For mixed technology assembly parts, generally λ The wavefront also uses turbulence waves. This type of wave is relatively narrow and carries a high vertical pressure during disturbance, which allows solder to penetrate well between tightly placed pins and surface mounted component (SMD) pads, and then use λ Wave completes the formation of solder joints. Before making any evaluations of future equipment and suppliers, it is necessary to determine all technical specifications of the boards welded using wave crests, as these can determine the performance of the required machines.

(1) According to statistics, the introduction of SPI can effectively reduce the unqualified rate of the original finished PCB by more than 85%; The cost of repair and scrapping has been significantly reduced by over 90%, and the quality of factory products has significantly improved.

(2) The combination of SPI and AOI, through real-time feedback and optimization of the SMT production line, can make production quality more stable, significantly shorten the unstable trial production stage that must be experienced when introducing new products, and correspondingly save costs.

(3) It can significantly reduce the misjudgment rate of AOI regarding soldering, thereby improving the pass through rate and effectively saving manpower and time costs for human error correction. According to statistics, 74% of the unqualified parts in the current finished PCB are directly related to soldering, and 13% are indirectly related. SPI effectively compensates for the shortcomings of traditional detection methods through 3D detection.

(4) Some components on PCBs, such as BGA, CSP, PLCC chips, etc., cannot be detected by AOI after chip reflow due to the light blocking caused by their own characteristics. SPI minimizes the adverse conditions of these devices behind the furnace through process control.

(5) With the increasing precision of electronic products and the trend of lead-free soldering, SMT components are becoming increasingly miniaturized. Therefore, the quality of solder paste printing is becoming increasingly important. SPI can effectively ensure good solder paste printing quality and significantly reduce the possibility of defective products.

(6) As a means of product quality process control, quality hazards can be detected in a timely manner before reflow soldering, so there is almost no possibility of repair costs or scrapping, effectively saving costs.

The light is obstructed, and AOI cannot detect the reflow of the patch. SPI minimizes the adverse conditions of these devices behind the furnace through process control.

There are forced hot air convection, electric heating plate convection, electric heating rod heating, and infrared heating. Among these methods, forced thermal convection is usually considered the most effective heat transfer method for wave soldering machines in most processes. After preheating, the circuit board uses a single wave（ λ Wave or double wave (disturbance wave and λ Welding is carried out using the wave method. For perforated components, a single wave is sufficient. When the circuit board enters the wave ridge, the direction of solder flow is opposite to the direction of the board's travel, which can generate eddy currents around the component pins. This is like a washing process, which removes all residual flux and oxide film from the solder joint and forms wetting when the solder joint reaches the wetting temperature.