3D printed circuit and method of making, soldering method and use

Abstract

The application discloses a 3D printed circuit and a preparation method, a welding method and an application thereof, and relates to the field of antennas. Specifically, the 3D printed circuit comprises a carrier, a printed circuit printed on the carrier and one or more solder pads printed on the printed circuit; the printed circuit is obtained by inkjet printing of conductive silver paste, the solder pads are obtained by inkjet printing of conductive copper paste, the resistivity of the conductive copper paste is 50*10 ‑3 Ω·cm-70*10 ‑3 Ω·cm, and the thickness of the solder pads is greater than 80 μm. By implementing the application, the 3D printed circuit is endowed with weldability, and the application field of the 3D printed circuit is greatly widened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, in particular to a 3D printed circuit, a preparation method thereof, a welding method and application. BACKGROUND

[0002] With the development of wireless communication technology, the increase of communication frequency bands and the increase of communication frequency, the preparation of antennas becomes more and more difficult. In addition, with the increasing miniaturization of communication devices (such as mobile phones, smart watches, tablets, computers), traditional printed circuit board type antennas (such as FPC type antennas, PCB type antennas) have been difficult to apply. The development of new devices and new technologies requires that the layout of antennas be performed on the shell and other curved surfaces of communication devices, therefore, three-dimensional curved surface antennas are very important, especially since the models of communication devices are changing, the preparation process of three-dimensional curved surface antennas is highly required. The mainstream three-dimensional curved surface antenna is an LDS antenna, and its specific preparation process is: LDS special metal composite material preparation, mold injection, LDS engraving, chemical plating (copper plating, nickel plating, gold plating), and secondary processing such as spraying. The LDS process has the characteristics of particularity, complexity and environmental unfriendliness: the process is complex, and involves chemical plating and spraying, which pollutes the environment.

[0003] In order to solve the above problems of the LDS antenna, a new type of antenna, PDS antenna, is proposed in the industry, and its general process is: exposing and developing etching on a steel plate using a photosensitive glue, printing a pattern on the product shell by a special glue head through a pad printing machine, and then making the final antenna through heat curing. The advantages of this technology are that it can directly print a circuit, does not require special laser modified materials, does not need to be engraved, plated or sprayed, has low cost and strong environmental protection. However, it is also limited by the performance of the antenna and the production process of PDS, so that the PDS process can generally only use silver paste. The silver paste circuit cannot be welded after solidification. This makes the connection method rely only on the contact of the spring piece to connect the main board or other components, and the disadvantage is that the signal is unstable, and with the passage of time, the contact surface wears out and eventually leads to open circuit, which seriously affects the signal stability and service life of the antenna. This disadvantage limits the application of the PDS antenna. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a 3D printed circuit having weldability.

[0005] The technical problem to be solved by the present application is to provide a 3D printed circuit having weldability.

[0006] The technical problem to be solved by the present application is to provide a 3D printed circuit having weldability.

[0007] The technical problem solved by the present application is to provide an application of a 3D printed circuit as an antenna.

[0008] In order to solve the technical problem, the present application provides a 3D printed circuit, comprising a carrier, a printed circuit printed on the carrier, and one or more pads printed on the printed circuit.

[0009] The printed circuit is obtained by inkjet printing of conductive silver paste, and the pad is obtained by inkjet printing of conductive copper paste, the resistivity of the conductive copper paste being 50×10 -3 Ω·cm-110×10 -3 Ω·cm, and the thickness of the pad being greater than 80 μm.

[0010] As an improvement of the above technical solution, the content of copper powder in the conductive copper paste is 60%-80%.

[0011] As an improvement of the above technical solution, the conductive copper paste mainly comprises the following components:

[0012] Copper powder 60%-80%, binder 3%-10%, organic solvent 17%-30%, and additive 0-5%.

[0013] As an improvement of the above technical solution, the copper powder is nano copper powder, and the average particle size is 20 nm-500 nm.

[0014] And / or, the binder is selected from one or more of ethyl cellulose, cellulose derivatives, epoxy resin, phenolic resin, acrylic resin, and polyamide resin.

