JP2005255829A - Heat-releasable adhesive sheet and processing method of adherend - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a heat-releasable adhesive sheet which enables processing of an adherend while preventing displacement or deformation of the adherend in processing of the adherend including a pressurizing step and enables easy release of the processed product after processing. <P>SOLUTION: The heat-releasable adhesive sheet has a heat-expandable adhesive layer containing a foaming agent and formed on at least one side of a substrate and also has an adhesiveness-protecting layer on the surface of the heat-expandable adhesive layer, wherein the adhesiveness-protecting layer has a shear modulus of ≥1×10<SP>6</SP>Pa at 23°C and can be released at the interface between it and the heat-expandable adhesive layer when the heat-expandable adhesive layer is heat-expanded through heat-treatment. The adhesiveness-protecting layer may have a shear modulus of ≥1×10<SP>6</SP>Pa at 80°C, is preferably composed of only organic components, and may have a thickness of 0.05-100 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-peelable pressure-sensitive adhesive sheet, a method for processing an adherend using the heat-peelable pressure-sensitive adhesive sheet, and the like.

  The recent demand for electronic components is miniaturization and refinement of the components themselves. For example, in ceramic capacitors, miniaturization represented by so-called “0603” or so-called “0402” and high stacking greatly exceeding several hundred layers. The increase in capacity due to the increase is becoming more prominent. In particular, in the field of lamination of ceramic pre-fired sheets (green sheets) such as ceramic capacitors, precision during processing has been demanded due to miniaturization and precision.

  For example, as an example of a manufacturing process of a ceramic capacitor, (1) an electrode printing process on a green sheet, (2) a lamination process, (3) a pressing process (pressing press process), (4) a cutting process, 5) There is a firing step, and the laminating step (2) and the pressurizing step (3) are repeated a predetermined number of times, and then the manufacturing step moves to the cutting step (4).

  In such a process, the required accuracy includes, for example, the accuracy of electrode printing in the electrode printing step (1) on the green sheet, and the accuracy of the electrode position in the lamination step (2). In the pressurizing step (3), the green sheet is deformed by pressurization and the electrode position is prevented from being displaced due to displacement, and in the cutting step (4), the accuracy due to cutting is cited. It is done. If even one of these processes is inaccurate, the product will be defective and productivity will be reduced.

  Among them, the electrode printing process (1), the lamination process (2), and the cutting process (4) on the green sheet require mechanical accuracy, and can be handled by improving the device and improving accuracy. Is possible. However, in the pressurization step (3), a displacement due to the deformation of the green sheet occurs due to the pressurization at the time of pressurization (pressurization press), which is the green sheet electrode laminated in the lamination step (2). The positional deviation may affect the accuracy of the electrode position.

  Currently, in the laminating step (2), it is generally laminated on a polyethylene terephthalate film (PET film) or an adhesive tape. From the viewpoint of adhesiveness, a method of laminating on an adhesive tape has been widely used.

  As such an adhesive tape, it has adhesive strength at normal temperature and firmly adheres (fixes) the lamination process, pressurization process, and cutting process, and after the cutting process, it is adhesive by heating or irradiation with ultraviolet rays. What has a function which can be made to peel and to peel is used. Therefore, for example, a heat-peelable pressure-sensitive adhesive sheet (see, for example, Patent Documents 1 to 5) provided with a thermally expandable pressure-sensitive adhesive layer on at least one surface of a substrate, an ultraviolet-curing peelable pressure-sensitive adhesive sheet, a weak pressure-sensitive adhesive tape, etc. Is used. Specifically, in the case of a heat-peelable pressure-sensitive adhesive sheet, the heat-peelable pressure-sensitive adhesive sheet is a combination of adhesiveness before heating and peelability after heating. By foaming or expanding the heat-expandable microspheres in the expandable adhesive layer, the surface of the heat-expandable adhesive layer changes to an uneven shape, so that the adhesion area (contact area) with the adherend (article) The adhesive force can be reduced by the decrease, and thus the adherend can be easily peeled (separated).

Japanese Patent Publication No. 50-13878 Japanese Patent Publication No.51-24534 JP-A-56-61468 JP-A-56-61469 JP 60-252681 A

  However, as described above, when an adhesive tape is used when manufacturing a miniaturized or refined ceramic capacitor, the adhesive layer of the adhesive tape is deformed during the pressurizing process and follows the deformation. As a result, the green sheet is deformed, which may result in poor electrode position accuracy. This displacement due to pressurization tends to hardly occur on a material having a high elastic modulus at room temperature such as on a PET film.

Accordingly, an object of the present invention is to process an adherend while suppressing or preventing displacement and deformation of the adherend even if an adhesive sheet is used during the processing of the adherend including a pressing step. It is possible to provide a heat-peelable pressure-sensitive adhesive sheet that can easily peel off a processed product after processing, and a method for processing an adherend using the heat-peelable pressure-sensitive adhesive sheet.
Another object of the present invention is to suppress or prevent misalignment and deformation of an adherend even when a pressure-sensitive adhesive sheet is used during processing including a laminating step or a cutting step together with a pressurizing step, and laminating. A heat-peelable pressure-sensitive adhesive sheet that can exhibit excellent adhesiveness in the process or cutting step, and can easily peel off a processed product after processing, and an adherend using the heat-peelable pressure-sensitive adhesive sheet It is in providing the processing method of.
Still another object of the present invention is to provide a heating process that can eliminate the residue of the pressure-sensitive adhesive sheet in the firing step of firing the processed product even if a part of the pressure-sensitive adhesive sheet remains on the processed product after processing. An object of the present invention is to provide a peelable adhesive sheet and a method for processing an adherend using the heat peelable adhesive sheet.
Another object of the present invention is to provide a heat-peelable pressure-sensitive adhesive sheet capable of effectively improving the precision of parts, responding to miniaturization, and improving productivity by improving yield prevention, and the heat-peelable pressure-sensitive adhesive sheet An object of the present invention is to provide a method for processing an adherend using a metal.

  As a result of diligent studies to achieve the above object, the present inventors have found that in the ceramic capacitor manufacturing process, an adhesive protective layer having a specific shear elastic modulus and a specific configuration on the thermally expandable adhesive layer. When a heat-peelable pressure-sensitive adhesive sheet having a structure is used, it is possible to suppress or prevent the green sheet from being displaced or deformed in the laminating process or pressurizing process, and to be firmly fixed in the cutting process. In addition, it can be easily peeled after cutting, and further, when the adhesive protective layer is composed entirely of organic components, the heat-peelable pressure-sensitive adhesive sheet is peeled off from the processed product as an adherend, It has been found that even if the adhesive protective layer remains in the processed product, the adhesive protective layer can be burned off in the baking step of the processed product. The present invention has been completed based on these findings.

That is, the present invention relates to a heat-peelable pressure-sensitive adhesive sheet in which a heat-expandable pressure-sensitive adhesive layer containing a foaming agent is formed on at least one surface of a substrate, and the surface of the heat-expandable pressure-sensitive adhesive layer is sheared at 23 ° C. It has an adhesive protective layer that has an elastic modulus of 1 × 10 ⁶ Pa or more and can be peeled off at the interface with the thermally expandable adhesive layer when the thermally expandable adhesive layer is thermally expanded by heat treatment. A heat-peelable pressure-sensitive adhesive sheet is provided.

The adhesive protective layer preferably further has a shear elastic modulus at 80 ° C. of 1 × 10 ⁶ Pa or more. Moreover, it is preferable that all the adhesive protective layers are comprised by the organic component. Furthermore, the thickness of the adhesive protective layer is preferably 0.05 to 100 μm.

  The present invention is also a method of processing an adherend using a heat-peelable pressure-sensitive adhesive sheet, the adherend being bonded onto the adhesive protective layer of the heat-peelable pressure-sensitive adhesive sheet, Provided is a method for processing an adherend, wherein the adherend is processed by performing a processing treatment. As the adherend, electronic parts can be preferably used.

  In the method for processing an adherend according to the present invention, the adherend is a green sheet for a ceramic capacitor, and may include a green sheet laminating step.

  Furthermore, the present invention provides an electronic component manufactured using the method for processing an adherend, and a laminate manufactured using the method for processing the adherend. A ceramic capacitor is provided.

