TWI901018B - Development type packaging adhesive composition and light-emitting diode packaging parts - Google Patents

Abstract

A developing type encapsulant composition includes an acrylic resin, a fluorene cardo derivative containing polyepoxy groups, a multifunctional acrylic monomer, a hydrophilic acrylic monomer, an epoxysilane monomer having an epoxy functional group, a photoinitiator, and a solvent. The acrylic resin has an acid value of 90-110 and a content of 30-50 wt %, the polyepoxy-containing fluorene cardo derivative has a content of 1-4 wt %, the multifunctional acrylic oligomer has a content of 1-6 wt %, the hydrophilic multifunctional acrylic monomer has a content of 1-4 wt %, the epoxysilane monomer has a content of 0.1-1 wt %, and the viscosity of the developing encapsulating adhesive composition at 25° C. is no greater than 15 cps. The present invention also provides a light-emitting diode package using the developing encapsulating adhesive composition as an encapsulating material.

Description

Development type packaging adhesive composition and light-emitting diode packaging parts

The present invention relates to a packaging adhesive composition and a light-emitting packaging component, particularly a low-viscosity developing type packaging adhesive composition and a light-emitting diode package containing the developing type packaging adhesive composition.

Light-emitting diodes (LEDs) have been widely used in a variety of applications in recent years due to their advantages such as energy saving, high efficiency, high brightness, long life, and fast response time. These include outdoor and indoor lighting, billboards, mobile phones, televisions, car lights, and other products with different uses. As mentioned above, LED chips are assembled with other components to form products that can be applied to different fields. For example, in the case of using LEDs as a backlight source for a television, a plurality of LEDs that can emit light of different colors (R, G, B) are packaged on a circuit board with a control circuit that can drive and control these LEDs to obtain a backlight source that can be applied to the television. In order to achieve full-color display, LEDs that can emit the three primary colors (R, G, B) are usually packaged to achieve the purpose of color adjustment.

However, because LEDs of different colors have different luminous efficiencies, the area and height of these LEDs are typically adjusted. (For example, red LEDs, due to their lower luminous intensity and efficiency, require a larger area and a taller height (approximately 6-7μm), while blue LEDs, due to their higher luminous efficiency and brightness, require a smaller area and a shorter height (approximately 4-5μm).) This allows LEDs of different colors to have comparable luminous intensity. Therefore, when bare LEDs of different colors are connected to the circuit board and then packaged with encapsulant, the height of the LEDs and the overall flatness of the package are considered, ensuring the overall height of the encapsulant is no less than 10μm.

The encapsulation adhesive used to encapsulate these LEDs typically utilizes existing transparent photoresist. This transparent photoresist is applied to cover the LED chips connected to the circuit board, and then, through illumination and development, forms a uniformly high (no less than 10μm) encapsulation layer that covers the LED chips. However, because the encapsulation layer requires a relatively high height (no less than 10μm), it is prone to development problems during the development process. Furthermore, the high viscosity of typical transparent photoresist materials (>70cps at 25°C) also hinders the coating process.

Therefore, the object of the present invention is to provide a developing type encapsulating adhesive composition that is easy to apply and has high developing properties.

Therefore, the developer-type encapsulant of the present invention comprises: an acrylic resin, a fluorene cardo derivative containing polyepoxy groups, a multifunctional acrylic oligomer, a hydrophilic multifunctional acrylic monomer, an epoxysilane monomer having an epoxy functional group, a photoinitiator, and a solvent.

The acid value of the acrylic resin is between 90 and 110. Based on 100 weight percent of the developing encapsulating adhesive composition, the content of the acrylic resin is between 30 and 50 weight percent, the content of the polyepoxy-containing fluorene cardo derivative is between 1 and 4 weight percent, the content of the multifunctional acrylic oligomer is between 1 and 6 weight percent, the content of the hydrophilic multifunctional acrylic monomer is between 1 and 4 weight percent, and the content of the epoxysilane monomer is between 0.1 and 1 weight percent. Furthermore, the viscosity of the developing encapsulating adhesive composition at 25° C. is no greater than 15 cps.

