Method for evaluating heavy metal ion permeability of resin films and adhesive films

Abstract

To provide a novel method for evaluating the heavy metal ion permeability of a resin film.SOLUTION: An evaluation method for heavy metal ion permeability of a resin film includes a first step of obtaining an integral value of heat flow that correlates with the amount of heat of fusion of pore water existing in the pore of a resin film by a method based on thermoporometry, and a second step of evaluating the heavy metal ion permeability of the resin film on the basis of the integral value of the heat flow.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for evaluating the heavy metal ion permeability of a resin film and an adhesive film. [Background technology]

[0002] In recent years, as smartphones, tablet PCs, etc. have become more sophisticated and faster, the semiconductor packages used in them are being required to be even smaller, have higher capacity, are faster, and are thinner, etc. The wafers used in these semiconductor packages are seeing further miniaturization of the wiring, and the chips tend to become even thinner when assembled into semiconductor packages.

[0003] Amid these trends, problems of operational malfunctions caused by trace amounts of heavy metal ions, such as copper ions, have begun to become apparent, particularly in the fields of DRAM and NAND flash memory. It has been known that when heavy metal ions come into contact with silicon crystals, they can diffuse within the crystal and reach the circuit surface, causing operational malfunctions. To prevent operational malfunctions, gettering treatment is typically performed on silicon wafers during semiconductor package assembly to capture heavy metal ions and prevent them from diffusing to the circuit surface.

[0004] The main gettering processes used today include intrinsic gettering (IG), which involves providing a gettering layer inside the wafer, and extrinsic gettering (EG), which involves providing a gettering layer on the backside of the wafer. However, with IG, the thickness of the internal gettering layer is reduced due to the trend toward thinner chips, making its effectiveness insufficient. Furthermore, EG creates microcracks on the backside of the wafer, reducing the die strength of the chip. Therefore, excessive gettering is difficult to achieve, especially with ultrathin wafers, which are difficult to handle. Given these circumstances, efforts have been made to impart gettering functionality for capturing heavy metal ions to resin films (adhesive films used in semiconductor device manufacturing processes), more specifically, to adhesive films (die-bonding films) used to bond chips to substrates or between chips themselves (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-213878 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-241157 [Non-patent literature]

[0006] [Non-Patent Document 1] Kazuhiko Ishikiriyama, Minoru Toki, Netsu Sokutei,14(3),1987. Summary of the Invention [Problem to be solved by the invention]

[0007] However, when determining whether a resin film (an adhesive film used in the manufacturing process of a semiconductor device) has a gettering function, it is necessary to actually fabricate a package using a substrate on which a wiring layer is formed or a wafer on which a circuit is formed, and then evaluate the package, which requires a large amount of cost, time, and labor.

[0008] One of the mechanisms by which the gettering function is realized is assumed to be that minute cracks, i.e., voids or defects, as in the case of EG, trap heavy metal ions. Therefore, in order to evaluate the manifestation of the gettering function in a resin film, it is considered effective to obtain information about the voids in the resin film. However, because resin films are thin and have low strength, there is currently no well-established method for measuring the voids in resin films.

[0009] The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide a novel method for evaluating the heavy metal ion permeability of a resin film. [Means for solving the problem]

[0010] The inventors have found that a method based on the principles of thermoporometry, which can evaluate the properties of water confined in voids in a hydrated resin film using the widely used differential scanning calorimetry (DSC), is an effective method for obtaining information about the voids in a resin film. Generally, water confined in voids (pore water) tends to have a lower melting point than unconfined water (bulk water). Furthermore, the stronger the water confinement, i.e., the smaller the void size, the greater the drop in melting point. This method is based on the principles of thermoporometry to obtain information about the voids in a resin film. Further investigations by the inventors have revealed that the integral value of the heat flow correlated with the heat of fusion of pore water present in the voids of a resin film, as determined by a thermoporometry-based method, can indirectly determine the permeability of heavy metal ions that pass through the resin film in a hydrated state. This led to the completion of the presently disclosed invention.

