JP7757672B2 - Method for evaluating heavy metal ion permeability of resin films and adhesive films - Google Patents

Description

This disclosure relates to a method for evaluating the heavy metal ion permeability of a resin film and an adhesive film.

In recent years, as smartphones, tablet PCs, and other devices have become more functional and faster, the semiconductor packages used in them are being required to be even smaller, have higher capacity, are faster, and are thinner. 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.

Amid this trend, problems are beginning to emerge, particularly in the fields of DRAM and NAND flash memory, where trace amounts of heavy metal ions, such as copper ions, can cause operational malfunctions. 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 is typically performed during semiconductor package assembly to capture heavy metal ions on the silicon wafer so that they do not diffuse to the circuit surface.

The two most commonly used gettering methods are intrinsic gettering (IG), which creates a gettering layer inside the wafer, and extrinsic gettering (EG), which creates 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, with EG, microcracks are formed on the backside of the wafer, reducing the die strength of the chip. This makes excessive gettering difficult to perform, particularly on ultra-thin wafers, which are difficult to handle. Given these circumstances, research has been conducted into the addition of gettering functionality to resin films (adhesive films used in semiconductor device manufacturing processes), specifically adhesive films (die-bonding films) used to bond chips to substrates or between chips themselves (see, for example, Patent Documents 1 and 2).

JP 2011-213878 A JP 2012-241157 A

Kazuhiko Ishikiriyama, Minoru Toki, Netsu Sokutei, 14(3), 1987.

However, when determining whether a resin film (an adhesive film used in the manufacturing process of semiconductor devices) has gettering properties, it is necessary to actually fabricate a package using a substrate with a wiring layer formed thereon or a wafer with a circuit formed thereon, and then evaluate it. This requires a great deal of money, time, and effort.

One of the mechanisms by which gettering function is thought to occur is that tiny cracks, such as those in EG above, i.e., voids or defects, trap heavy metal ions. Therefore, in order to evaluate the occurrence of gettering function in a resin film, it is thought to be effective to obtain information about the voids in the resin film. However, because resin films are thin and have low strength, the current situation is that there are no fully established methods for measuring voids in resin films that are suitable for this purpose.

This disclosure was made in light of these circumstances, and its main purpose is to provide a novel method for evaluating the heavy metal ion permeability of resin films.

The inventors' research has revealed that a method based on the principles of thermoporometry, which can evaluate the properties of water confined in voids in hydrated resin films using the widely used differential scanning calorimetry (DSC), is an effective method for obtaining information about the voids in resin films. In general, water confined in voids (pore water) tends to have a lower melting point than unconfined water (bulk water). Furthermore, the stronger the water confinement, in other words, the smaller the void size, the greater the drop in melting point tends to be. This method, based on the principles of thermoporometry, is a method for obtaining information about the voids in resin films. After further investigation, the inventors discovered that the permeability of heavy metal ions that pass through a resin film in a hydrated state can be indirectly determined based on the integral value of heat flow, which correlates with the heat of fusion of pore water present in the voids of the resin film, determined using a technique based on thermoporometry, and thus completed the disclosed invention.

One aspect of the present disclosure relates to a method for evaluating the heavy metal ion permeability of a resin film. The evaluation method includes a first step of determining, using a thermoporometry-based technique, an integral value of heat flow that correlates with the heat of fusion of pore water present in the voids of the resin film, and a second step of evaluating the heavy metal ion permeability of the resin film based on the integral value of heat flow.

In the second step, the evaluation method may use, for example, whether the integrated value of heat flow per 1 mg of resin film from -60°C to -5°C is 1.7 mW·°C/mg or more as an evaluation criterion.

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 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. Furthermore, the integrated value of heat flow from 0°C to high temperatures is considered to correspond to the heat of fusion of unbound water (bulk water) present in macroscopic pores on the surface or inside the resin film.

The inventors' studies have revealed that in resin films where the integrated value of heat flow from -60°C to -5°C is 1.7 mW·°C/mg or greater, i.e., the greater the proportion of voids with a void radius of 5 nm or less per 1 mg of resin film, the lower the permeability of heavy metal ions and other substances that permeate the resin film in a hydrated state. While the reason for this tendency is not entirely clear, the inventors believe that since voids with a void radius of 5 nm or less correspond to the size of ionic substances, hydrated substances, and the presence of many such voids in a resin film enhances the barrier properties against the diffusion of ionic substances, hydrated substances, and the like.

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

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

The present disclosure provides a novel method for evaluating the heavy metal ion permeability of a resin film. The present disclosure also provides an adhesive film based on this evaluation method for use in the manufacturing process of a semiconductor device.

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.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the following embodiments.

In this specification, numerical ranges indicated using "to" indicate ranges that include 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. Individually described upper and lower limits may be arbitrarily combined. Furthermore, in this specification, "(meth)acrylate" refers to 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 both. Furthermore, the materials exemplified below may be used alone or in combinations of two or more, unless otherwise specified. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[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.

