JP7680305B2 - Resin film laminate, connection structure, and method for producing connection structure - Google Patents

Description

The present invention relates to a resin film laminate, a connection structure, and a method for manufacturing a connection structure.

Conventionally, liquid crystal display devices and organic EL panels have been used as various display means for televisions, PC monitors, smartphones, portable game machines, tablet terminals, wearable terminals, in-vehicle monitors, etc. In recent years, displays with curved surfaces and full-screen displays have been proposed and some have been put to practical use, but these displays use flexible substrates, for example plastic substrates made of resin film laminates with resin films laminated thereon.

In such displays, electronic components such as driving ICs are mounted on a plastic substrate. However, if mounting is performed under the same pressure bonding conditions as mounting on a glass substrate, a high pressure is locally applied from the metal bumps of the IC to the plastic substrate, causing deformation of the plastic substrate. For example, FIG. 6 is a schematic diagram of a connection structure using a conventional plastic substrate. The plastic substrate 1A is formed by bonding a polyimide film 10 on which electrodes and wiring are formed, and a polyester film 12 with an adhesive 13, and an IC 20 having a metal bump 21 is mounted on an electrode (not shown) of the plastic substrate 1A via an anisotropic conductive film 30. When the IC 20 is thermally compressed on the conventional plastic substrate 1A, the plastic substrate 1A is deformed in the area adjacent to the metal bump 21 as shown in FIG. 6, and the gap between the plastic substrate 1A and the IC 20 (the distance between the IC 20 and the polyimide film 10) becomes smaller. In this region, the flow of the anisotropic conductive film 30 causes the conductive particles 31 in the anisotropic conductive film to be unevenly distributed, and the conductive particles 31 unevenly distributed at the ends of the metal bumps 21 tend to cause short circuits. In addition, there is a risk that the wiring on the polyimide film 10 may be broken due to deformation of the plastic substrate 1A.

In response to this, technologies have been proposed to solve the above problems by placing spacers on the anisotropic conductive film or by using an anisotropic conductive film that uses conductive particles with specific physical properties (see, for example, Patent Documents 1 and 2).

JP 2015-185839 A JP 2020-95941 A

The object of the present invention is to provide a resin film laminate, a connection structure, and a method for manufacturing a connection structure that can be used as a plastic substrate and prevent deformation and improve the reliability of connections when electronic components such as ICs are mounted via an anisotropic conductive film by thermocompression bonding.

After extensive research into the above problem, the inventors discovered that the lower the elastic modulus of the adhesive that bonds the polyimide film and polyester film during mounting, the more the resin film base material deforms, the smaller the gap between the plastic substrate and the IC becomes, and problems such as short circuits and disconnections become more likely to occur. They also discovered that the above problem can be solved by using, as the plastic substrate, a resin film laminate material that uses an adhesive that has an elastic modulus equal to or greater than a certain level at the temperature reached during IC mounting, and thus completed the present invention.

That is, the present invention includes the following.
[1] A first resin film having electrodes and wiring formed thereon;
a transparent second resin film;
an adhesive that bonds the first resin film and the second resin film and has an elastic modulus of 100 MPa or more at a temperature reached during mounting of electronic components;
and a resin film laminate having flexibility.
[2] The resin film laminate according to claim 1, wherein the adhesive has an elastic modulus of 100 MPa or more at 165°C.
[3] The resin film laminate according to claim 1 or 2, wherein the adhesive is mainly composed of a thermosetting epoxy resin.
[4] The resin film laminate according to any one of claims 1 to 3, wherein the first resin film is polyimide and the second resin film is polyester.
[5] The resin film laminate according to any one of claims 1 to 4, which is used as a plastic substrate for COP (Chip On Plastic) mounting.
[6] A connection structure in which the resin film laminate according to any one of claims 1 to 5 and an electronic component are connected by an anisotropic conductive film.
[7] A method for producing a connection structure in which the resin film laminate according to any one of claims 1 to 5 and an electronic component are connected by an anisotropic conductive film.

The resin film laminate of the present invention can achieve high connection reliability, even when used on a plastic substrate on which electronic components such as a driving IC are mounted, because it can suppress short circuits and disconnections caused by deformation of the substrate.