  According to the heat-peelable pressure-sensitive adhesive sheet of the present invention, even when a pressure-sensitive adhesive sheet is used at the time of processing the adherend including a pressurizing step, the adherend is suppressed or prevented from being displaced or deformed. In addition, after the processing, the processed product can be easily peeled off. Moreover, even if a pressure-sensitive adhesive sheet is used during processing including a laminating step or a cutting step together with a pressurizing step, it can suppress or prevent displacement and deformation of the adherend, and is excellent in the laminating step or the cutting step. In addition, the processed product can be easily peeled off after processing. Furthermore, even if a part of the pressure-sensitive adhesive sheet remains in the processed product after processing, the residue of the pressure-sensitive adhesive sheet can be lost in the baking step of baking the processed product. Therefore, it is possible to effectively improve productivity by improving component accuracy, dealing with downsizing, and improving yield prevention.

Embodiments of the present invention will be described below in detail with reference to the drawings as necessary. In addition, the same code | symbol may be attached | subjected to the same member, a part, etc.
[Heat-release adhesive sheet]
As shown in FIG. 1, the heat-peelable pressure-sensitive adhesive sheet of the present invention has a base material and a heat-expandable pressure-sensitive adhesive containing heat-expandable microspheres as a foaming agent formed on at least one surface of the base material. And an adhesive protective layer formed on the thermally expandable adhesive layer, and the adhesive protective layer has a shear elastic modulus at 23 ° C. of 1 × 10 ⁶ Pa or more (preferably 5 × 10 ⁶ Pa or more, more preferably 1 × 10 ⁷ Pa or more), and when the thermally expandable pressure-sensitive adhesive layer is thermally expanded by heat treatment, it can be peeled off at the interface with the heat-expandable pressure-sensitive adhesive layer. ing. FIG. 1 is a schematic sectional view partially showing an example of the heat-peelable pressure-sensitive adhesive sheet of the present invention. In FIG. 1, 1 is a heat-peelable pressure-sensitive adhesive sheet, 2 is a substrate, 3 is a heat-expandable pressure-sensitive adhesive layer, 4 is an adhesive protective layer, 5 is a rubbery organic elastic layer, and 6 is a separator (release liner). The adhesive protective layer 4 has a shear modulus (23 ° C.) of 1 × 10 ⁶ Pa or more, and has a structure that can be peeled off at the interface with the thermally expandable adhesive layer when the thermally expandable adhesive layer is thermally expanded. doing.

Specifically, the heat-peelable pressure-sensitive adhesive sheet 1 shown in FIG. 1 includes a base material 2, a rubber-like organic elastic layer 5 formed on one surface (one surface) of the base material 2, and the rubber-like material. A heat-expandable pressure-sensitive adhesive layer 3 formed on the organic elastic layer 5, a pressure-sensitive adhesive protective layer 4 formed on the heat-expandable pressure-sensitive adhesive layer 3, and the pressure-sensitive adhesive protective layer 4, and The adhesive protective layer 4 has a form protected by a separator 6, and the adhesive protective layer 4 has a characteristic that the shear elastic modulus (23 ° C.) is 1 × 10 ⁶ Pa or more. In addition, when the thermally expandable pressure-sensitive adhesive layer 3 is thermally expanded, the heat-expandable pressure-sensitive adhesive layer 3 can be peeled off at the interface with the heat-expandable pressure-sensitive adhesive layer 3.

  The heat-peelable pressure-sensitive adhesive sheet 1 shown in FIG. 1 has a rubber-like organic elastic layer 5, but this rubber-like organic elastic layer 5 can be arbitrarily used. For example, the heat-expandable pressure-sensitive adhesive layer 3 It is preferably used from the viewpoints of improving the anchoring force at the time of thermal expansion and the expression of the undulation structure.

As described above, the heat-peelable pressure-sensitive adhesive sheet of the present invention has a shear elastic modulus (23 ° C.) of 1 × 10 ⁶ Pa or more on the heat-expandable pressure-sensitive adhesive layer and heat-heats the heat-expandable pressure-sensitive adhesive layer by heat treatment. Since an adhesive protective layer is formed that can be peeled off at the interface with the thermally expandable adhesive layer when expanded, pressurization (pressing press) is performed at room temperature in the pressurizing step (pressing press step). By doing so, the pressure-sensitive adhesive layer absorbs the pressure at the time of pressurization, and the deformation of the heat-expandable pressure-sensitive adhesive layer can be suppressed or prevented. Therefore, the adherend that is attached to the pressure-sensitive protective layer Deformation can be suppressed or prevented. Therefore, it is possible to improve the accuracy of the processed product or part that has been processed, to cope with downsizing, and to prevent the yield and improve the productivity.

Of course, after processing, the processed product can be easily peeled from the heat-peelable pressure-sensitive adhesive sheet by heat treatment. In particular, the adhesive protective layer has a characteristic that the shear modulus at 23 ° C. is 1 × 10 ⁶ Pa or more (preferably 5 × 10 ⁶ Pa or more, more preferably 1 × 10 ⁷ Pa or more). , the shear modulus at 80 ° C. has a characteristic which is 1 × 10 ⁶ Pa or more (preferably ^{2 × 10 6 Pa~1 × 10 9} Pa), by the heat treatment, the heat-expandable pressure-sensitive adhesive layer adhesive Peeling at the interface with the protective layer can be performed more easily.

  In this peeling, the adhesive protective layer is transferred to the processed product, but the adhesive protective layer can be burned off in the firing step. Therefore, for example, in the ceramic capacitor manufacturing process, etc., since the green sheet is subjected to a firing process after being subjected to various processing, an accurate ceramic capacitor is obtained without leaving an adhesive protective layer on the green sheet. Can do.

[Base material]
The substrate can be used as a support matrix such as a thermally expandable adhesive layer. Examples of the substrate include paper-based substrates such as paper; fiber-based substrates such as woven fabrics, nonwoven fabrics, felts, and nets; metal-based substrates such as metal foils and metal plates; plastics such as plastic films and sheets. Base materials; rubber base materials such as rubber sheets; foams such as foam sheets, and laminates thereof (particularly, laminates of plastic base materials and other base materials, and plastic films (or sheets)) An appropriate thin leaf body such as a laminate of the above can be used. As a base material, what is excellent in heat resistance which does not melt at the heat processing temperature of a thermally expansible adhesive layer is preferable from points, such as the handleability after a heating. As the substrate, a plastic substrate such as a plastic film or sheet can be suitably used. As a material in such a plastic film or sheet, for example, an α-olefin such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA) or the like is used as a monomer component. Olefin-based resins: Polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); polyvinyl chloride (PVC); polyphenylene sulfide (PPS); polyamide (nylon), wholly aromatic Examples thereof include amide resins such as polyamide (aramid); polyetheretherketone (PEEK). These materials can be used alone or in combination of two or more.

  In addition, when a plastic-type base material is used as a base material, you may control deformability, such as elongation rate, by extending | stretching process etc. Moreover, as a base material, when using a radiation curable substance for a thermally expansible adhesive layer etc., it is preferable to use what does not inhibit transmission of a radiation.

  The thickness of the substrate can be appropriately selected according to the strength, flexibility, purpose of use, and the like. For example, it is generally 1000 μm or less (for example, 1 to 1000 μm), preferably 1 to 500 μm, more preferably 3 to 3 μm. Although it is 300 micrometers, especially about 5-250 micrometers, it is not limited to these. In addition, the base material may have a single layer form or may have a laminated form.

  In order to improve the adhesion with the thermally expandable adhesive layer, etc., the surface of the base material is subjected to conventional surface treatments such as corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage impact exposure, and ionizing radiation treatment. An oxidation treatment or the like by a physical or physical method may be performed, or a coating treatment or the like by a primer may be performed. Moreover, in order to give peelability with a thermally expansible adhesive layer etc., the coating process by release agents, such as silicone resin and a fluorine resin, etc. may be given, for example.

  Note that a thermally expandable adhesive layer is provided on at least one surface (one surface or both surfaces) of the substrate. Moreover, it can also be set as the form which embed | buried the base material inside the thermally expansible adhesive layer.

