JP4385488B2 - Film adhesive for circuit connection - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film-like adhesive for circuit connection used for connecting an electronic component such as an IC chip and a wiring board.
[0002]
[Prior art]
When electrically connecting an electronic component such as an IC chip and a circuit board, an anisotropic conductive adhesive in which an adhesive or conductive particles are dispersed is used. In other words, these adhesives are arranged between the electrodes facing each other, and the electrodes are connected to each other by heat and pressure, and then electrically connected by giving conductivity in the pressing direction. it can. For example, JP-A-3-16147 proposes an adhesive for circuit connection based on an epoxy resin.
[0003]
[Problems to be solved by the invention]
Conventional film-like adhesive for circuit connection has low fluidity of adhesive during heating and pressurization, so that adhesive oozes out between the electronic component and the wiring board during the bonding process (hereinafter referred to as fillet) Bubbles inside remained without being defoamed, and sufficient moisture resistance and mechanical strength could not be maintained, resulting in a problem that reliability was lowered in a high temperature and high humidity test and a thermal shock test.
The present invention eliminates the bubbles in the adhesive that have exuded to the outside during heating and pressurization, maintains the moisture resistance and mechanical strength based thereon, and is excellent in reliability in high temperature and high humidity tests and thermal shock tests. An adhesive is provided.
[0004]
[Means for Solving the Problems]
The film-like adhesive for circuit connection of the present invention is a bisphenol-type liquid epoxy resin, film formation, in a heat-adhesive adhesive that electrically connects circuit electrodes facing each other by heating and pressurizing. The material and the latent curing agent are contained, cut into a thickness of 40 μm and a size of 5 × 5 mm, and a condition of 180 ° C., 20 seconds, 24.5 N (2.5 kgf) between glass substrates of a size of 15 × 15 mm The ratio (B / A) between the area (A) before bonding and the area (B) after bonding when heated and pressurized in (3) is 3.5 to 7.0 times. Examples of the bisphenol type liquid epoxy resin include bisphenol A type epoxy resins. Moreover, a phenoxy resin is mentioned as said film forming material. In the adhesive, 0.2 to 15% by volume of conductive particles can be dispersed.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The adhesive of the present invention is characterized in that the area after bonding is 3.5 to 7.0 times the area before bonding. If the area ratio is less than 3.5 times, the flowability is low, and bubbles generated in the fillet cannot be removed and remain, so that sufficient moisture resistance and mechanical strength cannot be maintained, and connection reliability is lowered. To do. On the other hand, if it exceeds 7.0, bubbles do not remain in the fillet, but bubbles are likely to remain between the electronic component and the wiring board, and sufficient moisture resistance and mechanical strength cannot be maintained.
The ratio of the area before and after bonding of the adhesive in the present invention is that a 40 μm-thick adhesive is cut into a size of 5 × 5 mm and a glass substrate with a size of 15 × 15 mm (Corning Corporation, # 7059, thickness 0. 7 mm), the ratio (B / A) of the area before bonding (A) and the area after bonding (B) when heated and pressed under the conditions of 180 ° C., 20 seconds, and 24.5 N (2.5 kgf) Is shown.
The adhesive used in the present invention preferably contains an epoxy resin, a film forming material, and a latent curing material.
[0006]
Epoxy resins used in the present invention is a bisphenol type epoxy resins derived epichlorohydrin and Bisufu E Bruno Lumpur A and F, from AD or the like. In addition, as an epoxy resin , an epoxy novolak resin derived from epichlorohydrin and phenol novolak or cresol novolak, a naphthalene epoxy resin having a skeleton containing a naphthalene ring, glycidylamine, glycidyl ether, biphenyl, alicyclic, etc. within one molecule it is also possible to use such various epoxy compounds having two or more glycidyl groups alone or in combination of two or more. For these epoxy resins, it is preferable to use a high-purity product in which impurity ions (Na ⁺ , Cl ^−, etc.) and hydrolyzable chlorine are reduced to 300 ppm or less to prevent electron migration.
