KR20040105832A - Thermosetting Adhesive Sheet with Electroconductive and Thermoconductive Properties - Google Patents

Abstract

The present invention includes a thermosetting adhesive sheet composed of a thermosetting adhesive composition comprising an ethylene-glycidyl (meth) acrylate copolymer and a carboxyl group-containing rosin, wherein crosslinking is formed between ethylene of the copolymer by electron beam irradiation. Wherein the at least one through opening region is formed at a predetermined position and further comprises a low melting solder disposed within the through opening region (s) formed at the predetermined position (s). It relates to a thermosetting adhesive sheet having.

Description

Thermosetting Adhesive Sheet with Electroconductive and Thermoconductive Properties

In a mounted electronic component known as TAB or Tape Ball Grid Array (T-BGA), such as shown in cross-section in FIG. 1, the integrated circuit (IC) chip (A) is a TAB (metal wiring on insulating film). Connected tape) (B), and the solder ball C formed on the TAB (B) is connected to a wiring board (not shown). In order to radiate heat generated from the IC and to prevent charging, the IC chip A is attached to the heat sink E by the conductive adhesive D. In order to stabilize the TAB (B) connected to the IC chip (A) and improve the overall strength of the electronic components, a stiffener (F) is formed between the TAB (B) and the heat sink (E). Is placed through). In the case of the electronic component shown in Fig. 1, a ground conductive path is formed in order to remove noise charged to the IC chip A, which leads solder from the heat sink E to the TAB B. It is formed by attaching. Typically, conductive adhesives mixed with silver powder, such as conductive silver pastes, are typically used as conductive adhesives.

However, because the conductive adhesive includes a large amount of silver powder or other metal filler dispersed in the insulating polymer or monomer, the material cost can be high. Therefore, in the case of the TAB type shown in Fig. 1, the mounting step is complicated because it is difficult to apply to large-area adhesion, and eventually cheap solder is used to ground from the heat sink. In recent years, as the integration of IC chips has become more advanced, and powder consumption has increased, the amount of heat dissipation has also increased. Since the above-mentioned conductive adhesives, in which silver powder or the like is incorporated, generally have a thermal conductivity of 3 to 5 W / mK, they are insufficient as a suitable heat dissipation countermeasure for IC chips having a high heat dissipation amount.

Therefore, a cheaper electroconductive adhesive sheet with high thermal conductivity is desired. Japanese Patent Laid-Open No. 11-21522 relates to a thermally conductive adhesive sheet in which a plurality of row-shaped heat conductive portions and a row-shaped adhesive portion are alternately arranged on one side or both sides of a supporting substrate. The stripe thermally conductive portion is prepared by coating a thermally conductive paste (a mixture of a thermally conductive powder such as silver and a resin solution in a solvent). The annular disk integrated by stacking a plurality of adhesive sheets and thermally conductive sheets is rotated at low temperature to cut the peripheral circumference in a specific thickness in a continuous manner. Adhesive sheets are used to secure electronic components on temperature sensors.

Japanese Patent Laid-Open No. 5-259671 relates to a heat dissipation sheet in which a plurality of thermal conductive fillers are dispersed in a matrix resin. While the thermally conductive filler penetrates in the thickness direction of the heat dissipation sheet, the thermally conductive filler is oriented in the matrix resin so that both ends are exposed on the surface of the matrix resin. The matrix resin used is a silicone rubber or polyolefin-based elastomer to obtain adhesion with the article to be cooled. Conductive fillers are typically metal materials such as gold, copper or aluminum. Since the filler used is exposed on the sheet surface, adhesives with high viscosity can be difficult to use as matrix resin. Since the exposed portion of the filler is treated to prevent the formation of the resin film by a masking agent such as paraffin or styrene rubber, the resin coating can be very difficult.

Several patent documents disclose an anisotropic conductive adhesive film for electrically connecting a microelectrode or a microwiring while maintaining electrical insulation between each microelectrode or microwiring. Japanese Patent Laid-Open No. 8-306415 and Japanese Patent Laid-Open No. 3-266306 relate to an anisotropic conductive adhesive film. In the films of the above patents, a plurality of fine through holes are formed in an insulating film such as polyimide in the thickness direction thereof, and a metal material is filled in the plurality of through holes. The metal material is filled by forming riveted metal protruding ridges, thereby preventing the metal from peeling off the film. Plating, sputtering and similar methods are used to form riveted bumps. These anisotropic conductive adhesive films also provide electrical connections for microwiring and the like, and the through holes can be as small as 15 to 100 μm. Such adhesive films may have low thermal conductivity, so they may not be sufficiently suitable for heat dissipation purposes.

