JP2004197109A - Composition for removing adhesive of circuit joint and method for removing using the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for removing, efficiently removing an adhesive on a part requiring repair and excellent in connection reliability, and to provide a method for removing. <P>SOLUTION: The composition for removing comprises 100 pts. wt. mixed solvent of oxygen-containing organic solvent with a nitrogen-containing organic solvent and having ≥110°C boiling point and 0.5-50 pts. wt. fine particles of a porous material insoluble in the above-mentioned solvents, and the method comprises wiping off and cleaning up the unneeded part with the composition for removing. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a stripping composition suitable for repairing a connection portion such as a circuit or an electrode with an adhesive, and a stripping method using the same.

  As electronic components become smaller and thinner, circuits, electrodes, and the like used for these components are becoming higher in density and higher in definition. For connection of these fine circuits and the like, a method using an adhesive has recently been frequently used. In this case, a conductive particle is blended in an adhesive and an electrical connection is made in the thickness direction of the adhesive by pressing (for example, Patent Document 1), and an electrode is formed by pressing during connection without using conductive particles. There is a device that obtains electrical connection by fine irregularities on the surface (for example, Patent Document 2).

  In the connection with these adhesives, if the electrical connection is poor or the electronic components and circuits become defective after the connection, peel off between the connection parts and remove the remaining adhesive with a solvent or a peeling liquid etc. Then, the non-defective product is connected again with the adhesive. At this time, in the case where a large number of other electronic components such as an IC chip are connected to one electronic component having a large number of connection circuits such as a liquid crystal display panel, in the case of the method of removing the adhesive, the peripheral portion is not used. There is a problem in that it affects other connection parts, resulting in poor connection and reduced reliability.

  In recent years, adhesives used in such applications are often used in the form of heat or ultraviolet rays for curing because of their excellent connection reliability. Had been used while having the problem of decreasing. As a countermeasure for these problems, the present inventors have previously proposed an attempt to include a stripping liquid in a porous sheet having a predetermined shape substantially equal to the area of the adhesive requiring repair, and to peel the porous sheet into contact with the adhesive requiring repair. (Patent Document 3).

JP-A-55-104007 JP-A-60-262430 JP-A-03-283284

  The method disclosed in Patent Document 3 (Japanese Patent Application Laid-Open No. 03-283284) is an extremely effective peeling method for a limited area. However, since a porous sheet having a predetermined shape is formed only in a portion requiring repair, a sheet is formed. The workability is lacking due to the necessity of accurate cutting and setting of the sheet and the impregnation of the stripping solution. In addition, when an acid or a halogen-based solvent is contained in the stripping solution, electrolytic corrosion is easily generated, and connection reliability is insufficient. In addition, when connecting a circuit on a glass epoxy substrate, if the surface of the adhesive that needs to be peeled is near an adhesive material similar to this, the underlying substrate depends on the level of the peeling liquid. However, there is a disadvantage that the adhesive of the present invention and the adhesive of the circuit and the substrate are also deteriorated.

  The present invention has been made in order to solve the above-mentioned disadvantages, and proposes a peeling composition and a peeling method which can efficiently peel off an adhesive only in a portion requiring repair and have excellent connection reliability. is there.

  The present invention contains 0.5 to 50 parts by weight of a porous fine powder insoluble in a solvent based on 100 parts by weight of a mixed solvent of an oxygen-containing organic solvent having a boiling point of 110 ° C. or higher and a nitrogen-containing organic solvent. The present invention relates to a method for peeling off an adhesive at a circuit connecting portion, and a method for bringing the composition into contact with an adhesive portion which needs to be peeled off, removing the contact after a temporary contact, and cleaning.

  ADVANTAGE OF THE INVENTION According to this invention, since the adhesive agent of a required part can be peeled efficiently, it is excellent in workability. Further, the liquid material of the release agent is only a non-halogen organic solvent, and the connection reliability can be maintained.

  The organic solvent used in the present invention will be described in detail. The organic solvent has a property of decomposing, swelling, and dissolving the adhesive, and particularly, a solvent which is easy to decompose, swell, and dissolve the cured adhesive is preferable. Therefore, a mixed solvent of an oxygen-containing organic solvent and a nitrogen-containing organic solvent having a boiling point (760 mmHg) of 110 ° C. or higher is used as an essential solvent in the present invention. Such a solvent is disclosed in, for example, Kodansha Co., Ltd., Solvent Handbook, 7th edition, pages 632 to 756, and these can be applied. The present invention requires the use of a mixed solvent of an oxygen-containing organic solvent and a nitrogen-containing organic solvent having a boiling point (760 mmHg) of 110 ° C. or higher as described above. You may mix | blend a solvent suitably.

