Manufacturing method of wire with terminal

Abstract

The invention relates to the field of electronic and electrical connection, and discloses a manufacturing method of a wire with a terminal, which comprises the following steps: S1, preparing a conductive adhesive: mixing epoxy resin, silver powder, copper nanoparticles, carbon nanotubes, a curing agent, a toughening agent, a dispersing agent and a defoaming agent according to a ratio to obtain the conductive adhesive; the conductive adhesive is obtained through premixing, nano-particle dispersion, step-by-step addition of silver powder, defoaming treatment, addition of a flexibilizer and secondary dispersion. S2, peeling, cleaning, coarsening and activating the wire and the terminal; s3, coating a conductive adhesive on a connection area of the conductor of the electric wire and the terminal; s4, inserting the wire into the terminal, and applying pressure for bonding; and S5, after the connecting piece is preliminarily cured, the connecting piece is completely cured. Efficient connection between the wire and the terminal is achieved through the conductive adhesive, mechanical damage caused by traditional crimping is avoided, the conductivity and mechanical strength are improved, adaptability is high, and reliable electrical connection can be provided in a severe environment.

Description

Technical Field

[0001] The invention relates to the technical field of electronic and electrical connection, in particular to a method for manufacturing an electric wire with a terminal. Background Art

[0002] In the field of electronics and electrical, wires with terminals are widely used in various devices and systems, playing a key role in the transmission of electrical energy and signals. Traditionally, the connection between wires and terminals is mainly achieved by mechanical crimping or welding. These traditional methods rely on mechanical force to firmly combine the terminal with the conductor part of the wire to ensure the stability of the electrical connection. However, although these methods have been widely used, there are still many problems and limitations in practical applications, which restrict their reliability and life in certain application scenarios.

[0003] Mechanical crimping usually requires applying a large amount of mechanical pressure to firmly press the terminal and the wire. Although this method is relatively simple and can meet most connection requirements, it often faces the risk of mechanical fatigue, looseness and poor contact during long-term use. Mechanical crimping connections are easily affected by external vibrations, mechanical stress or thermal stress. Over time, the connection part may become loose or microscopically fractured, resulting in reduced conductivity or even failure. In addition, excessive crimping force can also cause irreversible mechanical damage to the conductor and insulation layer of the wire, reducing the durability of the entire connection, especially when used under high-frequency vibration or complex environmental conditions.

[0004] Welding is used as an alternative in some cases. Although welding can provide higher connection strength, the welding process requires high temperatures, which may not be suitable for some sensitive components or materials. In addition, the welding process is easily affected by operating conditions, and the quality of the solder joints may be uneven, resulting in the inability to ensure long-term connection stability. The high temperature required for welding may also damage the insulation materials of the cables and terminals, shortening their lifespan.

[0005] Another major limitation of traditional crimping and welding methods is that they perform poorly in harsh environments (such as high temperature, humidity, and corrosive environments). In such environments, the connection points are prone to oxidation and corrosion, which increases the contact resistance, reduces the conductivity, and even causes the connection to fail. Therefore, traditional crimping and welding processes have obvious shortcomings in application scenarios that require high environmental adaptability, and new solutions are urgently needed to overcome these technical bottlenecks. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for manufacturing a wire with a terminal, which solves the problems of mechanical damage, poor contact and poor environmental adaptability existing in the connection of the traditional wire with a terminal.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for manufacturing a wire with a terminal, comprising the following steps:

[0008] S1. preparing a conductive adhesive: mixing epoxy resin, silver powder, copper nanoparticles, carbon nanotubes, a curing agent, a toughening agent, a dispersant and a defoaming agent in proportion, and obtaining a conductive adhesive through premixing, nanoparticle dispersion, gradual addition of silver powder, defoaming treatment, toughening agent addition and secondary dispersion;

[0009] S2. Surface pretreatment: stripping, surface cleaning, surface roughening and activation of wires and terminals;

[0010] S3, applying a conductive adhesive: applying a conductive adhesive to a connection area between a conductor and a terminal of the wire;

[0011] S4. Assembly of terminals and wires: insert the wires into the terminals and apply pressure for bonding;

[0012] S5. Curing: Place the connector in an environment of 60-80℃ for preliminary curing for 1-2 hours, and then fully cure it in an environment of 100-120℃ for 2-3 hours.

[0013] The present invention provides a method for manufacturing a wire with a terminal, which has the following beneficial effects:

[0014] 1. The present invention uses a highly conductive adhesive to replace the traditional mechanical crimping method, and forms a uniform and dense conductive network through the synergistic effect of silver powder, copper nanoparticles and carbon nanotubes. This design greatly reduces the contact resistance, ensures that the electrical connection between the wire and the terminal is more stable and reliable, and avoids the poor contact problem caused by mechanical fatigue in the traditional crimping method.

[0015] 2. The present invention uses a conductive adhesive to bond the wire to the terminal without mechanical extrusion, thus avoiding mechanical damage to the wire core and the terminal in the traditional crimping method. This improvement effectively extends the service life of the wire, and is particularly suitable for applications in precision equipment or complex environments.

[0016] 3. After curing, the conductive adhesive of the present invention has excellent resistance to environmental stress, especially showing excellent stability under harsh conditions such as high temperature, humidity and vibration. The cured adhesive provides strong resistance to corrosion, oxidation and mechanical fatigue, significantly improving the service life of the wire with terminals in complex environments.

[0017] 4. The present invention uses a two-stage curing process (initial curing and complete curing) to ensure that the adhesive can be fully cross-linked to form a high-strength three-dimensional network structure. This curing process ensures the mechanical strength and stability of the bonding interface, allowing the conductive adhesive to effectively withstand mechanical and thermal stresses, thereby improving the overall reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Please see attached Figure 1 The embodiment of the present invention provides a method for manufacturing a wire with a terminal, which focuses on using a conductive adhesive to replace the traditional mechanical crimping technology, and ensures that an efficient and stable conductive path is formed between the wire and the terminal through chemical bonding.

