JP7503915B2 - Cleaning Sheet - Google Patents

Description

The present invention relates to a cleaning sheet.

A variety of cleaning materials have been developed to clean deposits on the surfaces of precision equipment, etc., depending on the use and shape of the equipment. In particular, special cleaning materials have been proposed for cleaning probes (needles) used to test the continuity of chips formed on semiconductor wafers.

For the above-mentioned uses, for example, Patent Document 1 discloses a cleaning pad having a coating layer formed on at least one surface of a foam sheet and having a Mohs hardness set in the range of 7 to 9, and it is said that this cleaning pad can remove deposits attached to a probe pin without excessively wearing down the probe pin. Also, for example, Patent Document 2 discloses a cleaning sheet having a cleaning layer, which contains a polymer component having a glass transition point Tg, and which has a predetermined tensile storage modulus in a temperature range equal to or higher than the Tg and a predetermined tensile storage modulus in a temperature range below the Tg, and it is said that this cleaning sheet can remove deposits from a probe without wearing down the probe.

JP 2005-091213 A Patent No. 5675472

In the field of semiconductor elements for power control (power devices), a higher level of heat resistance is required than in the field of ordinary semiconductors, so continuity tests are also carried out under high-temperature conditions, and the probes used in these tests also become hot during the test process. When such probes are used repeatedly, the probe surface needs to be cleaned each time, and for the sake of the test process, it is desirable to subject the probe to in-situ cleaning. In other words, there is a demand for cleaning materials that enable probe cleaning under high-temperature conditions.

Here, in the cleaning pad described in Patent Document 1, it is preferable to use a urethane resin as the coating layer. However, when a urethane resin is used as the coating layer, volatile matter derived from the resin components, known as outgassing, is generated under high temperature conditions, for example, above 200°C. Such outgassing leads to contamination of semiconductor elements, semiconductor devices, and the like. In the manufacturing process of semiconductor devices, where even a small amount of contamination is problematic, preventing outgassing is an important issue from the viewpoint of avoiding a decrease in yield and a decrease in quality.

Next, in the cleaning pad described in Patent Document 2, it is said that a heat-resistant resin can be used as the cleaning layer, but on the other hand, the adhesive layer that can be included in addition to the cleaning layer is said to be made of a normal adhesive such as an acrylic adhesive or a rubber adhesive. The cleaning pad is generally used by fixing (attaching) it to a table, and when a cleaning pad having the above-mentioned adhesive layer is used under high-temperature conditions exceeding 200°C, the adhesive components volatilize, and in this case too, the problem of outgassing occurs. Furthermore, the problem of delamination due to deterioration of the adhesive layer also occurs.

As mentioned above, there is still room for improvement in conventional technology in terms of preventing outgassing, rather than simply cleaning the probe, assuming use under high temperature conditions.

The present invention was made in consideration of the problems with the conventional technology described above, and aims to provide a cleaning sheet that is designed for use under high temperature conditions and can clean a probe while preventing outgassing.

The inventors conducted extensive research to solve the above problems. As a result, they discovered that the above problems could be solved by using specific materials for the coating layer and adhesive layer that make up the cleaning sheet, and thus completed the present invention.

