High-frequency characterization of direct plated copper metallized substrate and its application on microwave circuit

Direct plated copper (DPC) metallized substrate is introduced, characterized, and demonstrated in this paper. The proposed DPC metallized substrate has the main advantages of high-frequency characteristics and excellent thermal management, due to the use of ceramic substrate and metallized copper conductor. Besides, the DPC process also provides high circuit density, fine pitch, and low cost potential compared to other technologies, like direct bonded copper (DBC), Low-Temperature Cofired Ceramics (LTCC), and High-Temperature Cofired Ceramics (HTCC) processes. Therefore, to characterize the electrical properties of DPC substrate for high-frequency applications, a simple extraction method was adopted to carry out the correlated values of dielectric constant and dielectric loss at Ku-band. However, to validate the extracted parameters, a 10-GHz parallel-coupled line band-pass filter (BPF) was demonstrated by using the presented DPC substrate. This BPF has measured insertion loss of only 0.5dB and return loss of above 10dB in the passband. It obviously proved that the DPC metallized substrate is very capable for RF module packages and microwave components, with its excellent low loss performance.