Japanese Patent Laid-Open No. 5-205531 relates to an anisotropic conductive film in which a metal film is filled in a hole formed in an insulating adhesive sheet. The metal film is filled by transferring the metal film formed on the transfer sheet in a transferable manner to the holes formed in the adhesive sheet. Filling requires a metal film with an area larger than the filling area. Filling is accomplished by a compression cutting system, and the metal film can be stripped off during processing or during transfer. Further, such anisotropic conductive adhesive films such as those disclosed in Japanese Patent Application Laid-Open No. Hei 8-306415 and Japanese Patent Application Laid-Open No. Hei-3-266306 serve as electrical connections for fine wiring and the like. Low thermal conductivity is not suitable for heat dissipation purposes.

Summary of the Invention

The present invention provides a thermosetting adhesive sheet having high thermal conductivity and conductivity, and which is cheaper than others.

Specifically, the present invention includes a thermosetting adhesive sheet composed of a thermosetting adhesive composition comprising an ethylene-glycidyl (meth) acrylate copolymer and a carboxyl group-containing rosin, and between electrons radiation between ethylene portions of the copolymer. The thermosetting adhesive sheet which has electroconductivity and thermal conductivity in which bridge | crosslinking is formed in is provided. At least one through opening region is formed in the adhesive sheet at a predetermined position, and a low melting point solder is disposed in the through opening region formed at the predetermined position.

The thermosetting adhesive sheet can impart high conductivity and high thermal conductivity only in the thickness direction and in a predetermined region. Metal usage can also be reduced compared to conventional conductive adhesives. Thermosetting adhesive sheets of this type are particularly useful for bonding electronic devices, such as semiconductor devices, onto heat sinks.

The present invention relates to a thermosetting adhesive sheet having conductivity and thermal conductivity. Adhesive sheets are particularly useful for bonding between electronic devices such as integrated circuit chips and heat sinks that can radiate heat.

1 is a cross-sectional view of a conventional electronic component formed by a TAB system.

2 is an exploded perspective view of one exemplary embodiment of an electronic component using a thermosetting adhesive sheet according to the present invention.

3 is a top view of the thermosetting adhesive sheet of the present invention used in the examples.

4 is a schematic diagram of an apparatus for measuring thermal conductivity.

<Thermosetting adhesive sheet>

The thermosetting adhesive sheet of the present invention uses a thermosetting adhesive sheet composed of a thermosetting adhesive composition comprising an ethylene-glycidyl (meth) acrylate copolymer and a carboxyl group-containing rosin. Electron beam radiation forms crosslinks between the ethylene units of the copolymer. The adhesive sheet has one or more through opening regions through a predetermined position or positions. The adhesive sheet further includes a low melting solder disposed within a predetermined position to impart conductivity and thermal conductivity. In the description and examples of the invention, all numbers should be considered to be modified by the term "about."

Thermosetting adhesive compositions (hereinafter also referred to simply as " adhesive compositions &quot;) are solid at ambient temperature, but at a relatively low pressure and in a short time at a predetermined temperature (eg, a temperature of 100 to 200 ° C., 0.1 to 10 kg / cm ^2). Pressure and time of 0.1 to 30 seconds). Heating (also called postcure) during or after compression bonding can result in curing (crosslinking) without moisture. Throughout this application, the term "ambient temperature" will mean approximately 25 ° C.

The thermosetting temperature is usually above 150 ° C. and the heating time is generally 1 minute or more. Since the thermosetting reaction is essentially a reaction between the epoxy group of the ethylene-glycidyl (meth) acrylate copolymer and the carboxyl group of the carboxyl group-containing rosin, almost no reaction by-products such as water are produced.

The precursor of the adhesive composition melts at a lower temperature (eg, less than 120 ° C.) than conventional hot-melt adhesives and is therefore easily hot-melt coated. In addition, because of the relatively high flowability during the hot melt process, very little solvent is needed for coating or film formation. The term “precursor” means an adhesive in a state before intermolecular crosslinking is formed by electron beam radiation.

Intermolecular crosslinking is formed between the ethylene units of the ethylene-glycidyl (meth) acrylate copolymer. The crosslinking reaction is promoted between the ethylene units when the ethylene units are radically activated by electron beam radiation.

