TWI902358B - Adhesive composition and adhesive film structure for mass transfer - Google Patents

Abstract

An adhesive composition and an adhesive film structure for mass transfer are provided. The adhesive composition for mass transfer includes a silicone resin, a crosslinking agent, an anchoring agent and a catalyst. Based on the adhesive composition for mass transfer as 100 wt%, the silicon resin is 95 wt% to 99 wt%. A weight ratio between the crosslinking agent, the anchoring agent and the catalyst is 1:2:4. As such, an adhesive layer including the adhesive composition for mass transfer can have less release strength with a releasing layer, greater heat resistance temperature and greater transmittance for light with a specific wavelength.

Description

Adhesive compositions and film structures for mass transfer

This invention relates to an adhesive composition and a film structure, and more particularly to an adhesive composition and a film structure for mass transfer.

Mass transfer is a key technology for the mass production of mini LEDs and micro LEDs, and it is also a significant factor affecting process yield. Mass transfer is the process of transferring LED chips onto a target substrate. The steps of mass transfer include first attaching a mass transfer film (mass transfer adhesive) to glass, then attaching the LED chip to the mass transfer adhesive, followed by cleaning, lamination, and reflow, and finally removing the mass transfer adhesive.

Conventional giant transfer adhesives have excessively high release forces (greater than approximately 2 g/cm), which easily leads to adhesive snatching problems. Furthermore, conventional giant transfer adhesives have relatively low heat resistance temperatures, making it easy for adhesive residue to form on the LED chip surface during removal. Additionally, the process of bonding LED chips to the giant transfer adhesive typically requires alignment using 248 nm laser light; however, conventional giant transfer adhesives have low transmittance (less than approximately 90%) for alignment light in the 240 nm to 250 nm (e.g., 248 nm) range, making alignment less favorable.

In view of this, there is an urgent need to provide an adhesive composition and film structure for mass transfer to reduce the release force of the adhesive layer and improve its heat resistance temperature and transmittance to para light in the range of 240 nm to 250 nm.

One aspect of this invention is to provide an adhesive composition for mass transfer, which, through a specific weight ratio of crosslinking agent, anchoring agent and catalyst, reduces the release force of the adhesive layer and increases the heat resistance temperature of the adhesive layer and the transmittance of the adhesive layer to parallax of a specific wavelength.

Another aspect of the invention is to provide a film structure for mass transfer, comprising an adhesive composition for mass transfer as described above as an adhesive layer.

According to one aspect of the present invention, an adhesive composition for mass transfer is provided, comprising silicone resin, a crosslinking agent, an anchoring agent, and a catalyst. The adhesive composition for mass transfer comprises 100 wt%, and the silicone resin comprises 95 wt% to 99 wt%. The weight ratio of the crosslinking agent, anchoring agent, and catalyst is 1:2:4.

According to one embodiment of the present invention, the aforementioned silicone resin comprises a first silicone resin, wherein the silicone-based resin is 100 wt% and the first silicone resin is 67 wt% to 80 wt%; and a second silicone resin, wherein the silicone-based resin is 100 wt% and the second silicone resin is 20 wt% to 33 wt%, and the viscosity of the first silicone resin is greater than that of the second silicone resin.

According to one embodiment of the present invention, the aforementioned silicone resin comprises at least one of polymethylsiloxane, polydimethylsiloxane, and phenyl polytrimethylsiloxane.

According to one embodiment of the present invention, the crosslinking agent comprises methylhydrosiloxane and/or triethoxypolyethylhydrosiloxane.

According to one embodiment of the present invention, the anchoring agent comprises at least one of 2,3-epoxypropylpropyltrimethoxysilane, tetradecyl hexasiloxane and phenylpropylsiloxane.

According to one embodiment of the present invention, the catalyst comprises at least one of an organic platinum compound, an organic bismuth compound, and an organic titanium compound.

According to another aspect of the present invention, a film structure for mass transfer is provided, comprising a first release layer, a second release layer disposed below the first release layer, and an adhesive layer disposed between the first release layer and the second release layer, wherein the adhesive layer comprises the adhesive composition for mass transfer of the above aspect.

According to one embodiment of the present invention, the thickness of the adhesive layer is from 1 μm to 50 μm.

According to one embodiment of the present invention, the release force between the adhesive layer and the first release layer or the second release layer is 0.1 g/cm to 0.5 g/cm.

According to one embodiment of the present invention, the heat resistance temperature of the adhesive layer is greater than 350°C.

