Why ppl use ow thickness boards,eg. 1mm instead of 1.6mm?

[FatPanda]

4Layer PCB

Why some PCB designer prefer to use low thickness board, for example 1mm instead of 1.6 mm? an example for this issue is HDD board!

 

[Johnson]

4Layer PCB

I suggest that it is the impedance matching problem, but 1mm bards has less reliability

 

[FatPanda]

4Layer PCB

What about mother board, how many layer is common for them?

 

[Johnson]

4Layer PCB

for home user the main concern is price so they are mostly 4-layer board but for industrial applications they may use 8 or 10-layer PCBs.

 

[chinta]

4Layer PCB

for consumer boards, you have to minimise the layer count, so that you can get the cheaper boards. For mother boards, anywhere from 8 layers to 16 layers or so..