IPC Class 2 VS Class 3: The Different Design Rules

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Source: IPC Class 2 VS Class 3: The Different Design Rules | Sierra Circuits Blog

Randy's Comments:

IPC specs do not dictate the pad size. It's all about the finished minimum annular ring.

The IPC criteria is 2 mil finished annular ring on external layers and 1 mil minimum on the internal layers. Class 3 pad sizes > drill + 12mil are imposed by fabricators who have > 4 mil layer to layer tolerances.  

It comes down to fabricators capability and process tolerances.  Smaller pads can be used if the fabricator has tight layer to layer tolerances.  

Just be aware that tighter (smaller) tolerances will impact yields and the costs will be passed to the customer.

The other noteworthy Class 3 requirement for vias is the via barrel wall plating must have an average minimum thickness of 1 mil.  Stringent class 3 fab notes will specify an absolute minimum thickness for the barrel plating.

That's it !

Estimating Ground Bounce

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Source:
How to estimate ground bounce in a connector- Rule of Thumb #8 - EDN

That's it !

PCB Signal Integrity: Understand Coupling - YouTube

PCB Signal Integrity: Understand Coupling - YouTube:

Home - GigaTest Labs

Home - GigaTest Labs: "The Industry's leading Signal Integrity Company. Serving the Electronics Industry with Engineering Excellence."

'via Blog this'

Using Remote Sensing - Vicor

Source:

Using Remote Sensing to Ensure Accurate Point of Load Voltage Control | VicorPowerBlog: 

'via Blog this'

KwickFit - Fixed Size PCB Array Calculator

Fixed Size PCB Array Calculator:

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'via Blog this'

Calculate Distributed Line Length

Distributed element wavelengths occur at fractional wavelengths.

1/4 for Digital Paths
1/12 for RF Paths
1/16 for Analog Paths

Use the Saturn PCB Toolkit v7.05 to calculate lumped / distributed wavelengths.

Note that 1/Time = Freq and 1/Freq = Time, they are reciprocals.

In the Saturn PCB Toolkit select the Wavelength Calculator tab.

Example: 

Select the Period to enter the edge rate transition time. 

Enter 1nS for the Risetime period. (10% to 90%)
Enter the Er Eff (effective Er (Dk) Dielectric Constant.
Set Wavelength Divide to 1/4 Wave Length.

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As shown above the distributed 1/4 wavelength = 1.46 inches for a rise time of 1 nS.

Paths shorter than this length are lumped lengths and longer lengths are distributed length paths. Distributed lengths should be impedance controlled paths.

Something for the RF Geeks:  Quarter Wave Tricks

Something for Everyone: Admiral Grace Hopper Explains the Nanosecond

Who is Grace Hopper? - YouTube

That's it !