[0011] One aspect of the present disclosure relates to a method for evaluating the heavy metal ion permeability of a resin film, which includes a first step of determining an integral value of heat flow correlated with the heat of fusion of pore water present in pores of the resin film by a thermoporometry-based technique, and a second step of evaluating the heavy metal ion permeability of the resin film based on the integral value of heat flow.

[0012] The evaluation method may use, in the second step, for example, an evaluation criterion as to whether or not the integrated value of heat flow from -60°C to -5°C per 1 mg of resin film is 1.7 mW·°C / mg or more.

[0013] It is known that the melting point depression ΔT and pore radius R are related by the following formula (1) (see, for example, Non-Patent Document 1). Based on this formula, the integrated value of the heat flow from -60°C to -5°C is considered to correspond to the heat of fusion of water (pore water) present in pores with a pore radius of 5 nm or less in the resin film. The integrated value of the heat flow from 0°C to high temperatures is considered to correspond to the heat of fusion of unconstrained water (bulk water) present in macroscopic pores on the surface or inside the resin film.

[0014]

number

[0015] According to the studies of the present inventors, it was found that in a resin film, the integrated value of the heat flow from -60°C to -5°C is 1.7 mW·°C / mg or more, that is, the greater the proportion of pores with a pore radius of 5 nm or less per 1 mg of resin film, the lower the permeability of heavy metal ions and the like that permeate the resin film in a hydrated state. The reason for this tendency is not entirely clear, but the present inventors believe that it is because pores with a pore radius of 5 nm or less correspond to the size of ionic substances, hydrated substances, and the presence of many such pores in a resin film enhances the barrier properties against the diffusion of ionic substances, hydrated substances, and the like.

[0016] The resin film may be an adhesive film used in the manufacturing process of a semiconductor device, more specifically, an adhesive film (die bonding film) used for bonding between a chip and a substrate or between chips.

[0017] Another aspect of the present disclosure relates to an adhesive film used in a semiconductor device manufacturing process, in which the integrated value of heat flow per 1 mg of adhesive film from −60°C to −5°C, which is correlated with the heat of fusion of pore water present in pores of the adhesive film as determined by a thermoporometry-based technique, is 1.7 mW·°C / mg or more. [Effects of the Invention]

[0018] The present disclosure provides a novel method for evaluating the heavy metal ion permeability of a resin film, and an adhesive film for use in a semiconductor device manufacturing process based on such an evaluation method. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a DSC curve showing the change in heat flow with respect to the measurement temperature in the resin film of Production Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings, but the present disclosure is not limited to the following embodiments.

[0021] In this specification, a numerical range indicated with "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. Furthermore, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the Examples. Furthermore, the upper and lower limits individually described can be arbitrarily combined. Furthermore, in this specification, "(meth)acrylate" means at least one of acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acryloyl" and "(meth)acrylic acid." Furthermore, "(poly)" refers to both the presence and absence of the "poly" prefix. Furthermore, "A or B" may include either A or B, or may include both. Furthermore, the materials exemplified below may be used alone or in combination of two or more, unless otherwise specified. When a composition contains multiple substances corresponding to each component, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0022] [Method for evaluating heavy metal ion permeability of resin film] A method for evaluating heavy metal ion permeability of a resin film according to one embodiment includes at least a first step and a second step.

[0023] <First step> This step is a step of determining the integral of heat flow, which correlates with the heat of fusion of pore water present in the voids of the resin film, using a technique based on thermoporometry. Here, the integral of heat flow may be the temperature integral of heat flow (mW·°C). The integral of heat flow may be the integral (J) obtained by converting the temperature integral of heat flow (mW·°C) into time. This step may include, for example, immersing the resin film to be measured in water to absorb water into the resin film to obtain a water-containing resin film (step A), performing low-temperature differential scanning calorimetry (DSC) on the water-containing resin film to obtain a DSC curve showing the change in heat flow with the measurement temperature (step B), and determining the integral of heat flow, which correlates with the heat of fusion of pore water present in the voids of the resin film, based on the obtained DSC curve (step C).

