Method for welding Pin and enameled wire

Abstract

The invention relates to the field of welding, in particular to a Pin and enameled wire welding method which comprises the following steps that S1, an enameled wire is tightly attached to the surface of a Pin to be wound to form a winding Pin, the gap between two winding circles on the top is smaller than or equal to 0.2 mm, enough gaps are kept between the two winding circles on the top and the winding circles on the lower portion, and the gap is larger than or equal to 0.2 mm; the distance from a circle of winding wire close to the topmost part of the Pin to the top of the Pin is less than or equal to 5 times of the maximum side length of the Pin; s2, short-wavelength laser with the wavelength smaller than 600 nm is adopted for irradiation, the distance from the center irradiation position of a laser spot to the top enameled wire is smaller than two times of the side length of the Pin needle, the distance from the center irradiation position of the laser spot to the top enameled wire is larger than half of the diameter of the light spot, the welding power ranges from 50 W to 500 W, the welding time ranges from 50 ms to 1000 ms, and a product is obtained through welding; the welding method can be suitable for the welding stability of various types of enameled wires and pins, meanwhile, the welding efficiency is improved, the welding effect is improved, and the problem that the enameled wires are prone to being burnt out in the welding process is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding, in particular to a Pin needle and enameled wire welding method. BACKGROUND

[0002] In the field of electronic manufacturing technology, the manufacturing of precision electronic components such as motors, sensors, and electronic connectors plays a crucial role. With the continuous advancement of technology, electronic devices are constantly moving towards miniaturization and precision, which puts more stringent requirements on the manufacturing process of electronic components. Pin needle and enameled wire welding, as a core link in the manufacturing process of precision electronic components, its welding quality and efficiency directly affect the performance and reliability of the entire electronic component. An efficient and high-quality welding method can improve the stability and durability of electronic components, reduce the probability of failure, thereby reducing production costs and improving the market competitiveness of products.

[0003] To achieve the welding of Pin needle and enameled wire, the industry usually adopts the following methods, one is to remove the insulating paint on the surface of the enameled wire by mechanical pre-peeling, then to drop the molten tin ball on the exposed copper wire, and then to weld the tin ball and the Pin needle, to achieve the effect of firm welding of enameled wire and Pin needle. Another is to use long-wavelength infrared laser welding technology, which uses 1064nm laser with high energy to directly connect the enameled wire and Pin needle. This technology takes advantage of the concentrated characteristics of laser energy, greatly improving the welding efficiency; some enterprises have also introduced "de-painting-welding integrated equipment", which uses double-wavelength laser to work together, and through the cooperation of different wavelengths of laser, to improve the efficiency and quality of welding.

[0004] However, these existing welding technologies still have many defects in actual application. On the one hand, the mechanical peeling of the insulating paint method has low welding efficiency, and in the process of peeling the insulating paint, the mechanical tool is easy to damage the wire and destroy the internal structure of the wire, affecting its conductivity; on the other hand, the long-wavelength infrared laser welding technology greatly improves the welding efficiency, but due to the low absorption rate of copper substrate and large heat-affected zone, the problem of burning out the enameled wire is easy to occur during welding. In addition, the double-wavelength laser works together, but a lot of laser energy is still wasted, especially for different types of enameled wire paint, such as water-based polyester-TiO2 composite paint, polyurethane-silane composite paint and polyimide-Al2O3 composite paint, which need to adjust the parameters according to the specific paint type, which is complicated to operate, increases the production cost and time cost, and the laser absorption rate of different types of paint is difficult to grasp, which may lead to insufficient welding strength and blackening phenomenon at the welding site. SUMMARY

[0005] In order to ensure that the welding stability can be suitable for various types of enameled wires and pin needles, improve the welding efficiency and welding effect, and effectively avoid the problem of easy burning of enameled wires in the welding process, the application provides a welding method for pin needle and enameled wire.

