Smt processing technology and processing precautions

SMT processing technology and processing precautions
After using the SMT processing and welding procedure, the cleaning work will be carried out If the security of the SMT wiring program is processed after the smt processing procedure cannot be guaranteed after the test, it should be a strict standard Therefore, the type and characteristics of detergent shall be selected during cleaning, and the integrity and safety of equipment and process shall also be considered during cleaning
What is the surface mounting process for electronic parts?
1. Hardening and reflow
Hardening is the most important step for mounting the surface of electronic components, and its role is to accurately fix the components on PCB. Rearranging technology requires higher technology for the surface mounting process of electronic components, and is usually a skilled technician who can complete this task.
2. Printing and ignition adhesive

Printing and adhesive are devices used to print patches on PCB welding plates, which are used to prepare electronic components for welding. The solder paste printer at the front end of SMT is used for surface mounting of common electronic components. After smt processing, the adhesive is directly dropped into the fixed position of the PCB, and then the component is directly fixed on it, which will increase the service time of the component. At present, the most commonly used parts on the market are all manual adhesives.
3. Cleaning and Testing
These two steps can be said to be the last two steps in the surface mounting process of electronic parts. The cleaning process must also be careful, just as you know that cleaning is to remove the remaining useless items on the PCB, you can determine which positions are not fixed. This test requires more detailed operation (such as magnifying glass or test equipment), which is the most important step for surface mounting of electronic components and directly affects whether the PCB works normally.
This SMT processing technology is very complex Many people saw this opportunity, learned SMT processing technology and set up factories Especially in Shenzhen, where the electronic industry is very mature, SMT processing has formed an early scale industry
Precautions in smt processing
Surface mount processing technology is one of the basic components of electronic components. It is called external assembly technology, which is divided into lead-free leads and short leads. It is a circuit assembly technology that is assembled by welding and welding through technological process, and it is also the most popular technology in the electronic assembly industry.
In the electronic assembly industry, smt processing chip factories have smaller parts, so attention should be paid to welding matters when welding.
1. Several problems should be paid attention to when welding.
Generally speaking, the total welding time of welding points shall be controlled within 2~3s.
The dwell time between welding processes is very important to ensure the welding quality, which needs to be mastered slowly through practical operation.
After the welding operation, the solder paste can not be moved to change the position of the welded parts until the solder paste is completely cured.
2. Precautions for welding individual parts
The welding of a single part plays an important role in the whole electronic product. In addition to mastering the key points of welding operation, please also pay attention to the following points
(1) The electric soldering iron is generally internally heated (20~35W) or thermostatic, and the temperature should not exceed 300 ℃. Under normal conditions, select the small cone welding head.
(2) When heating, try to make the welding head contact the copper foil on the PCB and the pin of the part at the same time, and rotate around the bonding pad with a diameter of 5mm or more.
(3) When welding more than two layers of printed circuit boards, the pad holes should also be wetted and filled.
(4) After welding, cut off the excess pins and clean the PCB with cleaning solution.
(5) The most common electronic components on PCB are resistors, capacitors, inductors, diodes, etc. The patch welding methods of these components are basically the same.
3. Precautions when installing and welding integrated circuits
This method of inserting and consolidating integrated circuits is basically the same as that of individual components However, due to the large number of pins of integrated circuits, more attention should be paid to inserting or soldering integrated circuits Generally, the method of inserting an integrated circuit depends on the printed circuit board In order to better dissipate the integrated circuit, the integrated circuit socket is connected to the bottom of the integrated circuit, and the integrated circuit is fixed by the integrated circuit socket
The integrated circuit is highly integrated and easy to overheat. Because it cannot withstand temperatures above 200, full attention must be paid to welding. In addition to mastering the basic points of welding operation, special attention should be paid to the following points.
Do not use a knife to wipe the gold plated circuit pins used for smt processing. Wipe it with alcohol, or use the eraser on the picture.
Do not remove the preset short circuit before soldering CMOS circuits.
The welding time shall be as short as possible and shall not exceed 3s under normal conditions. (4) It is better to use iron with a constant temperature of 230 degrees.
Please conduct anti-static treatment on the workbench.
Select a narrow head to avoid touching adjacent ends during welding.
The safe welding sequence of pins is grounded output power input