JP2013100451A - Thermal delamination type sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal delamination type sheet excellent in durability at high temperatures.SOLUTION: This thermal delamination type sheet has a thermal curing rate of 80% or more. Moreover the thermal delamination type sheet includes a polyimide resin, where imidation rate thereof is 80% or more.

Description

  The present invention relates to a heat-peelable sheet.

  Conventionally, in the manufacturing and processing processes of electronic parts, etc., temporary fixing of various materials, surface protection of metal plates, etc. has been performed, and sheet members used for such applications are covered after the purpose of use is finished. It is required that it can be easily peeled and removed from the adherend. Conventionally, a heat-sensitive adhesive that can be peeled off by heat treatment has been disclosed as such a sheet member (see, for example, Patent Document 1). Patent Document 1 describes that the heat-sensitive adhesive can be used at a temperature up to 180 ° C.

US Pat. No. 7,202,107

  In recent years, there has been a strong demand for heat-peelable sheets that do not deteriorate even at higher temperatures. This invention is made | formed in view of the subject mentioned above, The objective is to provide the heat-peelable sheet | seat which is excellent in durability at high temperature.

  The present inventors have found that the above problems can be solved by adopting the following configuration, and have completed the present invention.

  That is, the heat-peelable sheet according to the present invention has a heat curing rate of 80% or more.

  The heat-peelable sheet according to the present invention has a heat curing rate of 80% or more. Therefore, when used in a high temperature environment, further thermosetting hardly occurs. As a result, it is excellent in durability at high temperatures. The thermosetting rate is obtained by measuring the calorific value using DSC (differential scanning calorimetry). A specific method will be described in detail later.

  Moreover, the heat peelable sheet | seat which concerns on this invention contains a polyimide resin, and imidation ratio is 80% or more. Therefore, further imidization hardly occurs when used in a high temperature environment. As a result, it is excellent in durability at high temperatures. The imidation ratio is determined by measuring the peak intensity of the imide group using 1H-NMR (proton nuclear magnetic resonance). A specific method will be described in detail later.

  According to the present invention, it is possible to provide a heat-peelable sheet that is excellent in durability at high temperatures.

  The heat-peelable sheet according to the present invention has (a) a thermosetting rate of 80% or more, or (b) contains a polyimide resin and has an imidization rate of 80% or more.

  In the case of (a), the heat-peelable sheet according to the present invention has a thermosetting rate of 80% or more, preferably 90% or more, and more preferably 95% or more. Moreover, as an upper limit of the said thermosetting rate of the said heat release type | mold sheet, it is so preferable that it is large, and 100% and 99.9% can be mentioned. Since the thermosetting rate of the heat-peelable sheet is 80% or more (for example, 80 to 100%), further thermosetting hardly occurs when used in a high temperature environment. As a result, it is excellent in durability at high temperatures. In the present invention, “heat-cured” means that the resin constituting the heat-peelable sheet is cured by causing a chemical reaction by heat and generating a three-dimensional cross-linking between molecules. Does not include degradation or decomposition due to oxidation.

The thermosetting rate is obtained by measuring the calorific value using DSC (differential scanning calorimetry). Specifically, a heating rate is applied from room temperature (23 ° C.) using a state in which a solution for manufacturing a heat-peelable sheet (polyamic acid-containing solution) is applied and dried (condition: 120 ° C. for 10 minutes). The calorific value (total calorific value) when the temperature is raised to 500 ° C. (the temperature at which the thermosetting reaction is assumed to be completely completed) is measured at 10 ° C./min. In addition, after applying a solution for manufacturing a heat-peelable sheet and drying it, a heat-peelable sheet manufactured by predetermined heating is used, and the temperature rising rate is 10 ° C / min from room temperature (23 ° C). Under these conditions, the calorific value when the temperature is raised to 500 ° C. (the temperature at which the thermosetting reaction is completely completed) is measured. Thereafter, the following formula (1) is obtained.
Formula (1):
[1-((Amount of heat generated after manufacturing the heat-peelable sheet) / (Total amount of heat generated))] × 100 (%)
As the exotherm, the reaction exotherm in the temperature range of ± 5 ° C. of the reaction exothermic peak temperature measured with a differential scanning calorimeter is used.

  The heat-peelable sheet is not particularly limited as long as the heat curing rate is 80% or more, but polyimide resin, silicone resin, acrylic resin, fluororesin, epoxy resin, urethane resin, rubber resin, etc. Can be mentioned.

