JPH1161088A - Adhesive for connecting circuit member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive for connecting circuit members which does not increase the resistance at a connecting point, does not separate at the point and improves the reliability of connection by compounding an inorg. filler into an adhesive resin compsn. contg. an epoxy resin, an acrylic rubber, and a latent curative. SOLUTION: An adhesive resin compsn. is obtd. by compounding an epoxy resin with 15-40 wt.% acrylic rubber and a latent curative such as an imidazole- based one, a hydrazide-based one, a boron trifluoride-amine complex, a sulfonium salt, an amineimide, a polyamine salt. or dicyandiamide. This compsn. is further compounded with 5-200 pts.wt., pref. 7-70 pts.wt., still pref. 7-40 pts.wt., inorg. filler and if necessary 0.1-30 vol.%, pref. 0.2-15 vol.%, conductive particles having an average particle size (1-10 μm) larger than that of the inorg. filler, thus giving an adhesive for connecting circuit members which, after being cured, has an elastic modulus of 30-2, 000 MPa at 40 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for connecting circuit members, which is used for bonding a semiconductor chip to a substrate with an adhesive and electrically connecting both electrodes by, for example, a flip chip mounting method. About.

[0002]

2. Description of the Related Art In the field of semiconductor mounting, flip chip mounting, in which an IC chip is directly mounted on a printed circuit board or a flexible wiring board, has attracted attention as a new mounting mode corresponding to cost reduction and high precision. As a flip-chip mounting method, a method of providing a solder bump on a terminal of a chip and performing solder connection or a method of performing electrical connection via a conductive adhesive is known. In these methods, there is a problem in that when exposed to various environments, stress based on the difference in thermal expansion coefficient between the chip to be connected and the substrate is generated at the connection interface and connection reliability is reduced. For this reason, a method of injecting an epoxy resin-based underfill material into a gap between a chip and a substrate is generally studied for the purpose of reducing stress at a connection interface. However, there is a problem that the underfill injection step complicates the process and is disadvantageous in terms of productivity and cost. In order to solve such a problem, flip-chip mounting using an anisotropic conductive adhesive having anisotropic conductivity and a sealing function has recently attracted attention from the viewpoint of process simplicity.

[0003]

However, when a chip is directly mounted on a substrate via an anisotropic conductive adhesive, a stress based on a difference in thermal expansion coefficient between the chip and the substrate occurs in a connection portion under a temperature cycle test. Thermal shock test, PC
When a reliability test such as a T test or a solder bath immersion test is performed, there is a problem that the connection resistance increases and the adhesive is peeled off. In the case where a protruding electrode is formed on the connection terminal of the chip, stress based on the difference in thermal expansion coefficient between the chip and the substrate is concentrated on the interface between the protruding electrode and the chip in the reliability test, and the protruding electrode is separated from the interface of the chip electrode. However, there is a problem that conduction failure occurs. An object of the present invention is to provide a circuit board which does not increase the connection resistance at the connection portion or peels off the adhesive, and greatly improves the connection reliability.

[0004]

The adhesive for connecting circuit members of the present invention is interposed between circuit electrodes facing each other, presses the circuit electrodes facing each other, and electrically connects the electrodes in the pressing direction. An adhesive for connecting circuit members, comprising: an adhesive resin composition 1
It is characterized in that 5 to 200 parts by weight of an inorganic filler is contained in 00 parts by weight.

The average particle size of the inorganic filler is preferably 3 μm or less, and the adhesive contains 0.1 to 30% by volume of conductive particles having an average particle size larger than the average particle size of the inorganic filler. Is also good. The adhesive resin composition preferably has an elastic modulus at 40 ° C. after curing of 30 to 2000 MPa. The adhesive resin composition contains at least an epoxy resin, an acrylic rubber, and a latent curing agent, and is in the form of a film. Adhesives for connecting circuit members are preferred. Acrylic rubber having a glycidyl ether group in its molecule is used.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Circuit members used in the present invention include a semiconductor chip, a printed circuit board, and a flexible wiring board based on polyimide or polyester. On the electrode pads of the semiconductor chip and the substrate, the bumps formed by plating and the tips of the gold wires are melted with a torch or the like to form gold balls, and the balls are pressed on the electrode pads, and then the wires are cut. A protruding electrode such as a wire bump obtained by the above method can be provided and used as a connection terminal.

