140mm LED Aluminum Pin Fin COB Heat Sink

Defects and Measures for Vacuum Brazing of Aluminum Plate Fin Heat Exchangers

Aluminum plate fin heat exchanger is one of the widely used high-efficiency heat exchange equipment, with advantages such as simple structure, high heat exchange efficiency, and small volume. During the manufacturing process, the use of vacuum brazing technology can greatly improve the quality and stability of products. However,

During the brazing process, it is inevitable to encounter some defects, such as bubbles, leaks, etc., which can reduce the reliability and service life of the product.

1. Bubbles

Bubble is one of the most common defects in the brazing process, which refers to the formation of air adsorbed by the brazing material in the liquid state due to impurities such as oxide skin and grease on the surface of the brazing joint before the brazing material is heated and melted. The presence of bubbles can lead to a decrease in welding strength and also reduce the heat transfer efficiency of the heat exchanger.

2. Leakage

Leakage refers to defects that may occur during the brazing process when the brazing seam is not fully filled or the surface of the aluminum material is partially damaged. It can lead to leakage of the working medium, and in severe cases, even equipment damage.

3. Residual stress during welding process

The heat generated during the welding process can cause local deformation and shrinkage of the material, resulting in residual stress during the welding process. If the residual stress is not released in a timely manner, it can lead to deformation of the plate fin heat exchanger, and even lead to weld seam fracture in severe cases.

1. Improper surface treatment of brazing parts

The presence of impurities such as grease and oxide skin on the surface of the brazing joint can cause the brazing material to adsorb air and generate bubbles when in liquid state, or the brazing material cannot completely fill the brazing joint and produce leakage defects.

2. Improper welding process

Improper control of parameters such as welding temperature, welding pressure, and welding time can also lead to the occurrence of brazing defects. For example, low welding temperature or insufficient welding pressure can lead to insufficient wetting of the brazing surface by the brazing material, resulting in leakage defects. Excessive welding temperature can increase residual stress and cause deformation of the plate fin heat exchanger.

3. Poor material quality

Factors such as uneven material composition, insufficient strength, and insufficient hardness can also affect the effectiveness of brazing. For example, if the quality of the sheet metal is poor, it is easy to produce defects, which are difficult to compensate for through brazing technology. During the surface treatment process of brazed joints, attention should be paid to cleanliness and surface smoothness to avoid brazing defects caused by impurities such as grease and oxide skin. Cleaning agents and pickling agents should be used to clean the surface of brazed joints, removing impurities and oxide scales.

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