[0021] The core principle of conductive adhesives is to form a uniform and continuous conductive network in the epoxy resin matrix through highly conductive fillers (such as silver powder, copper nanoparticles and carbon nanotubes). Epoxy resin, as a matrix material, provides good mechanical bonding properties and environmental stability. Through the reaction and cross-linking of the curing agent and epoxy resin, a stable three-dimensional network structure is generated, giving the adhesive excellent mechanical strength and durability.

[0022] Specifically, silver powder, as the main body of conductive filler, forms a large number of conductive paths inside the material, ensuring low resistance at the bonding interface; copper nanoparticles, due to their small size advantage, fill the tiny gaps between the silver powders, further reducing the resistance of the overall conductive adhesive; carbon nanotubes, through their high aspect ratio and flexible network structure, improve the tensile strength and durability of the adhesive. The overall system forms a dense conductive path through the distribution and solidification of these nanoparticles, effectively improving the conductivity and mechanical strength of the bonding area.

[0023] During the synthesis process, the introduction of toughening agents increases the flexibility of the adhesive, making it less prone to brittle cracking after curing, thereby adapting to stress changes such as mechanical vibration and thermal expansion. In addition, dispersants and defoamers ensure the uniform distribution of conductive fillers in the matrix, eliminate air microbubbles, and improve the integrity and electrical stability of the bonding interface.

[0024] S1. Raw material selection:

[0025] Specifically, the conductive adhesive comprises epoxy resin, silver powder, copper nanoparticles, carbon nanotubes, a curing agent, a toughening agent, a dispersant and a defoaming agent. The proportions of the components and their functions are as follows:

[0026] Epoxy resin (40-50 wt%): As a matrix material, epoxy resin provides high adhesion, chemical stability and good environmental resistance.

[0027] Silver powder (20-30wt%): Main conductive filler, ensuring the conductivity of the bonding area. Silver powder has high conductivity and can form an efficient current path after filling.

[0028] Copper nanoparticles (5-10 wt%): auxiliary conductive filler, used to fill the gaps between silver powders to further reduce the overall resistance.

[0029] Carbon nanotubes (2-5wt%): Improve the mechanical strength and electrical conductivity of the adhesive. They have a high aspect ratio and excellent electrical conductivity, forming an efficient conductive network.

[0030] Curing agent (10-15wt%): Promotes the curing reaction of epoxy resin, forms a stable cross-linking network, and gives the material excellent mechanical and thermal properties.

[0031] Toughening agent (2-5wt%): increases the flexibility of the adhesive, avoids brittle failure of the material after curing, and improves its durability and impact resistance.

[0032] Dispersant (1-2 wt%): Improve the dispersibility of silver powder, copper nanoparticles and carbon nanotubes in the resin and avoid particle agglomeration.

[0033] Defoamer (0.5-1wt%): eliminates bubbles during stirring and coating to ensure the integrity of the conductive path.

[0034] The preparation steps of the conductive adhesive include:

[0035] 1. Premixing: First, weigh the epoxy resin and curing agent in proportion and place them in a stirring container for preliminary stirring. The stirring speed is controlled at 300-500rpm for 10-15 minutes to ensure that the curing agent and epoxy resin are initially mixed.

[0036] 2. Surface treatment of copper nanoparticles: To improve the dispersibility of copper nanoparticles, the surface of copper nanoparticles is first modified with a modifier, such as a silane coupling agent, to increase its compatibility with epoxy resin.

[0037] 3. Nanoparticle dispersion: Use high shear dispersion equipment to add copper nanoparticles and carbon nanotubes to the mixture separately. The stirring speed is 1000-1500rpm, and the dispersion time is controlled at 30-45 minutes to ensure that the nanoparticles are evenly distributed in the resin matrix. At the same time, ultrasonic vibration equipment is used with the vibration frequency set to 20-30kHz and the vibration time set to 10-15 minutes to further disperse the nanoparticles.

[0038] 4. Gradually add silver powder: After the nanoparticles are evenly dispersed, add the pre-dried silver powder (dried at 100-120°C for 30-50 minutes) in batches. To ensure that the silver powder is fully in contact with the epoxy resin matrix, use a segmented stirring method, stirring for 5-10 minutes each time, and the stirring speed is controlled at 800-1200rpm.

[0039] 5. Defoaming treatment: After stirring, place the mixture in a vacuum degassing machine, set the degassing pressure at -0.08 to -0.1MPa, and control the degassing time at 10-20 minutes to remove bubbles during the mixing process.

[0040] 6. Addition of toughening agent: After degassing, add toughening agent to increase the flexibility of the material. The stirring speed is controlled at 500-700rpm and the stirring time is 10-15 minutes.

[0041] 7. Secondary dispersion: Finally, a double-roll grinding device is used to disperse the conductive adhesive for a secondary time, with the pressure set at 200-300N and the grinding time at 10-15 minutes to ensure that all ingredients are evenly distributed and the fluidity and dispersibility of the adhesive are in the best state.

[0042] S2. Surface pretreatment

[0043] The bonding performance of conductive adhesives depends largely on the cleanliness and activity of the wire and terminal surfaces. To improve the bonding strength, the wire and terminal surface must be pretreated. The following steps are included:

[0044] Wire stripping: Use automatic wire stripping equipment to remove 10-15mm of insulation from the end of the wire, ensuring that the conductor surface is completely exposed.

[0045] Surface cleaning: Use isopropyl alcohol to perform ultrasonic cleaning to remove surface oil and oxide layer. The cleaning time is controlled within 5-10 minutes, followed by drying in an oven at 60-80℃ for 10 minutes to ensure that there is no residual moisture on the surface.

[0046] Surface Roughening: Use 300-500 grit sandpaper to lightly sand the exposed conductor surfaces of the wires and terminals to increase the adhesion area for the adhesive.

