Electronic component protective film and electronic component protective device

Abstract

To provide an electronic component protective film having dust resistance, air permeability, and heat resistance despite using a non-fluorine material.SOLUTION: An electronic component protective film according to an embodiment includes a nonwoven fabric formed of polyarylate resin nanofibers having 10 to 3000 nm of average fiber diameter. An electronic component protective device according to the embodiment has the electronic component protective film and a heat resistant double-sided adhesive sheet disposed at a peripheral edge area at least on one principal surface of the protective film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a protective film used to protect electronic components, and a protection device for electronic components including the protective film. [Background technology]

[0002] The use of dust-proof, breathable, and heat-resistant protective films has been studied to protect electronic components from, for example, dust during manufacturing processes, resist coating, and heat during reflow processes. Examples of such electronic components include microphones, speakers, and semiconductor electronic elements built into electronic devices such as mobile phones and portable music players.

[0003] It is conceivable to use a nonwoven fabric as such a protective film, but in general, nonwoven fabrics have the contradictory problem that improving dust resistance increases pressure loss and reduces breathability, and improving breathability also reduces dust resistance.

[0004] On the other hand, resin films made of polytetrafluoroethylene (PTFE) are known as heat-resistant resin films. For example, Patent Documents 1 and 2 propose uniaxially or biaxially stretched films made of porous PTFE as resin films that also have breathability. Such porous PTFE films combine excellent heat resistance, dust resistance, drip resistance, and breathability. However, the film production process requires many steps, and advanced manufacturing control technology is required to ensure stable performance, which is cost-inefficient. Furthermore, there is a recent trend in industry to avoid materials containing fluorine, a substance that has a negative impact on the environment. From this perspective, it is desirable for protective films to be made of non-fluorine materials.

[0005] Patent Document 3 proposes a porous support in the form of a nonwoven fabric made of nanofibers with an average fiber diameter of 40 to 5000 nm, which is produced by electrospinning using a polyimide precursor (polyamic acid) as a spinning material, as a heat-resistant and breathable membrane. However, Patent Document 3 does not disclose the use of the porous support to protect electronic components. Furthermore, when a polyimide precursor is used, after the nonwoven fabric is formed, a thermal curing step at 400°C or higher is required to develop the inherent heat resistance of the polyimide, which is also disadvantageous in terms of cost. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-115687 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-081881 [Patent Document 3] Patent No. 6353917 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of an embodiment of the present invention is to provide a protective film for electronic components that is made of a non-fluorine material and has dust resistance, breathability, and heat resistance. [Means for solving the problem]

[0008] The present invention includes the embodiments shown below. [1] A protective film for electronic components, comprising a nonwoven fabric of nanofibers of polyarylate resin having an average fiber diameter of 10 to 3000 nm. [2] The protective film for electronic components according to [1], wherein the nonwoven fabric has an average pore size of 1 to 500 nm. [3] The mass per unit area of ​​the nonwoven fabric is 0.1 to 20 g / m 2 The protective film for electronic components according to [1] or [2], [4] The protective film for electronic components according to any one of [1] to [3], wherein the polyarylate resin has a glass transition point of 230 to 300°C. [5] The protective film for electronic components according to any one of [1] to [4], wherein the nonwoven fabric is an electrospun nonwoven fabric. [6] The protective film for electronic components according to any one of [1] to [5], which is used to protect electronic components at least in a solder reflow process. [7] A protective device for electronic components, comprising: a protective film for electronic components according to any one of [1] to [6]; and a heat-resistant double-sided pressure-sensitive adhesive sheet disposed in a peripheral region on at least one main surface of the protective film. [Effects of the Invention]

[0009] According to this embodiment, it is possible to provide a protective film for electronic components that is dustproof, breathable, and heat-resistant while using a non-fluorine material. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of an electronic component protection device including a protective film for electronic components according to one embodiment; [Figure 2] A plan view of the protection device for electronic components [Figure 3] FIG. 1 is a diagram illustrating a method for a sound permeability test. DETAILED DESCRIPTION OF THE INVENTION

