PCB Risk Assessment & Management 2

Question 1

What risk does impedance discontinuity at a via present in high-speed PCB design?

Accepted Answer

Signal reflection and degradation at the transition point

Answer

Impedance discontinuities at vias cause signal reflections that degrade signal integrity, especially above 1 GHz.

Question 2

Which design practice mitigates the risk of crosstalk between adjacent signal traces on a PCB?

Accepted Answer

Maintaining a spacing of at least 3× the trace width between signals

Answer

Maintaining at least 3× trace-width spacing (3W rule) significantly reduces capacitive and inductive coupling between adjacent signals.

Question 3

A PCB will be used in a high-vibration automotive environment. Which risk should be prioritized during component selection?

Accepted Answer

Mechanical shock and vibration ratings of components and solder joints

Answer

Vibration can cause solder joint fatigue and component failure, so mechanical ratings must match the application environment.

Question 4

What is the primary risk of using a single shared power plane without proper decoupling on a mixed-signal PCB?

Accepted Answer

Digital switching noise coupling into sensitive analog circuitry

Answer

Without adequate decoupling and power plane partitioning, high-frequency switching noise can propagate and corrupt analog signals.

Question 5

Which risk is introduced when controlled impedance traces are routed too close to the board edge?

Accepted Answer

Impedance variation due to reduced dielectric boundary effects

Answer

The dielectric field extends beyond the trace, and proximity to the board edge alters the effective dielectric constant, shifting impedance.

PCB - Design Practice Test