阅读说明：本技术 一种可低温下快速打印的高导电性电子电路及其制备方法和应用 (High-conductivity electronic circuit capable of being printed quickly at low temperature and preparation method and application thereof ) 是由 不公告发明人 于 2021-09-09 设计创作，主要内容包括：本发明提供了一种可低温下快速制备高导电性电子电路的方法,包括以下步骤：将纳米金属导电墨水采用喷墨打印的方式印制电子电路,低温热固化或红外烧结表干后,再使用微烧结溶液在纳米金属电子电路表面喷墨打印、表干,最后使用液态金属涂覆在微烧结后的纳米金属电子电路表面,获得高导电性电子电路。该方法可在低温下印制高导电性电子电路,有利于拓宽打印适用范围,并可满足可穿戴电子、电子皮肤、智能传感等民用领域的应用需求。(The invention provides a method for rapidly preparing a high-conductivity electronic circuit at low temperature, which comprises the following steps: printing the nano metal conductive ink on an electronic circuit by adopting an ink-jet printing mode, carrying out low-temperature thermocuring or infrared sintering surface drying, carrying out ink-jet printing and surface drying on the surface of the nano metal electronic circuit by using a micro sintering solution, and finally coating the surface of the micro sintered nano metal electronic circuit with liquid metal to obtain the high-conductivity electronic circuit. The method can print high-conductivity electronic circuits at low temperature, is beneficial to widening the printing application range, and can meet the application requirements of civil fields such as wearable electronics, electronic skins, intelligent sensing and the like.)

1. A method of rapidly printing high conductivity electronic circuits at low temperatures, comprising the steps of:

(1) printing nano metal conductive ink on the surface of a rigid or flexible substrate in an ink-jet manner, printing a patterned electronic circuit, and drying the surface of the nano metal conductive ink by using a low-temperature thermocuring or infrared sintering manner; the low-temperature heat curing temperature is 60-100 ℃, and the low-temperature heat curing time is 10-30 min; the infrared sintering power is 10-50W, and the infrared sintering time is 3-5 min;

(2) printing a micro-sintering solution on the surface of the printed nano metal electronic circuit in an ink-jet mode, and performing surface drying by using a low-temperature thermal curing or infrared sintering mode, wherein the low-temperature thermal curing temperature is 60-100 ℃, and the low-temperature thermal curing time is 5-10 min; the infrared sintering power is 10-50W, and the infrared sintering time is 3-5 min;

(3) and coating the gallium-based liquid alloy on the surface of the printed and micro-sintered nano metal electronic circuit to obtain the high-conductivity electronic circuit.

2. The method of claim 1, wherein the rigid substrate is a PCB, alumina ceramic, aluminum nitride ceramic, aluminum substrate or copper substrate.

3. The method of claim 1, wherein the flexible substrate is bare PET, PEN or PI.

4. The method of claim 1, wherein the method of preparing the nanometal conductive ink comprises: nano metal and a mixed solvent are mixed according to the mass ratio of (0.2-0.5): 1, ball milling for 2-12 h at the rotation speed of 100-500 rpm, wherein the viscosity of the prepared nano metal conductive ink is 5-20 cp.

5. The method of claim 4, wherein the nano-metal comprises one or more of nano-gold, nano-silver, nano-copper, and nano-nickel.

6. The method of claim 5, wherein the silver nanoparticles comprise one or more of spherical silver nanoparticles and icosahedral silver nanoparticles; the average particle size of the spherical particle nano silver powder is 50-200 nm, and the average particle size of the icosahedral nano silver powder is 100-300 nm.

7. The method of claim 4, wherein the solvent mixture comprises two or more of ethanol, ethylene glycol, diethylene glycol, propylene glycol, glycerol, and n-hexanol.

8. The method of claim 1, wherein the micro-sintering solution is one or more selected from the group consisting of NaOH solution, propylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, and ethylene glycol dimethyl ether, and the PH of the micro-sintering solution is 5 to 13.

9. The method of claim 1, wherein the liquid metal is selected from the group consisting of liquid metal based on gallium and indium, liquid metal based on gallium and zinc, metal gallium 65-85 parts by weight, metal indium 10-20 parts by weight, and metal zinc 0-30 parts by weight.

10. The highly conductive electronic circuit prepared by the method of any of claims 1 to 9, wherein the electronic circuit meets the application requirements of wearable devices, electronic skins and intelligent sensing.

