JP2894093B2 - Adhesive composition and laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition formed between electrodes of two circuit boards in a liquid crystal panel or the like and suitable for connecting both electrodes.

[0002]

2. Description of the Related Art Along with bonding two circuit boards together,
As an adhesive for obtaining electrical conduction between these electrodes, a styrene-based or polyester-based thermoplastic material, or an epoxy-based or silicone-based thermosetting material is known.
In this case, conductive particles are mixed in the adhesive, and an electrical connection is obtained in the thickness direction of the adhesive by pressure (for example, JP-A-55-104007). There is a method in which electrical connection is obtained by fine irregularities on the electrode surface by pressurization at the time (for example, JP-A-60-262430). By the way, in the connection with these adhesives, if the electrical connection is poor or the electronic components and circuits become defective after the connection, the non-defective products are connected again with the adhesive after removing the adhesive with a solvent etc. by peeling off the circuit etc. That is being done. In this case, it is important that the adhesive on the microcircuit or electrode can be quickly and easily removed using a general-purpose solvent (eg, acetone, methyl ethyl ketone, toluene, tetrahydrofuran, alcohol, etc.) without adversely affecting the peripheral portion. is there. When the adhesive is a thermosetting substance or the like, a so-called epoxy release agent composed of, for example, methylene chloride and an acid is often used as the solvent.

[0003]

SUMMARY OF THE INVENTION
That is, when heat resistance and moisture resistance are considered, a thermosetting adhesive such as an epoxy-based adhesive is effective. However, the repair method in this case generally uses a strong solvent such as an epoxy release agent. In this case, the influence of the acid or the halide on the reconnection portion causes corrosion or electric corrosion of the circuit, thereby reducing the reliability of the connection portion. On the other hand, in the case of a thermoplastic adhesive, the heat resistance is insufficient, and the reliability of the connection portion is also lowered. An object of the present invention is to provide an adhesive composition having high reliability of a connection portion and easily repairable with a general-purpose solvent.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a nitrogen-containing rubber having a glass transition temperature (Tg) of 0 ° C. or less, an OH-containing polymer having a weight average molecular weight (MW) of 10,000 or more, and a weight average molecular weight. An adhesive composition comprising a solid resin of 3000 or less, an epoxy resin and a latent curing agent as essential components, and a layer containing a nitrogen-containing rubber and a layer containing an OH-containing polymer are formed separately, and at least the layer The present invention relates to a laminated film obtained by incorporating an epoxy resin and / or a latent curing agent into any one of them. The nitrogen-containing rubber having a Tg of 0 ° C. or lower used in the present invention is typically a rubber having a nitrile as a nitrogen group, such as an acrylic rubber and a nitrile rubber. Tg affects the tack of the composition before curing, and a lower Tg facilitates obtaining a desired tack over a wide range, and a temperature of -10 ° C or lower is more preferable. An appropriate tack of the composition is preferred because the alignment at the time of circuit connection is easy and the workability is improved.
The molecular weight of these is preferably 100,000 or more, more preferably 300,000 to 1.2 million. If the molecular weight is small, the cohesive strength of the adhesive system is reduced, and it is difficult to obtain high adhesive strength. If it is too large, the compatibility with other components is reduced, and it becomes difficult to handle. The molecular weight referred to in the present invention is a weight average molecular weight (converted into styrene by GPC). When these nitrogen-containing rubbers contain a polar group such as a hydroxyl group or a carboxyl group, the compatibility with the epoxy resin is improved, and a film having a uniform appearance and properties can be obtained. It is preferable from the viewpoint of obtaining time curing. Carboxyl group-containing substances are particularly preferred from the viewpoint of improving moisture resistance. The proportion of the nitrogen-containing rubber in the composition is 2% or more, preferably 3 to 30%, more preferably 5 to 20%.