Another object of the present invention is to provide a light-emitting diode package.

Therefore, the LED package of the present invention includes a circuit board, a plurality of LEDs formed on the circuit board, and a plurality of packaging layers respectively covering the LEDs.

The packaging layers are formed by cross-linking the aforementioned developing type packaging adhesive composition, and the visible light transmittance of the packaging layer is not less than 95%.

The present invention has the advantage that, by combining the components and content ratios of the developer-type encapsulant, the developer-type encapsulant exhibits excellent developability after exposure to light, thereby improving the problem of unclean thick film development. Furthermore, because the developer-type encapsulant has a relatively low viscosity, it also exhibits improved usability in coating processes.

Before describing the present invention in detail, please note that similar components are numbered the same throughout the following description. The relevant technical content, features, and functions of the present invention will be clearly presented in the following detailed description of the embodiments with reference to the accompanying drawings. Furthermore, it should be noted that the drawings of the present invention merely illustrate the relative structural and/or positional relationships between components and do not reflect the actual dimensions of the components.

The present invention's developing encapsulant composition can be used in a yellow light process. One embodiment of the developing encapsulant composition comprises: an acrylic resin, a fluorene cardo derivative containing polyepoxy groups, a multifunctional acrylic oligomer, a hydrophilic multifunctional acrylic monomer, a multifunctional thiol compound, an epoxysilane monomer containing epoxy functional groups, a photoinitiator, and a solvent.

Wherein, based on the weight percentage of the developing type encapsulating adhesive composition as 100wt%, the content of the acrylic resin is between 30wt% and 50wt%, the content of the polyepoxy-containing cardo fluorene derivative is between 1wt% and 4wt%, the content of the multifunctional acrylic oligomer is between 1wt% and 6wt%, the content of the hydrophilic multifunctional acrylic monomer is between 1wt% and 4wt%, the content of the multifunctional thiol compound is between 0.1wt% and 1wt%, the content of the epoxysilane monomer having an epoxy functional group is between 0.1wt% and 1wt%, and the content of the photoinitiator is between 1wt%. Moreover, the viscosity of the developing type encapsulating adhesive composition at 25°C is not greater than 15cps.

Specifically, the acrylic resin is an acrylic resin having carboxylic acid groups, and the acid value (AV) of the acrylic resin is between 90 and 110. Preferably, the molecular weight of the acrylic resin is between 3000 and 4000. In this embodiment, the acrylic resin is selected from Nippon Kayaku and has an acid value of 90-100 mgKOH/g.

A cardo fluorene derivative is a compound with a stereostructure formed by combining a fluorene derivative with various aromatic rings. In this embodiment, the polyepoxy-functional cardo fluorene derivative can be used to adjust post-development flatness and thermal crosslinking. However, excessive amounts can result in unclean development. Preferably, the content of the polyepoxy-functional cardo fluorene derivative is less than 4 wt%.

In some embodiments, the fluorene cardo derivative containing polyepoxy functional groups is a fluorene cardo derivative having a diepoxy functional group.

Specifically, the cardo fluorene derivative having a bisepoxide functional group in this embodiment of the present invention is selected from: 9,9-Bis[4-(2-oxiranemethyloxy)phenyl]fluorine, which has the structure shown in the following formula (1). (1)

The multifunctional acrylic oligomer can be used to increase crosslinking speed, improve hardness after crosslinking, and help improve resistance to staining. Preferably, the multifunctional acrylic oligomer is selected from multifunctional acrylic oligomers having 5 to 6 reactive functional groups.