[0007]
As the film forming material used in the present invention, thermoplastic resins such as phenoxy resin, polyester resin, and polyamide resin can be used. In particular, a phenoxy resin is preferable because it has a similar structure to an epoxy resin and has characteristics such as excellent compatibility with an epoxy resin and excellent adhesion.
[0008]
As the latent curing material used in the present invention, imidazole, hydrazide, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, dicyandiamide, and the like can be used.
[0009]
The film is formed by liquefying an adhesive composition composed of at least an epoxy resin, a film forming material, and a latent curing material in an organic solvent, and applying the composition on a peelable substrate with a roll coater or the like. This is done by removing the solvent below the activation temperature. The solvent used at this time is preferably an aromatic hydrocarbon-based and oxygen-containing mixed solvent because the solubility of the material is improved.
[0010]
In the adhesive of the present invention, conductive particles can be mixed and dispersed for the purpose of positively imparting anisotropic conductivity in order to absorb the height variation of the bumps of the chip and the substrate electrodes. In the present invention, the conductive particles are, for example, metal particles such as Au, Ag, Cu, and solder, and a polymer spherical core material such as polystyrene provided with a conductive layer such as Ni, Cu, Au, and solder. More preferred. Furthermore, a surface layer of Sn, Au, solder or the like can be formed on the surface of the conductive particles. The particle size needs to be smaller than the minimum distance between the electrodes of the substrate, and when there is a variation in the height of the electrodes, it is preferably larger than the variation in height, and preferably 1 to 10 μm. Moreover, the quantity of the electroconductive particle disperse | distributed to an adhesive agent is 0.1-30 volume%, Preferably it is 0.2-15 volume%.
[0011]
The adhesive layer can be multilayered with a film adhesive. For example, an anisotropic conductive film filled with conductive particles for imparting anisotropic conductivity and an adhesive film filled with conductive particles and a two-layer anisotropic conductive film laminated with an adhesive layer not filled with conductive particles An anisotropic conductive film having a three-layer structure in which adhesive layers not filled with conductive particles are laminated on both sides can be used. Since these multilayered anisotropic conductive films can efficiently capture conductive particles on the connection electrodes, they are advantageous for narrow pitch connection.
[0012]
In the present invention, as the circuit member, a chip component such as a semiconductor chip, a resistor chip, a capacitor chip, a printed board, a substrate such as a flexible wiring board based on polyimide or polyester, and the like are used.
[0013]
According to the film-like adhesive for circuit connection of the present invention, since the fluidity of the adhesive at the time of heating and pressurization is high, bubbles generated in the fillet during the bonding process are quickly defoamed, and in the fillet after curing No bubbles remain on the surface, and it is possible to prevent a decrease in moisture resistance and mechanical strength due to the bubbles.
[0014]
【Example】
(Example 1)
30 g of phenoxy resin (PKHC, manufactured by Union Carbide) was dissolved in 45 g of a mixed solvent of toluene and ethyl acetate (mixing weight ratio 1: 1) to obtain a 40 wt% solution. Next, 40 g of a liquid epoxy resin (YL980 manufactured by Yuka Shell Epoxy Co., Ltd.) and 30 g of a liquid epoxy (epoxy equivalent 185, manufactured by Asahi Kasei Kogyo Co., Ltd., NovaCure HX-3941) containing a microcapsule type latent curing material are added, The mixture was further stirred, and nickel particles (diameter 3 μm) were dispersed by 1% by volume to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 50 μm) with a roll coater, and dried at 80 ° C. for 10 minutes to produce an adhesive film having a thickness of 40 μm. This adhesive film was cut to a size of 5 × 5 mm, and it was 180 ° C., 20 seconds, 24.5 N (2.5 kgf) between 15 × 15 mm glass substrates (Corning Corp., # 7059, thickness 0.7 mm). The area after bonding was 3.7 times the area before bonding.
