A Study On High-temperature Resistant Metallization For Ferrite And Its Key Issues In Industrialization

With the rapid growth of information and communication industry, electronic components as its carrier exhibit high-speed, integrated, green trends. The study on the reliability of electronic components and electric interconnect technology has become an internationally popular field of study. Inductors are considered difficulty to be integrated, and its metallization still relies on electroplating method, which is low-efficient, high-cost and unavailable for the420℃high-temperature assembly process of winded inductors. In this paper, we investigated the metallization technology for ferrite from theory to practice. Finally, this technology has been applied to the industry process and it is the first implementation of this kind.The main efforts are listed as follows:1. We proposed a design of multi-layer composite thin film suitable for high-temperature(420℃) process. Experimental samples were prepared by magnetron sputtering deposition method. Complete industry standard test was done, and to select the optimum sputtering parameters, we studied the performance of the samples in various sputtering parameters. The thin film dissolution process is covered, including the morphology and composition of the intermetallic compound generated by the surface reaction and the impact of these products on the dissolution rate. Rising of temperature can change the reaction products, speed up the dissolution. Based on the analysis, we choose Ni-V as the barrier material. The test results proved that the composite film is valid to meet the adhesive and high-temperature resistance requirements and is suitable for large-scale production. The paper on surface reaction between SnAgCu solder and metal film at420℃high temperature was published and indexed by SCI and El.2. We studied the film growth theory, metallography and interfacial physics. In-depth study of the reaction mechanism between the electrode layer and the ferrite, quantitative indicators of lead-free solder and the metal electrode dissolution mechanism has been done. Researches show that:active metals like Cr and Ni, are capable of capturing oxygen atoms from substrate, and they are chosen as the transition material, there will be an oxide of the material at the metal-ferrite interface, it is this layer of metal oxide greatly improve the adhesion of the film. A well-designed metallization is required to provide necessary adhesion, high-temperature treatment.3. Auxiliary laser etching was first proposed to solve the problem of small-sized inductor metallization. Results of its application showed great advantages over original mask sputtering method:both in producing rate and metallization quality.4. Based on Experimental results, we designed and installed a magnetron sputtering metallization production line, completed PLC controller programming and monitoring software. The production line has been successfully put into manufacturing. The implementation showed that it has reduced costs by more than60%, and saved more than40%of the electricity compared to electrode coating. Product quality has reached the international advanced level, created significant economic benefits. Two invention patent has been published.