[0015] And / or, the organic solvent is selected from one or more of terpineol, benzyl alcohol, tertiary alcohol amine, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, diethyl phthalate, butyl carbitol acetate, dibutyl phthalate, and dioctyl phthalate.

[0016] And / or, the additive is selected from a surfactant and / or a silane coupling agent; the silane coupling agent is selected from KH-570, KH-560, or KH-550; and the surfactant is selected from lecithin, triethanolamine, or sorbitan trioleate.

[0017] As an improvement of the above technical solution, the content of copper powder with a particle size of 20 nm-80 nm is 30%-40% of the total content of copper powder, and the content of copper powder with a particle size of 80 nm-200 nm is 20%-30% of the total content of copper powder.

[0018] Correspondingly, the present application also discloses a preparation method of a 3D printed circuit, for preparing the above 3D printed circuit, which comprises:

[0019] (1) using conductive silver paste to form printed circuit on the carrier;

[0020] (2) printing one or more pads on the preset area of the printed circuit, and then curing at 90-150℃ for 10-60min.

[0021] As an improvement of the above technical solution, in step (1), conductive silver paste is printed on the carrier, and then preliminary curing is performed at 40-60℃ for 20-60min.

[0022] In step (2), one or more pads are printed on the preset area of the printed circuit, and then curing is performed at 90-150℃ for 10-60min.

[0023] Correspondingly, the application also discloses a soldering method of the 3D printed circuit, which comprises:

[0024] (i) providing the above 3D printed circuit;

[0025] (ii) soldering the component to be soldered to the pad; wherein the melting temperature of the solder used for soldering is <400℃;

[0026] (iii) forming an oxidation-resistant layer on the surface of the pad.

[0027] As an improvement of the above technical solution, in step (ii), low-temperature tin wire is used to solder the component to be soldered to the pad; wherein the melting point of the low-temperature tin wire is 180-220℃.

[0028] Correspondingly, the application also discloses the application of the above 3D printed circuit as an antenna.

[0029] The implementation of the application has the following beneficial effects:

[0030] 1. The 3D printed circuit of the application comprises a carrier, a printed circuit printed on the carrier and one or more pads printed on the printed circuit; the printed circuit is obtained by inkjet printing of conductive silver paste, the pad is obtained by inkjet printing of conductive copper paste, the resistivity of the conductive copper paste is 50*10 -3 Ω·cm-110*10 -3 Ω·cm, and the thickness of the pad is >80μm. Based on the above structure of the printed circuit, other components can be directly soldered to the pad, which greatly widens the application field of the 3D printed circuit. Specifically, the 3D printed circuit of the application can be used as an antenna of a mobile phone, a smart watch, a tablet computer and other communication equipment, and can also be applied to other fine circuits.

[0031] 2.The conductive copper paste for 3D printed circuit is developed by the application, and the formula of the conductive copper paste is as follows: 60-80% of copper powder, 3-10% of binder, 17-30% of organic solvent, and 0-5% of additive, and the conductive copper paste has the advantages of high bonding strength, strong thermal conductivity, strong electrical conductivity, and stable contact resistance, can be used as a good pad substrate, and is integrated with the printed circuit to guarantee the circuit stability of the 3D printed circuit. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a structural schematic diagram of a 3D printed circuit in an embodiment of the application;

[0033] Figure 2 is a structural schematic diagram of a carrier in an embodiment of the application;

[0034] Figure 3 is an electron microscope image of copper powder in an embodiment of the application;

[0035] Figure 4 is a flow chart of a preparation method of a 3D printed circuit in an embodiment of the application;

[0036] Figure 5 is a flow chart of a welding method of a 3D printed circuit in an embodiment of the application. DETAILED DESCRIPTION

[0037] To make the object, technical scheme and advantages of the application clearer, the application will be further described in detail below with reference to the specific embodiments.

