The traditional production methods of solder ball particles include gas atomization method, centrifugal atomization method and shredded remelting method.

1. Gas atomization method

The gas atomization method uses the pressure of the gas to impact and break the liquid flowing through the nozzle. In the production of metal particles by gas atomization, due to the influence of some process parameters such as the pressure of the atomized gas on the dispersion and size of the atomized particles, and the influence of the properties of the atomized gas medium on the distribution and shape of the atomized particles Therefore, in the process of producing tin particles by gas atomization method, the dispersion of tin particles is wide, and it is necessary to pass multiple screenings and tests to obtain particles that can meet the requirements of use.

4. Centrifugal atomization method

Centrifugal atomization is a method of processing metal powder in which the molten metal liquid to be atomized flows onto the rotating disk, and under the action of centrifugal force, it breaks away from the edge of the rotating disk and falls into the cooling medium to solidify. The degree of centrifugal atomization mainly depends on the peripheral line speed, the feeding speed of liquid metal, the performance of liquid metal and the structure of the turntable. Although the production efficiency of centrifugal atomization is high, the particle distribution produced is relatively dispersed and the roundness It is not high, and the particles that meet the requirements of use must be screened and inspected many times.

3. Shredded remelting method

The process of manufacturing BGA solder balls by shredding and remelting is to first make the solder into filaments of a certain specification, then cut them into uniform segments with a shearing machine, and immerse the segments in hot oil at an appropriate temperature to make them Melted and solidified into spherical particles, after screening, cleaning and inspection, BGA solder balls that meet the requirements are obtained. The principle of producing metal particles by wire cutting and remelting is simple, but it requires high precision of manufacturing machinery: because the wire drawing process is easy to cause the thickness of the solder wire to be uneven, which will further affect the size of the produced particles. During the melting process, the temperature and type of the liquid medium, the control of the remelting time and the control of the process will all affect the roundness, surface quality and crystal structure of the produced solder balls, thus affecting the quality of the product in the BGA package. make an impact. According to production practice, the wire-cut remelting method must be screened to obtain solder balls that meet the requirements, which greatly affects the production efficiency and benefits of this method.

4. Uniform droplet forming method

When a certain liquid flows out from the jet nozzle at a certain speed (smooth flow), if a certain frequency of longitudinal disturbance is applied to the liquid inside the jet tube, the internal pressure of the liquid will be distributed according to the waveform. When such a liquid is ejected from the nozzle , the pressure change will cause a corresponding change in the diameter of the jet. The surface tension of the liquid at the larger diameter is small, and the surface tension of the liquid at the smaller diameter is large. At this time, the liquid at the high pressure moves closer to the low pressure, so that the diameter of the jet is further reduced, forming a sausage-shaped jet fracture mode, resulting in a uniform liquid droplet production.