KR100979947B1 - Anisotropic conductive film having a good adhesive property and circuit board using the same - Google Patents

Abstract

The present invention relates to an epoxy-based anisotropic conductive film with excellent curing reliability and optimized modulus of elasticity and elastic modulus, wherein the anisotropic conductive film according to the present invention has a curing behavior index (τ = [t _a / t _total ], τ: curing behavior). Index, t _a : time when the cure rate reaches 50%, t _total : total cure time) has a value between 0.2 and 0.5 or 0.3 and 0.75, and elastic modulus M ₂ at room temperature after completion of curing and elasticity before curing the ratio M ₂ / M ₁ of the modulus M ₁ is 10 or greater characterized.

Cure Behavior Index, Elastic Modulus, Anisotropic Conductive Film, ACF

Description

Anisotropic conductive film with excellent connection reliability and circuit connection structure using same {ANISOTROPIC CONDUCTIVE FILM HAVING A GOOD ADHESIVE PROPERTY AND CIRCUIT BOARD USING THE SAME}

The present invention relates to an anisotropic conductive film used for connecting circuit boards or electronic components such as IC chips and wiring boards, and a circuit connection structure using the same. More specifically, the curing rate and elastic modulus are optimized to improve connection reliability. It relates to an excellent anisotropic conductive film.

In order to electrically connect circuit boards or electronic components, such as an IC chip, and a circuit board, the anisotropic conductive film in which the electroconductive particle is disperse | distributed to the adhesive agent is used. In this case, the anisotropic conductive film is disposed between the electrodes facing each other, the electrodes are connected by heating and pressurization, and then electrically connected by making the conductive in the pressing direction. Such anisotropic conductive film is typically used for packaging LCD panels, printed circuit boards (PCBs), and driver ICs in LCD modules.

Currently, LCDs are applied to a wide range of applications from large panels for notebook PCs, monitors, and TVs to medium and small panels for mobile devices such as mobile phones, personal digital assistants, and games. Driver IC mounting is adopted. Driver IC mounting in LCDs uses an outer lead bonding (OLB) method or a printed circuit board (PCB) in which a driver IC is formed into a tape carrier package (TCP) or a chip on film (COF) and bonded to the LCD panel. PCB: PCB type is attached to the printed circuit board. In addition, in small and medium-sized LCDs such as mobile phones, a COG (Chip On Glass) method in which a driver IC is directly mounted on an LCD panel by an anisotropic conductive film is adopted.

As described above, connection reliability between the circuit boards and electronic components such as IC chips and the circuit board using an anisotropic conductive film is the most problematic. That is, in the anisotropic conductive film, excellent conduction reliability is required along with high adhesiveness.

Therefore, various efforts have been made in the past to improve the connection reliability of the anisotropic conductive film. Representative examples include attempting to change the structure, such as forming an anisotropic conductive film in multiple layers, or adjusting the type and composition ratio of the adhesive composition and the conductive particles.

However, in order to improve the connection reliability of the anisotropic conductive film, efforts to adjust the characteristic values of the anisotropic conductive adhesive itself, such as curing rate and elastic modulus, have not been found.

An object of the present invention is to find a key characteristic factor (indentation parameter, elastic modulus) that can influence the connection reliability of an anisotropic conductive film, and to obtain an optimal value of the characteristic factor found.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

The anisotropic conductive film is composed of a thermoplastic resin for forming a film, a thermosetting resin used as a binder, conductive particles, and a release film. The anisotropic conductive film is interposed between the circuit members opposing each other, and then the opposite circuit members are bonded to each other by thermocompression bonding. Electrically connected In addition, in the anisotropic conductive film, since the thermosetting resin inside adheres to the opposite circuit member as the curing proceeds due to heat and pressure, the properties after thermocompression greatly change depending on the curing behavior of the thermosetting resin.

That is, the thermosetting resin of the anisotropic conductive film has a property that the viscosity decreases as heat is applied and heat is applied above the active temperature of the curing agent to increase the viscosity as curing proceeds. In this way, when the viscosity of the thermosetting resin rises, when the viscosity becomes higher than the specific viscosity, the conductive particles are not pressed due to the lack of flowability. The said specific viscosity means the viscosity at the time when the hardening rate of a thermosetting resin reaches about 50%.

Therefore, it is possible to improve the connection reliability of the anisotropic conductive film by adjusting the time taken for the curing rate of the thermosetting resin to reach 50%.

