Questions tagged [trace]

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

Filter by
Sorted by
Tagged with
47
votes
5answers
40k views

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 ...
44
votes
4answers
59k views

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 ...
25
votes
6answers
5k views

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?
16
votes
4answers
3k views

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 ...
15
votes
3answers
4k views

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 ...
14
votes
2answers
1k views

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. ...
13
votes
2answers
6k views

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 ...
11
votes
3answers
988 views

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 ...
11
votes
3answers
5k views

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 ...
10
votes
2answers
12k views

Trace width and clearance calculations

What is the math behind traces and clearance calculations? I am designing a PCB, which will carry 12V and 6A, what should be trace width and trace clearance? Similarly, what should it be for 12V 3A, ...
9
votes
3answers
11k views

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 ...
8
votes
4answers
2k views

Does the impedance of a PCB track matter if the length of the track is far smaller than the wavelength of the signal?

I have a PCB with tracks of no controlled impedance. The longest track is shorter than 1/5000 of a wavelength. Does the impedance of the track even matter? If not, then at what length would I need ...
8
votes
3answers
2k views

How to connect large traces to pads in PCB?

I am designing a PCB, and 10 A-15 A current is flowing in a trace. I think a 300 thou track should be used for 1 oz Cu-thickness. I see that it is impossible to connect two pads ...
8
votes
2answers
1k views

thickest pcb track before hitting ridiculousness in digital circuits

Ok, you can call me ridiculous. But, When I make PCB's, I learned myself to get into a habit into making thick PCB traces for every wire including those that others would use maybe a 5 - 8mil width. ...
8
votes
5answers
1k views

Best way to test a high current pcb design 70A @ 12V

I designed a circuit (MOSFET HBRIDGE) that Should Be able to handle 70A @ 14V. Now that the board is sent out I am on to thinking about how to properly test it. Right now the most logical way I have ...
7
votes
4answers
2k views

What is the name of a footprint that is designed to let you cut the trace between two nets?

I am designing a board where I want to have the ability to separate the connection between two power net's by cutting a trace. Originally headers were meant to be used but due to size constrains I ...
7
votes
3answers
945 views

Does this layout ever make sense to do?

Let's say I've got an power output and I want to power a chips Vin's with it. But, let's say it's a couple of different digital Vcc's on the chip that I want to power, like a rail for an LO, a rail ...
7
votes
4answers
24k views

How to calculate parasitic capacitance in a trace?

I am given the equation for parasitic-capacitance as: \$ C = \dfrac{\epsilon_r \cdot \epsilon_0 \cdot L \cdot W }{ d }\$ I am also told my trace is to be 1000 micrometers long (1mm) and 45nm wide. ...
7
votes
2answers
971 views

What should be considered when sizing trace widths for digital logic signals?

For traces that carry a static DC current, it's pretty easy to calculate the minimum trace width based on the required ampacity of the trace. However, I'm not sure what should be considered when ...
6
votes
3answers
18k views

What is a suitable temperature rise for PCB traces?

I'm designing a PCB for a 10A relay and am trying to determine what the trace width should be. According to this trace width calculator, the biggest factors in the width are copper thickness, ...
6
votes
1answer
158 views

What design limitations does a higher-than-average resistance trace impose?

There's a Kickstarter running right now for a machine that prints circuit boards. Rather than a traditional etching process, they use conductive (silver-based) ink to print traces and pads. It has a ...
6
votes
2answers
3k views

Altium 15 - Cannot see traces in 3D view

I am new to PCB designing and I've finished creating the my first prototype board. I want to send it to get printed but I'm worried that I haven't done my traces correctly because they do not show up ...
6
votes
2answers
1k views

Power Plane and Decoupling Capacitors Routing

Forgive me for my simplicity. I'm just a hobbyist and not an engineer by trade. I am trying to make my first 4 layer PCB in Eagle and I have a question I cannot find the answer to regarding power ...
6
votes
1answer
412 views

Things to be aware of when using voronoi shaped traces

I was thinking of giving voronoi shaped traces (e.g. http://publications.csail.mit.edu/abstracts/abstracts05/rus/rus.html for those who need an example, or just google image search it) a try. In ...
5
votes
1answer
1k views

Can a ground plane be used as a current return path? (DC only, no signals, no AC)

I'm creating an adapter which hosts two connector types and simply routes two connections from one connector into the other. Only two traces/connections are used; Vcc (about 6v) and GND Operating ...
5
votes
2answers
718 views

Satisfactory Margin for Traces from PCB Edge

I've had problems routing too close to the edge of a PCB before and was wondering if there's a suitable rule-of-thumb that I should use (maybe to put in a design rule in Altium somehow with my keepout)...
5
votes
2answers
1k views

LM13700 Question

I'm currently troubleshooting a state-variable filter I built. All of the filter types work, but the resonance pot has no effect. Tracing a sine signal through the feedback pathway, I found that it ...
5
votes
1answer
3k views

PCB trace clearance in 220V circuit

This is a pcb layout where I am converting 220V rms to a DC voltage (for microcontroller). The pcb has severe size constraints. This is one design I could come up with: Circuit explanation: Consider ...
5
votes
3answers
4k views

Meandering traces necessary for 24-Bit parallel RGB LCD interface?

I am working on a project that interfaces an Atmel SAMA5D3 MCU with a LCD TFT display. The interface between both is 24-Bit parallel RGB with HSYNC and VSYNC signals. The resolution of the display is ...
5
votes
2answers
7k views

How does Altium Designer's “impedance constraint” feature work?

