The working principle of the reflow soldering process in the PCB sample patch

inPCB model patchIn the processing process, the reflow soldering process is very important, it will directly affect the forming of the chip circuit board. After the sample patch is completed, it needs to be inspected. After checking that there is no error, reverse or mis-attachment, the circuit board can be placed on the reflow oven conveyor belt to implement the reflow soldering process. For the reflow soldering process, the key is the temperature control. The reflow soldering process of PCB template patch includes four steps of preheating, heat preservation, reflow and cooling. Here is a brief introduction to its working principle.

The reflow soldering process of the PCB template patch: first preheating, in fact, refers to heating the PCB to increase its temperature from room temperature to 150 ℃ ~ 170 ℃, so as to quickly enter the insulation section. The main purpose of heat preservation is to keep the components at a relatively stable temperature so as to reduce the temperature difference between the components and balance the temperature of the circuit board. The temperature in the heat preservation zone is generally controlled at about 180°C. When the PCB template patch is heated in the reflow zone, the temperature of the heater should not exceed 245℃, so that the temperature of each component can rise quickly and reach the peak value. After the heating is completed, the PCB board is transported out of the furnace using a conveyor belt and placed in a room temperature environment for natural cooling. During the heating process of the PCB sample board, the lead-tin powder contained in the solder paste has been melted and fully moistened. At this time, the solder paste can be connected to the surface of the PCB board. After natural cooling, the PCB board will appear bright and bright. Good-shaped solder joints.

During reflow soldering of PCB prototypes, the soldering quality is greatly affected by the environmental humidity. If the environmental humidity is higher than 75%, white corrosive substances are more likely to appear on the pins and metals of the components. Therefore, in the actual operation During the process, attention should be paid to controlling the environmental humidity at 40% to 60% to ensure the soldering quality of the reflow soldering process of the PCB sample board.