KR-20260065454-A - Conductive thin film applicable to free-form surfaces using laser sintering and its manufacturing method

Abstract

A conductive thin film applicable to a freeform surface using laser sintering according to the present invention is a conductive thin film sintered by irradiating a laser beam onto a photocurable composite layer comprising metal nanoparticles and a photocurable polymer, wherein the conductive thin film is sintered only to a predetermined depth from the surface of the photocurable composite layer in a shape corresponding to the pattern of irradiating the laser beam and can be separated from the photocurable composite.

Inventors

• 이길용
• 최승현
• 이민형
• 박지수

Assignees

• 국립금오공과대학교 산학협력단

Dates

Publication Date

20260508

Application Date

20241227

Priority Date

20241101

Claims (9)

1. A conductive thin film sintered by irradiating a laser beam onto a photocurable composite layer comprising metal nanoparticles and a photocurable polymer, The conductive thin film is a conductive thin film applicable to a freeform surface using laser sintering, which is sintered only to a predetermined depth from the surface of the photocurable composite layer in a shape corresponding to the pattern of irradiating the laser beam and separated from the photocurable composite.
2. In paragraph 1, A conductive thin film applicable to a freeform surface using laser sintering, wherein the metal nanoparticles are silver nanoparticles, and the photocurable composite layer comprises 100 to 200 parts by weight of the silver nanoparticles per 100 parts by weight of the photocurable polymer.
3. In paragraph 1, A conductive thin film applicable to a freeform surface using laser sintering, wherein the scan interval of the laser beam is 50 to 70 μm.
4. In paragraph 1, A conductive thin film applicable to a freeform surface using laser sintering, wherein as the energy density of the laser beam increases from 54.57 J/cm² to 229.18 J/cm², the resistivity of the conductive thin film sintered by irradiating the laser beam decreases from 4.72× 10⁻⁶ Ω·m to 1.52× 10⁻⁶ Ω·m and the thickness of the conductive thin film increases from 19.24 μm to 64.13 μm.
5. In paragraph 1, A conductive thin film applicable to a freeform surface using laser sintering, wherein as the energy density of the laser beam increases from 76.39 J/cm² to 178.25 J/cm², the stiffness of the sintered conductive thin film increases from 0.06 N/mm² to 0.21 N/mm², and the resistance change rate (ΔR/R) of the conductive thin film decreases from 0.0724 to 0.0358 at a bending displacement of 1.5 mm.
6. A step of mixing metal nanoparticles and a photocurable polymer to form a photocurable composite layer; A step of irradiating a laser beam onto a photocurable composite layer to form a conductive thin film sintered only to a predetermined depth from the surface of the photocurable composite layer in a shape corresponding to the pattern of irradiating the laser beam; and A method for manufacturing a conductive thin film applicable to a freeform surface using laser sintering, comprising the step of separating the conductive thin film from the photocurable composite material.
7. In paragraph 6, A method for manufacturing a conductive thin film applicable to a freeform surface using laser sintering, wherein the resistivity of the sintered conductive thin film decreases as the energy density of the laser beam increases.
8. In paragraph 6, A method for manufacturing a conductive thin film applicable to a freeform surface using laser sintering, wherein the thickness of the sintered conductive thin film increases as the energy density of the laser beam increases.
9. In paragraph 6, A method for manufacturing a conductive thin film applicable to a freeform surface using laser sintering, wherein the stiffness of the sintered conductive thin film increases and the resistance change rate (ΔR/R) decreases as the energy density of the laser beam increases.

Description

Conductive thin film applicable to free-form surfaces using laser sintering and its manufacturing method The present invention relates to a conductive thin film that can be applied to a freeform surface by forming the conductive thin film on a photocurable composite without a substrate by irradiating it with a laser and then separating it, and a method for manufacturing the same. Process research on conductive patterns is actively being conducted today for application in the fabrication of various devices, such as flexible or foldable devices. Among these processes, laser sintering is widely used because it allows for the relatively rapid and easy production of conductive patterns. Furthermore, it is known to be easy to apply to direct printing and to possess high reproducibility. In order to apply a conductive pattern through laser sintering to a common curved surface such as a mobile phone, mini drone, handle, LED light, medical examination device, or sensor, it is necessary to manufacture an injection-molded product including a curved surface and, for each product, sinter it by irradiating a laser with a stabilized output using a 3D scanner onto the three-dimensional curved surface. In addition, as the market for wearable devices such as glasses, watches, and clothing, as well as stretchable and foldable devices, grows, there is increasing demand for conductive patterns that can be applied to freeform surfaces. However, there is a problem in that it is more difficult to apply conductive patterns to freeform surfaces than to ordinary curved surfaces. Therefore, research is needed on a conductive thin film applicable to freeform surfaces using laser sintering to solve the aforementioned problem, and a method for manufacturing the same. FIG. 1 is a conceptual diagram of a method for fabricating a conductive thin film using laser sintering according to one embodiment of the present invention. FIG. 2 is a conceptual diagram of a method for fabricating a conductive thin film by laser continuous scanning according to one embodiment of the present invention. FIG. 3 is a conceptual diagram of a method for fabricating a conductive thin film using laser digital scanning according to one embodiment of the present invention. FIG. 4 is a schematic diagram of a conductive thin film fabrication apparatus using laser sintering according to one embodiment of the present invention. Figure 5 is a graph of thickness and resistivity according to energy density of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. Figure 6 is a resistance graph according to the material mixing ratio and scan interval of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. Figure 7 is an image of the microstructure of a conductive thin film according to the energy density of a laser beam according to one embodiment of the present invention. Figure 8 is a photograph showing the microstructure and thickness of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention as a function of the energy density of the laser beam. FIG. 9 is a conceptual diagram of an apparatus for evaluating the mechanical properties of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. FIG. 10 is a conceptual diagram of a method for evaluating the mechanical properties of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. FIG. 11 is a conceptual diagram of the measurement of the resistance change rate (Δ??/??) during the bending test of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. Figure 12 is the result of a bending test for evaluating the mechanical properties of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. FIG. 13 is a photograph of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. FIG. 14 is a photograph of a conductive thin film fabricated using laser sintering according to one embodiment of the present invention. Specific embodiments of the present invention will be described in detail below with reference to the drawings. However, the concept of the present invention is not limited to the presented embodiments. Those skilled in the art who understand the concept of the present invention may easily propose other inventions that are inferior or other embodiments included within the scope of the concept of the present invention by adding, changing, or deleting other components within the same scope of the concept, and such are also to be considered to be included within the scope of the concept of the present invention. Additionally, components with the same function within the scope of the same concep