Next, using the prepared adhesive film, Ni (on a size: 10 × 10 mm, thickness: 500 μm) with a gold bump (area: 100 × 100 μm, space: 100 μm, height: 15 μm, number of bumps: 186) and Ni The connection of Cu circuit printed circuit board with / Au plating was performed as shown below. Adhesive film (12 x 12 mm) is attached to Ni / Au plated Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 90 ° C., 0.98 MPa (10 kgf / cm ² ) for 5 seconds. Then, the separator was peeled off, and the bumps of the chip and the Ni / Au plated Cu circuit printed board were aligned. Next, the main connection was performed by heating and pressing from above the chip under the conditions of 180 ° C., 0.98 N / bump (100 gf / bump), and 20 seconds. When the inside of the fillet after this connection was observed with a microscope, no bubbles were observed. In addition, the connection resistance after this connection is 15 mΩ at the maximum per bump, the average is 4 mΩ, and the insulation resistance is 10 ⁸ Ω or more. These values are the thermal shock test 1000 cycle treatment at −55 to 125 ° C., the PCT test ( There was no change in the IR reflow test at a temperature of 121 ° C. and 0.2 MPa (2 atm) for 200 hours and a peak temperature of 240 ° C., indicating good connection reliability.
[0015]
(Example 2)
30 g of phenoxy resin (manufactured by Union Carbide, PKHC) was dissolved in 45 g of a mixed solvent of toluene and ethyl acetate (mixing ratio 1: 1) to obtain a 40 wt% solution. Next, 50 g of a liquid epoxy resin (YL980, manufactured by Yuka Shell Engineering Poxy Co., Ltd.) and 20 g of a liquid epoxy (epoxy equivalent 185, manufactured by Asahi Kasei Kogyo Co., Ltd., NovaCure HX-3941) containing a microcapsule type latent hardener are added The mixture was stirred and further nickel particles (diameter 3 μm) were dispersed by 1% by volume to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 50 μm) with a roll coater, and dried at 80 ° C. for 10 minutes to produce an adhesive film having a thickness of 40 μm. This adhesive film was cut out to a size of 5 × 5 mm, and it was 180 ° C., 20 seconds, 24.5 N (2.5 kgf) between 15 × 15 mm glass substrates (Corning Corp., # 7059, thickness 0.7 mm). The area after bonding was 4.3 times as large as the area before bonding.
Next, using the produced adhesive film, a chip (size: 10 × 10 mm, thickness: 500 μm) with gold bumps (area: 100 × 100 μm, space: 100 μm, height: 15 μm, number of bumps: 186) and Ni / The connection of the Au plated Cu circuit printed circuit board was performed as follows. Adhesive film (12 x 12 mm) is applied to Ni / Au-attached Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 90 ° C. and 0.98 MPa (10 kgf / cm ² ) for 5 seconds. After attaching, the separator was peeled off, and the chip bump and the Ni / Au plated Cu circuit printed circuit board were aligned. Subsequently, heating and pressurization were carried out from above the chip under the conditions of 180 ° C., 0.98 N / bump (100 gf / bump), and 20 seconds to make the main connection. No bubbles were observed when the inside of the fillet after this connection was observed with a microscope. Moreover, the connection resistance after this connection is 16 mΩ at the maximum per bump, 3 mΩ on average, and the insulation resistance is 10 ⁸ Ω or more. These values are the thermal shock test at −55 to 125 ° C., 1000 cycle treatment, PCT test (121 ° C., 0.2 MPa (2 atm)) There was no change in the IR reflow test at a peak temperature of 240 ° C. for 200 hours, and good connection reliability was shown.
