Composite conductive ink, pressure-sensitive resistor and pressure-sensitive circuit assembly

Abstract

The invention provides composite conductive ink which comprises the following components in percentage by mass: 20%-25% of conductive filler, 10%-20% of oleophylic polymer, 10%-20% of hydrophilic polymer and 35%-40% of solvent, the mass fraction of the conductive filler is 20%-25%, the mass fraction of the oleophylic polymer is 10%-20%, and the mass fraction of the solvent is 35%-40%. An interface is formed between the hydrophilic polymer and the oleophylic polymer, and the conductive filler is orderly distributed on the interface. The piezoresistor manufactured by the composite conductive ink provided by the invention has better sensitivity. In addition, the invention also provides a voltage sensing resistor and a voltage sensing circuit assembly.

Description

Technical Field

[0001] The present application belongs to the field of conductive inks, and in particular, relates to a composite conductive ink and a pressure-sensitive circuit assembly. Background Art

[0002] Carbon conductive ink is widely used in the field of making piezoresistors. Generally, the components of carbon conductive ink mainly include carbon powder particles and binders. The binder adheres the conductive carbon powder particles together, causing the carbon powder particles to be close to each other and achieve electrical conduction, thereby constructing a piezoresistor element. However, poor contact between carbon powder particles can easily lead to poor sensitivity of the piezoresistors and limited sensing range. Summary of the invention

[0003] In order to solve the above deficiencies in the prior art, the present application provides a composite conductive ink.

[0004] In addition, the present application also provides a pressure-sensitive resistor.

[0005] In addition, the present application also provides a pressure-sensing circuit component.

[0006] A composite conductive ink comprises a conductive filler, a hydrophilic polymer, an oleophilic polymer and a solvent, wherein the mass fraction of the conductive filler is 20% to 25%, the mass fraction of the oleophilic polymer is 10% to 20%, the mass fraction of the hydrophilic polymer is 10% to 20%, and the mass fraction of the solvent is 35% to 40%, wherein an interface is formed between the hydrophilic polymer and the oleophilic polymer, and the conductive filler is orderly distributed at the interface.

[0007] In some possible embodiments, an auxiliary agent is further included, and the mass fraction of the auxiliary agent is 10% to 15%.

[0008] In some possible embodiments, the auxiliary agent includes at least one of polysiloxane, octanol polyoxyethylene ether, octanoic acid polyoxyethylene ether, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sodium octyl sulfonate, and sodium octyl sulfonate.

[0009] In some possible embodiments, the conductive filler is carbon black.

[0010] In some possible embodiments, the hydrophilic polymer includes at least one of dimethylaminoethyl methacrylate, polyacrylic acid, polyvinyl alcohol, polyacrylamide, gelatin, chitosan, polyacrylamine, gelatin methacrylate, chitosan sulfate, polypropylene imine, and polyvinyl pyrrolidone.

[0011] In some possible embodiments, the oleophilic polymer includes at least one of glycidyl methacrylate, polystyrene, polypropylene, polybutylene terephthalate, polyetherketone, polyethylene, polyacrylate, polyamide, polycarbonate, polylactic acid and polyolefin.

[0012] In some possible embodiments, the solvent includes at least one of 2-(2-ethoxyethoxy)ethanol, acetone, ethyl acetate, ketone, xylene, toluene, chloroform, acetic acid acetone, ethyl acetate ketone, n-butanol and ethylene glycol.

[0013] A pressure-sensitive resistor is formed by removing the solvent in the composite conductive ink as described above.

[0014] A pressure-sensitive circuit assembly includes a circuit substrate, a plurality of the above-mentioned pressure-sensitive resistors, and a plurality of connecting wires. The circuit substrate includes a first circuit layer, and the first circuit layer has a wire groove. The pressure-sensitive resistor is arranged in the wire groove. The plurality of connecting wires connect the first circuit layer and the plurality of the pressure-sensitive resistors.

[0015] In some possible embodiments, the circuit substrate further includes a base material layer, a second circuit layer and a conductor, wherein the first circuit layer and the second circuit layer are respectively arranged on opposite sides of the base material layer, and the conductor is arranged in the base material layer and electrically conducts the first circuit layer and the second circuit layer.