By applying the adhesive composition and film structure of the present invention for mass transfer, crosslinking agent, anchoring agent and catalyst in a specific weight ratio can reduce the release force of the adhesive layer and improve its heat resistance temperature and transmittance to parallax of a specific wavelength.

The following disclosure provides numerous different embodiments or illustrations to implement various features of the invention. The specific examples of components and configurations described below are for the purpose of simplifying this disclosure. These are, of course, merely illustrative and are not intended to be limiting. For example, the description of a first feature being formed on or above a second feature includes embodiments where the first and second features are in direct contact, as well as embodiments where other features are formed between the first and second features such that the first and second features are not in direct contact.

Furthermore, spatial relative terms, such as "beneath," "below," "lower," "above," and "upper," are used to easily describe the relationship between parts or features depicted in the drawings and other parts or features. In addition to the directions depicted in the drawings, spatial relative terms also include different orientations of the components during use or operation. The device may be oriented in other ways (rotated 90 degrees or in other directions), and the spatial relative descriptions used in this disclosure can also be interpreted in this way.

As used herein, “around,” “about,” “approximately,” or “substantially” generally mean within 20 percent, 10 percent, or 5 percent of the stated value or range. The numerical values described herein are approximate, meaning that the terms “around,” “about,” “approximately,” or “substantially” can be inferred even if not explicitly stated.

As stated above, the present invention provides an adhesive composition and film structure for mass transfer, which reduces the release force of the adhesive layer and improves its heat resistance temperature and transmittance to parallax of a specific wavelength by using crosslinking agent, anchoring agent and catalyst in a specific weight ratio.

The adhesive composition for mass transfer of the present invention comprises silicone resin, crosslinking agent, anchoring agent, and catalyst. In some embodiments, the adhesive composition for mass transfer is 100 wt%, the silicone resin is about 95 wt% to about 99 wt%, and the total amount of crosslinking agent, anchoring agent, and catalyst is about 1 wt% to about 5 wt%. If the silicone resin content is too low (e.g., less than 95 wt%), the adhesive composition will have too low tack and will not be able to effectively adhere the wafer during mass transfer. Conversely, if the silicone resin content is too high (e.g., greater than 99 wt%), the content of the remaining components will be too low, and the adhesive layer formed by the adhesive composition will not have sufficient light transmittance, and the release force will be too high, thus causing adhesive snatching problems.

In some embodiments, the silicone resin comprises at least one of polymethylsiloxane (CAS NO.: 9004-73-3), polydimethylsiloxane (CAS NO.: 63148-62-9), and phenyl polytrimethylsiloxane (CAS NO.: 2116-84-9). In some embodiments, the silicone resin of the adhesive composition used for mass transfer comprises a first silicone resin and a second silicone resin, wherein the materials of the first silicone resin and the second silicone resin may be the same or different, the first silicone resin being a silicone resin having a higher viscosity (e.g., a viscosity of about 900 g/cm to about 1000 g/cm) and the second silicone resin being a silicone resin having a lower viscosity (e.g., a viscosity of about 0 g/cm to about 1 g/cm). In the aforementioned embodiment, the silicone resin is 100 wt%, the first silicone resin is about 67 wt% to about 80 wt%, and the second silicone resin is about 20 wt% to about 33 wt%. By controlling the content of the first silicone resin and the second silicone resin within the aforementioned range, the adhesive composition can have suitable tackiness.

In some embodiments, the weight ratio of crosslinking agent, anchoring agent, and catalyst is 1:2:4. Since the total content of crosslinking agent, anchoring agent, and catalyst is fixed, the content of the three will affect each other. Their content ratio must be maintained within the aforementioned range in order to ensure that the adhesive layer formed by the adhesive composition has lower release force, better light transmittance, and higher heat resistance temperature. If the anchoring agent and/or catalyst content is too high or the crosslinking agent content is too low, the adhesive layer will have poor penetration of alignment light at a specific wavelength (e.g., 240 nm to 250 nm), which is not conducive to the alignment step during mass transfer. Conversely, if the anchoring agent and/or catalyst content is too low or the crosslinking agent content is too high, the release force of the adhesive layer will be too high and the heat resistance temperature will be low, making it easy for adhesive to be squeezed and for adhesive residue to occur.