[Heat-expandable adhesive layer]
The heat-expandable pressure-sensitive adhesive layer contains at least a pressure-sensitive adhesive for imparting tackiness and a foaming agent for imparting heat-expandability. Therefore, for example, when a heat-peelable pressure-sensitive adhesive sheet is attached to an adherend (for example, a member or component such as a semiconductor wafer), the heat-expandable pressure-sensitive adhesive layer is heated at any time, and a foaming agent (heat By expanding and / or expanding the expandable microspheres, etc., the thermally expandable adhesive layer expands. By this expansion, the adhesion area (contact area) between the thermally expandable adhesive layer and the adhesive protective layer is increased. The adhesive force by the heat-expandable pressure-sensitive adhesive layer decreases, and the heat-peelable pressure-sensitive adhesive sheet can be easily peeled off from the adherend to which it is attached. At this time, the adhesive protective layer is transferred to the adherend. In the peeling of such a heat-peelable pressure-sensitive adhesive sheet, if a foaming agent that is not microencapsulated is used as the foaming agent contained in the thermally expandable pressure-sensitive adhesive layer, good peelability cannot be stably exhibited. .

  The foaming agent used in the heat-expandable pressure-sensitive adhesive layer is not particularly limited, but heat-expandable microspheres can be suitably used. A foaming agent can be used individually or in combination of 2 or more types. The heat-expandable microsphere is not particularly limited, and can be appropriately selected from known heat-expandable microspheres (such as various inorganic heat-expandable microspheres and organic heat-expandable microspheres). As the thermally expandable microspheres, a microencapsulated foaming agent can be suitably used from the viewpoint of easy mixing operation. Examples of such thermally expandable microspheres include microspheres in which substances such as isobutane, propane, and pentane that are easily gasified and expanded by heating are encapsulated in an elastic shell. The shell is often formed of a hot-melt material or a material that is destroyed by thermal expansion. Examples of the substance forming the shell include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone. Thermally expandable microspheres can be produced by a conventional method such as a coacervation method or an interfacial polymerization method. Examples of thermally expandable microspheres include commercial products such as “Matsumoto Microsphere” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.).

  In addition, a thermal expansion aid can be used with a thermally expansible microsphere as needed.

  In the present invention, as the foaming agent, foaming agents other than the thermally expandable microspheres can also be used. As such a foaming agent, various foaming agents such as various inorganic foaming agents and organic foaming agents can be appropriately selected and used. Typical examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, various azides and the like. Representative examples of organic foaming agents include, for example, water; chlorofluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodicarbonamide, and barium azodi. Azo compounds such as carboxylate; hydrazine compounds such as p-toluenesulfonyl hydrazide, diphenylsulfone-3,3'-disulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide), allyl bis (sulfonyl hydrazide); p- Semicarbazide compounds such as toluylenesulfonyl semicarbazide and 4,4′-oxybis (benzenesulfonyl semicarbazide); Triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N, N′-dinitrosopene Methylene terrorism Ramin, N, N'-dimethyl -N, N'N-nitroso compounds such as dinitrosoterephthalamide, and the like.

  The thermal expansion start temperature (foam start temperature) of the foaming agent such as thermally expandable microspheres is not particularly limited, but preferably exceeds 80 ° C. The thermal expansion start temperature of the foaming agent (such as thermally expandable microspheres) is preferably about 85 to 200 ° C. (especially 90 ° C. to 150 ° C.).

  In the present invention, the thermal expansion start temperature (foaming start temperature) of a foaming agent such as a thermally expandable microsphere means a temperature at which the foaming agent starts to expand (foam) by heating. This corresponds to (or corresponds to) the peeling start temperature of the heat-peelable pressure-sensitive adhesive sheet having a heat-expandable pressure-sensitive adhesive layer containing a foaming agent (such as heat-expandable microspheres). As the peeling start temperature of the heat-peelable pressure-sensitive adhesive sheet, for example, by heat treatment, the adhesive force by the heat-expandable pressure-sensitive adhesive layer containing a foaming agent (heat-expandable microspheres, etc.) is 10% or less of the adhesive force before heating. The lowest heat treatment temperature that can be lowered can be obtained. Therefore, the thermal expansion start temperature of the foaming agent (such as thermally expandable microspheres) is the peeling start temperature of the heat-peelable pressure-sensitive adhesive sheet having the thermally expandable adhesive layer containing the foaming agent (such as thermally expandable microspheres), that is, It is obtained by measuring the minimum heat treatment temperature at which the adhesive force by the thermally expandable adhesive layer containing a foaming agent (such as thermally expandable microspheres) can be reduced to 10% or less of the adhesive force before heating. be able to. Specifically, a polyethylene terephthalate film having a width of 20 mm and a thickness of 23 μm on the surface of the heat-expandable pressure-sensitive adhesive layer containing the foaming agent (heat-expandable microspheres, etc.) of the heat-peelable pressure-sensitive adhesive sheet [trade name “Lumirror S10 # 25” (manufactured by Toray Industries, Inc.); sometimes referred to as “PET film”] is bonded with a hand roller so that no air bubbles are mixed, to prepare a test piece. 30 minutes after bonding the PET film to the test piece, the PET film was peeled off at a 180 ° peeling angle, and the adhesive strength at that time (measurement temperature: 23 ° C., tensile speed: 300 mm / min, peeling angle) : 180 °), and the adhesive force is defined as “initial adhesive force”. Moreover, after putting the test piece produced by the said method into the heat circulation type dryer set to each temperature (heat processing temperature) for 1 minute, taking out from a heat circulation type dryer, it is left at 23 degreeC for 2 hours. Then, the PET film is peeled off at a 180 ° peeling angle, and the adhesive strength at that time (measurement temperature: 23 ° C., tensile speed: 300 mm / min, peeling angle: 180 °) is measured. “Adhesive strength after heat treatment”. Then, the lowest heat treatment temperature at which the adhesive strength after the heat treatment is 10% or less of the initial adhesive strength is obtained. This lowest heat treatment temperature can be set as the thermal expansion start temperature of a foaming agent (such as thermally expandable microspheres).

  In order to reduce the adhesive force of the heat-expandable pressure-sensitive adhesive layer efficiently and stably by heat treatment, it has an appropriate strength that does not rupture until the volume expansion coefficient is 5 times or more, especially 7 times or more, particularly 10 times or more. A foaming agent is preferred.

  The blending amount of the foaming agent (such as thermally expandable microspheres) can be appropriately set according to the expansion ratio of the thermally expandable pressure-sensitive adhesive layer or the decrease in adhesive strength, but generally the pressure-sensitive adhesive that forms the heat-expandable pressure-sensitive adhesive layer. The amount is, for example, 1 to 150 parts by weight, preferably 10 to 130 parts by weight, and more preferably 25 to 100 parts by weight with respect to 100 parts by weight of the base polymer.

  When thermally expandable microspheres are used as the foaming agent, the particle size (average particle diameter) of the thermally expandable microspheres can be appropriately selected according to the thickness of the thermally expandable adhesive layer. The average particle diameter of the thermally expandable microspheres can be selected from a range of, for example, 100 μm or less (preferably 80 μm or less, more preferably 1 to 50 μm, particularly 1 to 30 μm). Note that the adjustment of the particle size of the thermally expandable microspheres may be performed in the process of generating the thermally expandable microspheres, or may be performed by means such as classification after the generation.

  Although it will not restrict | limit especially if it has the said characteristic as an adhesive, The thing which does not restrain foaming and / or expansion | swelling of a foaming agent (thermally expansible microsphere etc.) at the time of a heating is preferable. Examples of adhesives include rubber adhesives, acrylic adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, and styrene. -Diene block copolymer-based pressure-sensitive adhesives, and known pressure-sensitive pressure-sensitive adhesives such as those having a melting point of about 200 ° C or less and a melt-meltable resin blended with these pressure-sensitive adhesives (for example, JP-A 56- (See 61468, JP 61-174857, JP 63-17981, JP 56-13040, etc.) Can do. In addition, as the pressure-sensitive adhesive, a radiation curable pressure-sensitive adhesive (or energy beam curable pressure-sensitive adhesive) can be used. These pressure-sensitive adhesives can be used alone or in combination of two or more.

