Solder paste has evolved into a highly refined surface mount material that has played an important role in the assembly of fine-pitch SMT devices, high-density assembly and other assembly techniques. With the continuous improvement of circuit assembly density and reflow soldering technology widely used, and the concept of "green assembly" put forward, SMT chip solder paste also constantly put forward new requirements. Currently, research and development of solder paste is still in progress, the main research focuses on the following two aspects.

1. Compatible with the development of device and assembly technology

(1) Fine pitch technology

Multi-lead, thin-pitch, SMIC devices using FPTs are widely used. The assembly of these devices places high demands on assembly processes and solder paste characteristics. In order to ensure the fine pitch device mounting reliability, solder paste is required throughout the process to maintain good performance at design time. Therefore require the solder particles smaller.

(2) Compatible with the development of new devices and assembly technologies

BGA chip, CSP chip and other new device assembly, as well as the bare chip assembly, hybrid assembly of bare chips and devices, high-density assembly, three-dimensional assembly and other new forms of assembly, have different requirements for solder paste, and the corresponding research Work has never stopped before.

2 and environmental requirements and green assembly requirements to adapt

(1) Development of water-soluble solder paste compatible with water cleaning. Solder pastes containing water-soluble fluxes have been put to practical use in the light of the restrictions on the use of HCFCs, but the work on the correlation studies continues.

(2) disposable solder paste application. The most thorough way to avoid the use of HCFCs is to use post-weld disposable flux and welding processes. Often used two kinds of post-welding disposable technology, one is the use of low solid content post-processing disposable flux, Shanghai SMT chip processing, such as polymers and synthetic resin flux, this flux can be used directly in the wave soldering process or preparation Solder paste is used in reflow soldering processes; the other is dual wave soldering equipment and IR reflow soldering equipment that are used in inert gases or in reaction atmospheres, such as nitrogen protection.