The adhesive resin composition used in the present invention includes epoxy resin and imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt,
A mixture of a latent curing agent such as an amine imide, a polyamine salt, and dicyandiamide is used.
An adhesive resin composition having an elastic modulus at 0 ° C. of 30 to 2000 MPa is preferred. For example, as an adhesive resin composition capable of obtaining good fluidity and high connection reliability at the time of connection, epoxy resin and imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, salt of polyamine, A mixture of a latent curing agent such as dicyandiamide has an elastic modulus at 40 ° C. after bonding of 30 to 2000 MPa.
An adhesive containing an acrylic rubber so that The elastic modulus of the adhesive film cured product is, for example, Rheology Co., Ltd. Rheospectra DVE-4 (pulling mode,
It can be measured using a frequency of 10 Hz and a temperature rise at 5 ° C./min).

The acrylic rubber used in the present invention includes a polymer or a copolymer containing at least one of acrylic acid, acrylic acid ester, methacrylic acid ester and acrylonitrile as a monomer component, and particularly contains a glycidyl ether group. A copolymer acrylic rubber containing glycidyl acrylate or glycidyl methacrylate is preferably used. The molecular weight of these acrylic rubbers is preferably 200,000 or more from the viewpoint of increasing the cohesive strength of the adhesive. The amount of acrylic rubber in the adhesive is 15 wt.
% Or less, the elastic modulus at 40 ° C. after bonding is 2000M.
If it exceeds Pa, and if it exceeds 40 wt%, the modulus of elasticity can be reduced, but the melt viscosity at the time of connection increases, and the removability of the molten adhesive between the connection electrode boundaries or at the interface between the connection electrode and the conductive particles decreases. As a result, it becomes impossible to secure electrical continuity between the connection electrodes or between the connection electrodes and the conductive particles. Therefore, the acrylic compounding amount is preferably 15 to 40% by weight. These acrylic rubbers compounded in the adhesive have a peak temperature of dielectric loss tangent due to the rubber component in the vicinity of 40 to 60 ° C., so that the elastic modulus of the adhesive can be reduced. In addition, a thermoplastic resin such as a phenoxy resin can be blended with the adhesive to facilitate film formation. In particular, the phenoxy resin is preferable because it has a similar structure to the epoxy resin, and has characteristics such as excellent compatibility with the epoxy resin and excellent adhesiveness. Film formation, at least these epoxy resin, acrylic rubber, phenoxy resin, an adhesive resin composition comprising a latent curing agent and conductive particles are dissolved or dispersed in an organic solvent and liquefied, and applied on a peelable substrate, This is done by removing the solvent below the activation temperature of the curing agent. As the solvent used at this time, a mixed solvent of an aromatic hydrocarbon type and an oxygen-containing type is preferable because the solubility of the material is improved.

The inorganic filler used in the present invention is not particularly limited, and examples thereof include fused silica,
Powders such as crystalline silica, calcium silicate, alumina, calcium carbonate and the like can be mentioned. The compounding amount of the inorganic filler is
The amount is 5 to 200 parts by weight with respect to 100 parts by weight of the adhesive resin composition. The larger the amount is, the more effective the lowering of the coefficient of thermal expansion is. Insufficient conduction due to a decrease in the exclusion of the agent occurs, and if the amount is small, the coefficient of thermal expansion cannot be sufficiently reduced.
It is preferably from 90 to 90 parts by weight, most preferably from 7 to 40 parts by weight. The inorganic filler can be used in an amount of 5 to less than 10 parts by weight based on 100 parts by weight of the adhesive resin composition. Also,
The average particle size is preferably 3 microns or less for the purpose of preventing poor conduction at the connection. In addition, it is desirable to use a spherical filler for the purpose of preventing a decrease in the fluidity of the resin at the time of connection and damage to the passivation film of the chip.

In the adhesive of the present invention, conductive particles can be dispersed for the purpose of positively imparting anisotropic conductivity in order to absorb height variations of chip bumps and circuit electrodes. In the present invention, the conductive particles are, for example, Au, Ni, A
g, Cu, W or metal particles such as solder or metal particles formed by plating or depositing a thin film of gold or palladium on the surface of these metal particles. Conductive particles provided with a conductive layer of Au, solder, or the like can be used. It is necessary that the particle size is smaller than the minimum distance between the electrodes of the substrate, and if there is a height variation of the electrodes, it is preferably larger than the height variation, and preferably larger than the average particle size of the inorganic filler. And 1 μm to 10 μm are preferred. Also,
The amount of conductive particles dispersed in the adhesive is 0.1 to 30% by volume.
And preferably 0.2 to 15% by volume. When the adhesive for connecting circuit members of the present invention is a film adhesive, the film thickness is not particularly limited, but is preferably larger than the gap between the first and second circuit members, and generally the gap is larger. On the other hand, a film thickness of 5 μm or more is desirable.