  As the pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive or an acrylic pressure-sensitive adhesive can be preferably used, and an acrylic pressure-sensitive adhesive is particularly preferable. Rubber adhesives include natural rubber and various synthetic rubbers [for example, polyisoprene rubber, styrene / butadiene block copolymer (SB) rubber, styrene / isoprene block copolymer (SI) rubber, styrene / isoprene / styrene. Block copolymer (SIS) rubber, styrene / butadiene / styrene block copolymer (SBS) rubber, styrene / isoprene / butadiene / styrene block copolymer (SIBS) rubber, styrene / ethylene / butylene / styrene block copolymer (SEBS) rubber, styrene / ethylene / propylene / styrene block copolymer (SEPS) rubber, styrene / ethylene / propylene block copolymer (SEP) rubber, recycled rubber, butyl rubber, polyisobutylene, and modified products thereof As the base polymer Include rubber-based adhesives.

The acrylic pressure-sensitive adhesive is an acrylic based on an acrylic polymer (homopolymer or copolymer) using one or more (meth) acrylic acid alkyl esters as monomer components. System adhesives. Examples of the (meth) acrylic acid alkyl ester in the acrylic pressure-sensitive adhesive include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylic. Butyl acid, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ( Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, Undecyl (meth) acrylate, dodecyl (meth) acrylate, (meta Tridecyl acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, (meth) acrylic Examples include (meth) acrylic acid C _1-20 alkyl ester [preferably (meth) acrylic acid C _4-18 alkyl (linear or branched alkyl) ester] such as eicosyl acid.

  The acrylic polymer may be mixed with other monomer components copolymerizable with the (meth) acrylic acid alkyl ester as necessary for the purpose of modifying cohesion, heat resistance, crosslinkability, and the like. Corresponding units may be included. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and carboxyethyl acrylate; acid anhydrides such as maleic anhydride and itaconic anhydride Hydroxyl group-containing monomers such as hydroxy group (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate; styrene sulfonic acid, allyl sulfonic acid, (meth) acrylamide propane sulfonic acid Sulfonic acid group-containing monomers such as sulfopropyl (meth) acrylate; phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl ( (N) (N-substituted) amide monomers such as acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate, N, N-dimethylamino (meth) acrylate (Meth) acrylate aminoalkyl monomers such as ethyl and (meth) acrylate t-butylaminoethyl; (meth) acrylate alkoxyalkyl monomers such as (meth) acrylate methoxyethyl and (meth) acrylate ethoxyethyl Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide Itaconimide monomers such as N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide; N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N -Succinimide monomers such as (meth) acryloyl-8-oxyoctamethylene succinimide; Vinyl ester monomers such as vinyl acetate and vinyl propionate; N-vinyl pyrrolidone, N-methyl vinyl pyrrolidone, N-vinyl pyridine, N-vinyl piperidone N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcarbon Monomers having a nitrogen atom-containing ring such as prolactam; N-vinylcarboxylic amides; styrene monomers such as styrene and α-methylstyrene; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; glycidyl (meth) acrylate Epoxy group-containing acrylic monomers such as; ethylene, propylene, isoprene, butadiene, isobutylene and other olefin monomers; vinyl ether and other vinyl ether monomers; (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol and other glycols Acrylic ester monomers; Monomers with oxygen atom-containing heterocycles such as tetrahydrofurfuryl (meth) acrylate; Fluorine atoms such as fluorine-based (meth) acrylates Acrylic acid ester monomers; Silicone (meth) acrylate and other acrylic acid monomers containing silicon atoms; hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol Di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy Polyfunctional monomers such as acrylate, polyester acrylate, urethane acrylate, divinylbenzene, butyl di (meth) acrylate, hexyl di (meth) acrylate, etc. Is mentioned. These monomer components can be used alone or in combination of two or more.

  In addition to polymer components such as an adhesive component (base polymer), the pressure-sensitive adhesive is a crosslinking agent (for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a melamine-based crosslinking agent, etc.) depending on the type of the pressure-sensitive adhesive. , Tackifiers (for example, rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenol resins, etc., solid, semi-solid or liquid at room temperature), plasticizers, fillers, anti-aging agents, surfactants, etc. These appropriate additives may be included.

  The heat-expandable pressure-sensitive adhesive layer is commonly used to form a sheet-like layer by mixing, for example, a pressure-sensitive adhesive, a foaming agent (such as heat-expandable microspheres), and a solvent or other additive as necessary. This method can be used. Specifically, for example, a mixture containing a pressure-sensitive adhesive, a foaming agent (such as thermally expandable microspheres), and, if necessary, a solvent and other additives is placed on a base material or a rubber-like organic elastic layer described later. By a coating method, a method of coating the mixture on a suitable separator (such as a release paper) to form a thermally expandable adhesive layer, and transferring (transferring) it onto a base material or a rubbery organic elastic layer A heat-expandable adhesive layer can be formed. The thermally expandable pressure-sensitive adhesive layer may be either a single layer or multiple layers.

  The thickness of the heat-expandable pressure-sensitive adhesive layer can be appropriately selected depending on the adhesiveness reduction property, and is, for example, about 5 to 300 μm (preferably 20 to 150 μm). However, when thermally expandable microspheres are used as the foaming agent, the thickness of the thermally expandable pressure-sensitive adhesive layer is preferably thicker than the maximum particle diameter of the contained thermally expandable microspheres. When the thickness of the heat-expandable pressure-sensitive adhesive layer is too thin, the surface smoothness is impaired by the unevenness of the heat-expandable microspheres, and the adhesiveness before heating (unfoamed state) is lowered. In addition, the degree of deformation of the heat-expandable pressure-sensitive adhesive layer by heat treatment is small, and the adhesive force is not easily lowered. On the other hand, if the thickness of the heat-expandable pressure-sensitive adhesive layer is too thick, cohesive failure tends to occur in the heat-expandable pressure-sensitive adhesive layer after foaming by heat treatment.

[Adhesive protective layer]
The adhesive protective layer has a shear elastic modulus at 23 ° C. of 1 × 10 ⁶ Pa or more after curing or drying, and when the thermally expandable adhesive layer is thermally expanded by heat treatment, the thermally expandable adhesive layer It has the structure which can peel at the interface. In particular, the adhesive protective layer has a shear modulus (23 ° C.) of 1 × 10 ⁶ Pa or more (preferably 2 × 10 ⁶ Pa or more) after curing or drying, and a shear modulus (80 ° C.). ) Is preferably 1 × 10 ⁶ Pa or more (preferably 2 × 10 ⁶ Pa or more).

  In addition, the shear elastic modulus described in this specification means the shear storage elastic modulus. Although it does not restrict | limit especially as a measuring method of the shear elastic modulus (shear storage elastic modulus) of an adhesive protective layer, The well-known thru | or usual dynamic viscoelastic characteristic measuring method is employable. Specifically, a trade name “ARES” manufactured by Rheometric Co., Ltd. can be used as the dynamic viscoelasticity measuring apparatus. As measurement conditions, the temperature is 23 ° C. or 80 ° C., the measurement frequency is 1 Hz, the sample thickness (thickness of the adhesive protective layer) is 5 μm, and the strain is 0.1% (23 ° C.). 3% (80 ° C.), plate: conditions of a parallel plate jig having a diameter of 7.9 mmφ can be adopted.

  In addition, the shear elasticity modulus of an adhesive protective layer can be adjusted with the kind of various components which form an adhesive protective layer, its content, etc.

  If the adhesive protective layer has the said characteristic, the material or raw material will not be restrict | limited in particular, However, It is preferable that all are comprised by the organic component. As an adhesive protective layer, it can form with a thermoplastic resin (especially organic type thermoplastic resin), for example. The thermoplastic resin can exhibit adhesive strength by heat, and can exert strong adhesive strength by heating at the time of pasting or after pasting. A thermoplastic resin can be used individually or in combination of 2 or more types.

As such a thermoplastic resin, those having a shear modulus of elasticity of 1 × 10 ⁶ Pa or more (preferably 2 × 10 ⁶ Pa or more) at 23 ° C. after curing or drying can be used. The shear modulus at 23 ° C. after or after drying is 1 × 10 ⁶ Pa or more (preferably 2 × 10 ⁶ Pa or more), and the shear modulus at 80 ° C. is 1 × 10 ⁶ Pa or more (preferably 2 × What becomes 10 ⁶ Pa or more) is suitable.