The crosslinked structure improves the modulus during the thermo-compression bonding of the adhesive composition. This modulus of elasticity prevents the adhesive composition layer interposed between the two adherends from excessively flowing during the heat-pressing operation. In addition, this improvement in elastic modulus effectively prevents a decrease in adhesive performance that may occur if the adhesive layer thickness is not appropriate.

The modulus of elasticity of the adhesive composition may be defined by the storage modulus (G ′) at 150 ° C. However, since the curing reaction of the adhesive composition is promoted by heating, it may not exhibit a constant elastic modulus at this temperature. Therefore, the storage modulus of the adhesive composition is defined according to the following conditions. Samples were taken from the adhesive composition prior to use (prior to application on the adherend, ie before heat-compression bonding, etc.) and using a dynamic viscoelastometer, the temperature of the sample was changed from 80 ° C. to 280 ° C. at 5 ° C. / The storage modulus is measured at a shear rate of 6.28 rad / sec while raising the temperature at the rate of minutes. The numerical value of the storage modulus at 150 ° C. on the obtained chart (temperature vs. storage modulus) is defined as the “storage modulus” of the adhesive composition.

The storage modulus of the adhesive composition as defined above is generally 1 × 10 ⁴ to 1 × 10 ⁶ dynes / cm ² , particularly suitably 2 × 10 ⁴ to 3 × 10 ⁵ dynes / cm ² . If the storage modulus is too small, the effect of preventing flow during the thermo-compression bonding operation is reduced, and if the storage modulus is too large, the instantaneous adhesion (for example, 30 seconds or less) is poor during the thermo-compression bonding operation. can do. If so, the part may be peeled from the adhesive sheet while transferring the bonded part to the post-processing step.

The curing reaction between the glycidyl (meth) acrylate copolymer and the carboxyl group-containing rosin occurs gradually at the heating temperature for melt coating or compression molding. Thus, the viscosity does not significantly increase to a level where the adhesive composition precursor gels or may cause problems in a continuous process. In addition, since the curing reaction does not typically occur below 90 ° C., it is possible to increase the storage stability of the adhesive composition. On the other hand, since the hardening reaction accelerates rapidly at the temperature exceeding 150 degreeC, the thermosetting process time for postcure can be shortened.

The adhesive composition used for the present invention can be prepared by forming an adhesive composition precursor into a sheet and forming a crosslinked structure between copolymer molecules by irradiating the molded sheet with an electron beam.

When the adhesive composition is heated at a predetermined temperature, the ethylene-glycidyl (meth) acrylate copolymer undergoes a curing reaction with the carboxyl group-containing rosin, thereby increasing the cohesion of the cured product. High cohesion is advantageous for improving adhesive performance such as peel adhesion.

In addition, the ethylene-glycidyl (meth) acrylate copolymer has a function of facilitating melt coating when the adhesive composition precursor is melted at a relatively low temperature. In addition, satisfactory heat adhesion is imparted to the adhesive composition. "Heat adhesive" means adhesion to the adherend in the cooling and solidifying step after melting the adhesive composition and adhering to the adherend.

The ethylene-glycidyl (meth) acrylate copolymer can be formed, for example, by polymerizing a monomer mixture comprising a glycidyl (meth) acrylate monomer and an ethylene monomer as starting monomers. In addition to the monomers described above, third monomers such as propylene, alkyl (meth) acrylates or vinyl acetate can also be used as long as the effects of the present invention are not impaired. In this case, the minimum carbon number of the alkyl group of the alkyl (meth) acrylate will be 1, and the maximum carbon number will be 8. Suitable examples of ethylene-glycidyl (meth) acrylate copolymers include dipolymers of glycidyl (meth) acrylate and ethylene, terpolymers of glycidyl (meth) acrylate, vinyl acetate and ethylene, and Terpolymers of glycidyl (meth) acrylate, ethylene and alkyl (meth) acrylate.

The ethylene-glycidyl (meth) acrylate copolymer has a proportion of at least 50% by weight, particularly suitably at least 75% by weight, of the repeating units polymerized from the monomer mixture of glycidyl (meth) acrylate and ethylene relative to the total polymer. It includes. The polymerization ratio of glycidyl (meth) acrylate (G) and ethylene (E) in the repeating unit is preferably 50:50 to 1:99, particularly suitably 20:80 to 5:95. If the ethylene content is too low, compatibility with rosin may be reduced to such an extent that a uniform composition cannot be achieved and electron beam crosslinking may be difficult. On the contrary, when the ethylene content is too high, the adhesion performance may decrease. The ethylene-glycidyl (meth) acrylate copolymer can be used as a single species or as a mixture of two or more species.