In addition, when the pressure is removed after the anisotropic conductive film is thermally compressed between the members to be connected, the connection constituting reliability deteriorates when the resin constituting the anisotropic conductive film causes recovery. Therefore, the connection reliability of the anisotropic conductive film can be improved by adjusting the elastic modulus after curing of the anisotropic conductive film to an appropriate value with respect to the elastic modulus before curing.
Specifically, the present invention is an anisotropic conductive film which is mechanically and electrically connected to the semiconductor chip and the glass substrate by being interposed between the semiconductor chip and the glass substrate, and thermally compressed, the anisotropic conductive film is a thermoplastic resin for film formation, It consists of epoxy-type thermosetting resin, a hardening | curing agent, electroconductive particle, and a release film as a binder,
The hardening behavior index (τ) expressed by the following equation has a value between 0.2 and 0.5,
τ = [t _a / t _total ] (where τ: hardening behavior index, t _a : time when hardening rate reaches 50%, t _total : total hardening time)
Anisotropic conductive film, characterized in that the ratio M ₂ / M ₁ of the elastic modulus M ₂ at room temperature after completion of curing and the elastic modulus M ₁ before curing, and
The present invention relates to a circuit connection structure electrically and mechanically connected by thermocompression bonding between a semiconductor chip and a glass substrate via the anisotropic conductive film.
In addition, the present invention is an anisotropic conductive film which is interposed between the first circuit member and the second circuit member and thermally compressed using a cushioning material to mechanically and electrically connect the first circuit member and the second circuit member, wherein the anisotropic conductive film The conductive film is composed of a thermoplastic resin for forming a film, an epoxy-based thermosetting resin, a curing agent, conductive particles, and a release film as a binder,
The hardening behavior index (τ) expressed by the following equation has a value between 0.3 and 0.75,
τ = [t _a / t _total ] (where τ: hardening behavior index, t _a : time when hardening rate reaches 50%, t _total : total hardening time)
Anisotropic conductive film, characterized in that the ratio M ₂ / M ₁ of the elastic modulus M ₂ at room temperature after completion of curing and the elastic modulus M ₁ before curing, and
The present invention relates to a circuit connection structure electrically and mechanically connected by thermocompression bonding between the first circuit member and the second circuit member via the anisotropic conductive film.
Here, the first circuit member may be a COF or TCP, and the second circuit member may be a glass substrate or a printed circuit board.

The anisotropic conductive film according to the present invention realizes high adhesion and conduction reliability in electrically connecting circuit boards or electronic components such as IC chips and circuit boards.

Hereinafter, the present invention will be described in detail with reference to the drawings. In each of the drawings, the same reference numerals denote the same or equivalent components.

1 shows a state in which anisotropic conductive film 10 according to the present invention is interposed between circuit boards 20 and 30 facing each other.

The anisotropic conductive film 10 is made of a thermoplastic resin for forming a film, an epoxy-based thermosetting resin, a curing agent, conductive particles, and a release film as a binder, and other additives may be included as necessary.

Examples of the thermoplastic resin include polyvinyl butyral, polyvinyl formal, polyvinyl acetal, polyamide, phenoxy resin, styrene-butadiene-styrene block copolymer, carboxylated styrene-ethylene-butylene-styrene block copolymer, 30 to 60 weight% of polyacrylate resin etc. can be used.

As the thermosetting resin, an epoxy resin is preferable, and in particular, a bisphenol type epoxy resin, a novolak type epoxy resin, a biphenyl type epoxy resin, a dicyclopentadiene type epoxy resin, a naphthalene type epoxy resin, or the like may be used. ~ 70% by weight can be used.

As said hardening | curing agent, the hardening | curing agent for epoxy resins is preferable, In particular, it is preferable to use the latent hardening | curing agent which is excellent in storage stability and fast hardening rate. Specifically, imidazole type (imidazole, 2-ethyl imidazole, 2-phenyl-4-methyl imidazole, 2-dodecyl imidazole, 2-phenyl imidazole, 2-phenyl-4-methyl imidazole, 4 0.1 to 10% by weight of -methyl imidazole, etc.), a hydrazide system, a boron trifluoride-amine complex, a sulfonium salt, an amineimide, a salt of a polyamine, and dicyandiamide.

