetween. Formed by perforation in the resin film 11 is an opening 14 for exposing a first conductive layer 12 serving as a circuit pattern. Formed in a second conductive layer 13 serving as a circuit pattern is an invaginating portion 15 penetrating into the opening 14. The circuit sheet 10 comprises the first conductive layer 12 and the second conductive layer 13 conductively interconnected at a conductive contact portion 16.

Description

Circuit sheet and method for manufacturing circuit sheet

The present invention relates to a circuit sheet used in various electric devices. More specifically, the present invention relates to a circuit sheet having circuit patterns on both surfaces of a resin film, and the circuit patterns on both surfaces being conducted.

Circuit sheets such as membrane sheets used in various electric devices have circuit patterns on both surfaces of the resin film, and the circuit patterns on both surfaces are conducted through through holes. In this membrane sheet, a complicated circuit wiring can be designed by arranging circuit patterns on both surfaces of the resin film. Such a technique is described in, for example, Japanese Patent Application Laid-Open No. 2007-214240 (Patent Document 1).

Here, a conventional method for forming a circuit pattern using a conductive paste will be described. First, as shown in FIG. 7A, a conductive paste (first conductive layer coating) is applied to one surface s1 of a resin film 1. The first conductive layer 2 is formed by applying a liquid. Next, as shown in FIG. 7B, through holes 3 are formed in the resin film 1 and the first conductive layer 2 using punching, cutting, drilling with a needle, a method using a laser, or the like. And as shown in FIG.7 (C), the 2nd conductive layer 4 is apply | coated by apply | coating a conductive paste (coating liquid for 2nd conductive layers) from the opposite surface s2 of the resin film 1 in which the through-hole 3 opened. Form. At this time, the second conductive layer 4 that has entered the through hole 3 comes into contact with the first conductive layer 2 formed on the one surface s1 to form a conduction path 5.

However, according to this method, since the conductive paste (the second conductive layer coating liquid) is applied after the through holes 3 are provided in the resin film 1, the conductive paste that has passed through the through holes 3 There is a risk of adhering to the printing plate and soiling the printing plate. Therefore, it is necessary to dispose a mount or the like on the one surface s1 of the resin film so as not to soil the plate surface.

Moreover, since the hole provided in the resin film 1 becomes the through-hole 3 that also penetrates the first conductive layer 2, the conductive paste for forming the second conductive layer 4 is the penetration formed in the first conductive layer 2. Since it was in contact with the first conductive layer 2 only at the cross section of the hole 3, the certainty of conduction was poor. Therefore, in practice, in order to increase the reliability of conduction, as shown in FIG. 7D, a conductive paste (first conductive layer) is applied again to the surface s1 on which the first conductive layer 2 is formed. The second conductive layer 4 exposed on the surface of the through hole 3 needs to be covered with the first conductive layer 2. Therefore, there has been a demand for this manufacturing method to eliminate the need for a mount or the like and to reduce the cost without performing the second coating of the first conductive layer 2.

Also, an example of manufacturing a circuit sheet using a copper foil without using a conductive paste is described in Japanese Patent Application Laid-Open No. 2003-036761 (Patent Document 2). However, the circuit sheet using copper foil is processed after the copper foil is bonded to the resin film, and then a resist pattern is applied, etching is performed, and the applied resist is removed to form a circuit pattern. There is a problem that the number of processes increases and the manufacturing cost increases.

JP 2007-214240 A JP 2003-036761 A

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a reliable conductive contact with respect to a circuit sheet in which circuit patterns are formed on both surfaces of a resin film and they are conductive. Moreover, it aims at provision of the circuit sheet which can be manufactured with few processes.

In order to achieve the above object, the present invention provides a circuit sheet having the following characteristics.

The present invention relates to a circuit sheet having a resin film, a first conductive layer formed on one side of the resin film, and a second conductive layer formed on the other side of the resin film. There is an opening through which the first conductive layer is exposed through the resin film, and the second conductive layer enters the inside of the opening from the other surface of the resin film and is exposed to the exposed portion of the first conductive layer. It has the indented part which carries out lamination | stacking and carries out electrical contact.