That is, the present invention includes the following aspects.
[1]
A substrate layer having a plurality of bubbles;
a coating layer disposed on one surface of the base layer, having a cleaning surface for cleaning an object to be cleaned, and containing at least one of an imide resin and an epoxy resin;
an adhesive layer disposed on the other surface of the base layer and containing at least one of an imide resin and an epoxy resin;
Including,
The coating layer is subjected to a thermogravimetric differential thermal analysis, and the weight loss rate R1 calculated from the weight when the coating layer is heated from 40° C. to 210° C. at a rate of 15° C./min, maintained at 210° C. for 10 minutes, and cooled to 40° C. as a reference, and the weight when the coating layer is further heated from 40° C. to 210° C. at a rate of 15° C./min, and maintained at 210° C. for 10 minutes, is 0.10 mass% or less.
[2]
The cleaning sheet according to [1], wherein the base layer is subjected to a thermogravimetric differential thermal analysis, and the weight loss rate R2 calculated from the weight when the base layer is heated from 40° C. to 210° C. at a rate of 15° C./min, held at 210° C. for 10 minutes, and cooled to 40° C. is taken as a reference, and the weight when the base layer is further heated from 40° C. to 210° C. at a rate of 15° C./min, and held at 210° C. for 10 minutes is 0.10 mass% or less.
[3]
The cleaning sheet according to [1] or [2], wherein the adhesive layer is subjected to a thermogravimetric differential thermal analysis, and the weight loss rate R3 calculated from the weight when the adhesive layer is heated from 40° C. to 210° C. at a rate of 15° C./min, held at 210° C. for 10 minutes, and cooled to 40° C. is taken as a standard, and the weight when the adhesive layer is further heated from 40° C. to 210° C. at a rate of 15° C./min, held at 210° C. for 10 minutes, is 0.10% by mass or less.
[4]
The cleaning sheet according to any one of [1] to [3], wherein an average pore size of the plurality of bubbles in the base layer is 10 μm or more and 100 μm or less.
[5]
The cleaning sheet according to any one of [1] to [4], wherein the coating layer contains abrasive grains.
[6]
The cleaning sheet according to [5], wherein the abrasive grains have a grain size of 0.5 μm or more and 10 μm or less.
[7]
The cleaning sheet according to any one of [1] to [6], wherein the base layer contains a fluororesin.
[8]
The cleaning sheet according to any one of [1] to [7], which is for cleaning a probe.
[9]
The cleaning sheet according to claim 8, further comprising a base layer for introduction into a cleaning device of the probe.

The present invention provides a cleaning sheet that can clean a probe while preventing outgassing, even when used under high temperature conditions.

1 is a schematic diagram illustrating one aspect of a cleaning sheet according to an embodiment of the present invention;

The following describes in detail the embodiment of the present invention (hereinafter, simply referred to as the "present embodiment"). Note that the present embodiment is an example for explaining the present invention, and the present invention is not limited to the following embodiment.

[Cleaning sheet]
The cleaning sheet of this embodiment includes a base layer having a plurality of bubbles, a coating layer arranged on one side of the base layer, having a cleaning surface for cleaning an object to be cleaned, and containing at least one of an imide resin and an epoxy resin, and an adhesive layer arranged on the other side of the base layer and containing at least one of an imide resin and an epoxy resin, and the coating layer is subjected to a thermogravimetric differential thermal analysis, heated from 40° C. to 210° C. at a rate of 15° C./min, held at 210° C. for 10 minutes, and cooled to 40° C. as a reference, and a weight reduction rate R1 calculated from the mass when the coating layer is heated from 40° C. to 210° C. at a rate of 15° C./min and held at 210° C. for 10 minutes is 0.10% by mass or less. The weight reduction rate R1 is a value based on the mass of the coating layer when subjected to the thermogravimetric differential thermal analysis (before heating from 40° C.). Because of this configuration, the cleaning sheet of this embodiment can clean the probe while preventing the generation of outgassing, even when used under high temperature conditions.

An example of the cleaning sheet of this embodiment will be described with reference to FIG. 1. The cleaning sheet 10 comprises a base layer 1, a coating layer 2 having a cleaning surface 2a for cleaning the object W, and an adhesive layer 3 formed on the opposite side of the base layer 1 to the surface on which the coating layer 2 is located. The cleaning sheet 10 is fixed to a holding platen by the adhesive layer 3, and its relative position with respect to the object W is also fixed. Next, the cleaning surface 2a of the coating layer 2 is brought into contact with the object W, and the cleaning sheet 10 is slid over the surface of the object W to perform cleaning. The object W to be cleaned is not particularly limited, but a probe can be preferably used, and in particular, a probe for testing the continuity of chips on a semiconductor wafer, which requires cleaning at high temperatures, can be preferably used.

(Coating Layer)
The coating layer in this embodiment contains at least one of an imide resin and an epoxy resin, and the weight reduction rate R1 calculated from the mass when the coating layer is heated from 40°C to 210°C at 15°C/min, held at 210°C for 10 minutes, and cooled to 40°C, at a rate of 0.10% by mass or less. Here, the weight reduction amount in the thermogravimetric differential thermal analysis corresponds to the amount of volatile matter (i.e., outgassing) derived from the resin and other additives contained in the coating layer when the coating layer is placed under the same temperature conditions. In other words, the weight reduction rate R1 being 0.10% by mass or less means that the amount of outgassing derived from the coating layer is reduced to 0.10% by mass or less under the above temperature conditions.
As described above, in the cleaning sheet of the present embodiment, the amount of outgassing is sufficiently reduced even under the above-mentioned temperature conditions in the coating layer having a cleaning surface for cleaning an object to be cleaned, so that even when used under high temperature conditions, it is possible to clean a probe while preventing the generation of outgassing.