[0038] As a first aspect of the application, the application provides a 3D printed circuit, as shown in the figure, comprising a carrier 1, a printed circuit 2 and a pad 3; wherein the printed circuit 2 and the pad 3 are conductively connected. Figure 1 Referring to

[0039] , the carrier 1 at least comprises a first printing surface 11, the first printing surface 11 is provided with a first pattern area 111, and the printed circuit 2 is obtained by inkjet printing of conductive silver paste on the first pattern area 111. In addition, the printed circuit 2 is provided with a second pattern area, and the pad 3 is obtained by inkjet printing of conductive copper paste on the second pattern area. Figure 2 The first printing surface 11 of the application can be a planar structure, or a curved surface structure, a concave-convex structure, etc. In addition, the carrier 1 of the application can comprise other printing surfaces in addition to the first printing surface 11, and the printed circuit and the pad can also be formed on the other printing surfaces, and the printed circuits on different printing surfaces can be conductive or non-conductive.

[0040]

[0041] ​The present application prints a solder pad formed by conductive copper paste on a printed circuit, so that the 3D printed circuit has solderability, and other circuits and electronic components can be soldered at will.

[0042] The conductive copper paste has a resistivity, which can maintain good ohmic contact between the printed circuit, the solder pad and other electronic components connected to the solder pad, and avoid affecting the performance of the point.

[0043] The thickness of the solder pad can be controlled to have high adhesion strength, so as to ensure the connection stability of the 3D printed circuit and other circuits and electronic components connected to the solder pad, prevent loosening, and improve the stability of the signal.

[0044] Specifically, the resistivity of the conductive copper paste is 50×10 -3 Ω·cm-110×10 -3 Ω·cm, and the thickness of the solder pad is greater than 80μm. It should be noted that when the resistivity of the conductive copper paste is greater than 110×10 -3 Ω·cm, the overall power consumption of the 3D printed circuit will increase, and even the electrical performance will be affected. When the resistivity of the conductive copper paste is less than 50×10 -3 Ω·cm, the viscosity and adhesion strength of the conductive copper paste will be affected, and then the solderability and adhesion of the solder pad will be affected.

[0045] The thickness of the solder pad is greater than 80μm to ensure that the solder pad has a sufficient base to form a solder joint with soldering for soldering wires or electronic components. In addition, the higher thickness of the solder pad also makes it have sufficient connection strength, which can meet various reliability verification tests. Preferably, the thickness of the solder pad is 100μm-200μm. If the thickness of the solder pad is too thin, the bonding force is weak and there is a risk of soldering. If the solder pad is too thick, it will affect the assembly of other components. The width of the solder pad is less than or equal to the width of the printed circuit, and preferably the width of the solder pad is less than 80% of the width of the printed circuit, so as to improve the contact resistance stability of the printed circuit and the solder pad.

[0046] The viscosity of the conductive copper paste is 200dPa·s-400dPa·s, and the conductive copper paste with such viscosity can ensure that the solder pad has a regular shape, sufficient flow leveling and sufficient filling. Preferably, in one embodiment of the present application, the viscosity of the conductive copper paste is 250dPa·s-350dPa·s.

[0047] In order to control the resistivity of the conductive copper paste to be 50×10 -3 Ω·cm-100×10 -3Within the Ω·cm range, the copper powder content in the conductive copper paste is 60%-80%. When the copper powder content is outside this range, the viscosity and resistivity of the conductive copper paste are difficult to meet the requirements. Theoretically, the lower the resistivity of the conductive copper paste, the better. However, research has found that the resistivity of the conductive copper paste does not decrease with increasing copper powder content; at a certain copper powder content, the resistivity of the conductive copper paste reaches its peak. Preferably, the copper powder content in the conductive copper paste is 60%-65%, or 75%-80%.

[0048] More preferably, in one embodiment of the present invention, the conductive copper paste comprises the following components by weight percentage: 60%-80% copper powder, 3%-10% binder, 17%-30% organic solvent, and 0-5% additives. The copper powder is nano-copper powder with an average particle size of 20nm-300nm.

