Design and verification of a new electromagnetic shielding material suitable for QFP packaging

Abstract

With the development of information and digital electronic instruments, the requirements for precision and sensitivity are becoming higher and higher, and the requirements for anti-electromagnetic interference are also increasing. Electromagnetic radiation not only interferes with the use of electronic components and various precision instruments, but also leads to information leakage. How to improve the anti-emi capability of chip becomes an important research topic in chip packaging field. Electromagnetic shielding material is to use the reflection and absorption of materials to achieve the purpose of shielding, which is an effective method to effectively suppress electromagnetic interference and improve the stable work of chips in complex electromagnetic environment. In this paper, by means of electroless plating, the hollow structure shielded filling particles are coated with silver, iron and nickel metal layers of different thickness. The coating with different thickness gradient is formed through the control process, and the filling proportion of shielded particles is optimized to achieve low threshold and high shielding efficiency. When the electromagnetic field passes through this layered electromagnetic shielding structure, it achieves good magnetic shielding effect through the reflection, absorption and reflection of conductive layer-magnetic layer-conductive layer. After testing, its electromagnetic shielding efficiency reaches 74dB in the range of 9kHz-1.5GHz. The electromagnetic shielding film was prepared on the surface of epoxy resin plastic packaging base through optimization test, and the shielding effect, reliability and bonding force of the shielding coating reached the requirements of QFP packaging process.