CN114686125A

CN114686125A - Circuit connection bonding adhesive film

Info

Publication number: CN114686125A
Application number: CN202210473838.7A
Authority: CN
Inventors: 李德
Original assignee: Changzhou Dechuang High Tech Material Technology Co ltd
Current assignee: Changzhou Dechuang High Tech Material Technology Co ltd
Priority date: 2022-04-29
Filing date: 2022-04-29
Publication date: 2022-07-01

Abstract

The invention provides a circuit connection adhesive film, and relates to the technical field of electrical elements; the circuit connection adhesive film comprises a first adhesive layer and a second adhesive layer which are stacked; the first bonding layer is used for being connected with the glass substrate; the first adhesive layer comprises a first adhesive layer and conductive particles dispersed in the first adhesive layer; the second bonding layer is used for connecting the polyimide substrate; the second adhesive layer comprises a second adhesive layer; the linear expansion coefficient of the first adhesive layer is smaller than that of the second adhesive layer. According to the circuit connection adhesive film provided by the invention, the two adhesive layers with different linear expansion coefficients are arranged, so that the internal stress caused by different thermal expansion amounts of the polyimide substrate and the glass substrate in the reliability test process can be reduced, the bonding interface between the circuit connection adhesive film and the substrate is prevented from being peeled, the increase of the connection resistance is further avoided, and the connection strength of the circuit connection adhesive film is improved.

Description

Circuit connection bonding adhesive film

Technical Field

The invention relates to the technical field of electrical elements, in particular to a circuit connection bonding adhesive film.

Background

Conventionally, for a circuit board having opposing electrodes, an adhesive film in which conductive particles are dispersed is generally provided between the two electrodes as a circuit connection adhesive film; for example, an adhesive film having an anisotropic conductive function, which is obtained by dispersing conductive particles in an epoxy adhesive or an acrylic adhesive, is a typical circuit connection adhesive film.

The adhesive film having an anisotropic conductive function is widely used for electrical connection between a LCD glass substrate and a tcp (tape Carrier package) or cof (chip On flex) On which a semiconductor for driving a liquid crystal display is mounted.

After a polyimide substrate (generally called TCP, COF, or FPC) is attached to an LCD glass substrate by the adhesive film having an anisotropic conductive function, it is usually necessary to perform a plurality of tests by exposing the product to various environments in order to confirm the reliability of the attachment.

In the bonding process, internal stress occurs in a workpiece due to different linear expansion coefficients of the glass substrate and the polyimide substrate; in the test process, particularly in a high temperature and high humidity test (exposure for 500 h-1000 h under 85 ℃/85% environment) and a thermal shock test (repeated test for 500-1000 cycles under high temperature of 100 ℃ to low temperature of-40 ℃), peeling is easy to occur at the bonding interface of one substrate side or two substrates, so that the connection resistance is increased.

As a conventional technique, there is a technique of dispersing rubber particles in an adhesive in order to reduce internal stress caused by a difference in thermal expansion coefficient after bonding. Although the effect of interfacial peeling was exhibited for polyimide substrates, no significant improvement was observed for interfacial peeling in which the interface was a glass substrate.

In recent years, as LCD modules have been made finer and finer, COF pitches have become narrower, and a Short (Short) problem has arisen between adjacent electrodes due to a difference in linear expansion between a glass substrate and a COF substrate during connection. As a countermeasure, a laminated structure of an anisotropic conductive adhesive layer in which conductive particles are dispersed and an insulating adhesive layer not containing conductive particles is adopted, and the thickness of the anisotropic conductive adhesive layer is 25.0 to 77.5% of the average particle diameter of the conductive particles, so that the capturing efficiency of the conductive particles on the electrode is remarkably improved and the connection reliability is also excellent as compared with the conventional circuit connection adhesive film. However, although the polyimide interface of COF reduces the risk of short circuit, the increase in connection resistance is not technically improved because peeling occurs at the LCD glass interface.