The OH group-containing polymer will be described. These polymers include polymers such as polyvinyl acetal, phenoxy, polyethylene terephthalate, polyurethane, and styrene, vinyl chloride, olefin, ethylene-vinyl acetate, ethylene ionomer, and polyamide. The reason why the molecular weight is 10,000 or more is that the larger the molecular weight, the more easily the film formability can be obtained, and the melt viscosity which affects the fluidity at the time of connection can be set in a wide range. 10,000 or less is more preferable. The reason why the molecular weight is preferably not more than 80,000 is to obtain compatibility with other resins. These resins have hydroxyl groups (OH
Group) or a carboxyl group (COOH group) to improve the compatibility with the epoxy resin to obtain a film with uniform appearance and properties, and to shorten the curing time by accelerating the reaction during curing. It is also preferable from the viewpoint of obtaining. An OH group-containing polymer is particularly preferred from the viewpoint of obtaining a short curing time.

[0006] Examples of the solid resin having a MW of 3000 or less include natural resin such as rosin and terpene, aliphatic and alicyclic,
There are aromatic resins, polymer resins such as coumarone-indene and styrene, and condensation resins such as phenol and xylene, and modified products and derivatives thereof. These can be used alone or in combination of two or more. These are preferably solids having a softening point of 40 ° C. or higher from the viewpoint of increasing the cohesive force of the adhesive system. These solid resins are effective in imparting tack to the composition, and also have an effect of improving the adhesive force by improving the wettability to the bonding surface. If the MW is 3,000 or more, the compatibility in the composition is reduced, and the repairability by the solvent is reduced. Therefore, the MW is preferably 2,000 or less. When these solid resins have a polar group such as an OH group or a COOH group,
It is more preferable because the adhesiveness is improved.

The epoxy resin used in the present invention is, for example, a bisphenol type epoxy resin derived from epichlorohydrin and bisphenol A, F, D, etc., and an epoxy novolak resin derived from epichlorohydrin and phenol novolak or cresol novolak. In addition, various epoxy compounds having two or more oxirane groups in one molecule such as glycidylamine, glycidyl ester, alicyclic and heterocyclic can be applied. These can be used alone or in combination of two or more. These epoxy resins contain impurity ions (Na ⁺ , C
l ^- etc.) and the like hydrolyzable chlorine using a high purity product was reduced to 300ppm or less preferred in order to prevent electron migration.

[0008] Among the above epoxy resins, bisphenol type epoxy resins are preferred because grades having different molecular weights are widely available and adhesiveness and reactivity can be arbitrarily set. Among them, bisphenol F-type epoxy resin is particularly preferable because it has a particularly low viscosity, so that fluidity can be set in a wide range in combination with other high molecular weight substances, and that it is liquid and easy to obtain adhesiveness, and is excellent in repairability. . Further, a so-called polyfunctional epoxy resin having three or more oxirane groups in one molecule is also preferable because the crosslink density of the composition is improved and the heat resistance is improved. The occupying ratio can be used as 30% or less.

As the latent curing agent, imidazoles,
There are hydrazide type, boron trifluoride-amine complex, amine imide, polyamine salt, dicyandiamide and the like, and modified products thereof, and these can be used alone or as a mixture of two or more kinds. These are so-called ionic polymerizable catalyst-type curing agents such as anionic or cationic polymerizable types, and are preferable because they can easily obtain rapid curability and require little consideration of chemical equivalents. Other curing agents include
It is also possible to use amines, mercaptans, phenols, acid anhydrides and the like, or to use them in combination with the above-mentioned catalytic curing agent.

In a preferred embodiment of the present invention, which is required to have both contradictory characteristics such as long-term storage property and fast curing property, high molecular substances such as polyurethane and polyester, and Ni, Cu It is preferable to use a microcapsule type coated with a metal thin film such as that described above and an inorganic substance such as calcium silicate. When using the capsule-type curing agent, it should be noted that the capsule particle size is made smaller than the thickness of the film adhesive, for example, in order to prevent capsule breakage during storage, and to make the material of the capsule coating layer a composition. That is, it should be resistant to solvents and solvents.

