As a key material in electronic packaging and welding, solder balls will undergo a series of changes in performance after long-term use, which may affect the reliability and stability of electronic equipment.
The mechanical properties of solder balls will change significantly during long-term use. Initially, solder balls have good elasticity and toughness, can provide reliable connections between electronic components and substrates, and withstand certain mechanical stress and vibration. However, over time, solder balls will gradually creep. Creep is like the gradual deformation of plasticine under long-term stress. Under continuous external force, the shape of solder balls will gradually change, resulting in uneven stress distribution at the connection. This change in stress distribution may reduce the connection strength between solder balls and components or substrates, making them prone to loosening or even falling off. Moreover, long-term use may also increase the hardness of solder balls, making them more brittle and more likely to break when impacted by external forces, thereby destroying the electrical connection between electronic components.
Electrical performance is one of the important indicators of solder balls, and its electrical performance will also be affected after long-term use. The main function of the solder ball is to conduct current, but during long-term use, the microstructure inside the solder ball may change, resulting in increased resistance. This is like a road that was originally unobstructed, but due to potholes and obstacles on the road surface, the resistance of vehicles to travel increases. The increased resistance will cause the solder ball to generate more heat when conducting current, further accelerating the aging of the solder ball. At the same time, the contact resistance between the solder ball and the component or substrate may also increase, affecting the transmission quality of the signal, causing problems such as signal distortion and increased noise in electronic equipment, and even affecting the normal operation of the equipment in severe cases.
The environment in which the solder ball is located often contains various chemicals, such as oxygen, moisture, acidic or alkaline gases, etc. During long-term use, the solder ball will react chemically with these chemicals. Solder balls are usually made of metals such as tin and lead, which are easily oxidized by oxygen to form an oxide film on the surface of the solder ball. The oxide film is like a heat-insulating layer, which will hinder the good contact between the solder ball and the component or substrate, affecting the welding quality and electrical performance. Moreover, if there are acidic or alkaline gases in the environment, the solder ball may also undergo corrosion reactions, resulting in a reduction in the volume of the solder ball and structural damage, further reducing its connection strength and reliability.
The solder ball is affected by temperature changes in electronic devices. During long-term use, the solder ball will experience multiple thermal cycles, that is, temperature increases and decreases. This thermal cycle will cause thermal stress in the solder ball, just like repeatedly bending a wire will eventually break it, and the solder ball may crack after multiple thermal cycles. The generation of cracks will destroy the integrity of the solder ball, reduce its thermal conductivity, and prevent the heat generated by the electronic device during operation from being dissipated in time, causing the device temperature to rise, affecting the performance and life of the device. Moreover, thermal cycles may also make the mismatch of thermal expansion coefficients between the solder ball and the component or substrate more prominent, further exacerbating the stress at the connection site and increasing the risk of solder ball failure.
Through microscopic observation, it can be found that the microstructure of the solder ball will change significantly after long-term use. The originally uniform and dense microstructure will become loose, with holes and grain boundary defects. These microstructural changes will affect the physical and chemical properties of the solder ball, causing its strength, toughness, and conductivity to decline. Just like a building, if there are holes and cracks in the internal structure, its load-bearing capacity will be greatly reduced, and the microstructural changes of the solder ball will also make it perform poorly when it comes to bearing external forces and conducting current.
In order to reduce the impact of the performance changes of the solder ball after long-term use, in the design and manufacturing process of electronic equipment, it is necessary to select solder ball materials with reliable quality, optimize the welding process, and take effective protective measures, such as sealing the electronic equipment to reduce the contact between the solder ball and the external environment, thereby extending the service life of the solder ball and ensuring the reliability and stability of the electronic equipment.