FIG. 1 is a cross-sectional view showing an example of a resin film laminate according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the elastic modulus of the adhesive of the resin film laminate material and the gap between the connection structure and the electronic component. FIG. 3 is a cross-sectional view showing an example of a connection structure using a resin film laminate according to an embodiment of the present invention. FIG. 4 is a metallurgical microscope photograph of a connection structure using a resin film laminate according to an embodiment of the present invention. FIG. 5 is a metallurgical microscope photograph of a connection structure using a conventionally used resin film laminate material. FIG. 6 is a schematic diagram of a connection structure using a conventional plastic substrate.

The present invention will be described in detail below with reference to preferred embodiments. The present invention is not limited to the following description, and each component can be modified as appropriate without departing from the spirit of the present invention.

[Resin film laminate]
1 is a cross-sectional view showing an example of a resin film laminate according to an embodiment of the present invention. The resin film laminate 1 includes a first resin film 10 on which electrodes 11 and wiring 11a are formed, a transparent second resin film 12, and an adhesive 13 that bonds the first resin film 10 and the second resin film 12 and has an elastic modulus of 100 MPa or more at a temperature reached during mounting of electronic components. The resin film laminate 1 of the present invention is flexible and can be suitably used as a plastic substrate for mounting COPs.

The first resin film 10 has electrodes 11 and wiring 11a formed on one surface. The electrodes 11 and wiring 11a are formed on the first resin film 10 by patterning, and are made of metal wiring such as titanium/aluminum/titanium. The first resin film 10 is not limited as long as it is flexible, but is preferably made of polyimide, which has excellent heat resistance. The thickness of the first resin film 10 is preferably about 10 μm to 50 μm from the standpoint of flexibility, heat resistance, etc.

The second resin film 12 is not limited as long as it is a flexible and transparent resin, but is preferably polyester from the viewpoints of transparency, durability, cost, etc. By selecting a transparent film as the second resin film 12, the alignment mark can be recognized from the second resin film side, and the electronic component to be mounted and the resin film laminate material 1 can be connected with high accuracy. From the viewpoints of durability, flexibility, etc., the thickness of the second resin film 12 is preferably about 20 μm to 100 μm.

The adhesive 13 bonds the first resin film 10 and the second resin film 12. The adhesive 13 has an elastic modulus of 100 MPa or more at a temperature reached when mounting an electronic component. The mounting temperature is the temperature (the temperature reached by the anisotropic conductive film) when mounting an electronic component on the resin film laminate 1 in a connection structure described below. The temperature reached by the adhesive 13 when mounting an electronic component is the temperature reached by the adhesive 13 when heat during mounting is transmitted through the first resin film 10.
The mounting temperature that the adhesive 13 reaches when mounting electronic components can be changed depending on the materials and thicknesses used for the first resin film 10, the second resin film 12, and the anisotropic conductive film described below, but for example, the temperature that the adhesive 13 reaches is 165° C. The adhesive 13 needs to have an elastic modulus of 100 MPa or more at 165° C. By having an elastic modulus of 100 MPa or more at the temperature that is reached when mounting electronic components, deformation of the resin film laminate material 1 can be suppressed, and a decrease in the gap between the electronic components and the resin film laminate material 1 can be prevented.

Fig. 2 is a diagram showing the relationship between the elastic modulus of the adhesive 13 and the gap between the resin film laminate 1 and the electronic component in a connection structure (see Fig. 3) in which an electronic component (IC, etc.) is mounted on the resin film laminate 1 using an anisotropic conductive film. Fig. 2 shows an interpolation of the results of a simulation of the gap between the resin film laminate 1 and the electronic component when the elastic modulus of the adhesive 13 is changed in a connection structure under the following conditions.
(Resin film laminate)
First resin film: Polyimide assumed (thickness 25 μm, elastic modulus 5.8 GPa)
Second resin film: Polyester assumed (thickness 75 μm, elastic modulus 4.5 GPa)
Adhesive: Thickness 15 μm
(Anisotropic Conductive Film)
Binder resin: Thermosetting epoxy resin (thickness 10 μm, uncured state)
(Electronic Components)
Substrate material: Silicon wafer (elastic modulus 130 GPa)
Metal bump: Gold (elastic modulus 78 GPa)
(Implementation conditions)
The resin film laminate 1, the anisotropic conductive film, and the electronic components were placed on a stage maintained at 30°C, and thermocompression bonded with a heat tool at 273°C, 30 MPa, and 5 seconds via a 100 μm thick buffer material (Teflon (registered trademark), elastic modulus 0.55 GPa). The thermocompression bonding conditions were such that the anisotropic conductive film reached a hardening temperature (210°C), and the temperature of the adhesive 13 reached during thermocompression bonding was 165°C.