  Examples of these solvents include diacetone alcohol (boiling point: 168 ° C.), acetonylacetone (191 ° C.), mesityl oxide (129 ° C.), diisobutyl ketone (168 ° C.), and holon ( 198 ° C), isophorone (215 ° C), 2-hexanone (127 ° C), methyl isobutyl ketone (116 ° C), 2-heptanone (150 ° C), 4-heptanone (144 ° C), cyclohexanone (155 ° C), methylcyclohexanone (170 ° C.), acetophenone (202 ° C.) and the like. Among these, those having two or more carbonyl groups in one molecule are particularly preferable since the cured adhesive is easily decomposed or swelled. Further, as the oxygen-containing organic solvent, in addition to the above ketones, esters, ethers, and phenols are applicable. Examples of the esters include butyl acetate (boiling point: 126 ° C.), pentyl formate (130 ° C.), pentyl acetate (150 ° C.), and benzyl acetate (213 ° C.). As ethers, dibutyl ether (142 ° C.), dihexyl ether (226 ° C.), anisole (153 ° C.), phenetosol (172 ° C.), methoxytoluene (172 ° C.), benzyl ethyl ether (189 ° C.), trioxane (114 ° C.) ), Diethylene glycol diethyl ether (188 ° C.) and the like. Examples of the nitrogen-containing organic solvent include formamide (boiling point: 210 ° C.), N, N-dimethylformamide (153 ° C.), N, N-dimethylacetamide (166 ° C.), N, N-diethylformamide (177 ° C.), acetamide (221) C), N-methylformamide (180C), N-methylpyrrolidone (202C), nitropropane (131C), nitrobenzene (211C), 2-pyrrolidone (245C) and the like. These can be arbitrarily mixed and used. From the viewpoint of suppressing volatility, these boiling points can be applied at 110 ° C. or higher, preferably at 120 ° C. or higher, and more preferably at 140 ° C. or higher.

It is necessary that the solvent in the stripping solution be a non-halogen organic solvent containing no acid or halogen solvent, in order to maintain connection reliability. The lower the viscosity of the solvent is, the better the permeability to the adhesive to be peeled is. Further, the SP value is preferably 8 or more, more preferably 10 or more, since the erosion action of the adhesive is large. The porous fine powder used in the present invention has a large number of small voids inside or on the surface, and is required to be insoluble in the solvent of the stripping composition. In order to form the peeling composition only on the portion requiring repair, the pore size of the void is preferably 100 μm or less, more preferably 40 μm or less, from the viewpoint of the fineness of the applied circuits. In the present invention, a BET specific surface area (ASTMD-3037-73) of 1 m ² / g or more is preferably used as an index indicating the degree of voids, and more preferably 10 m ² / g or more.

  In addition, a porous body having an oil absorption (JIS K5101) of 20 or more can also be preferably used. When the porous fine powder used in the present invention is soluble in a solvent, the thixotropic properties of the release composition and the retention of the solvent decrease, which is not preferable. However, these properties are not significantly reduced, and there is a practical problem. If not, the degree of swelling may be small. Examples of these porous fine powders include carbonates such as calcium carbonate and magnesium, hydroxides such as aluminum hydroxide and magnesium, oxides such as zinc oxide and magnesium, and silicic acids and silicic acids such as silica, smectite, and talc. Salts and polymer particles such as styrene and epoxy resin. In the case of polymer particles, a crosslinked body is preferable for preventing deterioration by a solvent. Also, conductive materials such as carbon are preferable because they have an action of removing static electricity generated by friction in the cleaning step. These particles are preferably in the form of fine particles since thixotropicity can be obtained even with a small amount of addition, and the particle size is 10 μm or less, more preferably 1 μm or less. Further, those obtained by pulverizing a porous sheet of a crosslinked polymer or a water-absorbing resin by pulverization or the like can also be used. In this case, since the size of the fine powder can be applied to a relatively large size of several mm or less, preferably several hundred μm or less, the fine powder can be easily dispersed in the peeling composition, and the amount of the solvent retained is large. It is possible and preferable. It is also possible to use a mixture of the finely divided material and the finely divided material.

