A Comprehensive Study on Signal Integrity of Build-up Film Applied to IC Substrate

Cheng Zhong1; Wenbo Chen2; Weikun Kong1; Shuhui Yu1; Jibao Lu1; Rong Sun1

10.1109/ICEPT59018.2023.10492342

2023-08-11

2836-9734

979-8-3503-3882-9

2023 24th International Conference on Electronic Packaging Technology (ICEPT)

8-11 Aug. 2023

Shihezi City, China

With the advent of high-speed digital era and rapid development of 5G mobile technology, electronic devices need to operate in high frequency and high-speed scenarios. Signal integrity problems such as transmission loss, reflection, impedance matching and crosstalk between signal lines become more serious. As the carrier of integrated circuit (IC) packaging, IC substrate is developing towards the direction of high performance and high integration. As an insulating medium used in IC substrate, the build-up film (BF) has great advantage for building fine lines. In order to improve the quality of signal transmission and ensure the normal operation of electronic equipment, it is necessary to study the influence of BF on multilayer substrate in the process of signal transmission.In this paper, we mainly focus on transmission loss by electrical simulation, different materials and structural parameters in both single-layer and multilayer substrate are discussed. Firstly, in single-layer differential lines structure, it is found that dissipation factor (Df) of BF has a greater influence on insertion loss (S21), while dielectric constant (Dk) of BF has little effect on S21. This is mainly due to the proportional relationship between Df and the dielectric transmission loss part of S21. Then, the benefit of line width and line distance adjustment on reducing transmission loss is also studied. However, it is found that both line width and line distance have little influence on S21 in single-layer differential lines structure. In addition, we further investigate signal integrity problems in multilayer substrate, focusing on the influence of the through via structure between different layers on signal transmission. Obvious resonance occurs in the multilayer structure containing through via, which is observed by both S21 and return loss (S11). The mechanism of resonance is analyzed in detail, it is also found that the effect of resonance can be optimized by altering the structural parameters of the hole such as increasing the aperture. Meanwhile, it shows that Dk and Df have little effect on S21 and S11. Based on the above analysis, we conclude that BF with low Dk and Df is of great significance for reducing transmission loss in high-frequency scenarios, the underlying mechanism and structural effect are also discussed in detail. This study will provide theoretical guidance and suggestions for the signal integrity of IC substrates with BF.

其他

1.Shenzhen Institute of Advanced Technology, Chinese Academy of Science Shenzhen Institute of Advanced Electronic Materials, Shenzhen, China
2.Shenzhen Institute of Advanced Technology, Chinese Academy of Science Southern University of Science and Technology, Shenzhen, China

Cheng Zhong,Wenbo Chen,Weikun Kong,et al. A Comprehensive Study on Signal Integrity of Build-up Film Applied to IC Substrate[C],2023.