How to solve the problem of soldering through tin in PCBA?
2022-12-16
Tin penetration rate is very important in wave soldering process of PCBA through-hole components. Whether tin penetration is good directly affects the reliability of solder joints. If the tin penetration effect is not good after wave soldering, it is easy to cause problems such as virtual welding.
Solder penetration rate requirements for wave soldering:
The tin penetration rate of wave solder joints should generally reach more than 75%, that is, the tin penetration rate of panel appearance inspection is higher than 75% of the plate thickness, and the tin penetration rate can be 75%-100%. The heat of wave soldering is absorbed quickly by PCB board during welding. If the temperature is not enough, there will be bad tin penetration. In order to make the PCB board get more heat, you can adjust the corresponding tin depth according to different PCB boards.
Factors affecting tin penetration rate of wave soldering:
The bad solder penetration is mainly related to raw materials (PCB board, components >, soldering process, flux use and manual welding level.
Raw material factor:
Under normal circumstances, tin has a strong permeability, but not all metals can penetrate, such as aluminum, aluminum metal surface will form a dense protective layer, its molecular structure is difficult for other molecules to penetrate. In addition, if there is oxidation on the surface of the metal, tin is also difficult to penetrate, need to use flux treatment, or clean the oxide layer.
Wave soldering process factors:
Poor tin penetration is closely related to the wave soldering process, so it is necessary to reset and optimize the welding parameters, such as wave height, temperature setting, welding time and moving speed, etc. The track Angle can be appropriately reduced to increase the height of the wave peak and improve the contact surface between the tin liquid and the pad; Then appropriately adjust the temperature of the wave peak welding, the higher the welding temperature, the stronger the permeability of tin, but the welding temperature should be within the temperature range of the components; Finally, the transportation speed can be reduced, the preheating and welding time can be increased, so that the flux can fully remove the surface oxide, penetrate the solder joint, and improve the tin penetration rate.
Flux factor:
Surface oxide, and prevent re-oxidation during the welding process, improper selection of flux, uneven spraying, too little use will lead to poor tin. First of all, we should choose a regular brand of flux, the effect will be better, in addition to regularly check the flux nozzle, to prevent the nozzle blockage or damage.
Manual welding factors:
In the welding quality inspection of wave soldering, some components only form a conical surface solder joint, but there is no through-tin in the through-hole, forming a virtual welding. Similar problems generally appear in manual welding, mainly because the welding temperature is not enough or the welding time is too short. Poor solder penetration in wave soldering is easy to cause false soldering, which increases the cost of manual repair. The tin penetration rate of selective wave soldering is much better than that of wave soldering. If the product has high requirements on welding quality and tin penetration rate, selective soldering can be used to reduce the problem of poor tin penetration to a certain extent.
Solder penetration rate requirements for wave soldering:
The tin penetration rate of wave solder joints should generally reach more than 75%, that is, the tin penetration rate of panel appearance inspection is higher than 75% of the plate thickness, and the tin penetration rate can be 75%-100%. The heat of wave soldering is absorbed quickly by PCB board during welding. If the temperature is not enough, there will be bad tin penetration. In order to make the PCB board get more heat, you can adjust the corresponding tin depth according to different PCB boards.
Factors affecting tin penetration rate of wave soldering:
The bad solder penetration is mainly related to raw materials (PCB board, components >, soldering process, flux use and manual welding level.
Raw material factor:
Under normal circumstances, tin has a strong permeability, but not all metals can penetrate, such as aluminum, aluminum metal surface will form a dense protective layer, its molecular structure is difficult for other molecules to penetrate. In addition, if there is oxidation on the surface of the metal, tin is also difficult to penetrate, need to use flux treatment, or clean the oxide layer.
Wave soldering process factors:
Poor tin penetration is closely related to the wave soldering process, so it is necessary to reset and optimize the welding parameters, such as wave height, temperature setting, welding time and moving speed, etc. The track Angle can be appropriately reduced to increase the height of the wave peak and improve the contact surface between the tin liquid and the pad; Then appropriately adjust the temperature of the wave peak welding, the higher the welding temperature, the stronger the permeability of tin, but the welding temperature should be within the temperature range of the components; Finally, the transportation speed can be reduced, the preheating and welding time can be increased, so that the flux can fully remove the surface oxide, penetrate the solder joint, and improve the tin penetration rate.
Flux factor:
Surface oxide, and prevent re-oxidation during the welding process, improper selection of flux, uneven spraying, too little use will lead to poor tin. First of all, we should choose a regular brand of flux, the effect will be better, in addition to regularly check the flux nozzle, to prevent the nozzle blockage or damage.
Manual welding factors:
In the welding quality inspection of wave soldering, some components only form a conical surface solder joint, but there is no through-tin in the through-hole, forming a virtual welding. Similar problems generally appear in manual welding, mainly because the welding temperature is not enough or the welding time is too short. Poor solder penetration in wave soldering is easy to cause false soldering, which increases the cost of manual repair. The tin penetration rate of selective wave soldering is much better than that of wave soldering. If the product has high requirements on welding quality and tin penetration rate, selective soldering can be used to reduce the problem of poor tin penetration to a certain extent.
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