TW201942215A - Carrier film for conductive adhesive layer and bonding film having the same hardly forgetting about peeling of a carrier film and implementing alignment easily - Google Patents

Abstract

This invention aims to provide a carrier film for conductive adhesive layer that hardly forgets about peeling of a carrier film, and also can implement alignment easily. The carrier film for a conductive adhesive layer is provided on the surface of a conductive adhesive layer and has a total light transmittance of 30% or more and 80% or less, and [Delta]E*ab of the conductive adhesive layer is 20 or more, and the L* value is 40 or more and 70 or less.

Description

Carrier film for conductive adhesive layer and adhesive film provided with the same

The present invention relates to a carrier film and an adhesive film for a conductive adhesive layer.

BACKGROUND ART When a reinforcing plate is mounted on a flexible printed wiring board or the like, a conductive adhesive film laminated with a conductive adhesive layer and a carrier film is used. When installing a reinforcing plate, first, a conductive adhesive film cut into a predetermined shape is fixed to a predetermined position on a flexible printed wiring board. Then, the carrier film is removed, and the reinforcing plate is bonded with a conductive adhesive.

In order to prevent forgetting to remove the carrier film, measures are taken to make the carrier film opaque or increase the haze value (for example, refer to Patent Document 1).

Advance technical literature
[Patent Literature]
[Patent Document 1] Japanese Patent Laid-Open No. 2005-294294

Summary of the Invention Problems to be Solved by the Invention On the other hand, when a conductive adhesive film is fixed to a plurality of positions of a flexible printed wiring board, if a carrier film is left, only a conductive adhesive layer is cut through and patterned By being formed into a predetermined shape, the conductive adhesive film can be fixed to a plurality of positions of the flexible printed wiring board at one time. In this case, when the conductive adhesive film is fixed to the flexible printed wiring board, it is important to accurately grasp the position of the conductive adhesive layer so that alignment can be performed. In order to correctly align, it is better to detect the edge position of the conductive adhesive layer through a carrier film. However, in the case of a film having a high haze value with improved visibility, the edge position is blurred and difficult to detect correctly. s position.

Such a problem occurs not only in a conductive adhesive film but also in various substrate materials having a conductive adhesive layer provided with a carrier film.

The object of the present invention is to make it possible not only to make it difficult to forget the peeling of the carrier film, but also to easily recognize the carrier film for the conductive adhesive layer of the lower layer.

Solution to Problem One aspect of the carrier film for a conductive adhesive layer of the present invention is provided on the surface of the conductive adhesive layer. The total light transmittance of the carrier film for the conductive adhesive layer is 30% or more and 80% or less, and the color difference (ΔE _ab *) from the conductive adhesive layer is 20 or more.

In one aspect of the carrier film for a conductive adhesive layer, the L * value of the conductive adhesive layer may be 40 or more and 70 or less.

One aspect of the adhesive film of the present invention includes a carrier film for a conductive adhesive layer of the present invention.

ADVANTAGE OF THE INVENTION According to the carrier film for conductive adhesive layers of this invention, it is not only difficult to forget the peeling of a carrier film, but also an easy identification of a lower layer.

The form for implementing the invention is shown in FIG. 1. The carrier film 112 for the conductive adhesive layer of this embodiment is provided on the surface of the conductive adhesive layer 111 in the adhesive film 100 having the conductive adhesive layer 111.

As shown in FIG. 2, the conductive adhesive film 100 according to this embodiment can only be partially cut through the conductive adhesive layer 111 using a stamping mold or the like, and then temporarily fixed to a predetermined position of the printed wiring board 200 after being punched into a predetermined pattern. At this time, while the position of the patterned conductive adhesive layer 111 is confirmed by the carrier film 112, it is aligned to a desired position of the printed wiring board. Then, the carrier film 112 is peeled off, a reinforcing plate or the like is placed on the conductive adhesive layer 111, and then pressure / heating is performed, whereby the printed wiring board 200 and the reinforcing plate can be bonded and conducted.

