LED light excitation curing resin composition and electronic device

Abstract

The invention provides an LED light excitation curing resin composition and an electronic device, the resin composition comprises the following components by mass: 0.1%-2% of a sulfonium salt cationic first photoinitiator, 0.1%-2% of a second photoinitiator, 0.5%-5% of a thermal acid generator, 20%-60% of matrix resin, 2%-10% of functional resin, 0%-5% of a silane coupling agent, and 20%-80% of a filler and an auxiliary agent. Under the condition of local shading, the curable depth of the shading part of the adhesive layer formed by the resin composition is greater than or equal to 2mm when the adhesive layer is excited by an LED light source with the wavelength of 395nm-450nm, and the curable depth of the exposed part of the adhesive layer is greater than or equal to 5mm. The resin composition provided by the invention can effectively improve the curing efficiency of the resin composition in a shading area and improve the curable depth of the resin composition. When the resin composition is used as a glue solution for mounting the shading element in the electronic device, the mechanical reliability of the electronic device can be improved, the bonding strength of the shading element in the electronic device is enhanced, and the normal use of the electronic device is guaranteed.

Description

Technical Field

[0001] This application relates to the field of resin technology, and more specifically, to resin compositions and electronic devices that are cured by LED light excitation. Background Technology

[0002] Photopolymerization technology is the process of polymerizing liquid photosensitive resins into solids under light induction. It is characterized by high efficiency, speed, economy, energy saving, and environmental friendliness, and is widely used in adhesives, photocurable coatings and inks, photoresists, 3D microstructures, and biomedicine. The photocurable monomer is a key factor controlling the overall performance of the cured product; its activity and dilution properties directly affect the curing rate, degree of curing, and end-product performance. Especially in applications such as coatings, free radical curing is typically carried out in an air atmosphere. Therefore, oxygen in the air diffuses into the polymerization system and reacts with free radicals generated under light irradiation by the photoinitiator, thus inhibiting photopolymerization. This is one of the biggest challenges in the field of photopolymerization: oxygen inhibition. Cationic photocurable systems are not sensitive to oxygen. Their polymerizable monomers are mainly epoxides, and the polymerization mechanism is mainly ring-opening polymerization, resulting in lower shrinkage of the cured product. Therefore, cationic photocurable systems have seen rapid development in recent years in fields such as optical adhesives and photocurable adhesives. In particular, electronic adhesives, which are highly sensitive to volume shrinkage, are a key research topic in industry, academia, and research.

[0003] In the assembly of electronic components using cationic photocurable resin compositions, the adhesive and the bonded object are often rigid, resulting in gaps during bonding. During dispensing and before photocuring, the liquid adhesive flows into these gaps. If either the adhesive or the bonded object has an opaque light-blocking element, the adhesive in the light-blocking area will not receive sufficient light and will be difficult to cure effectively, affecting the performance of the electronic components. Improving the curing efficiency of the adhesive in the light-blocking area and increasing the curing depth is currently a challenge in the industry. Summary of the Invention

[0004] This application proposes an LED photocurable resin composition and electronic device, which can effectively improve the curing efficiency of the resin composition in the light-shielding area and increase the curable depth of the resin composition. When the resin composition is used as an adhesive for mounting light-shielding elements in electronic devices, it can improve the mechanical reliability of the electronic devices, enhance the bonding strength of the light-shielding elements in the electronic devices, and ensure the normal use of the electronic devices.

[0005] In a first aspect, this application provides a resin composition for LED photoexcitation and curing, wherein, by weight percentage, the resin composition comprises:

[0006] The composition includes: 0.1%–2% of a thioonium salt cationic primary photoinitiator, 0.1%–2% of a secondary photoinitiator, 0.5%–5% of a thermogenic acid generator, 20%–60% of a main resin, 2%–10% of a functional resin, 0%–5% of a silane coupling agent, and 20%–80% of fillers and additives.

[0007] Under partial light-shielding conditions, when the adhesive layer formed by the resin composition is excited by an LED light source with a wavelength of 395nm to 450nm, the curable depth of the light-shielded portion of the adhesive layer is ≥2mm, and the curable depth of the exposed portion of the adhesive layer is ≥5mm.

[0008] In some embodiments, the structural formula of the thionium salt-based cationic first photoinitiator is shown in Formula I:

[0009]

[0010] In equation I, X1 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them.

[0011] In some embodiments, the second photoinitiator is selected from at least one of the compounds shown in Formula II-1 and Formula II-2:

[0012]

[0013] In equations II-1 and II-2, X2 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them.

[0014] In some embodiments, the thermal acid-generating agent is selected from at least one of the compounds shown in Formula III-1, Formula III-2, and Formula III-3:

[0015]

[0016] In equations III-1, III-2, and III-3, X3 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4— (CF3SO2)2N — One of them.

[0017] In some embodiments, the host resin is an alicyclic epoxy resin.

[0018] In some embodiments, the alicyclic epoxy resin is selected from compounds with the following structures:

[0019]

[0020] In some embodiments, the resin composition further includes a dilutive monomer in a mass ratio of 0 to 30%, based on 100% by weight of the resin composition.

[0021] Specifically, the dilutive monomer is selected from at least one compound with the following structural formulas:

[0022]

[0023] In some embodiments, the silane coupling agent may be selected from at least one compound with the following structural formulas:

[0024]

[0025] In some embodiments, the functional resin includes at least one selected from polymeric epoxy resin, epoxidized polybutadiene, and polyester polyol. In other embodiments, the functional resin may also be an oxetane compound.

[0026] In some embodiments, the filler is selected from at least one of silica and alumina, and the particle size of the filler is less than or equal to 20 μm.

[0027] In some embodiments, the resin composition comprises 50% to 80% by weight of nano-silica particles.