In some specific examples, the crosslinking agent may comprise methylhydrosiloxane (CAS NO.: 63148-57-2) and/or triethoxypolyethylhydrosiloxane (CAS NO.: 24979-95-1), the anchoring agent may comprise at least one of 2,3-epoxypropylpropyltrimethoxysilane (CAS NO.: 2530-83-8), tetradecyl hexasiloxane (CAS NO.: 107-52-8), and phenylpropylsiloxane (CAS NO.: 68037-90-1), and the catalyst may comprise an organoplasmium compound (e.g., 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum compound (CAS NO.: 24979-95-1)). 68478-92-2), at least one of an organic bismuth compound and an organic titanium compound.

Please refer to Figure 1, which is a cross-sectional view of a film structure 100 for mass transfer according to some embodiments of the present invention. The film structure 100 includes a first release layer 110A, a second release layer 110B, and an adhesive layer 120, wherein the adhesive layer 120 is disposed between the first release layer 110A and the second release layer 110B. In some embodiments, the thickness of the adhesive layer 120 is from about 1 μm to about 50 μm, while the thicknesses of the first release layer 110A and the second release layer 110B are from about 1 μm to about 1000 μm.

In some embodiments, the line-average roughness (Ra) of the surface center where the adhesive layer 120 contacts the first release layer 110A (or the second release layer 110B) is from about 0.01 μm to about 10 μm. In some embodiments, the haze of the first release layer 110A and the second release layer 110B is from about 0.1% to 100%.

Adhesive layer 120 comprises the aforementioned adhesive composition for mass transfer. In some embodiments, the release force between adhesive layer 120 and the first release layer 110A (or the second release layer 110B) is approximately 0.1 g/cm to approximately 0.5 g/cm. In some embodiments, the initial tack of adhesive layer 120 is approximately 0.5 g/cm to approximately 3 g/cm. It should be noted that the release force is measured by a tensile test according to ASTM D3330 at a temperature of 25°C, while the initial tack is measured using an initial tack tester according to the ASTM D3330 tensile test. Compared to the release force of conventional adhesive layers, which is greater than 2 g/cm, the release force of the adhesive layer of this invention is smaller, thus avoiding the occurrence of adhesive snatching.

In some embodiments, the heat resistance temperature of the adhesive layer 120 is greater than approximately 350°C. It should be noted that the aforementioned "heat resistance temperature" refers to "T _d (5%)" (decomposition temperature at 5% weight loss), representing the temperature at which the adhesive layer decomposes upon heating to a point of 5% initial weight loss, which is evaluated using a thermogravimetric analyzer. Compared to conventional adhesive layers with heat resistance temperatures below 320°C, the adhesive layer 120 of this invention can have a higher heat resistance temperature, thereby preventing adhesive residue from forming on the LED chip surface during subsequent removal of the large amount of transfer film.

In some embodiments, the adhesive layer 120 has a transmittance of greater than approximately 95% for light with wavelengths of 240 nm to 250 nm. It should be noted that the transmittance is measured using a spectrophotometer after the first release layer 110A and the second release layer 110B have been removed. Compared to conventional adhesive layers with transmittance of less than 90% for light with wavelengths of 240 nm to 250 nm, the adhesive layer 120 of this invention has higher transmittance, making LED chip alignment easier during mass transfer processes.

The following examples illustrate the application of the present invention, but they are not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Example 1 and Comparative Examples 1 to 5

The adhesive composition for mass transfer in Examples 1 and Comparative Examples 1 to 5 comprises 99 wt% polymethylsiloxane as a silicone resin, wherein the silicone resin comprises 80 wt% high-viscosity silicone resin (viscosity of 1000 g/cm) and 20 wt% low-viscosity silicone resin (viscosity of 0 g/cm). The adhesive composition also comprises methylhydrosiloxane as a crosslinking agent, 2,3-epoxypropylpropyltrimethoxysilane as an anchoring agent, and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum compound as a catalyst. The total content of the crosslinking agent, anchoring agent, and catalyst is 1 wt%. The only difference between Example 1 and Comparative Examples 1 to 5 is the weight ratio of the crosslinking agent, anchoring agent, and catalyst, as shown in Table 1. Examples 2 and Comparative Examples 6 to 10

Examples 2 and Comparative Examples 6 to 10 are adhesive compositions with similar compositions to Examples 1 and Comparative Examples 1 to 5, respectively. The only difference is that the adhesive compositions of Examples 2 and Comparative Examples 6 to 10 for mass transfer contain 97.5 wt% polymethylsiloxane as the silicone resin, wherein the silicone resin contains 75 wt% high-viscosity silicone resin and 25 wt% low-viscosity silicone resin. The total content of the crosslinker, anchoring agent, and catalyst is 2.5 wt%. The only difference between Example 2 and Comparative Examples 6 to 10 is the weight ratio of the crosslinking agent, anchoring agent, and catalyst, as shown in Table 2. Examples 3 and Comparative Examples 11 to 15