In order to facilitate the alignment of the conductive adhesive layer 111, it is desirable to increase the total light transmittance of the carrier film 112 so that the position of the conductive adhesive layer 111 can be easily grasped. On the other hand, in order to prevent the carrier film 112 from being stripped, it is desirable to reduce the total light transmittance of the carrier film 112 and improve visibility. In general, the total light transmittance of the film of the lower layer can be easily identified to be at least about 70% to 80%, and it can be easily confirmed that the total light transmittance of the existing film is only about 20%. However, the inventors have found that by controlling the total light transmittance of the carrier film 112 and simultaneously controlling the color difference (ΔE * _ab ) from the lower layer, it is possible to have both the ease and discrimination of grasping the position of the lower layer.

In the conductive adhesive film 100 of the present invention, the total light transmittance of the carrier film 112 is 30% or more, preferably 45% or more and 80% or less, and preferably 75% or less. ΔE * _ab is 20 or more, preferably 30 or more, and more preferably 33 or more. The larger ΔE * _ab is, the better, but in terms of the actual range of color adjustment, it is preferably 60 or less, preferably 50 or less, and more preferably 39 or less.

Thereby, the conductive adhesive layer 111 patterned by punching can be easily recognized from the supporting film side, and its position can be accurately grasped. Thereby, the patterned conductive adhesive layer 111 can be correctly aligned and can be temporarily fixed to the printed wiring board 200.

In addition, by setting the total light transmittance and ΔE * _ab to predetermined values, the visibility of the carrier film 112 is also increased, and it is not easy to forget to peel off the carrier film 112 after being temporarily fixed.

In the carrier film 112 of this embodiment, the L * value of the lower conductive adhesive layer 111 is preferably 40 or more, more preferably 50 or more, and preferably 70 or less, and more preferably 60 or less. The visibility of the conductive adhesive layer 111 and the carrier film 112 is improved.

In addition, the total light transmittance of the carrier film 112, the ΔE _ab * of the carrier film 112 and the conductive adhesive layer 111, and the L * value of the conductive adhesive layer 111 can be measured by the methods shown in the examples.

As long as the total light transmittance of the carrier film 112 and ΔE _ab * with respect to the conductive adhesive layer 111 satisfy predetermined values, regardless of the material, for example, a thermoplastic resin composition, a thermosetting resin composition, and an active energy ray can be used for curing. Sex composition. As such a resin composition, polyester, polyolefin, polyimide, polyphenylene sulfide, etc. can be used, for example. In order to adjust the total light transmittance, various additives may be added to these resins. The additive is not particularly limited, and pigments or dyes can be used. Examples of the pigment include organic pigments and inorganic pigments.

Specific examples of the organic pigment include insoluble azo pigments such as toluidine red, toluidine purple red, lufthansa yellow, benzidine yellow, and pyrazolinone red; rissol red, too red (Helio Bordeaux), and scarlet Pigment (pigment scarlet) and soluble red 2B (permanent red) and other soluble azo pigments; Derivatives derived from vat dyes such as alizarin, indanthrene and thioindigo maroon; phthalocyanines such as phthalocyanine blue and phthalocyanine green Organic pigments; quinacridone organic pigments such as quinacridone red and quinacridone magenta; fluorene-based organic pigments such as perylene red and saffron; isoindolinone yellow and isoindolinone orange Indoline organic pigments; Pyranthrone Red and Pyranthrone Orange and other anthracene organic pigments; thioindigo organic pigments; condensed azo organic pigments; benzimidazolone organic pigments Pigments; quinoline organic pigments such as Quinophthalone Yellow; isoindoline organic pigments such as isoindoline yellow; and other pigments include Flavanthrone Yellow, pyramine yellow, and nickel Nitrogen yellow, copper methylimide yellow, purple ring orange, anthrone , Two red and two anthraquinone Purple and so on.

Specific examples of the inorganic pigment include silicon dioxide, aluminum oxide, titanium oxide, barium sulfate, calcium carbonate, zinc oxide, lead sulfate, yellow lead, zinc yellow, and rouge (red iron (III) oxide), Cadmium red, ultramarine blue, Prussian blue, chrome oxide green, cobalt green, amber, titanium black, and synthetic iron black.

As for the dye, various previously known compounds can be used.