[0049] Preferably, such as Figure 3 As shown, the content of copper powder with a particle size of 20nm-80nm accounts for 30%-40% of the total copper powder content, and the content of copper powder with a particle size of 80nm-200nm accounts for 20%-30% of the total copper powder content. Extensive research has found that controlling the content of copper powder with particle sizes of 20nm-80nm and 80nm-200nm within these ranges not only controls the resistivity of the conductive copper paste within a suitable range, ensuring good ohmic contact between the printed circuit board and the pads, and other electronic components connected to the pads, but also improves the bonding force between the copper powder particles and the bonding force between the conductive copper paste-formed pads and the electronic components. Specifically, the pads can withstand pull forces exceeding 10N.

[0050] Controlling the content of copper powder with a particle size of less than 20nm to between 5% and 15% of the total copper powder content is beneficial to improving the conductivity of the pads formed by conductive copper paste. Theoretically, the more copper powder with a particle size of less than 20nm, the better. However, research has found that when the content of copper powder with a particle size of less than 20nm exceeds 20% of the total copper powder content, the bonding strength of the pads formed by conductive copper paste will decrease.

[0051] The adhesive may be one or more of ethyl cellulose, cellulose derivatives, epoxy resin, phenolic resin, acrylic resin, and polyamide resin. Epoxy resin is preferred.

[0052] The amount of adhesive used is 3%-10% of the mass of the conductive copper paste. When the amount of adhesive is less than 3%, the viscosity of the conductive copper paste is too low, and it is easy to overflow the preset graphic area after inkjet printing, causing a short circuit. When the amount of adhesive is greater than 10%, the viscosity of the conductive copper paste is too high, and it is easy to clog the print head.

[0053] The organic solvent can be one or more of terpineol, benzyl alcohol, tertiary alcohol amine, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, diethyl phthalate, butyl carbitol acetate, dibutyl phthalate, dioctyl phthalate. Preferably, diethyl phthalate.

[0054] The additive can be a surfactant and / or a silane coupling agent. The surfactant can improve the surface tension of the conductive copper paste, and increase the bonding force of the conductive copper paste with the substrate. Preferably, lecithin, triethanolamine or sorbitan trioleate is used.

[0055] Similarly, the silane coupling agent can improve the bonding force of the conductive copper paste with the substrate. Preferably, KH-570, KH-560 or KH-550 is used.

[0056] Based on the above-mentioned components and compositions, the conductive copper paste has one of the following advantages: high connection strength (i.e. high connection strength of the copper powder, the binder molecules and the connected object), good toughness after connection, and high connection reliability; high contact resistance stability; and good oxidation resistance.

[0057] The substrate is one or more of PC resin, ABS resin, PA resin, LCP resin, POM resin, PPO resin, PI resin, PP resin, PET resin or glass fiber, and preferably PC resin and / or ABS resin.

[0058] The conductive silver paste is a commonly used conductive silver paste in the art, such as AlwayStone-AS6088 or AlwayStone-AS6089, but is not limited thereto. Preferably, in one embodiment of the present application, the viscosity of the conductive silver paste is controlled to be 80 dPa·s-200 dPa·s (RION VT 04F viscometer, 25℃, 2# rotor), and within this viscosity range, the printed circuit has no defects such as glue overflow, leveling, and missing printing.

[0059] Further, in another embodiment of the present application, the peel force of the conductive silver paste after preliminary curing at 40℃-60℃ is controlled to be ≥2N, and based on this control, after printing the conductive silver paste, preliminary curing can be performed for printing the conductive copper paste, without the need for high-temperature curing of the conductive silver paste before printing, thereby improving the preparation efficiency. Preferably, the adhesive strength of the conductive silver paste after preliminary curing at 40℃-60℃ is 2.5MPa-4MPa, and when the adhesive strength after preliminary curing is too large, it means that the curing degree is too high, and the matching of the solder pad with the printed circuit in the previous stage is poor.

