2 layer pcb ground plane

Latest Projects Education. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Thread starter miguelon Start date Jun 1, Search Forums New Posts. Thread Starter miguelon Joined May 20, Hi all, this is my first post in this forum, but I've read a long time.

Very helpful for newbies like me in the matter. So thanks to the people who make this possible. I'm designing a PCB with smd components on a 2-layers board. Nearly all components are in the top layer and some components are throu hole like the pin header to support a LCD, etc. The bottom layer has some lines that are imposible to route on the top layer so I use them to route this lines. The rest of the bottom layer is for the GND plane.

The top layer have a lot of components that need a 3.

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I use the poligon tool in Cadsoft Eagle to fill all the spaces left by the components in the top layer. I don't know if this way is erroneous or not. Thanks in advance. Sorry for the mistakes in english. Greetings from Spain. Scroll to continue with content.

VCC & GND planes in a 2-Layer Board

A flooded plane on the top layer between the components and traces is a common way to get a low impedance ground or power connection. You just have to make sure that all the segments of the top plane are connected together and not separated by a trace. On a switching regulator board I did I used the top plane for the ground so that the surface mount decoupling capacitors could go directly from the power pins on the top components to the ground plane. Thus there were no vias in series with the capacitors, which would otherwise add resistance and inductance, increasing the decoupling capacitor's impedance.

MrChips Joined Oct 2, 21, Looks ok to me. Besides the composite view both top and bottom show us two more views with top layer only and bottom layer only. Show us layouts x2 or x4 enlargement. The PCB manufacturer actually likes planes on both sides since that means they have less copper to remove in the etching process.Back when I was a young and hungry grad student, my first PCB ground plane design was used to collect analog signals from several sensors.

When looking at a voltage graph of my measurements, the noise level was horrible and completely masked the signal I was trying to measure.

2 layer pcb ground plane

I soon realized that I had completely bungled my ground plane connections, and ground loops were ruining my signals. Placing your ground plane and routing to ground are two of the most important design guidelines in PCBs with two or more layers.

Doing this correctly can help reduce susceptibility to EMI, suppress crosstalk, and prevent ground loops. These noise sources degrade signal integrity, and proper circuit board ground plane design techniques will ensure that your device shows maximum performance. If you're new to PCB design, your first PCB will likely to be a two-layer board as they are relatively simple to work with from a layout and signal integrity perspective.

This is the first point to consider when determining whether to include a ground plane and where to place it on the board. Using a 2 layer PCB ground plane is also preferable to just routing ground traces. Placing a ground return as close as possible to a signal line allows the return signal to closely follow the trace, which minimizes loop inductance and EMI susceptibility. Nearly every board that includes multiple components will simply not have enough room for routing return traces alongside all signal traces.

Placing a ground plane on the bottom layer of a two-layer PCB provides the same effect; placing the ground plane below signal traces also reduces the loop area seen by signals. Ideally, signal traces should be placed as close as possible to the ground plane to suppress crosstalk between neighboring traces, which might require using a thinner board. Placing a ground plane below the relevant components and signal traces also allows you to route ground returns directly from a component to the ground plane through a via.

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The return signal will then follow the path of least impedance back to the power supply return. Prevent EMI with proper routing and grounding techniques. Rather than place a continuous ground plane across the entire bottom layer, one technique that can be used in a two-layer PCB is gridding.

Power and ground traces are routed in a differential manner, mimicking a pair of power lines. Every ground trace can be expanded to fill up as much of the empty PCB space as possible, and all the remaining empty space can be filled with ground pour.

This technique will give your 2 layer board the same level of noise reduction as a four-layer PBC stackup. One other solution is to use two perpendicular grid patterns on both layers, and the grids can be connected with vias at points where the grids cross. This ensures that all sections of the grid remain at nearly the same potential and provides some extra real estate for components on both layers. A potential problem with this design is with routing between grids on a single layer.

In this case, a grounded trace can be routed next to a signal trace, where the grounded trace is connected to the ground sections on the opposite layer with vias. As with many design choices, gridding represents a tradeoff: you get more real estate on your board and can create low inductance current loops with creative routing, but you lose some of the EMI protection provided by a continuous ground plane. The vias required for gridding also act as inductive impedance discontinuities, creating signal integrity problems with high speed signals.

