A processing method for 0.28mm elastic stranded wire pins of ultra-micro rectangular electrical connector

Abstract

The present invention provides a processing method for 0.28mm elastic twisted wire pins of ultra-micro rectangular electrical connectors, characterized in that it includes the following steps: step 1, cleaning and degreasing copper wires, pre-plating copper wires, twisting wires, and straightening processes; step 2, laser cutting and laser welding processes; step 3, waisting, shaping, selection, cleaning and degreasing, and aging processes; step 4, gold plating and post-plating inspection processes; step 5, appearance inspection processes; step 6, plug-in and pull-out force testing, selection, and inspection warehousing processes. The present invention can be applied to the processing of 0.28mm elastic twisted wire pins of ultra-micro rectangular electrical connectors with a contact spacing of 0.635mm, solves the problems of collapse, wrinkles, and deformation of needle welding points, and significantly improves the quality of needle surface coating. The needle welding points processed by the process method of the present invention are full, round and smooth, the coating is continuous, dense and bright, and the nitric acid corrosion resistance is improved from the original state of 5min to 17min, which can meet the environmental resistance requirements of fluorine-containing wires used in aerospace.

Description

Technical Field

[0001] The invention relates to a processing method for an elastic twisted wire pin, in particular to a processing method for an ultra-micro rectangular electrical connector 0.28 mm elastic twisted wire pin. Background Art

[0002] In traditional electrical connectors, the sockets are usually elastic parts. With the requirement of miniaturization of electrical connectors, the elastic sockets can no longer be miniaturized further and cannot meet the needs of connector miniaturization and high density. With the emergence of elastic twisted wire pins, this fatal weakness has been completely overcome. Connectors using elastic twisted wire pins (commonly known as twisted pins) are called micro-rectangular electrical connectors. The elastic twisted wire pins are composed of 3 copper wires as the inner ring and 7 beryllium bronze wires as the outer ring. The inner and outer rings are twisted together in reverse. Its structural characteristics give it good elasticity, contact performance and seismic resistance. The structural model is shown in the attached figure. Figure 1 shown.

[0003] At present, the commonly used micro rectangular electrical connectors in aerospace are mainly CDb series, J29 series, J24 series, and J30 series, with a contact pitch of 1.91 to 1.27 mm. With the development of miniaturization of aerospace product structure, the installation space of electrical connectors has been tightened, and the space available for laying cable assemblies has become increasingly limited. AIRBORN's NM and NK series ultra-micro rectangular electrical connectors with a contact pitch of 0.635 mm can hold 1,600 contacts per square inch, which can save more board space. Therefore, they are gradually widely used in aerospace. Compared with the micro rectangular electrical connector with a contact pitch of 1.27 mm, the diameter of its elastic stranded wire pin has been reduced by half, from 0.56 mm to 0.28 mm. When the ultra-micro rectangular electrical connectors processed based on the traditional elastic stranded wire pin manufacturing process in China were undergoing aerospace-grade product certification, it was found that the 0.28 mm elastic stranded wire pins of the ultra-micro rectangular electrical connectors with wires had black needles after being stored in a closed container for a certain period of time, and some contacts had scattered wires. Typical morphology photos are attached Figure 2 After analyzing the composition of the black corrosion product, the fluorine element reached 25%. After rechecking the ultra-micro rectangular electrical connector without wires, it was found that the 0.28mm elastic stranded wire pin processed by the traditional elastic stranded wire pin manufacturing process had a needle head weld point that was not full and round, but had obvious wrinkles. The typical morphology is shown in the attached figure. Figure 3 .

