Protective film with low film tearing voltage for protecting electronic component

Abstract

The invention belongs to the field of protective films, and relates to a low-film-tearing-voltage protective film for electronic component protection, the protective film is obtained by coating with a coating liquid, and the coating liquid comprises the following substances by weight: 5-15 parts of beta-wollastonite-based microcrystalline spheres; the invention relates to a high-temperature-resistant coating which comprises the following components in parts by weight: 45-65 parts of composite resin, 1-5 parts of a dispersing agent, 5-10 parts of a functional aid, 2-4 parts of a tackifier and 20-35 parts of a solvent. The film tearing voltage can be reduced, the surface roughness is controlled, and the comprehensive performance is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of protective films, and relates to a protective film with low film tearing voltage for electronic component protection. BACKGROUND

[0002] At present, with the rapid development of electronic information industry, PET protective film as a key material for surface protection of electronic components is widely used in the production of semiconductors, display screens, integrated circuits and the like. However, when the PET protective film is peeled off from the surface of the electronic component, static charges are easily generated due to friction and the like, and the voltage peak value of the static charges can be as high as several thousand volts or even tens of thousands of volts. Such high static voltage can cause a series of serious problems, such as directly breaking the insulating layer of the electronic component, causing short circuit of the component; interfering with the transmission of weak electric signals inside the electronic component, causing data loss or abnormal function of the component; in extreme cases, the instantaneous high temperature generated by static discharge can also burn the precision electronic device, seriously affecting the yield and reliability of the electronic component.

[0003] At present, the existing technology mainly reduces the film tearing static electricity by adjusting the protective film base formula, performing surface antistatic coating treatment and the like. However, these methods have many limitations, for example, changing the base formula can affect the mechanical properties and weather resistance of the protective film; the antistatic effect of simple surface treatment decays quickly and has poor persistence, and it is difficult to fundamentally eliminate the root cause of static generation. In addition, in the coating process of the PET protective film, when functional fillers such as conductive particles are added to the coating liquid, due to the high surface energy of the particles and the easy agglomeration between the particles, the dispersibility of the particles in the coating liquid is poor, thereby causing uneven thickness and rough surface of the coated film layer, greatly affecting the protective performance and appearance quality of the protective film. At the same time, the solidification of the existing coating liquid changes the microstructure of the protective film, and the surface water drop angle is usually between 60°-90°, so that the ion mobility of the film surface is high, the charge accumulates faster when the film is peeled off, high film tearing voltage is generated, and the electronic component is damaged. Therefore, developing a new type of coating liquid which can effectively reduce the film tearing voltage and ensure uniform coating has become a technical problem to be solved in the field of electronic component protection. SUMMARY

[0004] The application provides a protective film with low film tearing voltage for electronic component protection, which can reduce the film tearing voltage, control the surface roughness and improve the comprehensive performance.

[0005] To achieve the above technical purposes, the technical solution adopted by the application is a protective film with low film tearing voltage for electronic component protection, which is obtained by coating a coating liquid, and the coating liquid comprises the following substances in a certain weight ratio:

[0006] As the improved technical solution of the present application, the dispersant is polyoxyethylene sorbitan fatty acid ester.

[0007] As the improved technical solution of the present application, the functional auxiliary agent is composed of 3-5 parts by weight of polyvinyl alcohol and 2-5 parts by weight of polyvinylpyrrolidone.

[0008] As the improved technical solution of the present application, the tackifier is glycerol abietate.

[0009] As the improved technical solution of the present application, the solvent is a mixed solvent composed of ethyl acetate and butanone in a weight ratio of 1:1-3:1.