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

(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.

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). Since DSC measurement requires the resin film to be moistened by absorbing water, it is preferable for the resin film to absorb sufficient water when left standing in water for 24 hours, for example.

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

The resin film (die-bonding film) may be capable of going through a semi-cured (B-stage) state and then becoming fully cured (C-stage) after a curing process. 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.

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

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 derivatives with aldehydes. Polycondensation is usually carried out in the presence of a catalyst such as an acid or base. Phenolic resins obtained using an acid catalyst are particularly called novolac-type phenolic resins. Examples of novolac-type phenolic resins include phenol/formaldehyde novolac resin, cresol/formaldehyde novolac resin, xylenol/formaldehyde novolac resin, resorcinol/formaldehyde novolac resin, and phenol-naphthol/formaldehyde novolac resin.

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

Acrylic rubber is a rubber whose main component is a structural unit derived from a (meth)acrylic acid ester. The content of structural units derived from a (meth)acrylic acid ester 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 a (meth)acrylic acid ester having a crosslinkable functional group such as an epoxy group, an alcoholic or phenolic hydroxyl group, or a carboxyl group. The acrylic rubber may contain structural units derived from acrylonitrile, but it is preferable that they do not contain such units.

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

The filler may be an inorganic filler. Examples of inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, boron nitride, crystalline silica, and amorphous silica.

The filler content may be 0.5 to 15 parts by mass per 100 parts by mass of the total resin film (die bonding film).

The coupling agent may be, for example, a silane coupling agent. Examples of silane coupling agents include γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltrimethoxysilane.

Examples of curing accelerators include tertiary amines, imidazoles, and quaternary ammonium salts. Examples of curing accelerators include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-cyanoethyl-2-phenylimidazolium trimellitate.

The resin film (die-bonding film) may further contain other components. Examples of other components include pigments, ion scavengers, antioxidants, etc.

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

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

The support film is not particularly limited as long as it can withstand the heat drying described above, but it 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.

Mixing or kneading can be carried out using a conventional mixer, dispersing machine such as a mixer, a three-roll mill, or a ball mill, or by combining these as appropriate.

The solvent used to prepare the resin varnish is not limited as long as it can uniformly dissolve, knead, or disperse the components, and any conventionally known solvent can be used. Examples of such solvents include ketone solvents such as methyl ethyl ketone and cyclohexanone.

The resin varnish can be applied to the support film using known methods, such as knife coating, roll coating, spray coating, gravure coating, bar coating, and curtain coating.

The water used to immerse the resin film to be measured preferably does not contain ionic substances, and may be, for example, pure water or distilled water.

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 24 hours, for example. If the resin film floats when left in water, it will be necessary to take measures such as placing the resin film between meshes adjusted to maintain space and then immersing it in water. The temperature conditions for immersing the resin film to be measured in water may be around room temperature (25°C).

(Process B)
In step B, the water-containing resin film is subjected to low-temperature DSC measurement to obtain a DSC curve showing the change in heat flow (dq/dt (mJ·s ⁻¹ )) with respect to the measurement temperature.

The resin film immersed in water in step A is removed, and the water droplets on the surface are lightly wiped off to obtain a hydrous resin film. The obtained hydrous resin film is extracted into an aluminum pan or the like for low-temperature DSC measurement, and the pan is spread until the desired mass is reached, thereby preparing a sample for low-temperature DSC measurement. The mass of the hydrous resin film in the sample for low-temperature DSC measurement can be set arbitrarily depending on 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 (e.g., temperatures between -60°C and 25°C), it is preferable not to cover the aluminum pan with a lid or other cover unless the generation of volatile components is expected. Furthermore, when performing low-temperature DSC measurement, it is preferable to take measures to avoid applying more pressure than necessary from above to the hydrous resin film.

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 rate of 2°C/min.

The cooling device that comes with the differential scanning calorimeter can be used. There are no particular restrictions on the cooling method, as long as it can maintain -60°C for 10 minutes or more and maintain a constant heating rate. Examples include pumping liquid nitrogen to cool the sample chamber to -60°C, or installing a cooling unit on top and cooling to -60°C using acetone and dry ice.

The measurement atmosphere for low-temperature DSC measurements can be, for example, an air atmosphere.

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

(Process C)
In step C, the heat flow integral, which correlates with the heat of fusion of pore water present in the pores of the resin film, is calculated based on the obtained DSC curve. The heat flow integral within a predetermined temperature range correlates with the heat of fusion of 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 heat flow integral.

<Second step>
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.

In this process, the evaluation criterion may be, for example, whether the integrated value of heat flow per 1 mg of resin film from -60°C to -5°C is 1.7 mW·°C/mg or more.