[0004] Since aerospace products have very strict requirements on radiation indicators, spacecraft usually use C55 / series cross-linked ethylene-tetrafluoroethylene wire for the production of wired connectors, with a radiation resistance index of 5×108rad. However, C55 fluorine-containing wire for aerospace will release trace amounts of corrosive F, and has very high requirements on the quality of contact plating. The elastic stranded wire pins made by traditional elastic stranded wire pin technology have incomplete needle solder joints and insufficient strength, which leads to poor surface plating quality and ultimately causes F corrosion. Therefore, it is urgent to improve the traditional elastic stranded wire pin manufacturing process and form a processing method that can meet the surface plating quality of 0.28mm elastic stranded wire pins of ultra-micro rectangular electrical connectors. Summary of the invention

[0005] In order to solve the above technical problems, the present invention finds out the shortcomings of the traditional elastic stranded wire pin manufacturing process and improves it, thereby providing a processing method for improving the surface plating quality of 0.28mm elastic stranded wire pins and improving the quality assurance requirements, mainly in three aspects: 0.28mm elastic stranded wire pin preparation, electroplating pre-treatment and appearance inspection.

[0006] Specifically, the present invention provides a processing method for a 0.28 mm elastic stranded wire pin of an ultra-micro rectangular electrical connector, characterized in that it comprises the following steps:

[0007] Step 1: Clean and degrease the copper wire, pre-plate the copper wire, twist the wire, and straighten the wire;

[0008] Step 2: Perform laser cutting and laser welding processes;

[0009] Step 3: Carry out waist bulging, shaping, selection, cleaning, degreasing and aging processes;

[0010] Step 4: Perform gold plating and post-plating inspection process;

[0011] Step 5: Check the appearance process;

[0012] Step 6: Carry out plug-in and pull-out force testing, selection and inspection before warehousing.

[0013] Furthermore, in step 2, the laser welding power is 2.1 kW to 2.6 kW.

[0014] Furthermore, in step 2, inert gas protection is introduced.

[0015] Furthermore, in step 2, laser cutting and laser welding are performed simultaneously in situ.

[0016] Furthermore, before step 4, a pickling and activation process is added.

[0017] Furthermore, the pickling and activation process includes immersing all 0.28 mm elastic stranded wire pins to be electroplated in 20% dilute sulfuric acid and continuously stirring and cleaning for 60 minutes.

[0018] Furthermore, in step 4, the post-plating inspection includes an acid resistance test and a coating thickness test.

[0019] Furthermore, in step five, an appearance inspection is performed according to the technical requirements of the visualized 0.28 mm elastic stranded wire pin process.

[0020] Furthermore, the visual inspection magnification is required to be 200 times.

[0021] Furthermore, the diameter of the elastic twisted wire pin of the ultra-micro rectangular electrical connector is 0.28 mm, and the elastic twisted wire pin is formed by 3 copper wires as an inner ring and 7 beryllium copper wires as an outer ring, and the inner and outer rings are twisted together in reverse.

[0022] The present invention provides a process method for elastic twisted wire pins, which can be applied to the processing of 0.28mm elastic twisted wire pins of ultra-micro rectangular electrical connectors with 0.635mm contact spacing. At present, there is no report on the process method for 0.28mm elastic twisted wire pins in China. The ultra-micro rectangular electrical connectors with 0.635mm contact spacing abroad use cage-type elastic pins with different process routes. The present invention improves the traditional elastic twisted wire pin manufacturing process, solves the problems of collapse, wrinkles and deformation of the weld point of the 0.28mm elastic twisted wire pin needle, and significantly improves the quality of the needle surface coating. The weld point of the 0.28mm elastic twisted wire pin needle processed by the process method of the present invention is full, round and smooth, the coating is continuous, dense and bright, and the nitric acid corrosion resistance is improved from 5min in the original state to 17min, which can meet the environmental resistance requirements of fluorine-containing wires used in aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the structural model diagram of the 0.28mm elastic stranded wire pin;

[0024] Figure 2 This is the corrosion morphology of the 0.28mm elastic stranded wire pin in the prior art;

[0025] Figure 3 It is the typical appearance of the uncorroded 0.28mm elastic stranded wire pin in the prior art;

