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Vias dimension

Roibert , 09-26-2018, 03:05 AM
Dear Forum

I my
4 layer PCB
,Im using vias with diameter=
- pad= 0.45mm, for signal track.
Normally beetwen 2 ground plane I use the same vias, randomly positioned in this plane.

Questio is: is better use the same vias for gnd plane, or could be better use bigger vias Es 0.4-0.7mm or more?

The attach photo clarify what I means: 2 vias for GND and 2 vias for UART.

Thanks for your time

mairomaster , 09-28-2018, 02:44 AM
I don't think the via size matters too much for the ground stitching. I would use the same size as the signal vias just to reduce the number of drill pieces used for the manufacturing.
Roibert , 09-28-2018, 03:24 AM
Thanks for reply.. Just again some curiosity:

-So , 2 kind of vias increase the cost ?

-From a phisical point of view, if there is a chip with a pin going to ground,and we need to go using vias around this pin, what could be better :

A) 1 vias with hole size diameter =5mm (so area going to ground is lengh is 2*pi* 2.5 * H vias ) , or

B)2 vias near them but with half diameter (in this case 2 with diameter 2.5mm , so the total area is the same as case A )

Dimensio in example are invented..not so important...

Thanks for your itme

mairomaster , 09-28-2018, 08:36 AM
Yes the more drill sizes you have the more expensive the board is to manufacture, it might be not a significant increase though, it depends on different factors. For simple 2/4 layer boards that might not even be a factor at all or I should rather say taken into account for the particular board.

In general, if you need to have more ampacity, it's more efficient to use more vias rather than bigger vias.

robertferanec , 10-01-2018, 12:24 AM
I agree with @mairomaster.
Also I would like to add. According my info from PCB manufacturer, today's machines can use many different tools (they have big cartridge to hold number of tools), so number of tools is not going to influence price as much as it used to be couple of years ago (old machines only could hold limited number of tools and they had to be replaced during manufacturing).

What I would recommend, if you have enough space on your PCB, do not use holes smaller than 0.3mm. This can make your PCB cheaper. Here is example from PCBWay online calculator - 4 layer PCB with 0.3mm holes will cost 49 USD and 4 layer PCB with 0.2mm holes will cost 137USD

Roibert , 10-02-2018, 06:05 AM
Thanks very much for the time you spend for me...I really never noted this difference.

Thanks again

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