The hydrophilic multifunctional acrylic monomer can be used to increase hydrophilicity to aid development. Preferably, the hydrophilic multifunctional acrylic monomer is selected from hydrophilic multifunctional acrylic monomers having a hydrophilic ethoxy (EO) repeating unit number of not less than 20. More preferably, the hydrophilic multifunctional acrylic monomer is selected from multifunctional hydrophilic acrylic monomers having 5-6 reactive functional groups, such as DP(EO)nPA, n>20, or DP(EO)nHA, n>20. Specifically, the hydrophilic multifunctional acrylic monomer is selected from the structure of the following formula (2), and the number of hydrophilic segments (EO) in the structure: a+b+c+d+e+f is not less than 20. (2)

The multifunctional thiol compound can increase crosslinking density and improve resistance to staining and adhesion, as well as reduce initial yellowing. Preferably, the multifunctional thiol compound is selected from pentaerythritol tetrakis(3-hydroxybutyrate) having four reactive functional groups, as shown in the structure of formula (3) below. (3)

The epoxy-functional epoxysilane monomer is used to increase weather resistance and adhesion to other substrates (such as glass), and can help high-temperature crosslinking and prevent coating cracking. Specifically, the epoxy-functional epoxysilane monomer has the structure of the following formula (4). (4)

Upon exposure to light, the photoinitiator generates free radicals, which crosslink the reactive acrylic monomers. Preferably, the photoinitiator is composed of a single photoinitiator that absorbs the same wavelength range as the irradiated light, or a combination of at least two photoinitiator components that absorb different wavelengths. In this embodiment, the photoinitiator comprises two photoinitiator components, TPO and IRGACURE OXE-01, that absorb different wavelengths, with concentrations of 0.1-0.5 wt% and 1-2 wt%, respectively. TPO primarily absorbs in the 360-400 nm wavelength range, while IRGACURE OXE-01 primarily absorbs in the 280-400 nm wavelength range.

The solvent, which accounts for 50-60% by weight of the developer-type encapsulant composition, is used to dissolve the components and adjust the developer-type encapsulant composition to the desired viscosity. Furthermore, to prevent the solvent's low boiling point from causing rapid volatility during the coating process, which could impact the process, or a high boiling point from hindering subsequent thermal removal, the solvent is selected from a non-protic solvent with a boiling point of no less than 120°C and no more than 180°C. In this embodiment, the solvent is selected from 1,2-propylene glycol methyl ether acetate (PGMEA).

Furthermore, the developer-type encapsulant composition of the present invention may also contain additives such as a leveling agent, a defoaming agent, and/or a light stabilizer to further improve the defoaming and flatness of the film after coating, and to enhance the lightfastness and yellowing resistance of the encapsulating layer after formation. Specifically, the total content of these additives is no more than 1.5 wt %. Preferably, the total content of these additives is between 0.1 and 0.5 wt %. Since the selection of these additives (leveling agent, defoaming agent, and light stabilizer, etc.) is well known to those skilled in the art, no further explanation is given. In this embodiment, the leveling agent can be selected from a silicone-based leveling agent or an acrylic-based leveling agent, and the defoaming agent can be selected from a silicone-based defoaming agent.

The developer-type encapsulating adhesive composition of the present invention has low viscosity and good developability. Therefore, it can be formed into a film by coating (roll coating, spin coating, etc.). Subsequently, in conjunction with the lithography process, an encapsulation layer formed by crosslinking and curing the developer-type encapsulating adhesive composition can be formed at a predetermined position.

Referring to FIG. 1 , the present invention is used to package LED chips 102 of varying heights on a circuit board 101 having a control IC 200 using the developer-type packaging adhesive assembly. As shown in FIG. 1 , a plurality of packaging layers 103 are formed, each corresponding to and covering the LED chips 102. The packaging layers 103 have substantially the same height, forming a LED package component.

The packaging method first utilizes a coating method to coat the developer-type packaging adhesive composition described in the embodiment on the surface of the circuit board 101 to form a wet film covering the circuit board 101 and the light-emitting diode chips 102, thereby obtaining a first semi-finished product.

Next, the first semi-finished product is subjected to a first pre-bake to remove the solvent of the wet film to form a dry film, thereby obtaining an intermediate.

Next, the dry film is exposed with a patterned mask. The dry film corresponding to the positions covering the LED chips 102 is exposed, and the remaining positions are blocked with a mask to form non-exposure areas, thereby obtaining a second semi-finished product.

The second semi-finished product is developed to remove the dry film in the non-exposed area to obtain a third semi-finished product.