The melt flow index (hereinafter abbreviated as "MFR") of the ethylene-glycidyl (meth) acrylate copolymer is generally at least 1 g / 10 minutes as measured at 190 ° C. A melt flow index of at least 1 g / 10 minutes will enable thermal adhesion of the adhesive composition. In order to effectively promote melt coating of the adhesive composition precursor, a melt flow index of at least 150 g / 10 minutes is particularly suitable. If the MFR is too large, the cohesion of the cured composition may decrease, with an MFR of 200 to 1000 g / 10 minutes being most particularly suitable. "MFR" herein is a value measured according to Japanese Industrial Standard (JIS) K6760. The weight average molecular weight of the ethylene-glycidyl (meth) acrylate copolymer should be chosen such that the MFR falls within the above range.

The minimum proportion of ethylene-glycidyl (meth) acrylate copolymer in the adhesive composition is 10% by weight and the maximum ratio is 95% by weight. If it is less than 10% by weight, the effect of increased cohesion of the cured product may decrease, and if it exceeds 95% by weight, the adhesion may be reduced during the thermo-compression bonding. From this aspect, the minimum ratio is 30% by weight, particularly suitably 40% by weight, and the maximum ratio is 88% by weight, particularly suitably 85% by weight. The ratios are based on the total weight of the ethylene-glycidyl (meth) acrylate copolymer, the optional ethylene-alkyl (meth) acrylate copolymer described below, and the carboxyl group-containing rosin.

The adhesive composition may also contain an ethylene-alkyl (meth) acrylate copolymer in addition to the ethylene-glycidyl (meth) acrylate copolymer. When using ethylene-alkyl (meth) acrylate copolymers, the copolymer allows the adhesive composition precursor to melt at relatively low temperatures to facilitate melt coating and to increase the thermal adhesion of the adhesive composition. In addition, the electron beam irradiation forms a crosslinked structure with the ethylene-glycidyl (meth) acrylate copolymer and / or the ethylene-alkyl (meth) acrylate copolymer, so that the elastic modulus is improved during the thermocompression bonding of the adhesive composition. In addition, since the ethylene-alkyl (meth) acrylate copolymer has lower hygroscopicity than ethylene-glycidyl (meth) acrylate, it also increases the water resistance of the adhesive composition or precursor thereof. Generally speaking, the ethylene-alkyl (meth) acrylate copolymer will have a lower softening point than the ethylene-glycidyl (meth) acrylate copolymer, so that the internal stress when the cured composition is subjected to a heating cycle It will improve the adhesion performance.

Ethylene-alkyl (meth) acrylate copolymers can be obtained, for example, by polymerizing monomer mixtures containing alkyl (meth) acrylate monomers and ethylene monomers as starting monomers. As long as the effects of the present invention are not impaired, third monomers such as propylene or vinyl acetate can also be used in addition to the monomers described above.

The alkyl group of the alkyl (meth) acrylate contains at least one and up to four carbon atoms. When the number of carbon atoms of the alkyl group exceeds 4, it may be difficult to increase the modulus of elasticity of the crosslinked composition.

Useful ethylene-alkyl (meth) acrylate copolymers include copolymers of alkyl (meth) acrylates and ethylene, and terpolymers of alkyl (meth) acrylates, vinyl acetate and ethylene. Such copolymers comprise repeating units polymerized from monomer mixtures of alkyl (meth) acrylates and ethylene in a proportion generally at least 50% by weight, particularly suitably at least 75% by weight relative to the total polymer.

The polymerization ratio of alkyl (meth) acrylate (G) and ethylene (E) in the repeating unit is preferably 60:40 to 1:99, particularly suitably 50:50 to 5:95. If the ethylene content is too low, the improved elastic modulus by electron beam crosslinking may decrease, and if the ethylene content is too high, the adhesion performance may decrease. The ethylene-alkyl (meth) acrylate copolymer can be used as a single species or as a mixture of two or more species.

The MFR of the ethylene-alkyl (meth) acrylate copolymer, measured at 190 ° C., is generally at least 1 g / 10 minutes, particularly suitably at least 150 g / 10 minutes, most particularly suitably from 200 to for the reasons mentioned above. 1,000 g / 10 min. The weight average molecular weight of the copolymer is chosen such that the MFR falls within this range.