According to the simulation data shown in FIG. 2, if the elastic modulus of the adhesive 13 at the temperature reached when the electronic component of the connection structure is mounted, that is, the elastic modulus at 165°C, is 100 MPa or more, the gap between the resin film laminate 1 and the electronic component will be 6 μm or more. In actual evaluation, when the gap is below 6 μm, the deformation of the resin film laminate 1 becomes large, resulting in concerns about the connection reliability (Comparative Example 2 described later). From the above, in the resin film laminate of the present invention, it is necessary that the elastic modulus of the adhesive at 165°C is 100 MPa or more. Note that even if the heating temperature in the heat tool is the same, the temperature reached by the adhesive may change depending on the thickness of the first resin film 10 and the second resin film 20, etc., but if the elastic modulus is 100 MPa or more under the temperature conditions during mounting, the gap between the resin film laminate 1 and the electronic component can be maintained within an appropriate range.

The adhesive 13 is not particularly limited as long as it has an elastic modulus of 100 MPa or more at the temperature reached when mounting electronic components, but a thermosetting epoxy resin is preferred. Examples of thermosetting epoxy resins that can be used include PHENOXY RESIN PKHH and EPICLON HP4032D. Additionally, anionic and cationic curing agents can be used as latent curing agents for thermosetting epoxy resins.

The resin film laminate 1 can suppress deformation of the resin film laminate 1 when mounting electronic components by using an adhesive 13 with an elastic modulus of 100 MPa or more at the temperature reached during mounting, but in order to prevent a decrease in the gap between the electronic components and the resin film laminate 1, dummy bumps may be provided on the surface of the first resin film 10 on which the electrodes 11 and wiring 11a are formed. The dummy bumps are preferably formed of an insulating material such as resin in a shape and size that does not impede the flow of the anisotropic conductive film 30 in areas where the electrodes 11 and wiring 11a are not formed.

[Connection structure]
3 is a cross-sectional view showing an example of a connection structure using the resin film laminate according to the embodiment of the present invention. The connection structure 100 is formed by connecting the above-described resin film laminate 1 and an electronic component 20 with an anisotropic conductive film 30.

(Anisotropic Conductive Film)
The anisotropic conductive film 30 contains conductive particles 31 in a binder resin 32. The anisotropic conductive film 30 electrically connects the metal bumps 21 of the electronic component 20 and the electrodes 11 of the resin film laminate 1 via the conductive particles 31. The anisotropic conductive film 30 is a thermosetting or photocuring adhesive such as ultraviolet light, and is attached onto the resin film laminate 1. After the electronic component 20 is placed on the anisotropic conductive film 30, the anisotropic conductive film 30 is fluidized by being heated and pressed by a thermocompression head or the like, so that the conductive particles 31 are crushed between the metal bumps 21 and the electrodes 11, thereby conducting the metal bumps 21 and the electrodes 11. The anisotropic conductive film 30 is then cured by heating or light irradiation.

The binder resin 32 consists of a film-forming resin, a thermosetting resin, a latent curing agent, a silane coupling agent, etc.

The film-forming resin contained in the binder resin 32 is preferably a resin with a weight average molecular weight of about 10,000 to 80,000. Examples of film-forming resins include epoxy resins, modified epoxy resins, urethane resins, and phenoxy resins.

Examples of thermosetting resins contained in the binder resin 32 include epoxy resin and acrylic resin.

Examples of epoxy resins include naphthalene type epoxy resins, biphenyl type epoxy resins, phenol novolac type epoxy resins, bisphenol type epoxy resins, stilbene type epoxy resins, triphenolmethane type epoxy resins, phenol aralkyl type epoxy resins, naphthol type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, etc.