Finally, the dry film of the third semi-finished product is heated and post-cured to form a packaging layer 103 covering the LED chips 102, thereby obtaining the LED package shown in FIG. 1 .

The following experimental examples 1 to 13 and comparative examples are used to illustrate the composition of the developing type packaging adhesive of the present invention, and the characteristics of the packaging layer 103 formed by the above-mentioned method in these experimental examples 1 to 13 and comparative examples are measured.

The comparative example is a conventional developing photoresist.

The compositions used in Experimental Examples 1 to 13 are as follows: Components Brand A Acrylic resin Nippon Chemicals B Fluorencadol derivatives Sun Moon Star Technology has the structure of formula (1) above. C Multifunctional acrylic monomer Jin Youli D Hydrophilic multifunctional acrylic monomer Guojing Chemical has the structure of formula (2) above. E Multifunctional thiol compounds Showa Denko As shown in the above formula (3) F Epoxysilane monomer Momentive has the structure of formula (4) above. G Leveling agent DIC H1 Photoinitiator BASF H2 Photoinitiator BASF I Solvent (PGMEA) J 6-reactive functional group acrylic monomer (DPHA)

The compositions and contents of Experimental Examples 1 to 13 are shown in Table 1. Composition Experimental Example 1 2 3 4 5 6 7 8 9 10 11 12 13 A 33 30 50 33 33 33 33 33 33 33 33 33 33 B 3.6 3.6 3.6 1.0 4.0 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 C 5.3 5.3 5.3 5.3 5.3 1.0 6.0 6.0 5.3 5.3 5.3 5.3 5.3 D 1.8 1.8 1.8 1.8 1.8 1.8 1.8 3.6 1.8 1.8 1.8 1.8 0 E 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.8 0 0.4 F 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 1.0 0 0.7 0.7 0.7 G 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 H1 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 H2 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 I 53.5 56.5 36.5 56.1 53.1 57.8 52.8 51 53.2 54.2 53.1 53.9 53.5 J 0 0 0 0 0 0 0 0 0 0 0 0 1.8

Next, the developer-type encapsulant compositions of Experimental Examples 1-13 and the comparative example were applied to an alkali-free glass surface using a spin coating method (spin speed: 200 rpm, spin time: 10 seconds). The alkali-free glass coated with the developer-type encapsulant compositions was then baked in an 80°C oven for 10 minutes to remove the solvent, forming a dry film. The dry films were then exposed using i-line at an exposure dose of 80-110 mJ/ ^cm² using masks with different resolution patterns (Line/Space (L/S) = 20/20μm, 30/30μm, 40/40μm, and 50/50μm). After exposure, the films were developed at room temperature (spray pressure 0.8 kgf/cm ² , developer: KOH (450 ppm), development time: 60 seconds). After development, they were placed in a 180°C oven for 30 minutes for post-curing, yielding experimental specimens 1-13 and comparative specimen 1.

Test specimens 1-13 and comparative specimen 1 were then tested for properties such as developing resolution, developing resistance, transmittance, and yellowing. The relevant test results are summarized in Table 2.

The weathering transmittance of the experimental specimen 1 and the comparative specimen at all wavelengths (380-780nm) are shown in Figures 2 and 3, respectively. The weathering yellowing results of the experimental specimen 1 and the comparative specimen are shown in Figures 4 and 5, respectively.

Table 2 Composition Experimental specimens Comparison test pieces 1 2 3 4 5 6 7 8 9 10 11 12 13 resolution ◎ ○ ◎ ○ ╳ ◎ ◎ ◎ ◎ ◎ ○ ◎ ╳ ╳ Resistance to staining ◎ ○ ◎ ○ ◎ ╳ ╳ ╳ ◎ ◎ ◎ ╳ ◎ ◎ Penetration ◎ ○ ○ ◎ ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ◎ Penetrating yellowing ◎ ○ ○ ◎ ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ○ Weather penetration resistance ◎ ○ ○ ◎ ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ○ Weathering and yellowing resistance ◎ ○ ○ ◎ ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ○ Weather-resistant appearance ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ╳ ◎ ◎ ◎ ◎

