Copper Roughness and Signal Integrity

There's been a lot of talk over the years regarding copper roughness, yet few hardware engineers or signal integrity practitioners have a detailed understanding of this key contributor to high-speed signal loss.

To keep you from getting surprised by previously untracked contributors to insertion loss, we will discuss 10 critical things you need to know about copper roughness and their impact on board costs and signal integrity.

1. There’s no standard terminology governing copper roughness — it’s left to individual vendors
2. High speed materials use primary/secondary/tertiary copper foil types — at different price points
3. There are multiple ways to measure roughness
4. There are several ways to model loss mathematically — which one is best?
5. Loss from copper roughness is more controllable than skin effect
6. Understanding prepreg/process - side roughness
7. There are multiple fabricator process treatments that affect roughness
8. Foil selection dominates loss, as compared to process treatments
9. Plating’s effect on copper roughness
10. Practical advice for managing roughness, loss, and cost