阅读说明：本技术 灵活定制高可调柔性微加热器的复合加工方法及微加热器 (Composite processing method for flexibly customizing high-adjustable flexible micro-heater and micro-heater ) 是由 杨晔 于 2021-07-29 设计创作，主要内容包括：本发明涉及一种灵活定制高可调柔性微加热器的复合加工方法及微加热器,制备方法包括：S1：以激光直写的方式对柔性基底表面进行直写刻蚀加工,获得图案化的激光诱导石墨烯结构,作为加热图案区域；S2：装夹三维绝缘掩膜版,并以选择性电化学沉积材料在加热图案区域上进行电化学沉积,得到电极和互联导体图案；S3：以封装柔性聚合物作为封装层,完成柔性微加热器的制造。与现有技术相比,本发明加工工艺过程操作方便、绿色环保、加工精度高、成本低,对柔性微加热器件的开发和加工具有重要的应用价值；加工的柔性微加热器能够广泛地用于生物医疗、可穿戴式电子设备、实验室研究、智能电子器件以及软机器人等各种领域。(The invention relates to a composite processing method for flexibly customizing a high-adjustable flexible micro-heater and the micro-heater, wherein the preparation method comprises the following steps: s1: performing direct-writing etching processing on the surface of the flexible substrate in a laser direct-writing mode to obtain a patterned laser-induced graphene structure serving as a heating pattern area; s2: clamping a three-dimensional insulating mask, and carrying out electrochemical deposition on the heating pattern area by using a selective electrochemical deposition material to obtain an electrode and an interconnection conductor pattern; s3: and (4) taking the packaging flexible polymer as a packaging layer to finish the manufacture of the flexible micro-heater. Compared with the prior art, the processing technology has the advantages of convenient operation, environmental protection, high processing precision and low cost, and has important application value for the development and processing of flexible micro-heating devices; the processed flexible micro-heater can be widely applied to various fields such as biological medicine, wearable electronic equipment, laboratory research, intelligent electronic devices, soft robots and the like.)

1. A composite processing method for flexibly customizing a high-adjustable flexible micro-heater is characterized by comprising the following steps:

s1: performing direct-writing etching processing on the surface of the flexible substrate in a laser direct-writing mode to obtain a patterned laser-induced graphene structure serving as a heating pattern area;

s2: clamping a three-dimensional insulating mask, and carrying out electrochemical deposition on the heating pattern area by using a selective electrochemical deposition material to obtain an electrode and an interconnection conductor pattern;

s3: and (4) taking the packaging flexible polymer as a packaging layer to finish the manufacture of the flexible micro-heater.

2. The composite processing method of the flexible customized high adjustable flexible micro-heater as claimed in claim 1, wherein in S1, the flexible polyimide film is used as a precursor, and the laser direct writing etching is used to etch the predetermined pattern on the surface of the polyimide film.

3. The composite processing method of the flexible customized high adjustable flexible micro-heater according to claim 1, wherein the conductivity of the graphene material generated by laser induction in S1 is adjusted by setting different laser processing parameters, wherein the laser direct write etching processing parameters include laser intensity, scanning speed, and the number of scanning paths.

4. The composite processing method for flexibly customizing the high adjustable flexible micro-heater according to claim 1, wherein the three-dimensional insulating mask is processed by means of photocuring 3D printing in S2.

5. The composite processing method for flexibly customizing the highly tunable and flexible micro-heater according to claim 1, wherein the bottom pattern of the three-dimensional insulating mask in S2 covers a non-deposition surface in an electrochemical deposition process.

6. The composite processing method of claim 1, wherein the three-dimensional insulating mask is provided with a three-dimensional flow channel structure in S2, so that during the selective electrochemical deposition process, the electrolyte can flow and circulate through the three-dimensional flow channel structure, thereby realizing the deposition processing of metal ions on the surface to be processed in the heating pattern area.

7. The composite processing method of the flexible customized high adjustable flexible micro-heater according to claim 1, wherein in S2, the three-dimensional insulation mask is covered on the surface to be processed and fixed by a clamp, the surface to be processed of the heating pattern area is connected with the negative pole of the power supply, and the positive pole of the power supply is connected with the copper sheet or the copper rod.