The coating layer in the present embodiment is not particularly limited as long as it contains at least one of an imide resin and an epoxy resin and the weight reduction rate R1 is 0.10 mass % or less.
The imide resin that can be contained in the coating layer is not particularly limited, but examples thereof include aromatic polyimide resins. These can be used alone or in combination of two or more. Commercially available products can also be used for the above, and examples thereof include, but are not limited to, products manufactured by IMITEX Corporation under the trade names "IMIX-300" and "IMIX-100."
The above-mentioned imide resins can be used alone or in combination of two or more.
The epoxy resin that can be contained in the coating layer is not particularly limited, but examples thereof include aromatic epoxy resins, and among them, phenolic epoxy resins are preferred. Examples of epoxy resin prepolymers include bisphenol A type epoxy resins, bisphenol F type epoxy resins, and novolac type epoxy resins, and examples of curing agents include polyamines, polyamides, novolac type phenolic resins, and acid anhydrides. Among these, from the viewpoint of heat resistance and reducing outgassing, epoxy resins that use novolac type phenolic resins as curing agents are preferred. These can be used alone or in combination of two or more. Commercially available products can also be used for the above, and are not limited to the following examples, but examples of prepolymers include epoxy resin prepolymers manufactured by Mitsubishi Chemical Corporation (trade name "YX7105"), and examples of curing agents include novolac type phenolic resins manufactured by Gun-ei Chemical Co., Ltd. (trade name "PSM4261").
The above-mentioned epoxy resins can be used alone or in combination of two or more.

Methods for making the weight loss rate R1 of the coating layer in this embodiment 0.10% by mass or less include, but are not limited to, using a relatively high molecular weight imide resin and/or epoxy resin, using an imide resin and/or epoxy resin having a chemical structure such as an aromatic ring structure, using an epoxy resin using a novolac type phenolic resin as a curing agent, or, as a pretreatment, heating the cleaning sheet as a whole at a temperature exceeding 200°C for about 2 to 4 hours to remove volatile components, or setting the content of compounds that are difficult to decompose or volatilize under high temperature conditions, such as the above-mentioned preferred imide resin and/or epoxy resin, to 80% by mass or more based on the resin components of the coating layer. On the other hand, even if the above-mentioned pretreatment is performed, if the coating layer is formed from a material other than the imide resin and/or epoxy resin, problems such as poor heat resistance and changes in physical properties after short-term use may occur even if the generation of outgassing can be suppressed.

In the present embodiment, the coating layer preferably contains abrasive grains in order to perform more effective cleaning. In this specification, the abrasive grains refer to particulate components capable of removing foreign matter adhering to the object to be cleaned, and generally have a particle size of about 0.1 μm to about 1000 μm. The particle size of the abrasive grains can be measured, for example, by a laser diffraction method using a laser diffraction type particle size distribution measuring device (e.g., MT3300 manufactured by Microtrack Bell).
Examples of the abrasive grains include, but are not limited to, diamond, white alumina, silicon carbide, boron carbide, cerium oxide, zirconium oxide, chromium oxide, iron oxide, titanium oxide, silicon dioxide, manganese dioxide, manganese trioxide, zirconium silicate, barium carbonate, glass, boron nitride, titanium nitride, etc. These can be used alone or in combination of two or more. Commercially available products can also be used for the above, and examples include, but are not limited to, Fujimi Incorporated's product name "WA4000" (finely ground fused alumina), etc.
The particle size of the abrasive grains in this embodiment is not particularly limited, but from the viewpoint of cleaning performance and prevention of damage to the object to be cleaned, it is preferably 70% or less of the coating thickness of the coating layer, more preferably 60% or less. More specifically, it is preferably 0.5 μm or more and 20 μm or less, more preferably 1.0 μm or more and 10 μm or less.
In this embodiment, the content of the abrasive grains is preferably 30 to 90 mass % of the entire coating layer, and more preferably 40 to 80 mass %. Within this range, there is a tendency for both cleaning performance and prevention of damage to the object to be cleaned to be achieved.

In addition to the resin component and the abrasive grain component, the coating layer may contain known additives in combination within the scope of the present invention. Examples of additives include curing accelerators, catalysts, dyes, pigments, water repellents, hydrophilic agents, and antistatic agents. These can be used alone or in combination of two or more.