Gridding can also form a conductive loop around components, and radiated EMI can induce current in this loop of conductor. A better choice is to place components on one layer above the ground grid on the other layer. To summarize, be careful with gridding. Certain design guidelines will recommend gridding in a two layer board as an alternative to using a continuous ground plane on a single layer. The best practice is to separate the ground plane on the back layer into a digital section and an analog section, but leave the two planes connected near the return to the power supply.

This ensures that digital signals do not follow a return path beneath sensitive analog components. The ground plane for a mixed-signal two layer PCB can have a notch that separates different sections, although routing traces over a notch will create a very large return path for the return signals in the ground plane and is not recommended.

These traces will radiate strongly and the circuit will have large loop inductance, leading to higher susceptibility to radiated EMI. It is a bad idea to completely split a ground plane and try to bring the sections to the same potential using something like a ferrite beadas this creates more EMI and noise problems than it solves.

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It only takes a minute to sign up. All components are through hole, the PCB is pretty large about 16cm x 10cm and has 2 layers. Plated through hole are supported by the technology I am using. The circuit has a dual supply. Which and why of the following is the best solution for routing signals, power supply tracks and ground?

I think all these other answers are over-complicating the issue. Through-hole designs are legitimate in many cases, and so are 2 layer boards. This design method is tried and true and I don't see any reason you shouldn't use it. I think it doesn't really matter which side you put the signals on. You will need to make some jumpers in the ground plane, but this won't cause any problems if you avoid making large cuts. I made a quick and terrible image in paint to illustrate:.

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As Neil mentioned, your ground return paths do matter, you shouldn't just consider them finished when they enter the ground plane. Generally, any arbitrary division of spaces into power, ground, signals, is going to give you some grief, because it's neither necessary to partition them like that, nor sufficient to get a good result.

But that's not sufficient, you need to know where the return currents are flowing in it, because you can still shoot yourself in the foot, even with a ground plane. The great benefit of Manhattan is it means you can always find a route for your track.

You never have to compromise and take a signal a meandering route away from its return path, or cut a ground plane to sneak a track through, destroying its integrity. Manhattan routing involves dedicating one layer for North-South connections, and the other layer for East-West connections.

Now you can always get from A to B with typically one via, and you never have to wonder about how you can cross a track. Now you have a systemic way to route your board, start with a gridded ground. On one layer, put a track every 20mm or so, in columns. On the other layer, do the same in rows. Via them together at every intersection. Now you have a ground that is very nearly as good as a plane, and far more useable, because both layers are still available to route all your power and signals.

Move the ground tracks around a bit to accomodate your ICs by all means, but don't move them too far apart. I've had some interesting comments from Umberto, Scott, and Olin, which suggest I haven't quite got my point across. I'll perhaps clarify what's above, while documenting my reasoning below. I'm now retired, and after a lifetime mentoring junior engineers, one of the biggest problems they face is doing a poor design on a ground plane board.

They seem to think that the ground plane 'will take care of all that isolation stuff', and they stop thinking. As a result, they run high currents past sensitive inputs, and otherwise fail to spot the effects of return currents. In order to help them debug these boards, I remove the ground plane, and force them to consider all return currents as discrete flows in separate tracks. Once the culprit has been found, and the layout fixed, the ground can be restored.

On a 4 layer board, there's enough space to dedicate one to a solid ground.Somewhere I read that it is best on a two layer board to keep the power traces the same size as the data traces. Another other "wives tale," Which I started using when I did a Video board, Is to not let any part of the ground plane loop back onto itself.

Or form rings around components. Rather to create the grounds as sections and connect them by a single small trace. Again this makes a difference, which I was able to measure. The reason for this, is that the current travels on the outside of the wire.

Like cars in heavy traffic or sand in an hour glass. A plane that rings around something is actually a coil in an inductor. Then there is the parasitic capacitance if the trace is too wide, add in the the natural resistance and you have some unintended filters and RF transmitters That attract noise. Back in the 70s they made everything wavy, like it was hand drawn, because there was some sort of rule about 90 degree bends being more noisy. Personally I think the angled bends just look better and you can fit more traces in.

I see no problem in doing that, but my question is how will you route the rest of the traces if your only 2 layers are filled with power? It's best to have as continuous a ground plane as possible and anything else routed on the other side of the board.

Quote: it is best on a two layer board to keep the power traces the same size as the data traces. But not for power! In my experience: - Make both sides ground planes before routing. Route everything, then as the last thing flood the ground copper and optimise the planes with through-holes and by moving traces to get fever "naked" spots on the given layer.