[0011]

【Example】

Example 1 50 g of a phenoxy resin and butyl acrylate (40
Parts), 125 g of an acrylic rubber (molecular weight: 850,000) obtained by copolymerizing ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidyl methacrylate (3 parts) was dissolved in 400 g of ethyl acetate to obtain a 30% solution. Next, 325 g of a liquid epoxy (epoxy equivalent: 185) containing a microcapsule-type latent curing agent was added to this solution and stirred, and fused silica (average particle diameter: 0.5 μm) was added to 100 parts by weight of the adhesive resin composition. 20 parts by weight, and further 2% by volume of nickel particles (diameter: 3 μm) were dispersed to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) using a roll coater.
It dried at 10 degreeC for 10 minutes, and produced the adhesive film 1 of 45 micrometers in thickness. The elastic modulus at 40 ° C. of this adhesive film 1 measured by a dynamic viscoelasticity measuring instrument using only the adhesive resin composition excluding the fused silica and nickel particles was 800 MPa. Next, gold bumps (area: 80 μm × 80 μm, space: 30 μm, height: 1) were formed by using the produced adhesive film 1.
Chip with 5 μm, 288 bumps (10 mm × 10
mm, thickness: 0.5 mm) and a Ni / Au plated Cu circuit printed circuit board were connected as shown below. Adhesive film (12mm x 12mm) is Ni / Au plated Cu
Circuit printed circuit board (electrode height: 20 μm, thickness: 0.8
mm) at 80 ° C and 10 kgf / cm ² ,
The separator was peeled off, and the bumps of the chip and the Ni / Au plated Cu circuit printed circuit board (thickness: 0.8 mm) were aligned. Then, at 180 ° C., 30 g / bump, 2
Heating and pressurizing were performed from above the chip under the condition of 0 second, and the main connection was performed. The connection resistance after the actual connection is 6 mΩ at the maximum per bump, 2 mΩ on average, and the insulation resistance is 10 ⁸ Ω or more.
0 cycle treatment, PCT test (121 ° C, 2 atm) 20
There was no change even after 10 hours of immersion in the solder bath at 260 ° C. for 0 hour, indicating good connection reliability.

Example 2 50 g of a phenoxy resin and butyl acrylate (40
Parts), ethyl acrylate (30 parts), 175 g of an acrylic rubber (molecular weight: 850,000) copolymerized with acrylonitrile (30 parts) and glycidyl methacrylate (3 parts) was dissolved in 525 g of ethyl acetate to obtain a 30% solution. Next, 275 g of a liquid epoxy (epoxy equivalent: 185) containing a microcapsule-type latent curing agent was added to this solution, and the mixture was stirred, and fused silica (average particle diameter: 0.5 μm) was added to 100 parts by weight of the adhesive resin composition. 40 parts by weight and further 2% by volume of nickel particles (diameter: 3 μm) were dispersed to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) using a roll coater.
It dried at 10 degreeC for 10 minutes, and produced the adhesive film 2 of 45 micrometers in thickness. The elastic modulus at 40 ° C. of this adhesive film 2 measured at 40 ° C. by a dynamic viscoelasticity measuring instrument only from the adhesive resin composition excluding the fused silica and nickel particles was 400 MPa. Next, gold bumps (area: 8
0 μm × 80 μm, space 30 μm, height: 15 μ
m, number of bumps 288) with chip (10mm x 10m)
m) and a Ni / Au plated Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) were connected as shown below. An adhesive film (12 mm x 12 mm) is applied to a Ni / Au plated Cu circuit printed circuit board at 80 ° C.
After attaching at kgf / cm ² , the separator was peeled off,
The bumps of the chip and the Ni / Au plated Cu circuit printed circuit board were aligned. Then, at 170 ° C., 30 g /
The main connection was performed by heating and pressing from above the chip under the conditions of the bump and 20 seconds. The connection resistance after this connection is up to 18 mΩ per bump, 8 mΩ on average, and the insulation resistance is 10 mΩ.
⁸ Ω or more, and these values are 1000 cycles of thermal shock test at −55 to 125 ° C., PCT test (121 ° C.,
There was no change even after immersion in a solder bath at 260 ° C. for 2 hours for 200 hours and good connection reliability was exhibited.