[0024] (Process A) In step A, a resin film to be measured is immersed in water to allow the resin film to absorb water, thereby obtaining a water-containing resin film, thereby preparing a sample for low-temperature DSC measurement.

[0025] The resin film to be measured is not particularly limited as long as it is solid and can maintain its shape at room temperature (25° C.) In DSC measurement, the resin film needs to be moistened by absorbing water, and therefore, it is preferable that the resin film absorbs sufficient water when left standing in water for 24 hours.

[0026] The resin film may be an adhesive film used in the manufacturing process of a semiconductor device, more specifically, an adhesive film (die bonding film) used for bonding between a chip and a substrate or between chips.

[0027] The resin film (die-bonding film) may be capable of passing through a semi-cured (B-stage) state and then becoming fully cured (C-stage) after a curing treatment. The resin film (die-bonding film) may contain a thermosetting resin, a curing agent, and an acrylic rubber. The resin film (die-bonding film) may further contain a filler, a coupling agent, and a curing accelerator.

[0028] The thermosetting resin may be an epoxy resin. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, stilbene type epoxy resin, triazine skeleton-containing epoxy resin, fluorene skeleton-containing epoxy resin, triphenolmethane type epoxy resin, biphenyl type epoxy resin, xylylene type epoxy resin, biphenyl aralkyl type epoxy resin, naphthalene type epoxy resin, polyfunctional phenols, and diglycidyl ether compounds of polycyclic aromatics such as anthracene.

[0029] When the thermosetting resin is an epoxy resin, the curing agent may be an epoxy resin curing agent. The epoxy resin curing agent may be a phenolic resin. The phenolic resin may be a polycondensation product of phenol or its derivative with an aldehyde. The polycondensation is usually carried out in the presence of a catalyst such as an acid or a base. Phenolic resins obtained using an acid catalyst are particularly called novolac phenolic resins. Examples of novolac phenolic resins include phenol / formaldehyde novolac resins, cresol / formaldehyde novolac resins, xylenol / formaldehyde novolac resins, resorcinol / formaldehyde novolac resins, and phenol-naphthol / formaldehyde novolac resins.

[0030] The total content of the thermosetting resin and the curing agent may be 5 to 50 parts by mass, 7 to 40 parts by mass, or 10 to 35 parts by mass relative to 100 parts by mass of the total amount of the resin film (die-bonding film).

[0031] Acrylic rubber is a rubber having structural units derived from (meth)acrylic acid esters as a main component. The content of structural units derived from (meth)acrylic acid esters in the acrylic rubber may be, for example, 70% by mass or more, 80% by mass or more, or 90% by mass or more based on the total amount of structural units constituting the acrylic rubber. The acrylic rubber may contain structural units derived from (meth)acrylic acid esters having crosslinkable functional groups such as epoxy groups, alcoholic or phenolic hydroxyl groups, and carboxyl groups. The acrylic rubber may contain structural units derived from acrylonitrile, but it is preferable that they do not contain such units.

[0032] The content of the acrylic rubber may be 50 to 95 parts by mass, 55 to 90 parts by mass, or 60 to 85 parts by mass relative to 100 parts by mass of the total amount of the resin film (die-bonding film).

[0033] The filler may be an inorganic filler, such as aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, boron nitride, crystalline silica, or amorphous silica.

[0034] The content of the filler may be 0.5 to 15 parts by mass relative to 100 parts by mass of the total amount of the resin film (die-bonding film).

[0035] The coupling agent may be, for example, a silane coupling agent, such as γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltrimethoxysilane.

[0036] Examples of the curing accelerator include tertiary amines, imidazoles, quaternary ammonium salts, etc. Examples of the curing accelerator include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-cyanoethyl-2-phenylimidazolium trimellitate.

[0037] The resin film (die-bonding film) may further contain other components, such as pigments, ion scavengers, and antioxidants.

[0038] The content of the coupling agent, curing accelerator, and other components may be 0 to 30 parts by mass relative to 100 parts by mass of the total amount of the resin film (die-bonding film).