[0060] Further, in another embodiment of the present application, the sheet resistance of the conductive silver paste is controlled to be less than or equal to 0.1 Ω / sq / mil to ensure the electrical connection stability of the printed circuit, the pad and other electrical elements. Preferably, the sheet resistance of the conductive silver paste is controlled to be 0.01 Ω / sq / mil to 0.07 Ω / sq / mil.

[0061] Reference Figure 4 As a second aspect of the present application, the present application provides a method for preparing a 3D printed circuit, which comprises the following steps:

[0062] S10: forming a printed circuit on a carrier using a conductive silver paste;

[0063] Specifically, in one embodiment of the present application, the printed circuit can be formed by pad printing process, that is, the conductive silver paste is first printed on a steel plate, then developed and etched, and then pad printed on the surface of the carrier, and then heat cured.

[0064] In another embodiment of the present application, the conductive silver paste can be directly inkjet printed on the surface of the carrier, and then cured to form a printed circuit, for example, using the preparation method of patent CN115332773A.

[0065] Preferably, in one embodiment of the present application, the conductive silver paste is directly inkjet printed on the surface of the carrier, and then preliminarily cured. Specifically, the preliminary curing temperature is 40°C to 60°C, and the curing time is 20 minutes to 60 minutes. By using the preliminary curing process, on the one hand, the conductive silver paste and the conductive copper paste do not need to be cured at high temperature respectively, simplifying the preparation process. On the other hand, the conductive silver paste and the conductive copper paste are cured at high temperature once, which improves the connection strength between the two and reduces the contact resistance between the two.

[0066] S20: printing one or more pads on the predetermined area of the printed circuit.

[0067] Specifically, the conductive copper paste is directly inkjet printed on the printed circuit to form a conductive connection between the printed circuit and the pad. Each pad is formed by one or more printing. Preferably, each pad is double-layer printed. After printing, high-temperature baking and curing are performed, the baking and curing temperature is 90°C to 150°C, and the baking and curing time is 10 minutes to 60 minutes.

[0068] The baking and curing temperature is mainly determined by the volatilization temperature of the organic solvent in the conductive silver paste and the conductive copper paste. In order to improve the connection strength and conductivity of the printed circuit and the pad, the baking and curing temperature of the conductive copper paste is less than or equal to the baking and curing temperature of the conductive silver paste. Preferably, the baking and curing temperature of the conductive copper paste is less than or equal to the baking and curing temperature of the conductive silver paste within 10°C. Reference Figure 5 As a third aspect of the present application, the present application provides a method for preparing a 3D printed circuit, which comprises the following steps:

[0069] S1: providing a 3D printed circuit;

[0070] Specifically, the 3D printed circuit comprises a carrier, a printed circuit printed by conductive silver paste and a solder pad formed by conductive copper paste.

[0071] S2: soldering a component to be soldered to the solder pad;

[0072] Specifically, the component to be soldered can be soldered to the solder pad by using a solder commonly used in the art, but is not limited thereto. The melting temperature of the solder used for soldering is < 400 ℃ to prevent the conductive silver paste from melting. Preferably, in an embodiment of the present application, the component to be soldered is soldered to the solder pad by using a low-temperature tin wire with a melting point of 180-220 ℃. It should be noted that when soldering by using a low-temperature tin paste, a solder joint cannot be formed on the surface of the solder pad.

[0073] S3: forming an oxidation-resistant layer on the surface of the solder pad;

[0074] Specifically, since the main component of the conductive copper paste is copper powder, the resistance of the copper powder will increase and the electrical performance will deteriorate after oxidation, so the oxidation-resistant layer is introduced. In addition, the oxidation-resistant layer can also improve the connection strength of the solder joint. Specifically, after the oxidation-resistant layer is formed, the pull-out force of the solder joint is ≥ 10 N, and more preferably 12-15 N.

[0075] Specifically, the oxidation-resistant layer can be formed by using UV glue through a dispensing process, but is not limited thereto.

[0076] Preferably, in an embodiment of the present application, the soldering method of the 3D printed circuit further comprises the following steps:

[0077] S4: testing the solder joint;

[0078] Specifically, the testing can include continuity testing and pull-out force testing, but is not limited thereto.