As the conductive particles, in the case of an anisotropic conductive film of an OLB method or a COG method, a gold-nickel coated polymer ball or a gold coated nickel ball may be used, and in the case of a PCB type anisotropic conductive film, a nickel ball may be used. .

In addition, coupling agents, tackifiers, and the like may additionally be used as additives.

The anisotropic conductive film having the above configuration has a curing behavior index described in detail below by changing the type or content of the thermoplastic resin, the type or content of the thermosetting resin, the type or content of the curing agent, and the type of the additive. ) And elastic modulus can be adjusted in various ways.

Hereinafter, the curing behavior index τ and the elastic modulus are introduced as an index indicating the connection reliability (adhesiveness, conduction reliability) of the epoxy anisotropic conductive film.

2 is a graph showing the change in viscosity with temperature of the anisotropic conductive film. Referring to the drawing, when the anisotropic conductive film receives heat, the viscosity decreases to a specific temperature and then the viscosity increases as curing begins. At this time, when the viscosity of the anisotropic conductive film exceeds a specific viscosity (η), the fluidity of the degree to which the conductive particles are pressed is not shown. That is, in the region A of FIG. 2, the anisotropic conductive film exhibits fluidity such that the conductive particles are pressed by thermocompression, but in the region B, the fluidity is inferior and the conductive particles are not sufficiently pressed. Therefore, the anisotropic conductive film should remain in area A of FIG. 2 until the conductive particles are sufficiently pressed.

In addition, the time when the anisotropic conductive film which shows the outstanding connection reliability reaches | attains the said specific viscosity ((eta)) can be defined as when the hardening rate reaches 50%. Therefore, even if the hardening rate of the anisotropic conductive film does not reach 50%, if the specific viscosity (η) is reached or if the specific viscosity (η) is not reached even if the curing rate is higher than 50%, both the adhesiveness and It may cause a problem in conduction reliability.

The hardening behavior of the anisotropic conductive film may be expressed by a hardening behavior index τ expressed by Equation 1 below.

τ = [t _a / t _total ]

Where τ is the curing behavior index and t _a is the time when the curing rate reaches 50%, t _total : Total curing time)

The inventors have found that it is possible to improve the connection reliability of the anisotropic conductive film by appropriately adjusting the value of the curing behavior index τ of the anisotropic conductive film.

That is, in the case of the COG method in which the anisotropic conductive film is directly interposed between the chip and the glass substrate, it is preferable that the curing behavior index (τ) of the anisotropic conductive film has a value of 0.2 or more and 0.5 or less in order to ensure excellent connection reliability. (Ie 0.2 ≤τ≤ 0.5)

If the hardening behavior index (τ) of the anisotropic conductive film used in the COG method is less than 0.2, indentation failure occurs because hardening is completed before the conductive particles are sufficiently pressed due to rapid hardening, and the hardening behavior index (τ) If) exceeds 0.5, connection reliability deteriorates due to recovery of the resin due to uncuring.

In addition, in the case of an OLB method using an anisotropic conductive film to bond a COF or TCP to a glass substrate, or a PCB method using an anisotropic conductive film to bond a COF or TCP to a printed circuit board (PCB), It is preferable that the curing behavior index τ has a value of 0.3 or more and 0.75 or less (that is, 0.3 ≦ τ ≦ 0.75).

 If the hardening behavior index (τ) of the anisotropic conductive film used in the OLB method or the PCB method is less than 0.3, indentation defects occur because hardening is completed before the conductive particles are sufficiently pressed due to rapid hardening, and the hardening behavior When the index τ exceeds 0.75, the connection reliability deteriorates due to the recovery of the resin due to uncuring.

In the case of the COG method, since heat and pressure are directly applied to the chip without using a buffer material, the amount of heat applied to the anisotropic conductive film is greater than that of the OLB method or the PCB method. Due to this, the curing of the anisotropic conductive film is also faster. On the other hand, in the case of the OLB method or the PCB method, since the thermal compression is performed through the buffer material, heat transfer is slow and curing is also slow.

3 is a graph showing a change in elastic modulus according to the temperature of the anisotropic conductive film. Referring to the drawings, as the temperature initially increases, the elastic modulus of the anisotropic conductive film decreases, but as the curing starts, the elastic modulus rises again. At this time, when the elastic modulus is relatively low after completion of the curing of the anisotropic conductive film, the recovery of the polymer resin occurs, causing indentation defects and poor connection reliability.

Therefore, the elastic modulus behavior of the anisotropic conductive film showing excellent connection reliability is expressed by Equation 2 below.

