prevent the occurrence of solder balls
To prevent the occurrence of solder balls, we checked the package size and pad design during the DFM review, mainly considering reducing the amount of tin on the bottom of the component, thereby reducing the chance of solder paste squeezing out the pad. Optimized for different package components The hole methods and sizes are different, and should be optimized according to the actual component specifications and specific process parameters.
In summary, it is a fast and efficient solution to optimize the problem of solder balls by optimizing the opening size of the steel mesh. Of course, the reasons for the production of solder balls are also various, and the solutions are also different, such as optimized temperature curve of the reflow furnace, machine paste Packing pressure, workshop environment and temperature mixing before solder paste printing are also important ways to solve the problem of tin beads. The experienced engineers of company E share with you a few points:
1) Optimize the temperature curve setting of the reflow furnace, the temperature rising slope can not be too fast in the preheating stage, the temperature rising slope setting
Less than 2℃/second, especially the components on the complex server motherboard are too dense, to ensure that the components warm up evenly and smoothly.
2) Control the mounting pressure when the LED packaged components are mounted by the machine.
3) Before printing, the solder paste shall be in strict accordance with the specifications for more than 4 hours of warm-up time, and be stirred for 3-5 minutes when used
In the production process, the process engineer can summarize the shape and opening of the steel mesh when dealing with and solving various problems
For the size, it is necessary to perform point-to-point analysis and optimization according to the bad phenomenon of solder joints, and to continuously sum up experience based on actual problems to optimize the amount of tin. It is very important to regulate the opening design of the steel mesh, otherwise it will directly affect the production pass rate.
This is exactly:
Tin beads have a bad influence,
Short-circuit failure is mostly due to it.
Careful consideration of various programs,
The steel mesh optimizer is the best.