According to the present invention, as compared with the conventional technique, a plurality of

conductive layers

2 and 4 are laminated with a minute area about the inner peripheral surface of the through-hole 3 of the resin film 1 to obtain conductive contact. An indented portion of the second conductive layer can be stacked on the exposed portion of the first conductive layer that appears in the opening to make conductive contact. For this reason, the contact area between the indented portion and the first conductive layer can be increased, and a reliable and reliable contact contact can be realized.

The first conductive layer and the second conductive layer of the present invention can be a circuit pattern made of a printed layer. According to this, the circuit pattern of the 1st conductive layer of the 1st side of a resin film and the circuit pattern of the 2nd conductive layer of the other side can be comprised as a circuit sheet which carries out the conduction connection reliably in an intrusion part. Moreover, since it is a printed layer, a circuit sheet having a high degree of freedom in wiring can be easily realized with fewer man-hours than a circuit pattern formed by etching a copper foil as in the prior art.

The first conductive layer of the present invention can be a conductive printed layer in which conductive particles made of metal particles are dispersed in a binder. According to this, when the opening provided in the resin film is performed by laser processing, only the resin film can be penetrated and the first conductive layer can be prevented from penetrating. Therefore, the circuit sheet of the present invention having a structure in which the indented portion and the first conductive layer are laminated and brought into conductive contact with each other through the opening of the resin film can be manufactured with few steps.

The second conductive layer of the present invention can be a conductive printing layer in which conductive particles are dispersed in a binder. Since the second conductive layer is a printed layer, the solidified printed layer is formed along the shape of the hole in the resin film, and can be reliably laminated on the first conductive layer inside the hole.

The opening of the present invention may have a circular funnel shape that tapers from the other surface side toward the one surface side. If the opening is a hole surface perpendicular to the surface of the resin film, it is difficult to form a highly reliable second conductive layer there. However, in the present invention, the opening has a circular funnel shape. The indented portion of the second conductive layer can be reliably formed along the circular funnel-shaped hole surface.

In the present invention, the conductive contact surface between the indented portion and the first conductive layer can be a circuit sheet having a curved surface. According to this, compared with the case where a conduction contact surface is a plane, a contact area can be enlarged and a 1st conductive layer and a 2nd conductive layer can be made into conductive contact reliably.

The present invention can provide a circuit sheet in which the conductive contact surface between the indented portion and the first conductive layer is formed within the thickness range of the first conductive layer. According to this, since the indented portion of the second conductive layer comes into contact with the first conductive layer, the contact area between the first conductive layer and the second conductive layer is widened and reliable conductive contact is obtained. be able to.

The indented portion may be a circuit sheet having a tapered shape from the other side of the resin film toward the one side. According to this, the hole wall of the hole of a resin film can be reliably coat | covered with the coating liquid for 2nd conductive layers apply | coated from the said other surface side, and it can contact with a 1st conductive layer. Further, since the hole wall is inclined, the bubbles are easily removed, and the bubbles are less likely to remain at the leading edge of the indented portion than the vertical hole wall. Therefore, a circuit sheet with high reliability of conduction and high yield can be obtained.

The present invention can be a circuit sheet in which the surface of the first conductive layer is a flat surface. According to this, the 1st conductive layer with the flat surface can be easily obtained by apply | coating the coating liquid for 1st conductive layers to one side of a resin film.

The present invention may be a circuit sheet in which the proportion of conductive particles in the first conductive layer is 85% by mass or more. Thus, when the ratio of the conductive particles in the first conductive layer is 85% by mass or more, the step of leaving the first conductive layer while penetrating the resin film when opening a hole in the resin film with a laser. Easy to do. Therefore, it is easy to manufacture a circuit sheet having an indented portion that leaves the first conductive layer while reliably removing the resin film.

Furthermore, the present invention can provide a circuit sheet in which the proportion of conductive particles in the first conductive layer is 88% by mass or more. In the step of leaving the first conductive layer while penetrating the resin film when opening a hole in the resin film with a laser, the ratio of the conductive particles in the first conductive layer is 88% by mass or more. The width of output adjustment can be widened, and it is easier to manufacture a circuit sheet having an indented portion that leaves the first conductive layer while reliably removing the resin film.

