Conductor Surface Roughness - Nice short post by Lee Ritchey to sum up what you need to specify on your fab drawings.

A discussion over on the SI-LIST on copper roughness triggered Lee Ritchey to write a nice summary of the state of things when signals are fast enough that you are concerned about losses at high frequencies. You can read it in full here, but in short this is the essence:

I specify copper roughness on all of my fabrication drawings where I am concerned about losses at high frequencies.

To do that,…

Glass Weave for 10+ GBps Stackups is important - at 25 Gbps it is a MAJOR issue. Eric Bogatin and Lee Ritchey explains.

With transmission speeds of 10 GBps you have to be careful not to have too much line-to-line skew in the differential channels. The glass weave is a big contributor here. When you go to 25 Gbps, this is a MAJOR issue that you NEED to address.

Two recent…