[0039] The resin film is formed by molding a resin composition into a film shape. The resin film can be formed by applying the resin composition to a support film or the like. A varnish of the resin composition (resin varnish) may be used to form the resin film. When using an adhesive varnish, the components are mixed or kneaded in a solvent to prepare a resin varnish, and the obtained resin varnish is applied to a support film, and the solvent is removed by heating and drying to obtain a resin film.

[0040] The support film is not particularly limited as long as it can withstand the above-mentioned heat drying, and may be, for example, a polyethylene terephthalate film. The surface of the support film may be treated with a silicone-based, silica-based, or other release agent. The thickness of the support film may be, for example, 10 to 200 μm or 20 to 170 μm.

[0041] The mixing or kneading can be carried out using a dispersing machine such as a conventional stirrer, a mortar and pestle, a three-roll mill, or a ball mill, and by appropriately combining these.

[0042] The solvent used in preparing the resin varnish is not limited as long as it can uniformly dissolve, knead, or disperse each component, and any conventionally known solvent can be used. Examples of such solvents include ketone solvents such as methyl ethyl ketone and cyclohexanone.

[0043] The resin varnish can be applied to the support film by any known method, such as knife coating, roll coating, spray coating, gravure coating, bar coating, or curtain coating.

[0044] The water in which the resin film to be measured is immersed preferably does not contain ionic substances, and may be, for example, pure water, distilled water, or the like.

[0045] The conditions for immersing the resin film to be measured in water are not particularly limited as long as the resin film can be sufficiently saturated with water, but it is preferable to leave it in water for, for example, 24 hours. If the resin film floats when left in water, it is necessary to take measures such as placing the resin film between meshes adjusted to maintain space and immersing it in water. The temperature condition for immersing the resin film to be measured in water may be around room temperature (25°C).

[0046] (Process B) In step B, low-temperature DSC measurement was performed on the water-containing resin film, and the heat flow (dq / dt (mJ s -1 )) to obtain a DSC curve showing the change in

[0047] The resin film immersed in water in step A is pulled out, and water droplets on the surface are lightly wiped off to obtain a hydrous resin film. The obtained hydrous resin film is extracted so that it fits into an aluminum pan or the like for low-temperature DSC measurement, and a sample for low-temperature DSC measurement can be prepared by spreading it until a predetermined mass is reached. In the sample for low-temperature DSC measurement, the mass of the hydrous resin film can be set arbitrarily according to the measurement conditions, measurement device, etc., and can be, for example, approximately 30 mg. Since the aluminum pan for low-temperature DSC measurement is used for measurement at low temperatures (for example, temperatures from -60°C to 25°C), it is preferable not to cover the aluminum pan with a lid or the like unless the generation of volatile components is expected. Furthermore, when performing low-temperature DSC measurement, it is preferable to take measures to prevent excessive pressure from being applied to the hydrous resin film from above.

[0048] Low-temperature DSC measurements can be performed using a commercially available differential scanning calorimeter. The temperature conditions for low-temperature DSC measurements can be, for example, cooling to -60°C, holding at -60°C for 10 minutes, and then heating to 25°C at a heating rate of 2°C / min.

[0049] The cooling device can be the one attached to the differential scanning calorimeter. The cooling method is not particularly limited as long as it can maintain -60°C for 10 minutes or more and maintain a constant heating rate, but examples include a method in which liquid nitrogen is pumped to cool the sample chamber to -60°C, or a method in which a cooling unit is installed on top and the sample is cooled to -60°C using acetone and dry ice.

[0050] The measurement atmosphere in low-temperature DSC measurement can be, for example, an air atmosphere.

[0051] By performing low-temperature DSC measurements in this manner, a DSC curve can be obtained that shows the change in heat flow versus the measurement temperature.

