See: [https://easyeda.com/forum/topic/Setting-Trace-Space-on-Differential-Pair-Routing-8b2abd9a502c48dc856f19617cefbb2e](https://easyeda.com/forum/topic/Setting-Trace-Space-on-Differential-Pair-Routing-8b2abd9a502c48dc856f19617cefbb2e)<br> <br> "Would also like information on via size choices ..." What information?

What sizes are available?    I will use what you have available. Can I just use any number that pops into my head, or am I constrained to specific sizes you have on hand? How might I choose depenent on trace width? How do diameter and drill size relate? Should diameter always be a specific multiple of drill hole size?

"What sizes are available?    I will use what you have available. Can I just use any number that pops into my head, or am I constrained to specific sizes you have on hand?" Please refer to: [https://jlcpcb.com/capabilities/Capabilities](https://jlcpcb.com/capabilities/Capabilities)<br> <br> "How might I choose depenent on trace width?" Depends on the current you want to carry through them or - if it matters to you - the maximum impedance you can tolerate in the signal path. The latter is beyond the scope of help in this forum but is essentially "as many as you can fit in". The former is basically dealt with by adding enough vias of any diameter that the total cross sectional area of the through-plating is the same as that of the track in which they are inserted. The cross sectional area of a trace is W*Tt where W is the trace width and Tt is the track thickness (which is the copper thickness, Tc, plus the small amount of plating thickness added during the through-hole plating step and which may be slightly greater than the finished through-hole plating thickness). Copper thickness is also given in the link above: The cross sectional area of a single through-plated circular hole is pi*( (Dd/2)^2 - (Dp/2)^2 ) whereDd is the hole diameter that is drilled before plating and Dp is the hole diameter after plating. Let the through-hole plating thickness = Tp Remembering that the difference in hole diameters is twice the plating thickness: therefore Dd = Dp+2*Tp "How do diameter and drill size relate?" Check with JLCPCB but I understand that they drill plated-through holes so that the finished (plated) hole diameter equals that specified in the PCB design so the drill diameters will be slightly larger. The plating thickness, Tp, is given here: [https://easyeda.com/forum/topic/How-thick-is-the-through-plating-of-a-through-hole-pad-0690fda822f84520a9dbddc662fb8dcf](https://easyeda.com/forum/topic/How-thick-is-the-through-plating-of-a-through-hole-pad-0690fda822f84520a9dbddc662fb8dcf)<br> <br> "Should diameter always be a specific multiple of drill hole size?" No reason for it to be. Filling the vias with solder helps reduce their DC and thermal resistance but not their high frequency resistance due to skin effect.