There is a technique for forming a circuit connection adhesive film having an insulating property between adjacent circuit electrodes and a conductive property between opposing circuit electrodes and having a good film-forming property (see japanese patent invention No. 2016-. The high-concentration silicon dioxide filler and the organic filler are filled, and the content of the silicon dioxide filler is more than 10% and less than 80% in mass fraction or more than 5% and less than 40% in volume fraction. Meanwhile, the organic filler is required to be 5 to 20% by mass or 5 to 20% by volume. When the silica filler is filled in an amount of 10% by mass or more, there is no problem if the connecting material is in the form of paste, but when the connecting material is in the form of a glue film, the viscosity of the adhesive is significantly improved, and the adhesive between the opposing terminals cannot be eliminated in a fine pitch substrate of 50 μm or less, which may cause poor connection.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: in order to solve the problem that the circuit connection bonding adhesive film in the prior art is easy to peel off from the bonding interface of a substrate to increase the connection resistance, the invention provides the circuit connection bonding adhesive film.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a circuit connection adhesive film comprises a first adhesive layer and a second adhesive layer which are arranged in a stacked mode; wherein the content of the first and second substances,

the first bonding layer is used for being connected with the glass substrate; the first adhesive layer comprises a first adhesive layer and conductive particles dispersed in the first adhesive layer;

the second bonding layer is used for connecting the polyimide substrate; the second adhesive layer comprises a second adhesive layer;

the linear expansion coefficient of the first adhesive layer is smaller than that of the second adhesive layer.

Optionally, the thickness of the first adhesive layer is 1 to 2 times the particle size of the conductive particles.

Optionally, the first adhesive layer further comprises inorganic nanoparticles dispersed in the first adhesive layer.

Optionally, the mass fraction of the inorganic nanoparticles in the first adhesive layer is in a range from 2% to 15%.

Optionally, the inorganic nanoparticles comprise inorganic silica particles.

Optionally, the surface of the inorganic silica particles is hydrophobically treated with at least one of dimethylsiloxane, trimethylsilyl, and octylsilane.

Optionally, the second adhesive layer further includes a core-shell type organic powder dispersed in the second adhesive layer.

Optionally, the mass fraction of the core-shell organic powder in the second adhesive layer ranges from 5% to 20%.

Optionally, the core-shell organic powder comprises a core layer and a shell layer coated outside the core layer; the core layer is at least one of (methyl) acrylic polymer and butadiene polymer; the shell layer is a methyl methacrylate monomer or a copolymer thereof.

Optionally, the core layer is selected from at least one of poly (meth) acrylate rubber, polybutylene rubber, polyisoprene rubber, styrene butadiene rubber.

The invention has the beneficial effects that: according to the circuit connection adhesive film provided by the invention, through the structure of two adhesive layers with different linear expansion coefficients, when a glass substrate and a polyimide substrate are connected, the second adhesive layer with a larger linear expansion coefficient is connected with the polyimide substrate with a larger thermal expansion coefficient, and the first adhesive layer with a smaller linear expansion coefficient is connected with the glass substrate with a smaller thermal expansion coefficient, so that the internal stress caused by different thermal expansion amounts of the polyimide substrate and the glass substrate in the test process can be reduced, the peeling of the bonding interface of the circuit connection adhesive film and the glass substrate or the polyimide substrate is avoided, the increase of the connection resistance is avoided, and the connection strength of the circuit connection adhesive film is improved.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic view of the structure of the adhesive film for circuit connection according to the present invention;

FIG. 2 is a schematic view showing the assembly of the adhesive film for circuit connection of the present invention with a glass substrate and a polyimide substrate.