Examples 3 and Comparative Examples 11 to 15 are adhesive compositions with similar compositions to Examples 1 and Comparative Examples 1 to 5, respectively. The only difference is that the adhesive compositions of Examples 3 and Comparative Examples 11 to 15 for mass transfer contain 95 wt% polymethylsiloxane as the silicone resin, wherein the silicone resin contains 67 wt% high-viscosity silicone resin and 33 wt% low-viscosity silicone resin. The total content of the crosslinker, anchoring agent, and catalyst is 5 wt%. The only difference between Example 3 and Comparative Examples 11 to 15 is the weight ratio of the crosslinking agent, anchoring agent, and catalyst, as shown in Table 3. Evaluation Method Adhesive Strength of the Adhesive Layer

The adhesive force of the adhesive layer was measured using an initial tack tester according to ASTM D3330 tensile test. The test results for Examples 1 to 3 and Comparative Examples 1 to 15 are shown in Tables 1 to 3. Release Force of Adhesive Layer and Release Layer (g/cm)

The release force (g/cm) of the adhesive layer and release layer was measured at 25°C using the tensile test specified in ASTM D3330. The test results for Examples 1 to 3 and Comparative Examples 1 to 15 are shown in Tables 1 to 3. Heat Resistance Temperature

The heat resistance temperature was determined using a thermogravimetric analyzer (TGA, brand: TA, model: Q-500) by analyzing the adhesive composition under nitrogen ( _N2 ) atmosphere as it was heated from room temperature (25°C) to 500°C at a heating rate of 20°C per minute. The thermal decomposition temperature at which a weight loss of 5% was reached was defined as the heat resistance temperature of the temporary adhesive composition. The test results for Examples 1 to 3 and Comparative Examples 1 to 15 are shown in Tables 1 to 3. Penetration

The transmittance of the adhesive composition to light with wavelengths from 240 nm to 250 nm was measured using a spectrophotometer (UV/Vis Spectrophotometer; manufacturer: HITACHI, model: U-4100) at a scanning rate of 600 nm per minute. The detection results of Examples 1 to 3 and Comparative Examples 1 to 15 are shown in Tables 1 to 3.

Table 1 Implementation Example 1 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 High viscosity silicone resin (%) 80 80 80 80 80 80 Low viscosity silicone resin (%) 20 20 20 20 20 20 Crosslinking agent: Anchoring agent: Catalyst 1:2:4 1:1:1 1:2:2 1:2:3 1:2:4.5 1:2:5 Adhesive layer adhesion force (g/cm) 3 3 3 3 3 3 Release force (g/cm) between adhesive layer and release layer 0.1 2.5 1.8 0.9 0.1 0.1 Heat resistance temperature (°C) 353 310 322 335 353 355 Penetration (%) @ 240 nm ~ 250 nm 95.8 99.8 99 98.5 91.9 86.5

Table 2 Implementation Example 2 Comparative example 6 Comparative example 7 Comparative example 8 Comparative example 9 Comparative example 10 High viscosity silicone resin (%) 75 75 75 75 75 75 Low viscosity silicone resin (%) 25 25 25 25 25 25 Crosslinking agent: Anchoring agent: Catalyst 1:2:4 1:1:1 1:2:2 1:2:3 1:2:4.5 1:2:5 Adhesive layer adhesion force (g/cm) 2 2 2 2 2 2 Release force (g/cm) between adhesive layer and release layer 0.3 2.6 1.6 1.1 0.1 0.1 Heat resistance temperature (°C) 357 305 327 333 356 359 Penetration (%) @ 240 nm ~ 250 nm 96.2 99.2 98.8 98.1 92.1 88.5

Table 3 Implementation Example 3 Comparative example 11 Comparative example 12 Comparative example 13 Comparative example 14 Comparative example 15 High viscosity silicone resin (%) 67 67 67 67 67 67 Low viscosity silicone resin (%) 33 33 33 33 33 33 Crosslinking agent: Anchoring agent: Catalyst 1:2:4 1:1:1 1:2:2 1:2:3 1:2:4.5 1:2:5 Adhesive layer adhesion force (g/cm) 0.5 0.5 0.5 0.5 0.5 0.5 Release force (g/cm) between adhesive layer and release layer 0.5 3 2 1.3 0.1 0.1 Heat resistance temperature (°C) 362 308 319 338 359 352 Penetration (%) @ 240 nm ~ 250 nm 95.9 98.8 98.4 97.8 91.2 86.2