  The above composition is adjusted to a liquid state to obtain the release composition according to the present invention. The reason why the liquid is used is that it can be easily formed only in a portion requiring repair. At this time, the viscosity (JIS K6833) of the composition is preferably 100 cps or more, and more preferably 800 cps or more. As the upper limit of the viscosity, a wide range up to a paste of about 100,000 cps can be applied. The thixotropic index according to the same method is preferably 1.2 or more, more preferably 1.5 or more. When the viscosity is low, the permeability to the adhesive is excellent, and when the thixotropic index is large, the precision in forming fine details is improved. For these reasons, the amount of the porous fine powder to be added is preferably 0.5 to 50 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the solvent. In the peeling composition, for example, a polymer as a thickener soluble in the solvent used, a surfactant that enhances the permeability of the solvent to the adhesive to be peeled, a coloring to clearly indicate a formation area Materials can be used as needed.

  A stripping method using the above-described stripping composition will be described. First, the mutual joints of the connection portions requiring repair are peeled off as necessary, and the adhesive surface requiring peeling is exposed. At this time, for example, when the heating is performed while the temperature is higher than the glass transition point of the adhesive, the peeling is easy. This step can be omitted when the peeling composition can easily penetrate into the joint, such as when the repair area is very small. Next, a peeling composition is formed on the exposed surface of the adhesive which needs to be peeled off, and is brought into contact with the adhesive temporarily. As the forming means, since the peeling composition is in a liquid state, for example, a brush, a dispenser, a silk screen or the like can be appropriately selected. At this time, a portion which is not removed may be protected by a masking tape or the like in order to prevent a bad influence on a peripheral portion. The contact time is determined by the time for dissolving or dissolving the adhesive. At this time, if the heating is performed to such an extent that volatilization of the high boiling point solvent can be suppressed, the adhesive can be more easily decomposed or dissolved, which is effective in shortening the working time. Thereafter, the surface on which the release composition is formed is wiped off with a cloth, paper, a cotton swab, or the like, or is wiped with a cloth impregnated with a solvent such as acetone or alcohol to remove the adhesive and clean. I do.

  The adhesive to which the present invention is applied preferably has a curing agent mainly composed of a catalyst-curing type epoxy resin, for example. That is, since the adhesive for circuit connection needs to be cured in a short time, a catalyst-curable type for initiating ring-opening polymerization is used. On the other hand, as a substrate or an adhesive between the substrate and the circuit, a polyaddition type is frequently used, and since the structures of these cured products are different, a difference occurs in solvent resistance. In general, the polyaddition type, which is not sufficiently formed into a network, has insufficient mechanical properties when compared with the catalyst-curing type, and therefore has a sufficient curing reaction to produce a product and has high solvent resistance. Examples of the catalyst-curable type include tertiary amines such as benzyldimethylamine, imidazoles such as 2-methylimidazole, and cationic catalysts such as Lewis acids and onium salts. Examples of the polyaddition type include polyamine, phenol novolak and resole, polymercaptan and acid anhydride.

  According to the present invention, a peeling composition is formed on the adhesive portion that needs to be peeled off, and is temporarily contacted. At this time, since the porous fine powder is contained, the peeling composition has a thixotropic property, and is relatively liquid and relatively low when the peeling composition is formed on the adhesive portion requiring peeling. Although it is easy to form due to its viscosity, it acts as a thickener when left standing after formation to prevent it from flowing out of the required parts and facilitate formation of only those parts requiring repair. In addition, the solvent filled in the voids of the porous fine powder exudes to the interface with the adhesive during the contact process and constantly wets the adhesive that needs to be peeled off, and can be in contact with the adhesive for an arbitrary time. At this time, since the composition contains a compound having a high boiling point, it is difficult to volatilize. Moreover, since the peeling composition contains an organic solvent having a strong property of decomposing, dissolving, and swelling the adhesive, the composition can be in a peelable state. Since the solvent in the stripping composition is only an organic solvent, it is possible to maintain the connection reliability of the repaired portion and / or its peripheral portion, and the stripping solution contains no acid or halogen-based solvent. The effect is remarkable.

