Electronics & Electrical Engineering Forum:
Ask A QuestionGeneral
Multilayer board design
I want to design a multilayer board (it has 6 layers) with the Altium designer software, but I haven’t had a lot of experience with the multilayer techniques. Can anyone help me understand how I can organize the partition of the layers and how should I define the size of the track width?
Here are a few items to think about that will help you define the board stackup.
1. How many power/gnd planes do you need in the design. I would try and avoid split plane layers to begin with.
2. Here is a common board stackup where all 4 routing layers are impedance controlled. A designer can choose the distance between each signal layer and it’s reference plane and still get a typical board thickness by adjusting the laminate between layers 3 and 4. Most board houses will choose the stackup distance for you if you let them. But you should have something in mind as you choose the trace width to match you impedance.
__________ S
__________ G
__________ S
__________ S
__________ G
__________ S
3. It looks like Altium Designer has some impedance calculators built into the software that will assist you in choosing a trace width. See this link
To read up more on 6 layer stackups check out Henry Ott’s website
Thank you for your reply,
Well, my board is based on the dm6437 processor it have : 3 powers: 1.2 V , 1.8 V and 3.3 V and ground.
It seems that I should use the split plane, but is it good to split the power plane into three parts?
Also is there a configuration of pads between the 6 layers? and what’s the number of pads that I should make between the different layers?
You could use on of your signal layers as an additional power layer if you have enough room to route your board. Can you upload a schematic? Also do you have a board size that your targeting?
_______ S
_______ 1.8V
_______ 1.2V
_______ S
_______ 3.3V
_______ S
Well,
The borad is sized (38mmx38mm).
About the schematic we have divided the card into 10 sub-schematics (sorry, I cant send them because our company concideres these schematics as a company secrets).
This board contains a processor, RAM memory, Flash memory, Secret memory and a lot of capacitors ans resistors.
The major problems right now are : How can I configure the pads between layers, how can I define the trace width..