M ₂ / M ₁ ≥10

(M ₁ : elastic modulus of anisotropic conductive film before curing, M ₂ : elastic modulus of anisotropic conductive film at room temperature after completion of curing)

If the value of M ₂ / M ₁ is less than 10, the recovery of the polymer resin occurs when the pressure is removed after completion of curing, and the indentation characteristics deteriorate.

The curing behavior index (τ) and elastic modulus behavior (M ₂ / M ₁ ≥ 10) can be adjusted by changing the type and amount of the thermoplastic resin, thermosetting resin, curing agent, additives and the like constituting the anisotropic conductive film.

For example, when an anisotropic conductive film is prepared by selecting a curing agent having a low curing start temperature and a fast curing rate, the curing behavior index is lowered to 0.2 or 0.3 or less while the time to reach a curing rate of 50% is accelerated. On the other hand, when an anisotropic conductive film is prepared by selecting a curing agent having a high curing start temperature and a slow curing speed, the curing behavior index is increased to 0.5 or 0.75 or more as the time to reach a curing rate of 50% is delayed.

Therefore, the curing behavior index (τ) of the anisotropic conductive film can be adjusted to 0.2 to 0.5 or 0.3 to 0.75 only by using a curing agent having a different curing start temperature from the same conditions.

In addition, even when the same curing agent is used, if the amount is increased, the curing behavior index τ is increased, and if the amount is decreased, the curing behavior index τ is lowered.

Therefore, the curing behavior index (τ) of the anisotropic conductive film can be adjusted to 0.2 to 0.5 or 0.3 to 0.75 by adjusting the content of the curing agent under all conditions.

In addition, the epoxy resin corresponding to the thermosetting resin is appropriately changed (adjustment of the number and molecular weight of functional groups contained in the epoxy resin) or a thermoplastic resin having a radical curing retardation effect (for example, methacrylate-based, maleimide compound, unsaturated By using acrylic polyfunctional monomers such as polyester, acrylic acid, vinyl acetate, acrylonitrile, etc., the curing behavior index τ and elastic modulus behavior (M ₂ / M ₁ ≧ 10) can be controlled.

In general, as the number of functional groups contained in the epoxy resin increases, the reaction rate increases, the crosslinking density increases, and thus the curing behavior index (τ) is low, and the elastic modulus (M ₂ ) after curing is high. On the other hand, when the number of functional groups contained in the epoxy resin decreases, the curing behavior index τ increases, and the elastic modulus M ₂ decreases after the curing is completed.

In addition, the elastic modulus behavior can be adjusted by appropriately changing the thermoplastic resin added for film formation.

In addition, it is possible to adjust the curing behavior index (τ) and the elastic modulus behavior (M ₂ / M ₁ ≥ 10) using radical curing accelerators, chain transfer aids, molecular weight regulators, and the like, and thermoplastic resins constituting the anisotropic conductive film, and thermosetting properties. By adjusting the composition ratio of the resin and the curing agent, the curing behavior index τ and the elastic modulus behavior (M ₂ / M ₁ ≧ 10) can be controlled.

Hereinafter, a plurality of anisotropic conductive films exhibiting various curing behavior indexes (τ) and elastic modulus behaviors (M ₂ / M ₁ ) are prepared, and the indentation characteristics and the connection resistance characteristics of the anisotropic conductive films thus prepared are measured and Arranged in a table.

[Production of Anisotropic Conductive Film]

The adhesive composition which consists of a thermoplastic resin for film formation, an epoxy thermosetting resin as a binder, and a hardening | curing agent is melt | dissolved or disperse | distributed in an organic solvent, and also conductive particle is disperse | distributed, and the film coating solution is manufactured. The organic solvent used at this time is preferable because the mixed solvent of an aromatic hydrocarbon type and an oxygen type improves the solubility of a material. Subsequently, this solution is apply | coated to the transparent PET film which surface-treated the single side | surface using the tapping machine value, and an anisotropic conductive film is obtained by 70 degreeC hot air drying for 10 minutes.

[COG type circuit connection structure]

It is a figure for demonstrating the COG system connection process of bonding a chip and a glass substrate through an anisotropic conductive film.

As shown in the drawing, the anisotropic conductive film 10 prepared above is pressed on the glass substrate 31, and the chips 21 are disposed on the anisotropic conductive film so as to face each other using a heating bar 41. A circuit connection structure is fabricated by heating and pressing for 10 seconds at a temperature of 180 ° C. and 3 MPa.

