TQFP

Advantages and disadvantages and countermeasures

More than 90% of integrated circuits in the world use plastic packaging. The advantages of plastic packaging instead of air-tight packaging are its low cost, high assembly density, light weight, good operability, and high work efficiency.

However, the poor waterproof performance of polymer materials such as epoxy resin in the molding compound has always been one of the main reasons affecting the reliability of the device. After water vapor enters the inside of the package, it is easy to condense at the interface of different materials. The combination of condensed water vapor with ions and impurities can lead to corrosion and short circuits. In the reflow soldering process of the surface mount process, due to thermal expansion, it will cause delamination and cracking of the package, which eventually leads to device failure. With the development of high-density and miniaturization of electronic devices, the influence of water vapor on plastic-encapsulated devices is increasing, which has gradually aroused interest in research at home and abroad.

Water vapor content is the main cause of delamination cracking of the device; the bonding surface between the silver paste and the molding compound, the chip pad and the molding compound is the weak link delamination phenomenon of the TQFP device is generated and expanded by these parts. The PECVD SiNx film can effectively reduce the moisture content entering the TQFP device and eliminate cracking and delamination to a certain extent. The thicker the film, the better the waterproof effect and the more obvious the effect of eliminating cracking and delamination.