PCBA Tech - Knowledge of reflow soldering equipment in SMT processing

Reflow soldering equipment is the most basic component of the SMT production line, also known as reflow soldering, which is a literal translation of English Re-flow Soldering. Reflow soldering is to remelt the solder pre-distributed on the printed board pads to realize the mechanical and electrical connection between the pins or solder ends of the chip components and the printed board in the SMT chip processing. Before reflow soldering, use a screen printer to print a proper amount of solder paste on the PCB pads, use a placement machine to paste the SMC/SMD components to the corresponding positions, and send the circuit boards with the components In the reflow soldering equipment, the solder paste is dried, preheated, melted, wetted, and cooled, and the components are soldered to the printed circuit board. Reflow soldering equipment has two basic structures, one is single temperature zone reflow soldering, and the other is multi-temperature zone reflow soldering.

The single temperature zone reflow soldering furnace controls the temperature of the temperature zone to change with time according to the reflow soldering temperature curve, and the PCB board is still in the furnace. The advantages of this single-temperature zone reflow soldering are small investment and easy temperature tracking of the set curve. The disadvantage is that the temperature periodically changes, resulting in a long production cycle and high energy consumption. It is generally suitable for single-piece or small-batch production. According to the editor of Zhongyan Electronics, many SMT chip processing manufacturers use this method for small batch SMT chip processing and production.

Multi-temperature zone reflow soldering is to divide the soldering furnace into several temperature zones with different temperatures according to the reflow soldering temperature curve, and the PCB board passes through each temperature zone at a constant speed to realize various processes such as preheating, reflow, and cooling.

Multi-temperature zone reflow soldering is characterized by relatively independent constant temperature control in each temperature zone, and the control algorithm is relatively simple. Its greatest advantage is high redemption efficiency, and it is suitable for continuous industrial mass production. However, the physical interval of each temperature range of multi-temperature reflow soldering makes each temperature range have a certain temperature difference, which will have certain thermal shock and thermal stress adverse effects on the PCB board. Therefore, more temperature zones can be used to reduce this Temperature difference.

Due to the "reflow" and "self-positioning" characteristics of reflow soldering, the requirements for the leading patch process are relaxed; good reflow soldering quality, solder saving, and good product consistency make reflow soldering equipment the mainstream equipment and key of the PCBA process equipment.

The above is about the relevant knowledge of reflow soldering equipment in SMT chip processing.