  The heat-peelable sheet according to (b) contains a polyimide resin and has an imidization rate of 80% or more. The heat-peelable sheet may contain a polyimide resin. That is, the heat-peelable sheet may contain a resin other than the polyimide resin, or may be composed only of the polyimide resin. When the heat-peelable sheet contains a polyimide resin or consists only of a polyimide resin, the imidization rate is 80% or more, preferably 90% or more, and more preferably 95% or more. preferable. The imidation ratio of the heat-peelable sheet is more preferably 98% or more (particularly 99% or more). Moreover, as an upper limit of the imidation rate of the said heat peelable sheet | seat, it is so preferable that it is large, and 100% and 99.9% can be mentioned. When the imidation ratio of the heat-peelable sheet is 80% or more (for example, 80 to 100%), further imidization hardly occurs when used in a high temperature environment. As a result, it is excellent in durability at high temperatures.

The imidization ratio is determined by measuring the peak intensity of the imide group using 1H-NMR (proton nuclear magnetic resonance, manufactured by JEOL Ltd., LA400). Specifically, a solution for producing a heat-peelable sheet (solution containing polyamic acid) is applied and dried (drying conditions: 50-150 ° C. for 5-30 minutes), and imidized (imidation conditions: 200- (1-5 hours at 450 ° C.). In this state, the peak area A derived from the OR proton (the peak area derived from the OR proton when the polyamic acid diamine and acid anhydride are not closed) and the imide group NR proton derived The peak area B (peak area derived from N—R protons when the diamine and acid anhydride of the polyamic acid are in a closed state) was determined, and the imidization ratio (%) was determined from the formula (2).
Formula (2):
[(B) / (A + B)] × 100 (%)

  Hereinafter, unless otherwise specified, both the heat-peelable sheet according to (a) and the heat-peelable sheet according to (b) will be described.

  The polyimide resin can be generally obtained by imidizing (dehydrating and condensing) a polyamic acid that is a precursor thereof. As a method for imidizing the polyamic acid, for example, a conventionally known heat imidization method, azeotropic dehydration method, chemical imidization method and the like can be employed. Of these, the heating imidization method is preferable. When the heat imidization method is employed, it is preferable to perform heat treatment under a nitrogen atmosphere or an inert atmosphere such as a vacuum in order to prevent deterioration of the polyimide resin due to oxidation.

  The polyamic acid can be obtained by charging and reacting an acid anhydride and a diamine so as to have a substantially equimolar ratio in an appropriately selected solvent.

The polyimide resin preferably has a structural unit derived from a diamine having an ether structure. The diamine having an ether structure is not particularly limited as long as it is a compound having an ether structure and having at least two terminals having an amine structure. Among the diamines having an ether structure, a diamine having a glycol skeleton is preferable. When the polyimide resin has a structural unit derived from a diamine having an ether structure, particularly a structural unit derived from a diamine having a glycol skeleton, heating the heat-peelable sheet reduces the shear adhesive strength. Can do. With respect to this phenomenon, the present inventors, when heated to a high temperature, cause the ether structure or the glycol skeleton to desorb from the resin constituting the heat-peelable sheet, and this debonding reduces the shear adhesive force. I guess that.
Note that the ether structure or the glycol skeleton is detached from the resin constituting the heat-peelable sheet, for example, FT-IR (Fourier Transform Infrared Spectroscopy) before and after heating at 300 ° C. for 30 minutes. The spectra can be confirmed by comparing the spectra of 2800 to 3000 cm ⁻¹ before and after heating. Specifically, the spectral peak intensity of 2800 to 3000 cm ⁻¹ before heating is compared with the spectral peak of 2800 to 3000 cm ⁻¹ after heating, based on the spectral intensity of the benzene ring (spectral intensity of 1500 cm ⁻¹ ). The amount of decrease is obtained by the following equation (3). And when the reduction | decrease amount is 1.0% or more, it can be judged that the said ether structure or the said glycol frame | skeleton has detach | desorbed from resin which comprises a heat-peelable sheet | seat.
Formula (3):
[(Spectrum peak intensity 2800 to 3000 cm ^-1 after heating) / (spectral intensity of 1500cm ^-1 after heating)] / [(spectrum peak intensity 2800 to 3000 cm ^-1 before heating) / (before heating 1500cm ⁻¹ spectral intensity)] × 100 (%)

  Examples of the diamine having a glycol skeleton include a polypropylene glycol structure and a diamine having one amino group at each end, a polyethylene glycol structure, and one amino group at each end. Examples thereof include a diamine having a polytetramethylene glycol structure and a diamine having an alkylene glycol such as a diamine having one amino group at each end. Moreover, the diamine which has two or more of these glycol structures and has one amino group in both the ends can be mentioned.