Detailed Description

The present invention will now be described in further detail. The embodiments described below are exemplary and are intended to be illustrative of the present invention and should not be construed as limiting the present invention, and all other embodiments that can be obtained by one of ordinary skill in the art based on the embodiments of the present invention without inventive step fall within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "first" and "second" are used merely for simplifying the description, and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

As the LCD module gradually tends to be highly refined and lightweight, the corresponding glass substrate and polyimide substrate are gradually thinned, and the distance between the two is gradually refined; in order to reduce the number of components, the widths of the glass substrate and the polyimide substrate are generally increased so as to mount a larger number of components; as the widths of the glass substrate and the polyimide substrate increase, the problem caused by the difference in thermal expansion becomes more significant.

In order to solve the problem that the circuit connection adhesive film in the prior art is easy to peel off from the bonding interface of the substrate to increase the connection resistance, the invention provides the circuit connection adhesive film, which comprises a first bonding layer and a second bonding layer which are arranged in a stacked manner, as shown in figure 1; the first bonding layer is used for being connected with the glass substrate; the first adhesive layer includes a first adhesive layer, and conductive particles dispersed in the first adhesive layer so as to achieve electrical connection in a pressing direction; the second bonding layer is used for connecting the polyimide substrate; the second adhesive layer comprises a second adhesive layer; in the present invention, it is preferable that both the first adhesive layer and the second adhesive layer are an epoxy adhesive layer or an acrylic adhesive layer; the specific materials of the first adhesive layer and the second adhesive layer can be the same or different; in order to reduce the internal stress of a product obtained by connecting the glass substrate and the polyimide substrate through the circuit connection adhesive film, the linear expansion coefficient of the first adhesive layer is preferably smaller than that of the second adhesive layer.

It should be noted that, in order to describe the structure of the circuit connection adhesive film, the circuit connection adhesive film is divided into a first adhesive layer and a second adhesive layer; however, in the actual use process, the first adhesive layer and the second adhesive layer are of an integral structure which is mutually adhered, namely, the circuit connection adhesive film provided by the invention has no delamination phenomenon in the use process.

According to the circuit connection adhesive film provided by the invention, by setting the structure of two adhesive layers with different linear expansion coefficients, when a glass substrate and a polyimide substrate are connected, the second adhesive layer with a larger linear expansion coefficient is connected with the polyimide substrate with a larger thermal expansion coefficient, and the first adhesive layer with a smaller linear expansion coefficient is connected with the glass substrate with a smaller thermal expansion coefficient, so that the internal stress caused by different thermal expansion amounts of the polyimide substrate and the glass substrate in the test process can be reduced, the deformation is reduced, the peeling of the adhesive interface of the circuit connection adhesive film and the glass substrate or the polyimide substrate is avoided, and the circuit connection adhesive film can also keep good connection reliability even after the test is carried out in a harsh environment, and further the increase of the connection resistance is avoided; meanwhile, the connection strength of the circuit connection adhesive film can be improved through the conductive particles dispersed in the first adhesive layer.

The conductive particles may be conductive metal particles such as Au, Ag, Cu, Ni, or conductive particles obtained by coating a conductive metal on the outside of particles such as nonconductive glass, ceramics, plastics, or the like; the particle diameter of the conductive particles may be determined according to the wiring pitch of the polyimide substrate and the height of the electrodes; when the particle diameter of the conductive particles having resin particles as cores is less than 2 μm, it is difficult to exhibit the elasticity and recovery function of the core material; if the particle size of the conductive particles is larger than 20 μm, the distance between the two substrates is not easy to be refined; accordingly, the particle size of the conductive particles of the present invention and the preferred range is 2 to 20 μm.

The conductive particles are preferably dispersed in the surface layer side in a direction biased toward the thicker layer of the adhesive film. In order to ensure the connection strength between the metal electrode of the polyimide substrate and the glass substrate and improve the capture efficiency of the conductive particles on the electrode, as shown in fig. 1, the thickness of the first adhesive layer is preferably 1 to 2 times the particle size of the conductive particles, so that a sufficient low linear expansion adhesive layer can be maintained between the metal electrode of the polyimide substrate and the glass substrate, and high connection reliability can be achieved.

