After noticing the other questions you have posted in Comm & Electronics, I would like to know what class we are assisting you in passing, I would like credit too . The optimum trace "width" (I don't think you meant thickness) and trace spacing are dependant on many variables. Three factors that come to mind are; 1) What impedance do you want the trace to be. 2) How much current will the trace carry? 3) What is the highest voltage the trace will carry?

There are formulas available where these and other parameters can be entered, and the optimum width and/or spacing will be given.

Good luck with class.

Tom

Thanks for your comment . yes i meant width, and please I want these formulas.

I repair PCB.

Google "trace width calculator", and you should have many choices to choose from. I'm not sure why you would need to calculate trace widths to repair PCB's .

Tom