  The molecular weight of the diamine having an ether structure is preferably in the range of 100 to 5000, and more preferably 150 to 4800. When the molecular weight of the diamine having an ether structure is in the range of 100 to 5,000, it is easy to obtain a heat-peelable sheet having high adhesive strength at low temperatures and exhibiting peelability at high temperatures.

  In forming the polyimide resin, in addition to a diamine having an ether structure, another diamine having no ether structure may be used in combination. Examples of other diamines having no ether structure include aliphatic diamines and aromatic diamines. By using in combination with other diamine having no ether structure, the adhesion with the adherend can be controlled. As a mixing ratio of a diamine having an ether structure and another diamine not having an ether structure (parts by weight of diamine having an ether structure: parts by weight of other diamine having no ether structure), 15:85 80:20 is preferable, More preferably, it is 20: 80-70: 30. Here, the blending weight part of the diamine having an ether structure is the blending weight part of the diamine having an ether structure when the total blending weight excluding the solvent is 100 parts by weight. Moreover, the compounding weight part of the other diamine which does not have an ether structure is a compounding weight part of the other diamine which does not have an ether structure when the total compounding weight except a solvent is 100 parts by weight.

  Examples of the aliphatic diamine include ethylenediamine, hexamethylenediamine, 1,8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane, 4,9-dioxa-1,12-diaminododecane, , 3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane (α, ω-bisaminopropyltetramethyldisiloxane) and the like. The molecular weight of the aliphatic diamine is usually 50 to 1,000,000, preferably 100 to 30,000.

  Examples of the aromatic diamine include 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, m-phenylenediamine, p-phenylenediamine, and 4,4′-diaminodiphenylpropane. 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) -2,2- Dimethylpropane, 4,4'-diaminobenzophenone, etc. It is. The molecular weight of the aromatic diamine is usually 50 to 1000, preferably 100 to 500. In addition, in this specification, molecular weight means the value (weight average molecular weight) measured by GPC (gel permeation chromatography) and computed by polystyrene conversion.

  Examples of the acid anhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 4,4′-oxydiphthalic dianhydride, 2,2-bis (2, 3-dicarboxyphenyl) hexafluoropropane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), bis (2,3-dicarboxyphenyl) methane dianhydride Bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfone Anhydride, pyromellitic dianhydride, ethylene glycol bis trimellitic dianhydride and the like. These may be used alone or in combination of two or more.

  Examples of the solvent for reacting the acid anhydride with the diamine include N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N, N-dimethylformamide, and cyclopentanone. These may be used alone or in combination. Further, in order to adjust the solubility of raw materials and resins, a nonpolar solvent such as toluene or xylene may be appropriately mixed and used.

The heat-peelable sheet of the present invention preferably has a shear adhesive strength to the silicon wafer at the temperature after holding for 1 minute at any temperature in the temperature range of 200 ° C. or lower of 0.25 kg / 5 × 5 mm or more. More preferably, it is 0.30 kg / 5 × 5 mm or more, and further preferably 0.50 kg / 5 × 5 mm or more. In addition, the heat-peelable sheet has a shear adhesive force to the silicon wafer at the temperature of less than 0.25 kg / 5 × 5 mm after being held for 3 minutes at any temperature in the temperature range greater than 200 ° C. and less than or equal to 500 ° C. Preferably, it is less than 0.10 kg / 5 × 5 mm, and more preferably less than 0.05 kg / 5 × 5 mm.
The “any temperature in a temperature range of 200 ° C. or lower” is not particularly limited as long as it is 200 ° C. or lower. For example, any temperature in a temperature range of −20 to 195 ° C., a temperature of 0 to 180 ° C. Any temperature in the region can be any temperature in the temperature region of 20 to 150 ° C.
In addition, the shear adhesion of the heat-peelable sheet to the silicon wafer is less than 0.25 kg / 5 × 5 mm (more preferably less than 0.10 kg / 5 × 5 mm, and even more preferably less than 0.05 kg / 5 × 5 mm). The temperature is not particularly limited as long as it is any temperature in the temperature range greater than 200 ° C. and less than or equal to 500 ° C., preferably greater than 205 ° C. and less than or equal to 400 ° C., more preferably 210 ° C. Over 300 ° C.
After holding for 1 minute at any temperature in the temperature range of 200 ° C. or lower, the shear adhesive force to the silicon wafer at the temperature is 0.25 kg / 5 × 5 mm or higher, and in the temperature range of 200 ° C. or higher and 500 ° C. or lower. When the shear adhesive strength to the silicon wafer at the temperature after holding at any temperature for 3 minutes is less than 0.25 kg / 5 × 5 mm, the temperature is set to any temperature in the temperature range of 200 ° C. or more and 500 ° C. or less. When held for 1 minute, the shear adhesive strength is reduced as compared with the case after holding for 1 minute at any temperature in the temperature range of 200 ° C. or lower. The shear adhesive strength of the heat-peelable sheet can be controlled by, for example, the number of functional groups contained in the heat-peelable sheet.