The present invention can provide a circuit sheet in which the first conductive layer has a thickness of 2 to 20 μm and the resin film has a thickness of 10 to 200 μm. Since the thickness of the first conductive layer is 2 to 20 μm and the thickness of the resin film is 10 to 200 μm, the thickness of the resin film can be various from thin to thick compared to the thickness of the first conductive layer. It can be used as a circuit sheet according to the application.

In order to achieve the above object, the present invention provides a step of forming a first conductive layer to be a circuit pattern on one surface of a resin film, and a laser is irradiated from the other surface of the resin film, leaving the first conductive layer. A step of opening a taper-shaped opening in the resin film, and a second conductive layer that forms a circuit pattern having a recess that enters the opening and is in electrical contact with the first conductive layer on the other surface of the resin film. A method of manufacturing a circuit sheet for performing the steps is provided.

conductive layers

2 and 4 are laminated with a minute area about the inner peripheral surface of the through-hole 3 of the resin film 1 to obtain conductive contact. An indented portion of the second conductive layer can be stacked on the exposed portion of the first conductive layer that appears in the opening to make conductive contact. For this reason, the contact area between the indented portion and the first conductive layer can be increased, and a reliable and reliable contact contact can be realized. In addition, the number of steps for manufacturing a circuit sheet is smaller than that of the prior art, and the circuit sheet can be manufactured at a low cost.

The present invention may be a manufacturing method in which the first conductive layer and the second conductive layer are formed by printing. Since the first conductive layer and the second conductive layer are formed by printing, a circuit sheet with a high degree of freedom of wiring can be realized easily with less man-hours compared to a circuit pattern formed by etching copper foil as in the prior art. it can.

In the present invention, the first conductive layer may be formed by applying a conductive paste in which conductive particles made of metal particles are dispersed in a binder. According to this, when the opening provided in the resin film is performed by laser processing, only the resin film can be penetrated and the first conductive layer can be prevented from penetrating. Therefore, the circuit sheet of the present invention having a structure in which the indented portion and the first conductive layer are laminated and brought into conductive contact with each other through the opening of the resin film can be manufactured with few steps.

In the present invention, the second conductive layer may be formed by applying a conductive paste in which conductive particles are dispersed in a binder. Since the second conductive layer is a printed layer, the solidified printed layer is formed along the shape of the hole in the resin film, and can be reliably laminated on the first conductive layer inside the hole.

In the present invention, the laser can be a carbon dioxide laser. Since the laser is a carbon dioxide laser, it is easy to execute the process of leaving the conductive layer including the resin portion without removing it. Therefore, a complicated circuit pattern can be easily formed by a simple method of applying a conductive coating liquid in forming the conductive layer.

The present invention provides a circuit sheet in which the ratio of conductive particles in the first conductive layer is 85% by mass or more, the thickness of the first conductive layer is 2 to 20 μm, and the thickness of the resin film is 10 to 200 μm. It can be set as a manufacturing method. According to this, even if it is a circuit sheet of the structure where the thickness of a 1st conductive layer is thin compared with the thickness of a resin film, and it is difficult to manufacture with a YAG laser etc. with a low metal content rate, manufacture is easy.

According to the circuit sheet and the method for producing a circuit sheet of the present invention, the first conductive layer and the second conductive layer formed on both surfaces of the resin film can be reliably brought into conductive contact. In addition, a circuit sheet in which circuit patterns are formed on both surfaces of a resin film and the circuit patterns on both surfaces are reliably conducted can be easily manufactured with fewer steps than in the prior art.

It is a schematic cross section of the circuit sheet by one Embodiment. It is a schematic cross section of a circuit sheet according to another embodiment, a part (A) is a diagram showing a circuit sheet provided with a protective layer on the second conductive layer, and a part (B) shows the first conductive layer and the first conductive layer. It is a figure which shows the circuit sheet which provided the protective layer in the 2 conductive layer. It is explanatory drawing which shows the manufacturing process of a circuit sheet, A part (A) is a figure which shows the state which formed the 1st conductive layer in the resin film, A part (B) shows the state which formed the hole by the laser FIG. 6C is a diagram showing a state in which the second conductive layer is formed. It is a top view which shows the circuit pattern provided as a 1st conductive layer. It is a top view which shows the circuit pattern provided as a 2nd conductive layer. It is a figure which shows the overlapping state of the circuit pattern provided as a 1st conductive layer, and the circuit pattern provided as a 2nd conductive layer. It is a figure which shows the manufacturing process of the circuit sheet of a prior art.