Resolution: Use a laser microscope (model VK-X3000, manufactured by Keyence) to observe the imaging resolution (Line/Space) to confirm the imaging condition. ◎ L/S: 40um / 40um, 30um / 30um, 20um / 20um are fully developed ○ L/S = 50um / 50um is fully developed ╳ L/S = 50um / 50um is not fully developed

Anti-corrosion: Use a laser microscope (model VK-X3000, manufactured by Keyence) to observe whether the surface of the package layer has been corroded by alkaline solution. ◎ No corrosion ○ Slight pitting on the surface ╳ Severe pitting, coating peeling

Transmittance: Exposure was performed without placing a mask, and the dry film thickness after exposure was confirmed to be 10-12 μm. The average transmittance of the dry film after exposure was measured at 380-780 nm using a visible-near-infrared spectrometer (model U4100, manufactured by Hitachi High-tech). ◎ Transmittance ≧ 95% ○ 95%＞ Transmittance ≧ 90% ╳ Transmittance＜ 90%

Transparent yellowing: Exposure was performed without a mask. The dry film thickness after exposure was confirmed to be 10-12 μm. The CIE Lab b* of the dry film after exposure was measured at 380-780 nm using a visible-near-infrared spectrometer (Model U4100, manufactured by Hitachi High-tech). ◎ b* < 0.7 ○ 1.1 > b* ≧ 0.7 ╳ b* ≧ 1.1

Weathering penetration and yellowing resistance: Test the specimens under the following weathering conditions before performing penetration and yellowing tests. Weathering conditions: (1) 60℃/90%; 500 hours; (2) -40℃＜->80℃, 200 cycles, stay at -40℃ for 30 minutes, and then heat up to 80℃ in 30 minutes for one cycle; (3) 85℃; 500 hours; (4) 500W halogen lamp illumination; 500 hours; Among them, Weathering transmittance: ◎ After the above 4 weathering conditions, the transmittance is ≥95%, ○ After the above 4 weathering conditions, at least one of the transmittances is between: 95%＞transmittance≧90%; Weathering yellowing: ◎ After the above 4 weathering conditions , b*＜0.7, ○ After the above 4 weathering conditions, 1.1＞b*≧0.7, ╳ After the above 4 weathering conditions, at least one of the b*≧1.1

Weathering appearance: Observe the coating appearance of the test piece after the weathering test to confirm whether there is any damage or cracking. ◎ No cracking or damage ╳ Cracks or damage

As shown in Figures 2 and 3, the light transmittance of the experimental specimen 1 in this case remained above 97% after various weathering tests, while the light transmittance of the comparative specimen decreased to less than 96% after the light exposure test. Furthermore, the yellowing results in Figures 4 and 5 show that the b* value of the experimental specimen 1 remained similar to that before the weathering test after various weathering tests, while the b* value of the comparative specimen increased significantly after the light exposure test. Furthermore, the results for specimens 1, 6, 7, and 8 in Table 2 indicate that the multifunctional acrylic oligomer (C) exhibits better yellowing resistance when its content is greater than 1wt% and less than 6wt%. The results of test pieces 12 and 13 show that the absence of the hydrophilic multifunctional acrylic monomer (D) affects the developability, and the absence of the multifunctional thiol compound (E) results in poor developability. Furthermore, test piece 5 shows that a high content of the fluorenyl cardol derivative (B) affects the developability. Test piece 10 shows that the absence of the epoxysilane monomer (F) in the composition affects the weathering appearance. The results of the other test pieces show that when the proportions of the various components are within the range of this case, they all exhibit good developability, penetration, and weathering resistance, and are more suitable for thick film development.

In summary, the developer-type encapsulant composition of the present invention utilizes components, their ratios, and viscosity control, making it suitable for screen printing processes. Due to its excellent developability, it can achieve good resolution even when applied to thick films. Furthermore, the encapsulation layer 103 formed after curing by the developer-type encapsulant composition exhibits excellent transparency, maintains good optical properties even after weathering, and resists yellowing after exposure to light, without affecting the color of light emitted by the encapsulated LED chip 102. Therefore, the objectives of the present invention are effectively achieved.

