Questions tagged [trace]

Lanes of copper on a printed circuit board, for carrying current or signals between pads

Traces are long, thin lanes of copper on a printed circuit board (PCB). Traces typically connect two pads on the PCB, creating a conductive path between them. Like any conductors, traces exhibit resistance, inductance, and capacitance, and all these factors may matter when laying out a PCB. Perhaps most notably, the width and thickness of a trace determines its current-carrying capability.

Trace width is often spec'd in mils (thousandths of an inch), and trace thickness is often spec'd in ounces of copper per square foot.

Traces are typically distinct from copper planes, pours, areas, or polygons.

Traces typically do not connect at right angles to other traces.

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How can PCB trace have 50 ohm impedance regardless of length and signal frequency?

Hmm, this seems to be just another question on line impedances. I understand that when we say "transmission line" effects we talk about things like cross talk, reflections and ringing (I guess that is just about it). These effects are not present at…
quantum231
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How to make traces on an universal PCB?

I hope this question won't be closed as too subjective. I'd like to know best practice - how to make traces on universal PCB's with individual holes without traces (like the following image). My idea is to bend the ends of discrete components and…
Al Kepp
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Is it OK to route a trace through a pad?

Will I have any trouble routing the traces in this way? (VCC and GND) Is it OK considering that the entire circuit current is under 50mA?
Lucas Alexandre
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In PCBs, why is copper etched away instead of added?

I know that in virtually every case, PCBs start as a substrate with a layer of copper laminated on top, which is then etched away, leaving the traces. But why are the traces not added on an empty substrate instead? I am well aware that the etching…
David Cian
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Breakaway PCB Design

I am aiming for a breakaway PCB design for a small series where an unneeded compartment can be broken off. (See Image below) I saw this for example on the STM32 Nucleo boards, where it is used to take off the flash interface once you're done with…
mxcd
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When laying out circuit board traces, what impedances do I need to consider?

I do low-speed circuit design for microcontrollers and such (usually at less than 20 MHz), and now I'm getting started on some more high-speed circuits. What I want to know is: What considerations need to be made for traces in high-speed…
machinaut
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Routing traces to and from a 48 pin microcontroller becoming a mess

I have a 48 pin microcontroller with VCC = 5V. I'm becoming worried that I have the traces too close and all the vias and crossing traces may mess with the signals' integrity. Are there examples and general guidelines to routing traces in such a…
Erv
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How far can mains voltage arc in air?

I wondered this while soldering a mains voltage circuit board and was surprised by how close together the traces were. It has obvious implications in design of electrical plugs, and the proximity of wires when doing anything to do with mains…
M_M
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Why do they make traces to LTZ1000 in spiral shape?

I was browsing Google images of LTZ1000 voltage reference IC. I saw that in some of the PCBs, the traces that go to LTZ1000 are in spiral shape and cut out gaps are left between them. What is the reason behind this?
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Is it proper to use an internal layer as a heat bed if I want to warm my multilayer PCB?

I need to design a circuit to warm my PCB. There are many ways to build up such circuit. But I learned from a post "Warming PCB in a low temperature environment" that maybe I can use traces as heater. My first idea is to use one of the internal…
billyzhao
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what is the current limit through a trace?

Similar questions and topics have been asked before such as Standard PCB trace widths? Formula for voltage drop vs PCB trace width, temperature, current, and trace length I've used PCB Toolkit in the past and I haven't had practical issues, but I…
efox29
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Is there any disadvantage to changing trace width in the middle of a trace?

Say I have a trace running across a board. It's 50 mils the majority of its length, but in one short place it narrows to 25 mils to make it through a tight area. As best I can tell, this will be preferable to a 25 mil trace the same length, and only…
Stephen Collings
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Trace impedance ohm meaning

I've been trying to understand the principle of trace impedance (single ended and differential) for a while, read several articles (all the best google has to offer), but I have still some serious issues finalizing my understanding of it. First of…
Ilya
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Can I solder a wire between two leads on a PCB to make up for a trace that isn't wide enough?

I have a PCB that has 2 traces on one corner who's width only supports a ~10a load. I need support for a 20a load. Actually, it really only needs to support a 15amp load but I'm trying to build in some healthy breathing room. Can I just solder a…
visionviper
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Connecting pads with the same functionality belonging to one chip

I have a question about routing style of pads with the same functionality belonging to one chip. I draw a picture in Paint (fictional IC; let it be the SOIC8 footprint). GND is only as example (it can be any net, but the same functionality for both…
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