As mentioned above, the integrated value of heat flow per 1 mg of resin film from -60°C to -5°C is estimated 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 -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. The inventors' studies have found that 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 other substances that permeate the resin film in a hydrated state. While the reason for this tendency is not entirely clear, the inventors believe that pores with a pore radius of 5 nm or less correspond to the size of ionic substances, hydrated substances, and that the presence of many such pores in a resin film enhances the barrier properties against the diffusion of ionic substances, hydrated substances, and other substances. 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.

[Adhesive film]
In one embodiment, the adhesive film used in the manufacturing process of the semiconductor device has an integrated value of heat flow 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, where the integrated value of heat flow per 1 mg of adhesive film from -60°C to -5°C is 1.7 mW·°C/mg or more.

Preferred aspects of the type and content of the adhesive film's constituent components are the same as the preferred aspects of the type and content of the resin film's constituent components in the evaluation method described above. Furthermore, 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 evaluation method described above. Therefore, redundant explanations will be omitted here.

The present disclosure will be explained in more detail below using examples. However, the present disclosure is not limited to these examples.

[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 Aerosil R972 (trade name, manufactured by Nippon Aerosil Co., Ltd.; a filler having organic groups such as methyl groups on the surface, obtained by treating the silica surface with dimethyldichlorosilane and hydrolyzing it in a reactor at 400°C; average particle size: 0.016 μm; agglomerated filler) as a filler was added with cyclohexanone, stirred and mixed, and then kneaded for 90 minutes using a bead mill to obtain a kneaded product.

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 mixture, and the mixture was stirred and mixed, followed by vacuum degassing to obtain a resin composition varnish.

The varnish was applied to a 35 μm thick release-treated polyethylene terephthalate film used as a support film, and then heated and dried at 140°C for 5 minutes to produce a 10 μm thick resin film in a B-stage state (Production Example 1).

(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 contents of those components used in Production Example 1 were changed to the components and contents of those components shown in Production Example 2 in Table 1.

(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 contents of those components used in Production Example 1 were changed to the components and contents of those components shown in Production Example 3 in Table 1.

Among the materials in Table 1, the materials not shown in Production Example 1 are as follows.
(hardening agent)
MEH-5100-5S (trade name, manufactured by Meiwa Chemical Industry Co., Ltd., phenol novolac type phenolic resin, hydroxyl group equivalent: 116 g/eq, softening point: 65°C)
(acrylic rubber)
An improved version of the high-purity SG-P3 (product name: SG-P3, manufactured by Nagase ChemteX Corporation, acrylic rubber from which the structural units derived from acrylonitrile have been 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)

[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 a B-stage state. The resin film was placed in a container made of stainless steel mesh, immersed in a container containing 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.

Next, low-temperature DSC measurements were performed using a differential scanning calorimeter (Thermoplus Evo DSC 8230, manufactured by Rigaku Corporation). The attached cooling unit was used to cool the sample to -60°C using 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.

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

<Heavy metal ion (copper ion) permeability test>
(Preparation of Solution A)
2.0 g of anhydrous copper(II) sulfate was dissolved in 1,020 g of distilled water and stirred until the copper sulfate was completely dissolved to prepare an aqueous copper sulfate solution having a copper ion concentration of 500 mg/kg in terms of elemental Cu. The resulting aqueous copper sulfate solution was designated as Solution A.

(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 then 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 Liquid B.

(Measurement of copper ion permeation time)
Each of the resin films of Production Examples 1 to 3 in a 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 cut into a circle was sandwiched between the two silicone packing sheets, and this was sandwiched between the flanges of two glass cells with a volume of 50 mL and secured in place with rubber bands.

Next, 50 g of Solution A was poured into one glass cell, followed by 50 g of Solution B into the other glass cell. A carbon electrode, Mars Carbon (Staedtler GmbH, φ2 mm/130 mm), was inserted into each cell. The Solution A side was the anode, and the Solution B side was the cathode. The anode was connected to a DC power supply (A&D Co., Ltd., DC power supply AD-9723D). The cathode was also connected in series to the DC power supply via an ammeter (Sanwa Electric Instruments Co., Ltd., Digital multimeter PC-720M). A voltage of 24.0 V was applied at room temperature (25°C), and current measurement began immediately after application. Measurement 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 is for copper ions to permeate through the resin film, indicating a resin film with excellent heavy metal ion permeability. A copper ion permeation time of 200 minutes or more was rated "A," a time of 50 minutes or more but less than 200 minutes was rated "B," and a time of less than 50 minutes was rated "C." The results are shown in Table 2.

As shown in Table 2, in a study using a thermoporometry-based technique, 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 a 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, and did not sufficiently suppress copper ion permeation in the heavy metal ion (copper ion) permeability test. In a resin film, an integral value of heat flow per 1 mg from -60°C to -5°C of 1.7 mW·°C/mg or more indicates a high proportion of voids with a void radius of 5 nm or less. These results confirm that the heavy metal ion permeability of a resin film can be evaluated by assessing the proportion of voids with a void radius of 5 nm or less.

Claims (3)

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. 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 . 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.