[0028] In some embodiments, based on the mass of the resin composition, the additives include at least one of the following: a rheology accelerator at a mass percentage of 0-2%, a leveling agent at a mass percentage of 0-0.5%, and a defoamer at a mass percentage of 0-0.5%.

[0029] In some embodiments, the illuminance of the LED light source that excites the curing of the resin composition is 10 mW / cm². 2 ~1000mW / cm 2 .

[0030] Secondly, this application provides an electronic device, including a substrate and a light-shielding element mounted on the substrate. An adhesive layer is provided between the light-shielding element and the substrate. The adhesive layer is made of the aforementioned resin composition. The adhesive layer includes an exposure portion and a light-shielding portion. The light-shielding portion is used to connect the substrate and the light-shielding element. The light-shielding portion is obtained by curing the resin composition after excitation by an LED light source with a wavelength of 395nm to 450nm. The exposure portion is obtained by curing the resin composition after excitation by an ultraviolet light source with a wavelength of 360nm to 370nm.

[0031] In some embodiments, the thickness of the exposed portion is H1, and the thickness of the light-shielding portion is H2, where H2 ≤ H1.

[0032] In some embodiments, the distance between the exposed portion and the edge of the light-shielding portion is L1, where 2H2≤L1≤5H2.

[0033] In some embodiments, the bonding strength between the light-shielding element and the substrate is ≥10 MPa.

[0034] In some embodiments, the exposure portion surrounds the edge of the light-shielding element and is connected to the substrate.

[0035] Compared with the prior art, this application has at least the following technical effects:

[0036] The resin composition provided in this application, after being irradiated once by an LED light source (425nm) at room temperature, can initially fix electronic components under the action of a first photoinitiator of thioonium salt type that is sensitive to LED light, due to the addition of a first photoinitiator that is sensitive to LED light. The pre-curing time is only about 10s to 30s. As photolysis proceeds, the first photoinitiator on the surface of the resin composition no longer absorbs photons after photolysis, and the curing rate is slowed down. During this period, the reaction heat generated by the cross-linking polymerization reaction of the main resin continuously accumulates until it reaches the decomposition temperature of the thermal acid-generating agent, so that the assembly operability window time of the electronic components can reach about 2 minutes. At the same time, the by-product obtained from the decomposition of the first photoinitiator acts as a photosensitizer and works with the thermal acid-generating agent, so that even if the electronic components are light-shielding components, the light-shielding area of ​​the adhesive layer covered by the electronic components can be fully cured. Then, a second irradiation is performed using a 365nm light source. The second photoinitiator is sensitive to the 365nm light source, and under irradiation, the resin composition can be fully cured in both the exposed and shaded areas. In particular, the curable depth of the shaded area can reach 2mm to 4mm. This combination of long and short wavelength light sources enables a step-by-step curing process of rapid pre-fixation at room temperature followed by complete curing at room temperature. No additional heating is required during the entire step-by-step curing process, which reduces the damage to electronic components caused by residual thermal stress in the adhesive layer and reduces the deformation of electronic components. It is particularly suitable for the installation of some heat-sensitive components, replacing the traditional heating curing process and ensuring the long-term stability of electronic components. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the assembly of electronic devices provided in the embodiments of this application.

[0038] Figure 2 A schematic diagram of the structure of the electronic device provided in the embodiments of this application.

[0039] Figure 3a This is a schematic diagram showing the cured state of the samples prepared in the embodiments and comparative examples of this application.

[0040] Figure 3b This is a schematic diagram of the cured state of the sample prepared as a comparative example in this application.

[0041] Figure 4 This is a schematic diagram of a method for verifying the curability depth of the resin composition prepared in the embodiments of this application under light-shielding conditions.

[0042] Figure 5 This is a schematic diagram showing the cured state of the samples prepared in the embodiments and comparative examples of this application.

[0043] Figure 6a This is a heat flow curve of the resin composition in an embodiment of this application.

[0044] Figure 6b This is a graph showing the polymerization conversion rate of the resin composition in an embodiment of this application. Detailed Implementation

[0045] The technical solutions provided by the present invention will be further described below with reference to specific embodiments and comparative examples, but this application is not limited to the following embodiments.

[0046] Cationic photocurable systems have seen rapid development in recent years in fields such as optical adhesives and photocurable adhesives. In particular, electronic adhesives, which are highly sensitive to volume shrinkage, have become a key research topic in industry, academia, and research.

[0047] In the assembly of electronic components using cationic photocurable resin compositions, the adhesive and the bonded object are often rigid, resulting in gaps during bonding. During dispensing and before photocuring, the liquid adhesive flows into these gaps. If either the adhesive or the bonded object has an opaque light-blocking component, the adhesive in the light-blocking area will not receive sufficient light and will be difficult to cure effectively, affecting the performance of the electronic components. Improving the curing efficiency of the adhesive in light-blocking areas and increasing the curing depth is currently a challenge in the industry.

[0048] According to the Lambert-Beer Law: A = lg(1 / T) = KLc, where A is absorbance, T is transmittance, which is the ratio of emitted light intensity (I) to incident light intensity (I0); K is the molar absorptivity, which is related to the properties of the absorbing substance and the wavelength λ of the incident light; c is the concentration of the absorbing substance, in mol / L; and L is the thickness of the absorption layer, in cm.

