when a multilayer pcb design is required:

[Dinos Tsakalakis]

Hallo , i know that this question sounds silli butt , i have to make a pcb design and i need to take a descision of how many mayers i must use ,and i also wonderring if there are any restrictions ,of adding a layer ,and  if the pcb can't be done only with one layer;

Thank you,

[Bassman59]

Hallo , i know that this question sounds silli butt , i have to make a pcb design and i need to take a descision of how many mayers i must use ,and i also wonderring if there are any restrictions ,of adding a layer ,and  if the pcb can't be done only with one layer;

Thank you,

Well, for starters there's no real benefit to doing a single-layer board except for the absolute cheapest and lowest-performance designs. Managing the wire jumpers needed to get signals around is a pain. A two-layer board doesn't add cost and makes your life easier.

The only restrictions for adding layers are that you have to add them in pairs, and that adding layers adds cost.

Any PCB layout program you'd care to use should manage multilayer boards without any problems.

[ANTALIFE]

If it's a hobby project, what ever you are comfortable with

If it's for a product, then suggest having a look at Keith Armstrong's material like this. There is also this video from . Basically if you want to make life easier for yourself (EMC wise), then you need to use at least a 6-8 layer board for a relatively complex design

[james_s]

I generally consider a double sided board to be a single layer. Maybe this is not technically correct but when I hear multilayer PCB I think multiple layers of PCB sandwiched together with buried traces in the inner layers. These days all of the hobby level PCB suppliers charge the same for single and double sided.

[geggi1]

Depending on signal-levels and noise immunity you will normally be good with dual layer.
Many of the reasonable priced EDA packages will only let you make singel or dual layer.
Dual layer is more flexible than single layer.
Single layer is simpel to do if you etch the board at home but gives no benefit when getting manufactured boards.
Single layer demands more planning of components to prevent wire jumpers.
Dual layer PCB is possible at home but its a lot of hassle.

My recommendation is:
Single layer only on simple home etched boards. (pre production prototypes)
Dual layer everything else unless there is special requirements.

[asmi]

Since 4 layer boards now are so cheap, almost all of my boards are 4 layers (and more). They make layout so much simpler, and they are great for signal integrity.