Hereinafter, the present invention will be described specifically with reference to examples.
Reference Examples 1-3
(1) Preparation of stripping composition Mixing ratio of Aerosil 130 (high-purity silica, particle size of about 16 μm, BET specific surface area of 130 m ² / g, abbreviated as 130) to acetonylacetone (1 part by weight ratio; reference) Example 1, 5 parts Reference Example 2, 10 parts Reference Example 3 was changed and kneaded and added in a mortar. The viscosity (JIS K6833) and thixotropic index (TI) of Reference Examples 1 to 3 were 250 cps, 1.3 (Reference Example 1), 800 cps, 2.0 (Reference Example 2), 1500 cps, 3.5 (Reference Example). 1).
(2) Connection body A glass substrate having an ITO circuit terminal and three FPC circuit boards having a connection width of 10 mm (both having a circuit width of 50 μm and a circuit interval of 50 μm) having an interval of 0.5 mm and an anisotropic conductive adhesive film (Imidazo) Conductivity at 170 ° C.-20 kg / cm ² -20 seconds using an epoxy adhesive containing a catalyst-type curing agent containing a catalyst as a main component and a trade name of Anisorm AC-7073, manufactured by Hitachi Chemical Co., Ltd., having a thickness of 25 μm. Connected. It was confirmed that the adhesive was cured under these connection conditions and sufficient connection reliability was obtained.
(3) Peeling Only the FPC circuit board at the center of the connection body of the above (2) was mechanically gently peeled off. The adhesive cured by connection remained on the peeled surfaces of the glass substrate and the FPC circuit board. On the release surface, the release composition of (1) was formed to a thickness of about 2 to 3 mm using a spatula made of tetrafluoroethylene. At this time, the higher the number of Reference Examples 1 to 3, the higher the viscosity and the state was close to a paste-like state, and the formation was easy. After allowing to stand in that state for 30 minutes, the adhesive and the stripping composition were removed by rubbing with a cotton swab, and further cleaned with a cotton swab impregnated with acetone. Similarly, the FPC circuit was cleaned. In both cases, there was no permeation into other parts of the stripping composition, and only the necessary parts could be stripped.
(4) Reconnection Using the cleaned glass substrate and FPC obtained in the preceding section, reconnection was performed using AC-7073 in the same manner as described above. The difference between the connection resistance of the reconnected FPC circuit part, the connection resistance of the adjacent FPC circuit, and the connection resistance before the removal of the adhesive was within ± 0.5Ω. No increase in connection resistance was observed. In the FPC used in Reference Examples 1 to 3, an epoxy-based adhesive was also a main component (a curing agent was hexahydrophthalic anhydride / dicyandiamide-based) as an adhesive between a copper foil and a polyimide substrate. No deterioration of the agent was observed. The reason for this is that the FPC adhesive is a polyaddition type, whereas the adhesive for the anisotropic conductive adhesive film is a catalyst-curable type that initiates ring-opening polymerization, and the structure of the cured product is different, resulting in poor peelability. It is considered that there was a difference.

Comparative Example 1
Same as Reference Examples 1 to 3, but without the porous fine powder of the release composition. In this case, when the peeling composition was formed and allowed to flow, it flowed to the adjacent FPC circuit portion, and the connection resistance of the adjacent FPC increased.

Examples 1 to 5
(1) Preparation of stripping composition Acetonylacetone (AA) / N-methylpyrrolidone (NMP) / Aerosil (AE) 130 (high-purity silica, particle diameter of about 16 μm, BET specific surface area of 130 m ² / g, 130 (Abbreviation) was changed as shown in Table 1 and kneaded in a mortar. These viscosities (JIS K6833) and thixotropic index (TI) were measured in Example 1 (1000 cps, TI 2.1), Example 2 (250, 1.3), Example 3 (700, 2.1), and Example 4 (1500, 3.5) and Example 5 (500, 1.9).
(2) Connection body A glass substrate having an ITO circuit terminal and three FPC circuit boards having a connection width of 10 mm (both having a circuit width of 50 μm and a circuit interval of 50 μm) having an interval of 0.5 mm and an anisotropic conductive adhesive film (Imidazo) Conductivity at 170 ° C.-20 kg / cm ² -20 seconds using an epoxy adhesive containing a catalyst-type curing agent containing a catalyst as a main component and a trade name of Anisorm AC-7073, manufactured by Hitachi Chemical Co., Ltd., having a thickness of 25 μm. Connected. It was confirmed that the adhesive was cured under these connection conditions and sufficient connection reliability was obtained.
(3) Peeling Only the FPC circuit board at the center of the connection body of the above (2) was mechanically gently peeled off. The adhesive cured by connection remained on the peeled surfaces of the glass substrate and the FPC circuit board. On the release surface, the release composition of (1) was formed to a thickness of about 2 to 3 mm using a spatula made of tetrafluoroethylene. After allowing to stand in that state for 30 minutes, the adhesive and the stripping composition were removed by rubbing with a cotton swab, and further cleaned with a cotton swab impregnated with acetone. Similarly, the FPC circuit was cleaned. In both cases, there was no permeation into other parts of the stripping composition, and only the necessary parts could be stripped.
(4) Reconnection Using the cleaned glass substrate and FPC obtained in the preceding section, reconnection was performed using AC-7073 in the same manner as described above. The difference between the connection resistance of the reconnected FPC circuit part, the connection resistance of the adjacent FPC circuit, and the connection resistance before the removal of the adhesive was within ± 0.5Ω. No increase in connection resistance was observed. In the FPC used in Examples 1 to 5, an epoxy-based adhesive was also used as an adhesive (a curing agent was hexahydrophthalic anhydride / dicyandiamide-based) as an adhesive between a copper foil and a polyimide substrate. No deterioration of the agent was observed. The reason for this is that the FPC adhesive is a polyaddition type, whereas the adhesive for the anisotropic conductive adhesive film is a catalyst-curable type that initiates ring-opening polymerization, and the structure of the cured product is different, resulting in poor peelability. It is considered that there was a difference.