[0047] Surface activation: The polished surface is activated by oxygen plasma equipment, the plasma power is set to 150-200W, and the processing time is 20-30 seconds.

[0048] After surface pretreatment is completed, the conductive adhesive is evenly applied to the conductor and terminal connection areas of the wire.

[0049] Glue dispensing: Use an automatic glue dispensing machine for coating, with the coating thickness controlled at 100-200μm and the glue dispensing speed at 1-3mm / s to ensure uniform distribution of the adhesive. Depending on the complexity of the connection between the wire and the terminal, the glue dispensing amount can be controlled by a micro-adjuster to ensure the accuracy of the coating.

[0050] S3. Assembly of terminals and wires

[0051] After coating is completed, the terminal and the wire are precisely assembled.

[0052] Positioning assembly: Use a clamp to fix the wire and the terminal to ensure that the position does not shift before the adhesive cures. This step requires precise alignment of the wire and the terminal.

[0053] Apply pressure: Apply a slight pressure of 10-20N on the terminal and wire connection to ensure uniform penetration of the adhesive. The pressure duration is controlled at 3-5 minutes to ensure full bonding of the bonding interface.

[0054] S4, curing step

[0055] Curing is a critical step to ensure that the conductive adhesive forms a strong structure.

[0056] Initial curing: Place the connector in a 60-80°C environment for initial curing for 1-2 hours to ensure that the epoxy resin and curing agent undergo initial cross-linking reaction.

[0057] Fully curing: Raise the temperature to 100-120°C and continue curing for 2-3 hours to ensure that the conductive adhesive is fully cross-linked to form a stable conductive path and a strong bonding structure.

[0058] Cooling treatment: After curing is completed, cool naturally to room temperature. The cooling time is controlled within 30-60 minutes to avoid cracks or deformation of the adhesive due to thermal shock.

[0059] This manufacturing method achieves efficient conductive connection between wires and terminals through a scientifically designed conductive adhesive formula and precise preparation and processing technology. It has significant mechanical strength, conductive properties and environmental resistance, and is suitable for various high-performance application scenarios.

[0060] In order to better understand the present invention, the above method is described in detail below in conjunction with specific embodiments.

[0061] Example 1: Method for manufacturing electric wire with terminal for automobile wiring harness

[0062] S1. Preparation of conductive adhesive

[0063] Raw material ratio:

[0064] Epoxy resin: 45wt%, silver powder: 25wt%, copper nanoparticles: 8wt%, carbon nanotubes: 3wt%, curing agent: 12wt%, toughening agent: 3wt%, dispersant: 1wt%, defoaming agent: 1wt%

[0065] Preparation steps:

[0066] 1. Stir the epoxy resin and curing agent in proportion at 300 rpm for 15 minutes.

[0067] 2. The copper nanoparticles and carbon nanotubes were stirred at 1000 rpm for 40 minutes and treated with 20 kHz ultrasonic vibration for 15 minutes.

[0068] 3. Add silver powder in stages, 5 minutes each time, with a stirring speed of 1200 rpm.

[0069] 4. Use vacuum degassing equipment for degassing, vacuum degree -0.1MPa, time 15 minutes.

[0070] 5. Add toughening agent and stir at low speed of 700 rpm for 10 minutes.

[0071] 6. The secondary dispersion uses a double-roll grinding device with a pressure of 250N and a time of 15 minutes.

[0072] S2. Surface pretreatment

[0073] Use an automatic wire stripping machine to strip 12mm.

[0074] Clean the terminals and wires, ultrasonically clean them with isopropyl alcohol, and dry them at 70°C after 5 minutes.

[0075] The conductor surface was sanded with 400 grit sandpaper and then treated with oxygen plasma at 150 W for 25 seconds.

[0076] S3. Coating of conductive adhesive

[0077] Use an automatic dispensing machine to apply the adhesive to the connection between the terminal and the wire, with a coating thickness of 150 μm and a dispensing speed of 2 mm / s.

[0078] S4. Assembly of terminals and wires

[0079] Insert the wire into the terminal using the positioning fixture, ensuring alignment. Apply 15N of pressure for 4 minutes.

[0080] S5. Curing

[0081] Initial curing was at 70°C for 1 hour.

[0082] Completely cure at 110°C for 2.5 hours and cool naturally to room temperature, cooling time 45 minutes.

[0083] Example 2: Method for manufacturing high-durability electric wire with terminal for aerospace use

[0084] S1. Preparation of conductive adhesive

[0085] Raw material ratio:

[0086] Epoxy resin: 42wt%, silver powder: 28wt%, copper nanoparticles: 6wt%, carbon nanotubes: 4wt%, curing agent: 12wt%, toughening agent: 3wt%, dispersant: 1.5wt%, defoaming agent: 0.5wt%

[0087] Preparation steps:

[0088] 1. Using a high shear mixer, stir the epoxy resin and curing agent at 400 rpm for 10 minutes.

[0089] 2. The copper nanoparticles were stirred at 1200 rpm for 30 minutes and simultaneously treated with 25 kHz ultrasound for 10 minutes.

[0090] 3. Add silver powder in batches, control the stirring speed at 1000rpm, and stir for 6 minutes for each batch.

[0091] 4. Use vacuum degassing treatment, pressure -0.09MPa, time 10 minutes.

[0092] 5. The toughening agent was stirred at 500 rpm for 12 minutes.

[0093] 6. Grind using a double-roll grinder with a pressure of 280 N and a time of 12 minutes.

[0094] S2. Surface pretreatment

[0095] The stripping length is 15mm.

[0096] After cleaning the wires and terminals with isopropyl alcohol, dry them at 70°C for 10 minutes.

[0097] After the surface was polished with 500-grit sandpaper, oxygen plasma treatment was used with a power of 180 W for 30 seconds.