Altium has a design rules option for setting a track width constraint according to line's impedance (e.g.; 50\$\Omega\$). How do I use it? Please give me instructions or a link to an online tutorial. ...
5
votes
1answer
2k views

Does my PCB Require 50 Ohm Impedance trace even if i am using external antenna?

I am using the Quectel M95 GPRS Modem in my PCB, and the hardware reference guide says "The Pin 39 is the RF antenna pad. The RF interface has an impedance of 50Ω. " I am using a u.efl connector and ...
5
votes
1answer
922 views

Trace width to 0805 pad?

How worried should I be if I route wider than 10 mil trace to 0805 pad? Would 16, 20 or 24 mil trace cause soldering problems without making 10 mil neck?
5
votes
1answer
424 views

Routing large RF trace to small SMD pad

I am designing an RF board in Altium where due to the dielectric selected and its thickness, the trace width for a 50 ohm characteristic impedance is thicker than some of the SMD component pads. What ...
5
votes
2answers
7k views

Design rf trace antenna 433MHz + 315MHz on pcb

I'm a hobbyist and I'm designing a PCB in Eagle that include micro controller and RF receiver and transmitter, 2 modules of 433mhz and 2 of 315mhz, I have a defined place on the PCB of 10x50 mm for ...
5
votes
1answer
3k views

How to route a trace on PCB with 50 Ohm impedance?

I used some online calculator to calculate parameters of trace so it has 50 Ohm impedance. I use FR-4, so H=1.5mm, T=0.035mm and Er = 4.5. 2-side PCB, one side with signals, the other with GND. I set ...
4
votes
3answers
3k views

Can I prevent copper traces from delaminating due to soldering heat?

I'm making a PCB that has a 100pin QFP pacakge microcontroller. After gaining experience with the UV photoresist process and reliably making the small, 0.5mm traces, I have a new problem: the copper ...
4
votes
2answers
3k views

What types of signals should be considered to have a 50 Ω trace impedance?

Generally speaking, what time of signals should be designed to have a 50 Ω trace impedance ? Some datasheets I've read have specifically mentioned 50 Ω but others have not. Is it good practice to ...
4
votes
1answer
3k views

Formula for voltage drop vs PCB trace width, temperature, current, and trace length

I need to find out the voltage drop in the PCB traces with respect to the possible factors like: copper thickness, trace length, trace width, temperature, etc. I found some calculators available at: ...
4
votes
2answers
2k views

Why Altium routes trace to the side of the pad?

I am curious, are there any reasons why Altium tends to route a trace to the side of a pad, instead of the top? The top looks more logical, since it will not disturb other traces in a SOIC for example....
4
votes
3answers
4k views

How to measure propagation velocity through a trace on a pcb?

With a pcb in hand, how to measure the propagation velocity of a path from point A to point B, with accuracy in the picoseconds range?
4
votes
2answers
391 views

Routing thick high current traces to small SMD pads?

What is the best practice for routing high current traces through the pads of small 0603 components? I have a wide high current trace which that passes through a 0603 decoupling capacitor. Initially ...
4
votes
1answer
408 views

Why break a PCB trace plane into multiple parallel traces?

I have a vehicle battery maintainer (20A) that was overloaded and stopped working. On inspection I found a group of traces blown, however all the traces are connected at both ends. It looks like a ...
4
votes
3answers
196 views

Good method to remove tenting on vias after assembly for debugging?

This is a question about modifying an assembled board to make it easier to debug. In a perfect world, I would have left the bottoms of these vias un-tented. Whoops. I have two BGA parts on a PCB, ...
4
votes
2answers
3k views

adjacent trace capacitance (horizontal)

I find a lot of online tools to calculate the capacitance between two traces (or a trace and a plane) on opposite pcb layers. One such tool can be found here: http://chemandy.com/calculators/...
4
votes
1answer
1k views

How does trace/via clearance affect parasitic inductance if they go to the same net

After reading [Mike DeSimone]'s response regarding good decoupling and bypassing practices I kept wondering about distance between wires (wire = trace or net) . [Mike DeSimone] comments that wires ...
4
votes
2answers
455 views

What's the point of this thick trace in my PCB?

I'm looking at a trace that goes from Pad 2 of a component to pin 22 of the QFN. What's the point of the thick trace at the beginning if it ends up being as small the pin where it is run?
4
votes
1answer
3k views

Are there any rules of thumb when computing pulse current ratings for PCB traces?

Say I have a surface PCB trace, 4 oz, 50 mils. That trace should be able to carry around 15 amps continuous, according a calculator I'm using. (Obviously your trace ampacity estimates may vary with ...
3
votes
3answers
1k views

50 Ohm Single Ended Signal Impedances on PCBs

I have a basic understanding of transmission line theory and how 50ohm traces are designed on a PCB. I was wondering what the origin of this 50ohm impedance is. Are single ended digital signals on ICs ...
3
votes
4answers
582 views

Beyond what is recommended by fabricators, how far should traces be from SMD pads?

Having followed a fabricator's DRC (this case being OSHPark), this distance between an SMD pad and a trace is considered acceptable (see attached images). However, I wanted to inquire about what the ...
3
votes
1answer
532 views

Long lines: whether or not to treat PCB traces as RF lines

My setup: 53 x 28 mm PCB, uC will run somewhere between 1 MHz and 8MHz. Dual layer PCB design. From the info I gathered on this site it seems there are two aspects to consider in deciding how to ...