[0006] The application provides a welding method for pin needle and enameled wire, which comprises the following steps: S1: winding the enameled wire closely around the surface of the pin needle to form a winding pin needle, the gap between the top two windings is less than or equal to 0.2 mm, the top two windings and the lower windings maintain sufficient gap, the gap is greater than or equal to 0.2 mm, and the distance from the winding close to the topmost winding of the pin needle to the top of the pin needle is less than or equal to 5 times the maximum side length of the pin needle; S2: irradiating with short-wavelength laser with wavelength < 600 nm, the distance from the center of the laser spot to the top enameled wire is less than 2 times the pin needle length, the distance from the center of the laser spot to the top enameled wire is greater than half the spot diameter, the welding power is 50-500 W, the welding time is 50-1000 ms, the top pin needle of the enameled wire is completely melted, the enameled wire is partially melted, the mixed melt after melting of the two wraps the un-melted enameled wire, cools and solidifies to form a solder ball, realizing the welding of the pin needle and the enameled wire to obtain a product. Through the above technical solution, in step S1, the gap between the top two windings is ≤0.2 mm, and the gap between the top two windings and the lower winding is ≥0.2 mm. Such winding mode can make the enameled wire and the pin needle closely fit and reasonably distributed, increase the contact area and contact tightness of the two, provide a good foundation for subsequent welding, and is beneficial to improve the firmness of welding. In step S2, short-wavelength laser with wavelength < 600 nm is used, and the absorption rate of copper substrate to short-wavelength laser is higher than that of long-wavelength infrared laser, which can more effectively transfer energy to the enameled wire and the pin needle. The distance from the center of the laser spot to the top enameled wire is greater than half the spot diameter, the welding power is 50-500 W, the welding time is 50-1000 ms, the top pin needle of the enameled wire is completely melted, the enameled wire is partially melted, the mixed melt after melting of the two wraps the un-melted enameled wire, cools and solidifies to form a solder ball, realizing the welding of the pin needle and the enameled wire to obtain a product. Sufficient energy can make the enameled wire and the pin needle fully melt and combine, thereby improving the welding strength and stability, and finally obtaining a high-quality welding product, effectively solving the problems of low welding efficiency, easy damage to the lead wire, waste of laser energy, insufficient welding strength and the like in the existing welding technology. Preferably, the short-wavelength laser is 532 nm green light or 450 nm blue light. Through the above technical solution, 532 nm green light or 450 nm blue light is selected as the short-wavelength laser, and the absorption rate of copper substrate to short-wavelength laser is higher than that of long-wavelength infrared laser. During welding, higher absorption rate means that laser energy can be more effectively utilized, which can reduce energy waste. At the same time, since the short-wavelength laser energy is concentrated, it can more accurately act on the target area during paint removal and welding, the heat-affected zone is smaller, the risk of burning the enameled wire can be reduced, and the welding quality and stability can be improved, thereby improving the efficiency of pin needle and enameled wire welding and the reliability of the welding site.

[0007] Preferably, in S2, the paint is removed by an asymmetric bipolar pulse waveform with a front power of 800-1500 W and a duration of 100-500 ns, a rear power of 300-600 W and a duration of 500-1500 ns, and a total energy density of 3-6 J / cm² before welding.

[0008] By adopting the above technical scheme, the asymmetric bipolar pulse waveform with the front edge power of 800-1500 W, the front edge duration of 100-500 ns, the rear edge power of 300-600 W, the rear edge duration of 500-1500 ns, and the total energy density of 3-6 J / cm2 is used before welding, the high power of the front edge can quickly act on the paint skin, the paint skin is rapidly heated and removed, the low power of the rear edge can avoid excessive energy concentration to burn the enameled wire, and the suitable total energy density can not only ensure the effective removal of the paint skin, but also reduce the damage to the internal structure of the wire, which is beneficial to the precision and effect of subsequent welding.

[0009] Preferably, after the paint skin is removed, the product is obtained by first performing plasma pretreatment and then performing welding in a protective gas environment.

