Connectors are mated by a male end and a female end, and can transmit information or current after release. In many electronic industries, smart manufacturing industries, and automotive industries, there are more and more application scenarios for connectors. Mainly due to the iterative research and development of intelligent manufacturing and automation equipment, in order to enable rapid assembly and production line assembly to implement modular combinations, and at the same time to facilitate maintenance and replacement, there are more and more scenarios where connectors are used.
Classification Of Connectors
The linker can be divided into flexible circuit board FPC connector, hard disk USB connection machine, high-definition media HMI connector, sensor RJ45 connector, VGA terminal D-sub connector, card card connector, display LCD-CONNE connector, battery connection Connectors, automotive connectors, etc. In the future, with the rapid development of Industry 4.0 and intelligent robots, the precision of connectors, the amount of data networking, and the number of pins will all grow by leaps and bounds.
(1) Wiring terminal
Terminals are mainly produced to facilitate the connection of wires. In reality, a terminal block is a piece of metal encased in insulating plastic. Both ends of the sheet metal have holes for inserting wires. There are screws for fastening or loosening. Sometimes two wires need to be connected, and sometimes they need to be disconnected. At this time, it can be connected with terminals, and it can be disconnected at any time without welding or tangling, which is convenient and quick. There are many types of terminals, commonly used are plug-in terminals, PCB terminal blocks, terminal blocks, screw-on terminal blocks, grid plate terminal blocks, etc.
Terminal features: various pin spacing, flexible wiring, suitable for high-density wiring requirements; the maximum current of the terminal is up to 520 A; suitable for SMT production process; can be used for reflow soldering, the maximum temperature resistance is 300 ℃; Accessory extensions.
(2) Audio/Video Connector
- ① Two-pin and three-pin plug sockets: mainly used for signal transmission between various devices, and the input plug is used as the input signal of the microphone. The two-pin plug and socket is mainly used for the connection of monophonic signals, and the three-pin plug and socket is mainly used for the connection of stereo signals. According to its diameter, it is divided into three types: 2.5 mm, 3.5 mm and 6.5 mm.
- ② Lotus plug and socket: mainly used for audio equipment and video equipment, and used as an input and output plug for the line between the two.
- ③ XLR plug (XLR): Mainly used for the connection between the microphone and the power amplifier.
- ④Five-core socket (DIN): mainly used for the connection between the cassette recorder and the power amplifier. It can concentrate stereo input and output signals on one socket.
- ⑤RCA plug: RCA plug is mainly used for signal transmission.
(3) Rectangular connector
Rectangular plug sockets are made of different numbers of contact pairs in a rectangular plastic shell with good insulation properties. The number of contact pairs in the plug socket is different, up to dozens of pairs. Arrangement, there are two rows, three rows, four rows and so on. Due to the elastic deformation of each contact pair, the generated normal pressure and friction can ensure good contact of the contact pair. For improved performance, some contact pairs are plated with gold or silver.
Rectangular plug sockets can be divided into pin type and hyperbolic spring type; with shell and without shell; there are locking type and non-locking type, this kind of connector is often used in low-frequency low-voltage circuits, high-low frequency mixed circuits, and is mostly used in radio instruments .
(4) Circular connector
There are two main types of circular connectors: plug-in and screw-on. The plug-in type is usually used for circuit connections with frequent plugging and unplugging, few connection points, and current less than 1A. Screw-on connectors are commonly known as aviation plugs and sockets. With a standard rotary locking mechanism, it is more convenient to connect in the case of multi-contact and large plug-in force, and has excellent anti-vibration performance; at the same time, it is also easy to achieve special requirements such as waterproof sealing and electric field shielding, and is suitable for applications that do not require frequent plug-in and pull-out high current circuit connections. The number of contacts for this type of connection ranges from 2 to nearly 100, the current rating ranges from 1 to hundreds of amps, and the operating voltage ranges from 300 to 500 volts.
(5) PCB connectors
Printed board connectors are transitioned from rectangular connectors and should belong to the category of rectangular connectors, but are generally listed separately as new connectors. The contact points vary from one to dozens, and can be used with strip connectors or directly with circuit boards, and are widely used in the connection of various boards and main boards in computer hosts. In order to connect reliably, the contacts are generally gold-plated to enhance their reliability, commonly known as gold fingers.
(6) Other connectors
Other connectors include integrated circuit sockets, power plug sockets, fiber optic connectors, ribbon cable connectors, and more.
