Hiroshi Ono, Ayumu Tateoka,
Shinichi Obata, Hiroaki Kurihara
New Product & Process Development,
Mitsui Mining & Smelting Co., Ltd.
Oak-Mitsui Technologies LLC
Large data transmission continues to increase at the rate of 20% worldwide annually due to live video streaming, cloud storage, PDA usage, IOT, and other technologies. Electronic devices are getting smaller yet required to accommodate higher speeds and good signal integrity. With 5G technology on the horizon there is heightened concern for signal loss affecting product performance. It is more important than ever to analyze loss factor at the earliest design stage. This analysis is done for the PCB materials by manufacturing electrical test coupons prior to building the PCB and evaluating the electrical performance. These coupons are designed and built with (TEG, test element group) structures which are ideal for measuring transmission loss. However, often these test PCBs use different lots of raw laminate materials which yield different results. Why? This study examines possible factors for these inconsistencies such as etched signal trace shape, surface treatment, and grain size.
It was found that issues that were not as problematic when device operating speed was in the few GHz range are now critical with speeds going up to 10 plus GHz. Impact of skin effect is prevalent at higher frequencies and effects of materials and inconsistencies in processing can no longer be ignored. As far as trace shape there are 4 sides and both the contributing factor of the circuit and bonding sides need to be taken into account. Thus, finer treatment than brown oxide and ways to bond without roughness treatment would be required in the future. As these areas are not addressed in the PCB CAD drawing, design engineers working on high speed applications need to understand the importance of these factors and select materials as well as control the manufacturing process.
Initially Published in the SMTA Proceedings