8. The composite processing method of the flexibly customized highly adjustable flexible micro-heater as claimed in claim 1, wherein the distance between the positive and negative electrodes in S2 is 3-8 cm, and during the selective electrochemical deposition process, the power supply applies dc or pulse voltage to deposit the metal ions in the electrolyte on the surface to be processed which is not covered by the bottom of the mask.

9. The composite processing method of claim 1, wherein the heating performance and flexibility of the flexible micro-heater are adjusted by the conductivity design of the graphene material and the geometric dimension design of the graphene pattern in S2.

10. A flexible microheater according to any of claims 1 to 9 comprising a flexible polyimide film substrate, graphene heating pattern regions, electrodes and interconnecting conductors and an encapsulation layer.

Technical Field

The invention relates to the field of flexible micro heaters, in particular to a composite processing method for flexibly customizing a high-adjustable flexible micro heater.

Background

In recent years, flexible micro-heaters have received considerable attention and can be used in various fields where space is limited, providing controllable thermal stimulation over a series of tiny areas, such as portable biomedical devices, laboratory research, wearable electronics, soft robotics, and the military field, among others. Compare in traditional rigidity electron device, flexible wearable electron device has soft mechanical flexibility, can adapt to different operational environment, satisfies the human deformation requirement to equipment. The method provides new challenges and requirements for manufacturing materials and processing and preparation processes of electronic devices, and has certain mechanical flexibility (such as bending property, stretchability and the like) on the basis of ensuring the electrical properties of the electronic devices.

Flexible microheaters capable of applying thermal stimuli in a small range are of great interest in applications such as wearable electronics, portable medical devices and other space-limited heating devices. The flexible heater is classified into various types including a silica gel heater, a polyimide film heater, a heating tape, a string heater, and the like. And the heating area of the flexible micro-heater is in a micro scale, so that higher requirements are further put forward on the scale and the precision of processing. Currently, the commonly used flexible micro-heaters can be mainly divided into two categories: flexible micro-heaters based on wire-based (wire-based) type and metal foil-based (foil-based) pattern type.

The flexible micro-heater based on the wire type utilizes a conductive metal wire as a heating function unit, and the conventional micro-nano processing technologies such as photoetching, soft photoetching, magnetron sputtering, sacrificial layer stripping and the like are commonly used at present, so that the processing precision of the micro-nano scale can be obtained, but the processing equipment has high cost and complex processing steps, and the flexible micro-heater is not suitable for large-scale production. In addition, heat transfer of wire-based flexible micro-heaters is often limited by wire diameter, poor thermal contact between the wire and the substrate, and the like, resulting in loss of thermal efficiency.

Compared to a wire-type flexible micro-heater, a flexible micro-heater based on a metal foil pattern has a higher flexibility in designing a specific heating area pattern and a better thermal contact between an electrode pattern and a contact object. The main processing methods of the flexible micro-heater are etched metal foil technology, screen printing, photoetching, wet etching and the like, wherein the etched metal foil and the screen printing technology have the advantages of low cost and large-scale production. However, the metal foil type flexible micro-heater relies on the electrode pattern to provide the heating region, and the spiral, honeycomb, S-shaped, fan-shaped and other continuous complex path patterns are commonly used because the electrical conductivity of the metal foil (such as copper foil, aluminum foil, etc.) material is high, so that a longer pattern path is required to provide the micro-heater with a proper resistance value, and a stable and uniform heating region is obtained. This makes the pattern design of the micro-heater more complicated, and the flexibility, precision and performance are limited.

In order to improve the performance of the flexible micro-heater, the development of various novel heating materials and preparation processes become the key and difficult point of the research in the field of the current flexible electronic devices. Various types of materials have been used as the heating element functional material, including various types of metallic materials, such as copper, aluminum, silver, gold, platinum, etc., and electrically conductive non-metallic materials, such as carbon nanotubes, graphene, etc., have been widely used to form flexible micro-heaters.

At present, the preparation and processing method of the flexible micro-heater is still based on the traditional micro-nano processing technology, for example: the micro-nano processing methods can realize high-precision processing, but the processing equipment has high cost and complex operation process, and cannot be used for the production of large-scale devices. The metal foil etching and screen printing process can realize low-cost and large-scale device production, but the processing precision is difficult to reach the micro-nano scale.

Disclosure of Invention

The invention aims to overcome the defects of the existing flexible micro-heater processing and preparing process, provides a novel composite processing and preparing method which is low in cost, high in precision, flexible and controllable in process operation and can realize large-scale customized manufacturing of a light and thin flexible micro-heater with high heating localization.