The activation temperature of the curing agent of the present invention is 50 to 200.
C is preferable, and 70 to 150 C is more preferable. The activation temperature indicates a heat generation peak temperature when a mixture of an epoxy resin and a curing agent is used as a sample and the temperature is raised from room temperature at 10 ° C./min using DSC (differential scanning calorimeter).

The total proportion of the rubber containing a nitrogen group, the polymer containing an OH group and the solid resin having a MW of 3000 or less in the composition is about 10 to 60%, preferably 15 to 55%. If the amount is small, the repairability by the solvent is insufficient, and if it is large, the reliability of the connection portion is insufficient. In the adhesive composition obtained above, for example, a filler, a softener, an accelerator, an antioxidant, a coloring agent, a flame retardant, a thixotropic agent, a coupling agent and a phenol may be used as ordinary additives. A curing agent such as a resin, a melamine resin, or an isocyanate may be contained. Among these, fillers such as conductive particles and silica, and coupling agents of various systems such as silane, titanium, chromium, zirconium, and aluminum are particularly useful.

As the conductive particles, Au, Ag, Ni, C
u, metal particles such as solder, carbon, and the like, and those obtained by forming the above-described conductive layer on these, non-conductive glass, ceramic, plastic, or the like by coating or the like. Furthermore, the connection circuit also includes insulating coating particles obtained by coating the above-described conductive particles with an insulating layer, or a combination of conductive particles and insulating coating particles, and a combination of conductive particles and insulating particles such as non-conductive plastic particles. This is extremely useful as a means for increasing the definition of the image. The above-mentioned various particles can be used alone or in combination of two or more kinds according to various purposes. In the case of using plastic as a nucleus or hot-melt metal particles, they are deformable by heating and pressing, so that the contact area with the electrode at the time of connection increases and reliability is improved, which is preferable. 0 for conductive particles
Depending on the application, it is used in a wide range of up to 30% by volume. As the coupling agent, an amino group, an epoxy group, or a compound is particularly preferable from the viewpoint of improving the adhesiveness.

The adhesive composition of the present invention is particularly useful as a one-part adhesive, especially as a film adhesive. In this case, for example, the adhesive composition obtained above is liquefied as a solvent or a dispersion in the case of an emulsion, and is formed on a peelable substrate such as release paper, or the compounding solution is applied to a substrate such as a nonwoven fabric. Impregnated to form on a releasable substrate,
What is necessary is just to dry below the activation temperature of a hardening | curing agent, and to remove a solvent or a dispersion liquid. The boiling point of the solvent may be 150 ° C. or less. When the boiling point exceeds 150 ° C., a high temperature is required for drying, and since the temperature is close to the activation temperature of the latent curing agent, the potential is reduced. At a low temperature, the workability during drying is reduced. For this reason, the boiling point is preferably from 60 to 150C, more preferably from 70 to 130C.

Using the adhesive composition obtained in the present invention, a layer containing a rubber containing nitrogen groups and a layer containing a polymer containing OH groups are separately formed, and an epoxy resin and / or a latent cured It is also possible to form a laminated film obtained by incorporating the agent. Since the nitrogen-containing rubber and the OH-containing polymer are each of high molecular weight, the epoxy resin and / or
Alternatively, the film-forming properties are also excellent by containing a latent curing agent and other compounding agents.

The connection of circuits and electrodes using the adhesive composition obtained in the present invention will be described. In this method, an adhesive composition is formed between opposing electrodes on a substrate, and the electrodes are connected by heating and pressing to obtain contact between the electrodes and adhesion between the substrates. Substrates for forming electrodes include semiconductors, glass,
Inorganic substances such as ceramics, organic substances such as polyimide and polycarbonate, and combinations of these composites such as glass / epoxy can be applied. In the case of a laminated film,
At the time of bonding, the material of the bonding surface is determined in consideration of adhesiveness and repairability.