If ethylene-alkyl (meth) acrylate copolymers are present in the adhesive composition, their proportions will generally not exceed 80% by weight. If it exceeds 80% by weight, the curability of the composition may decrease. The proportion of ethylene-alkyl (meth) acrylate copolymers is generally from 4 to 80% by weight, particularly suitably from 10 to 60% by weight and most particularly suitably from 15 to 50% by weight. The ratio is based on the total weight of the ethylene-glycidyl (meth) acrylate copolymer, the ethylene-alkyl (meth) acrylate copolymer and the carboxyl group-containing rosin.

The carboxyl group-containing rosin reacts with the ethylene-glycidyl (meth) acrylate copolymer during the thermosetting operation to thermally cure the adhesive composition and enhance adhesion performance. Useful rosins are gum rosin, wood rosin, tallow rosin, or their chemically modified forms, such as polymerized rosin.

The acid value of rosin is preferably 100 to 300 mgKOH / g. If the acid value is too low, rosin may degrade reactivity with the ethylene-glycidyl (meth) acrylate copolymer, adversely affecting the curability of the composition, while if the acid value is too high, stability during thermoforming is compromised. Can be. An “acid value” herein is the number of milligrams of potassium hydroxide required to neutralize 1 g of sample.

The softening point of the rosin is 50 to 200 ° C, particularly suitably 70 to 150 ° C. If the softening point is too low, it may react with the ethylene-glycidyl (meth) acrylate copolymer during storage, leading to a decrease in storage stability. If the softening point is too high, the reactivity may be lowered, thereby reducing the curability of the composition. As used herein, the term "softening point" means a numerical value measured according to JIS K6730.

The proportion of rosin in the adhesive composition will typically be from 1 to 20% by weight. If less than 1% by weight, the curability and thermal adhesiveness of the composition may decrease, and if higher than 20% by weight, the adhesive performance of the cured composition may be degraded. From this aspect, 2 to 15% by weight is particularly suitable, and 3 to 10% by weight is more particularly suitable. The ratios are based on the total weight of the ethylene-glycidyl (meth) acrylate copolymer, the ethylene-alkyl (meth) acrylate copolymer (if included), and the carboxyl group-containing rosin.

A single rosin can be used or two or more mixtures can be used. Unless the effect of this invention is impaired, carboxyl group-containing rosin can be used in combination with rosin which is substantially free of carboxyl group.

To the extent that the effects of the present invention are not impaired, the adhesive composition may also contain any of various additives in addition to the above components. Examples of such additives include antioxidants, ultraviolet absorbers, fillers (inorganic fillers, conductive particles and pigments, etc.), lubricants such as waxes, rubber components, thickeners, crosslinking agents and curing accelerators.

The curing reaction is carried out at a temperature of 150 ° C. or higher by heating for a period of 1 minute to 24 hours until the adhesive sheet can produce sufficient adhesion (eg, 4-15 kg / 25 mm or more). .

The adhesive sheet used for the present invention can be produced in the following exemplary manner. First, an adhesive composition precursor is prepared comprising an ethylene-glycidyl (meth) acrylate copolymer and a rosin, and optionally an ethylene-alkyl (meth) acrylate copolymer. The precursor is then melt coated onto the substrate to form a sheet of precursor. Thereafter, the precursor sheet is irradiated with an electron beam to form a crosslinked structure between the molecules of the ethylene unit-containing polymer, thereby producing an adhesive sheet having the required thermal conductivity.

The composition precursors described above are generally prepared by mixing the starting material components substantially uniformly using a kneading or mixing device. The apparatus used may be a kneader, roll mill, extruder, planetary mixer or homogenizer or the like. The mixing temperature and time are chosen such that substantially no reaction occurs between the ethylene-glycidyl (meth) acrylate copolymer and the rosin, and generally the temperature will be 20 to 120 ° C. and the time will be 1 minute to 2 hours.

The composite modulus η ^* of the composition precursor, measured under conditions of 120 ° C. and 6.28 rad / sec, is 500 to 1,000,000 poise, particularly suitably 1,200 to 10,000 poise. If the composite modulus η ^* is too low, it may be difficult to mold to a predetermined thickness, and if too high, it may be difficult to mold continuously.