[0049] For a thicker adhesive layer to fully cure, the first method is to ensure sufficient light intensity, but the light intensity (A) cannot be too high. Therefore, with a fixed concentration (c) and thickness (L), this can only be achieved when the molar absorptivity (K) is relatively low. Light absorption is primarily achieved by the photoinitiator; fillers also absorb or scatter light. The initiator absorbs photon energy and decomposes to produce active species, thus achieving photocuring. However, ordinary photoinitiators remain essentially constant before and after light exposure. Therefore, once the adhesive layer thickness increases, the light energy is almost entirely absorbed by the surface layer, preventing effective curing of the deeper layers. Even with increased light intensity, the Beer-Lambert law dictates that light intensity decays exponentially, resulting in poor curing at the bottom of thicker adhesive layers. After dispensing and before photocuring, the liquid adhesive flows into the gaps between the adhesive and the substrate. If these gaps are blocked, the adhesive within them cannot absorb light, further hindering full curing and impacting the performance of electronic devices.

[0050] In some implementations, thermosetting epoxy adhesive is applied to the fixing points of the substrate and electronic components, and then ultraviolet light is used to achieve rapid photocuring for 10-30 seconds. Then, heating and baking are used to completely cure the adhesive layer. This photocuring process is not suitable for situations where the electronic components are light-shielding components. The assembled electronic components are also prone to thermal deformation, or there may be thermal stress between the adhesive layer and the electronic components. During subsequent use, the electronic components are prone to damage or deformation.

[0051] Therefore, this application provides a resin composition for LED photoexcitation curing, wherein the resin composition comprises, by weight percentage:

[0052] The composition includes: 0.1%–2% of a thioonium salt cationic primary photoinitiator, 0.1%–2% of a secondary photoinitiator, 0.5%–5% of a thermogenic acid generator, 20%–60% of a main resin, 2%–10% of a functional resin, 0%–5% of a silane coupling agent, and 20%–80% of fillers and additives.

[0053] Under partial light-shielding conditions, when the adhesive layer formed by the resin composition is excited by an LED light source with a wavelength of 395nm to 450nm, the curable depth of the light-shielded portion of the adhesive layer is ≥2mm, and the curable depth of the exposed portion of the adhesive layer is ≥5mm.

[0054] After the resin composition is irradiated once at room temperature by an LED light source (425nm long-wavelength light), the addition of a first photoinitiator, a thionium salt cationic type sensitive to LED light, allows for initial fixation of electronic components. The pre-curing time is only about 10-30 seconds. As photolysis proceeds, the first photoinitiator on the surface of the resin composition stops absorbing photons after photolysis, photodecomposition is inhibited, and the curing rate is slowed down. During this period, the heat generated by the cross-linking polymerization reaction of the main resin continuously accumulates, reaching the decomposition temperature of the thermogenic acid agent. This allows the operability window for electronic component assembly to reach about 2 minutes. Simultaneously, the byproducts from the decomposition of the first photoinitiator act as photosensitizers, working in conjunction with the thermogenic acid agent to ensure that even if the electronic component is a light-shielding element, the light-shielding area of ​​the adhesive layer covered by the electronic component can be fully cured. Then, a second irradiation is performed using a 365nm light source (short-wavelength light). The second photoinitiator is sensitive to the 365nm light source, and under this light irradiation, both the exposed and light-shielding parts of the resin composition can be fully cured. The combination of long and short wavelength light sources enables a step-by-step curing process that combines rapid pre-fixation at room temperature with complete curing at room temperature. No additional heating is required during the entire step-by-step curing process, which reduces the damage to electronic components caused by residual thermal stress in the adhesive layer and reduces the deformation of electronic components. It is particularly suitable for the installation of some heat-sensitive components, replacing the traditional heating curing process and ensuring the long-term stability of electronic components.

[0055] In some embodiments, the first photoinitiator, a thionium salt cationic type, has a light absorption wavelength in the range of 395 nm to 425 nm, enabling long-wavelength light initiation for LED light sources. Its specific structural formula is shown in Formula I:

[0056]

[0057] In equation I, X1 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them. It should be noted that the embodiments of this application provide anion as SbF6. — The first photoinitiator, other first photoinitiators composed of anions are also sensitive to LED light sources in the wavelength range of 395nm to 425nm.

[0058] The thionium salt-based cationic primary photoinitiator is sensitive to LED light (long-wavelength light) and has a push-pull electron type D-π-A molecular structure. Its electron-withdrawing ability is provided by the thionium salt, which is sensitive to LED light. After photolysis, the molecular structure of the primary photoinitiator molecule becomes a D-π-D structure. The byproducts obtained from the decomposition of the primary photoinitiator have strong fluorescence and can be used as photosensitizers to sensitize the secondary photoinitiator. The photosensitizer has a high fluorescence quantum yield. When excited by an LED light source, the entire resin composition system emits light, which acts as a secondary light source, allowing light to diffuse to the bottom region and the light-shielding region of the adhesive layer. The light can gradually penetrate from the surface of the adhesive layer to the bottom layer, which helps the resin composition achieve deep photocuring. At the same time, the reaction heat generated by the cross-linking polymerization reaction of the resin on the surface of the adhesive layer serves as a heat source for the thermogenic acid, promoting the decomposition of the thermogenic acid to form a catalyst. The catalyst continues to promote the cross-linking polymerization of resin molecules, thereby forming an energy cycle that can achieve photocuring of thicker adhesive layers. Furthermore, the heat of reaction generated by photoinitiated polymerization is used as a heat source for the thermogenic acid agent, thereby promoting the polymerization of the resin composition in the light-shielding region under the synergistic effect of the thermogenic acid agent. In this application, under the synergistic effect of the first photoinitiator, the second photoinitiator, and the thermogenic acid agent, the curing effect of the adhesive layer in the light-exposed region can extend to the curing of the adhesive layer in the light-shielding region, so that the resin composition in the light-shielding region is effectively cured; the resin composition of this application can also achieve photocuring of a relatively thick adhesive layer.

