Reflow Soldering is the process of electrically and mechanically connecting electronic component with aPrinted Circuit Board (PCB).

The first step is to apply solder paste in a pattern on the PCB using a stencil printer.

Solder paste is a metal-alloy suspended in a mix of solvents, other materials and additives. The circuit board is then heated in a reflow-oven.

Reflow ovens are sealed boxes with an inside heater, fan and temperature sensor.

The circuit board will be placed in an oven, which gradually raises the temperature.

Solder paste melts when the temperature reaches its melting point. It fills in the gap between the component on the PCB.

The temperature will gradually drop, and then the solder paste will cool and solidify.

The Advantages of Reflow Soldering

Reflow soldering has become one of the most popular PCB soldering methods. Reflow soldering has many advantages:

• High quality welding, low false welding and empty welding rates;

• High-production efficiency suitable for PCBs with high volume;

• The process can be controlled easily and is simple.

• Low impact on the environment

The Types of Reflow Soldering

Reflow can be divided into two types: Single-sided and Double-sided.

Double-sided solder reflow is only possible with two reflow-ovens.

Consider the following factors when double-sided reflowing soldering:

• Temperature resistance of parts: Since the first side pieces will be going through the reflow twice, their temperature resistance should be able to handle the heat generated by two reflows.

• The smaller the part, the better. They are lighter and won't fall off in the second reflow.

• Layout of parts: The layout of the parts should be as uniform as possible in order to prevent too many pieces in one area leading to warping.

PCB Reflow Soldering is an important process in electronic manufacturing. Understanding the principles of reflow-soldering will improve PCB soldering efficiency and quality.