[0098] S3. Coating of conductive adhesive

[0099] The coating thickness is 180μm and the dispensing speed is 2.5mm / s.

[0100] S4. Assembly of terminals and wires

[0101] After inserting the wire into the terminal using the positioning fixture, apply 20N pressure for 5 minutes.

[0102] S5. Curing

[0103] The initial curing temperature is 65°C and the time is 1.5 hours.

[0104] The complete curing temperature is 115°C, the curing time is 2 hours, and the cooling time is 60 minutes.

[0105] Example 3: Method for manufacturing micro-terminal wires for consumer electronic devices

[0106] S1. Preparation of conductive adhesive

[0107] Raw material ratio:

[0108] Epoxy resin: 50wt%, silver powder: 20wt%, copper nanoparticles: 7wt%, carbon nanotubes: 2wt%, curing agent: 15wt%, toughening agent: 2wt%, dispersant: 1wt%, defoaming agent: 1wt%

[0109] Preparation steps:

[0110] 1. Stir the epoxy resin and curing agent at 300 rpm for 10 minutes.

[0111] 2. The copper nanoparticles were stirred at 1200 rpm for 30 minutes and treated with 30 kHz ultrasound for 10 minutes.

[0112] 3. Add silver powder all at once, stirring at 800 rpm for 8 minutes.

[0113] 4. Degassing in a vacuum degassing machine, pressure -0.1MPa, time 20 minutes.

[0114] 5. After adding the toughening agent, stir at low speed for 10 minutes at a speed of 500 rpm.

[0115] S2. Surface pretreatment

[0116] Strip 8 mm, clean the terminals and wires with isopropyl alcohol, and dry at 60°C for 5 minutes.

[0117] After sanding with 400-grit sandpaper, oxygen plasma treatment was used with a power of 150 W for 20 seconds.

[0118] S3. Coating of conductive adhesive

[0119] Using micro dispensing equipment, the coating thickness is 100μm and the dispensing speed is 1mm / s.

[0120] S4. Assembly of terminals and wires

[0121] The precision fixture aligns the wire and terminal and applies 12N of pressure for 3 minutes.

[0122] S5. Curing

[0123] Initial curing was at 60°C for 1 hour.

[0124] Fully cured at 100°C for 2 hours, cooling time 30 minutes.

[0125] Embodiment 4: Method for manufacturing a shock-resistant electric wire with terminal for electric tool harness

[0126] S1. Steps:

[0127] Raw material ratio:

[0128] Epoxy resin: 43wt%, silver powder: 27wt%, copper nanoparticles: 5wt%, carbon nanotubes: 3wt%, curing agent: 12wt%, toughening agent: 4wt%, dispersant: 1wt%, defoaming agent: 0.5wt%

[0129] Preparation steps:

[0130] 1. Stir the epoxy resin and curing agent at 500 rpm for 15 minutes.

[0131] 2. The copper nanoparticles and carbon nanotubes were mixed and stirred at 1200 rpm for 40 minutes, with an ultrasonic vibration frequency of 25 kHz for 12 minutes.

[0132] 3. Add silver powder in batches, stirring at 800 rpm, for 8 minutes each time.

[0133] 4. Degassing treatment pressure - 0.09MPa, time 15 minutes.

[0134] S2. Surface pretreatment

[0135] The stripping length is 10mm.

[0136] The wires and terminals were polished with 300-grit sandpaper, and then plasma treated with a power of 200 W for 25 seconds.

[0137] S3. Coating of conductive adhesive

[0138] The coating thickness is 200μm and the dispensing speed is 3mm / s.

[0139] S4. Assembly of terminals and wires

[0140] Use a clamp to fix and apply 16N pressure for 4 minutes.

[0141] S5. Curing

[0142] The initial curing temperature is 70°C and the time is 1 hour.

[0143] The complete curing temperature is 120°C, the curing time is 2 hours, and the cooling time is 50 minutes.

[0144] Example 5: Method for manufacturing precision wires with terminals for medical devices

[0145] S1. Preparation of conductive adhesive

[0146] Raw material ratio:

[0147] Epoxy resin: 44wt%, silver powder: 26wt%, copper nanoparticles: 6wt%, carbon nanotubes: 2.5wt%, curing agent: 13wt%, toughening agent: 3wt%, dispersant: 1wt%, defoaming agent: 0.5wt%

[0148] Preparation steps:

[0149] 1. Stir the epoxy resin and curing agent at 400 rpm for 15 minutes.

[0150] 2. The copper nanoparticles were stirred at 1000 rpm for 30 minutes and treated with 30 kHz ultrasound for 15 minutes.

[0151] 3. Add silver powder in batches, stirring at 1200rpm, for 5 minutes each time.

[0152] 4. Use vacuum degassing equipment, pressure -0.1MPa, time 10 minutes.

[0153] S2. Surface pretreatment

[0154] The peeling length was 6 mm, and the skin was ultrasonically cleaned with isopropyl alcohol for 3 minutes and then dried.

[0155] The wires and terminals were surface-gritted with 500-grit sandpaper, and then treated with oxygen plasma at 150 W for 15 seconds.

[0156] S3. Coating of conductive adhesive

[0157] Using a micro dispensing machine, the coating thickness is 120μm and the dispensing speed is 2mm / s.

[0158] S4. Assembly of terminals and wires

[0159] The precision fixture was aligned and a 10N pressure was applied for 2 minutes.

[0160] S5. Curing

[0161] The primary curing was carried out at 65°C for 1 hour.

[0162] Full curing was carried out at 105°C for 2 hours, with a cooling time of 40 minutes.

[0163] Comparative experiment 1:

[0164] Experimental Materials

[0165] The conductive adhesive of the present invention (experimental group): silver powder (25 wt%), copper nanoparticles (8 wt%), carbon nanotubes (3 wt%), epoxy resin, curing agent, toughening agent, dispersant and defoaming agent.