[0011] The protective film for electronic components according to this embodiment (hereinafter simply referred to as the protective film) includes a nonwoven fabric formed from nanofibers of polyarylate resin having an average fiber diameter of 10 to 3000 nm. Polyarylate resin is a fluorine-free resin and has excellent heat resistance. By forming a nonwoven fabric using such polyarylate resin as nanofibers having an average fiber diameter of 10 to 3000 nm, a film having a three-dimensional microporous structure can be formed. Therefore, a protective film that is excellent in heat resistance and combines dust resistance and breathability can be obtained while using a non-fluorine material. In this specification, the term "nano" refers to the nanoscale and includes sizes of 3000 nm or less. Therefore, the concept of "nanofibers" also includes those having an average fiber diameter of 3000 nm or less.

[0012] Polyarylate resins are thermoplastic aromatic polyester resins made from a polycondensation product of a dihydric phenol and a dibasic acid, and have excellent heat resistance. The dihydric phenol is preferably a bisphenol such as bisphenol A. The dibasic acid is preferably an aromatic dicarboxylic acid such as phthalic acid (e.g., isophthalic acid, terephthalic acid). In one embodiment, the polyarylate resin is preferably a polycondensation product of a dihydric phenol, including bisphenol A, and phthalic acid.

[0013] Polyarylate resins having a glass transition point (Tg) of 190°C or higher are preferably used. For example, Unitika Ltd.'s "U Polymer U-100" is a polycondensate of bisphenol A and terephthalic acid / isophthalic acid, and has a glass transition point of 193°C. Unitika Ltd.'s "Unifiner" is a polyarylate resin obtained by appropriately selecting a dihydric phenol based on the structure of "U-100." Commercially available products include "M-2040," "M-2040H," and "M-2000H." Among these, "M-2040" has a glass transition point of 220°C, "M-2040H" has a glass transition point of 235°C, and "M-2000H" has a glass transition point of 275°C. From the viewpoint of further increasing the heat resistance, the polyarylate resin preferably has a glass transition point of 230 to 300°C, and even more preferably 250 to 290°C.

[0014] In this specification, the glass transition temperature is measured in accordance with JIS K7121-1987.

[0015] The average fiber diameter of nanofibers made of polyarylate resin is, as described above, 10 to 3000 nm, more preferably 10 to 1700 nm, more preferably 10 to 1500 nm, more preferably 10 to 1200 nm, more preferably 10 to 1000 nm, more preferably 100 to 1000 nm, more preferably 300 to 950 nm, more preferably 400 to 900 nm, and more preferably 500 to 900 nm. The method for measuring the average fiber diameter is as described in the Examples section.

[0016] The nanofiber nonwoven fabric made of such a polyarylate resin preferably has an average pore size of 1 to 500 nm. By providing such a pore size, high collection performance for nano- to micron-order fine particles can be achieved, and dustproofness can be improved. The average pore size is more preferably 10 to 300 nm, and even more preferably 50 to 200 nm. The method for measuring the average pore size is as described in the Examples section.

[0017] The nanofiber nonwoven fabric has a mass per unit area (also referred to as surface density) of 0.1 to 20 g / m 2 By setting the surface density in this range, in combination with the above-mentioned settings of the average fiber diameter and average pore diameter, it is possible to enhance the effect of achieving both dust resistance and breathability. The surface density is more preferably 0.5 to 15 g / m 2 and more preferably 1.0 to 10 g / m 2 and more preferably 3 to 8 g / m 2 The method for measuring the areal density is as described in the Examples section.

[0018] The thickness of the nanofiber nonwoven fabric is not particularly limited, but is preferably 5 to 500 μm, more preferably 10 to 300 μm, and even more preferably 30 to 200 μm.