[0010] By adopting the above technical scheme, after removing the paint skin, the welding surface can be activated and the wettability and bonding force of welding can be improved by cooperating with plasma pretreatment in a protective gas environment. Preferably, the flow rate of the protective gas is 5-30 m / s. By adopting the above technical scheme, the flow rate of the protective gas is set to 5-30 m / s, and the appropriate flow rate can make the protective gas uniformly cover the welding area, which can avoid problems such as oxidation and blackening of the welding part, improve the welding strength and stability, and thus improve the overall performance and reliability of the pin and enameled wire welding product. Preferably, the protective gas is a mixture of argon and hydrogen with a component ratio of 8-9:1-2. By adopting the above technical scheme, the mixture of argon and hydrogen with a component ratio of 8-9:1-2 is used as the protective gas. Argon is chemically stable and can prevent the oxidation of metal during welding. Hydrogen has reducing properties and can further remove oxides on the surface of the metal to ensure the cleanliness of the welding part. Preferably, the laser defocusing amount during the paint removal process of S2 is ≤±5 mm, and the laser defocusing amount during the welding process of S2 is ±3 mm. By adopting the above technical scheme, the laser defocusing amount is set to ≤±5 mm during the paint removal process of S2, which can make the short-wavelength laser more reasonably distribute the laser energy within the appropriate defocusing range when irradiating the enameled wire. The laser defocusing amount is set to ±3 mm in S3. Compared with the larger defocusing amount of S2, the laser defocusing amount ±3 mm during the welding process of S2 can make the laser energy more concentrated on the welding area between the pin and the copper substrate, reducing energy dispersion and thus improving the energy utilization rate of welding and the welding efficiency. The designed laser energy can effectively remove the paint skin without causing excessive damage to the enameled wire, thereby improving the efficiency and quality of paint removal and making the welding process more stable, avoiding problems such as insecure welding caused by energy dispersion, and ensuring the strength and quality of the welding part. Preferably, the included angle between the laser beam of S2 and the pin is 10-75°. By adopting the above technical scheme, the included angle between the laser beam of S2 and the pin is set to 10-75°, which can make the laser act on the welding part at a suitable angle. When the included angle is within this range, the laser energy can be more uniformly distributed at the welding part of the pin and the enameled wire, avoiding excessive concentration or dispersion of energy. If the included angle is too small, the laser may be reflected on the surface of the pin, causing energy loss and affecting the welding effect. If the included angle is too large, the laser may not effectively act on the welding part, also reducing the welding quality. The appropriate included angle can improve the utilization rate of laser energy, make the welding more secure, enhance the stability and reliability of the welding part, and thus improve the performance of the entire welding product, reduce the probability of failure, and improve the market competitiveness of the product.By adopting the technical scheme, since the laser irradiation can cause reflection and leakage, if not handled, the reflection and leakage can cause burning to the welding product, affecting the product quality. The light shield plate placed near the Pin needle can effectively block the reflection and leakage of the laser, avoiding damage to the welding product, thereby improving the yield of the welding product, reducing the production cost, and ensuring the stability and reliability of the welding quality.

[0011] Preferably, the laser irradiation position in S2 is obtained by a vision camera to obtain a spatial coordinate, and the welding head is guided to move to the corresponding position to emit light for welding.

[0012] By adopting the technical scheme, the spatial coordinate is obtained by the vision camera, and the welding head is guided to move to the corresponding position to emit light for welding, which can improve the precision and flexibility of welding, thereby improving the effect of welding.

