Study On Broad Band MMIC Package Design And Related Processes

In recent years, MMICs (Monolithic Microwave Integrated Circuit) have been widely used in fields such as wireless communication, radar and GPRS. MMIC products are often shipped in packaged form, which leads to higher system level assembly efficiency, integration and reparability, as well as lower cost, compared with traditional bare die products. While offering its electrical, thermal and mechanical functionalities, MMIC package always degrades the performance of the packaged chip, therefore, the main challenge for MMIC package design is to minimize the impact to chip performance while realizing package functionality and reliability, at the same time, package size should be small and cost should be kept low. Traditional MMIC packages utilize low dielectric loss ceramic material and related co-firing, metallizing processes, excellent performance can be achieved yet the process is complicated and cost is relatively high. Recently, some organic substrate materials for high frequency and RF application have been gradually brought into use in MMIC package for their low cost and compatibility with traditional PCB manufacturing process. This paper develops a MMIC package structure manufactured from Rogers 4003 organic high frequency substrate material and PCB manufacturing process, which has excellent electrical and thermal performance, and is compatible with SMT technology. This package can be used for X&Ku band driver amplifier and other MMICs. Firstly, package material and related processes are selected based on available resources. Package structure is preliminarily designed according to studying on existing data. Then, package structure, especially the signal transmitting path structure is optimized using 3D electromagnetic simulation and microwave circuit theory. Effect of package lid is also studied.Lastly, actual package structure is manufactured, packaging process is researched and completed, and performance of packaged MMIC chip is tested. Test result shows that packaged X&Ku band driver amplifier MMIC has a return loss of less then -10dB and again of higher than 20dB, along 6--18GHz, which corresponds well with bare dieperformance. Package design is preliminarily successful.