Analysis of connector product processing technology
Although the shape of the connector is different, the general connector machining technology is as follows:
Stamping → electroplating → plastic core injection molding → assembly → storage
Next, let’s get to the point, starting from stamping:
1. Stamping process
Punching → Bending → Deep drawing → Fine blanking → Partial forming
- Punching: the punching process of separating the copper strip, including punching, blanking, trimming, cutting, etc.;
- Bending: a stamping process that bends the material into a certain angle and shape along the bending line;
- Deep drawing: the stamping step of turning the flat plate into various open hollow parts, or further changing the shape and size of the hollow parts;
- Fine blanking: For products with high requirements for dimensional accuracy and surface brightness, the process of meeting the requirements of drawings through fine blanking dies;
2. Electroplating process
The electroplating process is divided into three methods: continuous plating, barrel plating and rack plating
Continuous plating: pre-treatment (feeding → degreasing → pickling) → electroplating (nickel plating, gold plating, tin-lead plating) → post-processing (receiving → drying → sealing → washing)
- Barrel plating: discharging → chemical degreasing → water washing → skin finishing → pickling → water washing → nickel plating → water washing → peroxalic acid → water washing → passivation → neutralization → water washing → sealing → water washing → water washing → drying → receiving
- Rack plating: hanging → dewaxing → cleaning → ultrasonic degreasing → cleaning → cathodic degreasing → cleaning → acid activation → cleaning → alkali activation → cleaning → alkali copper → cleaning → activation → cleaning → coke copper → cleaning → activation → cleaning → acid copper → cleaning → activation → cleaning → nickel plating → cleaning → activation → cleaning → passivation → pure water cleaning → drying → hanging
3. Rubber core injection molding process
Plastic particle pretreatment → injection molding → product deburring → send for assembly
- ①Material particle pretreatment: It is necessary to pretreat plastics and carry out drying treatment to ensure material quality and production efficiency;
- ②Injection molding: The pretreated plastic particles are placed in the injection machine, the plastic particles are melted by high pressure and injected into the mold, and after a period of cooling, the mold is opened to obtain connector products;
- ③Product deburring treatment: remove burrs, welding and other dull traces of connector products, thereby improving the quality and appearance of connected machine products.
4. Assembly process
Appearance inspection → material on-line → riveting → assembly → electrical testing of finished products → labeling → full inspection → packaging
Analysis of key points of electroplating and injection molding process
- Electroplating: It is a process of depositing a coating with a desired shape by electrolytic method. Its purpose is to change the surface characteristics, which can improve the appearance, corrosion resistance, wear resistance and other required properties. In addition to these functions, electroplating is also used to change dimensions; the electrolytic process is performed in a bath, which can consist of molten salts or different types of solutions.
- Ingredients of plating solution: main salt, conductive salt, PH buffer, wetting agent, anode dissolution accelerator, additives
- Factors of coating crystallization: impurity content of solution, stirring speed, PH value, current density
- Deposition process and principle: Formula E=E°+(0.059/n)log[Mn+], where E=electrolysis value of electrolytic cell, E°=standard point position; n=number of electrons, [Mn+] (nth power +) = concentration of metal examples.
- Chemical basis related to electroplating: Hydrochloric acid contains ferric chloride, which contains 37% hydrogen chloride. It is a strong acid and is widely used as an etchant in electroplating production. If sulfuric acid is used as the etchant, a sulfuric acid solution with a concentration of 96% and a specific gravity of 1.84 can be used. Because concentrated sulfuric acid has water absorption, it will release a large amount of heat during the water absorption process, and its volatility is low, so it can be heated to increase the etching speed. Nitric acid is also often used as an etchant in the electroplating industry. For the three methods of visual inspection, the one with white smoke is hydrochloric acid, the one with yellow smoke is nitric acid, and the one with no smoke is sulfuric acid.
For the solution in the process of compounding the etchant, the solution must be uniform, and the proportion of the solvent added to other materials must be appropriate, and the solute dissolved in the solvent must be cleaned regularly to ensure the concentration and solvent saturation in the solution, so as to ensure the concentration of the solution. established solubility.
For the prepared solvent, it is necessary to ensure its surface tension. When the gravitational force of the internal molecules of the liquid on the solvent liquid is greater than the gravitational force of the gas molecules on him, the surface of the liquid shrinks and forms surface tension. Therefore, the nature, temperature, and concentration of the solution will affect the solvent. surface tension. In order to maintain a good effect, it is necessary to add a surfactant. An anionic type, such as soap, sodium lauryl sulfate, sodium dodecyl sulfate, etc., can be added according to the actual production situation, and a cationic type, such as fat Group amine salts, alkyl quaternary ammonium salts, alkyl pyrimidine halides. Therefore, in the electroplating process, a large amount of surfactants are used, which are mainly treated in the electroplating process to improve the cathode planning effect and improve the dispersion ability of the solution.