A liner such as a release paper or a release film can be used as the substrate. Melt coating is typically performed at temperatures of 60-120 ° C. Conventional coating apparatuses are useful for the adhesive sheet of the present invention, and examples thereof include, but are not limited to, knife coaters or die coaters. Sheet-like precursors can also be formed by extrusion without the use of a substrate. Electron beam irradiation is usually carried out using an electron beam accelerator with an acceleration voltage of 150 to 500 keV and an absorbed dose of typically 10 to 400 kGy. Thereafter, through holes are opened at predetermined positions of the adhesive sheet by means such as blue holes to form through opening regions and the like.

The thickness of the adhesive sheet is preferably about 0.001 mm to about 5 mm, more preferably 0.005 to 0.5 mm. When the sheet is too thin, the handling of the adhesive sheet tends to be difficult, and when too thick, the crosslinking becomes uneven in the thickness direction, and the reliability as the adhesive may be deteriorated.

In the case of the conductive and thermally conductive thermosetting adhesive sheet of the present invention, a low melting point solder is disposed in the through opening region formed in the adhesive sheet. Low melting solders generally have a melting point of 150 ° C. or less, particularly preferably less than 120 ° C. The solder is placed in the opening area in the adhesive sheet formed in the above manner, and if necessary contacted through a release liner by appropriate means, such as a binder, to obtain a thermosetting adhesive sheet according to the present invention. The contact bonding temperature is 120 ° C to 150 ° C. In this temperature range, the solder melts and flows, and the thermosetting adhesive composition is also sufficiently melted to produce melt adhesion between the solder and the adhesive composition without significant curing of the adhesive composition. In addition, since the solder and the adhesive composition are melt bonded, the solder is not riveted because the solder is not riveted. As long as the melting point is 150 ° C. or lower, there is no particular limitation on the low melting solder. Useful solders include those described in Electronic Material Soldering Techniques, 1st edition, 5th printing, p. 114. Suitable solders are formed from combinations of materials such as Sn / Bi, Sn / Bi / Pb, Sn / Bi / Pb / Cd, Sn / Bi / Zn and Sn / Bi / Pb / Cd / In and the like. Also useful are Sn / In, Sn / Pb / In, etc., which have a low melting point below 150 ° C., commercially available from the solder manufacturer and required. In particular, Sn / In (melting point: 117 ° C) and Sn / Bi (melting point: 139 ° C) are preferable because they do not contain harmful elemental lead or cadmium.

One use for the liner-adhesive adhesive sheet obtained in the manner described above is a bond between two adherends to form a three layer bond structure.

First, after removing a liner from an adhesive sheet, the laminated body laminated | stacked in the order of a 1st adherend, an adhesive sheet, and a 2nd adherend is interposed between a 1st and 2nd adherend. The laminate is then thermo-compression bonded at a temperature of 120 to 300 ° C. and a pressure of 0.1 kg / cm ² to 100 kg / cm ² to form a bonding structure in which the three layers are contact bonded together. This method allows the two adherends to be joined together with sufficient adhesion in the time range of only 0.1 seconds to 30 seconds.

The thermosetting adhesive sheet of the present invention essentially exerts sufficient adhesive force by the above-mentioned heat-compression bonding, but performs post curing to achieve higher adhesive force. That is, in the above bonding method, the bonding structure is post-cured under temperature conditions of generally 120 ° C. or higher, usually 130 ° C. to 300 ° C., for a time ranging from 1 minute to 24 hours. Preferred conditions for promoting the post cure step are 140 to 200 ° C. for 30 minutes to 1.2 hours.

The conductive and thermally conductive thermosetting adhesive sheet of the present invention is also used as a heat dissipation adhesive sheet for bonding between an electronic element such as, for example, an IC chip, and a heat dissipation component such as a heat sink for dissipating heat generated from the electronic element.

2 is an exploded perspective view of one embodiment of an electronic component using a thermosetting adhesive sheet according to the present invention. After being laminated to the heat sink (5), the laminated structure has a thermosetting adhesive sheet (1), an adhesive region (3), an IC chip of the present invention having a region (s) 2 provided with a low temperature solder in the through hole. 4) and reinforcement 6 with openings for accommodating the IC chip 4. The adhesive sheet 1, which is a thermosetting adhesive sheet according to the present invention, has the same opening and TAB 7 as the reinforcing material 6, and the contact bonding is carried out in the above-mentioned region at a temperature of 120 to 300 캜. At least a portion of the solder holding region 2 of the adhesive sheet 1 corresponds to the region disposed on the IC chip 4. This provides conductivity and high thermal conductivity, and also allows the heat generated from the chip to be released satisfactorily. The adhesive sheet 1 also has solder disposed in the laminated area on the reinforcement 6. Since the stiffener 6 is formed of a metal conductor such as copper, the TAB 7 is electrically continuous with the adhesive sheet 1, the stiffener 6 and the adhesive sheet 1 having the same opening as the stiffener 6 It is a state. This eliminates the need for solder conductive paths at the ends, which were previously required for electronic components. Therefore, in the case of using the thermosetting adhesive sheet of the present invention, since the solder has to be disposed in a preservable manner only in an area where conductivity and thermal conductivity are required, the amount of solder used can be reduced and high thermal conductivity can be achieved. The adhesive sheet of the present invention can also be used for bonding IC chips and reinforcements with heat sinks to simplify the electronic component manufacturing steps.