[0059] Specifically, the mass percentage of the first photoinitiator in the resin composition is 0.1% to 2%, specifically 0.1%, 0.2%, 0.3%, 0.5%, 0.7%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, or 2%, etc., and is not limited thereto. Preferably, the mass percentage of the first photoinitiator is 0.4% to 1%. Controlling the amount of the first photoinitiator added in the embodiments of this application within the above range can better catalyze the occurrence of the crosslinking reaction, increase the curable depth or depth of the exposed area, and improve the curing conversion rate.

[0060] In some embodiments, the second photoinitiator is a thionium salt cationic photoinitiator and / or a canonical salt cationic photoinitiator.

[0061] In some specific embodiments, the second photoinitiator may be selected from at least one of the compounds shown in Formula II-1 and Formula II-2:

[0062]

[0063] In equations II-1 and II-2, X2 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them. It should be noted that the embodiments of this application provide anion as SbF6. — The second photoinitiator, and other second photoinitiators composed of anions are also sensitive to ultraviolet light in the wavelength range of 300nm to 365nm.

[0064] The second photoinitiator also has a D-π-A (push-pull electron) structure. After photolysis, the photoinitiator molecule as a whole becomes a D-π-D structure, resulting in a blue shift in the absorption wavelength of the byproducts. Compared with the first photoinitiator, which is a thioonium salt cationic type, the absorbance in the wavelength region above 365 nm decreases. The second photoinitiator is sensitive to ultraviolet light in the range of 300 nm to 365 nm. The combined use with the byproducts of the first photoinitiator (i.e., photosensitizers) can realize the photopolymerization and curing of the resin composition in the range of 365 nm to 425 nm, improve the curing reaction activity, and help improve the degree of curing and achieve complete curing.

[0065] The mass percentage of the second photoinitiator in the resin composition is 0.1% to 2%, specifically 0.1%, 0.2%, 0.3%, 0.5%, 0.7%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, or 2%, etc., and is not limited herein. Preferably, the mass percentage of the second photoinitiator is 0.5% to 2%. Controlling the amount of the second photoinitiator added in the embodiments of this application within the above range can better catalyze the crosslinking reaction and improve the curing efficiency of the exposed area.

[0066] In some embodiments, the mass ratio of the first photoinitiator to the second photoinitiator in the resin composition is 1:(5-15). Controlling this mass ratio within the aforementioned range allows the first photoinitiator to achieve pre-fixation after a single light exposure, while the second photoinitiator enables deep curing after a second light exposure. The combined effect of both achieves deep curing. When the amount of the first photoinitiator is too small, the resin composition cannot achieve pre-fixation under an LED light source in a short time, making it impossible to excite the entire resin composition using an LED light source.

[0067] In some embodiments, the thermal acid-generating agent has a different decomposition temperature, and its use in combination with the byproduct of the first photoinitiator (i.e., photosensitizer) can achieve effective curing of the resin composition in the shaded area after photoactivation.

[0068] Specifically, the thermal acid-generating agent is selected from at least one of the compounds shown in Formula III-1, Formula III-2, and Formula III-3:

[0069]

[0070] In equations III-1, III-2, and III-3, X3 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them. It should be noted that the embodiments of this application provide anion as SbF6. — Thermoacids, other anionic thermoacids can also be thermally decomposed upon heating, and their thermal decomposition byproducts (cationic group portion) are used in combination with the byproducts of the first photoinitiator (i.e., photosensitizers).

[0071] Specifically, the mass percentage of the heat-generating acid agent in the resin composition is 0.5% to 5%, specifically 0.5%, 0.8%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc., and is not limited herein. Preferably, the mass percentage of the heat-generating acid agent in the resin composition is 0.9% to 2%.

[0072] In some embodiments, the host resin may be an epoxy resin monomer and / or an epoxy resin prepolymer, or it may be an oxacyclobutane compound. Preferably, the host resin is an alicyclic epoxy resin.

[0073] The main resin in the resin composition comprises 20% to 60% by mass, specifically 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%, etc., and is not limited herein. Preferably, the main resin in the resin composition comprises 20% to 40% by mass. In practical applications, the amount of main resin added can be adjusted according to the material properties of the main resin, and is not limited herein.

[0074] In some embodiments, the alicyclic epoxy resin is selected from compounds with the following structures:

[0075]

[0076] In some embodiments, the functional resin includes at least one of polymeric epoxy resin, epoxidized polybutadiene, and polyester polyol, and may also be an oxetane compound. In this application, adding a functional resin to the resin composition can improve the toughness of the cured resin system, or enable the resin composition to achieve certain special properties, such as conductivity or low impedance.

[0077] For example, the structural formula of a polymeric epoxy resin can be shown in formula (1) below, where R is an organic group.

[0078]

[0079] Specifically, the functional resin in the resin composition accounts for 2% to 10% by mass, and may be 2%, 3%, 5%, 6%, 8%, 9%, or 10%, etc., without limitation.

[0080] To increase the adhesion and bonding strength of the adhesive layer formed by the resin composition and improve the compatibility of the components in the resin composition, the resin composition also includes a silane coupling agent, with the mass percentage of the silane coupling agent in the resin composition being 0% to 5%. If the resin composition does not require excessive tackiness, such as when used as a component gasket, then the silane coupling agent does not need to be added to the resin composition.

[0081] Specifically, the silane coupling agent includes at least one selected from γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and 3-(2,3-epoxypropoxy)propyltrimethoxysilane. The mass percentage of the silane coupling agent in the resin composition can be 0%, 0.5%, 0.8%, 1.0%, 1.5%, 2%, 2.5%, 3%, 4%, or 5%, etc., and is not limited thereto. Preferably, the mass percentage of the silane coupling agent in the resin composition is 0.5% to 1.5%.

