A fabric-based high resolution flexible circuit board and its directed printing method and applications

Abstract

The application relates to a fabric-based high-resolution flexible circuit board and a directional printing method and application thereof. The application belongs to the field of wearable electronics and preparation thereof. The application aims to solve the technical problems that the preparation process of most flexible circuits still adopts coating or printing, it is difficult to meet the needs of small wearable electronic products, and the flexible electronic devices composed of an electronic functional layer and a fabric substrate are not matched in interlayer Young's modulus, and the phenomenon of fracture and even interface separation is prone to occur in long-term use. The application provides a directional printing technology of a fabric-based high-resolution flexible circuit, and the obtained flexible circuit has good mechanical properties. The printed circuit with the fabric as the substrate can be bent and curved to adapt to human movement, and has certain mechanical flexibility and stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wearable electronics and its preparation, and particularly relates to a fabric-based high-resolution flexible circuit board and a directional printing method and application thereof. BACKGROUND

[0002] With the increasing demand for intelligent wearable products, future intelligent wearable devices will inevitably develop in the direction of small size, low cost, customization and environmental protection. Among them, the flexible circuit not only efficiently conducts various electronic elements, but also meets the characteristics of lightness and flexibility, which is the research focus of current scientific researchers related to intelligent wearable products.

[0003] At present, there are few types of substrate materials and conductive materials for flexible circuits, and the process of manufacturing flexible circuits also has deficiencies. The traditional flexible circuit is composed of conductive materials such as metal nanoparticles, metal oxides and conductive polymers and flexible substrates such as paper, plastic and silica gel. Such flexible circuits usually have high elasticity and wear resistance, but poor air permeability and bending resistance. At the same time, traditional single conductive materials are increasingly difficult to meet people's pursuit of high performance in actual application.

[0004] At present, the preparation process of most flexible circuits still adopts coating or printing, which is difficult to meet the needs of small wearable electronic products. In addition, the flexible electronic device composed of the composite between the electronic functional layer and the fabric substrate has the problem of mismatching of interlayer Young's modulus, which is prone to fracture and even interfacial separation in long-term use. Therefore, it is urgent to develop a fabric-based high-resolution flexible circuit with high precision, high fineness, high ideal flexibility and air permeability. SUMMARY

[0005] To solve the above technical problems, the present application provides the following technical solutions: a fabric-based high-resolution flexible circuit board and a directional printing method and application thereof.

[0006] One of the purposes of the present application is to provide a fabric-based high-resolution flexible circuit board directional printing method, which comprises,

[0007] Step 1: preparing a TiO2 coating layer on the fabric substrate to obtain a flexible coating substrate;

[0008] Step 2: covering a metal mask with a hollow structure consistent with the arrangement of the circuit on the surface of the flexible coating substrate, then irradiating with a low-pressure ultraviolet lamp, then performing alkali washing, and drying to obtain a flexible circuit substrate;

[0009] Step 3: coating a composite nanometer ink on the surface of the flexible circuit substrate, then rolling with a roller to obtain a composite nanometer ink structure self-assembled on the surface of the arrangement of the circuit to obtain a flexible circuit board precursor;

[0010] Step 4: coating the encapsulation layer on the surface of the flexible circuit board precursor to obtain the fabric-based high-resolution flexible circuit board.

[0011] As a preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the fabric in S1 comprises polyester and cotton.

[0012] As a preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the thickness of the TiO2 coating layer in S1 is 10-500 μm.

[0013] As a preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the low-pressure parallel ultraviolet lamp in S2 irradiates the substrate in parallel.

[0014] As a preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the wavelength of the light of the low-pressure parallel ultraviolet lamp in S2 is 100-400 nm.

[0015] As a preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the solution used for the alkali washing in S2 is NaOH or KOH.

[0016] As a preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the composite nano ink in S3 is silver nanoparticle / carbon nanotube composite ink.

[0017] As a further preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the content of the silver nanoparticles in the composite nano ink is 10-30 wt%, and the content of the carbon nanotubes is 10-30 wt%.

[0018] As a preferred scheme of the fabric-based high-resolution flexible circuit board directional printing method of the present application, the encapsulation layer in S4 is poly-p-xylylene.

[0019] The second object of the present application is to provide a fabric-based high-resolution flexible circuit board prepared by the above method.

[0020] The third object of the present application is to provide an application of the fabric-based high-resolution flexible circuit board prepared by the above method in the preparation of intelligent wearable products.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The application provides a kind of fabric-based high-resolution flexible circuit directional printing technology, and the obtained flexible circuit has good mechanical properties.The fabric-based printed circuit can adapt to human motion and be bent and curved, and has certain mechanical flexibility and stability.The specific advantages are as follows:

[0023] 1) The flexible circuit prepared by the application has good mechanical properties.The fabric-based printed circuit can adapt to human motion and be bent and curved, and has certain mechanical flexibility and stability.