According to Tables 1 to 3 above, when the difference in content between the catalyst and the crosslinker is not significant (e.g., Comparative Examples 1 to 3, Comparative Examples 6 to 8, and Comparative Examples 11 to 13), because the total content of crosslinker, anchoring agent, and catalyst is fixed, the relative content of the catalyst is too low to increase the reaction rate between the silicone resin and the crosslinker. This will lead to a decrease in the reaction rate between the silicone resin and the crosslinker. Insufficient crosslinking between crosslinkers results in a high degree of flexibility in the formed adhesive layer, which in turn increases the adhesion to the release layer. Consequently, the release force between the adhesive layer and the release layer in the resulting film structure is too large, and the heat resistance temperature is low. Conversely, when the relative content of catalyst is too high, the metal particles of the catalyst will affect the light transmittance, resulting in a lower transmittance of the adhesive layer to light with wavelengths of 240 nm to 250 nm. Only when the weight ratio of crosslinker, anchoring agent and catalyst is 1:2:4 can the resulting adhesive layer have both low release force, high heat resistance temperature and high transmittance to light with wavelengths of 240 nm to 250 nm, and also have appropriate adhesive layer adhesion.

According to the above embodiments, the adhesive composition for mass transfer and the adhesive film structure for mass transfer of the present invention, the adhesive composition for mass transfer, by means of a specific weight ratio of crosslinking agent, anchoring agent and catalyst, can reduce the release force of the resulting adhesive layer and release layer, and improve the heat resistance temperature of the adhesive layer and the transmittance of the alignment light to a specific wavelength.

Although the present invention has been disclosed above with several embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the art to which the present invention pertains may make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended patent application.

100: Adhesive film structure 110A: First release layer 110B: Second release layer 120: Adhesive layer

A better understanding of the features disclosed herein will be achieved by referring to the following detailed description and accompanying figures. It should be noted that, as is standard practice in the industry, many features are not drawn to scale. In fact, the dimensions of many features can be arbitrarily scaled for clarity of discussion. [Figure 1] is a cross-sectional view illustrating a mass transfer film structure according to some embodiments of the present invention.

Domestic Storage Information (Please record in order of storage institution, date, and number) None International Storage Information (Please record in order of storage country, institution, date, and number) None

100: Film Structure

110A: First release layer

110B: Second release layer

120: Adhesive layer

Claims (9)

An adhesive composition for mass transfer comprises: a silicone resin, wherein the adhesive composition for mass transfer is 100 wt%, the silicone resin is 95 wt% to 99 wt%, the silicone resin comprises a first silicone resin and a second silicone resin, the first silicone resin having a greater tack than the second silicone resin, and based on the silicone resin being 100 wt%, the first silicone resin being 67 wt% to 80 wt%, and the second silicone resin being 20 wt% to 33 wt%. wt%; a crosslinking agent; an anchoring agent; and a catalyst, wherein the weight ratio of the crosslinking agent, the anchoring agent, and the catalyst is 1:2:4. The adhesive composition for mass transfer as described in claim 1, wherein the silicone resin comprises at least one of polymethylsiloxane, polydimethylsiloxane, and phenyl polytrimethylsiloxane. The adhesive composition for mass transfer as described in claim 1, wherein the crosslinking agent comprises methylhydrosiloxane and/or triethoxypolyethylhydrosiloxane. The adhesive composition for mass transfer as described in claim 1, wherein the anchoring agent comprises at least one of 2,3-epoxypropylpropyltrimethoxysilane, tetradecyl hexasiloxane, and phenylpropylsiloxane. The adhesive composition for mass transfer as described in claim 1, wherein the catalyst comprises at least one of an organoplasm compound, an organobenzide compound, and an organotitanium compound. A film structure for mass transfer includes: a first release layer; a second release layer disposed below the first release layer; and an adhesive layer disposed between the first release layer and the second release layer, wherein the adhesive layer comprises an adhesive composition for mass transfer as described in any one of claims 1 to 5. The adhesive film structure for mass transfer as described in claim 6, wherein the thickness of the adhesive layer is from 1 μm to 50 μm. The adhesive film structure for mass transfer as described in claim 6, wherein the release force between the adhesive layer and the first release layer or the second release layer is from 0.1 g/cm to 0.5 g/cm. The adhesive film structure for mass transfer as described in claim 6, wherein the heat resistance temperature of the adhesive layer is greater than 350°C.