Technical Field

The invention relates to the technical field of electronic circuits, in particular to a high-conductivity electronic circuit capable of being printed quickly at low temperature and a preparation method thereof.

Background

Electronic equipment is gradually developing towards intellectuality, flexibility, integration and frivolousization at present. The flexible printed electronics adopts the printing process to prepare the flexible device, and has the characteristics of low cost, simple process, intelligent design and the like. The green, material-increasing and rapid preparation of the basic circuit can be realized by combining the conductive ink with the printing technology. Among them, conductive ink, printing technology and post-processing process determine the performance of the flexible printed circuit. Conductive inks are key materials in the core, and technological advances have been made in printed circuits to achieve a faster and more widely used substrate in electronic products.

Currently, metal-based conductive inks, including gold, silver, copper, platinum, etc., are more commonly used in conductive inks. The preparation method also comprises various types such as mechanical ball milling, liquid phase method, vacuum deposition and the like. However, the nano-metal prepared by the liquid phase method can reach the nano-scale size and has higher yield. However, because the organic coating agent exists on the surface of the nano metal particles, and the coating agent is an organic polymer material, which can affect the conductivity of the nano technical particles, in the actual production, inorganic conductive ink such as nano silver and nano copper ink must be subjected to curing and sintering treatment after being printed into a circuit to have conductivity and sufficient adhesion. The conventional process uses a hot furnace or hot plate (vacuum or inert gas environment is also required for copper ink), requires a long processing time, and has a long production line in case of the R2R process and may damage the temperature sensitive substrate. Particularly, substrates such as PEN, PVC, PI, and the like are mostly flexible, light, thin, and unable to withstand high-temperature sintering, so the problem that the nano metal ink needs high-temperature sintering treatment after printing is more significant, and the application and development thereof are limited.

Accordingly, the present invention provides a high conductivity electronic circuit that can be printed quickly at low temperatures and a method of making the same. Through the two-step micro-sintering process, the micro-sintering liquid and the liquid metal are sequentially adopted to treat the nano metal conductive ink for ink-jet printing, so that organic ligands on the surfaces of nano metal particles can be removed, and the conductivity, flexibility and substrate applicability of the electronic circuit are improved, therefore, the application range of the electronic circuit prepared by the nano metal conductive ink for ink-jet printing can be enlarged, and the industrial application is expected to be promoted.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention aims to provide a rapid printing method for preparing a high-conductivity electronic circuit at low temperature, which can realize the rapid curing of nano metal materials through low-temperature sintering, improve the conductivity, the stretchability and the substrate adhesion strength of the nano metal materials, can be suitable for substrates with poor temperature resistance such as PVC, PI and the like, and obviously broadens the printing application range. Meanwhile, the electronic circuit prepared by the method can be more flexibly connected with different types of electronic elements, rigid and flexible substrates, and can meet the application requirements of civil fields such as wearable electronics, electronic skin and intelligent sensing.

The specific technical scheme is as follows: the invention provides a method for quickly preparing a high-conductivity electronic circuit at low temperature, which comprises the following steps:

(1) printing nano metal conductive ink on the surface of a rigid or flexible substrate in an ink-jet manner, printing a patterned electronic circuit, and drying the surface of the nano metal conductive ink by using a low-temperature thermocuring or infrared sintering manner; the low-temperature heat curing temperature is 60-100 ℃, and the low-temperature heat curing time is 10-30 min; the infrared sintering power is 10-50W, and the infrared sintering time is 3-5 min;

(2) printing a micro-sintering solution on the surface of the printed nano metal electronic circuit in an ink-jet mode, and performing surface drying by using a low-temperature thermal curing or infrared sintering mode, wherein the low-temperature thermal curing temperature is 60-100 ℃, and the low-temperature thermal curing time is 5-10 min; the infrared sintering power is 10-50W, and the infrared sintering time is 3-5 min. The micro-sintering solution which is ink-jet printed on the surface of the nano metal conductive ink plays a micro-sintering role on nano metal particles, promotes secondary growth and bonding of the nano metal particles into sheets, and improves the conductivity of an electronic circuit;

(3) and coating the gallium-based liquid alloy on the surface of the printed and micro-sintered nano metal electronic circuit to obtain the high-conductivity electronic circuit.