(Base layer)
The substrate layer in this embodiment is not particularly limited as long as it can form a coating layer on one side and an adhesive layer on the other side. Examples of materials that can be used for the substrate layer include polyolefins such as low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-butene copolymer, and ethylene-hexene copolymer. Other examples of materials that can be used for the substrate layer include ethylene-vinyl acetate copolymers, ionomer resins, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester (random, alternating) copolymers, polyurethane, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonates, polyimides, polyether ether ketones, polyetherimides, polyamides, wholly aromatic polyamides, polyphenylsulfides, aramids (paper), glass, glass cloths, fluororesins, polyvinyl chloride, polyvinylidene chloride, cellulose-based resins, silicone resins, metals (foils), and paper. These can be used alone or in combination of two or more.
Of the above, the base layer preferably contains a fluororesin, and more preferably contains a fluororesin foam.
The apparent density of the fluororesin foam (measured according to Japanese Industrial Standards (JIS K 6505)) is not particularly limited, but is preferably 0.2 to 1.5 g/cm ³ , and more preferably 0.3 to 0.8 g/cm ³ .
The Shore A hardness (measured based on the Japanese Industrial Standard (JIS-K-7311)) of the fluororesin foam is not particularly limited, but is preferably 5 to 50 degrees, and more preferably 10 to 30 degrees. The 100% modulus (100% modulus is the value obtained by dividing the tension applied when a sheet made of the resin is stretched 100%, i.e., when stretched to twice its original length, by unit area) of the fluororesin foam is not particularly limited, but is preferably 0.1 to 3.0 MPa, and more preferably 0.3 to 1.5 MPa.
As the fluororesin foam, commercially available products can be used, and examples thereof include, but are not limited to, the product name "HS-DF700-37HS" manufactured by Sanpuku Kogyo Co., Ltd.

In this embodiment, the weight reduction rate R2 calculated from the mass of the substrate layer when it is heated from 40°C to 210°C at 15°C/min, held at 210°C for 10 minutes, and cooled to 40°C, at 15°C/min from 40°C to 210°C and held at 210°C for 10 minutes is preferably 0.10% by mass or less. The weight reduction rate R2 is a value based on the mass of the substrate layer when it is subjected to the thermogravimetric differential thermal analysis (before heating from 40°C). Here, the weight reduction amount corresponds to the amount of volatile matter (i.e., outgassing) derived from the resin and other additives contained in the substrate layer when the substrate layer is placed under the same temperature conditions. In other words, when the weight reduction rate R2 is 0.10% by mass or less, the amount of outgassing derived from the substrate layer tends to be sufficiently reduced under the above temperature conditions.

In this embodiment, methods for making the weight loss rate R2 of the base layer 0.10% by mass or less include, but are not limited to, using a highly heat-resistant fluororesin, and pre-treating the cleaning sheet by heating the entire sheet at a temperature exceeding 200°C for about 2 to 4 hours to remove volatile components.

The average pore size of the plurality of bubbles in the base layer is not particularly limited, but if it is too small, the cushioning property decreases, and if it is too large, the unevenness due to the openings on the surface of the coating layer may adversely affect the cleaning performance, so it is preferably 10 μm to 100 μm, more preferably 30 μm to 70 μm. The average pore size can be calculated, for example, by enlarging and observing the cross section of the base material or the surface on which the openings can be confirmed with a microscope (VH-6300, manufactured by KEYENCE), binarizing the obtained image with image processing software (ImageAnalyzer V20 LAB Ver. 1.3, manufactured by Nikon), measuring the circle equivalent diameter from the area of each bubble, and calculating the average value. In this case, the cutoff value (lower limit) is set to 10 μm, and it is excluded as a noise component. The average pore size can be adjusted to the above range, for example, by adding a foaming agent or a foam stabilizer during the production of the base layer.

In addition to the resin components (prepolymer and curing agent), the base layer may contain known additives in combination within the scope of the present invention. Examples of additives include foaming agents, foam stabilizers, abrasive grains, curing accelerators, catalysts, dyes, pigments, water repellents, hydrophilic agents, and antistatic agents. These can be used alone or in combination of two or more.