A first object of the present invention is to protect a composite processing method for flexibly customizing a highly tunable flexible micro-heater, comprising the steps of:

s1: performing direct-writing etching processing on the surface of the flexible substrate in a laser direct-writing mode to obtain a patterned laser-induced graphene structure serving as a heating pattern area;

s2: clamping a three-dimensional insulating mask, and carrying out electrochemical deposition on the heating pattern area by using a selective electrochemical deposition material to obtain an electrode and an interconnection conductor pattern;

s3: and (4) taking the packaging flexible polymer as a packaging layer to finish the manufacture of the flexible micro-heater.

Further, in S1, a flexible polyimide film is used as a precursor, and a predetermined pattern is directly etched on the surface of the polyimide film by using laser.

Further, in S1, the conductivity of the graphene material generated by laser induction is adjusted by setting different laser processing parameters, where the laser direct write etching processing parameters include laser intensity, scanning speed, and the number of times of scanning a path.

Further, the three-dimensional insulating mask in S2 is processed by means of photocuring 3D printing.

Further, the bottom pattern of the three-dimensional insulation mask in S2 covers a non-deposition surface in the electrochemical deposition process.

Further, a three-dimensional flow channel structure is arranged on the three-dimensional insulation mask in the step S2, so that in the selective electrochemical deposition process, the electrolyte can flow and circulate through the three-dimensional flow channel structure, and deposition processing of metal ions on the surface to be processed in the heating pattern region is realized.

Further, in S2, the three-dimensional insulating mask is covered on the surface to be processed and fixed by a jig, the surface to be processed of the heating pattern area is connected with the negative electrode of the power supply, and the positive electrode of the power supply is connected with the copper sheet or the copper rod.

Further, the distance between the anode and the cathode in S2 is 3-8 cm, and in the selective electrochemical deposition processing process, the power supply applies direct current or pulse voltage to enable metal ions in the electrolyte to be deposited on the surface to be processed which is not covered by the bottom of the mask.

Further, in S2, the heating property and flexibility of the flexible micro-heater are tuned by the conductivity design of the graphene material and the geometric dimension design of the graphene pattern.

The second purpose of the invention is to protect a flexible micro-heater prepared by the processing method, wherein the flexible micro-heater comprises a flexible polyimide film substrate, a graphene heating pattern area, electrodes, an interconnection conductor and an encapsulation layer.

Compared with the traditional preparation and processing method of the flexible micro-heater, the invention has the following technical advantages:

1) the composite processing method adopted by the technical scheme has the advantages that the cost is low, the local pattern precision of the micro-heater can reach the micro-nano scale, the local heating pattern can be customized at will, the processing technology is simple to operate and environment-friendly, and large-scale device production can be carried out.

2) The technical scheme combines laser direct writing etching, 3D printing and selective electrochemical deposition processing technologies, and can flexibly customize and process the flexible micro heater for heating a specific micro area.

3) The micro-heater prepared by the technical scheme has high flexibility and mechanical stability, high heating speed and high localized heating precision, can locally heat to 170 ℃, patterns of a heating area can be randomly designed and distributed according to the requirements of specific applications, and the steady-state heating temperature of the heating area can be adjusted and controlled.

4) The technical scheme is a flexible and adjustable composite processing method, has the advantages of convenient operation of the processing technological process, environmental protection, high processing precision and low cost, has important application value for the development and processing of flexible micro-heating devices, and the processed flexible micro-heater can be widely applied to various fields of biomedical treatment, wearable electronic equipment, laboratory research, intelligent electronic devices, soft robots and the like.

Drawings

FIG. 1 is a schematic diagram of the principles of the present invention;

wherein 1 is the whole structure of the flexible micro-heater, 2 is the insulating film substrate, 3 is the laser-induced graphene pattern layer, and 4 is the insulating mask;

FIG. 2 is a process flow diagram of the composite process of the flexible microheater of the present invention;

FIG. 3 shows typical graphene patterns on the surface of a polyimide film substrate under different laser direct write etching parameters;

fig. 4 is a partial enlarged view of typical graphene subjected to laser direct writing etching under an optical microscope and a Scanning Electron Microscope (SEM);

FIG. 5 is a photograph of a typical 3D printing reticle and an enlarged view under an optical microscope;

FIG. 6 is a pattern of a copper array for selective electrochemical deposition;

FIG. 7 is a pictorial view of a typical flexible microheater heating performance test;

FIG. 8 is a graph of the relationship between the surface temperature of the heating pattern and the heating time for different voltage amplitudes.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

The technical scheme develops a novel composite processing preparation method, three processing methods of laser direct writing etching (DLW), 3D printing and Selective Electrodeposition (SED) are combined, the customizable flexible micro-heater can be manufactured with low cost and high precision, and the preparation method is suitable for processing large-scale devices.