At this time, the anisotropic conductive film used in the circuit connection structure is manufactured to have a curing behavior index (τ) and elastic modulus behavior (M ₂ / M ₁ ) as follows.

Example 1

Anisotropic conduction with a curing behavior index (τ) of 0.21, an initial elastic modulus (M ₁ ) of 2 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 4 × 10 ⁹ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 200) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Example 2

Anisotropic conduction with a curing behavior index (τ) of 0.26, initial elastic modulus (M ₁ ) of 1 × 10 ⁷ [Pa], and elastic modulus (M ₂ ) of 9 × 10 ⁸ [Pa] at room temperature after completion of curing A film (M ₂ / M ₁ = 90) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Example 3

Anisotropic conduction with a curing behavior index (τ) of 0.48, initial elastic modulus (M ₁ ) of 3 × 10 ⁷ [Pa], and elastic modulus (M ₂ ) of 5 × 10 ⁸ [Pa] at room temperature after completion of curing A film (M ₂ / M ₁ = 16.7) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 1

Curing behavior index (τ) is 0.11, initial elastic modulus (M ₁ ) is 5 × 10 ⁷ [Pa], and after completion of curing, anisotropic conductive modulus (M ₂ ) at room temperature is 7 × 10 ⁹ [Pa] A film (M ₂ / M ₁ = 140) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 2

Anisotropic conduction with a curing behavior index (τ) of 0.62, an initial elastic modulus (M ₁ ) of 1 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 9 × 10 ⁸ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 90) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 3

Curing behavior index (τ) is 0.74, initial elastic modulus (M ₁ ) is 7 × 10 ⁶ [Pa], and after completion of curing, anisotropic conductive modulus (M ₂ ) at room temperature is 6 × 10 ⁷ [Pa] A film (M ₂ / M ₁ = 8.57) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 4

Curing behavior index (τ) is 0.11, initial elastic modulus (M ₁ ) is 8 × 10 ⁶ [Pa], and after completion of curing, anisotropic conductive elastic modulus (M ₂ ) at room temperature is 7 × 10 ⁷ [Pa] A film (M ₂ / M ₁ = 8.75) was produced and this anisotropic conductive film was applied to the circuit connection structure.

(1) indentation and (2) conduction reliability test were performed on the circuit connection structure via the anisotropic conductive film produced through the above-described Examples and Comparative Examples, and the results are shown in Table 1.

(1) indentation test

When the electrode of the glass substrate bonded to the chip is an ITO transparent electrode, the conductive ball pressing phenomenon was observed through an optical microscope, and in the case of a chromium electrode, the DIC indentation was observed using a differential interference microscope.

At this time, if the deformation of the conductive ball is observed in the ITO transparent electrode, ○, if there is no deformation of the conductive ball, it is indicated by ×, and if the protrusion of the conductive ball is observed in the chromium electrode, ○, there is no protrusion of the conductive ball. In the case, X was indicated.

(2) conduction reliability test

The resistance after the aging for 500 hours at the temperature of 85 ° C. and the 85% relative humidity (Ω _a ) and the initial resistance before aging (Ω _i ) were measured using a multimeter, respectively.

At this time, when the resistance value ( _a ) after aging and the initial resistance value ( _i ) before aging were both less than 5 kV, it was represented as (circle), x when 5 kW or more, and "OPEN" when measurement was impossible.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Challenge Ball
pressed ○ ○ ○ × × × × DIC Indentation ○ ○ ○ × × × × Ω _i [Ω] 0.3 0.4 0.3 4.5 3.2 5.2 2.7 Ω _a [Ω] 1.2 1.3 1.3 25.0 OPEN OPEN OPEN Ω _a / Ω _i ○ ○ ○ × OPEN OPEN OPEN

As can be seen from Table 1, all of the anisotropic conductive films of Examples 1 to 3 exhibited excellent indentation phenomenon and conduction reliability. On the other hand, the anisotropic conductive film of Comparative Example 1 was not only bad indentation characteristics, but also the resistance value after aging showed more than five times the initial resistance value before aging. In addition, in the case of Comparative Examples 2 to 4, poor conduction was observed after aging.