[0024] 2) The water-based conductive ink material used in the application is easy to handle, purify and recycle, avoiding environmental pollution and resource waste.Meanwhile, the excellent performance of metal materials and carbon nanomaterials is combined.Nano-silver has high conductivity, low melting point, excellent welding quality and reliability.Carbon nanotubes as the second phase of conductive filler improve conductivity and stability, and reduce cost.The obtained flexible circuit has good conductivity.

[0025] 3) The application uses parylene as the packaging layer, and the packaged circuit can be placed in air for a long time after packaging, and has the functions of oxidation resistance, corrosion resistance and anti-displacement, and is suitable for more complex environments and has good stability.

[0026] 4) The application introduces anatase TiO2 coating, and simultaneously uses a low-pressure ultraviolet lamp for parallel irradiation to generate electron-hole pairs.The electrons react with Ti 4+ to become Ti 3+ , and the holes react with oxygen ions on the surface of the film to form oxygen vacancies.Water molecules are adsorbed on the oxygen vacancies and dissociate into hydroxyl groups.The hydroxyl groups further form hydrogen bonds with water molecules, making the film super-hydrophilic.

[0027] 5) The application controls the surface energy intensity of the fabric substrate surface to realize self-driven assembly of the composite nanometer ink on the fabric surface, thereby realizing high-resolution large-area circuit patterns.The printing process has the advantages of easy operation, low equipment requirement, and large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a flowchart of the fabric-based high-resolution flexible circuit directional printing method of the application;

[0029] Among them, 1 is a flexible coating substrate, 2 is a metal mask, 21 is a hollow structure, 3 is a composite nanometer ink, 4 is a roller, and 5 is a packaging layer.

[0030] Figure 2 It is a surface morphology SEM image of the flexible coating substrate obtained in step 1 of Example 1.

[0031] Figure 3Figure 1 is a graph of fabric-based high-resolution flexible circuit board wettability versus NaCl solution soak time for Example 1;

[0032] Figure 4 Figure 4 is a graph of wettability on a flexible circuit substrate obtained from Example 1, Step 2, after UV irradiation.

[0033] Figure 5 Figure 5 is a graph of wettability on a flexible circuit substrate obtained from Example 1, Step 2, without UV irradiation. DETAILED DESCRIPTION

[0034] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference made to the embodiments of the present application.

[0035] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in other manners different from those described herein, and it is understood that persons skilled in the art can make similar generalizations without departing from the scope of the present application, and therefore the present application is not limited to the specific embodiments disclosed below.

[0036] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. The "in one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent or alternative to other embodiments.

[0037] Example 1, in combination Figure 1 The fabric-based high-resolution flexible circuit board directional printing method of the present embodiment comprises the following steps:

[0038] Step 1: A TiO2 coating with a thickness of 10 μm is prepared on a polyester fabric substrate to obtain a flexible coating substrate 1;

[0039] Step 2: A metal mask 2 is covered on the surface of the flexible coating substrate 1, the metal mask 2 is made of stainless steel aluminum, and the metal mask 2 has a hollow structure 21 that matches the arrangement of the circuit, then parallel irradiation is performed using a low-pressure ultraviolet lamp, a low-pressure double-wavelength ultraviolet lamp with a light wavelength of 185 nm and 254 nm is used, the power is 9 W, the light irradiation time is 15 minutes, then alkali washing is performed using a NaOH solution with a concentration of 2.0 wt%, and after drying at 25°C, a flexible circuit substrate is obtained.

[0040] Step 3: coating the composite nano-ink 3 on the surface of the flexible circuit substrate, the composite nano-ink 3 being a silver nanoparticle / carbon nanotube composite ink, wherein the content of silver nanoparticles in the composite nano-ink 3 is 20wt%, and the content of carbon nanotubes is 10wt%, and then rolling with a roller 4 to obtain a self-assembled composite nano-ink structure on the surface of the arranged circuit, thereby obtaining a flexible circuit board precursor;

[0041] Step 4: coating poly-p-xylylene on the surface of the flexible circuit board precursor to form an encapsulation layer 5, thereby obtaining a fabric-based high-resolution flexible circuit board.

[0042] Detection test

[0043] (I) Mechanical property test

[0044] The tensile properties of the flexible coating substrate obtained in Step 1 of Example 1 were tested, and the results are shown in Tables 1-2. As shown in Tables 1-2, the treated polyester fabric has a warp strength of 781.1 N / cm and a weft strength of 449.1 N / cm, which has a relatively high strength and does not change significantly compared with the untreated polyester fabric. It can be seen that TiO2 treatment does not affect the mechanical properties of the fabric.

[0045] Table 1 Warp results

[0046]

[0047] Table 2 Weft results

[0048]

[0049]

[0050] (II) Surface morphology

[0051] Figure 2 The surface morphology SEM image of the flexible coating substrate obtained in Step 1 of Example 1 is shown in the figure. It can be seen that a large amount of TiO2 is uniformly attached to the surface of the fabric.