[0082] In some embodiments, the silane coupling agent may be selected from at least one compound with the following structural formulas:

[0083]

[0084] To increase the assembly operability window time of electronic components, the resin composition further includes a diluent monomer, which is an inert monomer that can complex protons generated by the photolysis of the first photoinitiator, thereby inhibiting the immediate occurrence of photolysis.

[0085] Based on the mass of the resin composition as 100%, the resin composition further includes a diluent monomer in a mass ratio of 0% to 30%, specifically 0%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 20%, or 30%, etc., and of course, other values ​​within the above range are also possible, without limitation. It is understood that the diluent monomer can participate in the polymerization reaction as a reactive monomer.

[0086] In this application, the dilutive monomer is selected from at least one compound with the following structural formulas:

[0087]

[0088] Specifically, the dilutive monomer is preferably diethylene glycol diglycidyl ether.

[0089] The polyoxygen groups in the diluent monomer of the above-mentioned structure can complex photogenerated protons, inhibiting the immediate occurrence of photopolymerization. If immediate photocuring is required, then the diluent monomer does not need to be added to the resin composition. In order to increase the operability window time of electronic components, this application adds an appropriate proportion of diluent monomer and adopts a stepwise curing process with secondary photoexcitation, which can extend the operability window time between the two light exposures to about 2 minutes.

[0090] In some embodiments, the filler is selected from at least one of silica and alumina, and the particle size of the filler is less than or equal to 20 μm. Controlling the particle size of the filler within the above range can enhance the strength of the adhesive layer, reduce the volume expansion of the adhesive layer, ensure the mechanical properties of the adhesive layer, and improve the coupling accuracy of the adhesive layer.

[0091] In some embodiments, the filler content in the resin composition is 20% to 80% by mass, specifically 20%, 30%, 40%, 50%, 60%, 70%, or 80%, etc., and is not limited thereto. Preferably, the resin composition includes 50% to 80% by mass of nano-silica particles.

[0092] In some embodiments, the additives may be selected from rheology accelerators, leveling agents, or defoamers, as needed. The rheology accelerator is primarily fumed silica. Specifically, based on 100% by weight of the resin composition, the additives include at least one of the following: 0-2% by weight of a rheology accelerator, 0-0.5% by weight of a leveling agent, and 0-0.5% by weight of a defoamer.

[0093] In the preparation process of the above resin composition, the components are mixed and then subjected to grinding, stirring, vacuum centrifugation, and degassing. When the resin composition is used as an electronic adhesive for bonding, no additional heating is required to promote curing, and the thermal stress of the cured adhesive layer is extremely low.

[0094] The resin composition can be applied to semiconductor packaging, coupling of automotive optomechanical components, fixation of optical devices, and fixation of camera modules, and is particularly suitable for the mounting and coupling of some heat-sensitive electronic components. The resin composition of this application can also form a thicker adhesive layer, or be used in light-shielding applications, especially in the field of electronic adhesives. For example, if there are gaps between the device and the substrate, uncured adhesive may flow into the light-shielding area. The resin composition of this application can achieve light-shielding area curing without baking, reducing damage to electronic components while ensuring coupling strength.

[0095] During the photocuring process, the light source required for the resin composition can be an LED light source with a wavelength of 395nm to 450nm and a light intensity of 10mW / cm². 2 ~1000mW / cm 2 The duration of light exposure can be adjusted according to the degree of curing of the resin composition.

[0096] Fourthly, this application provides an electronic device, Figure 1 This is a schematic diagram of the assembly of electronic devices provided in the embodiments of this application, such as... Figure 1As shown, the electronic device includes a substrate 10 and a light-shielding element 20 mounted on the substrate 10. There is an adhesive layer between the light-shielding element 20 and the substrate 10. The adhesive layer is made of the aforementioned resin composition. The adhesive layer includes an exposure portion 32 and a light-shielding portion 31. The light-shielding portion 31 connects the substrate 10 and the bottom surface of the light-shielding element 20. The light-shielding portion 31 is obtained by curing the resin composition after being excited by an LED light source with a wavelength of 395nm to 450nm. The exposure portion 32 connects the substrate 10 and the side surface of the light-shielding element 20. The exposure portion 32 is obtained by curing the resin composition after being excited by an ultraviolet light source with a wavelength of 360nm to 370nm.

[0097] Please continue to refer to this. Figure 1 The assembly process of electronic devices may include the following steps:

[0098] Step S10: Apply adhesive or spray adhesive according to the design of the light-shielding element 20 to form an open adhesive line. Irradiate the open adhesive line with a long-wavelength LED light source (405nm) at a light power of 200-2000mW / cm. 2 Energy 1000~5000mJ / cm 2 This achieves pre-activation of the adhesive;

[0099] In step S20, within 0.5 min to 2 min, the light-shielding element 20 is mounted on the substrate, and the thickness of the adhesive layer is controlled to be 0.1 mm to 1 mm. The adhesive layer forms visible overflow at the edge of the light-shielding element, and the width of the overflow is 2 to 5 times the thickness of the adhesive layer.

[0100] Step S30: Irradiate the adhesive wire with a short-wavelength UV light source (365nm) at a power of 200–2000 mW / cm. 2 Energy 1000~5000mJ / cm 2 After completing the curing reaction initiated by the second photoinitiator, the bonding strength between the light-shielding element and the adhesive layer in the electronic device is greater than 10 MPa after 15 minutes.

[0101] The resin composition provided in this application completes two-step curing in an environment of 18℃-28℃ and 35%-65%RH for 48 hours, which can achieve complete curing of the resin composition electronic adhesive without baking coupling. The curing reaction conversion rate of the light-shielding part of the adhesive layer is >70%, and the curing reaction conversion rate of the exposed part is >80%.