Therefore, when the anisotropic conductive film has the same hardening behavior index (0.2≤τ≤0.5) and elastic modulus behavior (M ₂ / M ₁ ≥ 10) as in Examples 1 to 3, the adhesion and conduction reliability of the anisotropic conductive film It can be confirmed that this is excellent.

[OLB type circuit connection structure]

5 illustrates an OLB connection process for bonding COF or TCP to a glass substrate via an anisotropic conductive film.

As shown in the figure, the anisotropic conductive film 10 prepared above is pressed on the glass substrate 31, and the COF or TCP 22 is disposed on the anisotropic conductive film. Subsequently, the circuit connecting structure is heated and pressurized for 7 seconds at 180 ° C. and 3 MPa using a heating bar 41 through a buffer 42 made of 0.15T Teflon sheet on the COF or TCP 22. To produce.

At this time, the anisotropic conductive film used in the circuit connection structure is manufactured to have a curing behavior index (τ) and elastic modulus behavior (M ₂ / M ₁ ) as follows.

Example 1

Anisotropic conduction with a curing behavior index (τ) of 0.32, an initial elastic modulus (M ₁ ) of 1 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 3 × 10 ⁹ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 300) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Example 2

Anisotropic conduction with a curing behavior index (τ) of 0.41, an initial elastic modulus (M ₁ ) of 3 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 4 × 10 ⁸ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 13.3) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Example 3

Curing behavior index (τ) is 0.73, initial elastic modulus (M ₁ ) is 2 × 10 ⁷ [Pa], and after completion of curing, anisotropic conductive elastic modulus (M ₂ ) at room temperature is 5 × 10 ⁸ [Pa] A film (M ₂ / M ₁ = 25) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 1

Anisotropic conduction with a curing behavior index (τ) of 0.27, an initial elastic modulus (M ₁ ) of 4 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 7 × 10 ⁹ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 175) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 2

Curing behavior index (τ) is 0.79, initial elastic modulus (M ₁ ) is 9 × 10 ⁶ [Pa], and after completion of curing, anisotropic conductive elastic modulus (M ₂ ) at room temperature is 3 × 10 ⁸ [Pa]. A film (M ₂ / M ₁ = 33.3) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 3

Anisotropic conduction with a curing behavior index (τ) of 0.42, initial elastic modulus (M ₁ ) of 8 × 10 ⁶ [Pa], and elastic modulus (M ₂ ) of 7 × 10 ⁷ [Pa] at room temperature after completion of curing A film (M ₂ / M ₁ = 8.75) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 4

Anisotropic conduction with a curing behavior index (τ) of 0.27, initial elastic modulus (M ₁ ) of 9 × 10 ⁶ [Pa], and elastic modulus (M ₂ ) of 7 × 10 ⁷ [Pa] at room temperature after completion of curing A film (M ₂ / M ₁ = 7.78) was produced and this anisotropic conductive film was applied to the circuit connection structure.

(1) indentation and (2) conduction reliability test were performed on the circuit connection structure via the anisotropic conductive film produced through the above-described Examples and Comparative Examples, and the results are shown in Table 2.

(1) indentation test

When the electrode of the glass substrate bonded to the chip is an ITO transparent electrode, the conductive ball pressing phenomenon was observed through an optical microscope, and in the case of a chromium electrode, the DIC indentation was observed using a differential interference microscope.

At this time, if the deformation of the conductive ball is observed in the ITO transparent electrode, ○, if there is no deformation of the conductive ball, it is indicated by ×, and if the protrusion of the conductive ball is observed in the chromium electrode, ○, there is no protrusion of the conductive ball. In the case, X was indicated.

(2) conduction reliability test

The resistance after the aging for 500 hours at the temperature of 85 ° C. and the 85% relative humidity (Ω _a ) and the initial resistance before aging (Ω _i ) were measured using a multimeter, respectively.

At this time, when the resistance value ( _a ) after aging and the initial resistance value ( _i ) before aging were both less than 5 kV, it was represented as (circle), x when 5 kW or more, and "OPEN" when measurement was impossible.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Challenge Ball
pressed ○ ○ ○ × × × × DIC Indentation ○ ○ ○ × × × × Ω _i [Ω] 0.2 0.3 0.2 5.6 4.9 7.2 10.1 Ω _a [Ω] 1.2 1.3 1.3 53.1 OPEN OPEN OPEN Ω _a / Ω _i ○ ○ ○ × OPEN OPEN OPEN

As can be seen from Table 2, the anisotropic conductive films of Examples 1 to 3 all exhibited excellent indentation and conduction reliability. On the other hand, the anisotropic conductive film of Comparative Example 1 was not only poor indentation characteristics, but also the resistance value after aging showed 9 times or more than the initial resistance value before aging. In addition, in the case of Comparative Examples 2 to 4, poor conduction was observed after aging.