In addition, even if the said heat-peelable sheet | seat is 200 degrees C or less, if it hold | maintains for a long time (for example, 30 minutes or more), the said shearing adhesive force with respect to a silicon wafer may become less than 0.25kg / 5x5mm. is there. Further, even if the peelable sheet is kept at a temperature higher than 200 ° C. (for example, 210 to 400 ° C.), if it is a short time (for example, within 0.1 minutes), the shear adhesive force to the silicon wafer is It may not be less than 0.25 kg / 5 × 5 mm.
That is, “the shear adhesive force to the silicon wafer at the temperature after holding for 3 minutes at any temperature in the temperature range greater than 200 ° C. and less than 500 ° C. is less than 0.25 kg / 5 × 5 mm” It is an index for evaluating the property, and when “any temperature in a temperature range of greater than 200 ° C. and less than or equal to 500 ° C.” is set, it means that the shear adhesive force to the silicon wafer is immediately less than 0.25 kg / 5 × 5 mm. Not what you want. Further, unless the temperature is set to “any temperature in the temperature range greater than 200 ° C. and less than or equal to 500 ° C.”, this does not mean that peelability is not exhibited.

  The heat peelable sheet preferably has a dynamic hardness of 10 or less, more preferably 9 or less, and even more preferably 8 or less. Moreover, although the said dynamic hardness is so preferable that it is small, it is 0.001 or more, for example. When the dynamic hardness is 10 or less, the adhesive force of the heat-peelable sheet to the adherend can be made sufficient.

  The heat-peelable sheet preferably has a weight reduction rate of less than 1% by weight after being immersed in a 3% by weight tetramethylammonium hydroxide aqueous solution for 5 minutes, more preferably less than 0.9% by weight. More preferably, it is less than 0.8% by weight. Moreover, although the said weight decreasing rate is so preferable that it is small, it is 0 weight% or more and 0.001 weight% or more, for example. If the weight loss after immersion in a 3% tetramethylammonium hydroxide aqueous solution for 5 minutes is less than 1% by weight, the dissolution into the 3% by weight tetramethylammonium hydroxide aqueous solution is small. In particular, the solvent resistance against tetramethylammonium hydroxide aqueous solution can be improved. The weight reduction rate of the heat-peelable sheet can be controlled by, for example, the composition of the diamine used (solubility of the diamine in tetramethylammonium hydroxide aqueous solution).

  When the heat-peelable sheet is peeled off after being bonded to a silicon wafer, the increase amount of particles of 0.2 μm or more on the silicon wafer surface is 1000/6 inches compared with that before being bonded to the silicon wafer. The number of wafers is preferably less than 900, more preferably less than 900/6 inch wafers, and even more preferably less than 800/6 inch wafers. When the amount of particles of 0.2 μm or more on the surface of the silicon wafer when peeled after being bonded to the silicon wafer is less than 1000/6 inch wafers before being bonded to the silicon wafer, Later adhesive residue can be suppressed.