Embodiments of the present invention will be described in more detail with reference to the drawings. Note that in various modified embodiments, the description of the overlapping portions of common materials, manufacturing methods, effects, and the like is omitted.

FIG. 1 shows a circuit sheet 10 of the present embodiment. The circuit sheet 10 is formed on the resin film 11, the first conductive layer 12 formed on the lower surface s <b> 1 serving as “one surface” of the resin film 11, and the upper surface s <b> 2 serving as the “other surface” of the resin film 11. And a second conductive layer 13. The resin film 11 has an opening 14 that penetrates the resin film 11, and the second conductive layer 13 has an indented portion 15 that enters the opening 14. The first conductive layer 12 and the second conductive layer 13 form a conductive contact portion 16 where the indented portion 15 contacts the first conductive layer 11.

Thus, the indented portion 15 of the second conductive layer 13 can be laminated and brought into conductive contact with the exposed portion of the first conductive layer 12 that appears in the opening 14 of the resin film 11. For this reason, compared with the conventional technique, a plurality of

conductive layers

2 and 4 are laminated with a minute area about the inner peripheral surface of the through-hole 3 of the resin film 1 to obtain conductive contact, and the indented portion 15 and the first The contact area with the conductive layer 12 can be widened, and the circuit sheet 10 capable of realizing reliable and reliable contact contact can be obtained.

The resin film 11 is a highly transparent resin film, for example, polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, polycarbonate (PC) resin, polyimide (PI) resin, methacrylic (PMMA) resin, Polypropylene (PP) resin, polyurethane (PU) resin, polyamide (PA) resin, polyethersulfone (PES) resin, polyetheretherketone (PEEK) resin, triacetylcellulose (TAC) resin, cycloolefin polymer (COP) Etc. can be formed.

As the resin film 11, use is made of a primer layer that improves adhesion to the conductive paste, a surface protective layer, an overcoat layer for the purpose of preventing static charge, or the like, which has been subjected to a surface treatment made of an organic polymer. Also good.

The thickness of the resin film 11 is preferably 10 to 200 μm. If the thickness is up to 200 μm, the strength as the circuit sheet 10 is satisfied, and as the thickness exceeds 200 μm, it is less necessary to increase the strength, and the space in the thickness direction is reduced. Moreover, since the thickness of the resin film 11 will become too thick compared with the thickness of the 1st conductive layer 12 mentioned later when exceeding 200 micrometers, when processing using a laser, the 1st conductive layer 12 is left and resin is left. It becomes difficult to adjust the laser output for removing the film 11. On the other hand, if it is less than 10 μm, the durability as a substrate may be insufficient.

The first conductive layer 12 is a conductive layer in which conductive particles made of metal particles are dispersed in a binder. Since conductive paste (conductive coating liquid) in which conductive particles made of metal particles are dispersed in a binder can be printed to form a circuit pattern, it is more than a circuit pattern formed by etching a copper foil as in the prior art. There is an advantage that the circuit sheet 10 having a high degree of wiring freedom can be manufactured at a low cost with a small number of steps.

As the conductive particles, particles made of metal can be used, and specifically, silver, copper, aluminum, nickel, alloys thereof, or particles coated with silver or gold can be given. Among these, silver particles having high conductivity and weather resistance are preferably used. In order to form the conductive contact portion 16 without removing the first conductive layer 12 in the laser treatment described later, such metal particles are preferable. In contrast, conductive particles obtained by coating a resin with a metal are difficult to use because they are easily removed by a laser.

An organic polymer can be used as the binder. Specific examples include various resins such as acrylic, epoxy, polyester, polyurethane, phenol resin, melamine resin, silicone, polyamide, polyimide, and polyvinyl chloride. Among these, polyester is preferable.