The invention is further illustrated by the following examples.

Preparation of Adhesive Sheet

First, 70 parts by weight of ethylene-glycidyl methacrylate copolymer CG5001 (BonDFAST®, Sumitomo Chemical Co., Ltd., MFR = 350 g / 10 min), 25 weight Part ethylene-ethyl acrylate copolymer NUC6070 (manufactured by Nihon Unica Co., Ltd., MFR = 250 g / 10 min) and 5 parts by weight of carboxyl-containing rosin KR85 (Arakawa Chemical Industries, Ltd.) Industries, Ltd.), acid value = 170 mgKOH / g) were mixed and kneaded for 7 minutes at a temperature of 120 ° C. The composition was then 100 μm release-treated polyethylene terephthalate (PET) using a knife coater at 150 ° C. The coating was made on a liner to prepare a 50 μm thermosetting adhesive sheet precursor The composition of the precursors is shown in Table 1. The adhesive sheet precursor was irradiated with an electron beam at absorbing beneficiation of 200 kV and 150 kGy to thermoset on the PET liner. An adhesive sheet was obtained. This adhesive sheet was referred to as a first adhesive sheet (adhesive sheet of Comparative Example 1).

After kneading 12.5 parts by weight of CG5001 and 87.5 parts by weight of AgC2001 (silver powder of Fukuda Metal Foil & Powder Co., Ltd.) as described above, the kneaded mixture was kneaded onto a PET liner. Coating gave an adhesive sheet precursor. The composition of the precursors is shown in Table 1 below. The adhesive sheet precursor was further irradiated with an electron beam in the same manner as described above to obtain a thermosetting adhesive sheet. This adhesive sheet was called Adhesive Sheet 2 (Adhesive Sheet of Comparative Example 2).

Composition of Adhesive Sheet Precursor Composition (weight ratio) Adhesive Sheet 1 and 3 Precursors CG5001 / NUC6070 / KR85 = 70/25/5 Adhesive sheet 2 precursor CG5001 / AgC2001 = 12.5 / 87.5

The adhesive sheet 1 was cut | disconnected to the dimension shown in FIG. 3, and the sheet in which the through-opening area was formed was obtained. Replaced the release-treated PET liner. Thereafter, a low-melting solder ribbon (Senju Metal Industry Co., Ltd.) having a thickness of 100 µm, a width of 1 mm, and a melting point of 114 ° C. was cut to a length of 8 mm, and this was an adhesive sheet. It was placed in the through-opening region of 1 and brought into contact with the binder to obtain a thermosetting adhesive sheet according to the present invention. The contact bonding pressure was 2 kg / cm ² , the contact bonding temperature was 127 ° C., and the contact bonding time was 3 seconds. Each adhesive sheet obtained from the adhesive sheet 1 was called adhesive sheet 3 (adhesive sheet of Example 1).

Preparation of Sample for Measuring Thermal Conductivity

The PET liner was released from each of the adhesive samples described above, and each adhesive sample was used to bond between two 50 μm thick copper plates. For Example 1, two adhesive sheets were used for bonding, but only one sheet was used for Comparative Examples 1 and 2. The contact bonding pressure was 2 kg / cm ² , the contact bonding temperature was 175 ° C., and the contact bonding time was 10 seconds. Each sample was cut into a 10 mm x 10 mm with a fret saw to prepare a sample for thermal conductivity measurement. A 100 mm square 490 μm thick stainless steel plate (SUS304 (BA)) was also used as a control sample for thermal conductivity measurement. The structure of the measurement sample and the control sample of Example 1 and Comparative Examples 1 and 2 are shown in Table 2 below.