[0016]
(Example 3) 20 g of a phenoxy resin (PKHC, manufactured by Union Carbide) was dissolved in 30 g of a mixed solvent of toluene and ethyl acetate (mixing weight ratio 1: 1) to obtain a 40 wt% solution. Next, 60 g of liquid epoxy resin (YL980, manufactured by Yuka Shell Epoxy Co., Ltd.) and 20 g of liquid epoxy (epoxy equivalent 185, manufactured by Asahi Kasei Kogyo Co., Ltd., Novacure HX-3941) containing a microcapsule type latent curing material are added, The mixture was further stirred, and nickel particles (diameter 3 μm) were dispersed by 1% by volume to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 50 μm) with a roll coater, and dried at 80 ° C. for 10 minutes to produce an adhesive film having a thickness of 40 μm. This adhesive film was cut out to a size of 5 × 5 mm, and it was 180 ° C., 20 seconds, 24.5 N (2.5 kgf) between 15 × 15 mm glass substrates (Corning Corp., # 7059, thickness 0.7 mm). The area after bonding was 6.5 times the area before bonding. Next, using the produced adhesive film, a chip (size: 10 × 10 mm, thickness: 500 μm) with gold bumps (area: 100 × 100 μm, space: 100 μm, height: 15 μm, number of bumps: 186) and Ni / The connection of the Au plated Cu circuit printed circuit board was performed as shown below. Adhesive film (12 x 12 mm) is attached to Ni / Au plated Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 90 ° C. and 0.98 MPa (10 kgf / cm ² ) for 5 seconds. Then, the separator was peeled off, and the bumps of the chip and the Ni / Au plated Cu circuit printed board were aligned. Next, the main connection was performed by heating and pressing from above the chip under the conditions of 180 ° C., 0.98 N / bump (100 gf / bump), and 20 seconds. When the inside of the fillet after this connection was observed with a microscope, no bubbles were observed. In addition, the connection resistance after this connection is 13 mΩ at the maximum per bump, the average is 5 mΩ, and the insulation resistance is 10 ⁸ Ω or more. These values are the thermal shock test 1000 cycle treatment at −55 to 125 ° C., the PCT test ( There was no change in the IR reflow test at 121 ° C., 0.2 MPa (2 atm) for 200 hours and a peak temperature of 240 ° C., indicating good connection reliability.
[0017]
Comparative Example 1 40 g of a phenoxy resin (PKHC, manufactured by Union Carbide) was dissolved in 60 g of a mixed solvent of toluene and ethyl acetate (mixing weight ratio 1: 1) to obtain a 40 wt% solution. Next, 20 g of a liquid epoxy resin (YL980 manufactured by Yuka Shell Epoxy Co., Ltd.) and 40 g of a liquid epoxy (epoxy equivalent 185, manufactured by Asahi Kasei Kogyo Co., Ltd., Novacure HX-3941) containing a microcapsule type latent curing material are added, The mixture was further stirred, and nickel particles (diameter 3 μm) were dispersed by 1% by volume to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 50 μm) with a roll coater, and dried at 80 ° C. for 10 minutes to produce an adhesive film having a thickness of 40 μm. This adhesive film was cut out to a size of 5 × 5 mm, and it was 180 ° C., 20 seconds, 24.5 N (2.5 kgf) between 15 × 15 mm glass substrates (Corning Corp., # 7059, thickness 0.7 mm). When heated and pressurized under the conditions of), the area after bonding is the area before bonding 2. It was 5 times . Next, using the produced adhesive film, a chip (size: 10 × 10 mm, thickness: 500 μm) with gold bumps (area: 100 × 100 mm, space: 100 μm, height: 15 μm, number of bumps: 186) and Ni / The connection of the Au plated Cu circuit printed circuit board was performed as shown below. Adhesive film (12 x 12 mm) is applied to Ni / Au-attached Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 90 ° C. and 0.98 MPa (10 kgf / cm ² ) for 5 seconds. After attaching, the separator was peeled off, and the bumps of the chip and the Ni / Au plated Cu circuit printed circuit board were aligned. Subsequently, heating and pressurization were performed from above the chip under the conditions of 180 ° C., 0.98 N bumps (100 gf / bump), and 20 seconds to perform the main connection. When the inside of the fillet after this connection was observed with a microscope, a large number of bubbles were observed. In addition, the connection resistance after this connection is 15 mΩ at the maximum per bump, the average is ⁸ mΩ, and the insulation resistance is 10 ⁸ Ω or more. These values are the thermal shock test at −55 to 125 ° C., 1000 cycles treatment, PCT test (121 ° C., 0.2 MPa (2 atm)) 200 hours, In an IR reflow test at a peak temperature of 240 ° C., electrical continuity was poor. As a result of cross-sectional observation of the connection part, interface peeling was observed in a part of the connection part with poor conduction. Moreover, when the connection part was observed with the infrared microscope, corrosion was observed in a part of the aluminum pad.