The conductive particles are dispersed in the binder, and the larger the proportion of the conductive particles in the total mass of the conductive particles and the binder, the larger the proportion of the conductive particles in the resin film 11 with the laser. It becomes difficult to remove the layer 12. Therefore, the proportion of the conductive particles in the first conductive layer 12 is preferably 85% by mass or more, and more preferably 88% by mass or more. If it is less than 85% by mass, it is difficult to produce by a production method using a carbon dioxide laser. Further, if it is 85% by mass or more, even if the thickness of the first conductive layer 12 is as thin as 4 to 20 μm, the first conductive layer 12 is not penetrated while the opening 14 is formed in the resin film 11. It can be left. If it is 88 mass% or more, the resin film 11 can be reliably removed regardless of the thickness of the resin film 11, and a part thereof can be left without penetrating the first conductive layer 12.

The upper limit of the ratio of the conductive particles to the total weight of the conductive particles and the binder is about 96% by mass. If it exceeds 96 mass%, the binder cannot hold the conductive particles, and the first conductive layer 11 may become brittle.

The thickness of the first conductive layer 12 can be 2 to 50 μm. Further, it is preferably 4 to 20 μm. If it is less than 2 μm, it may be removed together with the resin film 11 by laser during laser processing. If it exceeds 50 μm, the amount of conductive paste used increases, resulting in an increase in cost. If the thickness is 4 μm or more, the condition range of the laser output is widened and the manufacture becomes easy. Further, if the thickness is 20 μm or less, a step between the circuit pattern formed by the first conductive layer 12 and the surface of the resin film 11 around the first conductive layer 12 becomes small, and a protective layer 17 or the like is further provided on the circuit pattern. It is possible to suppress the mixing of bubbles during application.

The first conductive layer 12 can be formed by printing the conductive paste in a desired circuit pattern shape. The conductive paste can be obtained by (1) dissolving conductive particles and a binder in a solvent, (2) dissolving conductive particles and a binder precursor (main agent and curing agent) in a solvent, or (3) a binder precursor. When the body is in a liquid state, it is possible to use a binder precursor in which conductive particles are dispersed. In addition to the above components, a dispersant, an antifoaming agent, an ultraviolet absorber, an antioxidant, and the like may be added as appropriate to the conductive paste.

The second conductive layer 13 is a conductive layer made of a conductive material in which a conductive polymer or conductive particles are dispersed in a binder. As a material used for the second conductive layer 13, for example, a polythiophene-based conductive polymer or a material used for the first conductive layer 12 can be used. The conductive particles dispersed in the second conductive layer 13 are not limited to metal particles, and may be non-metallic conductive particles such as carbon.

The thickness of the second conductive layer 13 can also be 2 to 50 μm, and preferably 6 to 20 μm. If the thickness is less than 2 μm, the conductivity may be deteriorated. If the thickness exceeds 50 μm, the amount of the conductive paste used increases, resulting in an increase in cost. Further, if the thickness is 6 μm or more, the conductive paste is surely intruded into the opening of the resin film and it is difficult to cause poor conduction. If the thickness is 20 μm or less, the circuit pattern and the resin film The step at the boundary with the surface is reduced, and mixing of bubbles when applying a later-described protective layer 17 or the like on the circuit pattern can be suppressed.

The circuit sheet of the present invention requires the above-described configuration, but may include other elements as necessary. As shown in FIG. 2, for example, a protective layer 17 may be further stacked in addition to the first conductive layer 12 and the second conductive layer 13. The protective layer 17 may be laminated on the second conductive layer 13 (see FIG. 2A), may be laminated on the first conductive layer 12, or may be laminated on both the

conductive layers

12 and 13. (See FIG. 2B). By providing the protective layer 17, durability and weather resistance of the coated

conductive layers

12 and 13 can be enhanced.

The manufacturing method of the circuit sheet 10 will be described with reference to the drawings.

First, as a first step, as shown in FIG. 3A, a conductive paste in which conductive particles made of metal particles are dispersed in a binder on the lower surface s1 of the resin film 11 (first conductive layer coating solution). Is applied to form the first conductive layer 12. As a second step, as shown in FIG. 3B, a laser is irradiated from the upper surface s2 of the resin film 11, and the opening 14 having a tapered shape is formed in the resin film 11 leaving the first conductive layer 12. . Then, as a third step, as shown in FIG. 3C, a conductive paste (second conductive layer coating liquid) in which conductive particles are dispersed in a binder is applied to the upper surface s2 of the resin film 11. Thus, the recessed portion 15 having the conductive contact portion 16 in contact with the first conductive layer 12 is formed. Thus, the circuit sheet 10 can be manufactured.