[0166] Comparative Example 1A: Only silver powder (30 wt %) was used, and other components were the same.

[0167] Comparative Example 1B: silver powder (20 wt %), copper powder (10 wt %), no carbon nanotubes, and other components are the same.

[0168] Experimental steps:

[0169] Step 1: Conductive Adhesive Preparation

[0170] The conductive adhesive of the present invention:

[0171] 1. Weigh epoxy resin, curing agent, silver powder, copper nanoparticles, carbon nanotubes, toughening agent, dispersant and defoaming agent according to the formula.

[0172] 2. Follow the steps to perform high shear dispersion and ultrasonic treatment, and finally perform vacuum degassing and secondary grinding.

[0173] Comparative Examples 1A and 1B:

[0174] The same preparation process was used, but the composition of the conductive filler was different. Comparative Example 1A used only silver powder, and Comparative Example 1B used silver powder and copper powder without adding carbon nanotubes.

[0175] Step 2: Sample preparation

[0176] 1. Surface preparation: Strip and clean the wires and terminals, and apply the same surface preparation (isopropyl alcohol cleaning, sandpaper polishing and oxygen plasma treatment).

[0177] 2. Adhesive coating: Use an automatic dispensing machine to apply the conductive adhesive to the terminals and wire connections with a coating thickness of 150μm.

[0178] 3. Assembly and curing:

[0179] After inserting the wire into the terminal, apply a pressure of 15N for 4 minutes.

[0180] Initial curing at 70°C for 1 hour, complete curing at 110°C for 2 hours, and natural cooling for 45 minutes.

[0181] Step 3: Experimental testing

[0182] 1. Conductivity test:

[0183] Use the four-terminal resistance method to test the resistance of the connection between the wire and the terminal. Test conditions: constant current 0.1A, room temperature.

[0184] 2. Tensile strength test:

[0185] Use an electronic tensile tester to perform a tensile test on the bonding area between the terminal and the wire, and record the maximum tensile force (N).

[0186] 3. Durability test:

[0187] The samples were placed in an environment of 85°C and 85% relative humidity for 72 hours, after which the resistance values ​​were retested to evaluate the stability of the adhesive in a high temperature and high humidity environment.

[0188] The experimental results are shown in the following table:

[0189]

[0190] Conclusion and Analysis

[0191] 1. Conductive properties

[0192] Initial resistance: The resistance value of the conductive adhesive of the present invention is 0.75 mΩ, which is significantly lower than 1.10 mΩ of Comparative Example 1A and 0.90 mΩ of Comparative Example 1B. This indicates that the combination of silver powder, copper nanoparticles and carbon nanotubes can form a denser and continuous conductive network, reducing resistance.

[0193] Durability resistance: After 72 hours of high temperature and high humidity environment, the resistance value of the adhesive of the present invention increased from 0.75mΩ to 0.80mΩ only, while the resistance of comparative example 1A increased from 1.10mΩ to 1.35mΩ, and the resistance of 1B increased from 0.90mΩ to 1.20mΩ. This shows that the adhesive of the present invention exhibits higher stability and durability in harsh environments, thanks to the introduction of carbon nanotubes, which improves the material's oxidation resistance and mechanical stability.

[0194] 2. Bonding strength

[0195] Tensile strength: The tensile strength of the present invention reaches 65 N, while the strengths of Comparative Examples 1A and 1B are 55 N and 58 N, respectively. The adhesive of the present invention exhibits higher bonding strength, which is mainly due to the synergistic effect of copper nanoparticles and carbon nanotubes, which enhance the structural strength of the adhesive.

[0196] 3. Comprehensive analysis

[0197] Superior conductivity: The present invention adopts a combination of silver powder, copper nanoparticles and carbon nanotubes, which not only shows significant advantages in initial conductivity, but also maintains excellent stability in high temperature and high humidity environments.

[0198] Improved bonding strength: The tensile strength of the conductive adhesive of the present invention is higher than that of the comparative example, indicating that the introduction of copper nanoparticles and carbon nanotubes improves the bonding strength and fatigue resistance of the adhesive.

[0199] In summary, the conductive adhesive of the present invention is significantly superior to the comparative example in terms of conductive performance, bonding strength and durability, which verifies its technical advantages in various application scenarios.

[0200] Comparative experiment 2:

[0201] Experimental Materials

[0202] The preparation process of the present invention (experimental group) includes high shear dispersion, ultrasonic treatment, vacuum degassing and secondary grinding.

[0203] Comparative Example 2A: No ultrasonic treatment was used, only high shear dispersion was used.

[0204] Comparative Example 2B: No secondary grinding was performed, and other steps were the same as those of the present invention.

[0205] Experimental procedures

[0206] Step 1: Preparation of Conductive Adhesive

[0207] 1. Preparation process of the present invention (experimental group):

[0208] High shear dispersion: epoxy resin, curing agent, copper nanoparticles and carbon nanotubes were mixed using a high shear disperser at a stirring speed of 1000-1500 rpm for 40 minutes.

[0209] Ultrasonic treatment: Ultrasonic vibration treatment (frequency of 25 kHz, duration of 15 minutes) was used simultaneously to ensure uniform dispersion of the nanoparticles.

[0210] Silver powder is added in batches: silver powder is added in batches, stirring at a speed of 1200 rpm, and stirring for 5-10 minutes each time.

[0211] Vacuum degassing: degassing at -0.1 MPa for 20 minutes.

[0212] Secondary grinding: Use double-roll grinding equipment, set the pressure at 250N, and grind for 15 minutes.

[0213] 2. Comparative Example 2A Preparation process:

[0214] The mixing was performed using a high shear dispersing device, and the stirring speed and time were consistent with the present invention, but no ultrasonic treatment was performed.

[0215] Silver powder was added in batches and vacuum degassing was performed, with the pressure and time being kept consistent.

