What is the difference between clearance and creepage?
Clearance is the shortest distance in air between two conductive parts. Creepage distance means the shortest distance along the surface of a solid insulating material between two conductive parts.
What is creepage and clearance in PCB?
Creepage is the shortest distance between conductor traces on a PCB along the surface of the insulation material while clearance is defined as the minimum distance through the air (line of sight) between two conductor traces.
Why do we need creepage distance?
A proper and adequate creepage distance protects against tracking, a process that produces a partially conducting path of localized deterioration on the surface of an insulating material as a result of the electric discharges on or close to an insulation surface.
Why is there a need for creepage and clearance?
Creepage and clearance is ultimately about safety and meeting regulatory standards, regardless of the system design. And, the ongoing trends to reduce PCB size and increase density become a design challenge when these smaller, denser PCBs incorporate high voltage circuits.
Can a creepage distance be greater than clearance distance?
A creepage distance can’t be less than the clearance distance; in other words, the shortest creepage distance will be equal to the clearance distance. Connector manufacturers can increase creepage distances by adding grooves, notches, or plastic planes (i.e., walls) on the connector’s plastic insulator.
Which is the highest voltage for creepage and clearance?
A working voltage is the highest voltage across any particular insulation when the equipment is subjected to a rated voltage. This definition is stated in various international standards, including IEC 950 and EN 60950. The creepage and clearance values are calculated by determining the working voltage under a certain operating voltage.
How much creepage should be allowed between primary and ground?
A 4-mm creepage distance should be allowed between primary and ground. If these dimensions are allowed for during the design stage, there is a high probability that the product will gain approval with respect to creepage and clearance when the final product is submitted for test.