[0016] In the composite conductive ink provided by the present application, there is a clear interface between the hydrophilic polymer and the lipophilic polymer, and the conductive filler is orderly distributed on this interface. This design makes full use of the difference in interfacial tension between the conductive filler and the hydrophilic polymer, and the lipophilic polymer and the conductive filler form a microdomain through intermolecular forces. Every two adjacent microdomains are in contact with each other, thereby forming a lateral conduction circuit. After baking, the microdomain is not only stable, but also provides an efficient electron transmission path, thereby enhancing the sensitivity of the composite conductive ink. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A microscopic schematic diagram of a pressure-sensitive resistor provided in an embodiment of the present application.

[0018] Figure 2 A schematic cross-sectional view of a circuit substrate provided in accordance with an embodiment of the present application.

[0019] Figure 3 for Figure 2 The cross-sectional view of the circuit substrate shown is a schematic diagram after a pressure-sensitive resistor is set.

[0020] Figure 4 A schematic cross-sectional view of a pressure sensing circuit assembly provided in accordance with an embodiment of the present application.

[0021] Main component symbols

[0022] Circuit board 10

[0023] Base material layer 11

[0024] First circuit layer 12

[0025] Wire trough 121

[0026] The second circuit layer 13

[0027] Conductor 14

[0028] First protective layer 15

[0029] The first pressure-sensing resistor 20

[0030] Connection line 21

[0031] Second protective layer 22

[0032] The first pressure sensing circuit component 30

[0033] Conductive filler A

[0034] Hydrophilic polymer B

[0035] Oleophilic polymer C

[0036] Micro Domain X

[0037] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0039] The present application provides a composite conductive ink that can be used to manufacture a pressure-sensitive resistor. The composite conductive ink includes a conductive filler A, a hydrophilic polymer B, a lipophilic polymer C, and a solvent. The mass fraction of the conductive filler A is 20% to 25%, the mass fraction of the lipophilic polymer C is 10% to 20%, the mass fraction of the hydrophilic polymer B is 10% to 25%, and the mass fraction of the solvent is 30% to 60%. An interface is formed between the hydrophilic polymer B and the lipophilic polymer C, and the conductive filler A is distributed at the interface.

[0040] There is a clear interface between the hydrophilic polymer B and the lipophilic polymer C, and the conductive filler A is orderly distributed on this interface. This design makes full use of the difference in interfacial tension between the conductive filler A and the hydrophilic polymer B, thereby forming a local domain structure (LDS). In this structure, the lipophilic polymer C and the conductive filler A interact through intermolecular forces, such as van der Waals forces, so that they form a microdomain X together. More specifically, every two adjacent microdomains X are in contact with each other, thereby forming a lateral conduction circuit.

[0041] This composite conductive ink is unique in that: Figure 1 After baking, multiple macroscopic microdomains X appear on the surface, the diameter of the microdomain X is between 25 and 70 μm, and multiple conductive fillers A are orderly distributed at the edge of each microdomain X, and every two adjacent microdomains X are electrically connected through the orderly distributed conductive fillers A. These microdomains X are not only stable, but also provide an efficient electron transmission path, thereby enhancing the sensitivity of the composite conductive ink. Compared with the use of sheet-like carbon materials to form a lateral conduction circuit, this design has higher sensitivity and provides more reliable conductive performance for various applications.

[0042] Furthermore, the composite conductive ink further comprises an additive, the mass fraction of which is 10% to 15%. It can affect the interface properties and dispersion properties of the composite conductive ink. The additive comprises at least one of polysiloxane, a defoamer, a nonionic surfactant, an anionic surfactant, a cationic surfactant and a zwitterionic surfactant. Among them, the nonionic surfactant includes octyl polyethylene glycol ether, octyl thoxyethanol, fatty alcohol ethoxylate; the anionic surfactant includes fatty alcohol ethoxylate, sodium octyl sulfate, sodium octyl sulfate; the cationic surfactant includes cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide and sodium octyl sulfate; the zwitterionic surfactant includes cetyl-N-methyl-N-(2-hydroxyethyl)-2-oxyethyl ammonium. Preferably, the auxiliary agent is polysiloxane. It can be understood that in other embodiments of the present application, the auxiliary agent can also be a defoamer, a leveling agent, etc., wherein the defoamer includes polyether-modified silicone or mineral oil / wax / silicone, etc., and the leveling agent includes acrylate homopolymer, etc.