A release agent layer (not shown) may be provided between the carrier film 112 and the conductive adhesive layer 111. The release agent layer can be formed by applying a silicon-based or non-silicon-based release agent to the surface of the conductive adhesive layer 111 side of the carrier film 112. When the release agent layer is formed, the thickness may be several μm to several 10 μm.

In this embodiment, the conductive adhesive layer 111 includes a resin component such as a thermoplastic resin and a thermosetting resin, and a conductive filler.

When the conductive adhesive layer 111 contains a thermoplastic resin, the thermoplastic resin may be, for example, a styrene resin, a vinyl acetate resin, a polyester resin, a polyethylene resin, a polypropylene resin, a fluorene resin, or Acrylic resin, etc. These resins may be used singly or in combination of two or more kinds.

When the conductive adhesive layer 111 contains a thermosetting resin, the thermosetting resin can be, for example, a phenol-based resin, an epoxy-based resin, a urethane-based resin, a melamine-based resin, a polyamide-based resin, and an alcohol. Acid-based resins, etc. The active energy ray-curable composition is not particularly limited, but for example, a polymerizable compound having at least two (meth) acryloxy groups in a molecule can be used. These compositions may be used singly or in combination of two or more kinds.

The thermosetting resin includes, for example, a first resin component having a reactive first functional group and a second resin component that reacts with the first functional group. The first functional group may be, for example, an epoxy group, amidino group, or a hydroxyl group. The second functional group may be selected based on the first functional group. For example, when the first functional group is an epoxy group, the second functional group may be a hydroxyl group, a carboxyl group, an epoxy group, an amine group, or the like. Specifically, for example, when the first resin component is an epoxy resin, as the second resin component, epoxy-modified polyester resin, epoxy-modified polyamine resin, and epoxy-modified acrylic can be used. Resin, epoxy-modified polyurethane polyurea resin, carboxy-modified polyester resin, carboxy-modified polyamine resin, carboxy-modified acrylic resin, carboxy-modified polyurethane polyurea resin And urethane modified polyester resin. Among these, a carboxyl modified polyester resin, a carboxyl modified polyamine resin, a carboxyl modified polyurethane polyurea resin, and a urethane modified polyester resin are preferred. When the first resin component is a hydroxyl group, the second resin component can be used: epoxy-modified polyester resin, epoxy-modified polyamine resin, epoxy-modified acrylic resin, epoxy-modified Polyurethane polyurea resin, carboxyl modified polyester resin, carboxyl modified polyamido resin, carboxyl modified acrylic resin, carboxyl modified polyurethane polyurea resin, and urethane modified High quality polyester resin. Among these, a carboxyl modified polyester resin, a carboxyl modified polyamine resin, a carboxyl modified polyurethane polyurea resin, and a urethane modified polyester resin are preferred.

The thermosetting resin may contain a curing agent for promoting a thermosetting reaction. When the thermosetting resin has a first functional group and a second functional group, the curing agent can be appropriately selected depending on the types of the first functional group and the second functional group. When the first functional group is an epoxy group and the second functional group is a hydroxyl group, an imidazole-based hardener, a phenol-based hardener, or a cationic hardener can be used as the hardener. These may be used alone or in combination of two or more. In addition, as an optional component, a defoaming agent, an antioxidant, a viscosity adjusting agent, a diluent, an anti-settling agent, a leveling agent, a coupling agent, a coloring agent, and a flame retardant may be included.

The conductive filler is not particularly limited, and examples thereof include metal fillers, metal-coated resin fillers, carbon fillers, and mixtures thereof. Examples of the metal filler include copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. These metal powders can be produced by an electrolytic method, an atomization method, or a reduction method. Among them, any one of silver powder, silver-coated copper powder, and copper powder is preferred.

From the viewpoint that the fillers are in contact with each other, the average particle diameter of the conductive filler is preferably 1 μm or more, more preferably 3 μm or more, preferably 50 μm or less, and more preferably 40 μm or less. The shape of the conductive filler is not particularly limited, and may be formed into a spherical shape, a sheet shape, a dendritic shape, or a fibrous shape.

