The main differences between wave soldering and reflow soldering are as follows:
1. Welding principle
–Wave soldering: It is a process in which melted solder is used to form a wave peak through an electric or electromagnetic pump, causing the pins of electronic components inserted on a printed circuit board (PCB) to come into contact with the PCB pads, thereby achieving soldering. Simply put, it is to solder the pins through solder peaks.
–Reflow soldering: It uses heating to melt the solder paste pre printed on the PCB pads, thereby achieving electrical connection between surface mount components (SMC/SMD) and PCB pads. Welding components by melting and solidifying solder paste.
2. Applicable component types
-Wave soldering: mainly used for soldering plug-in components (THT), such as pin resistors, capacitors, diodes, transistors, etc. These components have pins that pass through holes on the PCB board for soldering.
–Reflow soldering: mainly used for soldering surface mount components (SMC/SMD), such as surface mount resistors, surface mount capacitors, chips, etc. These components are directly attached to the surface of the PCB board for soldering.
3. Temperature curve during welding process
-Wave soldering: The temperature curve is relatively simple, mainly including preheating, soldering (wave), and cooling stages. The preheating temperature is generally around 90-100 ℃, and the welding temperature depends on the solder material, usually around 250 ℃, followed by rapid cooling.
-Reflow soldering: The temperature curve is relatively complex, including preheating zone, constant temperature zone, reflow zone, and cooling zone. The temperature in the preheating zone gradually increases, the constant temperature zone evaporates the solvent in the solder paste, the reflux zone reaches the melting point of the solder paste, causing it to melt and flow again, and the cooling zone solidifies the solder joint. The temperature change throughout the entire process requires precise control.
4. Characteristics of welding quality
-Wave soldering: It has good soldering stability for plug-in components, but it is prone to bridging (short circuit), virtual soldering, and other problems, especially when the pin spacing is small. And because wave soldering involves soldering the entire PCB board, it may cause thermal shock to some components that are not resistant to high temperatures.
-Reflow soldering: It has high soldering accuracy for surface mount components, can achieve very small component spacing soldering, good solder joint quality, and high consistency. However, if the printing quality of solder paste is poor or the temperature control is not good, defects such as open circuits and virtual soldering are also prone to occur.
5. Equipment and Costs
-Wave soldering: The equipment structure is relatively simple, mainly composed of a flux coating device, a preheater, a tin furnace, and a conveyor device, with low equipment costs. However, due to the need for a large amount of solder, the operating costs (solder consumption, energy consumption, etc.) are relatively high.
-Reflow soldering: The equipment is relatively complex, including multiple parts such as printing machines, surface mount machines, reflow soldering furnaces, etc. Especially for reflow soldering furnaces, precise temperature curve control is required, resulting in high equipment costs. However, the amount of solder paste used is relatively small, and the operating cost is lower in terms of solder.
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