[0013] In summary, the present application has at least one of the following beneficial technical effects: 1. By tightly winding the enameled wire around the surface of the Pin needle, the gap between the top two windings is ≤0.2mm, and the gap between the top two windings and the lower winding is ≥0.2mm, short-wavelength laser irradiation with a wavelength <600nm is used, and the distance from the laser spot center irradiation position to the top enameled wire is less than 2 times the side length of the Pin needle, and the distance from the laser spot center irradiation position to the top enameled wire is greater than half the spot diameter, which creates good conditions for subsequent short-wavelength laser welding. Because of this winding method, the laser can more accurately act on the enameled wire, avoiding direct contact between mechanical tools and wires compared to mechanical stripping of the insulating paint, thereby avoiding the problem of mechanical stripping damage to the wire, improving the welding speed, and further improving the welding efficiency; 2. Before welding, an asymmetric bipolar pulse waveform with a front power of 800-1500W and a duration of 100-500ns, and a rear power of 300-600W and a duration of 500-1500ns, and a total energy density of 3-6J / cm² is used to remove the paint, and then welding is performed. Due to the characteristics of short-wavelength laser, its absorption rate on copper substrate is higher than that of long-wavelength infrared laser, and the heat-affected zone is relatively small, which solves the problem of easy burning of enameled wire caused by low absorption rate and large heat-affected zone of long-wavelength infrared laser during welding, and improves the paint removal efficiency and further improves the welding quality, avoiding the problem of black marks left by paint during welding; 3. Use of protective gas, first treated by plasma pretreatment and then welded. The protective gas can provide a stable welding environment, and the plasma pretreatment can clean the welding surface, improve the bonding strength of the welding, and improve the laser energy density to make the welding more sufficient, avoiding the problems of laser energy waste and parameter adjustment in the double-wavelength laser cooperative method, improving the welding strength, and reducing the blackening phenomenon at the welding site. DETAILED DESCRIPTION

[0014] The Pin needle and enameled wire welding method provided by the embodiment of the application comprises the steps of enameled wire winding, short-wavelength laser paint removal, mixed gas protection plasma pretreatment and welding. In the method, the enameled wire is wound on the Pin needle according to specific requirements, the paint is removed by using short-wavelength laser and specific pulse waveform, the specific mixed gas protection is used in combination with plasma pretreatment, and finally the welding is performed by increasing the laser energy density, so that the welding quality and efficiency are improved, the damage to the wire is reduced, and the welding defects are avoided. This is because the specific winding method can make the enameled wire and the Pin needle closely combined, the short-wavelength laser can efficiently remove the paint and reduce the damage to the wire under the specific pulse waveform, the mixed gas protection and the plasma pretreatment can prevent the oxidation and other problems in the welding process, and the welding quality is improved.

[0015] Specifically, in the S1 step of enameled wire winding, the enameled wire needs to be wound on the surface of the Pin needle to form a winding Pin needle. The enameled wire is generally a metal wire with an insulating paint on the surface, and the common metal material is copper. The shape of the enameled wire is generally a wire-shaped line with a circular cross section. The Pin needle is generally a metal needle-shaped component, and the material can be copper, iron or other metals. When winding, the operator needs to operate carefully, fixes one end of the enameled wire at the top of the Pin needle, and then winds downward, so that the gap between the two winding turns at the top is ≤0.2mm, the gap between the two winding turns at the top and the winding turns below is ≥0.2mm, and the distance from the winding turn close to the top of the Pin needle to the top of the Pin needle is ≤5 times the maximum side length of the Pin needle. The winding method can be that the operator first fixes one end of the enameled wire at the bottom of the Pin needle, and then winds upward, as long as the above gap and distance requirements are met.

[0016] Specifically, in the S2 step, the paint is first removed by irradiation with a short-wavelength laser having an asymmetric bipolar pulse waveform and a wavelength < 600 nm, and the distance between the laser irradiation position and the top enameled wire is less than 2 times the side length or diameter of the pin, and the distance between the center of the laser spot and the top enameled wire is greater than half the spot diameter. The short-wavelength laser can be a 532 nm green light or a 450 nm blue light, and the like. The preferred embodiment is a 450 nm blue light. In the process of removing the paint, the laser parameters are as follows: the front edge power is 800 - 1500 W, the duration is 100 - 500 ns; the back edge power is 300 - 600 W, the duration is 500 - 1500 ns, and the total energy density is 3 - 6 J / cm2 of an asymmetric bipolar pulse waveform. The front edge power of the present embodiment is selected to be 1000 W, the duration is 200 ns; the back edge power is selected to be 400 W, the duration is 800 ns, and the total energy density is 5 J / cm2. When setting these parameters, professional laser control equipment needs to be used to ensure the accuracy and stability of the parameters.