Moreover, when forming the protective layer 17, it can form by apply | coating the coating liquid for protective layers 17 to a desired place after these processes, However, It protects on the lower surface s1 which provided the 1st conductive layer 12. When the layer 17 is provided, the protective layer 17 may be formed before the opening 14 is formed.

Examples of the method for applying the first conductive layer coating liquid and the method for applying the second conductive layer coating liquid in the first step include screen printing, bar coating, and dispenser application. Among them, it is particularly preferable to employ screen printing in that relatively detailed and complicated circuit patterns can be formed at low cost.

The laser used in the second step is preferably a carbon dioxide laser. With a solid laser such as a YAG laser or a fiber laser, the first conductive layer 12 is easily removed along with the removal of the resin film 11, and it is difficult to remove only the resin film 11 while leaving the first conductive layer 12. On the other hand, according to the carbon dioxide laser, it is possible to easily perform the process of leaving the thin first conductive layer 12 while penetrating the thick resin film 11.

Further, when the carbon dioxide laser is used, the shape of the hole to be opened is circular, and the opening 14 having a tapered shape that becomes thinner toward the tip can be formed. Opening with a drill or the like is a hole having a uniform diameter, and it is difficult to coat the inner peripheral surface of the hole with the coating liquid for the second conductive layer. In contrast, if the opening 14 has a tapered shape, the coating liquid for the second conductive layer can be easily attached along the circular funnel-shaped hole wall surface of the opening 14 in the third step, and has a constant layer thickness. The insertion portion 15 can be formed, and reliable conduction can be achieved. If such a manufacturing method is employ | adopted, the number of processes can be decreased compared with a prior art, and the circuit sheet 10 can be manufactured at low cost.

A concave surface 12a is formed in the first conductive layer 12 by being irradiated with the carbon dioxide gas laser. Then, the indented portion 15 of the second conductive layer 13 is formed so as to be in contact with the concave surface 12 a, so that the curved conductive contact portion 16 is formed within the thickness range of the first conductive layer 12. The curved conductive contact portion 16 can have a wider contact area than the planar contact portion 16. Moreover, even if it enters in the thickness range of the 1st conductive layer 12, the contact area can be made wider than the case where it does not enter. Therefore, reliable conductive contact between the first conductive layer 12 and the second conductive layer 13 can be obtained.
In addition, about the said concave surface 12a formed in the curved surface shape, after forming the 2nd conductive layer 13, the surface of the 2nd conductive layer 13 also becomes a curved surface shape. Therefore, when the cross section of the conduction contact portion 16 is observed, it can be observed that the thickness of the center is thinner than the peripheral portion of the conduction back portion 16.

In addition, a laser mark region having a different color from the surroundings is formed in the first conductive layer 12 by irradiation with a carbon dioxide laser. The region having a different color is a region in which the first conductive layer 12 has changed in quality and the color has changed, and is formed when the resin film 11 is completely penetrated. Therefore, it can be used for quality confirmation after irradiating a carbon dioxide laser by confirming such a region.

The above embodiment is an example of the present invention, and the present invention is not limited to such a form. The shape, material, manufacturing method, and the like of each member can be changed or replaced within the scope not departing from the gist of the present invention. is there.

The following various “circuit sheet” samples in which the first conductive layer 12 was provided on the back surface of the resin film 11 and the second conductive layer 13 was provided on the front surface were manufactured, and the conduction performance was evaluated. In the following description, the notation of the front and back surfaces of the resin film is for convenience.

<Preparation of sample>
Tables 1 and 2 in which a polyethylene terephthalate film having a thickness of 100 μm as a transparent resin film and irregularly shaped silver particles having a particle diameter of 3 to 5 μm as a first conductive layer coating liquid are dispersed in a polyester resin composition are shown in Tables 1 and 2 The same silver paste 1 to silver paste 4 as those for the silver paste 1 were prepared as the second conductive layer coating solutions.

