Plug-in of electronic components
Plug-in of electronic components
Principle of component insertion
Manual insertion and welding should be first inserted into those components that need to be mechanically fixed,such as the power device radiator,bracket,clip,etc,and then insert the need to weld fixed components.Do not touch the device pins and the copper foil on the printed board directly.
Automatic mechanical equipment plug-in, welding,it should be first inserted in those highly low components,after the installation of those high level of components,valuable key components should be placed in the final plug,radiator,brackets,clips,etc,the plug should be close to the welding process.
metallized hole welding,more than two layers of printed circuit board holes are to be metalized.When welding,not only the solder wetting pad,but also wetting and filling the hole.Therefore,the heating time of the metallized hole should be longer than that of the single plate.
The welding process of printed circuit board
Before welding,be familiar with the assembly drawing of the printed circuit board, and check the components of the printed circuit board according to the drawing,does the specification and quantity meet the requirements.
The sequence of welding sequence components is resistor,capacitor, diode, three-plate tube integrated circuit,high-power tube,other components are first small and then large.
Requirements for welding of components 1 Welding of resistors.As shown in Figure 2-1 and 21,the resistor is accurately loaded to the specified position,and the tag is required to be upward,consistent with the word.Install a specification and then install another specification,as far as possible the height of the resistor is the same.The excess pins on the surface of the printed circuit board are cut off after welding.
Welding of Capacitor.The capacitor is required to be installed in accordance with the drawing requirements, and the " + " pole and " 1 " pole of the capacitor with polarity can not be connected to the wrong position.The direction of the marking on the capacitor is easy to see.First,glass glaze capacitor,metal film capacitor, ceramic capacitor,and finally electrolytic capacitor.
the welding of the diode.After correctly identifying the positive and negative electrodes, we should install the required positions according to the requirements,and the models and markings are easy to see.When welding a vertical diode,the time should not exceed 2S when welding the shortest pin.
the welding of the triode. According to the requirements, e,B and C three pins should be installed in the specified positions.The welding time should be as short as possible,and the tweezers should be used to clamp the pins when welding,so as to help the heat dissipation.When welding the high power triode, if you need to install the radiator,the contact surface should be smooth,smooth and then fastened.If the insulating film is required to be added,you must not forget to use plastic wires when the pins are connected to the solder joints on the circuit board.
the welding of integrated circuits. The integrated circuit is mounted on the printed circuit board,and according to the requirements of the drawings,check whether the model and pin location of the integrated circuit meet the requirements.When welding,the two pins on the edge of the integrated circuit are first welded to position them and then welded from left to right or from top to bottom.When welding,the amount of soldering iron is the only amount of 2~3 pin,and the soldering iron head contact with the copper foil of the printed circuit first.When the soldering tin enters the bottom of the pin of the integrated circuit,the iron head is contacted to the pin,and the contact time is not more than 3S.After the welding to check, whether there is leakage welding,touch welding,virtual welding,and clean the solder joints.Welding methods in the production of electronic industry.In the mass production enterprises of electronic products, the welding of printed circuit board mainly adopts dip welding,wave soldering and back-flow welding.