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April 5-7, 2022|Santa Clara Convention Center| Santa Clara, CA
Xiaoning Ye (Principal Engineer, Intel)
Subas Bastola (Technical Lead, Intel)
Amy Luoh (Technical Lead, Intel)
Vijay Kunda (Board Development Signal Integrity Engineer, Intel)
Gary Brist (Principal Engineer, Intel)
Aravind Munukutla (Failure Analysis Engineer, Intel)
Location: Ballroom G
Date: Thursday, April 7
Time: 12:15 pm - 1:00 pm
Track: 04. Advances in Materials & Processing for PCBs, Modules & Packages, 07. Optimizing High-Speed Link Design
Format: Technical Session
Theme : Data Centers
Education Level: All
Pass Type: 2-Day Pass, All Access Pass
Vault Recording: TBD
Audience Level: All
The industry demand of lower loss PCB material is increasing. Using exotic dielectric materials with a very low loss tangent is often necessary, which leads to the result that the signal loss attenuation due to copper foil becomes the dominant factor. There are various publications showing the impact on insertion loss using copper foils with different level of smoothness. However, one of the often overlooked aspect is how the copper surface treatment during the PCB fabrication can impact the insertion loss. In this study, we built several electrical test vehicles with various surface treatments, using a typical 16-layer PCB stackup used in Intel Datacenter systems. The insertion loss of test coupons were measured up to 40GHz using the new IPC test method 188.8.131.52. Three types of surface treatments are studied. We also included different PCB materials, different copper foil types in the investigation. Multiple boards were constructed for each configuration to have enough data samples. We will quantify the impact of surface treatment on insertion loss, and report high-resolution cross-sectional analysis of the test samples, to reveal how the surface treatment change the copper profile during the lamination process. Electrical modeling based on the cross-sectional analysis will also be reported.
We will show results of test vehicles (2 types of materials, 4 types of copper foils, and 3 types of surface treatments) to reveal the importance of surface roughness on insertion loss reduction. It is also shown that low-etch and/or non-oxide surface treatment can provide significant ROI for Insertion loss reduction.