[0079] The continuity testing is performed by using a multimeter. The pull-out force testing is performed by using a pull-out force testing machine.

[0080] The present application will be further described in specific embodiments

[0081] Embodiment 1

[0082] A 3D printed circuit, comprising a carrier, a printed circuit printed on the carrier and two solder pads printed on the printed circuit; the printed circuit is obtained by inkjet printing of conductive silver paste, and the solder pads are obtained by inkjet printing of conductive copper paste; wherein,

[0083] The conductive silver paste is commercially available, and the model number is AlwayStone-AS6088;

[0084] The conductive copper paste comprises copper powder 60%, epoxy resin 10%, and diethyl phthalate 30%; the viscosity of the conductive copper paste is 250 dPa-s, and the resistivity is 101 x 10 -3 Ω-cm;

[0085] The content of the copper powder with a particle size less than 20 nm is 10% of the total copper powder content, the content of the copper powder with a particle size of 20-80 nm is 30% of the total copper powder content, the content of the copper powder with a particle size of 80-200 nm is 20% of the total copper powder content, and the content of the copper powder with a particle size greater than 200 nm is 40% of the total copper powder content.

[0086] Example 2

[0087] The difference from Example 1 is that the thickness of the solder pad is 100 μm.

[0088] The conductive copper paste comprises copper powder 70%, epoxy resin 6%, diethyl phthalate 22%, lecithin 1%, and triethanolamine 1%; the viscosity of the conductive copper paste is 350 dPa-s, and the resistivity is 60 x 10 -3 Ω-cm;

[0089] The content of the copper powder with a particle size less than 20 nm is 15% of the total copper powder content, the content of the copper powder with a particle size of 20-80 nm is 35% of the total copper powder content, the content of the copper powder with a particle size of 80-200 nm is 25% of the total copper powder content, and the content of the copper powder with a particle size greater than 200 nm is 25% of the total copper powder content.

[0090] Example 3

[0091] The difference from Example 1 is that the conductive copper paste comprises copper powder 80%, phenolic resin 3%, ethylene glycol dimethyl ether 10%, and dibutyl phthalate 7%; the viscosity of the conductive copper paste is 300 dPa-s, and the resistivity is 100 x 10 -3 Ω-cm;

[0092] The content of the copper powder with a particle size less than 20 nm is 5% of the total copper powder content, the content of the copper powder with a particle size of 20-80 nm is 40% of the total copper powder content, the content of the copper powder with a particle size of 80-200 nm is 30% of the total copper powder content, and the content of the copper powder with a particle size greater than 200 nm is 25% of the total copper powder content.

[0093] Example 4

[0094] The difference from Example 1 is that the conductive copper paste is commercially available, and the model number is JT5005; the viscosity of the conductive copper paste is 350 dPa-s, the copper powder content is 80%, and the resistivity is 60 x 10 -3 Ω-cm.

[0095] Example 5

[0096] Different from example 2, the content of copper powder with particle size less than 20 nm in the conductive copper paste is 40% of the total copper powder content, the content of copper powder with particle size of 20-80 nm is 20% of the total copper powder content, the content of copper powder with particle size of 80-200 nm is 10% of the total copper powder content, and the content of copper powder with particle size greater than 200 nm is 30% of the total copper powder content.

[0097] The viscosity of the conductive copper paste is 380 dPa·s, and the resistivity is 50 x 10 -3 Ω·cm.

[0098] Comparative example 1

[0099] Different from example 2, the thickness of the solder pad is 50 μm.

