SMT soldering processing methods and requirements

SMT soldering processing methods and requirements

Abstract: The smt patch welding process is an essential and important link in the entire circuit board manufacturing process. If there is a mistake in the smt patch welding process, it will directly affect the welding quality of the circuit board. Therefore, it is extremely necessary to understand the process flow of smt patch welding processing. Next, SZTech-SMT will share with you the smt patch welding processing methods and requirements, hoping to bring you some help!

1. SMT patch welding processing method

① SMT patch welding processing – hot air reflow welding

Hot air reflow soldering is a method that uses hot air convection to heat electronic components and pads. In this method, hot air is blown from the heated zone of the reflow oven through nozzles to make contact with the places and component surfaces. The advantage of hot air reflow soldering is that it can evenly heat the entire soldering area, thereby reducing thermal stress and improving soldering quality. Hot air reflow soldering is the most common in SMT patch soldering processing.

② SMT patch welding processing – infrared reflow welding

Infrared reflow soldering is another common reflow soldering method. It uses infrared light to heat electronic components and pads. Infrared rays have strong penetrating power and can penetrate deep into the material for heating. The advantage of this method is high thermal efficiency and fast heating speed. However, infrared heating can easily lead to local overheating, so it is necessary to control the energy and heating time of infrared radiation.

③ smt chip welding processing – vapor phase reflow welding

Vapor phase reflow soldering is a method that utilizes steam for heating. In this method, the heat exchange fluid is heated to boiling in a heating zone, forming a layer of vapor. Electronic components and pads are heated by a layer of vapor. This heating method has the characteristics of high heat transfer efficiency and uniform heat distribution, which can reduce thermal stress and improve welding quality. But this method requires more complex equipment and higher operating skills.

④ SMT patch welding processing – nitrogen reflow welding

Nitrogen reflow soldering is a reflow soldering method performed under a nitrogen atmosphere. Nitrogen can effectively reduce oxidation and improve welding quality. In addition, nitrogen reflow soldering can also improve the wettability of solder, thereby reducing solder joint defects. However, the disadvantage of this method is that the cost of nitrogen is relatively high, and special nitrogen reflow soldering equipment is required.

⑤ SMT patch welding processing – full heat reflow welding

Full heat reflow soldering is a reflow soldering method that combines multiple heating methods such as hot air, infrared rays, and steam. This method can make full use of the advantages of various heating methods to improve welding quality and efficiency. Full heat reflow soldering requires more complex equipment and higher operating skills, but for some products with special requirements, full heat reflow soldering can bring better soldering results.

⑥ SMT soldering processing – laser reflow welding

Laser reflow soldering is a method that uses a laser to heat electronic components and pads. The laser has a high energy density and can rapidly heat the welding area in a short time. This method has the advantages of fast heating speed and precise positioning and is especially suitable for welding high-density and miniaturized electronic components. However, the cost of laser reflow soldering equipment is relatively high and requires high operating skills.

Smt soldering processing requirements

① Solder joint height: that is, the height of the solder attached to the pins, is not less than 1mm for single-sided boards; not less than 0.5mm for double-sided boards, and tin penetration is required.

② Solder joint shape: conical and covering the entire pad.

③Solder joint surface: smooth, bright, free of sundries such as black spots, and free of defects such as spikes, pits, and pores.

④ Solder joint strength: no false welding or false welding.

⑤ Solder joint cross-section: There is no tin cracking on the contact surface between the pin and the solder.


There are many types of smt patch welding processing methods. Each of these types has unique advantages and disadvantages for different electronic components and soldering requirements. These methods are often combined with actual product characteristics to achieve the best results in the actual smt patch welding process, and they also need to be selected according to processing conditions, component types, and design requirements. The above content is provided by SZTech-SMT for you. To learn more about smt welding processing, please visit

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top