TWI735811B - Carrying film for conductive adhesive layer and adhesive film with same - Google Patents

Abstract

The subject of the present invention is to realize a carrier film for a conductive adhesive layer that is not only difficult to forget to peel off the carrier film, but also can be easily aligned. The carrier film for the conductive adhesive layer of the present invention is provided on the surface of the conductive adhesive layer, the total light transmittance is 30% or more and 80% or less, and the ΔE* _ab with the conductive adhesive layer is 20 or more.

Description

Carrying film for conductive adhesive layer and adhesive film with same

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

Background technique

When mounting the reinforcing plate on the flexible printed wiring board, etc., a conductive adhesive film in which a conductive adhesive layer and a carrier film are laminated is used. When installing the reinforcing plate, first fix the conductive adhesive film that has been cut into a predetermined shape to a predetermined position on the flexible printed circuit board. Then, the carrier film is removed, and the reinforcing plate is bonded with the 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).

Advanced technical literature

[Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2005-294294

Summary of the invention

On the other hand, in the case of fixing the conductive adhesive film at multiple positions of the flexible printed wiring board, if the carrier film is left and only the conductive adhesive layer is half-pierced and patterned into a predetermined shape, it can be Conductivity The adhesive film is fixed on multiple positions of the flexible printed circuit board. At this time, when fixing the conductive adhesive film to the flexible printed wiring board, the key is to accurately grasp the position of the conductive adhesive layer so that the alignment can be performed. In order to correctly align, it is better to detect the edge position of the conductive adhesive layer through the carrier film. However, in the case of a film with a higher haze value with improved recognizability, the edge position is blurred and it is difficult to detect correctly. s position.

This problem occurs not only in conductive adhesive films, but also in various substrate materials with conductive adhesive layers provided with carrier films.

The subject of the present invention is to realize a carrier film for a conductive adhesive layer that is not only difficult to forget to peel off the carrier film, but also can be easily recognized in the lower layer.

One aspect of the carrier film for the conductive adhesive layer of the present invention is provided on the surface of the conductive adhesive layer, and 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 ) of the conductive adhesive layer is 20 or more.

In one aspect of the carrier film for the 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 is provided with the carrier film for the conductive adhesive layer of the present invention.

According to the carrier film for the conductive adhesive layer of the present invention, it is not only difficult to If the carrier film is forgotten to peel off, the lower layer can also be easily identified.

100: Conductive adhesive film

111: Conductive adhesive layer

112: Carrier film

200: Printed wiring board

FIG. 1 is a cross-sectional view of a conductive adhesive film provided with a carrier film for a conductive adhesive layer according to an embodiment.

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

The form used to implement the invention

As 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 of the present embodiment can be cut into a predetermined pattern by using a stamping die or the like to cut only the conductive adhesive layer 111 halfway, and then temporarily fixed to a predetermined position on the printed wiring board 200. At this time, while confirming the position of the patterned conductive adhesive layer 111 through the carrier film 112, alignment is performed to the 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 pressurization/heating is performed, so that the printed wiring board 200 and the reinforcing plate can be bonded together to make them conductive.

In order to facilitate the alignment of the conductive adhesive layer 111, it is preferable 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 forgetting to peel off, it is advisable to reduce the total light transmittance of the carrier film 112 and improve the identification. Generally speaking, the total light transmittance of the film of the lower layer can be easily recognized is 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% at most. However, the inventors of the present case found that by controlling the total light transmittance of the carrier film 112 and the chromatic aberration (ΔE* _ab ) from the lower layer at the same time, the ease and recognizability of the position of the lower layer can be simultaneously controlled.

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, preferably 75% or less. ΔE* _ab is 20 or more, preferably 30 or more, 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, more 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 side of the carrier film, and its position can be accurately grasped. Thereby, the patterned conductive adhesive layer 111 can be accurately aligned and can be temporarily fixed to the printed wiring board 200.

In addition, by making the total light transmittance and ΔE* _ab become predetermined values, the recognizability of the carrier film 112 is also improved, and it is also difficult 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 conductive adhesive layer 111 on the lower side is preferably 40 or more, more preferably 50 or more, 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.

Furthermore, 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 method shown in the examples.

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

紫等。 Specific examples of organic pigments include insoluble azo pigments such as toluidine red, toluidine purple, Hansa yellow, benzidine yellow, and pyrazolinone red; Lithol red, Helio Bordeaux, scarlet Pigment scarlet and permanent red 2B (permanent red) and other soluble azo pigments; derivatives from vat dyes such as alizarin, indanthrene and thioisidi red maroon; phthalocyanine series such as phthalocyanine blue and phthalocyanine green Organic pigments; quinacridone organic pigments such as quinacridone red and quinacridone magenta; perylene organic pigments such as perylene red and perylene scarlet; isoindolinone yellow and isoindolinone orange Dololine-based organic pigments; Pyranthrone-based organic pigments such as Pyranthrone Red and Pyranthrone Orange; Thioindigo-based organic pigments; Condensed azo-based organic pigments; Benzimidazolone-based organic Pigments; Quinophthalone Yellow (Quinophthalone Yellow) and other quinoline-based organic pigments, isoindoline yellow and other isoindoline-based organic pigments; and other pigments include Flavanthrone Yellow, amide yellow, nickel couple Nitrogen Yellow, Copper Amino Yellow, Peripone Orange, Anthrone Orange, Dianthraquinone Red and Two

Purple etc.