Examples of acrylic resins include methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, epoxy acrylate, ethylene glycol acrylate, diethylene glycol acrylate, trimethylolpropane triacrylate, dimethyloltricyclodecane diacrylate, tetramethylene glycol tetraacrylate, 2-hydroxy-1,3-diacryloxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxyethoxy)phenyl]propane, dicyclopentenyl acrylate, dicyclodecanyl acrylate, tris(acryloxyethyl)isocyanurate, urethane acrylate, and epoxy acrylate.

Examples of latent curing agents contained in the binder resin 32 include heat-curing and UV-curing agents. The latent curing agent is activated and starts a reaction by various triggers such as heat, light, and pressure depending on the application. The thermally activated latent curing agent can be activated by a method of generating active species (cations, anions, radicals) by a dissociation reaction caused by heating, a method of dissolving in the epoxy resin at a temperature above a certain level and starting a curing reaction, or a method of encapsulating in a molecular sieve or microcapsule and dissolving at a certain temperature to start a curing reaction. Examples of thermally activated latent curing agents include imidazoles, hydrazides, boron trifluoride-amine complexes, sulfonium salts, amine imides, polyamine salts, and dicyandiamide.

Examples of silane coupling agents contained in the binder resin 32 include various silane coupling agents such as epoxy-based, amino-based, mercapto-based, sulfide-based, and ureido-based silane coupling agents.

The conductive particles 31 contained in the binder resin 32 may be known conductive particles used in anisotropic conductive films. Examples of conductive particles include particles of metals such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, and gold; particles of alloys of these metals; and coated particles in which metal is coated on the surface of particles such as metal oxides, carbon, graphite, glass, ceramics, and resins. When using metal-coated resin particles in which a metal is coated on the surface of resin particles, examples of the material for the resin particles include epoxy resin, phenolic resin, acrylic resin, acrylonitrile-styrene (AS) resin, benzoguanamine resin, divinylbenzene resin, and styrene resin. Note that the conductive particles may be insulated by further coating the surface of the particles with an insulating thin film or attaching insulating particles to the surface in order to avoid the risk of short circuits between terminals, as long as the conductive particles do not interfere with the conductive performance after connection.

[Method of manufacturing the connection structure]
The method for producing the connection structure of the present invention is not particularly limited as long as it is possible to produce a connection structure 100 in which an electronic component 20 is connected to the resin film laminate 1 of the present invention via an anisotropic conductive film 30. An example of a method for producing the connection structure 100 of the present invention is shown below.

The manufacturing method of the connection structure 100 of the present invention includes a step of crimping an electronic component 20 to the resin film laminate material 1 of the present invention with an anisotropic conductive film 30 interposed therebetween.

First, the resin film laminate 1 of the present invention is placed on a stage, an anisotropic conductive film 30 is provided thereon, and then an electronic component 20 is placed thereon. After the anisotropic conductive film 30 is provided on the resin film laminate 1 placed on the stage, the electrodes 11 of the resin film laminate 1 and the metal bumps 21 of the electronic component 20 are aligned so as to face each other, and temporary pressure bonding is performed from the electronic component 20 side using a heat tool. The temperature, pressure, and time during temporary pressure bonding may be appropriately determined according to the specific design, and may be, for example, 60 to 80°C, 0.5 to 2 MPa, and 0.5 to 2 seconds. By performing such temporary pressure bonding prior to performing the main pressure bonding described later, the resin film laminate 1 and the electronic component 20 can be more accurately aligned and connected, which is preferable. By performing temporary pressure bonding, it is expected that positional deviation during main pressure bonding, which is pressed with a higher pressure, can be suppressed.

After the temporary bonding, the final bonding is performed from the electronic component 20 side using a heat tool. The temperature, pressure, and time during the final bonding may be any known condition used when bonding electronic components using an adhesive film, and may be appropriately determined according to the specific design. For example, the final bonding is performed at 210°C (the temperature of the anisotropic conductive film), 30 MPa, and 5 seconds.

Regardless of whether temporary or permanent bonding is performed, a cushioning material (e.g., a cushioning sheet) may be provided between the electronic component 20 and the heat tool. The type of cushioning material, including whether or not it is used, may be adjusted and determined appropriately depending on the combination of electronic components.