(Manufacture of heat-peelable sheet)
The heat-peelable sheet according to the present embodiment is produced as follows, for example. First, a solution containing the polyamic acid is prepared. The polyamic acid may optionally contain an additive. Next, the solution is applied on a substrate to a predetermined thickness to form a coating film, and then the coating film is dried under a predetermined condition. Examples of the base material include metal foil such as SUS304, 6-4 alloy, aluminum foil, copper foil, Ni foil, polyethylene terephthalate (PET), polyethylene, polypropylene, fluorine-based release agent, and long-chain alkyl acrylate release agent. A plastic film, paper, or the like whose surface is coated with a release agent such as, can be used. Moreover, it does not specifically limit as a coating method, For example, roll coating, screen coating, gravure coating, etc. are mentioned. As drying conditions, for example, the drying temperature is 50 to 150 ° C. and the drying time is 3 to 30 minutes. Thereby, the heat exfoliation type sheet concerning this embodiment is obtained.

  The heat-peelable sheet can be used after being peeled from the substrate. Moreover, a heat peelable sheet | seat is good also as a heat peelable sheet | seat with a support body transferred to a support body. The heat-peelable sheet may be produced by directly applying a solution containing polyamic acid to a support to form a coating film, and then drying the coating film under predetermined conditions. When used as a heat-peelable sheet with a support, the rigidity is stronger than when the heat-peelable sheet is used alone, which is preferable in terms of reinforcing the adherend.

  The support is not particularly limited, and examples thereof include compound wafers such as silicon wafers, SiC wafers, and GaAs wafers, glass wafers, metal foils such as SUS, 6-4 Alloy, Ni foil, and Al foil. In the case of adopting a round shape in plan view, a silicon wafer or a glass wafer is preferable. Moreover, when it is a rectangle by planar view, a SUS board or a glass plate is preferable.

  The said support body may be used individually and may be used in combination of 2 or more type. The thickness of the support is usually about 100 μm to 20 mm.

  The application of the heat-peelable sheet is not particularly limited, but can be used, for example, in the manufacturing process of a semiconductor device. More specifically, for example, it can be used in a step of encapsulating a semiconductor chip with a resin or a step of forming a conductive through hole (TSV) penetrating a silicon chip. In addition, when sealing with resin, it can be attached to the back side of the lead frame and used for the purpose of preventing resin leakage. It can also be used for processing glass members (for example, lenses), color filters, touch panels, and power modules.

In addition, the heat-peelable sheet may be used for manufacturing a semiconductor device having a structure in which a semiconductor chip is mounted on a printed circuit board (see, for example, JP 2010-141126 A). it can. That is, it can be used as a heat-peelable sheet in the following semiconductor device manufacturing method.
A method of manufacturing a semiconductor device having a structure in which a semiconductor chip is mounted on a printed circuit board,
Preparing a support having a heat-peelable sheet;
Forming a printed circuit board on the thermally peelable sheet of the support;
Mounting a semiconductor chip on the wired circuit board;
After the mounting, a method of manufacturing a semiconductor device comprising: a step of peeling the support together with the heat-peelable sheet with the surface of the heat-peelable sheet opposite to the support as an interface.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, blending amounts, and the like described in this example are not intended to limit the gist of the present invention only to those unless otherwise limited.

Example 1
In an atmosphere under a nitrogen stream, polyether diamine (manufactured by Heinzmann, D-400, molecular weight: 422.6) 10.66 g, 4,4′- in 99.16 g of N, N-dimethylacetamide (DMAc). Diaminodiphenyl ether (DDE, molecular weight: 200.2) 4.13 g and pyromellitic dianhydride (PMDA, molecular weight: 218.1) 10.0 g were mixed and reacted at 70 ° C. to prepare polyamic acid solution A. Obtained. After cooling to room temperature (23 ° C.), the polyamic acid solution A was applied onto the mirror surface of an 8-inch silicon wafer with a spin coater and dried at 90 ° C. for 20 minutes to obtain a support A with polyamic acid. The support A with polyamic acid was heat-treated at 300 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration: 100 ppm or less) to form a polyimide film (thermally peelable sheet) having a thickness of 30 μm. A was obtained. The imidation ratio of the heat-peelable sheet according to Example 1 was 99.9%.

(Example 2)
In an atmosphere under a nitrogen stream, aromatic diamine oligomer (Ihara Chemical Co., Elastomer 1000, molecular weight: 1229.7) 14.86 g, 4,4 ′ in 67.41 g of N, N-dimethylacetamide (DMAc). -Support with polyamic acid by mixing and reacting 6.76 g of diaminodiphenyl ether (DDE, molecular weight: 200.2) and 10.0 g of pyromellitic dianhydride (PMDA, molecular weight: 218.1) at 70 ° C B was obtained. After cooling to room temperature (23 ° C), the polyamic acid solution B is applied onto a SUS foil (thickness 38 µm) so that the thickness after drying is 50 µm, dried at 90 ° C for 20 minutes, and with polyamic acid A support B was obtained. The support B with polyamic acid is heat-treated at 300 ° C. for 2 hours in a nitrogen atmosphere (oxygen concentration: 100 ppm or less) to form a polyimide film (thermally peelable sheet) having a thickness of 50 μm, and the support with thermally peelable sheet B was obtained. The imidation ratio of the heat-peelable sheet according to Example 2 was 90%.