[0052] (Process C) In step C, the integral value of the heat flow, which correlates with the heat of fusion of the pore water present in the pores of the resin film, is determined based on the obtained DSC curve. The integral value of the heat flow in a predetermined temperature range correlates with the heat of fusion of the pore water present in pores of a predetermined pore radius in the resin film. Therefore, information about the pores of the resin film can be obtained based on the integral value of the heat flow.

[0053] <Second process> This step is a step of evaluating the heavy metal ion permeability of a resin film based on the integrated value of heat flow. According to the studies of the present inventors, it has been found that the permeability of heavy metal ions passing through a resin film in a hydrated state can be indirectly grasped based on the integrated value of heat flow, which correlates with the heat of fusion of pore water present in the pores of the resin film, determined by a technique based on thermoporometry.

[0054] In this step, for example, the evaluation criterion may be whether or not the integral value of heat flow from −60° C. to −5° C. per 1 mg of resin film is 1.7 mW·° C. / mg or more.

[0055] As mentioned above, it is estimated that the integrated value of the heat flow from -60°C to -5°C per 1 mg of resin film corresponds to the heat of fusion of the water (pore water) present in the pores in the resin film with a pore radius of 5 nm or less.

[0056] The integrated value of the heat flow from -60°C to -5°C per 1 mg of resin film may be 1.7 mW·°C / mg or more, for example, 1.8 mW·°C / mg or more, 2.0 mW·°C / mg or more, 2.3 mW·°C / mg or more, or 2.5 mW·°C / mg or more. According to the inventors' studies, resin films evaluated as having an integrated value of the heat flow of 1.7 mW·°C / mg or more tend to have low permeability to heavy metal ions and the like that permeate the resin film in a hydrated state. While the reason for this tendency is not entirely clear, the inventors believe that it is because pores with a pore radius of 5 nm or less correspond to the size of ionic substances, hydrated substances, and the like, and thus the presence of many such pores in a resin film enhances the barrier properties against the diffusion of ionic substances, hydrated substances, and the like. The upper limit of the integrated value of the heat flow is not particularly limited, but can be, for example, 10.0 mW·°C / mg or less.

[0057] [Adhesive film] In one embodiment, the adhesive film used in the manufacturing process of a semiconductor device has an integrated heat flow value correlated to the heat of fusion of pore water present in the voids of the adhesive film, as determined by a technique based on thermoporometry, of 1.7 mW·°C / mg or more from -60°C to -5°C per 1 mg of adhesive film.

[0058] Preferred aspects of the types, contents, etc. of the constituent components of the adhesive film are the same as the preferred aspects of the types, contents, etc. of the constituent components of the resin film in the above evaluation method. Also, preferred aspects of the integrated value of heat flow from -60°C to -5°C per 1 mg of adhesive film are the same as the preferred aspects of the integrated value of heat flow from -60°C to -5°C per 1 mg of resin film in the above evaluation method. Therefore, redundant explanations will be omitted here. [Example]

[0059] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to these examples.

[0060] [Preparation of resin film] (Production Example 1) 12 parts by mass of YDCN-700-10 (trade name, manufactured by Nippon Steel Chemical & Material Co., Ltd., cresol novolac epoxy resin, epoxy equivalent: 209 g / eq) as a thermosetting resin, 10 parts by mass of HE-100C-30 (trade name, manufactured by Air Water Inc., phenol novolac phenolic resin, hydroxyl group equivalent: 174 g / eq, softening point: 77°C) as a curing agent, 0.5 parts by mass of A-189 (trade name, manufactured by Momentive Performance Materials Japan LLC, γ-mercaptopropyltrimethoxysilane) as a coupling agent, A composition consisting of 1.2 parts by mass of A-1160 (trade name, manufactured by Momentive Performance Materials Japan, LLC, γ-ureidopropyltriethoxysilane) and 9 parts by mass of Aerosil R972 (trade name, manufactured by Nippon Aerosil Co., Ltd., a filler having organic groups such as methyl groups on the surface, formed by treating the silica surface with dimethyldichlorosilane and hydrolyzing it in a reactor at 400°C, average particle size: 0.016 μm, agglomerated filler) was added to cyclohexanone and mixed with stirring, and then kneaded for 90 minutes using a bead mill to obtain a kneaded product.