[0017] In particular, the pin of the present embodiment is a straight quadrangular prism with a bottom side length of 0.5*0.5 mm, the focal spot diameter can be selected between 0.15 - 1 mm, the preferred embodiment is 0.4 mm, and the distance between the center of the laser spot and the top enameled wire is 0.5 mm. The focal spot diameter of the laser irradiation can also be fine-tuned according to the actual situation, as long as it can guarantee the paint removal effect within a reasonable range.

[0018] Further, the laser defocusing amount in the process of removing the paint in the S2 step is ≤ ± 5 mm, and the laser focal point of the present embodiment is adjusted within a range of 5 mm above and below the surface of the pin. When adjusting the defocusing amount, a high-precision displacement adjusting device needs to be used to ensure accurate control of the defocusing amount.

[0019] Specifically, after removing the paint, a mixed gas with a composition ratio of argon to hydrogen of 8 - 9:1 - 2 is used as a protective gas, and the present embodiment is 90% argon and 10% hydrogen. The mixed gas is axially delivered to the surface of the pin, and the flow rate of the mixed gas is 5~30m / s. When providing the mixed gas, professional gas mixing devices and flow control equipment need to be used to ensure the accuracy and stability of the ratio and flow rate of the mixed gas. And cooperate with the plasma pretreatment with a power of 50 - 100 W and a processing time of 10 - 30 seconds, the plasma pretreatment is realized by using plasma generator and the like. After all the preparations are completed, the welding is continued under the irradiation of the short-wavelength laser with a wavelength < 600 nm to obtain the welded product. In the welding process, the focal spot diameter of the laser is 0.6 mm, and the distance between the center of the laser spot and the top enameled wire is 0.5 mm, which can make the welding more sufficient.

[0020] Particularly, the laser defocusing amount in the welding process in S2 is ±3 mm, that is, the laser focal point is adjusted within the range of 3 mm above and below the surface of the Pin needle. The angle between the laser beam of the paint removal process in S3 and the Pin needle and the angle between the laser beam of the welding process and the Pin needle are both 10-75°, and the preferred angle in this embodiment is 30°. When adjusting the angle between the laser beam and the Pin needle, an angle adjusting device is used to ensure accurate setting of the angle.

[0021] Further, a light shield plate is placed near the Pin needle, which can be made of metal, plastic or other materials. Its function is to avoid reflection and light leakage from burning the welding product. When placing the light shield plate, the position of the light shield plate should be appropriate to effectively block the reflection and light leakage.

[0022] Further, the laser irradiation position in S2 of the embodiment is obtained by a vision camera to obtain spatial coordinates, thereby guiding the welding head to move to the corresponding position to emit light to achieve paint removal and welding.

[0023] In order to test the welding strength of the welding product obtained according to the welding method of the embodiment and whether blackening phenomenon occurs, the following experiments can be carried out: Welding strength test: A tensile test is carried out using a tensile testing machine to test the tensile strength of the welded Pin needle and the enameled wire product. The water-based polyester-TiO2 composite paint, polyurethane-silane composite paint and polyimide-Al2O3 composite paint and pin needle are welded according to the welding method of the embodiment to obtain three products, respectively. The three products are fixed on the testing machine, a tensile force is applied at a certain tensile speed until the welded part breaks, and the tensile force value at the time of breakage is recorded. Each product is tested 20 times repeatedly, and the average tensile force value is calculated to evaluate the welding strength. At the same time, the condition of the broken part is observed to determine whether the welded part breaks or the enameled wire or Pin needle itself breaks, and the welding quality is further analyzed.

[0024] In the above 20 repeated tests, the average tensile force value of the welded part of the three welding products is higher than 80% of the strength of the enameled wire itself, proving that the welding strength has excellent consistency; and all sample breakages occur at the enameled wire body or Pin needle substrate, and the welding interface has no breakage phenomenon. Metallographic microscope observation shows that the welding fusion zone width is uniform, and there are no un-fusion, pores or crack defects.