The rigid substrate is a PCB (printed Circuit Board), an alumina ceramic plate, an aluminum nitride ceramic plate, an aluminum substrate or a copper substrate; the flexible substrate is bare PET, PEN or PI. The selected rigid or flexible substrate can be used for preparing an electronic circuit by adopting a mode of ink-jet printing of nano metal ink, and the liquid metal cannot be attached to the surface of the substrate, so that the phenomenon that the liquid metal forms a conductive path outside the patterned electronic circuit on the surface of the substrate to damage the printing quality and the printing precision of the electronic circuit is avoided.

The preparation method of the nano metal conductive ink comprises the following steps: nano metal and a mixed solvent are mixed according to the mass ratio of (0.2-0.5): 1, ball milling for 2-12 h at the rotation speed of 100-500 rpm, wherein the viscosity of the prepared nano metal conductive ink is 5-20 cp.

The nano metal comprises one or more of nano gold, nano silver, nano copper and nano nickel. The nano silver comprises one or more of spherical particle nano silver powder and icosahedron nano silver powder, the average particle size of the spherical particle nano silver powder is 50-200 nm, and the average particle size of the icosahedron nano silver powder is 100-300 nm. The properties of metal nanomaterials depend largely on the shape, size, composition, crystallinity and structure of the particles, and the smaller the particles of nanoscale metal particles are, the more easily they can be sintered into lumps at low temperature.

The mixed solvent comprises more than two of ethanol, ethylene glycol, diethylene glycol, propylene glycol, glycerol and n-hexanol.

The micro-sintering solution is one or more of NaOH solution, propylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether and ethylene glycol dimethyl ether, and the pH value of the micro-sintering solution is 5-13. The nano metal conductive ink treated by the micro sintering solution has the advantages that the micro sintering effect can obviously improve the sintering speed of the nano metal ink, the nano metal can be ensured to obtain better sintering quality, the sintered metal film layer has better conductivity and density, and the surface smoothness of a microstructure is also better.

The gallium-based liquid metal is gallium-indium-based liquid metal and gallium-indium-zinc-based liquid metal, and 65-85 parts by mass of metal gallium, 10-20 parts by mass of metal indium and 0-30 parts by mass of metal zinc. If the nano metal conductive ink is subjected to micro sintering treatment only by using a micro sintering solution or a liquid metal alloy, the conductivity of the electronic circuit cannot be remarkably improved at low temperature. If the micro-sintering is first performed and then the micro-sintering process is performed using a liquid metal, it is advantageous to obtain a highly conductive electronic circuit at a low temperature. However, if the liquid metal is first micro-sintered and then treated with a micro-sintering solution, the micro-sintering solution may cause the liquid metal to be dissolved, thereby reducing the sintering effect of the electronic circuit. Therefore, after the nano metal ink is printed firstly, and then the micro sintering solution is coated, and finally the micro sintering treatment is carried out by using the liquid alloy, the liquid alloy can be attached to the nano metal surface and can not be attached to the printing substrate.

The high-conductivity electronic circuit can meet the application requirements of wearable electronics, electronic skin and intelligent sensing.

The invention has the beneficial effects that: the invention provides a high-conductivity electronic circuit capable of being rapidly printed at low temperature and a preparation method thereof. Meanwhile, the liquid metal is filled into gaps of the nano metal particles, so that the electric connection line and the electric conductivity of the electronic circuit are improved, a more efficient electric transmission channel is constructed, and the electric conductivity of the electronic circuit is improved. Furthermore, the fluidity and stretchability of the liquid metal can further improve the problem of poor conductivity after stretching of the electronic circuit. The nano metal prepared by the method can form reliable connection with a flexible substrate and can well resist mechanical damage. In addition, the method can be operated at low temperature, so that the method has high applicability to PVC, PI and other substrates with poor temperature resistance, can remarkably widen the application range of the nano metal conductive ink, and can meet the application requirements of civil fields such as wearable electronics, electronic skin, intelligent sensing and the like.

Drawings

FIG. 1 is an SEM image of a nano-silver electronic circuit after treatment of a micro-sintering liquid and a liquid metal in example 1 of the invention;

FIG. 2 is a SEM image of an electronic circuit of the inkjet printed nano-silver conductive ink of comparative example 1 of the present invention after surface drying;