  Specific examples of the thermoplastic resin for forming the adhesive protective layer include, for example, styrene / butadiene / styrene block copolymer (SBS), styrene / isoprene / butadiene / styrene block copolymer (SIBS), styrene / ethylene / Butylene / styrene block copolymer (SEBS), styrene / ethylene / propylene / styrene block copolymer (SEPS), styrene / ethylene / propylene block copolymer (SEP), styrene / isoprene / styrene block block copolymer (SEP) SIS), styrene block copolymers (SB), styrene block copolymers such as styrene / isoprene block copolymers (SI), and modified resins of styrene block copolymers (for example, modified with maleic acid) Maleic acid modified styrene block Styrene resins such as copolymers, etc .; acrylic resins having at least one selected from (meth) acrylic acid alkyl esters as main monomer components; ethylene-vinyl acetate resins (EVA); olefins such as polypropylene and polyethylene Resin, vinyl acetate resin, polyester, polyamide and the like.

The acrylic resin contains at least one selected from (meth) acrylic acid alkyl esters as a main monomer component, and 1 monomer component that can be copolymerized with (meth) acrylic acid alkyl ester as required. Two or more species are used. Examples of such (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, Isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, (meth) acryl Octyl acid, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, (meth) Undecyl acrylate, dodecyl (meth) acrylate, tridec (meth) acrylate , Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate And (meth) acrylic acid C _1-20 alkyl esters. Examples of the monomer component that can be copolymerized with (meth) acrylic acid alkyl ester include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and carboxyethyl acrylate; Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; Hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; styrene sulfonic acid, Sulfonic acid group-containing monomers such as allyl sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate; phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate; (meth) acrylamide, N (N-substituted) amide monomers such as N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate (Meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid aminoalkyl-based monomers such as t-butylaminoethyl; (meth) acrylic acid methoxyethyl, (meth) acrylic acid ethoxy (Meth) acrylic acid alkoxyalkyl monomers such as ethyl; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; N-methylitaconimide, N-ethylitaconimide, N Itaconic imide monomers such as butyl itaconimide, N-octyl itaconimide, N-2-ethylhexylitaconimide, N-cyclohexitaconimide, N-lauryl itaconimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) Succinimide monomers such as acryloyl-6-oxyhexamethylene succinimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide; vinyl ester monomers such as vinyl acetate and vinyl propionate; N-vinylpyrrolidone and N-methylvinyl Pyrrolidone, N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinyl Monomers having a nitrogen atom-containing ring such as luxazole, N-vinylmorpholine, N-vinylcaprolactam; N-vinylcarboxylic acid amides; styrene monomers such as styrene and α-methylstyrene; cyano such as acrylonitrile and methacrylonitrile Acrylate monomers; Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; Olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; Vinyl ether monomers such as vinyl ether; Polyethylene glycol (meth) acrylate, ( Glycol-based acrylic ester monomers such as (meth) acrylic acid polypropylene glycol; monomers having an oxygen atom-containing heterocyclic ring such as (meth) acrylic acid tetrahydrofurfuryl; Acrylic acid ester monomers containing fluorine atoms such as silicon (meth) acrylates; Acrylic acid ester monomers containing silicon atoms such as silicone (meth) acrylates; Hexanediol di (meth) acrylates, (poly) Ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) ) Acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, divinylbenzene, butyl di (meth) acrylate, f And polyfunctional monomers such as xyldi (meth) acrylate.

  As the thermoplastic resin forming the adhesive protective layer, styrene resins such as styrene block copolymers or modified resins thereof (for example, maleic acid modified styrene block copolymers) and various acrylic resins are suitable. Can be used.

  Such a thermoplastic resin may have a crosslinkable structure. For example, in the case of a styrene resin, a crosslinkable structure can be obtained by modification with maleic acid or the like. Moreover, in the case of acrylic resin, it can be set as the structure which can be bridge | crosslinked by using a functional group containing monomer (For example, a carboxyl group containing monomer, a hydroxyl group containing monomer, etc.) as a monomer component.

  Therefore, the adhesive protective layer may be formed of a crosslinked structure of a thermoplastic resin. In addition, when crosslinking a thermoplastic resin, various crosslinking agents can be used. Such a crosslinking agent is not particularly limited, and can be appropriately selected according to the type of thermoplastic resin. For example, an epoxy such as polyethylene glycol diglycidyl ether, diglycidyl ether, trimethylolpropane triglycidyl ether, etc. Cross-linking agents; isocyanate-based cross-linking agents such as tolylene diisocyanate, trimethylolpropane triisocyanate, diphenylmethane diisocyanate; melamine-based cross-linking agents such as alkyl etherified melamine compounds; metal salt-based cross-linking agents; metal chelate-based cross-linking agents; Agents: peroxide crosslinking agents; coupling agent crosslinking agents such as silane coupling agents can be used.

  In the adhesive protective layer, in addition to the thermoplastic resin and the crosslinking agent, various additives can be appropriately selected and blended as necessary. Examples of such additives include tackifiers (rosin derivative resins, polyterpene resins, petroleum resins, phenol resins, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, colorants (pigments, dyes, etc.), Examples thereof include a plasticizer, a filler, and a surfactant.

  In addition, since it is preferable that the adhesive protective layer is composed entirely of organic components as described above, additives such as crosslinking agents and tackifiers are composed of organic components (organic crosslinking agents, organic It is preferable to use a tackifying resin. In addition, as will be described later, when a foaming agent (such as a thermally expandable microsphere) is included in the adhesive protective layer, an organic thermal expandable microsphere may be used as the foaming agent (such as a thermally expandable microsphere). Can be suitably used.

  The adhesive protective layer may contain a foaming agent. When a foaming agent is contained in the adhesive protective layer, when the thermally expandable adhesive layer is thermally expanded by heat treatment, the adhesive protective layer can also be thermally expanded. It can be more easily peeled off at the interface between the adhesive layer and the adhesive protective layer. As such a foaming agent, it can be used by appropriately selecting from the foaming agents exemplified in the section of the thermally expandable pressure-sensitive adhesive layer (such as thermally expandable microspheres).

  Foaming agents (such as thermally expandable microspheres) used in the adhesive protective layer and foaming agents (such as thermally expandable microspheres) used in the thermally expandable adhesive layer are foaming agents having different thermal expansion start temperatures. Although it may exist, it is preferable that it is a foaming agent which has the same or approximate thermal expansion start temperature. Note that the foaming agent used in the adhesive protective layer and the foaming agent used in the thermally expandable adhesive layer may be the same foaming agent or different foaming agents.

  The adhesive protective layer can be formed, for example, by a conventional method of forming a sheet-like layer by mixing a thermoplastic resin and, if necessary, a solvent or other additives. Specifically, for example, a mixture containing a thermoplastic resin and, if necessary, a solvent and other additives is applied to an appropriate separator (such as release paper) to form the adhesive protective layer. The pressure-sensitive adhesive protective layer can be formed on the heat-expandable pressure-sensitive adhesive layer by a method of transferring (transferring) it onto the heat-expandable pressure-sensitive adhesive layer. The adhesive protective layer may be either a single layer or multiple layers.

  The thickness of the adhesive protective layer is, for example, 0.05 to 100 μm (preferably 0.2 to 50 μm, more preferably 0.5 to 20 μm). If the thickness of the adhesive protective layer is too thin, the strength may not be sufficient and deformation may occur. On the other hand, if the thickness of the pressure-sensitive protective layer is too thick, it takes time to remove the pressure-sensitive protective layer in the firing step, and workability is reduced.

[Separator]
In FIG. 1, a separator (release liner) is used as a protective material for the adhesive protective layer, but the separator is not necessarily provided. In addition, when the adhesive layer is formed also in the back side of a base material, the separator (release liner) may be used also as a protective material of the adhesive layer. The separator is peeled off when the heat-peelable pressure-sensitive adhesive sheet is attached to the adherend. A conventional release paper or the like can be used as such a separator. Specifically, as the separator, for example, a release layer such as a plastic film or paper surface-treated with a release agent such as a silicone release agent, a long-chain alkyl release agent, a fluorine release agent, or a molybdenum sulfide release agent. Fluoropolymers such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, chlorofluoroethylene / vinylidene fluoride copolymer A low-adhesive base material made of a nonpolar polymer such as an olefin resin (for example, polyethylene, polypropylene, etc.) can be used. In addition, a separator can also be used as a base material for supporting a heat-expandable adhesive layer.

