Reflow soldering is a technology for soldering surface mount components onto a printed circuit board (PCB), which is widely used in the electronics manufacturing industry. The following is an introduction to it:

Principle

External heat sources are utilized to make the solder paste melt when heated, connecting the pins or electrodes of the electronic components with the pads on the PCB, thus forming a reliable electrical and mechanical connection.

Equipment

Reflow soldering equipment usually consists of a heating system, a conveying system, a cooling system, and a control system, etc. The heating system generally adopts infrared heating, hot air heating, or a combination of both, enabling the PCB to go through stages such as preheating, temperature rising, reflow, and cooling in different temperature zones.

Process Flow

• Solder Paste Printing: An appropriate amount of solder paste is printed onto the pads of the PCB through a stencil.

• Component Mounting: A pick-and-place machine is used to accurately place the surface mount components at the corresponding positions on the PCB.

• Reflow Soldering: The PCB with the mounted components is placed into the reflow soldering furnace and heated according to the set temperature curve. In the preheating zone, the PCB and components are slowly heated to remove moisture and solvents, and at the same time, the flux in the solder paste is activated; in the temperature rising zone, the temperature rises rapidly to make the solder paste reach the melting temperature; in the reflow zone, the solder paste melts completely, wets the pins of the components and the pads of the PCB, and forms good solder joints; in the cooling zone, the solder joints are rapidly cooled and solidified to complete the soldering process.

Advantages

• High soldering quality, capable of achieving high-precision soldering, with full and reliable solder joints and good consistency.

• High production efficiency, suitable for large-scale automated production and enabling continuous operation.

• Less pollution to the environment. Compared with traditional soldering processes such as wave soldering, fewer chemical substances such as flux are used.

Application Fields

It is widely applied in the manufacturing of various electronic devices, such as the PCB assembly in the fields of computers, mobile phones, tablets, automotive electronics, aerospace electronics, etc