[0026] Figure 4 It is a flow chart of the processing method of the ultra-micro rectangular electrical connector 0.28mm elastic stranded wire pin of the present invention;

[0027] Figure 5 This is a typical appearance of a 0.28 mm elastic stranded wire pin obtained by combining laser welding with laser cutting process in the present invention;

[0028] Figure 6 This is a typical morphology of a 0.28 mm elastic stranded wire pin obtained by introducing inert gas protection during laser cutting and welding of the present invention;

[0029] Figure 7 This is the typical morphology of a 0.28 mm elastic stranded wire pin obtained by adding a special pickling and activation process before electroplating in the present invention;

[0030] Figure 8 This is an example of visualizing the process technology requirements for 0.28mm flexible stranded wire pins. DETAILED DESCRIPTION

[0031] The present invention provides a processing method for a 0.28 mm elastic stranded wire pin of an ultra-micro rectangular electrical connector. In order to make the purpose and features of the present invention more obvious and easy to understand, the following is a processing method for a 0.28 mm elastic stranded wire pin of an ultra-micro rectangular electrical connector. Figures 1 to 8 The specific embodiments of the present invention are described in further detail.

[0032] As mentioned earlier, Figure 1 This is the structural model diagram of the 0.28mm elastic stranded wire pin. Figure 1 The 0.28mm elastic stranded wire pins shown are Figure 2 , Figure 3 Defects shown. Figure 2 The corrosion morphology of the 0.28 mm elastic stranded wire pin in the prior art is shown in FIG. Figure 2 As shown, the pin head is black and has some loose threads. Figure 3 This is the typical appearance of a 0.28mm elastic stranded wire pin that is not corroded in the prior art. Figure 3 As shown, the surface of the needle welding point of the 0.28mm elastic stranded wire pin is not full and round, but has obvious wrinkles. In view of the above defects, the inventors have found out the shortcomings of the traditional elastic stranded wire pin manufacturing process and improved it, thereby providing a processing method that improves the surface plating quality of the 0.28mm elastic stranded wire pin and improves the quality assurance requirements. The present invention mainly improves the 0.28mm elastic stranded wire pin preparation, electroplating pre-treatment and appearance inspection in three aspects.

[0033] On the one hand, the inventors found that the existing elastic stranded wire pin manufacturing process uses mechanical cutting followed by laser welding. Cutting and welding are independent processes. After the wire harness is mechanically cut, it needs to be clamped again before laser welding can be performed. Cutting and welding are not synchronized, resulting in deformation and unevenness of the cut end faces of the stranded wire harness, causing the welds to be incomplete and the surface to be rough after welding of the elastic stranded wire pins. Based on the above understanding, the present invention introduces laser cutting for the processing of 0.28mm elastic stranded wire pins, and simultaneously combines the laser cutting and laser welding processes. As a result, the present invention eliminates secondary clamping, synchronizes cutting and welding, and improves the fullness of the needle tip after welding.

[0034] On the other hand, the inventors found that the 0.28mm elastic stranded wire pin is smaller in size and is more susceptible to the high temperature generated by laser cutting and welding, which causes large-area oxidation on the surface of the welding needle head, making it difficult to thoroughly clean the subsequent process, thereby affecting the electroplating quality. Based on the above understanding, the present invention adopts the airtight modification of the cutting and welding equipment, introduces the inert gas filling equipment, and performs inert gas protection when the elastic stranded wire pin is cut and welded, thereby reducing the high-temperature oxidation degree of the elastic stranded wire pin head.

[0035] On the other hand, the inventors found that after the 0.28mm elastic stranded wire pin was electroplated according to the original electroplating process, there were still a small amount of pinholes around the pin that were not covered with gold layer, which affected the environmental resistance of the elastic stranded wire pin. Based on the above understanding, the present invention aims at the insufficient pickling and activation strength of the original electroplating process, and the incomplete removal of the oxide layer of the pin. Before entering the existing electroplating process of the elastic stranded wire pin, a special pickling and activation process is added to strongly remove the oxide layer around the pin surface.