[0216] The secondary grinding is carried out, and the pressure and time are kept the same as the present invention.

[0217] 3. Comparative Example 2B Preparation Process:

[0218] According to the process of the present invention, high shear dispersion, ultrasonic treatment, silver powder addition and vacuum degassing are performed, but secondary grinding is not performed.

[0219] Step 2: Sample preparation

[0220] 1. Surface treatment: Strip the wires and terminals, clean with isopropyl alcohol, sand and plasma treat to ensure consistent surface cleaning and activation.

[0221] 2. Apply conductive adhesive: Use an automatic dispensing machine to apply the adhesive to the connection between the terminal and the wire, with a coating thickness of 150μm.

[0222] 3. Assembly and curing:

[0223] Insert the wire into the terminal and apply 15N of pressure for 4 minutes.

[0224] Initial curing is at 70°C for 1 hour, full curing is at 110°C for 2 hours, and cooling time is 45 minutes.

[0225] Step 3: Experimental testing

[0226] 1. Conductivity test:

[0227] Use the four-terminal resistance method to measure the resistance value at the connection between the wire and the terminal, and the test current is 0.1A.

[0228] 2. Bond strength test:

[0229] Use an electronic tensile tester to perform a tensile test on the bonding area between the terminal and the wire, and record the maximum pull-off strength.

[0230] 3. Filler dispersion test:

[0231] The cured cross section of the conductive adhesive was observed using a scanning electron microscope to analyze the uniformity of filler dispersion and particle agglomeration.

[0232] The experimental results are shown in the following table:

[0233]

[0234]

[0235] Conclusion and Analysis

[0236] 1. Conductive properties

[0237] Initial resistance: The resistance value of the conductive adhesive of the present invention is 0.75 mΩ, which is significantly lower than that of Comparative Example 2A (0.90 mΩ) and Comparative Example 2B (0.85 mΩ). This shows that the ultrasonic treatment and secondary grinding process have a significant effect on improving the conductive performance. The ultrasonic treatment can effectively disperse the nanofiller to ensure the formation of a denser conductive network, while the secondary grinding further ensures that the conductive particles are in full contact with the resin.

[0238] 2. Bonding strength

[0239] The bonding strength of the present invention reaches 65N, which is significantly higher than 55N of Comparative Example 2A and 58N of Comparative Example 2B. This shows that the complete preparation process can make the components of the adhesive evenly dispersed, improving the overall bonding performance of the material. In Comparative Example 2A, which does not use ultrasonic treatment, the filler cannot be fully dispersed, resulting in reduced bonding strength; in Comparative Example 2B, which does not perform secondary grinding, the bonding strength is also reduced due to insufficient contact between the silver powder and the matrix resin.

[0240] 3. Filler dispersion

[0241] Scanning electron microscopy (SEM) was used to observe that the conductive adhesive of the present invention had the most uniform filler distribution and the least particle agglomeration, with a score of 5 (highest). In Comparative Example 2A, due to the lack of ultrasonic treatment, the filler showed obvious agglomeration, and the uniformity score was 3; in Comparative Example 2B, although ultrasonic treatment was performed, the particle distribution was not uniform due to the lack of secondary grinding, and the score was 4.

[0242] Comprehensive analysis

[0243] Process advantages: The preparation process of the present invention ensures the uniform dispersion of the conductive filler and the full combination with the epoxy resin matrix through the steps of high shear dispersion, ultrasonic treatment, vacuum degassing and secondary grinding, thereby significantly improving the conductive performance and bonding strength.

[0244] Importance of ultrasonic treatment: Ultrasonic treatment effectively breaks up the agglomeration of nanoparticles and improves the continuity and stability of the conductive path.

[0245] The role of secondary grinding: Secondary grinding further improves the contact between filler and substrate, and improves bonding strength and conductivity.

[0246] The preparation process of the present invention has significant advantages in improving the performance of conductive adhesives, ensuring the stability of conductive properties and high bonding strength, and is significantly better than the comparative process without ultrasonic treatment or secondary grinding.

[0247] Comparative experiment 3:

[0248] Experimental Materials

[0249] The curing process of the present invention (experimental group): gradual temperature increase curing (60-80° C. for preliminary curing, 100-120° C. for complete curing) + natural cooling.

[0250] Comparative Example 3A: One-time curing (curing at 120° C. for 3 hours).

[0251] Comparative Example 3B: Natural curing at room temperature without heating curing process.

[0252] Experimental setup and steps

[0253] Step 1: Preparation of Conductive Adhesive

[0254] The same conductive adhesive formula and preparation process (including silver powder, copper nanoparticles, carbon nanotubes, epoxy resin, curing agent, etc.) were used to ensure that the adhesive composition of all experimental groups was consistent.

[0255] Step 2: Sample preparation

[0256] 1. Surface treatment: Clean the wires and terminals with isopropyl alcohol, sandpaper, and treat with oxygen plasma to ensure consistent surface pretreatment process.

[0257] 2. Apply conductive adhesive: Use an automatic dispensing machine to apply the conductive adhesive to the connection between the terminal and the wire. The coating thickness is 150μm and the dispensing speed is 2mm / s.

[0258] 3. Assembly: Insert the wire into the terminal and apply 15N pressure for 4 minutes.

[0259] Step 3: Curing process

[0260] 1. Curing process of the present invention (experimental group):

[0261] Initial curing: Place the sample in a 60-80°C environment for 1-2 hours to ensure that the adhesive is initially cross-linked and has initial strength.

[0262] Fully cure: Raise the temperature to 100-120°C and continue heating for 2-3 hours to ensure that the epoxy resin is fully cross-linked to form a high-strength bonding interface and conductive network.

[0263] Cooling: Cool naturally at room temperature for 30-60 minutes to avoid stress cracking caused by rapid cooling.

[0264] 2. Comparative Example 3A (one-time curing):

[0265] The sample was heated to 120°C for 3 hours and then taken out and cooled naturally.

