Help with PCB routing for nixie tube clock

[halenthir]

Hello everyone,

I'm new to this forum and I started electronic only months ago, so please don't hesitate to post your remark.

For my first project, I want to design a vintage alarm clock using nixie tubes, with 6 IN-14 for the digits and 2 IN-3 for the dots. It is an educational project for me.
I choose to design 2 separate boards for this project, the first one is used for nixie tube multiplexing and the second for the alarm logic, the speaker and the RTC. For now I choose to start with the first one (tube multiplexing).
I created this post to get some advice concerning the PCB design, but if you want to make comments on the schematic, I will gladly read those too.

I never used an EDA software in the past, so I watched some videos and read articles before starting, but I still have questions about PCB design:

1) I use 170V DC for the tubes, is there any precaution that I should ensure for a safe design?

2) What trace width should I use?

I used a trace width of 0.3mm and 0.4mm (arbitrary) for the main power source (+170V).
I intend to order the PCB online after finishing my design.
The website I wish to use offers 1oz copper weight by default.
I checked if this is enough with the first calculator found on google.
Given the longest path in my design is 160mm and the low consumption of nixie tubes, it seems okay.

3) I had a difficult time routing my PCB, I use a lot of vias.
Do you think this will cause an error or lead to interferences?
Do you have advice to make it simpler?

4) I use a 2-layers PCB, should I use a 4-layers one instead?
Also, is it me or 4-layers seems very expensive?

5) Should I pay attention to clearance and creepage given the high voltage?
The clearance is set to 0.152 but I cannot find where to set the creepage.
Is the creepage usually a global parameter on EDA softwares?
I still don't clearly understand what they are and how they appear on the PCB.

6) Some traces are close to component leads or other traces. Can this cause errors?



7) Some trace are very long on my PCB, around 160mm. Is it a bad idea?

Also I use this weird pattern to connect all the nixie tube cathodes together:



I never seen something like that on a PCB, so I wonder if this is bad.

8) Do I miss something?

9) Also, if you have any suggestion to save money, I will gladly ear it :-).

Here is the link to my project: https://easyeda.com/halenthir/nixie-clock

Thank you for your feedbacks!