[0017]

According to the present invention, a nitrogen-containing rubber having a Tg of 0 ° C. or less, an OH-containing polymer having a MW of 10,000 or more, and a MW300
By using an adhesive composition essentially including a solid resin of 0 or less, an epoxy resin and a latent curing agent, the connection portion has high reliability and can be easily repaired with a general-purpose solvent.
The reason is that a nitrogen-containing rubber having a Tg of 0 ° C. or less has flexibility and adhesiveness, an OH-containing polymer having a MW of 10,000 or more has adhesiveness, a solid resin having a MW of 3000 or less is soluble in a solvent, epoxy resin and latent curing. Improvement of heat resistance after curing by the agent,
It is considered that the overall balance can be obtained by separating the functions from the storage ability by the latent curing agent and the functions thereof.

On the other hand, when the cured epoxy resin is the sea,
Nitrogen-containing rubber and OH-containing polymer with high molecular weight and low crosslink density are adsorbed and formed at high concentration on the surface of circuits composed of metal or metal oxide by their polar groups, and exist in a gradient direction in the thickness direction It is thought to be. Therefore, the bonding interface is low in the degree of cross-linking and contains nitrogen-containing rubber and / or OH.
Because it is a high-concentration layer of a group-containing polymer, it swells or dissolves easily with a general-purpose solvent together with the action of a relatively low-molecular-weight solid resin, or this part triggers the swelling or dissolution of a sea-like cured product It can be repaired. In order to more easily obtain the function and effect existing in the thickness direction, a layer containing a rubber containing a nitrogen group and a layer containing a polymer containing an OH group are formed separately, and an epoxy resin is formed on any of the layers. And / or a laminated film comprising a latent curing agent. In this case, since a layer easily swelling or dissolving with the general-purpose solvent exists on the circuit surface at a high concentration from the time of connection, repair can be performed more easily. Furthermore, according to this laminated film, the epoxy resin and the latent curing agent are separately formed to further improve the preservability, or the fluidity changes between the layer containing the nitrogen-containing rubber and the layer containing the OH-containing polymer. By doing so, bubbles generated at the time of connection can also be suppressed.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. Examples 1 to 6 and Comparative Examples 1 to 4 (1) Nitrogen group-containing rubber 25 parts by weight of butyl acrylate, ethyl acrylate 6
A monomer having 5 parts by weight, 10 parts by weight of acrylonitrile as a main monomer component, 1.5 parts by weight of acrylic acid, and 1 part by weight of hydroxylethyl methacrylate as a functional group component is polymerized by pearl polymerization to obtain an acrylic copolymer. (Abbreviated as acrylic). This copolymer was dissolved in toluene to form a solution having a solid content of 10%. The tan δ peak Tg of the copolymer measured by viscoelasticity was −20 ° C., and the MW was 400,000 (GP
(Styrene conversion value by method C). On the other hand, carboxyl-modified nitrile rubber (Tg-48 ° C, MW 100,000, C
NBR) was dissolved in toluene to obtain a solution having a solid content of 10%. (2) Preparation of composition Byron 103 (thermoplastic polyester resin, molecular weight 2
0000, containing hydroxyl group, trade name, 1
03) in a mixed solvent of toluene / dioxane = 50/50 (weight ratio) to obtain a solution having a solid content of 50%.
Epicoat YL-983U (bisphenol F type high purity liquid epoxy resin, hydrolyzable chloride ion 110pp
m, a trade name of 983U manufactured by Yuka Shell Epoxy Co., Ltd.) and YS Polyster S145 (terpene phenol resin, softening point 145 ° C., MW1100, trade name of Yashara Chemical Co., Ltd., abbreviated as S145) are each dissolved in toluene. A solution having a solid content of 50% was obtained. These and the nitrogen-containing rubber solution were mixed so as to have a solid content ratio of the combination shown in Table 1. Next, as a latent curing agent, Novacure 3742 (an imidazole-modified nucleus as a nucleus and an average particle diameter of 2 covered with polyurethane) was used.
A microcapsule type curing agent having a thickness of μm was dispersed in a bisphenol A type liquid epoxy resin, and an active temperature of 124 ° C., a trade name of Asahi Chemical Industry Co., Ltd .; Solid content of the above mixture 10
With respect to 0 parts by weight, 0.5 parts by weight of an isocyanate silane coupling agent and 2 parts by volume of conductive particles (average particle size of 5 parts by weight)
a styrene-divinylbenzene copolymer resin sphere having a thin metal layer on the surface of the sphere, which is abbreviated as plastic), stirred and applied on a polytetrafluoroethylene film (separator) using a roll coater, and then at 100 ° C. for 10 minutes. By drying, a film having a thickness of the adhesive layer of 20 μm was obtained. (3) Evaluation Using this film-like material, a flexible circuit board (FPC) having a thin layer of tin on a copper circuit having a line width of 40 μm, a pitch of 80 μm, and a thickness of 20 μm, and a thin layer of indium oxide (ITO) on the entire surface After positioning the circuit with a glass plate having a thickness of 1.1 mm and having a thickness of 170 ° C.-30 kg / mm ²
Connection was made with a width of 2 mm for -20 seconds. At this time, after adhering the film material on FPC in advance, 70 ° C-5kg
/ Mm ² -5 seconds, and then the separator was peeled off and connected to ITO. Table 1 shows the results. In Table 1, the repairability was determined by peeling the FPC of the connection portion from the ITO and leaving a fixed area (20 × 2 mm) on the ITO.
Is the time required to wipe off the adhesive with a cotton swab soaked in acetone. The reliability is 85 ° C and 85% RH-50.
0h, which is the connection resistance value of the adjacent circuit of the FPC.
It was indicated by x + 3σ of 00 points. From Table 1, Examples 1 to 6 all achieved both good repairability and reliability. On the other hand, Comparative Example 1 does not have a nitrogen-containing rubber, Comparative Examples 2 and 4 do not have an OH-containing polymer, and Comparative Example 3 does not have a solid resin. Inferior.