[0036] On the other hand, the present invention strengthens the quality inspection of the elastic stranded wire pins after electroplating, adopts the visualized process technology requirements of the elastic stranded wire pins, strictly eliminates unqualified products with abnormal plating and morphology, and ensures the reliability of each elastic stranded wire pin.

[0037] Figure 4 The flowchart of the processing method of the ultra-micro rectangular electrical connector 0.28mm elastic stranded wire pin of the present invention. Figure 4 As shown, the present invention is based on the existing elastic stranded wire pin processing technology, aims at the smaller size of 0.28mm elastic stranded wire pin, optimizes and improves some of the original processes, and adaptively adds processes to achieve it.

[0038] Specifically, the processing method of the ultra-micro rectangular electrical connector 0.28 mm elastic stranded wire pin of the present invention comprises the following steps:

[0039] Step 1: Clean and degrease the copper wire, pre-plate the copper wire, twist the wire, and straighten the wire.

[0040] This process can be carried out according to the existing elastic stranded wire pin processing technology.

[0041] Step 2: Perform laser cutting and laser welding processes, with the laser welding power being 2.1 kW to 2.6 kW.

[0042] In order to eliminate the deformation and unevenness of the cut end face of the stranded wire harness caused by secondary clamping, which causes the incomplete solder joints and rough surface of the elastic stranded wire pin needle after fusion welding, laser cutting is introduced to replace the original mechanical cutting, and the equipment is modified to merge the laser cutting and laser welding processes, and the laser fusion welding power is increased from 0.4kW to 0.8kW to 2.1kW to 2.6kW. After the process merger and process parameter adjustment, the fullness of the 0.28mm elastic stranded wire pin needle is significantly improved. Laser cutting and laser welding are preferably performed simultaneously in situ, that is, without moving the wire harness. Figure 5 This is a typical morphology of a 0.28 mm elastic stranded wire pin obtained by combining laser welding and laser cutting processes in the present invention. The improved typical morphology is shown in the following figure. Figure 5 shown.

[0043] Preferably, an inert gas shield is introduced when the elastic stranded wire pin is cut off and welded.

[0044] In order to reduce the problem of large-area oxidation on the surface of the 0.28mm elastic stranded wire pin caused by the high temperature generated by laser cutting and fusion welding, the laser cutting and welding equipment environment is optimized, the cutting and fusion welding equipment is modified to be airtight, and inert gas nitrogen filling equipment is introduced. When the elastic stranded wire pin is cut and fusion welded, inert gas protection is introduced. The high-temperature oxidation on the surface of the fusion welding point of the 0.28mm elastic stranded wire pin needle is significantly improved after processing. Figure 6 This is the typical morphology of the 0.28 mm elastic stranded wire pin obtained by introducing inert gas protection during laser cutting and welding of the present invention. The typical morphology after improvement is shown in FIG. Figure 6 .

[0045] Step three: carry out the processes of bulging, shaping, selecting, cleaning, degreasing and aging.

[0046] This process can be carried out according to the existing elastic stranded wire pin processing technology.

[0047] Step 4: Perform gold plating and post-plating inspection process.

[0048] This process can also be carried out according to the existing elastic stranded wire pin processing process. The post-plating inspection process usually includes acid resistance test and coating thickness test.

[0049] Preferably, before electroplating the 0.28 mm elastic stranded wire pins, an acid cleaning and activation process is added. The acid cleaning and activation process can be to immerse all the 0.28 mm elastic stranded wire pins to be electroplated in 20% dilute sulfuric acid and continuously stir and clean for 60 minutes. Figure 7 This is the typical morphology of the 0.28mm elastic stranded wire pin obtained by adding a special pickling and activation process before electroplating. The 0.28mm elastic stranded wire pin needle head processed by the enhanced pickling and activation process has a smooth surface without pinholes and other small defects. The typical morphology photo is shown in Figure 7 .