[0102] In some implementations, the adhesion strength between the light-shielding element and the substrate is ≥10 MPa when tested within 15 minutes after illumination.

[0103] like Figure 2As shown, the thickness of the exposure portion 32 is H1, and the thickness of the light-shielding portion 31 is H2, where H2 ≤ H1. The fact that the thickness of the exposure portion 32 is greater than the thickness of the light-shielding portion 31 ensures that the exposure portion 32 can further guarantee the mechanical stability of the electronic components.

[0104] In some embodiments, the curable depth of the light-shielding portion 31 of the adhesive layer formed by the resin composition is ≥2mm. Tests have shown that the curable depth of the light-shielding portion 31 can also reach 2.5mm. The curable depth of the exposed portion 32 of the adhesive layer formed by the resin composition is ≥5mm. Under sufficient light source and light intensity, the curable depth of the exposed portion can also reach 8mm.

[0105] The width of the exposed portion 32 from the edge of the light-shielding portion 31 is L1, where 2H2≤L1≤5H2. This width is the adhesive overflow width. By controlling the overflow width to be greater than the thickness of the light-shielding portion, the exposed portion can fully receive light radiation, ensuring that the heat generated by photopolymerization reaches the decomposition temperature of the thermally generated acid, thus guaranteeing effective curing of the light-shielding portion.

[0106] In some embodiments, the exposure portion 32 surrounds the edge of the light-shielding element 20 and is connected to the substrate.

[0107] The embodiments of the present invention will be further described below with reference to several examples. However, the embodiments of the present invention are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of the original claims.

[0108] The source information of each component used in the embodiments is shown in Table 1:

[0109] Table 1

[0110]

[0111]

[0112] Example 1

[0113] Weigh out 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate (CELLOXIDE 2021p), diepoxycyclohexane (CELLOXIDE 8010), epoxidized polybutadiene (EPOLEAD PB3600), and KH560 (Annegi) according to the formula in Table 2, add them to the reactor, stir at 800 rpm for 30 minutes, then add a self-made D-π-A type thionium salt cationic first photoinitiator (SbF6) to the reactor. -), 4-phenylthiophenyl-diphenylhexafluoroantimonate (Yangfan New Materials, PAG-002), 1-(2-oxo-2-phenylethyl)tetrahydro-thiophene hexafluoroantimonate (self-made), epoxy-modified silica (self-made), stirred at room temperature for 30 minutes until all components were completely dissolved, and then stirred for 2 hours at room temperature under a vacuum of -0.1 MPa and a rotation speed of 1000 rpm to obtain the resin composition of Example 1.

[0114] Examples 1-2 and Comparative Examples 1-3 were prepared according to the preparation process of Example 1. The amount of components added in each example is detailed in Table 2.

[0115] Table 2. Component addition amounts for each embodiment

[0116]

[0117] The " / " indicates that the component was not added.

[0118] First, the verification scheme for the curability depth of the resin composition under light exposure conditions:

[0119] 1. The resin composition prepared according to the examples and comparative formulations is filled into a tubular mold using a scraper. The tubular mold is made of polytetrafluoroethylene and has an inner diameter of 4 mm. The filling depth of the resin composition is 10 mm to 15 mm.

[0120] 2. Using a wavelength of 425nm, the light intensity is 200mW / cm². 2 LED light for 20 seconds.

[0121] 3. Use a steel needle to eject the glue column and demold it. Scrape off any uncured or softly cured parts of the sample and test the depth of its cured state.

[0122] Figure 3a This is a schematic diagram showing the cured state of the samples prepared in the embodiments and comparative examples of this application, as shown below. Figure 3a As shown, the resin composition of Example 1 can be cured to a depth ≥5mm under light conditions, while the resin composition of Example 2 can be cured to a depth of 8mm under light conditions. Figure 3b As shown, the resin composition of Comparative Example 1 forms a glue column that cannot be cured, the resin composition of Comparative Example 2 forms a glue column with a curable depth of less than 1 mm, and the resin composition of Comparative Example 3 forms a glue column with a curable depth of about 4 mm, but the cured glue column is relatively soft.

[0123] Second, the verification scheme for the curability depth of the resin composition under light-shielding conditions:

[0124] 1. Add the resin composition prepared according to the examples and comparative formulations into the syringes respectively, and purge the gas in the syringes to ensure that there are no air bubbles in the resin composition.

[0125] 2. Place the small piece of paper between the two ABS boards, ensuring there is a gap between them. Figure 4 As shown.

[0126] 3. Clamp the two ABS sheets together, use a syringe to apply the resin composition adhesive to the lower ABS sheet, and ensure that the adhesive adheres tightly to the upper ABS sheet.

[0127] 4. Using a wavelength of 425nm, the light intensity is 300mW / cm². 2 After 10 seconds of LED illumination, the upper ABS plate is lifted, and the uncured or softly cured parts of the sample are scraped off. Then, the curing status of the light-shielded area of ​​the sample is observed.

[0128] Figure 5 This is a schematic diagram showing the cured state of the samples prepared in the embodiments and comparative examples of this application, as shown below. Figure 5 As shown, under partial light-shielding conditions, the curable depth of the light-shielded portion of the adhesive layer formed by the resin composition of Example 1, when excited by an LED light source with a wavelength of 425 nm, is ≥2 mm. Specifically, the curable depth of the light-shielded portion of the adhesive layer formed by the resin composition of Example 1 is approximately 2 mm, and the adhesive layer can achieve complete curing. The curable depth of the light-shielded portion of the adhesive layer formed by the resin composition of Example 2 is approximately 2.5 mm, and the adhesive layer can achieve complete curing.