Structure of Sample for Measurement Adhesive sheet Thickness (㎛) Sample form Used copper plate Example 1 Adhesive Sheet 3 100 (50 x 2) Bonding both sides with copper plate Thickness 500㎛ Comparative Example 1 Adhesive Sheet 1 50 Bonding both sides with copper plate Thickness 500㎛ Comparative Example 2 Adhesive Sheet 2 50 Bonding both sides with copper plate Thickness 500㎛ Control SUS304 (BA) 490 Equipment only radish

Measurement result Temperature difference between upper jig thermocouple (℃) Temperature difference between samples (℃) Sample thermal resistance (℃ / W) Sample thermal conductivity (W / mK) Example 1 10.8 (∼83 ± 12W) 10.6 ～ 0.13 ± 0.02 7.8 ± 1 Comparative Example 1 2.6 (~ 20 ± 3W) 38.2 1.91 ± 0.3 0.26 ± 0.04 Comparative Example 2 3.2 (~ 25 ± 4W) 24.1 0.96 ± 0.15 5.2 ± 0.8 Control 2.8 (∼21 ± 3W) 6.3 0.29 ± 0.04 17 ± 2

Thermal conductivity measurement

An apparatus for measuring the thermal conductivity based on the vertical comparison method was manufactured, and the thermal conductivity of each sample was measured. 4 shows a schematic diagram of this device. As shown in the figure, the sample S was interposed between two jigs and fixed. The jig J used was a calendering copper rod (JIS C1100, cross section diameter 10 mm). The upper jig was heated with a heater (H) of WATLOW Co., and the heat flowing from the heated jig through the sample to the lower jig was measured. Two K-thermocouples (T) having a tip diameter of 500 µm were inserted into the jig center with a 4 mm gap to measure heat flow through the jig. A water cooler was mounted on the bottom of the opposing jig to remove heat from the sample. The amount of heat flowing through the jig (W) is 391 W / mK as a value of the thermal conductivity of the calendering copper rod, using the cross-sectional area (m ² ) of the calendering copper rod and the distance and temperature difference between the two thermocouples (° C. (K)). Was measured.

The sample to be measured was interposed between the above-mentioned jigs, fixed using silver paste, and a dead load was applied with a weight of 3 kg. Each thermocouple (T) was mounted on each surface of the sample using a small amount of instant binder to measure the temperature on both surfaces of the sample. After heating the structure phase using a heater (H), the temperature change at each measuring point stabilized after 1 hour and the temperature was measured on both points of the upper jig and on both surfaces of the sample. A glass lid was used on the measurement portion to minimize the effect of room temperature. The results are shown in Table 3 above.

From the results for the control samples shown in Table 3, the thermal conductivity of SUS304 measured by the method was approximately 17 ± 2 W / mK, similar to the known value 16.5 W / mK [Thermoconductive Engineering Materials, Revised 4th Edition, p.318]. The effectiveness of the method was then confirmed. As shown in Table 3, the thermal resistance of Example 1 was lower than that of Comparative Examples 1 and 2, indicating that the thermosetting adhesive sheet of the present invention has a high thermal conductivity suitable for heat radiation applications. Thus, the amount of metal used can be reduced while obtaining the same degree of heat dissipation, thereby providing an economic advantage.

When the thermosetting adhesive sheet of the present invention is applied for heat dissipation for electronic components in electronic components formed by the TAB system, it is possible to combine the electronic components and the reinforcement on the heat sink using a single adhesive sheet, so that the manufacturing steps are simplified and excellent. Economic benefits are provided.

Claims (5)

a) a thermosetting adhesive composition comprising an ethylene-glycidyl (meth) acrylate copolymer and a carboxyl group-containing rosin, wherein crosslinking is formed between the ethylene of the copolymer by electron beam radiation, one at a predetermined position The thermosetting adhesive sheet which has two main surfaces in which the above-mentioned through opening area | region is formed, And b) low melting solder disposed within said at least one through opening region formed in a predetermined position, Thermosetting adhesive sheet having conductivity and thermal conductivity. The thermosetting adhesive sheet according to claim 1, wherein the thermosetting adhesive composition further comprises an ethylene-alkyl (meth) acrylate copolymer. The thermosetting adhesive sheet of claim 1, wherein the adhesive sheet further comprises a release sheet on one or more surfaces thereof. An electronic structure comprising the thermosetting adhesive sheet of claim 1, wherein the thermosetting adhesive sheet of claim 1 is a heat dissipation adhesive sheet positioned between the electronic element and the heat dissipation means and attached to the heat dissipation means. The electronic structure of claim 4, wherein the predetermined position of the through opening region is in contact with the electronic element.