[0010] As the improved technical solution of the present application, the coating liquid is prepared by the following steps: Step one, preparation of β-wollastonite-based microcrystalline balls; Step two, resin pre-dissolution stage: add acrylic resin and polyurethane resin to the solvent according to the proportion, stir at a speed of 300-500 revolutions per minute for 1-2 hours to form a uniform transparent resin solution; Step three, slowly add β-wollastonite-based microcrystalline balls to the resin solution, keep the stirring speed unchanged, and continue to stir for 0.5-1 hour to make the microcrystalline balls preliminarily dispersed in the resin solution; Step four, add the proportioned dispersant, increase the stirring speed to 600-800 revolutions per minute, and stir for 1-1.5 hours to achieve micron-level uniform dispersion of the microcrystalline balls in the resin system; Step five, proportioned functional auxiliary agent and tackifier, stir at a speed of 400-600 revolutions per minute for 0.5-1 hour to make the components fully integrated, and prepare a low-tear-film-voltage coating liquid.

[0011] Advantages

[0012] The crosslinked chains of acrylic resin (Rohm & Haas B-66) and polyurethane resin (Cognis Desmodur N3300) form hydrogen bonds with the ester groups of glycerol abietate and the hydroxyl groups of the resin, and a three-dimensional network structure formed by interpenetration can improve the weather resistance and adhesion of the film layer, and endow the film layer with higher cohesion and toughness.

[0013] PVA and PVP enhance the dispersion stability of the microcrystalline balls by forming hydrogen bonds with the hydroxyl groups on the surface of the microcrystalline balls, effectively solving the dispersion problem of functional substances and ensuring the uniformity of the film layer thickness.

[0014] As an intelligent tackifier, rosin glyceride forms an interpenetrating network structure with the composite resin, which improves the adhesion without affecting the static control and surface roughness control. It can ensure that the protective film is firmly attached to the surface of the electronic component within the temperature range of-20℃-80℃, and there is no residue when the film is torn, and it does not affect the control of the tearing voltage, ensuring the performance of the protective film.

[0015] The mixed solvent composed of ethyl acetate and butanone has a better evaporation rate, which can ensure uniform drying and curing of the coating liquid during coating process, thereby improving the film quality and production efficiency.

[0016] In summary, the ternary synergistic formulation system of "composite resin-functional microcrystal ball-synergistic additive" is constructed, which realizes the simultaneous optimization and breakthrough of multiple performances of the coating liquid for electronic component protection, and breaks the traditional coating liquid "antistatic performance, dispersion stability, weather resistance, adhesion performance mutual restriction" technical bottleneck. The prepared PET protective film can meet the needs of low tearing voltage, high uniformity, excellent weather resistance and reliable protection performance at the same time, significantly improving the yield and reliability of electronic components, and is widely used in the protection of precision electronic components such as semiconductors and OLED display screens. DETAILED DESCRIPTION

[0017] The "parts" described herein are all weight parts.

[0018] The low tearing voltage protective film for electronic component protection is obtained by coating the coating liquid, and the coating liquid includes the following substances by weight: Beta-wollastonite-based microcrystal ball 5-15 parts Composite resin: 45-65 parts Dispersing agent: 1-5 parts Functional additive: 5-10 parts Tackifier: 2-4 parts Solvent: 20-35 parts.

[0019]

[0020] Composite resin: 45-65 parts, composed of 35-50 parts of acrylic resin and 10-15 parts of polyurethane resin. The acrylic resin is a thermoplastic acrylic resin (such as Rohm & Haas B-66, solid content 50±2%, molecular weight 90000-110000, glass transition temperature Tg=23℃), the monomer units are methyl methacrylate (MMA) and butyl acrylate (BA), the molar ratio MMA:BA=75:25. The polyurethane resin is an aliphatic polyisocyanate (such as Covestro Desmodur N3300, isocyanate group content 21.8%, viscosity 2500 mPa・s), which is polymerized from hexamethylene diisocyanate (HDI) and polybutylene adipate (PBA).

[0021] Dispersant: 1-5 parts of polyoxyethylene sorbitan fatty acid ester (such as Tween 80, HLB value 15.0, polyoxyethylene chain segment EO unit number 20, oleic acid chain C18:1).

