Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [stack-up]

60 questions
11
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3 answers

PCB stackup for an 8-layer PCB

We are considering to have the following stackup for an 8-layer PCB we are designing. What we want with this stackup is to route the signals with approx. rise time of 3ns on layer 6 using a separation between traces of 8mils between them to get a…
Aldanajaramillo
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7
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3 answers

4 Layer PCB stack up

I have designed a lot of 2 layer PCBs so far and am trying to slowly move to 4 layer versions. One of the major challenges I'm currently facing in that aspect is the acceptable stack up of the layers of the PCB. I'm currently using the following…
darthMaul
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7
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1 answer

Real current return path

The theory says that the current return path at high frequency is on the reference plane right under(or above) the signal trace. I know it is true and I have always assumed it was, but I would like to understand it properly. My trouble is about it…
damien
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6
votes
3 answers

One versus two plies of prepreg?

I need to specify the construction of a 4-layer PCB with transmission lines on the outer layers and planes on the inner layers. I need to control impedance and propagation speed. The target prepreg thickness is around 0.2mm (7-8mil). I can achieve…
Michael
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5
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1 answer

Routing impedance controlled signal with a power plane as reference

Assuming i chose to route an impedance controlled signal with a power plane as a reference plane instead of ground (microstrip or stripline), and assuming i'll make sure the signal won't cross power planes. Does it matter if the reference power…
YossiK
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1 answer

PCB Stackup - Current return path

It is a well known fact that high speed signal would have return current path on the plane right beneath it's PCB trace. Suppose we have 4 layer stackup, SIG-GND-PWR-SIG with dielectrics CORE-PREPREG-CORE respectively. Difference between core and…
Bip
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4
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3 answers

PCB design for high-frequency differential lanes (PCIe and USB)

I have designed an M2 adapter which converts from KeyE to KeyM. Practically this means my board can be inserted into a KeyE slot, and it can host a KeyM SSD. Gray rectangle is the KeyM socket on my board: Design involves 10uF caps on 3.3V on both…
Daniel
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4
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3 answers

6-layer stackup

Edit 3: I used the following Stackup - in respect to recommendations provided by my board house and the responses to this question. This is a 6-Layer, 0.5mm thick, 1 + 4 + 1 HDI board (Copper thicknesses are not correct in the image). EDIT 2: As…
ElectronicsStudent
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4
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2 answers

Ethernet ground multilayer pcb

I'm currently re-designing a 12-layer pcb. The only thing I am still struggling with is the routing of the ethernet. The layer stackup is as follows: Top Layer GND_1 MidLayer_1 PWR_1 MidLayer_2 GND_2 PWR_2 Midlayer_3 GND_3 Midlayer_4 PWR_3 Bottom…
Remco Vink
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4
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2 answers

AC signal and ground plane with another trace passing between - is this bad?

In learning about reducing a circuit's EMI emissions, I've learned the importance of a ground plane, in that it allows the current-return for an AC signal in an adjacent layer to flow directly under that signal's trace, due to that return-path…
beammy
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3
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3 answers

JLCPCB 4 layer stackup

JLCPCB 4 layer pcb stack mentions a copper core as the image attached. Is this a error or the layer 2 and 3 are wittingly in short? This image makes no sense... Taken from:…
Luis Carlos
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1 answer

are there any differences between referencing signal to VCC or GND planes?

In my first high-speed PCB design, I have an LPDDR3 RAM and my PCB have 6 layers with the below sequence: 1-Signal 2-GND_Plane 3-Signal 4-Signal 5-VCC_Plane 6-Signal the region between the SOC and RAM is totally covered by VCC-DRAM in the VCC_Plane…
Milad
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3
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1 answer

High speed signal return path in a stack-up with multiple ground planes

Consider the following 6-layer stack-up for a mixed signal board. 1: Top --- analog signals, components --------------- ================================================== (0.20 mm) 2: GND --- return path for analog signals ----------- …
sergej
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3
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2 answers

Four layer PCB stackup with thick prepreg layer: how is it useful?

I've been working on a four layer board with 100Ω differential pairs. Prototypes were built, impedance was measured, things were fine. But then as I tried to move the production to a different facility, I discovered that some PCB fabs use a much…
Jan Rychter
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3
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Are there any disadvantages to having a thicker PCB?

Similiar to the question What are the advantages and disadvantages of thinner PCB thickness (<1.6 mm)?, but going the other way. If we look at the picture in the previous question's answer, we have the following If I increase the…
efox29
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