[0020]

[Table 1]

Examples 7 to 10 The same as Example 3, but the type of the polymer material having an OH group-containing MW of 10,000 or more was changed as shown in Table 1. The materials used here were Paraprene P25M (polyurethane resin, trade name, manufactured by Nippon Elastran Co., Ltd., abbreviated as 25M), butyral 3000K (polyvinyl acetal resin, trade name, manufactured by Denki Kagaku Kogyo Co., Ltd., abbreviated as 3000), PKHA
(Phenoxy resin, trade name, manufactured by Union Carbide Co., Ltd.) and CM8000 (soluble nylon resin, trade name, manufactured by Toray Industries, Inc., abbreviated to 8000). Table 1 shows the evaluation results in the same manner as in Examples 1 to 6. In all of Examples 7 to 10, good repairability and reliability were both obtained.

Example 11 Using the material of Example 2, a layer containing a nitrogen-containing rubber and O
A layer containing an H-group-containing polymer was formed separately. Acrylic and each solution of S145 and 3742 are solid content 10/10/3
It was mixed so as to be 0. This mixture was applied on a separator using a roll coater, and then dried at 100 ° C. for 10 minutes to obtain a film A having an adhesive layer thickness of 10 μm. On the other hand, 103 and 983 U were mixed so as to have a solid content ratio of 30/20, and further, 0.5 parts by weight of an epoxy silane coupling agent and 2 parts by volume of conductive particles (plastic) were added and stirred. A film B having a thickness of 10 μm was obtained. The A and B films were laminated by a pressure roll such that the adhesive surfaces overlapped. At this time, acrylic and S145
And 3742, the composition could be easily laminated at room temperature. The separator of the film-shaped material B was peeled off and connected to the FPC, and then the separator of the film-shaped material A was peeled off and the circuit was positioned and then connected to ITO. Table 1 shows the evaluation results in the same manner as in Examples 1 to 6. This embodiment also achieved both good repairability and reliability. In this example, the solvent repairability of the ITO circuit surface was particularly excellent.