Specifically, D in FIG. 1 is the thickness of the first adhesive layer, F_ORIs a first adhesive layer, F_INA second adhesive layer; wherein the linear expansion coefficient of the first adhesive layer is smaller than that of the second adhesive layer; after the circuit connection adhesive film is connected with the glass substrate and the polyimide substrate, as shown in FIG. 2, P in FIG. 2 isA polyimide substrate, G is a glass substrate; since the glass substrate is connected in a state where the conductive particles are present in the first adhesive layer, peeling is less likely to occur at the interface of the glass substrate; when the thickness of the first adhesive layer is less than 1 time the diameter of the conductive particles, the filling of the low linear expansion adhesive layer between the metal electrode of the polyimide substrate and the glass substrate becomes insufficient, which results in poor connection reliability, and peeling easily occurs at the interface of the glass substrate, which results in an increase in connection resistance; on the other hand, if the thickness of the first adhesive layer is more than 2 times the diameter of the conductive particles, the filling of the high linear expansion adhesive layer to be present on the polyimide interface side becomes insufficient, and stress relaxation by thermal expansion and contraction of polyimide becomes difficult, and connection reliability is affected, and peeling is likely to occur at the interface of the polyimide substrate, which is not preferable; therefore, in the present invention, the thickness of the first adhesive layer is preferably 1 to 2 times the particle diameter of the conductive particles.

Since the wiring portion actually electrically connected is biased toward the glass substrate side as shown in fig. 2, when a layer on the conductive particle side is used by being bonded to the glass substrate, the adhesive layer having a low coefficient of linear expansion fixes the wiring material, and the wiring portion can be electrically connected by the conductive particles. Therefore, the presence of the conductive particles in the adhesive having a low coefficient of linear expansion on the glass substrate side can improve the connection reliability. On the other hand, when an adhesive layer having a high coefficient of expansion of the bonding line is bonded to the polyimide substrate side having a large thermal expansion and contraction, not only is the variation (internal stress) due to the thermal expansion and contraction during bonding alleviated, but also the adhesive strength is greatly improved.

In order to further reduce the linear expansion coefficient of the first adhesive layer, the first adhesive layer preferably further includes inorganic nanoparticles dispersed in the first adhesive layer, so that the linear expansion coefficient of the first adhesive layer is closer to that of glass, stress near a glass interface is relaxed, and connection reliability is improved.

In order to ensure that the specific surface area of the inorganic nanoparticles meets the requirement, the particle size range of the inorganic nanoparticles is preferably 1-500 nm, and further preferably 1-200 nm.

The higher the content of the inorganic nanoparticles is, the lower the linear expansion coefficient of the first bonding layer is, but the bonding strength tends to be reduced; in order to take the linear expansion coefficient and the connection strength of the first bonding layer into consideration, the mass fraction of the inorganic nanoparticles in the first bonding layer is preferably in the range of 2-15%.

The inorganic nanoparticles may be nano TiO₂And may be inorganic silica particles; preferably, the inorganic nanoparticles are inorganic silica particles.

In order to improve the hydrophobicity of the inorganic silica particles and to improve the reliability of connection after environmental tests, it is preferable in the present invention that the surface of the inorganic silica particles is subjected to a hydrophobic treatment with at least one of dimethylsiloxane, trimethylsilyl and octylsilane.

The inorganic silica particles in which the hydrophobic surface treatment is carried out may be prepared according to the prior art or may be purchased directly, for example, inorganic silica particles having a primary particle diameter of 14nm, which are manufactured by EVONIC corporation under the product name of aerosil r202, and which are treated with dimethylsilicone; inorganic silica particles having a primary particle diameter of 12nm, which were prepared by the company EVONIC and were treated with an octanesilane, under the product name AEROSILR 805; inorganic silica particles having a primary particle diameter of 7nm, which were produced by EVONIC and were treated with trimethylsilyl, and the product name was AEROSILR 812.