[0022] Functional aid: 5-10 parts, composed of 3-5 parts of polyvinyl alcohol and 2-5 parts of polyvinylpyrrolidone. The polyvinyl alcohol (PVA) is a polyvinyl acetate hydrolysis product, the polymerization degree is 500-2000, the alcoholysis degree is ≥98%; the polyvinylpyrrolidone (PVP) is polymerized from N-vinylpyrrolidone, the K value is 30-90.

[0023] Tackifier: 2-4 parts of rosin glycerol ester (acid value ≤10 mgKOH / g, softening point 80-90℃, esterified from abietic acid and glycerol).

[0024] Solvent: 20-35 parts of mixed solvent composed of ethyl acetate and butanone in a weight ratio of 1:1-3:1.

[0025] The preparation process includes the following steps:

[0028]

[0029] Step two, resin pre-dissolution stage: acrylic resin (Rohm & Haas B-66) and polyurethane resin (Covestro Desmodur N3300) are added to the mixed solvent, stirred at a speed of 300-500 revolutions per minute for 1-2 hours to form a uniform transparent resin solution.

[0030] Step three, initial dispersion of microcrystalline spheres: slowly add β-wollastonite-based microcrystalline spheres (Na⁺doped), keep the stirring speed unchanged, continue to stir for 0.5-1 hour, so that the β-wollastonite-based microcrystalline spheres are initially dispersed in the resin solution.

[0031] Step four, depth dispersion reinforcement: add the proportioning amount of dispersant, increase the stirring speed to 600 - 800 rpm, and stir for 1-1.5 hours to achieve micron-level uniform dispersion of the microcrystal balls in the resin system.

[0032] Step five, functional component fusion: add the proportioning amount of functional additives and tackifiers in sequence, stir at a speed of 400 - 600 rpm for 0.5-1 hour to make the components fully fuse, and prepare the low-tear-film voltage coating liquid.

[0033] Example 1

[0034] 3. Film forming process: uniformly coat the prepared coating liquid on the surface of the PET substrate, dry at 80℃ for 15 minutes, and then cure at 120℃ for 30 minutes to prepare the PET protective film.

[0035] 4. Performance test results: see Table 1.

[0036] Example 2

[0037] 2. Preparation process: complete the steps of resin pre-dissolution, dispersion of β-wollastonite-based microcrystal balls (referred to as microcrystal balls), and functional component fusion in sequence according to the preparation process of Example 1 to prepare the coating liquid.

[0038] 3. Film forming process: coat the coating liquid on the PET substrate and perform curing treatment to prepare the PET protective film.

[0039] 4. Performance test results: see Table 1.

[0040] Example 3

[0041] 2. Preparation process: complete the steps of resin pre-dissolution, dispersion of microcrystal balls, and functional component fusion in sequence according to the preparation process of Example 1 to prepare the coating liquid.

[0042] 3. Film forming process: coat the coating liquid on the PET substrate and perform curing treatment to prepare the PET protective film.

[0043] 4. Performance test results: see Table 1.

[0044] Example 4

[0045] 2. Preparation process: complete the steps of resin pre-dissolution, dispersion of microcrystal balls, and functional component fusion in sequence according to the preparation process of Example 1 to prepare the coating liquid.

[0046] 3. Film forming process: The coating liquid is coated on the PET substrate and cured to obtain the PET protective film.

[0047] 4. Performance test results: see Table 1.

[0048] Example 5

[0049] 2. Preparation process: The coating liquid is prepared by sequentially completing the steps of resin pre-dissolution, microcrystal ball dispersion, and functional component fusion according to the preparation process of Example 1.

[0050] 3. Film forming process: The coating liquid is coated on the PET substrate and cured to obtain the PET protective film.

[0051] 4. Performance test results: see Table 1.

