Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

PCB Core Laminate Thickness

Status
Not open for further replies.
M

mayd85

Junior Member level 3
Joined
Apr 10, 2013
Messages
30
Helped
3
Reputation
6
Reaction score
3
Trophy points
1,288
Activity points
1,505
Hi,

I am designing a PCB for which I have to mention the stack up and do some impedance calculations. I have a basic question. When I say that I have a core with a thickness of 200 um, does this 200 um include the thickness of copper as well? I mean if i am using 35 um copper, is the cross section 35-200-35 or 35-130-35 (making it 200 um)?
 

The thickness that is specified is typically the thickness of the dielectric substrate, and does not include the outer copper clad thickness. So a 200um controlled thickness board with 35um (0.5oz) copper will be 270um thick overall. (Cross section = 35-200-35)
 
  • Like
Reactions: mayd85

    M

    mayd85

    Points: 2
    Helpful Answer Positive Rating
mayd85 said:
Hi,

...does this 200 um include the thickness of copper as well? ...
Click to expand...

Within a multilayer, copper sinks into the adjacent Prepreg. The core is still 200µ after pressing, but a 200µ prepreg has 130µ provided you have almoust no copper, which is true for layers with just a few routes. If you have copper planes with near 100% copper area, the prepreg will have 200µ - the difference is proportional to the percentage of copper, and this must be calculated for the layer stack, else the resulting thickness will be wrong: for a ml with 4 inner signal layers by about 140µ.

sy Reinhard
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top