[0018]
(Comparative Example 2)
15 g of phenoxy resin (PKHC, manufactured by Union Carbide) was dissolved in 22.5 g of a mixed solvent of toluene and ethyl acetate (mixing weight ratio 1: 1) to obtain a 40 wt% solution. Next, 65 g of liquid epoxy resin (YL980, manufactured by Yuka Shell Epoxy Co., Ltd.) and 20 g of liquid epoxy (epoxy equivalent 185, manufactured by Asahi Kasei Kogyo Co., Ltd., NovaCure HX-3941) containing a microcapsule type latent curing material are added, The mixture was further stirred, and nickel particles (diameter 3 μm) were dispersed by 1% by volume to obtain a film coating solution. This solution was applied to a separator (silicone-treated polyethylene terephthalate film, thickness 50 μm) with a roll coater, and dried at 80 ° C. for 10 minutes to produce an adhesive film having a thickness of 40 μm. This adhesive film was cut out to a size of 5 × 5 mm, and it was 180 ° C., 20 seconds, 24.5 N (2.5 kgf) between 15 × 15 mm glass substrates (Corning Corp., # 7059, thickness 0.7 mm). The area after bonding was 8.0 times the area before bonding.
Next, using the produced adhesive film, a chip (size: 10 × 10 mm, thickness: 500 μm) with gold bumps (area: 100 × 100 μm, space: 100 μm, height: 15 μm, banff number: 186) and Ni / The connection of the Au plated Cu circuit printed circuit board was performed as follows. Adhesive film (12 x 12 mm) is applied to Ni / Au-attached Cu circuit printed circuit board (electrode height: 20 μm, thickness: 0.8 mm) at 90 ° C. and 0.98 MPa (10 kgf / cm ² ) for 5 seconds. After attaching, the separator was peeled off, and the bumps of the chip and the Ni / Au plated Cu circuit printed circuit board were aligned. Next, the main connection was performed by heating and pressing from above the chip under the conditions of 180 ° C., 0.98 N / bump (100 gf / bump), and 20 seconds. When the inside of the fillet after this connection was observed with a microscope, no bubbles were observed. The connection resistance after this connection is a maximum of 15 mΩ per bump, an average of 9 mΩ, and an insulation resistance of 10 ⁸ Ω or more. These values are the thermal shock test at −55 to 125 ° C., 1000 cycle treatment, PCT test (121 In an IR reflow test at 200 ° C. and 0.2 MPa (2 atm) for 200 hours and a peak temperature of 240 ° C., electrical continuity was poor. As a result of cross-sectional observation of the connection portion, many bubbles were observed between the chip and the substrate, and interface peeling was observed at a part of the connection portion having poor conduction. Moreover, when the connection part was observed with the infrared microscope, corrosion was observed in a part of the aluminum pad.
[0019]
【The invention's effect】
According to the film-like adhesive for circuit connection of the present invention, since the fluidity of the adhesive at the time of heating and pressurization is high, bubbles generated in the fillet during the bonding process are quickly eliminated, and the cured fillet No bubbles remain on the surface, and it is possible to prevent a decrease in moisture resistance and mechanical strength due to the bubbles.

Claims (4)

In the heat-adhesive adhesive that electrically connects the electrodes in the pressing direction by heating and pressing the circuit electrodes facing each other,
Contains bisphenol-type liquid epoxy resin, film forming material and latent curing agent,
Cut out to a thickness of 40 μm and 5 × 5 mm, and before bonding when heated and pressed at 180 ° C., 20 seconds, 24.5 N (2.5 kgf) between 15 × 15 mm glass substrates A film-like adhesive for circuit connection, wherein the ratio (B / A) of the area (A) to the area (B) after bonding is 3.5 to 7.0 times. The film-like adhesive for circuit connection according to claim 1, wherein the bisphenol-type liquid epoxy resin is a bisphenol A-type epoxy resin. The film-like adhesive for circuit connection according to claim 1, wherein the film forming material is a phenoxy resin. The film-like adhesive for circuit connection according to any one of claims 1 to 3 , comprising 0.2 to 15% by volume of conductive particles.