  The separator can be formed by a known or common method. Further, the thickness of the separator is not particularly limited.

[Other layers]
As a heat-peelable pressure-sensitive adhesive sheet, it is sufficient that a heat-expandable pressure-sensitive adhesive layer and an adhesive protective layer are formed in this order on at least one surface of the base material. For example, (1) thermal expansion on one side of the base material Heat-peelable pressure-sensitive adhesive sheet in the form in which the adhesive pressure-sensitive adhesive layer and the adhesive protective layer are formed in this order, (2) a heat-expandable pressure-sensitive adhesive layer is formed on both surfaces of the substrate, of the two heat-expandable pressure-sensitive adhesive layers A heat-peelable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed on at least one heat-expandable pressure-sensitive adhesive layer, and (3) a heat-expandable pressure-sensitive adhesive layer and a pressure-sensitive protective layer on one surface of the substrate. Examples thereof include a heat-peelable pressure-sensitive adhesive sheet formed in this order and having a non-thermally expandable pressure-sensitive adhesive layer (a pressure-sensitive adhesive layer not having heat expandability) formed on the other surface.

  Moreover, the heat-peelable pressure-sensitive adhesive sheet may have one or two or more intermediate layers between the base material and the heat-expandable pressure-sensitive adhesive layer. Examples of such an intermediate layer include a release agent coating layer for the purpose of imparting releasability and a primer coating layer for the purpose of improving adhesion. In addition, as an intermediate layer other than the coating layer of the release agent and the coating layer of the primer, for example, a layer for the purpose of imparting good deformability, the purpose of increasing the adhesion area to the adherend (semiconductor wafer, etc.) The purpose is to improve the processability of reducing the adhesive force by heating, the layer aiming to improve the surface shape of the adherend (semiconductor wafer, etc.) And a layer intended to improve releasability from an adherend (such as a semiconductor wafer) after heating.

  In particular, a rubbery organic elastic layer may be provided as an intermediate layer between the base material and the thermally expandable pressure-sensitive adhesive layer from the viewpoint of imparting deformability of the heat-peelable pressure-sensitive adhesive sheet and improving peelability after heating. it can. Thus, by providing the rubber-like organic elastic layer, when the heat-peelable pressure-sensitive adhesive sheet is bonded to the adherend, the surface of the heat-peelable pressure-sensitive adhesive sheet (the surface of the adhesive protective layer) is adhered The surface area can be satisfactorily followed to increase the adhesion area, and when the heat-peelable pressure-sensitive adhesive sheet is heat-peeled from the adherend, the heat-expandable pressure-sensitive adhesive layer is highly expanded (accuracy). Well) can control and expand the heat-expandable adhesive layer preferentially and uniformly in the thickness direction. The rubber-like organic elastic layer is a layer provided as necessary, and is not necessarily provided.

  The rubbery organic elastic layer is preferably provided on the base-side surface of the thermally expandable adhesive layer in a form superimposed on the thermally expandable adhesive layer. In addition, it can provide also as layers other than the intermediate | middle layer between a base material and a thermally expansible adhesive layer. The rubbery organic elastic layer can be interposed on one side or both sides of the substrate.

  The rubbery organic elastic layer is preferably formed of, for example, natural rubber, synthetic rubber, or synthetic resin having rubber elasticity having a D-type Sure D-type hardness of 50 or less (particularly 40 or less) based on ASTM D-2240. Examples of the synthetic rubber or the synthetic resin having rubber elasticity include nitrile-based, diene-based, and acrylic-based synthetic rubbers; polyolefin-based and polyester-based thermoplastic elastomers; ethylene-vinyl acetate copolymer, polyurethane, polybutadiene, and the like. And a synthetic resin having rubber elasticity such as soft polyvinyl chloride. Even if it is essentially a hard polymer such as polyvinyl chloride, rubber elasticity can be manifested in combination with compounding agents such as plasticizers and softeners. Such a composition can also be used as a constituent material of the rubbery organic elastic layer. In addition, the pressure-sensitive adhesive constituting the heat-expandable pressure-sensitive adhesive layer (for example, rubber pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, vinyl alkyl ether pressure-sensitive adhesive, silicone pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, polyamide-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive) Adhesives such as adhesives, fluorine-based adhesives, styrene-diene block copolymer-based adhesives, and adhesives with improved melting characteristics in which a melting point of about 200 ° C. or less is blended with these adhesives. Substances can also be used as a constituent material of the rubbery organic elastic layer.

  The rubber-like organic elastic layer is, for example, a method in which a coating liquid containing a rubber-like organic elastic layer forming material such as natural rubber, synthetic rubber or synthetic resin having rubber elasticity is applied on a substrate (coating method), the rubber A method of adhering a film made of a layered organic elastic layer forming material or a laminated film in which a layer made of the rubbery organic elastic layer forming material is previously formed on one or more thermally expandable pressure-sensitive adhesive layers (dry laminating method) ), A resin composition containing the constituent material of the substrate and a resin composition containing the rubber-like organic elastic layer forming material can be formed by a forming method such as a method (coextrusion method).

  The thickness of the rubbery organic elastic layer is, for example, about 5 to 300 μm (preferably 20 to 150 μm). If the thickness of the rubbery organic elastic layer is too thin, a three-dimensional structural change after heating and foaming cannot be formed, and the peelability may deteriorate. The rubbery organic elastic layer may be a single layer or may be composed of two or more layers.

  The rubbery organic elastic layer may be formed of an adhesive substance mainly composed of natural rubber, synthetic rubber, or synthetic resin having rubber elasticity, and is formed of a foam film or the like mainly composed of such a component. May be. Foaming is a conventional method, for example, a method using mechanical stirring, a method using a reaction product gas, a method using a foaming agent, a method for removing soluble substances, a method using a spray, a method for forming a syntactic foam, It can be performed by a sintering method or the like.

  Moreover, as a rubber-like organic elastic layer, when using a radiation curable substance for a thermally expansible adhesive layer etc., it is preferable to use what does not inhibit radiation permeation | transmission.

  The heat-peelable pressure-sensitive adhesive sheet of the present invention may have the form of a double-sided adhesive sheet whose both surfaces are adhesive surfaces, but has the form of an adhesive sheet whose only one surface is an adhesive surface. It is preferable. Therefore, the heat-peelable pressure-sensitive adhesive sheet is preferably a heat-peelable pressure-sensitive adhesive sheet in which a thermally expandable pressure-sensitive adhesive layer and a pressure-sensitive adhesive protective layer are formed in this order on one surface of the substrate.

  Moreover, the heat-peelable pressure-sensitive adhesive sheet may be formed in a form wound in a roll shape, or may be formed in a form in which sheets are laminated. For example, when it has a form wound in a roll shape, the adhesive protective layer formed on the thermally expandable adhesive layer is wound in a roll shape in a state protected by a separator, that is, a base A material, a thermally expandable adhesive layer formed on one surface of the substrate, an adhesive protective layer formed on the thermally expandable adhesive layer, and a separator formed on the adhesive protective layer If necessary, a heat-peelable pressure-sensitive adhesive sheet (heat-peelable pressure-sensitive adhesive) wound in a roll or wound in a state constituted by an intermediate layer (such as a rubbery organic elastic layer) Tape).

  In addition, as a heat-peelable pressure-sensitive adhesive sheet (heat-peelable pressure-sensitive adhesive tape) in a state wound or rolled, a separator is not used, and a peelable treatment layer (back treatment layer) is provided on the back surface of the substrate. You may have the structure formed.

  Thus, the heat-peelable pressure-sensitive adhesive sheet can have a form such as a sheet form or a tape form.