[0043] Further, the conductive filler A includes at least one of carbon black, silver powder, conductive polymers, carbon nanotubes, gold powder, copper powder, aluminum powder, conductive carbon fibers, and conductive carbon fibers. Among them, the conductive polymer includes polyacetylene and polyaniline. Preferably, the conductive filler A is spherical carbon black. The lipophilic polymer C has a strong interaction with the spherical carbon black, and the spherical carbon black is highly orderly arranged on the surface of the lipophilic polymer C, which is conducive to forming a stable conductive structure.

[0044] Further, the hydrophilic polymer B is a polymer containing hydrophilic functional groups such as acid groups and amine groups, and can be specifically at least one of dimethylaminoethyl methacrylate ((dimethylamino)ethyl methacrylate, pDMAEMA), polyacrylic acid, polyvinyl alcohol, polyacrylamide, gelatin, chitosan, polypropylene amine, gelatin methacrylate, chitosan sulfate, polyethyleneimine, and polyvinylpyrrolidone (PVP). In this embodiment, the hydrophilic polymer B is dimethylaminoethyl methacrylate ((dimethylamino)ethylmethacrylate, pDMAEMA).

[0045] Further, the lipophilic polymer C comprises a long chain structure and a conjugated ring structure, and specifically can be at least one of poly(glycidyl methacrylate) (PGMA), polystyrene, polypropylene, polybutylene terephthalate (PBT), polyetherketone (PEK), polyethylene, polypropylene Acrylate, polyamide, polycarbonate, polylactic acid (PLA) and polyolefin. In the present embodiment, the lipophilic polymer C is poly(glycidyl methacrylate) (PGMA).

[0046] Further, the solvent includes at least one of acetone, ethyl acetate, methyl ethyl ketone (MEK), xylene, toluene, chloroform, acetic acid acetone, methyl isobutyl ketone (MIBK), n-butanol, ethylene glycol and 2-(2-ethoxyethoxy)ethanol (diethylene glycol monoethylether, DEGEE). In this embodiment, the solvent is 2-(2-ethoxyethoxy)ethanol (diethylene glycol monoethyl ether, DEGEE).

[0047] The following is a combination of four specific embodiments and a comparative example to manufacture a pressure-sensitive circuit assembly to further illustrate the composite ink.

[0048] Embodiment 1 provides a method for manufacturing a first pressure-sensing circuit assembly 30, which specifically includes the following steps:

[0049] S1: Please see Figure 2, a circuit substrate 10 is provided, the circuit substrate 10 includes a base material layer 11, a first circuit layer 12 and a second circuit layer 13 disposed on opposite sides of the base material layer 11, a conductive body 14 disposed in the base material layer 11 and connecting the first circuit layer 12 and the second circuit layer 13, and a first protective layer 15 disposed on one side of the second circuit layer 13. The first circuit layer 12 has a plurality of wire grooves 121, and a portion of the base material layer 11 is exposed at the bottom of the wire grooves 121.

[0050] S2: See Figure 3 , a first composite conductive ink is arranged in the plurality of the wire grooves 121, and the first composite conductive ink is dried to remove the solvent in the first composite conductive ink, so as to form a plurality of first pressure-sensitive resistors 20. The first composite conductive ink comprises: carbon black, with a mass fraction of 20%, glycidyl methacrylate, with a mass fraction of 20%, dimethylaminoethyl methacrylate, with a mass fraction of 10%, polysiloxane, with a mass fraction of 10%, and 2-(2-ethoxyethoxy)ethanol, with a mass fraction of 40%.

[0051] S3: See Figure 4 , a connecting line 21 is provided on the first circuit layer 12, and the connecting line 21 connects the first pressure-sensitive resistor 20 and the first circuit layer 12. The first pressure-sensitive resistor 20 is connected to the first circuit layer 12 through the connecting line 21. Under the action of external force, the resistance change of the first pressure-sensitive resistor 20 can be measured, and the sensitivity value of the first pressure-sensitive resistor 20 is calculated to be 6.2 according to the resistance change and the magnitude of the external force.

[0052] Specifically, in step S3, the steps of testing and calculating the sensitivity value are as follows:

[0053] S31: Measure and record the length (100 mm) and resistance value of the first pressure-sensitive resistor 20 before the test.