[0052] Comparative Example 1 (without adding β-wollastonite-based microcrystal balls) 1. Raw material preparation: The acrylic resin (Rohm & Haas B-66) 45 parts, polyurethane resin (Cognis Desmodur N3300) 12 parts, Tween 80 3 parts, PVA 4 parts, PVP 3 parts, rosin glyceride 3 parts, ethyl acetate 15 parts, and butanone 15 parts are weighed according to the weight fraction.

[0053] 2. Preparation process: The coating liquid is prepared by sequentially completing the steps of resin pre-dissolution and functional component fusion according to the preparation process of Example 1.

[0054] 3. Film forming process: The coating liquid is coated on the PET substrate and cured to obtain the PET protective film.

[0055] 4. Performance test results: see Table 1.

[0056] Comparative Example 2 (without adding PVA and PVP)

[0057] 2. Preparation process: The coating liquid is prepared by sequentially completing the steps of resin pre-dissolution and microcrystal ball dispersion according to the preparation process of Example 1.

[0058] 3. Film forming process: The coating liquid is coated on the PET substrate and cured to obtain the PET protective film.

[0059] 4. Performance test results: see Table 1.

[0060] Comparative Example 3 (traditional coating liquid formula) 1. Raw material preparation: A commercially available ordinary PET protective film coating liquid formula was used, acrylic resin (Rohm & Haas B-66) 50 parts, antistatic agent (conventional quaternary ammonium salt) 3 parts, plasticizer 2 parts, solvent (ethyl acetate) 45 parts.

[0061] 2. Preparation process: According to the preparation process of Example 1, the steps of resin pre-dissolution, functional component fusion, etc. were sequentially completed to prepare the coating liquid.

[0062] 3. Film forming process: The coating liquid was coated on the PET substrate and cured to obtain the PET protective film.

[0063] 4. Performance test results: see Table 1.

[0064] Performance test method and corresponding national standard: 1. Film tearing voltage: According to GB / T 36396-2018 "General Specification for Thin Film Antistatic Materials for Electronic and Electrical Products", using an electrostatic voltage tester, the PET protective film was tightly attached to the adherend, and the electrostatic voltage generated at the moment of film tearing was measured at a speed of (300±10) mm / min.

[0065] 2. Water drop angle: According to GB / T 30693-2014 "Measurement of Water Contact Angle of Plastic Film", using a contact angle measuring instrument, under the conditions of room temperature (23±2) ℃ and relative humidity (50±5) %, a deionized water drop was placed on the surface of the PET protective film at a rate of 0.1 μL / s, and the angle between the water drop and the film surface was measured after stabilization.

[0066] 3. Surface resistivity: According to GB / T 1410-2006 "Test Method for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", using a high resistance meter, the sample size was 100 mm x 100 mm, and the test voltage was 100 V.

[0067] 4. Peel strength: According to GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tape", a 25 mm wide PET protective film was attached to a standard steel plate, and an electronic universal material testing machine was used to perform a 180° peel test at a speed of (300±10) mm / min to measure the adhesion value.

[0068] 5. Weather resistance: After the PET protective film was attached to the glass, it was placed in a constant temperature and humidity chamber with a temperature of 85℃ and a relative humidity of 85%, and a weather resistance test was conducted for 500h. After the test, the protective film on the glass surface was observed for the presence of edge lifting, slits, and bubbles. If none were present, it was considered acceptable, and if any were present, it was considered unacceptable.

[0069]

[0070] The target PET protective film of the present application is to solve the pain points of the prior art "high film tearing voltage, poor antistatic stability, insufficient weather resistance, and unbalanced film layer performance", and ultimately to meet the comprehensive requirements of "low static damage, high protection reliability, and adaptation to precise electronic component use scenarios". Therefore, it has the following performance requirements: (1) Film tearing voltage: ≤80V, preferably ≤50V; Film tearing voltage is a core indicator for protecting precise electronic components (such as OLED display screens and semiconductor chips). As shown in Table 1, the film tearing voltage of Examples 1-5 of the present application is 40-80V (Example 3 is as low as 40V), which is much lower than the comparative examples (800-2500V for Comparative Examples 1-3), and the target needs to be controlled within 80V — this range can avoid static breakdown of electronic component insulating layers, interference with weak electrical signals, or burning of precise devices, ensuring improved electronic component yield.