[0025] Blackening phenomenon detection: a method combining visual inspection and microscopic observation. First, visually observe the appearance of the welded three products to see if there is obvious blackening phenomenon. The final test result is that the visual observation of the welded area of the three products shows no visible blackening, discoloration or carbonization marks, and the three welded products meet the appearance requirements of high reliability electronic components. The implementation principle of the embodiment is that the welding method of the embodiment combines specific winding methods, short wavelength laser, specific pulse waveform, mixed gas protection, plasma pretreatment and reasonable laser parameter settings and other links. The specific winding method makes the enameled wire and the pin needle closely combined, providing a good foundation for subsequent welding. The short wavelength laser can efficiently remove the paint under the specific pulse waveform, reducing the damage to the wire and avoiding the damage to the internal structure of the wire by the traditional mechanical stripping method. Mixed gas protection and plasma pretreatment can prevent oxidation and other problems during welding, improving the welding quality. Reasonable laser parameter settings, such as spot diameter, defocusing amount, laser beam and pin needle angle, are suitable for the welding of three types of enameled wire, such as water-based polyester-TiO2 composite paint, polyurethane-silane composite paint and polyimide-Al2O3 composite paint, and pin needle, and the three types of enameled wire have good welding effect, improving the welding efficiency and reducing the generation of welding defects.

[0026] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for soldering a pin to an enameled wire, characterized in that, Includes the following steps: S1: Wrap the enameled wire tightly around the surface of the pin to form a wound pin. The gap between the top two loops is ≤0.2mm. The top two loops and the loops below should have sufficient gaps, with a gap of ≥0.2mm. The distance from the topmost loop of wire to the top of the pin is ≤5 times the maximum side length of the pin. S2: Use a short-wavelength laser with a wavelength <600nm for irradiation. The distance from the center of the laser spot to the top enameled wire is less than twice the side length of the pin, and the distance from the center of the laser spot to the top enameled wire is greater than half the diameter of the laser spot. The welding power is 50~500W, and the welding time is 50~1000ms. The pin at the top of the enameled wire is completely melted, and the enameled wire is partially melted. The mixed melt of the two melts wraps around the unmelted enameled wire, cools and solidifies to form a molten ball, and the product is obtained by welding the pin and the enameled wire.

2. The method for welding a pin to an enameled wire according to claim 1, characterized in that, The short-wavelength laser is either 532nm green light or 450nm blue light.

3. The method for welding a pin to an enameled wire according to claim 1, characterized in that, In S2, paint is removed before welding using an asymmetric bipolar pulse waveform with a leading edge power of 800-1500W and a duration of 100-500ns; a trailing edge power of 300-600W and a duration of 500-1500ns; and a total energy density of 3-6J / cm².

4. The method for welding a pin to an enameled wire according to claim 3, characterized in that, After removing the paint, the product is pretreated with plasma in a protective gas environment and then welded to obtain the final product.

5. The method for welding a pin to an enameled wire according to claim 4, characterized in that, The flow rate of the protective gas is 5~30m / s.

6. The method for welding a pin to an enameled wire according to claim 4, characterized in that, The protective gas is a mixture of argon and hydrogen in a ratio of 8-9:1-2.

7. The method for welding a pin to an enameled wire according to claim 4, characterized in that, The laser defocusing amount during the paint removal process of S2 is ≤±5mm, and the laser defocusing amount during the welding process of S2 is ±3mm.

8. The method for welding a pin to an enameled wire according to claim 1, characterized in that, The angle between the laser beam of S2 and the pin is 10-75°.

9. The method for welding a pin to an enameled wire according to claim 1, characterized in that, In step S2, a light shield is placed near the pin to prevent reflections and light leakage from burning the soldered product.

10. The method for welding a pin to an enameled wire according to claim 9, characterized in that, In S2, the spatial coordinates of the laser irradiation position are obtained by a vision camera, which guides the welding head to move to the corresponding position for laser welding.