[0019] The method for obtaining the nanofiber nonwoven fabric is not particularly limited. The nanofiber nonwoven fabric may be, for example, an electrospun nonwoven fabric produced by an electrospinning method, a centrifugal spun nonwoven fabric produced by a centrifugal spinning method, or a meltblown nonwoven fabric produced by a meltblown method. Among these, electrospun nonwoven fabrics produced by electrospinning methods such as electrospinning and electroblowing are more preferred. This is because electrospun nonwoven fabrics can be easily made into nanofibers, and the nonwoven fabric itself can easily achieve dust resistance and breathability against nano- to micron-order particles.

[0020] Electrospinning is a technique for electrically spinning ultrafine fibers. A high voltage is applied to a polymer solution, etc., and the solution is stretched, split, and refined by the repulsive electrostatic force, resulting in ultrafine fibers. Using this electrospinning method, nanofibers made of polyarylate resin are deposited on the surface of a smooth substrate. This allows the formation of a nanofiber fiber assembly layer, and a nanofiber nonwoven fabric made of this fiber assembly layer can be obtained.

[0021] Electrospun nonwoven fabrics can be obtained using known electrospinning methods. For example, electrospinning uses an apparatus equipped with a syringe with a spinning capillary, a high-voltage source, and a conductive collector (target substrate). The syringe is filled with a polyarylate resin solution, which is the raw material for the nanofibers. With a voltage applied between the syringe and the conductive collector, the resin solution in the syringe is gradually pushed in and extruded from the tip of the capillary. The solvent in the extruded solution evaporates, and the polyarylate resin, which is the solute, solidifies and elongates and deforms due to the potential difference, forming nanofibers, which are then deposited on the conductive collector. The electrospinning method is not particularly limited, and examples include a needle method, an air blow method, and a multi-hole spinneret method.

[0022] In the above electrospinning method, the average fiber diameter, average pore diameter and areal density can be adjusted by appropriately setting the concentration of the polyarylate resin solution, the discharge speed, the applied voltage and the collector transport speed.

[0023] There are no particular restrictions on the breathability of the nanofiber nonwoven fabric made of polyarylate resin. 3 / (cm 2 s), and more preferably 20 to 40 cm 3 / (cm 2 The method for measuring the air permeability is as described in the Examples section.

[0024] The tensile strength of the nanofiber nonwoven fabric is not particularly limited, and may be, for example, 0.5 to 10 N / mm 2 1.0~5.0N / mm 2 The tensile elongation is not particularly limited either and may be, for example, 5 to 30%, 7 to 30%, or 10 to 20%. The methods for measuring tensile strength and elongation are as described in the Examples section.

[0025] The protective film according to this embodiment may consist solely of the nanofiber nonwoven fabric, or may comprise the nanofiber nonwoven fabric together with other components such as a support. The nanofiber nonwoven fabric may consist solely of polyarylate resin, or may contain optional components such as a colorant, an ultraviolet stabilizer, an anti-fatigue agent, an anti-wear agent, and a heat-resistant agent.

[0026] The electronic component protection device (hereinafter simply referred to as the protection device) according to this embodiment is a device, i.e., a protective instrument, used to protect electronic components. The protection device includes the above-described protective film and a heat-resistant double-sided pressure-sensitive adhesive sheet disposed in a peripheral region on at least one main surface of the protective film. Here, the main surface refers to the planar front and back surfaces of the protective film.

[0027] A heat-resistant double-sided pressure-sensitive adhesive sheet is a sheet in which heat-resistant adhesive layers are provided on both sides of a heat-resistant substrate, and has adhesive properties on both sides to fix the protective film to other components. The heat-resistant substrate can be a heat-resistant resin film, such as a polyimide film or an aramid film. The heat-resistant adhesive layer can be formed by applying, for example, a silicone-based adhesive or an acrylic-based adhesive.