[0052] (III) TiO2 loading

[0053] As shown in Table 3.

[0054] Table 3 TiO2 loading

[0055]

[0056] (IV) Bending stability test

[0057] 1. Printed circuit 1 Ω / cm

[0058] 2. Bending test

[0059] The sample treated in step 3 of Example 1 was bent, and the conductivity of the fabric was measured after one cycle to evaluate the stability of the fabric's conductivity. The test results are shown in Table 4. After 2000 bends, the resistance value was 1.1 Ω / cm, indicating good bending stability.

[0060] Table 4 Results of Bending Stability Test

[0061]

[0062] (V) Acid Resistance Test

[0063] Table 5 shows the relationship between the soaking time and wettability of the sample in Example 1 under acidic conditions of pH=1. It can be seen that the hydrophobicity deteriorates over time. As the soaking time increases, the hydrophobicity of the sample gradually decreases, but the decrease is not significant, indicating that the product of the present invention has good acid resistance.

[0064] Table 5

[0065]

[0066] (vi) Perspiration resistance test

[0067] Figure 3 The relationship between immersion time and wettability of the sample in NaCl (3.5 wt%) solution in Example 1 is shown. It can be seen that the hydrophobic angle of the sample decreases by approximately 6° every 24 hours in NaCl solution. The change tends to stabilize after immersion for 144 hours. This demonstrates that the sample has a certain degree of NaCl resistance.

[0068] (vii) Hydrophilicity and hydrophobicity test

[0069] The contact angle of the flexible circuit board obtained in step 2 of Example 1 was tested, and the difference in hydrophilicity between the irradiated and unirradiated portions was as follows: Figures 4-5 As shown, the hydrophobic angle of the sample treated with nano-TiO2 and then irradiated is 25°, indicating good hydrophilicity. The hydrophobic angle of the unirradiated part is 135°, indicating poor hydrophilicity. It can be seen that irradiation treatment can significantly improve the wettability of polyester fabric.

[0070] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for directional printing of high-resolution flexible circuit boards on a fabric substrate, characterized in that, The method includes, Step 1: Prepare a TiO2 coating on a fabric substrate to obtain a flexible coating substrate; the fabric includes polyester and cotton, and the thickness of the TiO2 coating is 10-500 μm; Step 2: Cover the surface of the flexible coating substrate with a metal mask having a hollow structure that matches the circuit layout, then irradiate it with a low-pressure ultraviolet lamp, followed by alkaline washing and drying to obtain a flexible circuit board; the low-pressure ultraviolet lamp is parallel to the substrate; the wavelength of the low-pressure parallel ultraviolet lamp is 100-400 nm; the alkaline washing solution is NaOH or KOH. Step 3: Coat the surface of the flexible circuit board with composite nano-ink, and then roll it using a roller to obtain a self-assembled composite nano-ink structure on the surface of the arranged lines, thus obtaining the precursor of the flexible circuit board; the composite nano-ink is a silver nanoparticle / carbon nanotube composite ink; the content of silver nanoparticles in the composite nano-ink is 10-30 wt%, and the content of carbon nanotubes is 10-30 wt%; Step 4: Coat the surface of the flexible circuit board precursor with an encapsulation layer, which is parylene, to obtain a fabric-based high-resolution flexible circuit board.

2. The method for directional printing of high-resolution flexible circuit boards on a fabric substrate according to claim 1, characterized in that, Includes the following steps: Step 1: Prepare a TiO2 coating with a thickness of 10 μm on a polyester fabric substrate to obtain a flexible coating substrate; Step 2: A metal mask is placed on the surface of the flexible coating substrate. The metal mask is made of stainless steel or aluminum and has a hollow structure that matches the circuit layout. Then, a low-pressure ultraviolet lamp is used for parallel irradiation. The lamp has a wavelength of 185nm and 254nm and a power of 9W. The irradiation time is 15 minutes. Then, the substrate is washed with a 2.0 wt% NaOH solution and dried at 25°C to obtain the flexible circuit board. Step 3: Coat the surface of the flexible circuit board with composite nano-ink, wherein the composite nano-ink is a silver nanoparticle / carbon nanotube composite ink, wherein the silver nanoparticle content in the composite nano-ink is 20wt% and the carbon nanotube content is 10wt%. Then roll the composite nano-ink structure on the surface of the circuit arrangement by roller pressing to obtain the flexible circuit board precursor. Step 4: Coat the surface of the flexible circuit board precursor with parylene to form an encapsulation layer, thereby obtaining a fabric-based high-resolution flexible circuit board.

3. The fabric-based high-resolution flexible circuit board prepared by the method of any one of claims 1-2.

4. The application of the fabric-based high-resolution flexible circuit board prepared by the method of any one of claims 1-2 in the preparation of smart wearable products.

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