[0061] Next, 68 parts by mass of high-purity SG-P3 (product name SG-P3, manufactured by Nagase ChemteX Corporation, weight-average molecular weight: 800,000, theoretical Tg: 12°C) and 0.05 parts by mass of Curesol 2PZ-CN (product name, manufactured by Shikoku Chemicals Corporation, 1-cyanoethyl-2-phenylimidazole) as a curing accelerator were added to the kneaded product, and the mixture was stirred and mixed, followed by vacuum degassing to obtain a varnish of a resin composition.

[0062] The varnish was applied to a 35 μm thick release-treated polyethylene terephthalate film as a support film, and the film was dried by heating at 140°C for 5 minutes to produce a resin film of Production Example 1 having a thickness of 10 μm and in a B-stage state.

[0063] (Production Example 2) A resin film of Production Example 2 having a thickness of 10 μm and in a B-stage state was produced in the same manner as Production Example 1, except that the components and their contents used in Production Example 1 were changed to the components and their contents shown in Production Example 2 in Table 1.

[0064] (Production Example 3) A resin film of Production Example 3 having a thickness of 10 μm and in a B-stage state was produced in the same manner as Production Example 1, except that the components and their contents used in Production Example 1 were changed to the components and their contents shown in Production Example 3 in Table 1.

[0065] [Table 1]

[0066] Among the materials in Table 1, the materials not shown in Production Example 1 are as follows. (hardening agent) MEH-5100-5S (product name, manufactured by Meiwa Chemical Co., Ltd., phenol novolac type phenolic resin, hydroxyl group equivalent: 116 g / eq, softening point: 65°C) (acrylic rubber) Improved high-purity SG-P3 (product name SG-P3, Nagase ChemteX Corporation acrylic rubber with acrylonitrile-derived structural units removed, weight-average molecular weight: 600,000, theoretical Tg: 12°C) (filler) SC2050-HLG (product name, manufactured by Admatechs Co., Ltd., spherical silica, average particle size: 0.5 μm)

[0067] [Evaluation of resin film] (Examples 1 and 2, Comparative Example 1) <Evaluation using thermoporometry-based methods> A thermoporometry-based technique was investigated using the resin films of Production Examples 1 to 3 in the B-stage state. The resin film was placed in a stainless steel mesh container, immersed in distilled water, and left to stand for 24 hours. The stainless steel container was then removed, and the water droplets on the surface were wiped off to obtain a hydrous resin film. A sample was immediately cut out with a φ4 mm punch and placed in an aluminum pan GAA-0068 (Hitachi High-Tech Science Corporation, AI open-type sample container φ5.2H2.5 mm) to a mass of 30 mg to obtain a sample for low-temperature DSC measurement. The obtained sample was placed in a sample holder without a lid.

[0068] Next, low-temperature DSC measurements were performed using a differential scanning calorimeter (Thermoplus Evo DSC 8230, manufactured by Rigaku Corporation). The samples were cooled to -60°C using an attached cooling unit and acetone and dry ice. The cooling and heating program consisted of cooling to -60°C, holding at -60°C, and then heating to 25°C at a rate of 2°C / min. The measurement atmosphere was air. Low-temperature DSC measurements were performed under these conditions, and DSC curves showing the change in heat flow versus measurement temperature were obtained for each of the resin films of Production Examples 1 to 3.

[0069] FIG. 1 is a DSC curve showing the change in heat flow versus measurement temperature for the resin film of Production Example 1. In FIG. 1, the integrated value of heat flow from -60°C to -5°C corresponds to region A. Based on this, the integrated value of heat flow per 1 mg from -60°C to -5°C for the resin film of Production Example 1 was calculated. Similarly, the integrated value of heat flow per 1 mg from -60°C to -5°C for the resin films of Production Examples 2 and 3 was calculated. The results are shown in Table 2.