Drawing a lot of current at high frequencies through a long, thin trace is just asking for trouble. Making the Vcc and ground lines as short and fat as possible makes them less coil-like. This is especially important where a powerpin supplies a bus port on a processor or similar device. If all pins switch from high to low in a very short time, the inductance of the trace supplying the powerpin suddenly becomes critical. Leads, PCB-footprints and traces of decoupling condensers typically contribute from pH if done right to 4nH if done wrong, and worse is definately possible.

I can recommend nF polyester capacitors placed as close to the pin in question as physically possible. Placement of the electrolytic capacitors is less vital, since they decouple spikes of much lower frequency.

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Parasitic capacitance between signals and ground should only be of significance if you run at very high frequencies or have very long traces, and this may be countered by specifying to your program that plane copper keep a distance of, for example, 20mils. Place sub-groups of components optimally in relation to each other outside the board first, and then place each "module" afterwards, while looking at the unroutes to make sure you won't have to do a lot of criss-crossing later when routing.

It may cause more vias, but it makes it easier to route and optimise and makes for more coherent planes afterwards. I often use copper pour on single-sided boards to save having to route ground connections and to help give a low-impedance ground.

Quote: Do not let any part of the ground plane loop back onto itself. Well, that was one of my concerns.Ensuring that an electrical device functions properly is great and all, but the first priority for any electronic is being able to turn it on safely.

It reminded me of the absolute importance that power planes maintain for PCB design. Without power, the components on your PCB might as well be inert pieces of metal.

In order to light a lightbulb, spin a motor, or otherwise perform some action such as maintaining the optimum temperature on your DIY espresso machine, your board needs a steady supply of voltage to function.

Similar to how the ground plane is connected to the ground connection of the power supply. Its purpose is to provide a steady supply of voltage to your board. Whenever a component needs to draw power, simply run a trace to a via that makes contact with the power plane and completes your circuit. This is because the best practice for multi-layer stackups are to use an even number of layers.

The popular 2 layer board will generally benefit more from a ground plane instead of a power plane, relying on tracks to deliver power from a power source.

Power planes come with a number of advantages over tracks and traces when they can be used in a PCB design:. Improved decoupling between circuits. The surface of a power plane can create a parallel plate decoupling capacitor between itself the insulating layer and the following ground plane that prevents noise from propagating through the power supply from one circuit to another. Shorter return paths.

The convenience of following a via down from a signal layer to the power plane to power a circuit. Shorter return paths lead to better EMC performance. Larger current carrying capacity. Power planes can handle more current than traces or tracks, lowering the operating temperature of your board.

Having a single well of power for all the components on a signal layer to draw from makes a lot of sense if they all have the same voltage requirements. Increasingly, however, more complex high density PCB designs have made the practice of splitting a power plane into multiple domains more popular.

In such situations, you will usually still have a ground plane to allow for shorter return paths and noise absorption. Aircraft voltage regulators can be necessary in sensitive aerospace designs. Furthermore, having layout software that can have cross-team collaboration as well as encourage easier analysis and simulation of your designs will ensure proper power plane management. EDA software greatly simplifies the process of designing, simulating, and testing your PCB designs for electrical, thermal, and physical performance considerations.

Cadence Allegro can certainly work with you and your team to accomplish any tough circuit design. Cadence PCB solutions is a complete front to back design tool to enable fast and efficient product creation.

Cadence enables users accurately shorten design cycles to hand off to manufacturing through modern, IPC industry standard. As PCB technology increases to accommodate the needs of high speed design signal integrity, you need to carBuilding upon a firm foundation is a staple of literature, poetry, and parables.

Without a firm foundation, whatever is built on that foundation will be subject to failure. This applies equally well for construction concepts, career and education, relationships, and even mental health.

It pays to lay a solid foundation in whatever it is that we are building. Printed circuit boards certainly have a foundation in their board materials and how those materials are configured in the layer stackup. Another foundation that is equally important however to the PCB is its ground plane. Without careful attention to the ground plane the board may not perform as intended, and it may be subjected to all manner of electrical noise and interference.

The ground plane on a printed circuit board is typically a large area of metal connected to the circuit ground. This area of metal is sometimes only a small portion of the board, or in a multi-layer design it may be one entire board layer. Depending on the needs of the design, it may even occupy multiple layers. Voltage return : Most every component on the PCB will connect to a power net, and then the return voltage will come back through the ground net.

