PCB Clearance Suggestion

[sakibnaz]

Hello.

In PCB design ... I am quite confused about determine PCB clearance. Generally my default Signal lines are 10mil Trace Width and 10mil Clearance.

Now what Clearance I need to use for a +12V Line which may draw max 3A? I set 40mil Trace Width for this high Voltage Line, is 40mil good enough to pass 3AMP?

Can anyone advice me ... about calculation of Trace Width and Clearance based on Voltage Level and AMP ratings?

Thanks in advance.

Regards.
Sakibnaz.

 

[awaw]

Look here.
Or here.
There are many others.
Don't worry about interwire clearances until your voltages are not in kV range. Use usual interwire clearances inherited from your main design rules and based on manufacturers possibilities.

 

[praveenlb]

Hi,
trace width is depends on current . and spacing is depends on the voltage.
as per ipc standreds minimum trace width for 1 amp current is 15 mil. and 100 v requried 1 mm spacing

for more details refer PCB Trace Spacing Calculation for Voltage Levels
Regards
Praveen

 

[marce]

Pollution level, usage etc etc
**broken link removed**

 

[loosemoose]

For calculation current, see the Saturn calculator here PCB Via Current | PCB Trace Width | Differential Pair Calculator | PCB Impedance.
As for spacing you should start worrying about it when it is 60V. There are many requirements for safety. see UL-CSA 60950.

 

[Rapport]

Since 3A is much higher current capability, 40mil is not good enough to carry 3A current. Even if you use 2Oz copper, outer layer needs 35mil and inner layer needs 75mil as trace width. Trace width I suggested here is with 10deg max ambient temp rise. It's better to go for plane shapes (with 2Oz as base copper) for 3A current and 25mil clearance between plane to plane is more sufficient for 12V line.

 

[sakibnaz]

Thanks for your advice Rapport.

I completed my design and finally used 40mil width and 20mil clearance for the high voltage lines.

Regards.
Sakibnaz.

 

[marce]

I would download the Saturn PCB toolkit and have and use their calculator:
https://saturnpcb.com/presentation.htm

 

[tpetar]

For higher current needs on PCB, You should add soldering material on existing high current tracks to increse square area of that tracks. The same situation is with legs of high current MOSFETS and other power transistors legs.

or

If you have some free area You can expand track on PCB.


If tracks have small square area and they are under current needs, You will get heating of PCB and in some cases burnout tracks and malfunction of device. You can check temperature of some high current tracks, best way for observation of PCB is with FLIR cammera.

 

[marce]

Dont add soldering material on top of traces it cannot be controlled properly. Use the correct size of copper or hard wire.
3A is NOT high current.

 

[tpetar]

Dont add soldering material on top of traces it cannot be controlled properly. Use the correct size of copper or hard wire.
3A is NOT high current.

How You mean 3A is not high current for 0,254mm (0.01inch) wide track ? This track is like fuse for 3A DC @12V!!!


To see original needs :

Generally my default Signal lines are 10mil Trace Width and 10mil Clearance.

Now what Clearance I need to use for a +12V Line which may draw max 3A? I set 40mil Trace Width for this high Voltage Line, is 40mil good enough to pass 3AMP?

40mil is about 1,016mm or 0.04inch (if I make good conversion).

1mm wide track for 3A (we dont know length, utilization of that track-working time, impulse or constant current, freq, thickens of copper track, and what is allowed temp raise, ambient temp, heating parts near or on other side of pcb, its layer outside or inside multi layered PCB) ?

We need for 12V @ 3A at least 40mil track, but this is on edge!

I dont see how 3A @ 12V is not high for this?


One of PCB track calculator :
**broken link removed**

Impedance, crosstalk, current, thermovia calc:
https://www.skottanselektronik.com/

You can find lots calculators on Internet, just google.

Dont add soldering material on top of traces it cannot be controlled properly.

Can be controlled with flux without problem. But like all other things in life expirience is needed. You can see in lots of commercial devices PCB that situation, that high currrent track are hardened with additional soldering material, to prevent overheating and burning of track.




Like I say in earlier post I think that is best to make PCB track wide according to the needs if there is free area on PCB.