(Example 3)
Polyether diamine (manufactured by Heinzmann, D-4000, molecular weight: 4023.5), 18.98 g, 4,4′-diamino in 148.87 g of N, N-dimethylacetamide (DMAc) in an atmosphere under a nitrogen stream. Diphenyl ether (DDE, molecular weight: 200.2) 8.24 g and pyromellitic dianhydride (PMDA, molecular weight: 218.1) 10.0 g were mixed and reacted at 70 ° C. to obtain polyamic acid solution C. It was. After cooling to room temperature (23 ° C), the polyamic acid solution C was applied on a SUS foil (thickness 38 µm) so that the thickness after drying was 50 µm, dried at 90 ° C for 20 minutes, and with polyamic acid A support C was obtained. The support C with polyamic acid is heat-treated at 250 ° C. for 1.5 hours in a nitrogen atmosphere (oxygen concentration: 100 ppm or less) to form a polyimide film (thermally peelable sheet) having a thickness of 50 μm, with a thermally peelable sheet A support C was obtained. The imidation ratio of the heat-peelable sheet according to Example 3 was 80.5%.

(Comparative Example 1)
In an atmosphere under a nitrogen stream, 9.18 g of 4,4′-diaminodiphenyl ether (DDE, molecular weight: 200.2) and 36.42 g of N, N-dimethylacetamide (DMAc) and pyromellitic dianhydride A product (PMDA, molecular weight: 218.1) 10.0 g was mixed and reacted at 70 ° C. to obtain a polyamic acid solution I. After cooling to room temperature (23 ° C.), the polyamic acid solution I was applied onto the mirror surface of an 8-inch silicon wafer with a spin coater and dried at 90 ° C. for 20 minutes to obtain a support I with polyamic acid. The support I with polyamic acid was heat-treated at 300 ° C. for 2 hours under a nitrogen atmosphere (oxygen concentration: 100 ppm or less) to form a polyimide film (thermally peelable sheet) having a thickness of 30 μm. I was obtained. The imidation ratio of the heat-peelable sheet according to Comparative Example 1 was 75%.

The imidization ratios of Examples and Comparative Examples were obtained by measuring the peak intensity of imide groups using 1H-NMR (proton nuclear magnetic resonance, manufactured by JEOL Ltd., LA400). Specifically, a solution for producing a heat-peelable sheet (solution containing polyamic acid) is applied and dried (drying condition: 90 ° C. for 20 minutes), and imide is obtained under the imidization conditions described in Examples and Comparative Examples. Make it. In this state, the peak area A derived from the OR proton (the peak area derived from the OR proton when the polyamic acid diamine and acid anhydride are not closed) and the imide group NR proton derived The peak area B (peak area derived from N—R protons when the diamine and acid anhydride of the polyamic acid are in a closed state) was determined, and the imidization ratio (%) was determined from the formula (2).
Formula (2):
[(B) / (A + B)] × 100 (%)

(Measurement of thermal curing rate)
Using a differential scanning calorimeter manufactured by SII, product name “DSC6220”, the thermosetting rate was measured as follows.
The temperature was increased from room temperature (23 ° C.) using a state in which a solution for producing a heat-peelable sheet according to Examples and Comparative Examples (solution containing polyamic acid) was applied and dried (condition: 90 ° C. for 20 minutes). The calorific value (total calorific value) when the temperature was raised to 500 ° C. (the temperature at which the thermosetting reaction was assumed to be completely completed) was measured at a temperature rate of 10 ° C./min. In addition, using a sheet that has been manufactured as a heat-peelable sheet according to Examples and Comparative Examples, 500 ° C. (thermosetting reaction is completely completed from room temperature (23 ° C.) under a temperature increase rate of 10 ° C./min The amount of heat generated when the temperature was raised to (the temperature assumed to have been obtained) (the amount of heat generated after manufacturing the heat-peelable sheet) was measured. Then, the thermosetting rate was obtained by the following formula (1).
Formula (1):
[1-((Amount of heat generated after manufacturing the heat-peelable sheet) / (Total amount of heat generated))] × 100 (%)
As the exotherm, the reaction exotherm in the temperature range of ± 5 ° C. of the reaction exothermic peak temperature measured with a differential scanning calorimeter is used.
The results are shown in Table 1.

