Printed Circuit Board Assembly Design
PCB design should begin with determining the layouts of the SMT (surface mount technology) and DIP (dual in-line package) on the both sides of PCB. Different ways of assembly lead to different processing which cause different requirements for production lines.
In the actual designing process, to guarantee a higher straight-through rate of PCB soldering, the preferably assemble ways that we always use are listed as follows.
1. To avoid one more step in the assembly process, it is better not to use wave soldering method to solder just a few SMDs on the B side of panel.
2. Simple SMD refers to the R, L and C devices of package 0603, 0805 and 1206, and devices of package SOT-23.
3. When soldering the second side, the components solder joints on the first side will melt again, and they will attach to the bottom of PCB just by the surface tension, and those heavy ones are tend to fall off. Thus, keep heavy components mounted on A side while light ones on B side.
Assembly type 1: single mix
It has SMD as well as THC(plug-in) on one side. Therefore, you need to use reflow soldering method to solder SMD firstly, and then manually soldering THC.
Assembly type 2: top mix bottom with SMD
The BOT (solder paste) is first welded by reflow, then the panel is turned over and the TOP (solder paste) is added by reflow soldering. Finally, the panel is re-turned again, and the carrier is added to the BOT for wave soldering.
Assembly type 3: single side with THC
Use wave soldering method to mount all THC on one side.
Assembly type 4: single side with SMD
Use reflow soldering method to mount all SMD on one side.
Assembly type 5: SMD on both sides
Use reflow soldering method to mount all SMD on both sides.