Questions tagged [stack-up]

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60 views

Changing layers order while keeping stack-up

I have progressed really far with my project until I found out that the manufacturer had set different reference planes for my signal layers than the ones I intended to do. Here is the stackup that I ...
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0answers
99 views

Four-layer stack-up in PCB design

Folks, I am planning to design 4-layer PCB. I came across the following website which has excellent pointers: ...
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1answer
60 views

Which PCB stackup is better for noise immunity and why? [closed]

Is a two layer board with a Signal plane and Ground plane better? Or is a four layer board with Signal, +Voltage, -Voltage, and Ground better? Why?
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2answers
54 views

How does the number of PCB layers affect the temperature of the board?

I understand that a PCB with the exact same circuit on a 2-layer board will get hotter than a higher number board: 4-,6-,8-layer boards. But, I have not been able to find the reasoning for this ...
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2answers
105 views

4 layers PCB VIA and power plane

I’m working on a 4 layer PCB and this is my stackup: 1-TOP (signal) 2-GND (plane) 15-VCC (3V3 plane) 16-BOTTOM (signal) On top layer I have a buck converter with 3V3 and GND output (0.5A max abs. ...
2
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1answer
129 views

Power rails routing question

I am currently designing a pretty big 4-layer development board 350mm x 270mm. Keeping in mind I have multiple analog digital and AC mains voltage, what would the best practice be regarding routing my ...
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1answer
74 views

Controlled Impedance Trace-reference plane Placement

I am new to high-speed PCB design. I was studying controlled impedance traces from the internet with the help of various documents. Everywhere it says controlled impedance traces need a reference ...
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2answers
201 views

Trace impedance for two signal layers between ground planes

When watching a few videos about stackup, EMI and impedance (especially this video from Fedevel Academy: https://youtu.be/52fxuRGifLU), I got confused how to compute trace impedance in the case of two ...
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3answers
501 views

4 Layer PCB Standard Stackup Grounding

I'm about to start placing components on my very first 4-Layer PCB (wrapping up schematic and MCU software tested on 2-layer pre-prototype, all runs surprisingly ok, but still 2 layer meh). I've ...
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2answers
213 views

4 layer stackup, inner layers GND & PWR

To "somewhat" quote Rick Hartley, "the energy isn't in the traces & planes but in between", I'm now wondering, when I use the following stackup: Sig GND PWR Sig You would ...
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1answer
126 views

Characteristic Impedance of Multi-Dielectric Coplanar Waveguide

Background I've calculated the characteristic impedance of a CoPlanar Wave Guide (CPWG) type transmission line on my 8-layer stack-up between L1 - top layer and L2 - GND1 directly underneath it. The ...
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1answer
51 views

Determine copper thicknesses for multi layer PCB

When deciding PCB stack-up generally accept the manufacturer suggestions. Especially they calculate the track impedance more accurate. For my last design I checked the guideliness for the FPGA (...
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2answers
174 views

PCB trace height to width ratio

I came across the Isola IsoStack website that lets me test PCB stack-up using Isola substrates: https://www.isola-group.com/isostack My project is using a stripline design with a 1oz copper inner ...
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2answers
260 views

Ethernet 1Gbps - PCB stackup

I am planning a stackup for 2x Ethernet phys. The chip requires a few different supply voltage levels: I/O Power 3V3 (3 pins) and Analog Supplies: VDD2V5 (2 pins) and VDD1V0 (4 pins). Each pin has ...
2
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3answers
2k views

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: https://cart.jlcpcb.com/...
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1answer
366 views

2 ground planes vs ground and power plane for 4-layer pcb with many power rails

I'm creating a 4-layer PCB design that takes a \$12\,\text{V}\$ DC input and converts it into 9 different voltages for various components on the PCB. I understand that a common stackup for 4-layer ...
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0answers
37 views

32F746GDISCO Stackup and Ethernet Impedance

I have an example board with PCB about the ethernet application. I noticed a mismatch between stack up and ethernet lines, or something else I don't know. Ethernet Lines are drawn with 0.125mm and its ...
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2answers
212 views

Chip antenna and PCB StackUp

I'm working on a ISM (868Mhz) weather station for my home and i'm trying to implement a Ceramic antenna directly on PCB. After reading the guidelines, i have questions again. One of then is what ...
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4answers
273 views

Question about proper PCB stack-up

I've got some question about stack-up for 4 layer PCB. My design is rather simple but due to many connections all arround PCB it couldn't be made with 2 layer PCB, this is why I picked 4 layer board. ...
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2answers
297 views

Why is the signal-power-signal-ground 4 layer PCB stack frowned upon?