On boards with only one or two layers, ground nets usually have to be routed using wider traces. By devoting an entire layer to the ground plane in a multi-layer board however, it simplifies connecting each component to the ground net.

2 layer pcb ground plane

Signal return : Regular signals also need to return, and with high speed designs it is very important that they have a clear return path on the ground plane. Without this clear return path these signals can generate a lot of interference for the rest of the PCB. Reduce noise and interference : As signal speeds increase, there are more digital circuits switching states.

This creates noise pulses through the ground circuit that may affect other parts of the circuit. A ground plane with its large conducting area helps reduce the amount of this disturbance because it has a lower impedance than if the ground net is routed through a trace.

By carefully planning out the layer stackup configuration of a multi-layer circuit board, the PCB designer can use ground planes to help control the electrical performance of the board. By using a ground plane between two active signal layers, the crosstalk between the signals on those layers can be eliminated. And by making sure that there is an uninterrupted signal return path on the ground plane, the signal integrity of high speed transmission lines can be improved.

Ground planes are also often connected to components that get hot in order to help dissipate the heat. Examples of thermal relief pads in a small ground plane. As we said, a ground plane can either be a designated area of metal on a circuit board layer, or it could take up the entire layer itself. Most CAD systems give you the ability to draw a plane so that it appears as a solid patch of metal, and you can designate any net for a plane whether it is ground, power, or something different.

CAD systems used to use negative image planes, as that took less computing power, but most PCB designers prefer drawing positive planes today as the tools now have plenty of power for this.

The PCB designer will draw the area for the power or ground plane on the designated layer in the shape that they desire. On an inner layer of the board this is usually the entire layer, while on the exterior layers of the board it is often smaller areas to service specific components or group of components.

2-layer PCB ground plane advice

In some cases the designer may split the plane on an inner layer. This can prove to be very useful when cutting back on how many layers the board will be made with. Usually a plane split is done for power nets however, while the ground plane remains a full layer to help improve signal integrity and eliminate noise and interference. When the plane is drawn by the PCB designer, the CAD tools will automatically create a connection for the component pins that are within the contours of the plane.

This connection is either a thermal relief, or a direct connection flood. Thermal reliefs are small voids in the plane around the perimeter of hole used for a thru-hole pin. Without a thermal relief, the thru-hole pin would be directly connected to the plane which would act as a huge heat sink making soldering difficult. With the relief however, the part can be soldered and unsoldered much easier.

All other holes, such as vias, will normally have a direct connection to the plane. The key to creating a good ground plane in your PCB design is to put the tools to work for you.

2 layer pcb ground plane

Make sure that you go through and set up all of your design rules and constraints before you start working with plane layers. Most PCB design CAD systems will allow you to set up different connection parameters depending on the net, and the layer where the connection will be made.This meant that they were usually six layer multi-layer boards, with a ground plane and a VCC plane.

Thankfully this all changed long ago. Now instead of being driven by the limitations of those older CAD systems, you can drive the design tools to create the plane layers the way you want them to be. You have the choice of creating a ground plane that is either a positive copper fill, or a negative plane depending on what your needs are.

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Any CAD system can do this, but some are better at it than others. Take Altium Designer for example. This PCB design system does a great job of enabling you to create the planes that you need. Let me show you how. Before you create your ground or voltage planes in layout, you will want to make sure that your schematic is set up correctly. This means that you have assigned the right net names so that all of your power and reference planes can be created correctly in layout.

Naming Schematic Nets in Altium Designer. The advantage of the power port is that it will connect across all sheets of your schematic without having to attach an offsheet connector to a named net. Once your nets are correctly named, you are ready to synchronize your schematic and layout to begin working with your power and ground planes.

2 layer pcb ground plane

The first thing to do when creating an internal plane is to add a design layer specifically for the plane. The next thing to do is to assign the correct size for the thermal relief pads and clearances that you want on your plane layers. As you can see in the picture below, you have the ability to specify the expansion, air-gap, and conductor width of a thermal relief pad.

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You can also specify the type of connection you want. In the example below you can see how the pad connection is set for a thermal relief while the via connection is set as a direct solid connection to the plane. Setting up thermal relief pads in the design rules of Altium Designer.

The menu above also gives you the ability to set other values for your planes. Note on the left side of the picture that in addition to the plane connection style, there are also categories for plane clearances and polygon connect styles.


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