The content of the conductive filler can be appropriately selected according to the application. The total solid content of the conductive adhesive layer is preferably 5 mass% or more, more preferably 10 mass% or more, more preferably 95 mass% or less, and more preferably 90% by mass or less. From the viewpoint of landfillability, it is preferably 70% by mass or less, and more preferably 60% by mass or less. When anisotropic conductivity is achieved, it is preferably 40% by mass or less, and more preferably 35% by mass or less.

The conductive adhesive layer 111 can be formed, for example, by applying a composition for a conductive adhesive layer on the carrier film 112. The composition for a conductive adhesive layer can be prepared by adding an appropriate amount of a solvent to the resin and a filler for a conductive adhesive layer.

From the viewpoint of controlling the landfillability, the thickness of the conductive adhesive layer 111 is preferably 1 μm to 50 μm.

In addition, a peelable protective film may be laminated on the surface of the conductive adhesive layer 111 as necessary. In addition, a release agent layer or the like may be provided on both sides of the carrier film 112, and the carrier film 112 and the conductive adhesive layer 111 are alternately arranged to be wound.

The conductive adhesive film 100 of this embodiment can be temporarily fixed to the printed wiring board 200 after leaving the carrier film 112 and half-cutting the conductive adhesive layer 111 and patterning it. However, the carrier film 112 may be cut and patterned together with the conductive adhesive layer 111 and temporarily fixed to the printed wiring board 200. In this case, it is useful that the forgetting peeling of the carrier film 112 does not easily occur.

The carrier film 112 for the conductive adhesive layer of this embodiment can be used not only for a conductive adhesive film, for bonding a conductive reinforcing plate, a heat sink, etc. to a flexible printed wiring board, but also for conductive properties such as a shielding film. The carrier film of the adhesive layer.

[Example]
Hereinafter, the conductive adhesive film of the present invention will be described in more detail using examples. The following examples are illustrative and are not intended to limit the present invention.

＜ Production of conductive adhesive film ＞
A non-silicon release agent is coated on the surface of a predetermined carrier film to form a release agent layer. The thickness of the release agent layer was set to 0.1 μm. Then, the composition for a conductive adhesive layer was coated with a wire rod, and then dried at 100 ° C. for 3 minutes to form a conductive adhesive layer having a thickness of 60 μm to obtain a conductive adhesive film.

The composition for a conductive adhesive layer was prepared based on 55 parts by mass of a polyurethane polyurea resin having an acid value of 25 mgKOH / g, and 45 parts by mass of an epoxy resin. In addition, the composition of the epoxy resin is 20 parts by mass of a phenoxy-type epoxy resin (trade name jER4275, manufactured by Mitsubishi Chemical Corporation), 20 parts by mass of a phenol novolac epoxy resin (trade name jER152, manufactured by Mitsubishi Chemical Corporation), and rubber 5 parts by mass of modified epoxy resin (trade name ERP-4030, manufactured by Asahi Denka). This was hard-coated on the release-treated polyethylene terephthalate film using a doctor blade (plate-shaped spatula) and dried at 100 ° C for 3 minutes to prepare a conductive adhesive film. Moreover, the squeegee blade is appropriately selected from 1 mil to 5 mil products according to the thickness of the conductive adhesive film produced. Furthermore, 1 mil = 1/1000 inch = 25.4 μm. In each Example and each comparative example, it produced so that the thickness of a conductive adhesive film might become a predetermined thickness. The thickness of the conductive adhesive film was measured by a micrometer.

Moreover, silver powder (made by Fukuda Metal Foil Powder Industry Co., Ltd.) having an average particle diameter of 5 μm was used as the conductive filler.

＜ Measurement of total light transmittance ＞
The total light transmittance of the carrier film was measured in accordance with JIS K 7361 using a haze meter (manufactured by Nippon Denshoku Industries, Ltd., SH7000).

<Evaluation of L *>
The L * value of the conductive adhesive layer was measured using an integrating sphere spectrophotometer (X-Rite, Ci64, tungsten light source).