FIG. 3 is an SEM image of an electronic circuit treated with a micro-sintering fluid after the surface of the ink-jet printed nano-silver conductive ink of comparative example 2 of the present invention is dried;

fig. 4 is an SEM image of an electronic circuit treated with a liquid metal after the surface of the inkjet-printed nano-silver conductive ink of comparative example 3 of the present invention was dried.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following examples and accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In order to solve the problems that organic ligands exist on the surface of nano metal prepared by a liquid phase method in the prior art, high-temperature sintering is needed when an electronic circuit is prepared, and the selectivity to a substrate is strong, the stretchability, the adhesion property and the like are poor, a rapid printing method capable of preparing a high-conductivity electronic circuit at a low temperature is designed, the low-temperature sintering and rapid curing of the nano metal material can be realized, the conductivity, the stretchability and the substrate adhesion strength of the nano metal material are improved, the method is applicable to substrates with poor temperature resistance such as PVC (polyvinyl chloride), PI (polyimide), and the like, and the printing application range is remarkably widened. Meanwhile, the electronic circuit prepared by the method can be more flexibly connected with different types of electronic elements, rigid and flexible substrates, and can meet the application requirements of civil fields such as wearable electronics, electronic skin and intelligent sensing. The embodiment of the rapid printing method for preparing the high-conductivity electronic circuit at low temperature provided by the invention is as follows.

Example 1

A method of rapidly printing high conductivity electronic circuits at low temperatures comprising the steps of:

(1) printing nano-silver conductive ink on the surface of the PCB in an ink-jet manner, printing a patterned electronic circuit, and drying the surface of the nano-silver conductive ink in a low-temperature thermosetting manner; the low-temperature heat curing temperature is 100 ℃, and the low-temperature heat curing time is 30 min;

(2) printing a micro-sintering solution on the surface of a printed nano-silver electronic circuit in an ink-jet printing mode, and performing surface drying in a low-temperature thermosetting mode, wherein the low-temperature thermosetting temperature is 60 ℃, and the low-temperature thermosetting time is 10 min; the micro-sintering solution is a mixture of propylene glycol methyl ether acetate, diethylene glycol diethyl ether and dipropylene glycol dimethyl ether;

(3) and (3) coating the gallium-based liquid alloy on the surface of the printed and micro-sintered nano-silver electronic circuit to obtain the high-conductivity electronic circuit, wherein the resistance of the electronic circuit is 0.7 omega. The gallium-based liquid metal comprises 85 parts by mass of metal gallium and 15 parts by mass of metal indium.

The preparation method of the nano-silver conductive ink comprises the following steps: mixing nano silver powder and a mixed solvent according to a mass ratio of 0.5: 1, ball milling for 7 hours at the rotating speed of 500 rpm, wherein the viscosity of the nano-silver conductive ink is 8 cp; the nano silver powder is spherical particle nano silver powder, and the average particle size of the spherical particle nano silver powder is 50 nm; the mixed solvent is a mixture of ethylene glycol and diethylene glycol.

Fig. 1 is an SEM image of a nano silver electronic circuit after micro-sintering liquid and liquid metal treatment in example 1 of the present invention. The prepared nano-silver electronic circuit can meet the application requirements of wearable equipment, electronic skin and intelligent sensing.

In another embodiment, the PCB board in example 1 may be replaced with an alumina ceramic board, an aluminum nitride ceramic board, an aluminum substrate, or a copper substrate.

Example 2

A method of rapidly printing high conductivity electronic circuits at low temperatures comprising the steps of:

(1) printing nano-gold conductive ink on the surface of the bare PET in an ink-jet manner, printing a patterned electronic circuit, and drying the surface of the nano-gold conductive ink in an infrared sintering manner; the infrared sintering power is 10W, and the infrared sintering time is 5 min;

(2) printing a micro-sintering solution on the surface of the printed nano-gold electronic circuit in an ink-jet printing mode, and performing surface drying in an infrared sintering mode, wherein the infrared sintering power is 50W, and the infrared sintering time is 3 min; the micro-sintering solution is a mixture of ethylene glycol ethyl ether acetate and diethylene glycol diethyl ether;

(3) and coating the gallium-based liquid alloy on the surface of the nano-gold electronic circuit after printing and micro-sintering treatment to obtain the high-conductivity electronic circuit, wherein the resistance of the electronic circuit is 0.3 omega. The gallium-based liquid metal comprises 70 parts by mass of metal gallium, 20 parts by mass of metal indium and 20 parts by mass of metal zinc.

The preparation method of the nano gold conductive ink comprises the following steps: nano gold powder and a mixed solvent are mixed according to the mass ratio of 0.2: 1, ball milling for 2 hours at the rotating speed of 100 rpm, wherein the viscosity of the nanogold conductive ink is 20 cp; the mixed solvent is a mixture of diethylene glycol, propylene glycol and n-hexanol.