The first conductive layer having a thickness of 7 μm composed of the wiring pattern 12a shown in FIG. 4 was formed on the back surface of the resin film by applying a coating liquid for the first conductive layer and drying it. The wiring pattern 12a of the first conductive layer includes 20 pieces of circles having a diameter of 0.8 mm with a spacing of 2.2 mm, and 3.0 mm square terminals with a spacing of 1.1 mm from both outer circles. The two circles or the outer circles and the terminals are connected by a straight line having a line width of 0.5 mm.

Next, a carbon dioxide laser was applied to the position corresponding to the center of the 20 circles of the wiring pattern 12a from the surface of the resin film opposite to the surface on which the wiring pattern 12a was formed. ML-Z9520 (manufactured by Keyence Corporation) was used as the laser, and irradiation conditions were as shown in Tables 1 and 2.

Then, a second conductive layer coating liquid was applied to the surface of the resin film by screen printing and dried to form a second conductive layer having a thickness of 7 μm composed of a printed layer of the wiring pattern 13a shown in FIG. The wiring pattern 13a of the second conductive layer has a circle with a diameter of 0.8 mm at a position overlapping the circle of the wiring pattern 12a of the first conductive layer, and the two circles are connected by a straight line having a line width of 0.5 mm. The configuration. Then, the wiring pattern 12a shown in FIG. 6 is formed between the wiring pattern 12a of the first conductive layer and the wiring pattern 13a of the second conductive layer with a transparent resin film interposed therebetween. In the wiring pattern 18, if the first conductive layer and the second conductive layer are in contact with each other at a circle to form a conductive contact portion, the two terminals are electrically connected.

As the coating liquid for the first conductive layer shown in Table 1, the ratio of the conductive particles in the dry mass of the “silver paste 1” is 88% by mass, and the “silver paste 2” is in the dry mass. The ratio of the conductive particles is 85% by mass, “silver paste 3” has the ratio of the conductive particles in its dry mass of 79% by mass, and “silver paste 4” has the conductivity in its dry mass. The ratio of the particles is 65% by mass, and the “resin ink” is a binder made of a polyester resin that does not disperse the conductive particles.

Further, as the carbon dioxide laser irradiation conditions shown in Table 1, “Condition 1” is laser output 50 and scan speed 200 mm / s, and “Condition 2” is laser output 40 and scan speed 200 mm / s. "Condition 3" is laser output 30 and scan speed 200 mm / s, and "Condition 4" is laser output 20 and scan speed 200 mm / s.
A preliminary experiment was conducted in which the resin film before forming the first conductive layer was irradiated with a carbon dioxide laser according to each of conditions 1 to 4, and the size of the openings formed in the resin film was observed. did. The diameters of the apertures measured through the optical microscope from the front side and the back side of the resin film are shown in Table 3 below. The opening formed by the irradiation of the carbon dioxide laser had a tapered circular funnel-shaped hole wall surface.

<Sample evaluation method>
Formation of through holes in resin film :
As shown in Table 3, with regard to the laser irradiation conditions, in condition 4 where the output is 20, no through hole is formed, and even in condition 3 where the output is 30, the diameter of the opening is extremely 0.07 mm. It became small. On the other hand, in

conditions

1 and 2, an opening having a tapered cross section was formed in the resin film, and a hole having a diameter exceeding 0.1 mm was formed even on the back surface of the tapered resin film.

About formation of conductive contact part:
Except for the sample 7 where it is clear that no opening is formed in the resin film and a conductive contact portion is not obtained, the second conductive layer enters the opening formed in the resin film for the other samples. In order to determine whether or not a conductive contact portion was formed in contact with the layer, first, the back surface of each sample was observed with an optical microscope as to whether or not the first conductive layer penetrated. And what the 1st conductive layer did not penetrate was made into "penetration pear", and what penetrated was made into "with penetration." And about the sample which the 1st conductive layer penetrated and was "with penetration", the diameter of the hole formed in the 1st conductive layer was measured. These results are shown in Tables 1 and 2.

Continuity evaluation:
The resistance value between the terminals at both ends of the wiring pattern 18 shown in FIG. 6 of each sample was measured with a tester. The measurement results are shown in Tables 1 and 2.