EXAMPLE 3 50 g of a phenoxy resin, butyl acrylate (40
Parts), ethyl acrylate (30 parts), acrylonitrile (30 parts), and 100 g of an acrylic rubber (molecular weight: 850,000) copolymerized with glycidyl methacrylate (3 parts) were dissolved in 350 g of ethyl acetate to obtain a 30% solution. Next, 350 g of a liquid epoxy (epoxy equivalent: 185) containing a microcapsule-type latent curing agent was added to this solution, and the mixture was stirred, and fused silica (average particle diameter: 0.5 μm) was added to 100 parts by weight of the adhesive resin composition. On the surface of a polystyrene core (diameter: 5 μm).
The conductive particles having the layer formed were dispersed at 5 vol% to obtain a film coating solution. This solution was separated with a separator (silicone-treated polyethylene terephthalate film, thickness 40).
μm) with a roll coater and dried at 100 ° C. for 10 minutes to produce an adhesive film 3 having a thickness of 45 μm. The modulus of elasticity at 40 ° C. of this adhesive film 3 measured by a dynamic viscoelasticity measuring instrument using only the adhesive resin composition excluding the fused silica and nickel particles was 1000 MPa. Next, using the produced adhesive film 3, gold bumps (area: 80 μm × 80 μm)
m, space 30 μm, height: 15 μm, number of bumps 28
8) With tip (10mm x 10mm, thickness: 0.5m)
m) and a Ni / Au plated Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) were connected as shown below. Adhesive film 3 (12mm x 12mm)
80 ° C, 1 on Ni / Au plated Cu circuit printed circuit board
After sticking at 0 kgf / cm ² , the separator was peeled off and the bumps of the chip and the Ni / Au plated Cu circuit printed circuit board were aligned. Then, at 170 ° C, 30
Heating and pressurizing were performed from above the chip under the conditions of g / bump and 20 seconds, and the actual connection was performed. Connection resistance is up to 5 mΩ per bump, 1.5 mΩ on average, and insulation resistance is 10 ⁸ Ω
These values are not changed even after 1000 cycles of thermal shock test at −55 to 125 ° C., 200 hours of PCT test (121 ° C., 2 atm), and 10 seconds after immersion in a solder bath at 260 ° C. Demonstrated connection reliability.

Example 4 50 g of a phenoxy resin and butyl acrylate (40
Parts), ethyl acrylate (30 parts), acrylonitrile (30 parts), and 100 g of an acrylic rubber (molecular weight: 850,000) copolymerized with glycidyl methacrylate (3 parts) were dissolved in 350 g of ethyl acetate to obtain a 30% solution. Next, 350 g of a liquid epoxy (epoxy equivalent: 185) containing a microcapsule-type latent curing agent was added to this solution, and the mixture was stirred and fused silica (average particle diameter: 0.5 μm).
20 parts by weight of m) with respect to 100 parts by weight of the adhesive resin composition, and 5 vol% of conductive particles having an Au layer formed on the surface of a polystyrene core (diameter: 5 μm) were dispersed at 5 vol% to give a film coating solution. Obtained. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) using a roll coater, and dried at 100 ° C. for 10 minutes to produce an adhesive film 4 having a thickness of 45 μm. This adhesive film 4 was measured with a dynamic viscoelasticity measuring device of only the adhesive resin composition excluding the fused silica and nickel particles.
The elastic modulus at ℃ was 1000 MPa. Next, a gold bump (area: 50 μm × 5
0 μm, 362 bumps, space: 20 μm, height: 1
5μm) with tip (1.7mm × 17mm, thickness:
0.5 mm) and a glass substrate with an ITO circuit (thickness: 1.1)
mm) was performed as shown below. After bonding the adhesive film 4 (12 mm × 12 mm) to a glass substrate with an ITO circuit at 80 ° C. and 10 kgf / cm ² , the separator was peeled off, and the bumps of the chip and the glass substrate with the ITO circuit were aligned. Then, heating and pressurization were performed from above the chip under the conditions of 180 ° C., 40 g / bump, and 20 seconds, and the actual connection was performed. The connection resistance is 150 mΩ at maximum per bump, 80 mΩ on average, and the insulation resistance is 10 ⁸ Ω or more. These values are 1000 cycles of thermal shock test at −40 to 100 ° C., and PCT test (105 ° C., 1. 2
There was no change even after 100 hours (atmospheric pressure), indicating good connection reliability.