Therefore, when the hardening behavior index (0.3≤τ≤0.75) and the elastic modulus behavior (M ₂ / M ₁ ≥ 10) as in Examples 1 to 3, the adhesion and conduction reliability of the anisotropic conductive film is excellent. You can check it.

[PCB type circuit connection structure]

6 illustrates a PCB-type connection process of bonding COF or TCP to a printed circuit board through an anisotropic conductive film.

As shown in the figure, the anisotropic conductive film 10 prepared above is pressed on the printed circuit board 32, and the COF or TCP 22 is disposed on the anisotropic conductive film. Subsequently, the circuit connecting structure is heated and pressurized for 7 seconds at 180 ° C. and 3 MPa using a heating bar 41 through a buffer 42 made of 0.15T Teflon sheet on the COF or TCP 22. To produce.

At this time, the anisotropic conductive film used in the circuit connection structure is manufactured to have a curing behavior index (τ) and elastic modulus behavior (M ₂ / M ₁ ) as follows.

Example 1

Anisotropic conduction with a curing behavior index (τ) of 0.32, an initial elastic modulus (M ₁ ) of 1 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 3 × 10 ⁹ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 300) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Example 2

Anisotropic conduction with a curing behavior index (τ) of 0.41, an initial elastic modulus (M ₁ ) of 3 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 4 × 10 ⁸ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 13.3) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Example 3

Curing behavior index (τ) is 0.73, initial elastic modulus (M ₁ ) is 2 × 10 ⁷ [Pa], and after completion of curing, anisotropic conductive elastic modulus (M ₂ ) at room temperature is 5 × 10 ⁸ [Pa] A film (M ₂ / M ₁ = 25) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 1

Anisotropic conduction with a curing behavior index (τ) of 0.27, an initial elastic modulus (M ₁ ) of 4 × 10 ⁷ [Pa], and an elastic modulus (M ₂ ) of 7 × 10 ⁹ [Pa] at room temperature after completion of curing. A film (M ₂ / M ₁ = 175) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 2

Curing behavior index (τ) is 0.79, initial elastic modulus (M ₁ ) is 9 × 10 ⁶ [Pa], and after completion of curing, anisotropic conductive elastic modulus (M ₂ ) at room temperature is 3 × 10 ⁸ [Pa]. A film (M ₂ / M ₁ = 33.3) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 3

Anisotropic conduction with a curing behavior index (τ) of 0.42, initial elastic modulus (M ₁ ) of 8 × 10 ⁶ [Pa], and elastic modulus (M ₂ ) of 7 × 10 ⁷ [Pa] at room temperature after completion of curing A film (M ₂ / M ₁ = 8.75) was produced and this anisotropic conductive film was applied to the circuit connection structure.

Comparative Example 4

Anisotropic conduction with a curing behavior index (τ) of 0.27, initial elastic modulus (M ₁ ) of 9 × 10 ⁶ [Pa], and elastic modulus (M ₂ ) of 7 × 10 ⁷ [Pa] at room temperature after completion of curing A film (M ₂ / M ₁ = 7.78) was produced and this anisotropic conductive film was applied to the circuit connection structure.

(1) indentation and (2) conduction reliability test were performed on the circuit connection structure via the anisotropic conductive film produced through the above-described Examples and Comparative Examples, and the results are shown in Table 3.

(1) indentation test

When the electrode of the glass substrate bonded to the chip is an ITO transparent electrode, the conductive ball pressing phenomenon was observed through an optical microscope, and in the case of a chromium electrode, the DIC indentation was observed using a differential interference microscope.

At this time, if the deformation of the conductive ball is observed in the ITO transparent electrode, ○, if there is no deformation of the conductive ball, it is indicated by ×, and if the protrusion of the conductive ball is observed in the chromium electrode, ○, there is no protrusion of the conductive ball. In the case, X was indicated.

(2) conduction reliability test

The resistance after the aging for 500 hours at the temperature of 85 ° C. and the 85% relative humidity (Ω _a ) and the initial resistance before aging (Ω _i ) were measured using a multimeter, respectively.