[0028] 1 and 2 are diagrams showing an example of a protective device 1. A heat-resistant double-sided adhesive sheet 3 is provided on one side of a disk-shaped protective film 2. The heat-resistant double-sided adhesive sheet 3 is ring-shaped and is provided around the entire periphery of one side of the protective film 2. A circular protective film region 4 is provided inside the heat-resistant double-sided adhesive sheet 3, which ensures breathability while exhibiting dustproof performance.

[0029] Such a protective device can be manufactured as follows. For example, a heat-resistant double-sided pressure-sensitive adhesive sheet having a plurality of openings is attached to a nanofiber nonwoven fabric formed by electrospinning. Next, a circle is punched out so as to surround the outside of each opening. This completes the protective device.

[0030] The protective film or protective device according to this embodiment is used to protect electronic components built into electronic devices, and may provide protection during the manufacturing process or at the product stage after manufacture.

[0031] Preferably, the protective film or protective device is used to protect electronic components from dust during the manufacturing process, resist application, and / or heat during the reflow process. In this case, the protective film or protective device may be used only during the manufacturing process of the electronic device, and therefore may be removed after manufacturing and not remain in the product. Alternatively, the protective film or protective device may function as a protective film not only during the manufacturing process of the electronic device but also after the product is completed, and therefore may remain in the product to protect the electronic components from dust, water droplets, etc. when the product is in use.

[0032] In addition, when the protective film or protective device remains in the electronic device product, for example, when the electronic component is an acoustic component such as a microphone or speaker, it is preferable that the protective film has sound permeability. Even if it is removed after manufacturing, acoustic inspection may be performed during the manufacturing process with the protective film still attached, and in such cases, it is preferable that the protective film has sound permeability.

[0033] In one embodiment, the protective film or device is preferably used to protect the electronic components at least during the solder reflow process.

[0034] More specifically, for example, to secure a package component having a cavity for accommodating an electronic component to another component, soldering may be performed by melting pre-printed solder in a high-temperature furnace. This process is called a solder reflow process. To protect the electronic component from dust and heat, the opening of the package component may be sealed with, for example, a protective film or protective device. By performing the solder reflow process in this state, the electronic component inside the package component can be protected from the dust and heat of the solder reflow process. Furthermore, during the solder reflow process, the air inside the package component tends to expand when placed in a high-temperature furnace. The breathable protective film can suppress excessive pressure expansion and allow heat to escape.

[0035] When the protective film or protective device is used to protect the electronic components at least in the solder reflow process, the protective film or protective device may be attached in a step prior to the solder reflow process to protect the electronic components, or the protective film or protective device may remain in place in a step after the solder reflow process, or even in the product stage of the electronic device after manufacture, to protect the electronic components.

[0036] The electronic devices are not particularly limited, and examples thereof include mobile phones, smartphones, cordless phones, portable music players, portable media players, portable game devices, digital cameras, digital video cameras, headphones, and earphones.

[0037] The electronic components are not particularly limited, and examples thereof include microphones, speakers, semiconductor electronic elements, driver units, and connectors. [Example]

[0038] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0039] The methods for measuring and evaluating each physical property value are as follows. (1) Surface density: Protective film is applied to a 100mm square (area: 0.01m 2 ) and measure the mass with an electronic balance. 2 The mass per unit area was calculated as the areal density.

[0040] (2) Thickness: Using the "SM1201" thickness meter manufactured by Teclock Corporation, which complies with JIS B7503:2017, measurements were taken at 10 random locations and the average value was calculated.

[0041] (3) Average fiber diameter: An image of the protective film was taken at 3000x magnification using an electron microscope, and the diameter of the fibers was measured at 10 random points, and the average value was calculated.

[0042] (4) Average pore diameter: Using an automatic mercury porosimeter "AutoPoreV9600" manufactured by Micromeritics, the average pore diameter of the protective film was measured by setting the pressure measurement range (Report Range) to 0.1 to 61,000 psia (0.0007 to 421 MPa).