The resin film laminate 1 of the present invention is used as a plastic substrate for COP mounting, and even when an electronic component 20 is mounted under mounting conditions similar to those for a glass substrate, it does not deform, so the gap between the resin film laminate 1 and the electronic component 20 can be maintained, and short circuits, breaks, etc. can be effectively prevented.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[Anisotropic Conductive Film]
The anisotropic conductive film was prepared by adding 25 parts by mass of phenoxy resin (PHENOXY RESIN PKHH, manufactured by Tomoe Chemical Industry Co., Ltd.), 10 parts by mass of epoxy resin (EPICLON HP-4032D, manufactured by DIC Corporation), 33 parts by mass of latent hardener (NOVACURE (registered trademark) HX-3941HP, manufactured by Asahi Kasei Corporation), 2 parts by mass of silane coupling agent (SILQUEST A-187 SILANE, manufactured by Momentive Performance Materials Japan LLC), and 30 parts by mass of conductive particles (Micropearl, manufactured by Sekisui Chemical Co., Ltd., Ni resin particles having an average particle size of 3 μm) to a solvent to prepare a binder resin composition, which was then applied to a release film and dried.

[Electronic Components]
The electronic component used for evaluation was an IC with two rows of metal bumps arranged along one side edge and one row along the other side edge. The metal bumps were gold bumps with a width of 10 μm, a pitch of 8 μm between adjacent bumps, and a height of 9 μm.

[Example 1]
A polyimide film (Kapton 100EN, manufactured by DuPont-Toray Co., Ltd., thickness 25 μm) was used as the first resin film, and a polyester film (Toyobo Polyester Film E5000, manufactured by Toyobo Co., Ltd., thickness 75 μm) was used as the second resin film. As an adhesive, 25 parts by mass of phenoxy resin (PHENOXY RESIN PKHH, manufactured by Tomoe Chemical Industry Co., Ltd.), 10 parts by mass of epoxy resin (EPICLON HP-4032D, manufactured by DIC Corporation), 33 parts by mass of latent curing agent (NOVACURE (registered trademark) HX-3941HP, manufactured by Asahi Kasei Corporation), and 2 parts by mass of silane coupling agent (SILQUEST A-187 SILANE, manufactured by Momentive Performance Materials Japan LLC) were added to a solvent to prepare an adhesive composition, which was then applied to a second resin film to a thickness of 15 μm. After drying, the first resin film was laminated thereon, and pressed at 170 ° C., 3 MPa, and 70 minutes using a vacuum single plate press to obtain a resin film laminate. The electrodes on the first resin film had a width of 10 μm, a pitch between adjacent electrodes of 8 μm, and were made of Ti 50 nm/Al 600 nm/Ti 50 nm.

An electronic component was mounted on the prepared resin film laminate via an anisotropic conductive film. The mounting was performed using a 100 μm thick buffer material (Teflon (registered trademark)) and was thermocompressed with a heat tool at 273°C, 30 MPa, and 5 seconds. The temperature of the anisotropic conductive film was heated to 210°C and the temperature of the adhesive was heated to 165°C by this thermocompression. The mounting was performed by shifting the minimum conductor spacing between the metal bumps of the electronic component and the electrodes of the resin film laminate to 4 μm, and the occurrence of short circuits and disconnections was confirmed at 24,000 connection points. The occurrence of short circuits and disconnections was evaluated as A for no occurrence, B for 1 to 9 occurrences, and C for 10 or more occurrences. The gap between the electronic component and the resin film laminate was measured at a point about 0.6 mm inward from the end of the input bump arranged on the side edge of the electronic component. The elastic modulus at the temperature reached by the adhesive during mounting was measured using DMA (manufactured by Seiko Instruments Inc.). The results are shown in Table 1.
Furthermore, a metallurgical microscope photograph of the obtained connection structure is shown in Fig. 5. Fig. 5 shows the connection structure photographed from the second resin film side. In the figure, many small dots, not marked with symbols, are conductive particles.