[0054] S32: Welding a wire to the first voltage-sensing resistor 20, and connecting the wire to an ohmmeter (four-wire).

[0055] The upper and lower clamps are clamped at the product marking line position, the zero point is set at this position, the stroke is set, the tensile machine is started to stretch to the set stroke according to the stroke speed, the resistance value is read and recorded, the tensile machine returns to the zero starting position, and performs a 1% elongation stroke.

[0056] S33: Measure and record the resistance value after each stroke test.

[0057] Calculation formula: Sensitivity value = ((resistance after test - resistance before test) / resistance before test) / (length after test - length before test) / length before test), for example: if the resistance after test is 4.25KΩ, the resistance before test is 4.0KΩ, the length before stretching is 100mm, and the length after stretching is 101mm, then the sensitivity value = ((4.25-4.0) / 4.0) / (101-100) / 100) = 6.2.

[0058] S4: See Figure 4 A second protective layer 22 is disposed on the connecting line 21 , and the second protective layer 22 covers the first circuit layer 12 , the first pressure-sensing resistor 20 and the connecting line 21 , thereby obtaining the first pressure-sensing circuit component 30 .

[0059] Embodiment 2 provides a method for manufacturing a second pressure-sensitive circuit component (not shown), which is different from Embodiment 1 in that the second composite conductive ink used in step S2 of Embodiment 2 includes: carbon black, with a mass fraction of 20%, glycidyl methacrylate, with a mass fraction of 20%, dimethylaminoethyl methacrylate, with a mass fraction of 15%, polysiloxane, with a mass fraction of 15%, and 2-(2-ethoxyethoxy)ethanol, with a mass fraction of 40%. At the same time, under the same test conditions as Embodiment 1, the sensitivity of the second pressure-sensitive resistor (not shown) is 5.3.

[0060] Embodiment 3 provides a method for manufacturing a third pressure-sensitive circuit component (not marked), which is different from Embodiment 1 in that the third composite conductive ink used in step S2 of Embodiment 3 includes: carbon black, with a mass fraction of 20%, glycidyl methacrylate, with a mass fraction of 10%, dimethylaminoethyl methacrylate, with a mass fraction of 20%, polysiloxane, with a mass fraction of 10%, and 2-(2-ethoxyethoxy)ethanol, with a mass fraction of 40%. At the same time, under the same test conditions as Embodiment 1, the sensitivity of the third pressure-sensitive resistor (not marked) is 3.5.

[0061] Embodiment 4 provides a method for manufacturing a fourth pressure-sensitive circuit component (not shown), which is different from Embodiment 1 in that the fourth composite conductive ink used in step S2 of Embodiment 4 includes: carbon black, with a mass fraction of 25%, glycidyl methacrylate, with a mass fraction of 10%, dimethylaminoethyl methacrylate, with a mass fraction of 20%, polysiloxane, with a mass fraction of 10%, and 2-(2-ethoxyethoxy)ethanol, with a mass fraction of 35%. At the same time, under the same test conditions as Embodiment 1, the sensitivity of the fourth pressure-sensitive resistor (not shown) is 3.3.

[0062] Comparative Example 1 provides a method for manufacturing a fourth pressure-sensitive circuit component (not marked), which is different from Example 1 in that the fourth composite conductive ink used in step S2 of Example 4 includes: multilayer graphene, with a mass fraction of 25%, glycidyl methacrylate, with a mass fraction of 0%, dimethylaminoethyl methacrylate, with a mass fraction of 25%, polysiloxane, with a mass fraction of 10%, and 2-(2-ethoxyethoxy)ethanol, with a mass fraction of 40%. At the same time, under the same test conditions as Example 1, the sensitivity of the fourth pressure-sensitive resistor (not marked) is 2.5.

[0063] The following table summarizes the components of the composite conductive inks of four embodiments and one comparative example according to the sensitivity of the piezoresistance.

[0064]

[0065] It can be found that the sensitivity value of the piezoresistors in any of the four embodiments provided in the present application is greater than that of the piezoresistors in comparative example 1. In other words, the highly ordered arrangement of carbon black at the interface between the lipophilic polymer C and the hydrophilic polymer B can effectively improve the sensitivity of the piezoresistors.