Examples 6 to 10
Same as Examples 1 to 5, except that the type and composition of the release composition were changed. That is, diacetone alcohol (DA), diisobutyl ketone (DB), formamide (HA), and smectite SAN (synthetic smectite, BET specific surface area 750 m ² / g, SAN) are new. In each of the examples, since the release composition has thixotropy, it is easy to form, and it is thickened by standing after formation to prevent it from flowing out of the required part and to form only the part that needs repair. Was easy. Also, no increase in connection resistance at the reconnection portion was observed, and good reconnection was possible.

Example 11
Using the peeling composition of Example 3, the structure of the connector was changed. That is, it has connection terminals corresponding to the bump arrangement of a semiconductor chip (3 × 10 mm, height 0.5 mm, protruding gold electrodes of 100 μm square and 20 μm height called bumps around four main surface sides). A glass epoxy substrate having a thickness of 1 mm (a circuit was made of copper foil and had a thickness of 18 μm, an adhesive was mainly composed of an epoxy resin, and a curing agent was a diaminodiphenylmethane / imidazole system) was prepared. In the same manner as in Example 1, an anisotropic conductive adhesive film (an epoxy resin containing an imidazole-based anionic polymerization catalyst curing agent as a main component, trade name: Anisolm AC-8201, manufactured by Hitachi Chemical Co., Ltd., thickness: 30 μm) was used. The conductive connection was performed at 170 ° C.-20 kg / cm ² -20 seconds. It was confirmed that the adhesive was cured under these connection conditions and sufficient connection reliability was obtained. Subsequent to the above, the connector was gently peeled off while applying a shearing force while being heated to 180 ° C. on a hot platen. A release composition was formed on the release surface in the same manner as in Example 1. After standing for 20 minutes, removal, cleaning, and reconnection were performed using tweezers made of tetrafluoroethylene. In both examples, there was no permeation into the other part of the peeling composition, and only the necessary part of the adhesive could be removed. The connection resistance after reconnection was good, and the reliability was excellent.

Example 12
Same as Example 11, but without forcibly peeling the semiconductor chip, forming a peeling composition on the adhesive protruding portion around the connection portion and peeling it after standing for 24 hours. there were. Thereafter, the same evaluation as in Example 11 was performed, but good reconnection was possible. Also in Examples 11 and 12 above, since the structures of the cured products of the anisotropic conductive adhesive film and the glass epoxy substrate were different, deterioration of the adhesive of the glass epoxy substrate was not observed by visual observation.

Claims (3)

A circuit connection comprising 0.5 to 50 parts by weight of a porous fine powder insoluble in a solvent based on 100 parts by weight of a mixed solvent of an oxygen-containing organic solvent having a boiling point of 110 ° C. or higher and a nitrogen-containing organic solvent. Part of the composition for peeling off the adhesive. A method for peeling off a circuit connecting portion, comprising: bringing the composition of claim 1 into contact with a circuit connecting portion requiring peeling, and wiping / cleaning after temporary contact. 3. The method according to claim 2, wherein the adhesive of the circuit connecting portion is mainly composed of a catalyst-curable epoxy resin.