(Measurement of shear adhesion to silicon wafer)
A 5 mm square (500 μm thick) silicon wafer chip is placed on a heat-peelable sheet formed on a support (silicon wafer, SUS foil, or glass wafer) and laminated under conditions of 60 ° C. and 10 mm / s. Then, using a shear tester (Dage, Dage 4000), the shear adhesive strength between the heat-peelable sheet and the silicon wafer chip was measured. The conditions for the shear test were as follows. The results are shown in Table 1.
<Condition 1 of shear test>
Stage temperature: 200 ° C
Time from holding on stage to starting shearing adhesive strength measurement: 1 minute Measurement speed: 500 μm / s
Measurement gap: 100 μm
<Condition 2 of shear test>
Stage temperature: 260 ° C
Time from holding on stage to starting shearing adhesive strength measurement: 3 minutes Measurement speed: 500 μm / s
Measurement gap: 100 μm

(Measurement of weight loss when immersed in tetramethylammonium hydroxide aqueous solution)
First, the support body was peeled from the support body with a heat peelable sheet which concerns on an Example and a comparative example. Next, the peeled heat-peelable sheet was cut into a 100 mm square and its weight was measured. Next, it was immersed for 5 minutes in 3 weight% tetramethylammonium hydroxide aqueous solution (TMAH) of 23 degreeC. After sufficiently washing with water, drying was performed at 150 ° C. for 30 minutes. Then, the weight was measured and set as the weight after immersion.
The weight reduction rate was determined by the following formula. The results are shown in Table 1.
(Weight reduction rate (% by weight)) = [1-((weight after immersion) / (weight before immersion))] × 100

(Adhesive residue evaluation)
First, the support body was peeled from the support body with a heat peelable sheet which concerns on an Example and a comparative example. Next, the heat-peelable sheets of Examples and Comparative Examples were processed into a size of 6 inches in diameter, and laminated on a wafer of 8 inches in diameter at 60 ° C. and 10 mm / s. Then, it was left for 1 minute and peeled off. Using a particle counter (SFS6200, manufactured by KLA), the number of particles of 0.2 μm or more on the surface of an 8-inch diameter wafer was measured. Further, in comparison with the case before lamination, the case where the amount of increase in particles after peeling was less than 1000/6 inch wafer was evaluated as ◯, and the case where it was 1000 particles / 6 inch or more was evaluated as x. The results are shown in Table 1.

(Peeling temperature)
About the heat-peelable sheet | seat which concerns on an Example and a comparative example, it was set as the size of 30 mm square, and 10 mm square (thickness: 2 mm) glass was affixed on the heat-peelable sheet | seat using the laminator. Using this sample, the glass was heated with a high temperature observation device (product name: SK-5000) manufactured by Sanyo Seiko under the conditions of a heating rate of 4 ° C./min and a measurement temperature of 20 to 350 ° C. Was confirmed to peel off from the heat-peelable sheet. The results are shown in Table 1.

(Gas visual temperature)
About the heat-peelable sheet | seat which concerns on an Example and a comparative example, it was set as the size of 30 mm square, and 10 mm square (thickness: 2 mm) glass was affixed on the heat-peelable sheet | seat using the laminator. Using this sample, it was heated with a high-temperature observation device (product name: SK-5000) manufactured by Sanyo Seiko under the conditions of a heating rate of 4 ° C./minute and a measurement temperature of 20 to 350 ° C. The temperature at which smoke was generated was confirmed. The results are shown in Table 1.

(Dynamic hardness)
About the heat-peelable sheet according to the example, using a hardness meter (product name: DUH-210) manufactured by Shimadzu Corporation and an indenter (trade name: Triangular115, manufactured by Shimadzu Corporation), the load is removed at a load of 0.5 mN. A load test was performed and dynamic hardness was measured. The results are shown in Table 1.

Claims (2)

  A heat-peelable sheet having a thermosetting rate of 80% or more. Including polyimide resin,
A heat-peelable sheet having an imidization ratio of 80% or more.