The difference between reflow soldering and wave soldering

What is reflow soldering? Reflow soldering refers to the process of melting the solder paste pre-coated on the pad by heating to achieve electrical interconnection between the pins or solder ends of the electronic components pre-mounted on the pad and the pads on the PCB, so as to achieve the purpose of soldering the electronic components on the PCB. Reflow soldering relies on the effect of hot air flow on the solder joints. The gel-like flux undergoes a physical reaction under a certain high-temperature air flow to achieve SMD soldering; so it is called "reflow soldering" because the gas circulates in the welding machine to generate high temperature to achieve soldering. Reflow soldering is generally divided into preheating zone, heating zone and cooling zone.

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Reflow-soldering Machine

What is wave soldering? The molten solder (lead-tin alloy) is sprayed into a solder wave as required by the design through an electric pump or electromagnetic pump, so that the printed circuit board pre-installed with components passes through the solder wave to achieve the mechanical and electrical connection between the component solder end or pin and the printed circuit board pad. The wave soldering machine is mainly composed of a conveyor belt, a flux adding area, a preheating area and a wave soldering furnace. Its main material is solder bar.

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Wave-soldering Machine

The difference between the two：

Working principle:

1. Wave soldering is to solder components by forming a solder wave through molten solder.

2. Reflow soldering is to melt the solder paste through high-temperature hot air to form a firm connection between the components and the PCB pads.

Scope of application:

1. Wave soldering is suitable for THT electronic components.

2. Reflow soldering is mainly used for surface mount technology (SMT), which is suitable for soldering various patch components, such as resistors, capacitors, IC chips, etc.

Process flow:

1. Wave soldering requires spraying flux first, and then preheating, soldering and cooling.

2. Reflow soldering is to apply solder paste on the PCB, and then heat and melt the solder paste for soldering.

The process sequence is reflow soldering followed by wave soldering. Generally, SMD components are much smaller than plug-in components, and circuit boards are assembled in order from small to large.