[0266] 3. Comparative Example 3B (natural curing):

[0267] The sample was cured naturally at room temperature without heating, and the curing time was 24 hours.

[0268] Step 4: Experimental testing

[0269] 1. Bond strength test:

[0270] Use an electronic tensile tester to test the bonding strength between the terminal and the wire, and record the maximum tensile force (N).

[0271] 2. Conductivity test:

[0272] The resistance at the connection between the wire and the terminal is measured using the four-terminal resistance method. The test condition is 0.1A current and is carried out at room temperature.

[0273] 3. Heat resistance test:

[0274] The samples were placed in a high temperature environment of 120°C for 72 hours, and the conductivity (resistance value) and bonding strength were retested to evaluate the thermal stability after curing.

[0275] The experimental results are shown in the following table:

[0276]

[0277]

[0278] Conclusion and Analysis

[0279] 1. Bonding strength

[0280] The bonding strength of the curing process of the present invention reaches 65N, which is significantly higher than the comparative example 3A (55N) of one-time curing and the comparative example 3B (48N) of room temperature curing. The curing process of gradually increasing the temperature can better control the cross-linking reaction of the adhesive, ensure the full cross-linking of the epoxy resin and the filler, and form a high-strength bonding interface, while the one-time curing may cause stress concentration and reduce the bonding strength. The sample cured at room temperature showed the lowest bonding strength due to incomplete curing.

[0281] 2. Conductive properties

[0282] Initial resistance: The initial resistance of the present invention is 0.75 mΩ, which is better than the one-time curing comparative example 3A (0.90 mΩ) and the room temperature curing comparative example 3B (1.20 mΩ). Gradually increasing the temperature to cure allows the conductive filler to have sufficient time to disperse and contact during the curing process, forming a denser conductive network, while one-time curing and natural curing have higher resistance values ​​due to insufficient dispersion of the conductive filler.

[0283] 3. Heat resistance

[0284] Conductive performance after 72 hours of high temperature: After being placed in a high temperature environment of 120°C for 72 hours, the resistance value of the present invention only increased from 0.75mΩ to 0.80mΩ, and the conductive performance had almost no significant change. However, the resistance of Comparative Example 3A increased from 0.90mΩ to 1.10mΩ, and that of Comparative Example 3B increased from 1.20mΩ to 1.50mΩ. This shows that the step-curing process can enhance the thermal stability of the adhesive, allowing it to maintain good conductive performance in a high temperature environment.

[0285] Bond strength after 72 hours of high temperature: The bond strength of the present invention is maintained at 63N in a high temperature environment, showing excellent heat resistance. The bond strength of Comparative Example 3A dropped significantly to 45N, while that of Comparative Example 3B dropped significantly to 30N, indicating that the samples that were not fully cured showed poor bond strength and stability at high temperatures.

[0286] 4. Comprehensive analysis

[0287] Advantages of the step-by-step curing process: The step-by-step curing process adopted by the present invention can make the epoxy resin and the conductive filler in the conductive adhesive fully react and disperse through gradual heating and natural cooling to form a more stable structure, thereby improving the bonding strength, conductive properties and heat resistance.

[0288] Disadvantages of one-time curing: Although the bonding strength and conductivity of comparative example 3A are acceptable in the initial stage, internal stress is easily generated due to one-time high-temperature curing, resulting in performance degradation in a long-term high-temperature environment.

[0289] Insufficient natural curing: Comparative Example 3B was not cured by heating, resulting in the failure of complete cross-linking of the adhesive, insufficient curing, poor bonding strength and conductivity, and extremely poor durability in high temperature environments.

[0290] The step-by-step curing process of the present invention significantly improves the bonding strength and conductive properties of the conductive adhesive, and particularly exhibits excellent thermal stability and long-term reliability under high temperature conditions, which is superior to one-time curing and natural curing methods.

[0291] Comparative experiment 4:

[0292] Experimental Materials

[0293] The method of the present invention (experimental group): using a conductive adhesive (the formulation is the same as the above-mentioned best solution), the manufacturing method of the present invention is adopted to bond the terminal and the wire.

[0294] Comparative Example 4 (traditional mechanical crimping): Use wires and terminals of the same specifications and connect them using mechanical crimping.

[0295] Experimental setup and steps

[0296] Step 1: Sample preparation

[0297] 1. The method of the present invention (experimental group):

[0298] Surface preparation: Clean the wires and terminals with isopropyl alcohol, sandpaper, and oxygen plasma to ensure a clean surface.

[0299] Applying conductive adhesive: Use an automatic dispensing machine to apply the adhesive to the connection area between the wire and the terminal, with a coating thickness of 150μm and a dispensing speed of 2mm / s.

[0300] Assembly and curing: Insert the wire into the terminal and apply 15N pressure for 4 minutes. Initial curing at 70℃ for 1 hour, complete curing at 110℃ for 2 hours, and natural cooling for 45 minutes.

[0301] 2. Comparative Example 5 (traditional mechanical crimping):

[0302] Use a standard mechanical crimping tool to connect the wire to the terminal, ensuring the crimping force is uniform and the crimping pressure is 20N.

[0303] Step 2: Experimental testing

[0304] 1. Conductivity test:

[0305] The four-terminal resistance method is used to test the resistance value of the connection between the wire and the terminal. The test conditions are 0.1A current and room temperature.

[0306] 2. Bond strength test:

[0307] Use an electronic tensile tester to perform a tensile test on the connection between the terminal and the wire, and record the maximum breaking strength (N).

[0308] 3. Anti-vibration test:

[0309] The sample was fixed on a vibration table and subjected to a high-frequency vibration test with a vibration frequency of 50 Hz, an amplitude of 2 mm, and a test time of 4 hours. The resistance change and connection integrity after the test were recorded.

