The assembly method and process flow of SMT mainly depend on the type of surface mount component (SMA), the type of components used and the condition of the assembly equipment. In general SMA can be divided into single and double mixed and mixed 3 types of surface mount 6 assembly. Different types of SMA assembly methods are different, the same type of SMA assembly can also be different.

  According to the specific requirements of assembly products and assembly equipment conditions to select the appropriate assembly, is the basis for efficient, low-cost assembly production, but also the main content of SMT process design.

Single side mixed assembly mode:

The single mixed assembly, namely SMC/SMD and THT element (17HC) distribution mixed in different side of PCB, but it is only one side welding surface. This kind of assembly methods are single side PCB and wave soldering (now generally use double wave soldering) process, there are two kinds of assembly.

1, first paste method: that is, in the PCB B surface (welding surface) first mount SMC/SMD, and then insert the A surface THC.

2, after the paste method: after the paste method is the first in the PCB A surface mount THC, after the B surface mount SMD.

   Double-sided hybrid assembly:

Double sided hybrid assembly that SMC/SMD and THC can be mixed in the same side of the PCB distribution, while SMC/SMD can also be distributed on the PCB side. Double side hybrid assembly using double-sided PCB, double wave soldering or reflow soldering. In this type of assembly method is also the first paste or paste the difference between the SMC/SMD, generally based on the type of SMC/SMD and the size of the PCB reasonable choice, usually the first paste more. The assembly of the two commonly used assembly methods:

1, SMC/SMD and FHC in the same way: SMC/SMD and THC on the side of PCB.

2, SMC/SMD and iFHC in different ways: the surface mount integrated chip (SMIC) and THC on the PCB side of the A, and the SMC and small outline transistor (SOT) on the B surface.

This type of assembly is due to a single or double sided SMC/SMD in the PCB, and the difficult to assemble the surface of the lead into the assembly of components, so the assembly density is quite high.

    The whole surface assembly:

Full surface assembly means that only SMC/SMD on PCB without THC. Due to the current components have not yet fully realized SMT, the practical application of this assembly is not much. This type of assembly is usually performed on thin wire PCB or ceramic substrates by means of fine pitch devices and reflow soldering processes. It also has two assembly methods:

1, single surface assembly: the use of single sided PCB assembly in SMC/SMD.

2, double-sided surface assembly: the use of double-sided PCB on both sides of the assembly, SMC/SMD, a higher density of assembly.