[0071]

[0072] (3) High water drop angle can slow down the charge accumulation speed during the protective film tearing process, while improving the film layer's anti-fouling property (reducing dust and water vapor adhesion), indirectly ensuring the stability of the antistatic performance.

[0073] (4) Peel force needs to balance "stable adhesion" and "film tearing without residue", and the test value of the examples is 1.02-2.21 gf / 25mm (2.27-2.45 gf / 25mm for the comparative examples), which is targeted to be within this range. It ensures that the protective film is stably adhered to the surface of the electronic component (without falling off) within the temperature range of -20°C-80°C, and can be easily peeled off after use without residue to contaminate the surface of the electronic component.

[0074] (5) Surface roughness directly affects the appearance and protection precision of the film layer, and the test value of the examples is 0.65-0.95 nm (0.48-0.53 nm for the comparative examples), and the target needs to be ≤1.0 nm. This indicator can ensure that the film layer is smooth and flat, avoiding surface scratches caused by particle agglomeration that can scratch electronic components (such as OLED display screen glass substrates). Although the test value of the examples increases slightly due to the addition of target substances, it meets the device use requirements (≤1.0 nm), and at the same time makes the protective film stand out with low film tearing voltage characteristics.

[0075] (6) Weather resistance is the key to long-term use of protective films, and the examples all pass this test (no edge lifting, slits, or bubbles), while the comparative examples are all unqualified. The target needs to meet this weathering requirement — it can adapt to high temperature and high humidity environments during the production, storage, and transportation of electronic components, avoid film layer aging failure, and ensure consistent and stable protection performance.

Claims

1. A protective film for electronic components, which is a low- tear film voltage protective film, characterized by comprising: Coating liquid is obtained by coating, the coating liquid comprises the following substances in parts by weight:

2. The low peel film voltage protective film for electronic components according to claim 1, characterized by The dispersant is polyoxyethylene sorbitan fatty acid ester.

3. The low peel film voltage protective film for electronic component protection according to claim 1, characterized by, The functional aid is composed of 3-5 parts by weight of polyvinyl alcohol and 2-5 parts by weight of polyvinylpyrrolidone.

4. The low voltage protective film for electronic component protection according to claim 1, wherein The tackifier is glycerol ester of wood rosin.

5. The low voltage protective film for electronic component protection according to claim 1, wherein The solvent is a mixed solvent composed of ethyl acetate and butanone in a weight ratio of 1:1-3:

1.

6. The low voltage protective film for electronic component protection according to claim 1, wherein The coating liquid is prepared by the following steps: Step one, preparation of β-wollastonite-based microcrystalline ball; Step two, resin pre-dissolution stage: add acrylic resin and polyurethane resin into solvent according to the proportion, stir at a speed of 300-500 rpm for 1-2 hours to form a uniform transparent resin solution; Step three, slowly add β-wollastonite-based microcrystalline ball into the resin solution, keep the stirring speed unchanged, continue to stir for 0.5-1 hour, so that the β-wollastonite-based microcrystalline ball is preliminarily dispersed in the resin solution; Step four, add the proportioned dispersant, increase the stirring speed to 600-800 rpm, stir for 1-1.5 hours to achieve micron-level uniform dispersion of β-wollastonite-based microcrystalline ball in the resin system; Step five, add the proportioned functional aid and tackifier, stir at a speed of 400-600 rpm for 0.5-1 hour to make the components fully integrated, and obtain a low-tear-film-voltage coating liquid.

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