[0066] See also Figure 4 The first embodiment of the present application further provides a first pressure-sensing circuit assembly 30, which includes a circuit substrate 10, a plurality of first pressure-sensing resistors 20, and a plurality of connecting wires 21. The circuit substrate 10 includes a substrate layer 11, a first circuit layer 12 and a second circuit layer 13 disposed on opposite sides of the substrate layer 11, a conductive body 14 disposed in the substrate layer 11 and connecting the first circuit layer 12 and the second circuit layer 13, and a first protective layer 15 disposed on one side of the second circuit layer 13, the first circuit layer 12 has a plurality of wire grooves 121, and part of the substrate layer 11 is exposed at the bottom of the wire grooves 121. The plurality of first pressure-sensing resistors 20 are disposed in the wire grooves 121. The plurality of connecting wires 21 connect the first circuit layer 12 and the plurality of first pressure-sensing resistors 20 to form a Wheatstone bridge structure.

[0067] See also Figure 4 In this embodiment, the first pressure-sensing circuit component 30 further includes a second protective layer 22 , and the second protective layer 22 covers the first circuit layer 12 , the first pressure-sensing resistor 20 and the connecting line 21 .

[0068] The above description is only an optimized specific implementation of the present application, but it cannot be limited to this implementation in the actual application process. For ordinary technicians in this field, other variations and changes made according to the technical concept of the present application should all fall within the protection scope of the present application.

Claims

1. A composite conductive ink, characterized in that: The invention comprises a conductive filler, a hydrophilic polymer, a lipophilic polymer and a solvent, wherein the mass fraction of the conductive filler is 20% to 25%, the mass fraction of the lipophilic polymer is 10% to 20%, the mass fraction of the hydrophilic polymer is 10% to 20%, and the mass fraction of the solvent is 35% to 40%, wherein an interface is formed between the hydrophilic polymer and the lipophilic polymer, and the conductive filler is orderly distributed at the interface.

2. The composite conductive ink according to claim 1, characterized in that: The invention also comprises an auxiliary agent, wherein the mass fraction of the auxiliary agent is 10% to 15%.

3. The composite conductive ink according to claim 2, characterized in that: The auxiliary agent includes at least one of polysiloxane, octanol polyoxyethylene ether, octanoic acid polyoxyethylene ether, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sodium octyl sulfonate, and sodium octyl sulfonate.

4. The composite conductive ink according to claim 1, characterized in that: The conductive filler is carbon black.

5. The composite conductive ink according to claim 1, characterized in that: The hydrophilic polymer includes at least one of dimethylaminoethyl methacrylate, polyacrylic acid, polyvinyl alcohol, polyacrylamide, gelatin, chitosan, polyacrylamine, gelatin methacrylate, chitosan sulfate, polypropylene imine, and polyvinyl pyrrolidone.

6. The composite conductive ink according to claim 1, characterized in that: The oleophilic polymer includes at least one of glycidyl methacrylate, polystyrene, polypropylene, polybutylene terephthalate, polyether ketone, polyethylene, polyacrylate, polyamide, polycarbonate, polylactic acid and polyolefin.

7. The composite conductive ink according to claim 1, characterized in that: The solvent includes at least one of 2-(2-ethoxyethoxy)ethanol, acetone, ethyl acetate, ketone, xylene, toluene, chloroform, acetic acid acetone, ethyl acetate ketone, n-butanol and ethylene glycol.

8. A pressure-sensitive resistor, characterized in that: The voltage-sensitive resistor is formed by removing the solvent in the composite conductive ink according to any one of claims 1 to 7.

9. A pressure-sensitive circuit assembly, characterized in that: include: A circuit substrate, the circuit substrate comprising a first circuit layer, the first circuit layer having a wire groove, The pressure-sensing resistor according to claim 8, wherein the pressure-sensing resistor is arranged in the wire slot, and A plurality of connecting wires are provided, wherein the plurality of connecting wires connect the first circuit layer and the plurality of pressure-sensing resistors.

10. The pressure sensing circuit assembly according to claim 9, wherein: The circuit substrate further includes a base material layer, a second circuit layer and a conductor. The first circuit layer and the second circuit layer are respectively arranged on opposite sides of the base material layer. The conductor is arranged on the base material layer and electrically connects the first circuit layer and the second circuit layer.

Images