<Evaluation results>
In the sample 1 in which the metal content of the first conductive layer is 88% by mass, the first conductive layer does not penetrate and the resistance value is low regardless of whether the laser irradiation condition is the condition 1 or the condition 2. It can be seen that a conductive contact portion in which the conductive layer and the second conductive layer are in contact is formed. On the other hand, in Sample 2 in which the metal content in the first conductive layer was 85% by mass, a conductive contact portion was formed when the laser irradiation condition was Condition 2, whereas in Condition 1, the first conductive layer penetrated. have done. From this, it is necessary to carefully set the laser output in the sample 2, and it can be understood that the conduction contact portion can be formed by the carefully set output.

Furthermore, in the

samples

3 and 4 having a lower metal content, the first conductive layer penetrated, and no conductive contact portion was formed. Comparing the diameters of the apertures of the first conductive layer generated in the sample 3 and the sample 4, the sample 4 is larger than the sample 3, and as a result, the smaller the proportion of the metal content in the first conductive layer is, It can be seen that holes are more likely to open in the first conductive layer, and conversely, holes are less likely to open in the first conductive layer as the metal content in the first conductive layer increases.

Further, in the sample 6 having a laser output with a small hole having a diameter of 0.07 mm in the resin film, the second conductive layer was not conductive because no opening was formed in the first conductive layer. It is considered that the coating liquid for coating does not sufficiently enter the inside of the openings of the resin film, and the coating liquid for the second conductive layer does not reach the surface of the first conductive layer.

Industrial applicability

The circuit sheet of the present invention can be used for various purposes. For example, a flexible circuit board, a touch sensor, other sensors, electroluminescence, and the like can be mentioned, but the invention is not limited thereto.

1 Resin film s1 Bottom (one side)
s2 Upper surface (the other surface)
DESCRIPTION OF SYMBOLS 2 1st conductive layer 3 Through-hole 4 2nd conductive layer 5 Conductive path 10 Circuit sheet 11 Resin film 12 1st conductive layer 12a Concave surface 12b Wiring pattern 13 2nd conductive layer 13a Wiring pattern 14 Opening 15 Intrusion part 16 Conducting contact part (Conduction contact surface)
17 Protective layer 18 Wiring pattern

Claims

In a circuit sheet having a resin film, a first conductive layer formed on one side of the resin film, and a second conductive layer formed on the other side of the resin film,
The resin film has an opening that penetrates the resin film and exposes the first conductive layer on the other surface;
The circuit sheet, wherein the second conductive layer has an indented portion that enters the inside of the opening from the other surface of the resin film and is laminated and exposed to the exposed portion of the first conductive layer.
The circuit sheet according to claim 1, wherein the first conductive layer and the second conductive layer are a circuit pattern formed of a printed layer.
The circuit sheet according to claim 1, wherein the opening has a circular funnel shape that tapers from the other surface side toward the one surface side.
The circuit sheet according to any one of claims 1 to 3, wherein a conductive contact surface between the indented portion and the first conductive layer is within a thickness range of the first conductive layer.
The circuit sheet according to any one of claims 1 to 4, wherein the indented portion has a tapered shape from the other surface side to the one surface side of the resin film.
6. The first conductive layer according to claim 1, wherein conductive particles made of metal particles are dispersed in a binder, and a ratio of the conductive particles in the first conductive layer is 85% by mass or more. The circuit sheet as described.
The circuit sheet according to any one of claims 1 to 6, wherein the first conductive layer has a thickness of 2 to 20 µm, and the resin film has a thickness of 10 to 200 µm.
Forming a first conductive layer to be a circuit pattern on one surface of the resin film;
Irradiating a laser from the other side of the resin film, leaving a first conductive layer and opening a taper-shaped opening in the resin film; and
A method of manufacturing a circuit sheet, comprising: forming a second conductive layer that forms a circuit pattern having an indented portion that enters the opening and is in conductive contact with the first conductive layer on the other surface of the resin film.
The method for manufacturing a circuit sheet according to claim 8, wherein the first conductive layer is formed by applying a conductive paste in which conductive particles made of metal particles are dispersed in a binder.
The method for producing a circuit sheet according to claim 8 or 9, wherein the laser is a carbon dioxide gas laser.
The ratio of the conductive particles in the first conductive layer is 85% by mass or more, the thickness of the first conductive layer is 2 to 20 μm, and the thickness of the resin film is 10 to 200 μm. A method for producing a circuit sheet according to claim 1.