Since the heat-peelable pressure-sensitive adhesive sheet of the present invention has the above-described configuration [that is, the shear elastic modulus (23 ° C.) is 1 × 10 ⁶ Pa or more and the heat-expandable pressure-sensitive adhesive layer on the heat-expandable pressure-sensitive adhesive layer. Since it has a structure having an adhesive protective layer that can be peeled off at the interface with the thermally expandable adhesive layer when the layer is thermally expanded by heat treatment], during the processing of the adherend including the pressurizing step In addition, deformation of the adherend due to pressurization in the pressurization process is prevented, and it is possible to exhibit excellent adhesiveness in the lamination process and cutting process. Can be peeled off. Therefore, it is possible to exhibit viscoelasticity and adhesive strength suitable for fixing during processing of the adherend, and when the adhesive state is desired to be released after achieving the adhesive purpose, the adhesive strength is reduced by heating. The adherend can be easily peeled or separated. Thus, the heat-peelable pressure-sensitive adhesive sheet of the present invention can be suitably used as a heat-peelable pressure-sensitive adhesive sheet used when processing an adherend in a process including a pressurizing process. The heat-peelable pressure-sensitive adhesive sheet can also be used as a protective material when conveying the adherend.

[Processing method of adherend]
In the method for processing an adherend (workpiece) according to the present invention, the adherend is bonded onto the adhesive protective layer in the heat-peelable pressure-sensitive adhesive sheet, and the adherend is subjected to a processing treatment. I am processing my body. The process for processing the adherend can be arbitrarily selected, and may include a pressurizing process (pressing and pressing process). More specifically, the processes for processing the adherend include an electrode printing process (pattern formation process, etc.), a lamination process, a pressurizing process (pressing press process), and a cutting process (polishing) on the green sheet. Treatment process, dicing process, etc.), firing process and the like, and in addition, an assembly process and the like.

  In the processing of such an adherend, in the pressurizing step, the adhesive protective layer is required to have a high shear elastic modulus. Therefore, the adhesive protective layer is heated at a temperature at which the adhesive protective layer exhibits a high shear elastic modulus. It is important to perform the pressing step.

  And after processing a to-be-adhered body (especially after achieving the adhesion objective, or when you want to release an adhesion state), it heats to the temperature more than the foaming start temperature of the foaming agent in a thermally expansible adhesive layer. Thus, the adherence (processed product) subjected to the processing treatment can be isolated by reducing the adhesive force and peeling or separating the adherend subjected to the processing treatment.

  In addition, as a heat treatment method at the time of peeling or separating the adherend (processed product) subjected to the processing treatment, for example, an appropriate heating means such as a hot plate, a hot air dryer, a near infrared lamp, an air dryer, or the like is used. It can be done using it. The heating temperature may be equal to or higher than the thermal expansion start temperature (foaming start temperature) of the foaming agent (thermally expandable microspheres, etc.) in the heat-expandable adhesive layer, but the heat treatment conditions are the surface condition of the adherend. It can be set as appropriate depending on the reduction of the adhesion area due to the type of foaming agent (thermally expandable microspheres, etc.), the heat resistance of the substrate or adherend, the heating method (heat capacity, heating means, etc.), and the like. General heat treatment conditions are a temperature of 100 to 250 ° C. and a time of 1 to 90 seconds (hot plate or the like) or 5 to 15 minutes (hot air dryer or the like). Note that the heat treatment can be performed at an appropriate stage depending on the purpose of use. In some cases, an infrared lamp or heated water can be used as the heating source.

  In addition, as a method of peeling or separating the adherend (processed product) that has been subjected to the processing treatment by heat treatment, a method using a heating press method can also be used. In this hot press method, a hot press plate or a hot press apparatus having a hot press roll can be used. Specifically, the adherend can be peeled off or separated by heating by being sandwiched by a hot press plate or a hot press roll. When using a heating press plate, the heating press plates on both sides in the heating press apparatus may be heated simultaneously, or only one heating press plate may be heated. Moreover, when using a heating press roll, the heating press roll of both sides may be heated simultaneously, and only the heating press roll of one side may be heated.

  As described above, when the adherend (processed product) is peeled off or separated by heat treatment, the adhesive protective layer is transferred to the adherend. Can be easily burned off.

[Adherent]
The article to be adhered and held by the heat-peelable pressure-sensitive adhesive sheet (adhered body; article to be processed) can be arbitrarily selected. Specifically, the adherend includes electronic parts such as semiconductor wafers (silicon wafers) and semiconductor chips; electrical articles such as ceramic capacitors and oscillators; display devices such as liquid crystal cells, Various articles such as a thermal head, a solar cell, a printed circuit board (such as a multilayer ceramic sheet), and a so-called “green sheet” can be mentioned. An adherend may be individual or may be combined 2 or more types.

  Such an adherend (particularly, printed circuit board) processing step includes a baking step after a pressing step, a laminating step, a cutting step, and the like.

[Processed adherend]
In the present invention, various processed products (processed adherends) can be obtained by pasting an adherend (processed product) to the heat-peelable pressure-sensitive adhesive sheet and then performing a processing treatment. For example, when an electronic component such as a semiconductor wafer is used as the adherend (processed product), an electronic component, a circuit board, or the like can be obtained as the processed product. That is, the electronic component and circuit board of the present invention are manufactured using the heat-peelable pressure-sensitive adhesive sheet, and are manufactured using the method for processing the adherend.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(Example 1)
For 100 parts by weight of acrylic copolymer (acrylic copolymer having butyl acrylate: 100 parts by weight, ethyl acrylate: 30 parts by weight, 2-hydroxyethyl acrylate: 5 parts by weight as a monomer component), Isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 1 part by weight and a resin composition (mixture) containing toluene as a solvent, so that the thickness after drying is 15 μm. It was applied on a polyester film (thickness: 100 μm) as a material and dried to form a rubbery organic elastic layer.

  Next, for 100 parts by weight of acrylic copolymer (acrylic copolymer having butyl acrylate: 100 parts by weight, ethyl acrylate: 30 parts by weight, 2-hydroxyethyl acrylate: 5 parts by weight as a monomer component) As the thermally expandable microsphere, the trade name “Matsumoto Microsphere F-501D” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd .; average particle size: 13 μm): 50 parts by weight and an isocyanate-based crosslinking agent (trade name “Coronate L”) “Nippon Polyurethane Industry Co., Ltd.”: 1 part by weight and a resin composition (mixture) containing toluene as a solvent was applied on a separator so that the thickness after drying was 35 μm, dried and thermally expanded. An adhesive layer was formed. Thereafter, the heat-expandable adhesive layer is bonded to the rubber-like organic elastic layer, and a sheet having a layer structure of base material / rubber-like organic elastic layer / heat-expandable adhesive layer / separator (“before protection” Sheet A ”may be referred to).

Also, maleic acid-modified styrene / ethylene / butylene / styrene block copolymer [SEBS; styrene moiety / ethylene / butylene moiety (weight ratio) = 30/70, acid value: 10 (mg-CH ₃ ONa / g)]: 3 parts by weight of epoxy-based cross-linking agent (trade name “TETRAD-C” manufactured by Mitsubishi Gas Chemical Company) and 100 parts by weight of terpene phenol resin (trade name “Mighty Ace G125” manufactured by Yasuhara Chemical Co., Ltd.): 10 parts by weight As a thermally expandable microsphere, a resin composition (Matsumoto Microsphere F-501D) (manufactured by Matsumoto Yushi Seiyaku Co., Ltd .; average particle size: 13 μm): 50 parts by weight and toluene as a solvent ( The mixture was applied onto the separator so that the thickness after drying was 5 μm, and dried to form an adhesive protective layer. Then, after peeling the separator from the pre-protection sheet A, the adhesive protective layer was bonded to the thermally expandable adhesive layer, and the base material / rubbery organic elastic layer / thermally expandable adhesive layer / adhesive protective layer / A heat-peelable pressure-sensitive adhesive sheet having a separator layer structure was obtained.

(Example 2)
To 100 parts by weight of an acrylic copolymer (acrylic copolymer having 2-ethylhexyl acrylate: 30 parts by weight, ethyl acrylate: 70 parts by weight, acrylic acid: 5 parts by weight as a monomer component), epoxy type Cross-linking agent (trade name “TETRAD-C” manufactured by Mitsubishi Gas Chemical Co., Inc.): 1 part by weight of a resin composition (mixture) containing toluene as a solvent so that the thickness after drying is 10 μm. Was coated on a polyester film (thickness: 100 μm) and dried to form a rubbery organic elastic layer.