EXAMPLE 5 50 g of a phenoxy resin and butyl acrylate (40
Parts), 125 g of an acrylic rubber (molecular weight: 850,000) obtained by copolymerizing ethyl acrylate (30 parts), acrylonitrile (30 parts) and glycidyl methacrylate (3 parts) was dissolved in 400 g of ethyl acetate to obtain a 30% solution. Next, 325 g of a liquid epoxy (epoxy equivalent: 185) containing a microcapsule-type latent curing agent was added to this solution, and the mixture was stirred and fused silica (average particle diameter: 0.5 μm)
60 parts by weight based on 100 parts by weight of the adhesive resin composition,
Further, 2 vol% of nickel particles (diameter: 3 μm) were dispersed to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 40 μm) using a roll coater.
After drying at 10 ° C. for 10 minutes, an adhesive film 5 having a thickness of 45 μm was prepared. The elastic modulus at 40 ° C. of this adhesive film 5 measured by a dynamic viscoelasticity measuring instrument using only the adhesive resin composition excluding the fused silica and nickel particles was 800 MPa. Next, a bumpless chip (1
0 mm x 10 mm, thickness: 0.5 mm, pad electrode: A
1, pad diameter: 120 μm) and Ni / Au plated Cu bumps on the circuit (diameter: 100 μm, space 50 μm,
Height: 15 μm, number of bumps 200) Ni / A formed
The connection of the u-plated Cu circuit printed circuit board was performed as shown below. Adhesive film 5 (12 mm x 12 mm)
i / Au plated Cu circuit printed circuit board (electrode height: 20
μm, thickness: 0.8 mm) at 80 ° C, 10 kgf / cm
After attaching in step ² , the separator is peeled off, and the Al
The positioning of the pad and the Ni / Au-plated Cu circuit printed circuit board (thickness: 0.8 mm) with the Ni / Au-plated Cu bump was performed. Then, at 180 ° C., 30 g / bump, 2
Heating and pressurizing were performed from above the chip under the condition of 0 second, and the main connection was performed. The connection resistance after this connection is ⁸ mΩ at the maximum per bump, 4 mΩ on average, and the insulation resistance is 10 ⁸ Ω or more. These values are the values of the thermal shock test at −55 to 125 ° C. 100
0 cycle treatment, PCT test (121 ° C, 2 atm) 20
There was no change even after 10 hours of immersion in the solder bath at 260 ° C. for 0 hour, indicating good connection reliability.

[0016]

According to the adhesive of the present invention, since the coefficient of thermal expansion is not large unlike the conventional adhesive, the chip and the ACF
In addition to being able to relieve stress at the interface, when the elastic modulus at 40 ° C. of the adhesive resin composition is 30 to 2000 MPa, thermal shock and PC
Since the stress generated in a reliability test such as T or solder bath immersion test can be absorbed, there is no increase in connection resistance at the connection portion and no peeling of the adhesive after the reliability test, and the connection reliability is greatly improved. Further, since the adhesive of the present invention has a small coefficient of thermal expansion and can relieve stress at the interface between the chip and the ACF, when the chip and the substrate are connected via the adhesive, the electrode pad of the chip is provided with a protruding electrode. ,
Peeling of the protruding electrode from the electrode pad under the temperature cycle test can be greatly reduced. Therefore, the adhesive of the present invention is suitable for electrically connecting the LCD panel and TAB, the TAB and the flexible circuit board, the LCD panel and the IC chip, and the IC chip and the printed board only in the pressing direction at the time of connection. Used.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C09J 163/00 C09J 163/00 H01L 21/52 H01L 21/52 E 21/60 311 21/60 311S (72) Inventor Kazuhiro Isaka 48 Wadai, Tsukuba, Ibaraki Prefecture, Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor Osamu Watanabe 48 Wadadai, Tsukuba, Ibaraki Prefecture, Tsukuba Development Laboratory, Hitachi Chemical Co., Ltd. Wada48 Hitachi Chemical Co., Ltd. Tsukuba Development Laboratory

Claims (7)

[Claims] 1. An adhesive for connecting circuit members, which is interposed between opposing circuit electrodes and pressurizes the opposing circuit electrodes to electrically connect the electrodes in the pressing direction. An adhesive for connecting circuit members, wherein 5 to 200 parts by weight of an inorganic filler is contained in parts by weight. 2. The adhesive according to claim 1, wherein the inorganic filler has an average particle size of 3 μm or less. 3. The adhesive for connecting circuit members according to claim 1, wherein the adhesive contains 0.1 to 30% by volume of conductive particles having an average particle size larger than the average particle size of the inorganic filler. . 4. The adhesive according to claim 1, wherein the adhesive resin composition has an elastic modulus at 40 ° C. after curing of 30 to 2000 MPa. 5. An adhesive resin composition comprising at least an epoxy resin, an acrylic rubber, and a latent curing agent.
4. The adhesive for connecting circuit members according to any one of Items 4 to 4. 6. The adhesive according to claim 5, wherein the acrylic rubber contains a glycidyl ether group in its molecule. 7. The adhesive for connecting circuit members according to claim 1, wherein the adhesive is in the form of a film.