However, the above description is merely an example of the present invention and should not be used to limit the scope of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application and the content of the patent specification of the present invention are still within the scope of the present patent.

101                Circuit board 102                LED chip 103                Package layer 200                Control IC

Other features and benefits of the present invention are clearly illustrated in the accompanying drawings, in which: FIG1 is a schematic diagram illustrating a light-emitting diode package component encapsulated using the present invention's developing encapsulation adhesive; FIG2 is a weathering transmittance graph illustrating transmittance measurement results of experimental specimen 1 under different weathering conditions; FIG3 is a weathering transmittance graph illustrating transmittance measurement results of comparative specimens under different weathering conditions; FIG4 is a weathering yellowing graph illustrating yellowing (b*) measurement results of experimental specimen 1 under different weathering conditions; and FIG5 is a weathering yellowing graph illustrating yellowing (b*) measurement results of comparative specimens under different weathering conditions.

101 Circuit board 102 LED chip 103 Package layer 200 Control IC

Claims (10)

A developing type encapsulating adhesive composition comprises: an acrylic resin, a polyepoxy-containing fluorene cardo derivative, a multifunctional acrylic oligomer, a hydrophilic multifunctional acrylic monomer, an epoxysilane monomer having an epoxy functional group, a photoinitiator, and a solvent. The acrylic resin has an acid value of 90-110, and based on 100 wt% of the developing type encapsulating adhesive composition, the content of the acrylic resin is 30-50 wt%, the content of the polyepoxy-containing fluorene cardo derivative is 100 wt%, and the content of the polyepoxy-containing fluorene cardo derivative is 100 wt%. The content of the cardo) derivative is between 1-4 wt%, the content of the multifunctional acrylic oligomer is between 1-6 wt%, the content of the hydrophilic multifunctional acrylic monomer is between 1-4 wt%, the content of the epoxysilane monomer is between 0.1-1 wt%, and the viscosity of the developing encapsulating adhesive composition at 25°C is not greater than 15 cps. The developing type encapsulating adhesive composition as claimed in claim 1, wherein the polyepoxy-containing fluorene cardo derivative is a bisepoxy-containing fluorene cardo derivative, and the number of functional groups of the polyfunctional acrylic monomer and the hydrophilic polyfunctional acrylic monomer is between 5 and 6. The developing type encapsulating adhesive composition as described in claim 1, wherein the hydrophilic multifunctional acrylic monomer is a hydrophilic acrylic monomer having multiple reactive functional groups, and the hydrophilic acrylic monomer has at least 20 ethoxy (EO) repeating units. The developing type encapsulant composition as claimed in claim 1 further comprises a multifunctional thiol compound, wherein the content of the multifunctional thiol compound is between 0.1 and 1 wt%. The developer-type encapsulant composition as claimed in claim 1, wherein the boiling point of the solvent is between 120°C and 150°C. The developing encapsulant composition as described in claim 1 further comprises an additive, wherein the additive may be at least one of a self-leveling agent, a defoaming agent, and a light stabilizer, and the total content of the additive is not more than 1.0 wt%. The developing type encapsulant composition as described in claim 1, wherein the photoinitiator can absorb ultraviolet light in at least two different wavelength ranges, and the content of the photoinitiator is between 1 and 3 wt%. The developing type encapsulant composition as described in claim 1, wherein the content of the multifunctional acrylic oligomer is greater than 1 wt% and less than 6 wt%, and the content of the polyepoxy-containing fluorene cardo derivative is greater than or equal to 1 wt% and less than 4 wt%. A light-emitting diode package comprises a circuit board, a plurality of light-emitting diodes formed on the circuit board, and a plurality of packaging layers respectively encapsulating the light-emitting diodes, wherein the packaging layers are formed by light-crosslinking the developing type packaging adhesive composition as described in claim 1, and the visible light transmittance of the packaging layers is not less than 95%. The light-emitting diode package as described in claim 9, wherein the vertical height distance between the top surfaces of the packaging layers and the surface of the circuit board is not less than 10 μm.