[0043] (5) Tensile strength and tensile elongation: In accordance with the method specified in JIS L1096:2010, Method A, test pieces 2.5 cm wide and 20 cm long were cut and tested three times in each of the longitudinal and transverse directions using a tensile tester with a gripping distance of 10 cm and a pulling speed of 15 cm / min. The strength and elongation at break were measured and the average values ​​were calculated.

[0044] (6) Air permeability: The air permeability of the protective film was measured using a "Fragile Permeameter P2" manufactured by Toyo Seiki Seisakusho Co., Ltd. (in accordance with JIS L1096:2010, ISO9237, and ASTMD737).

[0045] (7) Dustproofness: Using the Particle Counter KC-01E manufactured by Rion Co., Ltd., the blocking rate of nano- to micron-order particles (particle diameter 0.3 to 1.0 μm, particle diameter 1.0 to 5.0 μm) was measured (in accordance with JIS B9921:2010).

[0046] (8) Heat resistance: The protective film was heat-treated using a "Desktop Reflow Oven SVO-1" manufactured by Synapex Co., Ltd., with a heating profile (peak temperature 260°C, 10 seconds heat treatment) in accordance with the IPC / J-STD-020D standard. The dimensional shrinkage (%) of the protective film before and after heating was measured.

[0047] (9) Drip resistance: Approximately 1 mL of DYMAX's UV-curable adhesive resin "SPEEDMASK" was dropped onto the surface of the protective film, and immediately after dropping, it was irradiated with UV light to cure, and the degree of penetration of the cured resin was evaluated visually. If no penetration was observed on the back side of the protective film, the drip resistance was deemed good and given an "A," and if penetration was observed, the drip resistance was deemed poor and given a "B."

[0048] (10) Sound Permeability: The sound permeability test will be described with reference to Figure 3. An acrylic housing 16 measuring 70 mm in length, 50 mm in width, and 30 mm in height was prepared and an opening with a diameter of 2 mm was created in this housing 16. Next, sound-absorbing material 14 was filled inside housing 16, and speaker 12 (Star Micronics Co., Ltd.: small speaker SCG-16) was placed inside sound-absorbing material 14 within housing 16 at a distance of 10 ± 1 mm from the opening of the housing. Sound-absorbing material 14 was provided with sound-passing hole 15 with a diameter of 2 mm for the purpose of sound transmission, connecting speaker 12 to the opening of the housing. Furthermore, protective film 11 was punched out to a diameter of 5 mm and attached to the outer surface of housing 16 using double-sided tape in the shape of a ring with an outer diameter of 5 mm and an inner diameter of 3.5 mm, so as to cover the opening of the housing. Thereafter, a microphone 13 (BK4193+BK2633 manufactured by BK) connected to an acoustic evaluation device (PULSE analyzer Type 3110-C manufactured by BK) was placed at a position 10±1 mm away from the protective film 11 that covered the opening of the housing. A chirp wave sound with a frequency of 1 kHz was emitted from the speaker 12, and the sound pressure was measured by the microphone 13. The sound pressure when the protective film 11 was not installed was adjusted to 80 dB, and the difference in sound pressure when the protective film 11 was not installed and when the protective film 11 was installed was calculated as the acoustic loss. An acoustic loss of less than 5 dB at 1 kHz was deemed to have good sound permeability and was given a letter "A," and an acoustic loss of 5 dB or more was deemed to have poor sound permeability and was given a letter "B."

[0049] [Example 1] The non-fluorine-containing polyarylate resin used was Unitika Ltd.'s "Unifiner M-2000H" (glass transition point 275°C, solution viscosity 0.64 dL / g, yellowing index YI 1.2, haze value 0.1%). A 20% by mass spinning solution was prepared consisting of 20 parts by mass of polyarylate resin and 80 parts by mass of cyclohexanone as a solvent. The viscosity of the spinning solution measured using a Brookfield viscometer was 5000 mPa·s (23°C).

