Solder paste for reflow12/17/2023 The short circuit is an intolerable problem for electronic product manufacturers. When tin whiskers form, they usually grow along the path between two conductors, resulting in short circuits and false signals between the paths. The occurrence of tin whiskers will increase the potential short circuit between components and leads. In addition, many people believe that corrosive environments such as high temperatures and humidity will also affect the growth of tin whiskers. Thus, the compressive stress on the grain is increased. With the increase of aging time, the IMC thickness increases, and the IMC grain coarsens. For SAC solder paste, Cu6Sn5 IMC will be generated first. High-temperature aging will accelerate the growth of IMCs in solder joints. However, since the SnAg0.3Cu0.7 solder paste has more Sn content, it is easier to form a large number of tin whiskers. For example, the Sn contents of SnAg3Cu0.5 and SnAg0.3Cu0.7 solder pastes are both higher than 95wt%, which makes them easy to generate tin whisker growth. There are many factors affecting the growth rate of tin whiskers. Eventually, the whiskers are extruded from the tin layer after stress release. There are many reasons for the occurrence of mechanical stress, including PCB surface electroplating and the formation of intermetallic compounds (IMCs) by Sn-Cu diffusion. The driving force of whisker growth on the tin surface can be attributed to the mechanical stress on the tin grain. The length of tin whiskers is quite small, which is commonly between 20-100μm, while it is not excluded that the length can reach the millimeter level in some cases. If the Sn layer is plated on the bonding pad, tin whisker growth may occur. PCB surface finishes are normally completed through electroplating. The tin whisker issue is a spontaneous surface defect on pure tin or objects with high tin content, such as solder joints or PCB surface finishes. For lead-free solder paste with low silver content (such as SnAg0.3Cu0.7), higher tin content may bring hidden dangers to packaging reliability, such as tin whisker growth.ġ. However, tin does not always create benefits. Due to the excellent bonding effect of tin and copper under heating, tin-based solder paste is mainly used in the field of soft soldering at present. In the packaging of electronic products, solder paste, and other soldering materials are mostly used to bond the chip and substrate to realize the electrical path. Tin Whisker Issue for SnAgCu Solder Paste_Shenzhen FitechĮlectronic products often contain various types of chips, which need to form electrical circuits in the form of packaging.
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