At this time, when the resistance value ( _a ) after aging and the initial resistance value ( _i ) before aging were both less than 5 kV, it was represented as (circle), x when 5 kW or more, and "OPEN" when measurement was impossible.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 PCB Indentation ○ ○ ○ × × × × Ω _i [Ω] 0.4 0.4 0.3 5.0 4.3 5.7 3.9 Ω _a [Ω] 1.2 1.3 1.2 53.0 OPEN OPEN 29.1 Ω _a / Ω _i ○ ○ ○ × OPEN OPEN ×

As can be seen from Table 3, the anisotropic conductive films of Examples 1 to 3 all exhibited excellent indentation phenomenon and conduction reliability. On the other hand, the anisotropic conductive films of Comparative Examples 1 and 4 not only had poor indentation characteristics, but also exhibited a resistance value after aging of 9 times or more than the initial resistance value before aging. In addition, in the case of Comparative Example 2 and Comparative Example 3 showed poor conduction after aging.

Therefore, when the hardening behavior index (0.3≤τ≤0.75) and the elastic modulus behavior (M ₂ / M ₁ ≥ 10) as in Examples 1 to 3, the adhesion and conduction reliability of the anisotropic conductive film is excellent. You can check it.

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention, serve to further understand the technical spirit of the present invention. It should not be construed as limited to.

1 is a state diagram in which an anisotropic conductive film is interposed between opposing circuit members.

2 is a graph showing the change in viscosity with temperature of the anisotropic conductive film.

3 is a graph showing a change in elastic modulus according to the temperature of the anisotropic conductive film.

4 is a diagram illustrating a COG method of connecting a chip and a glass substrate through an anisotropic conductive film.

5 is an OLB connection process diagram for bonding COF or TCP to a glass substrate via an anisotropic conductive film.

FIG. 6 is a PCB process diagram of bonding COF or TCP to a printed circuit board through an anisotropic conductive film.

<Explanation of symbols for the main parts of the drawings>

10: anisotropic conductive film 31: glass substrate

32: printed circuit board 21: semiconductor chip

22: COF or TCP 41: Heating bar

42: cushioning material

Claims (14)

An anisotropic conductive film which is mechanically and electrically connected to the semiconductor chip and the glass substrate by being thermally compressed between the semiconductor chip and the glass substrate, The anisotropic conductive film is composed of a thermoplastic resin for forming a film, an epoxy-based thermosetting resin, a curing agent, conductive particles, and a release film as a binder, The hardening behavior index (τ) expressed by the following equation has a value between 0.2 and 0.5, τ = [t _a / t _total ] Where τ = curing behavior index, t _a : time when the curing rate reaches 50%, t _total : total curing time) Anisotropic conductive film, characterized in that the ratio M ₂ / M ₁ of the elastic modulus M ₂ at room temperature after the completion of curing and the elastic modulus M ₁ before curing. An anisotropic conductive film interposed between a first circuit member and a second circuit member and thermally compressed using a cushioning material to mechanically and electrically connect the first circuit member and the second circuit member.  The anisotropic conductive film is composed of a thermoplastic resin for forming a film, an epoxy-based thermosetting resin, a curing agent, conductive particles, and a release film as a binder, The hardening behavior index (τ) expressed by the following equation has a value between 0.3 and 0.75, τ = [t _a / t _total ] Where τ = curing behavior index, t _a : time when the curing rate reaches 50%, t _total : total curing time) Anisotropic conductive film, characterized in that the ratio M ₂ / M ₁ of the elastic modulus M ₂ at room temperature after the completion of curing and the elastic modulus M ₁ before curing. The method of claim 2, The first circuit member is COF or TCP, and the second circuit member is an anisotropic conductive film, characterized in that the glass substrate. The method of claim 2, The first circuit member is COF or TCP, and the second circuit member is an anisotropic conductive film, characterized in that the printed circuit board. delete delete delete delete delete delete A circuit connection structure electrically and mechanically connected between a semiconductor chip and a glass substrate by thermocompression bonding through the anisotropic conductive film of claim 1. A circuit connecting structure electrically and mechanically connected between a first circuit member and a second circuit member by thermocompression bonding through the anisotropic conductive film of claim 2. 13. The method of claim 12, And the first circuit member is COF or TCP, and the second circuit member is a glass substrate. 13. The method of claim 12, Wherein said first circuit member is a COF or TCP and said second circuit member is a printed circuit board.

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