[0050] Using the obtained spinning solution, a nanofiber nonwoven fabric of polyarylate resin was obtained by needle-type electrospinning. Specifically, a drum-shaped rotating collector with a diameter of 150 mm was used as a collecting unit, and a release paper sheet (area density 80 g / m) was attached as a substrate to the surface of the rotating collector. 2 A 60 μm thick nanofiber nonwoven fabric was attached to the substrate. Next, a needle with an inner diameter of 0.8 mm was attached horizontally to the rotational direction of the rotating collector, and the spinning solution was supplied to the needle tip at 1.0 mL / h. A voltage of 12 kV was applied to the needle to perform electrospinning. The distance between the needle tip and the grounded rotating collector was 200 mm. The drum-shaped rotating collector was rotated at a speed of 50 rpm, and the needle was 200 mm wide and traversed perpendicular to the rotational direction at a speed of 50 mm / s. Spinning was performed for 120 minutes, resulting in a nanofiber nonwoven fabric layered on the substrate, and a protective film made of the nanofiber nonwoven fabric was obtained.

[0051] The obtained protective film did not fluff even when rubbed on the surface, and was extremely excellent in abrasion resistance, processability, and flexibility. 2 The thickness was 50 μm, the average fiber diameter of the nanofibers was 800 nm, and the average pore diameter was 130 nm. The tensile strength of the protective film was 1.9 N / mm 2 The tensile elongation was 16%. The air permeability of the protective film was 32 cm 3 / (cm 2The dustproofness of the protective film was 99% for a thickness of 0.3 to 1.0 μm, and 99% for a thickness of 1.0 to 5.0 μm. Regarding heat resistance, the dimensional shrinkage rate before and after heating was within 1%. Regarding drip resistance, there was no penetration of the cured resin to the backside, and the film was rated A. Regarding sound permeability, the acoustic loss at a frequency of 1 kHz was 2 dB, and the film was rated A.

[0052] [Example 2] In the needle-type electrostatic spinning method, the discharge speed from the needle was changed from 1.0 mL / h to 3.6 mL / h, the applied voltage was changed from 12 kV to 20 kV, and the spinning time was changed from 120 minutes to 20 minutes. Otherwise, the protective film of Example 2 was obtained in the same manner as Example 1.

[0053] [Example 3] In the needle-type electrospinning method, the protective film of Example 3 was obtained in the same manner as in Example 1, except that the needle inner diameter was changed from 0.8 mm to 0.4 mm and the needle distance was changed from 200 mm to 160 mm.

[0054] [Example 4] In the needle-type electrospinning method, the extrusion speed from the needle was changed from 1.0 mL / h to 2.0 mL / h, and the spinning time was changed from 120 minutes to 60 minutes. The protective film of Example 4 was obtained in the same manner as in Example 1.

[0055] [Example 5] The concentration of the polyarylate resin in the spinning solution was changed to 22 mass %, and otherwise the protective film of Example 5 was obtained in the same manner as in Example 1. The viscosity of the spinning solution was 10,000 mPa·s (23° C.).

[0056] [Comparative Example 1] The protective film of Comparative Example 1 was obtained in the same manner as in Example 1, except that the concentration of the polyarylate resin in the spinning solution was changed to 22% by mass, the diameter of the drum-shaped rotary collector was changed to 75 mm, the rotation speed of the drum-shaped rotary collector was changed to 10 rpm, the needle width was changed to 100 mm, the speed was changed to 20 mm / s, and the spinning time was changed from 120 minutes to 30 minutes. The viscosity of the spinning solution measured with a B-type viscometer was 10,000 mPa s (23°C).

[0057] Comparative Example 2 A spinning solution with a resin concentration of 20% by mass was prepared using Unitika Ltd.'s polyimide precursor "U Imide Varnish" instead of polyarylate resin and dimethylacetamide (DMAC) as the solvent. Using the resulting spinning solution, a nanofiber nonwoven fabric was obtained by needle electrospinning (needle distance 200 mm, needle traverse speed 50 mm / s, discharge speed 1.0 mL / h, applied voltage 12 kV, drum-shaped rotating collector rotation speed 50 rpm, spinning time 120 minutes) similar to that of Example 1. This was followed by a thermal curing treatment for 2 hours in a 400°C chamber to obtain a protective film of Comparative Example 2 consisting of a polyimide resin nanofiber nonwoven fabric.