(Adhesive Layer)
The adhesive layer in this embodiment is not particularly limited as long as it contains at least one of an imide resin and an epoxy resin.
The imide resin that can be contained in the adhesive layer is not particularly limited, but for example, the resins listed for the coating layer can be used. Commercially available products can also be used, and examples include, but are not limited to, "IMIX-300" and "IMIX-100" manufactured by IMITEX Corporation.
The above-mentioned imide resins can be used alone or in combination of two or more.
The epoxy resin that can be contained in the adhesive layer is not particularly limited, but for example, the resins listed for the coating layer can be used. Commercially available products can also be used for the above, and although not limited to the following examples, examples of the prepolymer include Mitsubishi Chemical's epoxy resin prepolymer (product name "YX7105"), and examples of the curing agent include Gun-ei Chemical's novolac-type phenolic resin (product name "PSM4261").
The above-mentioned epoxy resins can be used alone or in combination of two or more.

In this embodiment, the weight reduction rate R3 calculated from the mass of the adhesive layer when it is heated from 40°C to 210°C at 15°C/min, held at 210°C for 10 minutes, and cooled to 40°C, at 15°C/min from 40°C to 210°C and held at 210°C for 10 minutes is preferably 0.10% by mass or less. That is, the resins listed in the coating layer can be used. In this case, the resin used in the coating layer and the resin used in the adhesive layer may be the same or different. The weight reduction rate R3 is a value based on the mass of the adhesive layer when it is subjected to the thermogravimetric differential thermal analysis (before heating from 40°C). Here, the weight reduction amount corresponds to the amount of volatile matter (i.e., outgassing) derived from the resin and other additives contained in the adhesive layer when the adhesive layer is placed under the same temperature conditions. That is, when the weight reduction rate R3 is 0.10% by mass or less, the amount of outgassing from the adhesive layer tends to be sufficiently reduced under the above temperature conditions.

Methods for making the weight loss rate R3 of the adhesive layer in this embodiment 0.10% by mass or less include, but are not limited to, using a relatively high molecular weight imide resin and/or epoxy resin, using an imide resin and/or epoxy resin having a chemical structure such as an aromatic ring structure, using an epoxy resin that employs a novolac-type phenolic resin as a curing agent, or, as a pretreatment, heating the cleaning sheet as a whole at a temperature exceeding 200°C for about 2 to 4 hours to remove volatile components, or setting the content of compounds that are difficult to decompose or volatilize under high temperature conditions, such as the above-mentioned preferred imide resins and/or epoxy resins, to 80% by mass or more based on the resin components of the coating layer.

In addition to the resin components (prepolymer and curing agent), the adhesive layer may contain known additives in combination as long as the purpose of the present invention is not impaired. Examples of additives include curing accelerators, catalysts, dyes, pigments, water repellents, hydrophilic agents, and antistatic agents. These can be used alone or in combination of two or more.

(For probe applications)
From the above viewpoint, the cleaning sheet of the present embodiment is preferably applicable to the cleaning of probes, and particularly preferably applicable to the cleaning of probes for continuity testing of semiconductor elements (power devices) for power control, which require cleaning at high temperatures. When applied to such applications, the cleaning sheet of the present embodiment preferably further includes a base layer for introduction into a probe cleaning device. The base layer is preferably bonded by an adhesive layer, and the base layer can be used as a driving means for sliding the cleaning sheet of the present embodiment, but is not limited thereto.

(Optional parts)
The cleaning sheet of the present embodiment may contain optional members other than the above-mentioned base layer, coating layer, and adhesive layer. The optional members are not particularly limited, but examples thereof include a release base material that covers the adhesive surface of the adhesive layer, a protective film that protects the surface, and a stage plate member for a continuity inspection device.

[Method of manufacturing cleaning sheet]
The method for producing the cleaning sheet of the present embodiment is not particularly limited as long as the method can provide the above-described configuration of the cleaning sheet of the present embodiment. Preferred examples of the method for producing the cleaning sheet of the present embodiment are described below.

The cleaning sheet of the present embodiment can be produced, for example but not limited to, by laminating a coating layer on one side of a base layer and laminating an adhesive layer on the other side.
The coating layer can be laminated by a known method, and examples of the method include, but are not limited to, a method using a coating device such as a knife coater, a blade coater, a bar coater, a roll coater, a gravure coater, a screen coater, a curtain coater, or a spray coater.
The adhesive layer can be laminated by a known method, and examples of the method include, but are not limited to, a method using a coating device such as a knife coater, blade coater, bar coater, roll coater, gravure coater, screen coater, curtain coater, spray coater, etc., and a method in which an adhesive sheet formed into a sheet of a desired thickness is laminated on a base layer by pressurizing or heating.
For example, when using the coating device described above, a slurry-like paint is applied to one side of the base layer by the coating device, and the applied paint is dried or the resin component contained in the paint is hardened to form a coating layer and an adhesive layer on the base layer, respectively, thereby producing the cleaning sheet of this embodiment.