The prepared nanogold flexible electronic circuit can meet the application requirements of wearable equipment, electronic skin and intelligent sensing.

Example 3

A method of rapidly printing high conductivity electronic circuits at low temperatures comprising the steps of:

(1) carrying out ink-jet printing on the surface of the PI with nano-copper conductive ink, printing a patterned electronic circuit, and drying the surface of the nano-copper conductive ink in a low-temperature thermosetting mode; the low-temperature heat curing temperature is 60 ℃, and the low-temperature heat curing time is 10 min;

(2) printing a micro-sintering solution on the surface of a printed nano-copper electronic circuit in an ink-jet printing mode, and performing surface drying in a low-temperature thermosetting mode, wherein the low-temperature thermosetting temperature is 100 ℃, and the low-temperature thermosetting time is 5 min; the micro-sintering solution is a mixture of diethylene glycol diethyl ether, dipropylene glycol dimethyl ether and ethylene glycol dimethyl ether;

(3) and (3) coating the gallium-based liquid alloy on the surface of the printed and micro-sintered nano-copper electronic circuit to obtain the high-conductivity electronic circuit, wherein the resistance of the electronic circuit is 0.5 omega. The gallium-based liquid metal comprises 65 parts by mass of metal gallium, 10 parts by mass of metal indium and 30 parts by mass of metal zinc.

The preparation method of the nano-copper conductive ink comprises the following steps: mixing nano copper powder and a mixed solvent according to a mass ratio of 0.35: 1, ball milling for 12 hours at the rotating speed of 300 rpm, wherein the viscosity of the nano-copper conductive ink is 5 cp; the mixed solvent is a mixture of ethanol, ethylene glycol, glycerol and n-hexanol.

The prepared nano-copper flexible electronic circuit can meet the application requirements of wearable equipment, electronic skin and intelligent sensing.

Comparative example 1

The technical scheme in the embodiment 1 is changed into that a micro-sintering solution and liquid metal are not used, a high-conductivity electronic circuit cannot be obtained at low temperature, and the resistance of the electronic circuit is 10M omega. Fig. 2 is an SEM image of an electronic circuit of inkjet printed nano silver conductive ink of comparative example 1 according to the present invention after surface drying.

Comparative example 2

The technical solution in example 1 was changed to use only the micro-sintering solution, and a conductive electronic circuit could be obtained at a low temperature, but the conductivity was poor and the resistance of the electronic circuit was 8k Ω. Fig. 3 is an SEM image of an electronic circuit treated with a micro-sintering fluid after the surface of the inkjet-printed nano-silver conductive ink of comparative example 2 of the present invention was dried.

Comparative example 3

The technical solution in embodiment 1 is changed to use only liquid metal, so that a conductive electronic circuit can be obtained in a low temperature state, but the conductivity is poor, and the resistance of the electronic circuit is 10k omega. Fig. 4 is an SEM image of an electronic circuit treated with a liquid metal after the surface of the inkjet-printed nano-silver conductive ink of comparative example 3 of the present invention was dried.

Comparative example 4

By reversing the sequence of step (2) and step (3) in example 1, i.e. using the liquid metal for micro-sintering first and then using the micro-sintering solution, the micro-sintering solution is selected to dissolve the liquid metal, resulting in a significant reduction in the micro-sintering and gain effects of the liquid metal, or even no longer serving any role, thereby reducing the sintering effect of the electronic circuit.

The mode of micro-sintering and then liquid metal sintering treatment is used, so that the high-conductivity electronic circuit can be obtained at low temperature.

Comparative example 5

When a PVC material is selected as the printing substrate, since the liquid metal also adheres to the PVC, the use of the method of coating the nano-silver electronic circuit causes a part of the liquid metal to remain on the PVC substrate, and thus a high-precision electronic circuit cannot be obtained. Thus, the present invention employs bare PET, PEN, or PI as the substrate.

From the above, the nano metal material of the high-conductivity electronic circuit prepared by the embodiment of the invention can be rapidly cured by low-temperature sintering, so that the conductivity, the stretchability and the substrate adhesion strength of the high-conductivity electronic circuit are improved, the high-conductivity electronic circuit can be suitable for substrates with poor temperature resistance such as PVC (polyvinyl chloride), PI (polyimide), and the like, and the printing application range is remarkably widened. Meanwhile, the electronic circuit prepared by the method can be more flexibly connected with different types of electronic elements, rigid and flexible substrates, and can meet the application requirements of civil fields such as wearable electronics, electronic skin and intelligent sensing.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.