SMT Patch Welding Processing Methods And Requirements

The SMT patch welding process is an indispensable and important link in the entire circuit board manufacturing process. If there are errors in the SMT patch welding process, it will directly affect the welding quality of the circuit board. Therefore, it is necessary to understand the process flow of SMT chip welding processing.

1. SMT patch welding processing method

① SMT patch welding processing-hot air reflow soldering

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 a nozzle and comes into contact with the pads and component surfaces. The advantage of hot air reflow soldering is that it can heat the entire welding area evenly, thereby reducing thermal stress and improving welding quality. Hot air reflow soldering is currently the most common method in SMT patch soldering processing.

② SMT patch welding processing-infrared reflow soldering

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 advantages of this method are high thermal efficiency and fast heating speed. However, infrared heating can easily lead to local overheating, so the energy and heating time of infrared radiation need to be controlled.

③ SMT patch welding processing-vapor phase reflow soldering

Vapor phase reflow soldering is a method that uses steam for heating. In this method, the heat exchange fluid is heated to boiling in the heating zone, forming a vapor layer. Electronic components and pads are heated through 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. However, 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 in 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 high, and special nitrogen reflow soldering equipment is required.

⑤ SMT patch welding processing – full heat reflow soldering

Full thermal 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 and 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 patch welding processing-laser reflow welding

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

2. SMT patch welding processing requirements

① Solder joint height: that is, the height of the solder crawling onto the pins, single-sided board is not less than 1mm; double-sided board is not less than 0.5mm, and the tin must be penetrated.

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

③ Solder joint surface: smooth and bright, without black spots and other debris, and without defects such as spikes, pits, pores, etc.

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 and is suitable for different electronic components and soldering requirements. These methods are often combined with actual product characteristics to achieve the best results during the actual SMT patch welding process, and they also need to be selected based on processing conditions, component types, and design requirements.

Leave a Comment

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

Scroll to Top