  Next, with respect to 100 parts by weight of an acrylic copolymer (acrylic copolymer having 2-ethylhexyl acrylate: 30 parts by weight, ethyl acrylate: 70 parts by weight, acrylic acid: 5 parts by weight as a monomer component), As the thermally expandable microspheres, the trade name “Matsumoto Microsphere F-501D” (Matsumoto Yushi Seiyaku Co., Ltd .; average particle size: 13 μm): 50 parts by weight and an epoxy crosslinking agent (trade name “TETRAD-C”) (Mitsubishi Gas Chemical Co., Ltd.): A resin composition (mixture) containing 4 parts by weight and toluene as a solvent is applied on the separator so that the thickness after drying is 35 μm, and dried to thermally expand. An adhesive layer was formed. Thereafter, the heat-expandable adhesive layer is bonded to the rubber-like organic elastic layer, and a sheet having a layer structure of base material / rubber-like organic elastic layer / heat-expandable adhesive layer / separator (“before protection” In some cases, it is referred to as “Sheet B”.

  In addition, acrylic copolymer (ethyl acrylate: 100 parts by weight, acrylic acid 2-hydroxyethyl: 5 parts by weight, methyl methacrylate: 30 parts by weight, vinyl acetate: 30 parts by weight of acrylic copolymer Combined) 100 parts by weight of isocyanate crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 4 parts by weight and alkylphenol resin (trade name “Tamanol 100S” manufactured by Arakawa Chemical Co., Inc .; tackifying resin) : 10 parts by weight and, as thermally expandable microspheres, trade name “Matsumoto Microsphere F-501D” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd .; average particle size: 13 μm): 50 parts by weight and toluene as a solvent The resin composition (mixture) was applied onto the separator so that the thickness after drying was 5 μm, and dried to form an adhesive protective layer. Then, after peeling the separator from the pre-protection sheet B, the adhesive protective layer was bonded to the thermally expandable adhesive layer, and the base material / rubbery organic elastic layer / thermally expandable adhesive layer / adhesive protective layer / A heat-peelable pressure-sensitive adhesive sheet having a separator layer structure was obtained.

(Comparative Example 1)
A heat-peelable pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the adhesive protective layer was not provided. That is, the heat-peelable pressure-sensitive adhesive sheet has a layer structure of base material / rubber-like organic elastic layer / thermally expandable pressure-sensitive adhesive layer / separator, and corresponds to the pre-protection sheet A.

(Comparative Example 2)
A heat-peelable pressure-sensitive adhesive sheet was produced in the same manner as in Example 2 except that the adhesive protective layer was not provided. That is, the heat-peelable pressure-sensitive adhesive sheet has a layer structure of base material / rubber-like organic elastic layer / thermally expandable pressure-sensitive adhesive layer / separator, and corresponds to the pre-protection sheet B.

(Evaluation)
About the heat-peelable pressure-sensitive adhesive sheets obtained in Examples 1 and 2 and Comparative Examples 1 and 2, the shear modulus, adhesiveness, heat-peelable property, and thermal expansion pressure-sensitive adhesive layer are shifted by the following measurement method or evaluation method. Evaluated. The evaluation results are shown in Table 1.

(Measurement method of shear modulus)
The shear modulus was measured for the adhesive protective layer on the separator before the adhesive protective layer on the separator was bonded to the thermally expandable adhesive layer. Specifically, the adhesive protective layer on the separator is peeled off from the separator, and the adhesive protective layer is set in a predetermined part of a product name “ARES” manufactured by Rheometric as a dynamic viscoelasticity measuring device. Temperature: 23 ° C. or 80 ° C., measurement frequency: 1 Hz, sample thickness (thickness of adhesive protective layer): 5 μm, strain: 0.1% (23 ° C.) or 0.3% (80 ° C.), Plate: The shear elastic modulus (Pa) of the adhesive protective layer was measured under the conditions of a parallel plate jig having a diameter of 7.9 mmφ.

(Adhesion evaluation method)
After the heat-peelable pressure-sensitive adhesive sheet is cut to a width of 20 mm and the separator is peeled off, a polyethylene terephthalate sheet as an adherend is pasted on the adhesive protective layer (Example) or the heat-expandable adhesive layer (Comparative Example). Then, it was heated at 80 ° C. for 1 minute and cooled at room temperature (about 20 to 25 ° C.). Thereafter, the load when the polyethylene terephthalate sheet was peeled off was measured under the conditions of a peeling rate of 300 mm / min and 23 ° C., and 180 ° peel adhesive strength (N / 20 mm) was measured.

(Evaluation method of heat peelability)
After the heat-peelable pressure-sensitive adhesive sheet is cut into a width of 20 mm and the separator is peeled off, on the adhesive protective layer (Examples 1 and 2) or the thermally expandable pressure-sensitive adhesive layer (Comparative Examples 1 and 2), A polyethylene terephthalate sheet was affixed, then heated at 80 ° C. for 1 minute, and cooled at room temperature (about 20 to 25 ° C.). Then, it heated at 130 degreeC for 1 minute, the peeling condition of the sheet | seat made from a polyethylene terephthalate was confirmed visually, and heat peelability was evaluated by the following reference | standard.
Evaluation criteria ○: Peeled at the interface between the thermally expandable adhesive layer and the adhesive protective layer (Examples 1 and 2) or the polyethylene terephthalate sheet (Comparative Examples 1 and 2).

(Evaluation method for misalignment of thermally expandable adhesive layer)
The heat-release type pressure-sensitive adhesive sheet (surface area: 2 cm ² ) was subjected to a press press for 3 seconds at room temperature and pressure: 3 MPa for a total of 100 times, and then the distance of protrusion (displacement) of the glue (adhesive component) was determined. Measurement was made and the deviation of the thermally expandable adhesive layer was evaluated according to the following criteria. As the protrusion distance, an average value of the maximum protrusion amounts of the four sides was adopted.
Evaluation criteria ○: The protruding distance is 0.02 mm or less. ×: The protruding distance exceeds 0.02 mm.

  As is clear from Table 1, the heat-peelable pressure-sensitive adhesive sheets according to Examples 1 and 2 have a pressure-sensitive adhesive layer formed on the heat-expandable pressure-sensitive adhesive layer, and the pressure-sensitive adhesive protective layer has a shear elastic modulus at room temperature. Since it has an appropriate size and a good shear modulus at 80 ° C., it can effectively exhibit excellent elastic force and adhesive force. Specifically, the thermal expansion adhesive layer is hardly displaced even by a press at room temperature. Of course, the adherend (or processed product) can be easily peeled off by heating.

  Therefore, when the adherend is processed using the heat-peelable pressure-sensitive adhesive sheets according to Examples 1 and 2 corresponding to the present invention, productivity due to improved component accuracy, reduced size, and improved yield prevention Can be effectively improved.

It is a schematic sectional drawing which shows partially an example of the heat peeling type adhesive sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat peeling type adhesive sheet 2 Base material 3 Thermally expansible adhesive layer 4 Adhesive protective layer 5 Rubber-like organic elastic layer 6 Separator

Claims (9)

A heat-peelable pressure-sensitive adhesive sheet in which a heat-expandable pressure-sensitive adhesive layer containing a foaming agent is formed on at least one surface of a substrate, and the surface of the heat-expandable pressure-sensitive adhesive layer has a shear modulus of 1 × 10 at 23 ° C. Heating characterized by having an adhesive protective layer that is ⁶ Pa or more and can be peeled off at the interface with the thermally expandable adhesive layer when the thermally expandable adhesive layer is thermally expanded by heat treatment Peelable adhesive sheet. The heat-peelable pressure-sensitive adhesive sheet according to claim 1, wherein the adhesive protective layer further has a shear elastic modulus at 80 ° C. of 1 × 10 ⁶ Pa or more. The heat-peelable pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the adhesive protective layer is entirely composed of an organic component. The heat-peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the adhesive protective layer has a thickness of 0.05 to 100 µm. A method for processing an adherend using a heat-peelable pressure-sensitive adhesive sheet, wherein the adherend is bonded onto the adhesive protective layer of the heat-peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 4. A method for processing an adherend, wherein the adherend is processed by processing the adherend. The method for processing an adherend according to claim 5, wherein the adherend is an electronic component. The method for processing an adherend according to claim 5, wherein the adherend is a green sheet for a ceramic capacitor and has a green sheet laminating step. An electronic component manufactured using the method for processing an adherend according to claim 6. A multilayer ceramic capacitor manufactured by using the method for processing an adherend according to claim 7.

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