In addition, specific examples of inorganic pigments include: silica, alumina, titanium oxide, barium sulfate, calcium carbonate, zinc oxide, sulfuric acid Lead, yellow lead, zinc yellow, carmine (red iron oxide (III)), cadmium red, ultramarine blue, Prussian blue, chromium oxide green, cobalt green, amber, titanium black and synthetic iron black, etc.

Regarding the dye, various compounds previously known 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 coating a silicon-based or non-silicon-based release agent on the surface of the conductive adhesive layer 111 of the carrier film 112. When the release agent layer is formed, its thickness can be about several μm to several tens of μm.

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

When the conductive adhesive layer 111 contains a thermoplastic resin, for the thermoplastic resin, for example, styrene resin, vinyl acetate resin, polyester resin, polyethylene resin, polypropylene resin, imine resin, and Acrylic resin etc. One kind of these resins may be used alone, or two or more kinds may be used in combination.

When the conductive adhesive layer 111 contains a thermosetting resin, for the thermosetting resin, for example, phenol resin, epoxy resin, urethane resin, melamine resin, polyamide resin, and alcohol can be used. Acid resin 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 the molecule can be used. One kind of these compositions may be used alone, or two or more kinds may be used in combination.

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, an amino group, or a hydroxyl group. 2nd The functional group may be selected according to 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 amino group, or the like. Specifically, for example, when the first resin component is epoxy resin, the second resin component can be used: epoxy modified polyester resin, epoxy modified polyamide resin, epoxy modified acrylic Resin, epoxy modified polyurethane polyurea resin, carboxy modified polyester resin, carboxy modified polyamide resin, carboxy modified acrylic resin, carboxy modified polyurethane polyurea resin And urethane modified polyester resin, etc. Among these, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified polyurethane polyurea resin, and urethane modified polyester resin are preferred. Also, when the first resin component is a hydroxyl group, it can be used as the second resin component: epoxy modified polyester resin, epoxy modified polyamide resin, epoxy modified acrylic resin, epoxy modified Polyurethane polyurea resin, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified acrylic resin, carboxyl modified polyurethane polyurea resin and urethane modified Quality polyester resin, etc. Among these, carboxyl modified polyester resin, carboxyl modified polyamide resin, carboxyl modified polyurethane polyurea resin, and urethane modified polyester resin are preferred.

The thermosetting resin may also contain a hardener to promote the thermosetting reaction. When the thermosetting resin has a first functional group and a second functional group, the curing agent can be appropriately selected according to 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 curing agent, a phenol-based curing agent, a cationic curing agent, etc. can be used as the curing agent. One of these may be used alone, or two or more of them may be used in combination. In addition, it can also contain Defoamers, antioxidants, viscosity modifiers, diluents, anti-settling agents, leveling agents, coupling agents, coloring agents, and flame retardants are optional components.

The conductive filler is not particularly limited. For example, metal fillers, metal-coated resin fillers, carbon fillers, and mixtures thereof can be used. As for the metal filler, copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder can be cited. These metal powders can be produced by electrolysis, atomization or reduction. Among them, it is preferably any one of silver powder, silver-coated copper powder and copper powder.

From the viewpoint that the fillers are in contact with each other, the average particle size 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 it may be formed into a spherical shape, a flake shape, a dendritic shape, a fiber shape, or the like.

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% by mass or more, more preferably 10% by mass or more, preferably 95% by mass or less, 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. In addition, when realizing anisotropic conductivity, it is preferably 40% by mass or less, and more preferably 35% by mass or less.

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

From the viewpoint of controlling the filling property, the thickness of the conductive adhesive layer 111 is preferably 1 μm-50 μm.

Furthermore, if necessary, a peelable protective film may be attached to the surface of the conductive adhesive layer 111. 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 may be alternately arranged for winding.

The conductive adhesive film 100 of this embodiment can be temporarily fixed to the printed circuit board 200 after leaving the carrier film 112 and patterning the conductive adhesive layer 111 by half-cutting. 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. At this time, it is not easy to forget to peel off the carrier film 112, which is useful.

The carrier film 112 for the conductive adhesive layer of this embodiment can be used not only as a conductive adhesive film to bond conductive reinforcing plates and heat sinks to flexible printed wiring boards, but also as conductive shielding films. Adhesive layer of carrier film.

