Because the "
double-sided reflow process" requires two reflows, there will be some process restrictions. The most common problem is that when the board goes to the second reflow furnace, the parts on the first side will be affected by Falling due to gravity, especially when the board flows to the reflow zone of the furnace at high temperatures, this article will explain the precautions for the placement of parts in the double-sided reflow process:
Generally speaking, smaller parts are recommended to be placed on the first side to pass through the reflow oven, because the deformation of the PCB will be smaller when the first side passes through the reflow oven, and the precision of solder paste printing will be higher, so it is more suitable. Put smaller parts.
Secondly, the smaller parts will not fall off the second time through the reflow furnace. Because the parts on the first side are placed directly on the bottom side of the circuit board when hitting the second side, when the board enters the reflow area, it will not fall off the board due to excessive weight.
Third, the parts on the first panel must go through the reflow oven twice, so its temperature resistance must be able to withstand the temperature of two reflows. The general resistance and capacitor are usually required to pass the high temperature of at least three reflows. This is for It meets the requirements that some boards may need to go through the reflow furnace again due to maintenance.