[0129] Under the same conditions, the light-shielding portion of the adhesive layer formed by the resin composition of Comparative Example 1 could not be cured. The light-shielding portion of the adhesive layer formed by the resin composition of Comparative Example 2 was softer after curing and not fully cured, with a thickness of about 1 mm for the softer cured portion. The light-shielding portion of the adhesive layer formed by the resin composition of Comparative Example 3 was also softer after curing and not fully cured, with a thickness of about 1.5 mm for the softer cured portion.

[0130] Third, a two-step curing verification scheme for the resin composition under light-shielding conditions:

[0131] Example 3

[0132] Weigh the following according to the formula in Table 3: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate (TTA21P, Tetel), 3,3'-(oxydimethylene)-bis-3-ethyloxetane (TCM201, Qiangli Company), diepoxycyclohexane (TTA800, Tetel), 3-ethyl-3-[4-[(3-ethyloxetane-3-yl)methoxy]butoxymethyl]oxetane (TCM218, Qiangli Company), epoxidized polybutadiene, 3-ethyl-3-[(benzyloxy)methyl]oxetane (TCM104, Qiangli Company), 2,2'- [Oxybis(2,1-ethyleneoxymethylene)]diethylene oxide (EGDEO, Qiangli Company), KH560 (Annegi) were added to the reactor and stirred at 800 rpm for 30 minutes. Then, D-π-A type thionium salts (self-made), 4-phenylthiophenyl-diphenylhexafluoroantimonate, tetrahydro-1-(2-oxo-2-phenylethyl)thiophene hexafluoroantimonate, and 4-hydroxyphenylmethylbenzylhexafluoroantimonate were added to the reactor. The mixture was stirred at room temperature for 30 minutes until all the thionium salts were completely dissolved. Then, silica micron powder, BYK-307, BYK-055, and copper phosphate (Annegi) were added. The mixture was stirred for another 2 hours at room temperature under a vacuum of -0.1 MPa and a rotation speed of 1000 rpm to obtain the resin composition.

[0133] The component addition amounts for each embodiment prepared according to the preparation process of Example 3 are detailed in Table 3.

[0134] Table 3. Component addition amounts for each embodiment

[0135]

[0136] Fourth, the workability window time verification scheme for the resin composition.

[0137] 1. The resin composition prepared according to the formulation in the example is coated onto a polytetrafluoroethylene sheet, and the resulting adhesive layer has a length of 10 cm and a thickness of 1 mm;

[0138] 2. Using a wavelength of 425nm, the light intensity is 300mW / cm². 2 Illuminate the sample under LED light for 15 seconds and observe the viscosity change while stirring.

[0139] According to the test data, the operating window of the resin composition in Example 3 was >1.5 min, the operating window of the resin composition in Example 4 was >2 min, the operating window of the resin composition in Example 5 was about 30 s, the operating window of the resin composition in Example 6 was about 15 to 20 s, and the operating window of the resin composition in Example 7 was about 4 min.

[0140] Therefore, it can be seen that, due to the addition of an appropriate amount of diluent monomer in Example 7, the diluent monomer can delay the curing time of the resin composition system under weak light intensity and low energy (10-100mW / cm²). 2 Delayed curing after the first excitation can be achieved at 500-5000mJ, and the operability window time can be maintained at 1min to 5min. When the resin composition is excited by the light source a second time, the curing rate can reach more than 79%.

[0141] Fifth, Photo-DSC validation protocol for resin compositions.

[0142] Photo-DSC (DSC 500C, Yanjin Instruments) was used to test the photopolymerization process of the resin composition. This primarily involved recording the rate and total heat released after the ring-opening of the oxobutane-based diluent monomer and the epoxy resin (epoxycyclohexane). The conversion rate was calculated based on the theoretically calculated heat released after all the monomers underwent ring-opening. Furthermore, the rate of heat release is also related to the polymerization rate. Therefore, Photo-DSC can be used to test relevant parameters of monomer photopolymerization. Although different formulations contain different types of epoxy resin and diluent monomers, the total heat released allows for a rough comparison of the polymerization effect, including the polymerization rate and relative monomer conversion rate.

[0143] 1. First, the four samples were irradiated for 30 seconds each using a 405nm light source with a light intensity of 50%.

[0144] 2. After 25 minutes, irradiate with a 365nm light source at 100% intensity for 200 seconds.

[0145] Table 4. Parameters and Calculation Data of the Polymerization Conversion Rate Validation Scheme in the Examples

[0146] Process parameters Example 3 Example 4 Example 5 Example 6 Example 7 <![CDATA[After a single irradiation (405 nm LED, 20 mW / cm 2 ) for 100 s]]> 4.8％ 11.6％ 15.7％ 11.6％ 3.1％ 200s after one irradiation 7.3％ 17.1％ 21.2％ 17.9％ 6.5％ 300s after one irradiation 9.2％ 22.6％ 24.7％ 22.3％ 8.5％ 400s after one irradiation 11.3％ 25.6％ 27.5％ 25.9％ 10.1％ <![CDATA[After secondary irradiation (365nm LED, 80mW / cm 2 ) for 50 s]]> 44.4％ 57.5％ 48.8％ 54.7％ 45.2％ 100 seconds after the second irradiation 65.2％ 71.6％ 57.1％ 67.8％ 71.5％ 200s after the second irradiation 79％ 85.8％ 65.2％ 79.2％ 82.4％

[0147] Figure 6a This is a heat flow curve of the resin composition in an embodiment of this application. Figure 6b This is a graph showing the polymerization conversion rate of the resin composition in the embodiments of this application, such as... Figure 6a and Figure 6b As shown, all samples polymerized under initial irradiation with a 50% intensity 405nm LED light source, but the polymerization conversion rates differed under the same irradiation time. Example 7 showed a very low polymerization conversion rate under 50% 405nm LED light source irradiation, but the conversion rate increased significantly when irradiated with a 100% intensity 365nm light source. This indicates that the sample in Example 7 is not sensitive to initiation by lower energy light sources. This is because the resin composition formulation of Example 7 contains a lower mass content of the first photoinitiator sensitive to LED light sources. Therefore, the resin composition formulation of Example 7 is more suitable for assembly environments requiring a longer operational window.

