PCBA chip processing factory improves PCBA welding method
1、 Improve welding temperature and time
The intermetallic bond between copper and tin forms grains, and the shape and size of the grains depend on the duration and strength of the temperature during welding. Less heat during welding can form fine crystalline structure and form excellent welding points with the best strength. PCBA chip processing reaction time is too long, whether due to long welding time, high temperature or both, will lead to rough crystalline structure, which is sandy and brittle, with low shear strength.
2、 Reduce surface tension
The cohesion of tin-lead solder is even greater than that of water, making the solder appear as a sphere to minimize its surface area (under the same volume, the sphere has the smallest surface area compared with other geometric shapes to meet the requirements of the lowest energy state). The function of the flux is similar to that of the cleaner on the metal plate coated with grease. In addition, the surface tension is highly dependent on the cleanliness and temperature of the surface. Only when the adhesion energy is far greater than the surface energy (cohesion) can the ideal tin coating occur.
3、 PCBA board tin corner
When the eutectic temperature of solder is about 35 ℃ higher than that of solder, when a drop of solder is placed on a hot surface coated with flux, a meniscus is formed. To some extent, the ability of tin on the metal surface can be evaluated by the shape of the meniscus. If there is an obvious undercut on the meniscus of soldering tin, which is like water droplets on a greased metal plate, or even tends to be spherical, the metal is not weldable. Only the meniscus stretches into a smaller than 30. Only a small angle of can have good weldability.
In the process of PCBA welding of BGA, some bubbles will inevitably occur in the BGA solder ball, that is, the holes in the solder ball. In the industry, there are corresponding requirements for the acceptable standard of bubble size of tin balls.
How to improve PCBA welding? The introduction of PCBA processing factory to improve the PCBA welding method is expected to help you. At the same time, if you want to know more about PCBA processing information, you can pay attention to the update of ipcb.