Commonly, the best practice 4-layer PCB stack up is (from top to bottom) signal-ground-power-signal. That keeps the signal layers close to a reference plane, and ...
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2answers
411 views

PCB Stack up 4 layer Micro vias, Stacked Vias and Buried Vias

I am designing a 4 layer board in which I HAVE to use blind and buried vias. This is a very dense board with (SOLID COPPER ON LAYER 4, No exceptions ) I am planning to use 1.) 1-2 microvia and 2-3 ...
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3answers
1k views

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 ...
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3answers
2k views

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 ...
0
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1answer
149 views

Dual supply PCB layer stackup

My PCB is powered from USB port and includes Recom RKZ0505D for powering dual-supply OPAMPs. Recom gives +5V and -5V outputs. So I have: Top signal & components Bottom signal & components GND ...
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1answer
668 views

8-layer PCB stackup question

I'm designing a 8-layer PCB stack up. I have two choices as below: ...
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3answers
560 views

The distance of the adjacent signal layer in PCB stackup

I saw in some PCB stack-up design, sometimes there are two adjacent signal layers, such as: SIG GND SIG SIG PWR SIG I think there must some crosstalk between them, so how much should be enough ...
2
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1answer
273 views

Manufacturing PCBs for DDR3 memory

I'm currently designing a 4-layer PCB for a SOC (Allwinner A33 to be precise, 0.8mm-pitch BGA) with one DDR3 chip. Per DDR3 routing requirements, the traces need to have 50-ohm impedance. Also, they ...
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2answers
719 views

Altium Designer Rigid Flex - Placing Tracks Between Sections

I've done rigid-flex PCB designs a number of times in the past but it was long enough ago that I cannot remember how I solved this issue. My design has three sections - the main board, the flex, and a ...
6
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1answer
2k views

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 ...
0
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1answer
186 views

Routing of multiple impedance controlled tracks

I am designing a board with 50 and 75 ohm tracks on the same layer.My board receives SDI video via RG179 coax. The board has an SMA connector that receives the said input. The track is 75Ω track. ...
6
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3answers
2k views

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 ...
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2answers
151 views

PCB Layer stack up related query

I have seen many of the 4,6,8...layer stack up . Layer 2 prepared as solid GND plane for shorter return current path(reference plane. What is the reason for layer 2 is ground plane in most of the ...
3
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1answer
700 views

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 ...
5
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1answer
2k views

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 ...
3
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1answer
487 views

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. ...
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1answer
2k views

How to model PCB Trace with RLC?

I have a PCB board with the stackup shown below. I want to calculate what would be the impedance (and capacitance too?) of a 5" PCB trace on the L1 layer. How to ...
3
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2answers
1k views

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 ...
4
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2answers
1k views

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 ...
5
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1answer
509 views

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-...
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1answer
211 views

PCB stackup plane distance

What are the main reasons why one would choose one of the following options: sig (1") space gnd (4") space pwr (1") space sig comparing with sig (1") space gnd (1") space sig/pwr (1") space sig I ...
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1answer
468 views

PCB stackup for Mixed-Signal IC

I need to design high-density board with MCU, external RAM, GPS, GSM, Bluetooth, CAN, RGB interface on small size(5x10cm) and got into thinking which stackup should I use. Currently I have almost ...
0
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1answer
656 views

Is an edge coupled microstrip / stripline a differential pair or any two adjacent traces?

I got a suggested layer stack, and and it makes mention of "edge coupled offset stripline" and "edge coupled coated microstrip". Are edge coupled traces differential pair traces or are they any ...
3
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1answer
620 views

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 ...
2
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1answer
471 views

8-Layer Stackup question

Alright. I was given the task to design an analog design board which contains lots of opamps, some CMOS switches and some ADCs/DACs. It also contains 4 separate power supplies (each supplying +5V and -...
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1answer
4k views

PCIe add-in card thickness tolerance

I can't find a tolerance measurement for the 62 mils thickness specified in the PCIe electromechanical spec. How much leeway do I have for board thickness in an add-in card. Additional details: I'm ...
1
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1answer
303 views

Stack up question...return current when signal layers sandwitched between planes

I have stack up like this: My question is, when any signal layer is having GND plane on one side (above/below) and Signal Plane on other side (above/below). whether high speed return current will ...