[0148] According to the test data of Examples 5, 6, and 7, the polymerization conversion rate of Examples 5 and 6 under 50% 405nm LED light source irradiation is significantly improved compared to Example 7. This indicates improved sensitivity to lower energy light sources. This is because an appropriate amount of the first photoinitiator was added in Examples 5 and 6, allowing for further polymerization to be completed under 100% 365nm light source irradiation after excitation by a low-energy LED light source. Meanwhile, under continuous 405nm light irradiation, the relative polymerization conversion rate of Example 6 is lower than that of Example 5.

[0149] According to the data in Table 4, after the resin compositions of Examples 3-6 of this application are irradiated by an LED light source, the addition of a first photoinitiator, a thionium salt cationic type sensitive to LED light, allows the byproducts from the decomposition of the first photoinitiator to act as photosensitizers, resulting in the entire resin composition system emitting light. This functions as a secondary light source, allowing light to diffuse into the shaded area and promoting the curing of the resin composition in the shaded area. Further irradiation with a 365nm light source can achieve a curing rate of over 65% for the resin composition.

[0150] According to the data in Table 4, the resin composition showed improved performance after 100 seconds of the first irradiation (405 nm, 200 mW / cm²). 2 The resin composition has a latency period of more than 2 minutes. After the second irradiation, the bonding strength between the cured adhesive layer and the electronic components can reach more than 10 MPa.

[0151] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A resin composition cured by LED light excitation, characterized in that, The resin composition comprises, by weight percentage: The composition includes: 0.1%–2% of a thioonium salt cationic primary photoinitiator, 0.1%–2% of a secondary photoinitiator, 0.5%–5% of a thermogenic acid generator, 20%–60% of a main resin, 2%–10% of a functional resin, 0%–5% of a silane coupling agent, and 20%–80% of fillers and additives. Under partial light-shielding conditions, when the adhesive layer formed by the resin composition is excited by an LED light source with a wavelength of 395nm to 450nm, the curability of the light-shielded portion of the adhesive layer is ≥2mm, and the curability depth of the exposed portion of the adhesive layer is ≥5mm.

2. The resin composition according to claim 1, characterized in that, The structural formula of the thionium salt-based cationic first photoinitiator is shown in Formula I: In equation I, X1 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them.

3. The resin composition according to claim 1, characterized in that, The second photoinitiator is selected from at least one of the compounds shown in Formula II-1 and Formula II-2: In equations II-1 and II-2, X2 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them.

4. The resin composition according to claim 1, characterized in that, The thermal acid-generating agent is selected from at least one of the compounds shown in Formula III-1, Formula III-2, and Formula III-3: In equations III-1, III-2, and III-3, X3 — The anion is selected from PF6. — SbF6 — AsF6 — B(C6F5)4 — (CF3SO2)2N — One of them.

5. The resin composition according to claim 1, characterized in that, The main resin is an alicyclic epoxy resin.

6. The resin composition according to claim 5, characterized in that, The alicyclic epoxy resin is selected from compounds with the following structures:

7. The resin composition according to claim 1, characterized in that, Based on 100% by weight, the resin composition further comprises 0-30% by weight of a dilutive monomer, wherein the dilutive monomer is selected from at least one compound with the following structural formulas:

8. The resin composition according to claim 1, characterized in that, The silane coupling agent comprises at least one compound with the following structural formula:

9. The resin composition according to claim 1, characterized in that, The resin composition satisfies at least one of the following characteristics: a. The functional resin includes at least one of polymeric epoxy resin, epoxidized polybutadiene, and polyester polyol; b. The filler is selected from at least one of silica and alumina, and the particle size of the filler is less than or equal to 20 μm; c. The resin composition comprises 50% to 80% by weight of nano-silica particles; d. Based on the mass of the resin composition, the additives include at least one of the following: a rheology accelerator at a mass percentage of 0-2%, a leveling agent at a mass percentage of 0-0.5%, and a defoamer at a mass percentage of 0-0.5%.

10. The resin composition according to claim 1, characterized in that, The light intensity of the LED light source that excites the curing of the resin composition is 10 mW / cm². 2 ~1000mW / cm 2 .

11. An electronic device, characterized in that, The device includes a substrate and a light-shielding element mounted on the substrate. An adhesive layer is provided between the light-shielding element and the substrate. The adhesive layer is made of the resin composition according to any one of claims 1 to 10. The adhesive layer includes an exposure portion and a light-shielding portion. The light-shielding portion connects the substrate and the bottom surface of the light-shielding element, and is obtained by curing the resin composition after excitation by an LED light source with a wavelength of 395 nm to 450 nm. The exposure portion connects the substrate and the side surface of the light-shielding element, and is obtained by curing the resin composition after excitation by an ultraviolet light source with a wavelength of 360 nm to 370 nm.

12. The electronic device according to claim 11, characterized in that, The thickness of the exposed portion is H1, and the thickness of the light-shielding portion is H2, where H2 ≤ H1.

13. The electronic device according to claim 12, characterized in that, The distance between the exposed portion and the edge of the light-shielding portion is L1, where 2H2≤L1≤5H2.

14. The electronic device according to claim 11, characterized in that, The bonding strength between the light-shielding element and the substrate is ≥10 MPa.

15. The electronic device according to claim 11, characterized in that, The exposure portion surrounds the edge of the light-shielding element and is connected to the substrate.

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