[0310] 4. Corrosion resistance test:

[0311] The samples were placed in a salt spray test chamber for 48 hours of salt spray corrosion test (salt solution concentration 5%, temperature 35°C), and then the resistance value and bonding strength were remeasured to evaluate the corrosion resistance.

[0312] The experimental results are shown in the following table:

[0313]

[0314]

[0315] Conclusion and Analysis

[0316] 1. Conductive properties

[0317] Initial resistance: The conductive adhesive bonding method of the present invention exhibits a lower initial resistance value (0.75mΩ), which is significantly better than the traditional mechanical crimping method (1.10mΩ). This is because the adhesive can provide a more uniform distribution of conductive fillers and a denser conductive path, while mechanical crimping has a relatively high contact resistance due to uneven contact.

[0318] 2. Bonding strength

[0319] The bonding strength of the present invention is 65N, which is higher than the 50N of mechanical crimping. This shows that conductive adhesive bonding can provide stronger bonding force at the connection to ensure the stability of the connection. Mechanical crimping is prone to fatigue and loosening of the connection due to stress concentration, and has a lower bonding strength.

[0320] 3. Anti-vibration performance

[0321] After the vibration test, the resistance value of the sample of the present invention only slightly increased to 0.80mΩ, indicating that the connection part maintained good conductivity under high-frequency vibration conditions. The resistance value of the mechanically crimped sample increased from 1.10mΩ to 1.40mΩ, indicating that the connection part became loose or had poor contact during the vibration process. The conductive adhesive bonding of the present invention can better absorb and disperse vibration and maintain the stability of the conductive path.

[0322] 4. Corrosion resistance

[0323] After the salt spray corrosion test: the resistance value of the present invention increased from 0.75mΩ to 0.85mΩ, and the bonding strength remained at 62N, showing excellent corrosion resistance. The resistance value of comparative example 5 increased from 1.10mΩ to 1.80mΩ, and the bonding strength decreased to 40N, showing poor corrosion resistance. Mechanical crimping is prone to increase contact resistance due to metal oxidation and corrosion, reducing conductivity and connection strength.

[0324] 5. Comprehensive analysis

[0325] Conductivity: The conductive adhesive bonding method of the present invention is significantly superior to mechanical crimping in terms of conductivity, exhibiting lower resistance values ​​and more stable conductive paths.

[0326] Bond Strength: Conductive adhesive bonding methods provide higher bond strength, ensuring stability and durability of the connection.

[0327] Anti-vibration and corrosion resistance: The present invention exhibits stronger stability and durability in high vibration and corrosion environments, and is suitable for applications in harsh environments.

[0328] The conductive adhesive bonding method of the present invention is significantly superior to the traditional mechanical crimping method in terms of conductivity, bonding strength, vibration resistance and corrosion resistance, and is particularly suitable for application scenarios with high requirements for reliability and durability.

[0329] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a terminal-equipped electric wire, characterized in that: The following steps are involved: S1. preparing a conductive adhesive: mixing epoxy resin, silver powder, copper nanoparticles, carbon nanotubes, a curing agent, a toughening agent, a dispersant and a defoaming agent in proportion, and obtaining a conductive adhesive through premixing, nanoparticle dispersion, gradual addition of silver powder, defoaming treatment, toughening agent addition and secondary dispersion; S2. Surface pretreatment: stripping, surface cleaning, surface roughening and activation of wires and terminals; S3, applying a conductive adhesive: applying a conductive adhesive to a connection area between a conductor and a terminal of the wire; S4. Assembly of terminals and wires: insert the wires into the terminals and apply pressure for bonding; S5. Curing: Place the connector in an environment of 60-80℃ for preliminary curing for 1-2 hours, and then fully cure it in an environment of 100-120℃ for 2-3 hours.

2. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The conductive adhesive comprises the following raw materials: Epoxy resin: 40-50wt%; Silver powder: 20-30wt%; Copper nanoparticles: 5-10wt%; Carbon nanotubes: 2-5wt%; Curing agent: 10-15wt%; Toughening agent: 2-5wt%; Dispersant: 1-2wt%; Defoaming agent: 0.5-1wt%.

3. A method for manufacturing a terminal-equipped electric wire according to claim 1 or 2, characterized in that: The nanoparticle dispersion step uses a high shear dispersion device with a stirring speed of 1000-1500 rpm and a dispersion time of 30-45 minutes, combined with 20-30 kHz ultrasonic vibration treatment for 10-15 minutes to ensure uniform distribution of the nanoparticles.

4. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The silver powder is dried at 100-120° C. before being added, and the drying time is 30-50 minutes.

5. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The surface pretreatment comprises: Use 300-500 grit sandpaper to sand the exposed conductor surfaces of the terminals and wires; Oxygen plasma treatment is used, the plasma power is 150-200W, and the treatment time is 20-30 seconds.

6. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The conductive adhesive is coated using an automatic dispensing machine, with a coating thickness of 100-200 μm and a dispensing speed of 1-3 mm / s.

7. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The steps of assembling the terminal and the wire include: After applying the conductive adhesive, use a positioning fixture to ensure accurate alignment of the wire to the terminal and apply 10-20N of pressure for 3-5 minutes to ensure adequate penetration of the conductive adhesive.

8. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The curing step comprises: The initial curing process is carried out at 60-80°C for 1-2 hours; The complete curing process is carried out at 100-120°C and takes 2-3 hours; Finally, cool naturally to room temperature, the cooling time is 30-60 minutes.

9. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The secondary dispersion of the conductive adhesive is carried out using a double-roll grinding device, with a grinding pressure of 200-300N and a grinding time of 10-15 minutes.

10. The method for manufacturing a terminal-equipped electric wire according to claim 1, characterized in that: The prepared conductive adhesive is subjected to vacuum degassing treatment before use, the vacuum degree is -0.08 to -0.1 MPa, and the degassing time is 10 to 20 minutes.

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