The composite processing method for flexibly customizing the high-adjustable flexible micro-heater in the technical scheme combines three processing technologies of laser direct writing etching, 3D printing and selective electrochemical deposition. Firstly, carrying out direct-writing etching processing on the surface of a flexible substrate by utilizing a laser direct-writing technology to obtain a patterned laser-induced graphene structure as a heating pattern area; then, processing a three-dimensional insulating mask for selective electrochemical deposition by adopting photocuring 3D printing; secondly, obtaining an electrode and an interconnection conductor pattern by selective electrochemical deposition of a metal material or an alloy material; and finally, encapsulating the flexible polymer to be used as an encapsulation layer to finish the manufacture of the flexible micro-heater.

According to the laser direct writing technology in the technical scheme, the flexible polyimide film is used as a precursor, and the laser beam is used for performing direct writing etching processing on the surface of the flexible substrate (the surface of the polyimide film) to obtain a patterned laser-induced graphene structure which is used as a heating pattern area. The graphene material generated by laser induction has excellent conductivity, the conductivity can be adjusted by setting different laser processing parameters, and the main laser direct-writing etching processing parameters include laser intensity, scanning speed, the number of times of scanning paths and the like.

In the technical scheme, the photocuring 3D printing process is used for obtaining the three-dimensional insulating mask for selective electrochemical deposition processing, and the pattern at the bottom of the mask covers the non-deposition surface in the electrochemical deposition processing. And the mask has a three-dimensional flow channel structure, so that in the selective electrochemical deposition process, electrolyte can flow and circulate through the flow channels, and deposition processing of metal ions on the cathode is realized.

According to the selective electrochemical deposition processing technology in the technical scheme, a three-dimensional insulation mask printed by photocuring 3D is covered on the surface to be processed and fixed by a clamp, the surface to be processed is connected with a negative electrode of a power supply, a positive electrode of the power supply is connected with a copper sheet or a copper rod, the distance between the positive electrode and the negative electrode is about 3-8 cm, and in the selective electrochemical deposition processing process, the power supply applies direct current or pulse voltage to enable metal ions in electrolyte to be deposited on the surface to be processed of a cathode which is not covered by the bottom of the mask.

The flexible micro-heater in the technical scheme is composed of a flexible polyimide film substrate, a graphene heating pattern area, electrodes, an interconnection conductor and a packaging layer, and the whole structure 1 of the flexible micro-heater is shown in figure 1. The high adjustability of the micro-heater is realized by the conductivity of the graphene material in the flexible micro-heater and the geometric dimension of the graphene pattern. The flexible micro-heater has the advantages of rapid heating and stable heating performance under the conditions of folding, bending and twisting.

The technical scheme provides a novel composite processing method for obtaining the ultrathin and light flexible micro-heater with customizable heating performance, and combines laser direct writing (DLW), 3D printing and Selective Electrodeposition (SED) methods. The manufacturing process is efficient, low in cost, high in precision, convenient to operate and capable of realizing large-scale production. The micro-heater can provide a certain temperature on a specific micron pixel area, and can be attached to the surface of rigid and flexible objects with different shapes as wearable electronic devices.

Example 1

In the composite processing method for flexibly customizing the high-adjustable flexible micro-heater in the embodiment, the following steps are described, and the composite processing process flow chart in fig. 2 is shown in detail:

1) a Polyimide (PI) film (i.e., the insulating film substrate 2) having a thickness of 127 μm, as shown in fig. 1, was placed on a glass plate and fixed, ensuring that no air bubbles were present between the PI film and the glass plate, and was horizontally placed on a stage for laser direct write etching.