In the present invention, it is preferable that the inorganic nanoparticles are kneaded and dispersed in the resin by a three-roll grinder (model DS50, manufactured by Longxin Intelligent Equipment Co.).

In order to alleviate the stress during the curing process, the second adhesive layer preferably further comprises core-shell organic powder dispersed in the second adhesive layer; by adding the core-shell type organic powder to the second adhesive layer, it has the effect of relaxing the stress during the curing process without significantly lowering the linear expansion coefficient of the second adhesive layer. By adding a core-shell type organic powder to an adhesive film layer on a polyimide substrate side, the core-shell type organic powder has a higher linear expansion coefficient than glass, so that stress from the polyimide substrate can be reduced and adhesive strength can be improved.

The particle size range of the core-shell organic powder is preferably 50-1000 nm; the mass fraction range of the core-shell type organic powder in the second bonding layer is 5-20%.

Wherein the core-shell type organic powder is fine particles mainly composed of propylene polymer or butadiene polymer, and is a polymer of unsaturated monomer with inner core layer forming rubber-like polymer, and shell layer is monomer or copolymer of methacrylate; specifically, the core-shell type organic powder comprises a core layer and a shell layer coated outside the core layer; wherein the core layer is at least one of (methyl) acrylic polymer and butadiene polymer; the shell layer is a methyl methacrylate monomer or a copolymer thereof.

The core layer is preferably selected from unsaturated monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (nitrogen-containing) (meth) acrylate, (meth) acrylonitrile, (meth) acrylamide, etc.; aromatic compounds such as styrene, α -methylstyrene and vinyltoluene; hydroxyl group-containing unsaturated monomers such as hydroxyethyl (meth) acrylate and hydroxymethyl (meth) acrylamide; (Meta) unsaturated acids, such as acrylic acid. Examples thereof include at least one of butylamine and isoprene. Typical examples of the polymer include poly (meth) acrylate rubber, polybutene rubber, polyisoprene rubber, polyvinyl chloride, styrene-butene rubber, styrene-butene-styrene rubber and styrene-isoprene-styrene rubber; examples thereof include styrene-butene rubber, styrene-ethylene rubber and ethylene-propylene rubber; among these, at least one of poly (meth) acrylate rubber, polybutene rubber, polyisoprene rubber and styrene-butadiene rubber is particularly preferable.

The methyl methacrylate polymer forming the shell layer is polymerized from methyl methacrylate monomer and other lower alkyl methacrylate (e.g., ethyl methacrylate, butyl methacrylate, styrene or a mixture thereof).

The core-shell organic powder can be prepared by itself or purchased directly; for example, (core) butyl acrylate/(shell) methacrylate organic particles, having an average particle size of 500nm, manufactured by DOW under the product name PARALOID EXL-2313; (core) butadiene-styrene/(shell) methacrylate organic particles having an average particle diameter of 200nm, manufactured by DOW company under the product name PARALOID EXL-2655; (core) butadiene/(shell) methacrylate-styrene organic particles having an average particle diameter of 180nm, produced by KANEKA, Inc. under the product name KANE ACE M-732; (core) butyl acrylate/(shell) polystyrene organic particles having an average particle diameter of 500nm, manufactured by AICA under the product name STAFILOID AC-3355.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Example 1

S1: 40 wt% of a urethane resin (Desmocoll406, manufactured by Covestro corporation), 15 wt% of a fluorene acrylate (TR-FR-301, manufactured by TRONLY corporation), 35 wt% of a urethane acrylate (SartomerCN9782, manufactured by ARKEMA corporation), 1 wt% of a phosphate acrylate (Sartomer SR9050, manufactured by ARKEMA corporation), 1 wt% of an acrylic silane coupling agent (A-171, manufactured by MOMENTIVE corporation), 3 wt% of an organic peroxide (LUPEROX331, manufactured by ARKEMA corporation), 3 wt% of a conductive particle (AUL 704, manufactured by Water chemical industries), 2 wt% of an inorganic silica particle (AEROSIL R805: octylsilane-treated silica particle, 1 time of 12nm in particle size, manufactured by EVONIC corporation), was mixed, stirred with a rotary stirrer, applied to a PET film (25E-DG3, manufactured by CROS corporation) using a film coating machine (BEVS 8, BEVS 894, manufactured by BEVS 894. mu. m, drying in a drying oven at 60 ℃ for 5 minutes to obtain a first bonding layer;