＜ Measurement of color difference ＞
The color difference (ΔE * _ab ) between the carrier film and the conductive adhesive layer was measured in accordance with CIE76 (delta E76) using an integrating sphere spectrophotometer (X-Rite, Ci64, tungsten light source).

＜ Discriminative evaluation ＞
Regarding the visibility of the carrier film, when the adhesive film is observed from the carrier film side, it can be visually confirmed that the presence of the carrier film is good (○), and when it cannot be confirmed, it is defective (×).

The visibility of the conductive adhesive layer was evaluated as follows. The carrier film is left, and a part of the conductive adhesive layer of the adhesive film is cut through to a square shape to form a square conductive adhesive layer. The partially cut adhesive film was placed on the polyimide film with the conductive adhesive layer facing downward, and it was visually confirmed whether the square conductive adhesive layer could be seen through the side of the carrier film. Specifically, when the four corners of the square conductive adhesive layer can be confirmed visually, it is good (○), and when the four corners of the square conductive adhesive layer cannot be visually confirmed, it is bad. (×).

(Example 1)
As a carrier film, a PET film having a thickness of 50 μm was used. The total light transmittance was 50%, and the L * value of the conductive adhesive layer was 51. The color difference (ΔE * _ab ) between the PET film and the conductive adhesive layer was 34. The visibility of the conductive adhesive layer from the carrier film side was good (○), and the visibility of the carrier film was also good (○).

(Example 2)
As a carrier film, a milky white PET film having a thickness of 55 μm was used. The total light transmittance was 65%, and the L * value of the conductive adhesive layer was 69. In addition, ΔE * _ab is 34. The visibility of the conductive adhesive layer from the carrier film side was good (○), and the visibility of the carrier film was also good (○).

(Example 3)
As a carrier film, a milky white PET film having a thickness of 50 μm was used. The total light transmittance was 46%, and the L * value of the conductive adhesive layer was 41. In addition, ΔE * _ab was 35. The visibility of the conductive adhesive layer from the carrier film side was good (○), and the visibility of the carrier film was also good (○).

(Comparative example 1)
As the carrier film, a white PET film having a thickness of 38 μm was used. The total light transmittance was 13%, and the L * value of the conductive adhesive layer was 60. In addition, ΔE * _ab was 40. Although the visibility of the conductive adhesive layer from the support film side was poor (×), the visibility of the support film was good (○).

(Comparative example 2)
As the carrier film, a white PET film having a thickness of 50 μm was used. The total light transmittance was 5%, and the L * value of the conductive adhesive layer was 55. In addition, ΔE * _ab is 32. Although the visibility of the conductive adhesive layer from the support film side was poor (×), the visibility of the support film was good (○).

(Comparative example 3)
As the carrier film, a transparent PET film having a thickness of 38 μm was used. The total light transmittance was 90%, and the L * value of the conductive adhesive layer was 53. In addition, ΔE * _ab was 2.9. Although the visibility of the conductive adhesive layer from the support film side was good (○), the visibility of the support film was poor (×).

The results of the examples and comparative examples are summarized in Table 1.

[Table 1]

INDUSTRIAL APPLICABILITY The carrier film for the conductive adhesive layer of the present invention is not only difficult to forget the peeling of the carrier film, but also allows easy identification of the underlying layer. For various substrate materials with a conductive adhesive layer It is useful.

100‧‧‧ conductive adhesive film

111‧‧‧ conductive adhesive layer

112‧‧‧bearing film

200‧‧‧printed wiring board

FIG. 1 is a cross-sectional view showing a conductive adhesive film including a carrier film for a conductive adhesive layer according to an embodiment.

2 is a cross-sectional view showing a state where a conductive adhesive film is fixed to a printed wiring board.

Claims (3)

A carrier film for a conductive adhesive layer is provided on the surface of the conductive adhesive layer. The total light transmittance of the carrier film for a conductive adhesive layer is 30% to 80%, and is the same as the conductive adhesive. The ΔE * _ab of the layer is 20 or more. The carrier film for a conductive adhesive layer according to claim 1, wherein the L * value of the conductive adhesive layer is 40 or more and 70 or less. A conductive adhesive film provided with a conductive carrier film according to claim 1 or 2.