Embodiments 12 to 15 Same as embodiment 11 except that the embodiment 7 is replaced with the embodiment 7
An OH group-containing polymer material of 10 to 10 was used. In each example, both good repairability and good reliability were obtained.

Examples 16 to 17 The same formulation as in Example 3 (Example 16) and a formulation in which conductive particles were removed from the formulation (Example 17) were used. After applying these compounds on a separator using a roll coater, the solvent was removed by drying at 100 ° C. for 10 minutes to obtain a film having a thickness of an adhesive layer of 20 μm. On the other hand, a semiconductor chip (3 × 10 mm, height 0.5 m) is placed on a glass plate.
m, a protruding gold electrode having a size of 50 μm square and a height of 20 μm called a bump is formed around four sides of the main surface.) A wiring board on which an ITO circuit having connection terminals corresponding to the bump arrangement was prepared. The film was placed between the bump surface of the semiconductor chip and the circuit of the wiring board. At this time, each film had an adhesive property at room temperature and could be easily temporarily connected to the bump surface. Thereafter, the severator is peeled off, the glass circuit and the bump are aligned, and then 170 ° C.-30 g / bump.
The connection was made by heating and pressing for 20 seconds.

In the above-mentioned connection product, there was no air bubble in the connection portion. When the continuity of the connected products was checked, all the connections were good and there was no short circuit between the bumps. PCT (pressure cooker test)-121 ° C-
After 100 hours, the results were good in each case. When the cross section of the connection portion was observed with a scanning electron microscope, in Example 16, some of the bumps were deformed and flatness was obtained in Example 17 so that the plastic particles were crushed in the pressing direction. I was in contact. From these facts, both examples were able to cope with variations in bump height. The connection product of each example was heated to 150 ° C. higher than the Tg of the adhesive cured product of 125 ° C. to reduce the cohesive force of the cured product, peel the semiconductor chip from the wiring board, dipped in acetone, and washed 5 minutes later. However, the adhesive could be removed. Separately, the connection products of the respective examples were methyl ethyl ketone / tetrahydrofuran / toluene = 35/35/30 (weight ratio) and methyl ethyl ketone / dimethylformamide / ligroin = 50.
3/30/20 (weight ratio)
Observation after 0 minutes revealed that in both the immersed products, the semiconductor chip was separated from the wiring board and the remaining adhesive was swollen. When the semiconductor chip and the wiring board were washed with a cloth impregnated with methanol, the adhesive was easily removed.

[0026]

As described above in detail, according to the present invention, it is possible to provide an adhesive composition having a high reliability of a connection portion and easily repairable with a general-purpose solvent.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor, Kyohisa Ota, 1500, Oji, Oji, Shimodate, Ibaraki Prefecture Hitachi Chemical Co., Ltd., Shimodate Research Institute (72) Inventor, Yutaka Yamaguchi 1500, Oji, Oji, Shimodate, Ibaraki, Hitachi, Ltd. (56) References JP-A-6-212139 (JP, A) JP-A-5-156229 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09J 163/00-163/10 C09J 7/00 B32B 27/00 H01B 1/20

Claims (3)

(57) [Claims] 1. A general-purpose solvent comprising the following components (a) to (e):
An adhesive composition for circuit connection that can be repaired more . (a) a nitrogen-containing rubber having a glass transition temperature of 0 ° C. or less, (b) an OH-containing polymer having a weight-average molecular weight of 10,000 or more, (c) a solid resin having a weight-average molecular weight of 3000 or less, (d) an epoxy resin And (e) a latent curing agent 2. The adhesive composition according to claim 1, wherein the proportion of (a) to (c) in the adhesive composition is 10 to 60%. 3. A layer containing a nitrogen-containing rubber having a glass transition temperature of 0 ° C. or less and a layer containing an OH-containing polymer having a weight average molecular weight of 10,000 or more are formed separately. An adhesive film for circuit connection which can be repaired with a general-purpose solvent obtained by integrating a solid resin having a weight average molecular weight of 3000 or less , an epoxy resin and / or a latent curing agent.