[0058] Comparative Example 3 A porous PTFE stretched film manufactured by Chukoh Chemical Industries, Ltd. was used as the protective film of Comparative Example 3.

[0059] The protective films of Examples 2 to 5 and Comparative Examples 1 to 3 were measured or evaluated for areal density, thickness, average fiber diameter, average pore diameter, tensile strength, tensile elongation, air permeability, dust resistance, heat resistance, drip resistance, and sound permeability. The results are shown in Table 1 below, along with the results of Example 1. In Table 1, "PAR" stands for polyarylate, and "PI" stands for polyimide.

[0060] [Table 1]

[0061] As shown in Table 1, the protective films of Examples 1 to 5, which were made of polyarylate resin nanofiber nonwoven fabric, were excellent in heat resistance, and as a nanofiber nonwoven fabric, were excellent in breathability and dust resistance, satisfying the performance required of a protective film for electronic components. In particular, the protective films of Examples 1 to 4 were superior in dust resistance to the protective film of Example 5.

[0062] On the other hand, the protective film of Comparative Example 2 made of polyimide nonwoven fabric and the protective film of Comparative Example 3 made of porous PTFE membrane satisfied the performance required for protective films for electronic components, but the manufacturing process was complicated and required a heat curing treatment after film formation, resulting in high costs. In contrast, the protective films of Examples 1 to 5 did not require a complicated manufacturing process, allowed the production of nanofiber nonwoven fabric at a relatively low cost, and did not require energy for a heat curing treatment after film formation, which was cost-effective. Moreover, they were made of environmentally friendly non-fluorine-containing materials.

[0063] The protective films of Examples 1 to 5 were also excellent in mechanical properties, and in terms of sound permeability, they had acoustic properties comparable to those of the polyimide nonwoven fabric of Comparative Example 2 and the porous PTFE film of Comparative Example 3. The protective films of Examples 1 to 3 were also excellent in drip-proof properties.

[0064] In contrast, the protective film of Comparative Example 1, which was made of a nonwoven fabric with an average fiber diameter of more than 3000 nm, had excellent heat resistance but was inferior in dust resistance to Examples 1 to 5. The protective film of Comparative Example 1 also had lower tensile strength and inferior mechanical properties compared to the protective films of Examples 1 to 5.

[0065] The various numerical ranges described in this specification can be arbitrarily combined with their upper and lower limits, and all such combinations are considered to be preferred numerical ranges described in this specification. Furthermore, a numerical range described as "X to Y" means from X to Y. [Explanation of symbols]

[0066] 1...protective device, 2...protective film, 3...heat-resistant double-sided adhesive sheet, 4...protective film area

Claims

1. A protective film for electronic components, comprising a nonwoven fabric of nanofibers of polyarylate resin having an average fiber diameter of 10 to 3000 nm.

2. 2. The protective film for electronic components according to claim 1, wherein the nonwoven fabric has an average pore size of 1 to 500 nm.

3. The mass per unit area of ​​the nonwoven fabric is 0.1 to 20 g / m ２ The protective film for electronic components according to claim 1, wherein

4. 2. The protective film for electronic components according to claim 1, wherein the polyarylate resin has a glass transition temperature of 230 to 300°C.

5. The protective film for electronic components according to claim 1 , wherein the nonwoven fabric is an electrospun nonwoven fabric.

6. 2. The protective film for electronic components according to claim 1, which is used to protect electronic components at least during a solder reflow process.

7. 7. A protective device for electronic components, comprising: the protective film for electronic components according to claim 1; and a heat-resistant double-sided pressure-sensitive adhesive sheet disposed in a peripheral region on at least one main surface of the protective film.

Images