[Example]

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

<Production of conductive adhesive film>

Coat a non-silicon release agent on the surface of the predetermined carrier film to form a release agent layer. The thickness of the release agent layer was 0.1 μm. Then, after coating the conductive adhesive layer composition with a wire bar, it was dried at 100° C.×3 minutes to form a conductive adhesive layer with a thickness of 60 μm, and a conductive adhesive film was obtained.

The conductive adhesive layer composition is based on 55 parts by mass of polyurethane polyurea resin having an acid value of 25 mgKOH/g, and the ring is blended It is produced by 45 parts by mass of oxygen resin. In addition, the composition of the epoxy resin is 20 parts by mass of epoxy resin in the form of phenoxy (trade name jER4275, manufactured by Mitsubishi Chemical Co., Ltd.), 20 parts by mass phenol novolac epoxy resin (trade name jER152, manufactured by Mitsubishi Chemical Co., Ltd.), and rubber 5 parts by mass of modified epoxy resin (trade name ERP-4030, manufactured by Asahi Denka). Using a doctor blade (a spatula), it was hard-coated on a release-treated polyethylene terephthalate film, and dried at 100°C for 3 minutes to produce a conductive adhesive film. Furthermore, the squeegee blade is based on the thickness of the conductive adhesive film to be produced, and a product of 1 mil to 5 mil is appropriately selected. Furthermore, 1mil=1/1000 inch=25.4μm. In each example and each comparative example, it was produced so that the thickness of the conductive adhesive film became a predetermined thickness. In addition, the thickness of the conductive adhesive film is measured with a micrometer.

In addition, silver powder (manufactured by Futian Metal Foil Industrial 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 Co., Ltd., SH7000).

<L*'s Evaluation>

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

<Identifiable Evaluation>

Regarding the visibility of the carrier film, when the adhesive film is observed from the carrier film side, the presence of the carrier film can be confirmed visually, it is good (○), and when it cannot be confirmed, it is bad (×).

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 half-cut into a square shape to form a square conductive adhesive layer. Place the semi-perforated adhesive film on the polyimide film with the conductive adhesive layer facing down, and visually confirm whether the square conductive adhesive layer can be seen through from the carrier film side. Specifically, it can be confirmed visually that the square conductive adhesive layer has four corners of 90° as good (○), and it cannot be visually confirmed that the square conductive adhesive layer has four corners of 90° as bad. (×).

(Example 1)

A PET film with a thickness of 50 μm was used as the carrier film. The total light transmittance is 50%, and the L* value of the conductive adhesive layer is 51. In addition, the color difference (ΔE* _ab ) between the PET film and the conductive adhesive layer was 34. The recognizability of the conductive adhesive layer from the carrier film side is good (○), and the recognizability of the carrier film is also good (○).

(Example 2)

A milky white PET film with a thickness of 55 μm was used as the carrier film. The total light transmittance is 65%, and the L* value of the conductive adhesive layer is 69. Also, ΔE* _ab is 34. The recognizability of the conductive adhesive layer from the carrier film side is good (○), and the recognizability of the carrier film is also good (○).

(Example 3)

A milky white PET film with a thickness of 50 μm was used as the carrier film. The total light transmittance was 46%, and the L* value of the conductive adhesive layer was 41. Also, ΔE* _ab is 35. The recognizability of the conductive adhesive layer from the carrier film side is good (○), and the recognizability of the carrier film is also good (○).

(Comparative example 1)

A white PET film with a thickness of 38 μm was used as the carrier film. The total light transmittance was 13%, and the L* value of the conductive adhesive layer was 60. Also, ΔE* _ab is 40. Although the recognizability of the conductive adhesive layer from the carrier film side was poor (×), the recognizability of the carrier film was good (○).

(Comparative example 2)

A white PET film with a thickness of 50 μm was used as the carrier film. The total light transmittance is 5%, and the L* value of the conductive adhesive layer is 55. Also, ΔE* _ab is 32. Although the recognizability of the conductive adhesive layer from the carrier film side was poor (×), the recognizability of the carrier film was good (○).

(Comparative example 3)

A transparent PET film with a thickness of 38 μm was used as the carrier film. The total light transmittance is 90%, and the L* value of the conductive adhesive layer is 53. Furthermore, ΔE* _ab is 2.9. Although the recognizability of the conductive adhesive layer from the carrier film side was good (○), the recognizability of the carrier film was poor (×).

The results of each Example and Comparative Example are summarized in Table 1.

Industrial availability

The carrier film for the conductive adhesive layer of the present invention is not only less likely to be forgotten to peel off the carrier film, but also the layer located on the lower side can be easily identified, and it is useful for various substrate materials having a conductive adhesive layer.

100‧‧‧Conductive adhesive film

111‧‧‧Conductive adhesive layer

112‧‧‧Carrier film

Claims (3)

A carrier film for a conductive adhesive layer is arranged 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 is compatible with the aforementioned 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 carrier film for a conductive adhesive layer as claimed in claim 1 or 2.

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