2) And focusing a laser beam on the PI film by adopting a blue laser with the wavelength of 405nm, and performing laser direct writing etching according to a graphene heating pattern path which is customized and designed by CAD. The scanning speed of the laser beam is 360mm/min, the laser energy is 160mW, and the number of repeated scanning is 2, so as to obtain a uniform and continuous laser-induced graphene pattern layer 3, as shown in fig. 1.

As shown in fig. 3, in this embodiment, a square graphene pattern etched at a laser scanning speed of 360mm/min and a laser energy of 20-200 mW is set. When the laser energy is low and is 20-80 mW, the laser power intensity is not enough to process and generate continuous and compact graphene patterns, so that the resistance of the patterns is large; when the laser energy is higher than 200mW, the graphene material can be directly etched; therefore, 120-160 mW is generally selected as laser processing energy to obtain a continuous and uniform graphene pattern as a heating functional layer.

As shown in fig. 4, an optical microscope image and an electron microscope image of the laser-induced processed graphene material in this embodiment are shown, where the laser scanning speed is 360mm/min and the laser energy is 160 mW;

3) designing a 3D structure diagram of an insulating mask for 3D printing, and considering the following aspects: the bottom pattern of the mask is used for directly contacting with the substrate pattern and covering the pattern of the heating area without performing the pattern of the copper film material of electrochemical deposition. In order to enable the electrolyte to obtain uniform flow and good circulation on the deposition surface, the height of a flow channel in the vertical direction of the mask is designed to be 3-8 mm.

4) Subsequently, a covering mask is processed and prepared by a Digital Light Processing (DLP)3D printer, the 3D printing material is light-cured resin, and the resolution of the light-cured 3D printer in the XY direction is about 50 μm. The mask processed by photocuring 3D printing has a smooth surface, and is favorable for ensuring the close contact between the bottom of the mask and the surface of the covered substrate. As shown in fig. 5, a typical 3D printing reticle photograph and a bottom surface local magnification under an optical microscope are shown.

5) Clamping and fixing the 3D printed mask and the PI film substrate on the glass sheet, wherein as shown in figure 1, an insulating mask 4 is in contact with a laser-induced graphite layer 3 on a PI film 2 and is used for covering a graphene heating function region without carrying out electrochemical deposition of a metal layer.

6) And performing selective electrochemical deposition of a metal copper material on the conductive graphene pattern which is not covered by the mask. A pure copper sheet of 2cm multiplied by 2cm is used as an anode of electrochemical deposition and is connected with the anode of a direct current or pulse power supply, a conductive graphene layer on a PI substrate is used as a cathode and is connected with the cathode of the power supply. The anode copper sheet is placed at a position 1-3 cm away from the cathode, and CuSO is adopted as electrolyte₄And (3) an electrolyte. The reaction rate of the electrochemical deposition can be promoted by heating the electrolyte to 50 ℃ and stirring. The amplitude of the direct current voltage is set to be 6-10V, and the electro-deposition processing time is 10-30 minutes. The electrochemical deposition reaction at the cathode is as follows:

Cu²⁺+2e^-→Cu

as shown in fig. 6, which is an optical microscope magnified view of the array pattern of copper blocks obtained after the selective electrochemical deposition process, each copper block has a geometric size of 0.8mm x 0.8 mm.

7) And finally, taking the PI film off the glass sheet, thoroughly rinsing the PI film in deionized water, drying the PI film, and packaging the PI film with one surface having viscosity on the top to form the flexible micro-heating device capable of controllably heating the designated micro-area. Fig. 7 is a physical diagram of a heating performance test of a typical flexible micro-heater.

8) Fig. 8 is a graph showing the heating performance test of a typical flexible micro-heater, i.e. the average temperature reached by the surface of the heating pattern as a function of time under different dc voltage amplitude inputs. Therefore, the flexible micro-heater prepared by the composite processing method is rapid in heating and stable in heating performance, and reaches a stable heating temperature within 1-1.5 minutes.

The invention solves the problems of high cost, complex process, easy pollution introduction, difficult large-scale production and the like of the traditional micro-nano etching flexible micro-heater, and develops a novel composite processing preparation method. The customizable flexible micro-heater is manufactured by combining three processing methods of laser direct write etching (DLW), 3D printing and Selective Electrodeposition (SED) with low cost and high precision, and the preparation method can be suitable for processing large-scale devices.

The foregoing is a more detailed description of the invention, taken in conjunction with specific preferred embodiments thereof, and it is not intended that the invention be limited to the specific details set forth herein. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.