Manual welding process standard
1. Purpose
Standardize the manual welding operation in the processing of products to ensure product quality.
2. Scope of application
Production workshop (SMT and post-welding).
3. Tools and requirements for manual welding
3.1 Soldering iron
3.1.1 The electric soldering iron used for manual soldering needs to be equipped with an anti-static grounding wire. The grounding wire must be reliably grounded during welding, and the grounding end of the anti-static constant temperature electric soldering iron plug must be reliably connected to the AC power protection ground.
3.1.2 The insulation resistance of the electric soldering iron should be greater than 10MΩ, and the insulation layer of the power cord must not be damaged.
3.1.3 Put the multimeter on the resistance gear, and the test leads respectively touch the tip of the soldering iron and the grounding terminal of the power plug. The grounding resistance value should be less than 3Ω when the grounding resistance is stable; otherwise, the grounding is not good.
3.1.4 The tip of the soldering iron must not have defects such as oxidation, ablation, deformation, etc.
3.2 Soldering iron stand
3.2.1 After the soldering iron is put into the soldering iron bracket, it should be able to maintain stability without sagging, and the retaining ring can cover all the heating parts of the soldering iron.
3.2.2 Add appropriate amount of water to the cleaning sponge on the bracket to make the sponge moist and not dripping.
3.3 Tweezers: The port is well closed, and the tips of the tweezers are not twisted or broken.
3.4 Anti-static wrist: The test is qualified, the wrist strap is moderately tight, the metal sheet fits well with the wrist skin, and the grounding wire is connected reliably.
3.5 When the soldering iron is not in use, it must be tinned for protection. If it is not used for a long time during working hours, the power must be turned off to prevent empty burning. After get off work, the power must be unplugged.
4. Applicable process
Leaded process, lead-free process
5. Preparation for manual welding
5.1 Ensure that welding personnel wear anti-static wrists, and confirm that the hot soldering iron is grounded.
5.2 Check whether the heating of the soldering iron is normal, whether the tip of the soldering iron is oxidized or has dirt, if so, wipe off the dirt with a wet sponge, and the tip of the soldering iron should be covered with a layer of bright solder before welding.
5.3 Check whether the temperature of the soldering iron tip meets the requirements of the components to be soldered. Every time you turn on the soldering iron and adjust the temperature of the soldering iron, you must conduct a temperature test and make a record; the temperature requirements of the soldering iron are as follows
5.4 Check the leakage voltage of the soldering iron, test the voltage between the soldering iron tip and the ground wire with the AC gear of a multimeter, and make a record. It must be less than 5V, otherwise it cannot be used.
6. Manual welding requirements (temperature requirements)
6.1 General requirements for manual welding:
6.1.1 Leaded process
The temperature of leaded constant temperature soldering iron is generally controlled between 280~360°C, the default setting is 330±10°C, and the soldering time is less than 3 seconds. When soldering, the tip of the soldering iron is in contact with the pad and the component pin at the same time, and after heating, the tin wire is sent for welding. Special welding requirements for some components:
6.1.1.1, SMD devices
6.1.1.1.1 The temperature of the soldering iron tip during soldering is: 320±10°C
Welding time: 1~3 seconds for each solder joint
Soldering iron tip temperature when removing components: 310~350°C
Note: Please use different soldering tips according to the size of the CHIP.
6.1.1.2, DIP device
6.1.1.2.1 The temperature of the soldering iron tip during soldering is: 330±5°C
Welding time: 2~3 seconds
Note: When welding high power (TO-220, TO-247, TO-264 and other packages) or the solder joint is connected with a large copper foil, when the above temperature cannot be soldered, the temperature of the soldering iron can be raised to 360 ° C, when the soldering is sensitive to heat The temperature of parts (LED, CCD, sensor, etc.) is controlled at 260~300°C.
6.1.2 Lead-free process
The temperature of the lead-free constant temperature soldering iron is generally controlled between 340~380°C, the default setting is 360±10°C, and the soldering time is less than 3 seconds. It is required that the temperature of the soldering iron be returned to the set temperature every second. temperature.