The present embodiment will be described in more detail below based on examples and comparative examples, but the present embodiment is not limited to these.

Example 1
A mixture of 89.9% by mass of a flexible epoxy resin having an aromatic group (trade name "YX7105"; manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 485), 9.2% by mass of a curing agent (trade name "PSM4261"; manufactured by Gun-ei Chemical Co., Ltd., novolac-type phenolic resin, hydroxyl equivalent 103), and 0.9% by mass of a reaction accelerator (trade name "TPP-MK"; manufactured by Hokko Chemical Industry Co., Ltd., tetraphenylphosphonium tetra-p-tolylborate) was mixed with white alumina (trade name "WA4000"; average particle size 5 μm; manufactured by Fujimi Incorporated Co., Ltd.) as an abrasive grain to prepare slurry S1. The content of the abrasive grains in the slurry S1 was 70% by mass.
Next, a fluororesin foam (product name "HS-DF700-37HS"; average pore size 50 μm; manufactured by Sanfuku Kogyo Co., Ltd.) was prepared as a substrate layer (Shore A hardness 22, density 0.39 g/cm ³ , 100% modulus 1.28 MPa, thickness 0.5 mm), and slurry S1 was applied to one side of the substrate and cured at 150°C for 30 minutes to form a coating layer with a thickness of 10 μm.
Next, an imide resin (product name "IMIX-300"; manufactured by IMITEX Corporation) was applied to the surface of the base material layer on which the coating layer was formed, opposite the coating layer, and semi-cured at 175°C for 30 minutes to form an adhesive layer having a thickness of 10 µm, thereby obtaining a cleaning sheet.
The resulting cleaning sheets were evaluated as follows.

(Thermogravimetric Differential Thermal Analysis)
From the cleaning sheet, the coating layer (including abrasive grains), the base layer and the adhesive layer were each collected as a 50 mg sample, and pre-treated at 150°C for 2 hours to remove moisture and the like. Then, the samples were subjected to a thermogravimetric differential thermal analysis using a thermal analysis device "TG/DTA EXTER2000" manufactured by SII Nanotechnology Co., Ltd. That is, the weight loss rate calculated from the mass when each sample was heated from 40°C to 210°C at 15°C/min, held at 210°C for 10 minutes, and cooled to 40°C was used as a reference, and the weight loss rate was measured when the sample was heated from 40°C to 210°C at 15°C/min and held at 210°C for 10 minutes. In addition, the weight loss rate is a value calculated from the weight ratio after the second heating and holding, based on the mass of the coating layer, base layer and adhesive layer when the sample was subjected to the thermogravimetric differential thermal analysis for the second time (before heating from 40°C) in order to eliminate the influence of residual moisture and the like.
The weight loss rate of the white alumina used in forming the coating layer was also measured in the same manner as above.

(Check for peeling)
Next, the cleaning sheet was fixed to a silicon wafer via the adhesive layer, and after heating at 250° C. for 1 hour, the presence or absence of peeling of the adhesive layer was visually confirmed.

The composition and evaluation results of the cleaning sheet of Example 1 are shown in Table 1.

Example 2
The above-mentioned white alumina was added as abrasive grains to an imide resin (product name "IMIX-300" manufactured by IMITEX Corporation) to prepare slurry S2. The content of the abrasive grains in slurry S2 was 70 mass %.
A cleaning sheet was produced and evaluated under the same conditions as in Example 1, except that the slurry used to form the coating layer was changed from slurry S1 to slurry S2 and cured at 175° C. for 30 minutes. The results are also shown in Table 1.

Example 3
The above-mentioned white alumina was added as abrasive grains to an imide resin (product name "IMIX-100" manufactured by IMITEX Corporation) to prepare slurry S3. The content of the abrasive grains in slurry S3 was 70 mass %.
A cleaning sheet was produced and evaluated under the same conditions as in Example 1, except that the slurry used to form the coating layer was changed from slurry S1 to slurry S3 and cured at 175° C. for 30 minutes. The results are also shown in Table 1.