[0100] The 3D printed lines of examples 1-5 and comparative example 1 are tested, including soldering test, conduction test and tensile force test, 10 3D printed lines are taken for each example and comparative example for testing. Among them,

[0101] Conduction test: a multimeter is used to connect two solder pads for conduction test, and the conduction rate is calculated, the conduction rate = the number of 3D printed lines that can be conducted / the total number of 3D printed lines * 100%; for example, the number of 3D printed lines that can be conducted in example 1 is 10, and the total number is 10, so the conduction rate is 100%;

[0102] Soldering test: low-temperature solder paste is used to solder on the solder pad, and the soldering rate is calculated, the soldering rate = the number of 3D printed lines that can solder the solder paste on the solder pad / the total number of 3D printed lines * 100%;

[0103] Tensile force test: low-temperature solder paste is used to solder the lead wire on the solder pad, and a tensile force testing machine is used to pull the lead wire, and the tensile force value used when the lead wire separates from the solder pad is tested;

[0104] The test results are as follows:

[0105]

[0106]

[0107] The above is the preferred embodiment of the application, it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, these improvements and refinements are also considered to be within the scope of protection of the present application.

Claims

1. A 3D printed circuit, characterized in that, The 3D printed circuit comprises a carrier, a printed circuit printed on the carrier, and one or more solder pads printed on the printed circuit. The printed circuit is obtained by inkjet printing of conductive silver paste, and the pad is obtained by inkjet printing of conductive copper paste, the resistivity of the conductive copper paste is 50*10 -3 Ω·cm-110*10 -3 Ω·cm, and the thickness of the pad is greater than 80μm. The carrier is made of PC resin, ABS resin, PA resin, LCP resin, POM resin, PPO resin, PI resin, PP resin, PET resin, or glass fiber. The conductive copper paste comprises the following components: Copper powder 60%-80%, binder 3%-10%, organic solvent 17%-30%, and additive 0-5%. The binder is selected from one or more of ethyl cellulose, cellulose derivative, epoxy resin, phenolic resin, acrylic resin, and polyamide resin. The organic solvent is selected from one or more of terpineol, benzyl alcohol, tertiary alcohol amine, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, diethyl phthalate, butyl carbitol acetate, dibutyl phthalate, and dioctyl phthalate. The additive is selected from a surfactant and / or silane coupling agent; the silane coupling agent is selected from KH-570, KH-560, or KH-550; and the surfactant is selected from lecithin, triethanolamine, or sorbitan trioleate.

2. The 3D printed circuit of claim 1, wherein, The viscosity of the conductive copper paste is 200 dPa·s-400 dPa·s.

3. The 3D printed circuit of claim 1, wherein, The viscosity of the conductive silver paste is 80 dPa·s-200 dPa·s.

4. The 3D printed circuit of claim 1, wherein, The copper powder is nano copper powder with an average particle size of 20 nm-500 nm. The binder is selected from epoxy resin. The organic solvent is selected from diethyl phthalate.

5. The 3D printed circuit of claim 4, wherein, The content of copper powder with a particle size of 20-80 nm is 30%-40% of the total copper powder content, and the content of copper powder with a particle size of 80 nm-200 nm is 20%-30% of the total copper powder content.

6. A method for the preparation of a 3D printed circuit for the preparation of a 3D printed circuit according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: (1) forming a printed circuit on the carrier by using conductive silver paste; (2) printing one or more solder pads on the predetermined area of the printed circuit, and the process is completed.

7. The method for preparing 3D printed circuits as described in claim 6, characterized in that, In step (1), the conductive silver paste is printed on the carrier, and then preliminary solidification is performed at 40℃-60℃ for 20 min-60 min. In step (2), one or more solder pads are printed on the predetermined area of the printed circuit, and then solidification is performed at 90℃-150℃ for 10 min-60 min.

8. A method of soldering a 3D printed circuit, characterized in that, The method comprises the following steps: (i) providing the 3D printed circuit according to any one of claims 1-5; (ii) welding the to-be-welded component to the solder pad; wherein the melting temperature of the solder used for welding is <400℃; (iii) forming an oxidation-resistant layer on the surface of the solder pad.

9. The soldering method of 3D printed circuit according to claim 8, wherein, In step (ii), the to-be-welded component is welded to the solder pad by using low-temperature tin wire; wherein the melting point of the low-temperature tin wire is 180℃-220℃.

10. Application of the 3D printed circuit according to any one of claims 1-5 as an antenna.

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