s2: 40 wt% of a urethane resin (Desmocoll406, manufactured by Covestro corporation), 15 wt% of a fluorene acrylate (TR-FR-301, manufactured by TRONLY corporation), 35 wt% of a polyurethane (SartomerCN9782, manufactured by ARKEMA corporation), 1 wt% of a phosphate acrylate (Sartomer SR9050, manufactured by ARKEMA corporation), 1 wt% of an acrylic silane coupling agent (A-171, manufactured by MOMENTIVE corporation), 3 wt% of an organic peroxide (LUPEROX331, manufactured by ARKEMA corporation), 5 wt% of a core-shell type organic powder (PARALOID EXL 2313: average particle diameter 500nm, manufactured by DOW corporation), stirred with a self-rotating stirrer, coated on a PET film (50E-8811ASCHK, manufactured by ZACROS corporation) using a film coating machine (BEVS1818, manufactured by BEVS) to be 11 μm in thickness, and dried at 60 ℃ for 5 minutes to obtain a second adhesive layer;

s3: and (3) sticking the first adhesive layer and the second adhesive layer to obtain the circuit connection adhesive film with the thickness of 15 mu m.

Example 2

This example differs from example 1 in that 10 wt% of inorganic silica particles (AEROSIL R805: silica particles treated with octylsilane, 1-size 12nm, manufactured by EVONIC) were added in step S1; step S2, adding 20 wt% of core-shell type organic powder (PARALOID EXL 2313: average particle size 500nm, manufactured by DOW Co.); the thickness of the first adhesive layer 1 was 8 μm, and the thickness of the second adhesive layer 2 was 7 μm.

Example 3

This example is different from example 1 in that 2 wt% of inorganic silica particles (AEROSIL R805: silica particles treated with octylsilane and having a 1-order particle diameter of 12nm, manufactured by EVONIC) were added in step S1; in step S2, 20 wt% of core-shell type organic powder (PARALOID EXL 2313: average particle diameter 500nm, manufactured by DOW Co.) was added.

Example 4

In this example and example 1, 10 wt% of inorganic silica particles (AEROSIL R805: silica particles treated with octylsilane, 1-size 12nm, manufactured by EVONIC) were added in step S1; in step S2, 5 wt% of core-shell type organic powder (PARALOID EXL 2313: average particle diameter 500nm, manufactured by DOW Co., Ltd.) was added.

Comparative example 1

This comparative example is different from example 1 in that inorganic silica particles are not added in step S1 and core-shell type organic powder is not added in step S2; the thickness of the first adhesive layer 1 was 2 μm and the thickness of the second adhesive layer 2 was 13 μm.

Comparative example 2

This comparative example is different from example 1 in that 15 wt% of inorganic silica particles (AEROSIL R805: silica particles treated with octylsilane and having a 1-order particle diameter of 12nm, manufactured by EVONIC) were added in step S1; step S2, adding 30 wt% of core-shell type organic powder (PARALOID EXL 2313: average particle size 500nm, manufactured by DOW Co.); the thickness of the first adhesive layer 1 was 10 μm and the thickness of the second adhesive layer 2 was 5 μm.

