Materials SMT process include welding and patch materials such as solder, solder paste, adhesive, and process materials such as flux, cleaning agent,
and heat transfer medium. The main functions of assembly process materials are as follows:

(1) Solder and solder paste

Solder is an important structural material in the surface mount process. Different types of solder are used in different applications, which are used to
connect the metal surfaces of the objects to be soldered and form solder joints. Reflow soldering uses solder paste, which is the solder material and at
the same time pre-fixes the SMC/SMD with its viscosity. 

(2) Flux

Flux is an important process material in surface assembly. It is one of the key factors affecting the welding quality, and it is required in various welding
processes, and its main function is to flux. 

(3) Binder

Adhesives are bonding materials in surface assembly. When the wave soldering process is used, the components are generally pre-fixed on the PCB with
an adhesive. When the SMD is assembled on both sides of the PCB, even if reflow soldering is used, adhesive is often applied to the center of the PCB land
pattern to strengthen the fixation of the SMD and prevent the SMD from shifting and falling during the assembly operation. 

(4) Detergent

The detergent is used in surface assembly to clean the residue left on the SMA after the soldering process. Under the current technical conditions, cleaning
is still an indispensable and important part of the surface mount process, and solvent cleaning is the most effective cleaning method.