[0050] Step 5: Check the appearance.

[0051] Preferably, the appearance inspection is carried out according to the technical requirements of the visualized 0.28 mm elastic stranded wire insertion process. Figure 8 This is an example of visualizing the process technology requirements for 0.28mm elastic stranded wire pins. At the same time, the appearance inspection multiple requirement is preferably increased from the current 40 times to 200 times, thereby further strengthening the inspection of the shape, fullness and electroplating quality of the solder joints of the 0.28mm elastic stranded wire pins;

[0052] Step 6: Insertion and extraction force testing, selection and inspection for warehousing.

[0053] This process can be carried out according to the existing elastic stranded wire pin processing technology.

[0054] The present invention provides a process method for elastic twisted wire pins, which can be applied to the processing of 0.28mm elastic twisted wire pins in ultra-micro rectangular electrical connectors with a contact spacing of 0.635mm. Currently, there are no reports on the process method for 0.28mm elastic twisted wire pins in China. Foreign ultra-micro rectangular electrical connectors with a contact spacing of 0.635mm use cage-type elastic pins, which have different process routes. The present invention solves the problems of collapse, wrinkles and deformation of the weld points of the needles of 0.28mm elastic twisted wire pins by improving the traditional manufacturing process of elastic twisted wire pins, and significantly improves the quality of the surface coating of the needles. The weld points of the needles of 0.28mm elastic twisted wire pins processed by the process method of the present invention are full, round and smooth, the coating is continuous, dense and bright, and the corrosion resistance to nitric acid is improved from 5min in the original state to 17min, which can meet the environmental resistance requirements of fluorine-containing wires used in aerospace.

[0055] It should be noted that the above is only an illustrative description and explanation of the present invention, and those skilled in the art should understand that any modification and replacement of the present invention belongs to the protection scope of the present invention.

Claims

1. A processing method for a 0.28mm elastic stranded wire pin of an ultra-micro rectangular electrical connector, characterized in that: The diameter of the elastic twisted wire pin of the ultra-micro rectangular electrical connector is 0.28 mm. The elastic twisted wire pin is formed by 3 copper wires as inner rings and 7 beryllium copper wires as outer rings, and the inner and outer rings are twisted together in reverse. The processing method includes the following steps: Step 1: Clean and degrease the copper wire, pre-plate the copper wire, twist the wire, and straighten the wire; Step 2: Perform laser cutting and laser welding processes. In step 2, inert gas protection is introduced, the laser welding power is 2.1kW to 2.6kW, and laser cutting and laser welding are performed simultaneously in situ; Step 3: Carry out waist bulging, shaping, selection, cleaning, degreasing and aging processes; Step 4: Perform gold plating and post-plating inspection. Before step 4, add an acid pickling and activation process; Step 5: Check the appearance process; Step 6: Carry out plug-in and pull-out force testing, selection and inspection before warehousing.

2. The processing method of the ultra-micro rectangular electrical connector 0.28 mm elastic stranded wire pin according to claim 1 is characterized in that: The pickling and activation process includes immersing all 0.28 mm elastic stranded wire pins to be electroplated in 20% dilute sulfuric acid and continuously stirring and cleaning for 60 minutes.

3. The processing method of the ultra-micro rectangular electrical connector 0.28 mm elastic stranded wire pin according to claim 1 is characterized in that: In step 4, the post-plating inspection includes an acid resistance test and a coating thickness test.

4. The processing method of the ultra-micro rectangular electrical connector 0.28 mm elastic stranded wire pin according to claim 1 is characterized in that: In step five, an appearance inspection is performed in accordance with the visual 0.28mm elastic stranded wire pin process technical requirements.

5. The processing method of the ultra-micro rectangular electrical connector 0.28 mm elastic stranded wire pin according to claim 4 is characterized in that: The visual inspection magnification requirement is 200 times.

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