(Comparative Example 1)
The above-mentioned white alumina was added as abrasive grains to a vinyl compound (trade name "SP-700"; manufactured by Jujo Chemical Co., Ltd.) to prepare slurry S4. The content of the abrasive grains in slurry S4 was 70 mass %.
A cleaning sheet was produced and evaluated under the same conditions as in Example 1, except that the slurry used to form the coating layer was changed from slurry S1 to slurry S4 and cured at 120° C. for 30 minutes. The results are also shown in Table 1.

(Comparative Example 2)
The above-mentioned white alumina was added as abrasive grains to an unsaturated polyester compound (product name "SIM3200"; manufactured by Jujo Chemical Co., Ltd.) to prepare slurry S5. The content of the abrasive grains in slurry S5 was 70 mass %.
Except for changing the slurry used to form the coating layer from slurry S1 to slurry S5, a cleaning sheet was produced and evaluated under the same conditions as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
The above-mentioned white alumina was added as abrasive grains to a mixture of 83.3 mass% of epoxy resin (trade name "Epilite"; manufactured by Jujo Chemical Co., Ltd.) and 16.7 mass% of the attached amine-based curing agent, Epilite curing agent, to prepare slurry S6. The content of abrasive grains in slurry S6 was 70 mass%.
Except for changing the slurry used to form the coating layer from slurry S1 to slurry S7, a cleaning sheet was produced and evaluated under the same conditions as in Example 1. The results are also shown in Table 1.

All of Examples 1 to 3 were suitable for use as cleaning sheets, particularly for cleaning probes. Among them, the cleaning sheet of Example 1, which used an epoxy resin for the cleaning surface, was preferable in that it had high flexibility and was expected to have good conformability even at low temperatures compared to Examples 2 and 3, which used imide resin. Also, Comparative Example 3, which used an epoxy resin using an amine-based hardener as the coating layer, generated more outgassing than Example 1, which used an epoxy resin using a novolac-type phenol-based hardener, and was therefore unsuitable.

1...base material layer, 2...coating layer, 2a...cleaning surface, 3...adhesive layer, 10...cleaning sheet, W...item to be cleaned.

Claims (9)

A substrate layer having a plurality of bubbles;
a coating layer disposed on one surface of the base layer, having a cleaning surface for cleaning an object to be cleaned, and containing at least one of an imide resin and an epoxy resin;
an adhesive layer disposed on the other surface of the base layer and containing at least one of an imide resin and an epoxy resin;
Including,
The coating layer is subjected to a thermogravimetric differential thermal analysis, and the weight loss rate R1 calculated from the weight when the coating layer is heated from 40° C. to 210° C. at a rate of 15° C./min, maintained at 210° C. for 10 minutes, and cooled to 40° C. as a reference, and the weight when the coating layer is further heated from 40° C. to 210° C. at a rate of 15° C./min, and maintained at 210° C. for 10 minutes, is 0.10 mass% or less. The cleaning sheet according to claim 1, wherein the base layer is subjected to a thermogravimetric differential thermal analysis, and the weight loss rate R2 calculated from the mass when the base layer is heated from 40°C to 210°C at 15°C/min, held at 210°C for 10 minutes, and cooled to 40°C is used as a reference, and the mass when the base layer is further heated from 40°C to 210°C at 15°C/min and held at 210°C for 10 minutes is 0.10% by mass or less. The cleaning sheet according to claim 1 or 2, wherein the adhesive layer is subjected to a thermogravimetric differential thermal analysis, and the weight loss rate R3 calculated from the mass when the adhesive layer is heated from 40°C to 210°C at 15°C/min, held at 210°C for 10 minutes, and cooled to 40°C is used as a reference, and the mass when the adhesive layer is further heated from 40°C to 210°C at 15°C/min and held at 210°C for 10 minutes is 0.10% by mass or less. A cleaning sheet according to any one of claims 1 to 3, wherein the average pore size of the bubbles in the base layer is 10 μm or more and 100 μm or less. The cleaning sheet according to any one of claims 1 to 4, wherein the coating layer contains abrasive grains. The cleaning sheet according to claim 5, wherein the grain size of the abrasive grains is 0.5 μm or more and 10 μm or less. The cleaning sheet according to any one of claims 1 to 6, wherein the base layer contains a fluororesin. The cleaning sheet according to any one of claims 1 to 7, which is for cleaning a probe. The cleaning sheet of claim 8, further comprising a base layer for introduction into a cleaning device of the probe.

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