CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase application filed under 35 U.S.C. § 371 of International Application No. PCT/JP2018/005012, filed Feb. 14, 2018, designating the United States, which claims priority from Japanese Patent Application No. 2017-027983, filed Feb. 17, 2017, and Japanese Patent Application No. 2017-027985, filed Feb. 17, 2017, which are hereby incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to an adhesive film.

BACKGROUND ART

In recent years, various adhesives have been used in the fields of semiconductors, liquid crystal displays, and the like for fixing electronic components, connecting circuits, and the like. In these applications, higher integration density and higher fineness of electronic components, circuits, and the like are progressed, and adhesives are required to have a higher level of performance.

An adhesive having conductive particles dispersed in the adhesive has been used in, for example, connection between a liquid crystal display and a TCP (Tape Carrier Package), connection between an FPC (Flexible Printed Circuit) and a TCP, or connection between an FPC and a printed wiring board. Such an adhesive is required to further enhance the conductivity and reliability.

For example, Patent Literature 1 describes a conductive film comprising a conductive layer containing predetermined silver-coated dendritic copper powder particles on a substrate film, and discloses that such a conductive film can provide sufficient conductive properties without including a silver powder.

CITATION LIST

Patent Literature

Patent Literature 1: International Publication No. WO 2014/021037

SUMMARY OF INVENTION

Technical Problem

The object of the present invention is to provide an adhesive film having excellent reliability.

Solution to Problem

One aspect of the present invention is an adhesive film comprising a first adhesive layer containing a first conductive particle that is a dendritic conductive particle; and a second adhesive layer containing a second conductive particle that is a conductive particle other than the first conductive particle, the second conductive particle having a nonconductive core body and a conductive layer provided on the core body.

The first adhesive layer may further contain the second conductive particle. In this case, the volume proportion of the second conductive particle in the first adhesive layer may be smaller than the volume proportion of the second conductive particle in the second adhesive layer. The first adhesive layer may not contain the second conductive particle.

The adhesive film, in another aspect, comprises the above first adhesive layer, the above second adhesive layer, and a third adhesive layer in this order, and may be an adhesive film with the third adhesive layer containing a third conductive particle that is a dendritic conductive particle.

The third adhesive layer may further contain the second conductive particle. In this case, the volume proportion of the second conductive particle in the third adhesive layer may be smaller than the volume proportion of the second conductive particle in the second adhesive layer. The third adhesive layer may not contain the second conductive particle.

The conductive layer may contain at least one selected from the group consisting of gold, nickel, and palladium.

Advantageous Effects of Invention

The present invention can provide an adhesive film having excellent reliability.