[0070] <Heavy metal ion (copper ion) permeability test> (Preparation of Solution A) 2.0 g of anhydrous copper (II) sulfate was dissolved in 1020 g of distilled water and stirred until the copper sulfate was completely dissolved to prepare an aqueous solution of copper sulfate with a copper ion concentration of 500 mg / kg in elemental Cu equivalent. The resulting aqueous solution of copper sulfate was designated as Solution A.

[0071] (Preparation of Solution B) 1.0 g of anhydrous sodium sulfate was dissolved in 1000 g of distilled water and stirred until the sodium sulfate was completely dissolved. 1000 g of N-methyl-2-pyrrolidone (NMP) was added and stirred. The mixture was then air-cooled to room temperature to obtain an aqueous sodium sulfate solution. The resulting solution was designated as Solution B.

[0072] (Measurement of copper ion permeation time) Each of the resin films from Production Examples 1 to 3 in the B-stage state was cut into a circle with a diameter of approximately 3 cm. Next, two silicone packing sheets with a thickness of 1.5 mm, an outer diameter of approximately 3 cm, and an inner diameter of 1.8 cm were prepared. The resin film circle cut out was sandwiched between the two silicone packing sheets, and this was then sandwiched between the flanges of two glass cells with a volume of 50 mL and secured in place with rubber bands.

[0073] Next, 50 g of Solution A was poured into one glass cell, followed by 50 g of Solution B into the other glass cell. Mars Carbon (2 mm diameter, 130 mm diameter, manufactured by Staedtler GmbH) carbon electrodes were inserted into each cell. The Solution A side served as the anode, and the Solution B side served as the cathode. The anode was connected to a DC power supply (AD-9723D DC power supply, manufactured by A&D Co., Ltd.). The cathode and DC power supply were connected in series via an ammeter (PC-720M Digital Multimeter, manufactured by Sanwa Electric Instruments Co., Ltd.). A voltage of 24.0 V was applied at room temperature (25°C), and current measurement began after the application. Measurement was continued until the current value exceeded 15 μA, and the time when the current value reached 10 μA was defined as the copper ion permeation time. The longer the copper ion permeation time, the more difficult it was for copper ions to permeate the resin film, indicating that the resin film had excellent permeability to heavy metal ions. The copper ion permeation time was evaluated as "A" when it was 200 minutes or more, "B" when it was 50 minutes or more but less than 200 minutes, and "C" when it was less than 50 minutes. The results are shown in Table 2.

[0074] [Table 2]

[0075] As shown in Table 2, in the thermoporometry-based method, the resin films of Production Examples 1 and 2 met the requirement of 1.7 mW·°C / mg or more for the integral value of heat flow per 1 mg from -60°C to -5°C. In the heavy metal ion (copper ion) permeability test, the resin films of Production Examples 1 and 2 sufficiently suppressed copper ion permeation. In contrast, the resin film of Production Example 3 did not meet the requirement of 1.7 mW·°C / mg or more for the integral value of heat flow per 1 mg from -60°C to -5°C. Therefore, the permeability of copper ions was not sufficiently suppressed in the heavy metal ion (copper ion) permeability test. In a resin film, a heat flow integral value of 1.7 mW·°C / mg or more per 1 mg from -60°C to -5°C indicates a high proportion of pores with a pore radius of 5 nm or less. These results confirm that the heavy metal ion permeability of a resin film can be evaluated by evaluating the proportion of pores with a pore radius of 5 nm or less.

Claims

1. a first step of determining an integral value of heat flow correlated with the heat of fusion of pore water present in voids of a resin film by a technique based on thermoporometry; a second step of evaluating the heavy metal ion permeability of the resin film based on the integrated value of the heat flow; Equipped with Method for evaluating heavy metal ion permeability of resin films.

2. In the second step, the evaluation criterion is whether or not an integrated value of heat flow per 1 mg of the resin film from −60° C. to −5° C. is 1.7 mW° C. / mg or more. The evaluation method according to claim 1 .

3. The resin film is an adhesive film used in the manufacturing process of a semiconductor device. The evaluation method according to claim 1 or 2.

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