The performance test of the circuit connection adhesive film prepared in each embodiment and the comparative example is carried out, and the specific test method is as follows:

measurement of linear expansion coefficient

The first adhesive layer 1 and the second adhesive layer 2 are individually stacked to a thickness of 30 to 33 μm, and then placed in an oven at 200 ℃ for 3 hours to be heat-cured. The heat-cured film was peeled off from the separator and cut into a size of 2mm × 30mm as a sample for measurement. Thermomechanical analysis was performed in a tensile test mode under a load condition of 20mm between chucks, a measurement temperature range of 50 to 200 ℃, a temperature rise rate of 5 ℃/min, and a cross-sectional pressure of 0.5MPa using a TMA apparatus (model TMA450, manufactured by tasinstruments), and a coefficient of linear expansion was determined. The results are shown in Table 1.

Second, manufacturing the circuit connection structure

A circuit connection adhesive film obtained by bonding the first adhesive layer 1 and the second adhesive layer 2 was cut into a size of 1.5mm × 50mm, and laminated on an ITO pattern glass substrate (40umP, Line/Space 1/1, 0.8mm thick) at 70 ℃/1MP/2sec using a bonding apparatus (model LD-02, manufactured by bridge fabrication); after peeling off the PET, the COF polyimide substrates (40umP, Line/Space 1/1, S' perflex base material) were temporarily fixed in alignment with each other, and connected at 170 ℃/3MPa/10sec using a thermocompression bonding apparatus (model BD-01, manufactured by bridge manufacturing), thereby obtaining a circuit connection structure.

Third, determination of connection resistance before environmental test

The connection resistance value at 1mA of the inter-terminal current was measured for the circuit connection structure using the 4-terminal method, and the connection resistance before the environmental test was obtained, and the test data are shown in table 2.

Fourthly, measuring the connection resistance after the environmental test

And putting the circuit connection structure in a high-temperature and high-humidity environment of 85 ℃/85% for 500 hours, taking out, recovering to room temperature, and measuring the connection resistance to obtain the connection resistance after the environmental test, wherein the test data is shown in table 2.

In the present invention, the connection resistance is judged to be NG at 3 Ω or more.

Table 1 table 2

As can be seen from the data in the above, the circuit connection adhesive film provided by the present invention does not peel off at the substrate interface when the glass substrate and the polyimide substrate are connected under heat and pressure, and can maintain good connection reliability even after a test is performed in a severe environment.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A circuit connection adhesive film is characterized by comprising a first adhesive layer and a second adhesive layer which are arranged in a stacked mode; wherein the content of the first and second substances,

2. The adhesive film for circuit connection according to claim 1, wherein the thickness of the first adhesive layer is 1 to 2 times the particle diameter of the conductive particles.

3. The circuit-connecting adhesive film of claim 1, wherein the first adhesive layer further comprises inorganic nanoparticles dispersed in the first adhesive layer.

4. The circuit-connecting adhesive film according to claim 3, wherein; the mass fraction range of the inorganic nanoparticles in the first bonding layer is 2-15%.

5. The circuit-connecting adhesive film according to claim 3, wherein the inorganic nanoparticles comprise inorganic silica particles.

6. The adhesive film for circuit connection according to claim 5, wherein the surface of the inorganic silica particles is subjected to hydrophobic treatment with at least one of dimethylsiloxane, trimethylsilyl group, and octylsilane.

7. The circuit-connecting adhesive film according to any one of claims 1 to 6, wherein the second adhesive layer further comprises core-shell type organic powder dispersed in the second adhesive layer.

8. The adhesive film for circuit connection according to claim 7, wherein the core-shell organic powder is present in the second adhesive layer in an amount ranging from 5% to 20% by mass.

9. The circuit-connecting adhesive film according to claim 7, wherein the core-shell type organic powder includes a core layer and a shell layer coated outside the core layer; the core layer is at least one of (methyl) acrylic polymer and butadiene polymer; the shell layer is a methyl methacrylate monomer or a copolymer thereof.

10. The circuit connecting adhesive film according to claim 9, wherein the core layer is at least one selected from the group consisting of poly (meth) acrylate rubber, polybutene rubber, polyisoprene rubber, and styrene-butadiene rubber.