[Example 2]
As an adhesive, 25 parts by mass of phenoxy resin (PHENOXY RESIN PKHH, manufactured by Tomoe Chemical Industry Co., Ltd.), 20 parts by mass of epoxy resin (JER YL980, manufactured by Mitsubishi Chemical Co., Ltd.), 10 parts by mass of epoxy resin (EPICLON HP-4032D, manufactured by DIC Corporation), 13 parts by mass of latent curing agent (SAN-AID SI-60L, manufactured by Sanshin Chemical Industry Co., Ltd.), 2 parts by mass of silane coupling agent (SILQUEST A-187 SILANE, manufactured by Momentive Performance Materials Japan LLC) were added to the solvent to prepare an adhesive composition, except that a resin film laminate was produced in the same manner as in Example 1 to obtain a connection structure. The obtained resin film laminate and connection structure were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
As an adhesive, phenoxy resin (PHENOXY RESIN PKHH, manufactured by Tomoe Chemical Industry Co., Ltd.) 12.5 parts by mass, epoxy resin (Epotohto YD020H, manufactured by Nippon Steel Chemical & Material Co., Ltd.) 12.5 parts by mass, epoxy resin (EPICLON HP-4032D, manufactured by DIC Corporation) 10 parts by mass, latent curing agent (Novacure (registered trademark) HX-3941HP, manufactured by Asahi Kasei Corporation) 33 parts by mass, silane coupling agent (SILQUEST A-187 SILANE, manufactured by Momentive Performance Materials Japan LLC) 2 parts by mass were added to the solvent to prepare an adhesive composition, except that a resin film laminate was produced in the same manner as in Example 1 to obtain a connection structure. The obtained resin film laminate and connection structure were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
A resin film laminate was produced and a connection structure was obtained in the same manner as in Example 1, except that an adhesive composition was prepared by mixing 60 parts by mass of 2-ethylhexyl acrylate, 34 parts by mass of butyl acrylate, 5 parts by mass of acrylic acid, and 1 part by mass of 2-hydroxyethyl methacrylate as the adhesive. The obtained resin film laminate and connection structure were evaluated in the same manner as in Example 1. The results are shown in Table 1.
Furthermore, a metallurgical microscope photograph of the obtained connection structure is shown in Fig. 6. Fig. 6 shows the connection structure photographed from the second resin film side. In the figure, many small dots, not marked with symbols, are conductive particles.

From the results in Table 1, it was confirmed that in the connection structures of Examples 1 and 2, which used an adhesive with an elastic modulus of 100 MPa or more at the temperature reached during mounting, the gap between the electronic component and the resin film laminate was 6 μm or more, making it possible to prevent the occurrence of short circuits and breaks.
In addition, in the metallurgical microscope photograph of FIG. 5, the conductive particles in the anisotropic conductive film are uniformly present in the connection structure of Example 1, but in the metallurgical microscope photograph of FIG. 6, it was confirmed that the anisotropic conductive film flows and the conductive particles are localized in the connection structure of Comparative Example 2 because the resin film laminate material deforms near the metal bump. From FIGS. 5 and 6, it can be seen that in Example 1, which uses an adhesive with an elastic modulus of 100 MPa or more at the temperature reached when mounting electronic components, the localization of the conductive particles can be suppressed, that is, short circuits can be prevented. Although not shown, it was also confirmed that the conductive particles are uniformly present in the anisotropic conductive film in the connection structure of Example 2.

REFERENCE SIGNS LIST 1 resin film laminate, 10 first resin film, 11 electrode, 11a wiring, 12 second resin film, 13 adhesive, 20 electronic component, 21 metal bump, 30 anisotropic conductive film, 31 conductive particles, 32 binder resin, 100 connection structure

Claims (5)

a first resin film on which electrodes and wiring are formed;
a transparent second resin film;
and an adhesive that bonds the first resin film and the second resin film, the adhesive being mainly made of a thermosetting epoxy resin and having an elastic modulus of 100 MPa or more at 165°C, which is a temperature reached when mounting electronic components. 2. The resin film laminate according to claim 1 , wherein the first resin film is made of polyimide and the second resin film is made of polyester. 3. The resin film laminate according to claim 1, which is used as a plastic substrate for COP (Chip On Plastic) mounting. A connection structure in which the resin film laminate according to any one of claims 1 to 3 and an electronic component are connected by an anisotropic conductive film. A method for producing a connection structure, comprising connecting the resin film laminate according to any one of claims 1 to 3 and an electronic component via an anisotropic conductive film.

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