Questions tagged [pcb]

PCB is the acronym to Printed Circuit Board. A PCB is a carrier for the circuit's components and their electrical connections.

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249 votes
9 answers

Decoupling caps, PCB layout

I guess I've been somewhat ignorant when it comes to the finer details of pcb layout. Lately I've read a couple of books that try their best to lead me on the straight and narrow. Here is a couple of ...
morten's user avatar
  • 4,653
125 votes
10 answers

Are solder fumes bad for me?

I do a fair bit of soldering (lead-free). Is breathing in solder/flux/paste fumes actually going to harm me? Are cheap fume extractors worth buying?
Toby Jaffey's user avatar
  • 28.8k
114 votes
8 answers

Best One-Off DIY PCB Creation Technique

I have finally built up a lab to design electronics in. I have quite a few designs I would like to test. I have tried the printer toner/iron technique a few times but have found that I cannot create ...
88 votes
6 answers

Looking for circuit board material that can be dissolved

We are working on a product where the entire device needs to be dissolved in liquid after the device has operated and the device is no longer usable or desired. This is a down-hole application. The ...
Dwayne Reid's user avatar
  • 23.6k
81 votes
11 answers

Why is there such a strong preference for 45 degree angles in PCB routing?

I've always wondered this: every single modern PCB is routed at 45 degree angle increments. Why does the industry prefer this so much? Doesn't any-angle routing offer more flexibility? One plausible ...
Roman Starkov's user avatar
80 votes
3 answers

Why are circuitboards traditionally green?

Green is the most common circuit-board color because it has become an industry standard. What I'm interested in is How the traditional "PCB Green" become a standard in the first place? Were there ...
Connor Wolf's user avatar
  • 32.1k
77 votes
13 answers

How to connect USB Connector shield?

How should I route USB Connector shield on PCB? Should it be connected to GND plane right where USB is placed, or should the shield be isolated from GND, or should it be connected to ground through ...
Andrzej H's user avatar
  • 975
72 votes
6 answers

What is Copper Thieving and why use it?

On many boards I've seen, there are little copper dots used for the purpose of "Copper Thieving". They're small round copper dots connected to nothing and arranged in an array. Supposedly they're for ...
Gustavo Litovsky's user avatar
68 votes
4 answers

What kind of glue should I use for PCB-mounted components to avoid vibrations?

I want to protect the PCB-mounted components from vibrations. What kind of glue/substance should I use? What are the most prone to failure components due to vibrations?
m.Alin's user avatar
  • 10.7k
66 votes
4 answers

What do the PCB markings mean?

On a printed circuit board, I see lots of tiny letters and numbers. Is there some kind of standard that dictates what letter indicates what type of component?
kinokijuf's user avatar
  • 906
65 votes
17 answers

How do you cut PCB?

I just spent about 20 minutes trying to cut through a PCB with a hacksaw. These things are really tough. What is the correct tool to cut PCB material, and get a nice straight line? I saw something ...
littlebirdceo's user avatar
64 votes
3 answers

How do I identify SMD components? (or how do I identify any component)

How do I identify the markings on an SMT component and match it up with a part number so I can be a good designer and actually look at a datasheet (and read the whole thing)? Or identify a part to ...
Voltage Spike's user avatar
  • 78.1k
62 votes
7 answers

Why are there teardrops on PCB pads?

What's the use of the teardrop shapes around some PCB pads?
Federico Russo's user avatar
57 votes
5 answers

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 ...
quantum231's user avatar
  • 11.6k
55 votes
7 answers

What is the usage of Zero Ohm & MiliOhm Resistor?

I am new to PCB design and I noticed that some schematics use 0Ω or 100mΩ resistors. What is their purpose and why do we need to use them in our PCB design? Normally if we wish to probe how much ...
Dennis's user avatar
  • 1,401
54 votes
14 answers

Solid ground-plane vs hatched ground-plane

Recently while routing a PCB, I came across the option to fill/pour my ground plane with either solid or hatched copper. I've also noticed that the old Arduino Duemilanove also had a hatched ground ...
Vikram's user avatar
  • 713
53 votes
6 answers

Standard PCB trace widths?

Is there a standard for the sizes of PCB traces? That is are some 25 mil and others 10 mil or is can you choose your own? I plan to run 400mA through some thicker traces, but less than 30mA for all ...
Thomas O's user avatar
  • 31.7k
52 votes
7 answers

The best stack-up possible with a four-layer PCB?

I'm designing a 4 layer PCB and I know that the standard stack-up is Signals GND VCC Signals (GND and VCC can be switched depending on the layer with more signals) The problem is, I don't really ...
mux's user avatar
  • 1,876
52 votes
4 answers

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 ...
Al Kepp's user avatar
  • 2,981
51 votes
2 answers

Competing PCB Crystal layout recommendations

This is related to this question: How's my crystal oscillator layout? I'm trying to layout a 12MHz crystal for a micro controller. I've been reading through several recommendations specifically for ...
helloworld922's user avatar
49 votes
3 answers

Why are vias placed this way on a PCB?

I used to check complex commercial PCBs specially those of graphics cards to see how professional PCB designers do their layout and learn from their techniques. When I checked the card shown below I ...
Abdella's user avatar
  • 2,605
47 votes
8 answers

Can we build capacitors on a PCB board?

For the magnitude of nF or µF capacitors, I hope I can build them on a PCB board. The capacitor is like a two metal layer and something between them. Is this possible? Not buying the capacitor, ...
alan's user avatar
  • 797
47 votes
3 answers

Why does an antenna trace have this shape?

I'm wondering why an antenna has a board trace that follows a certain "squiggly" shape. This doesn't have to apply to only antennas; I'm sure that there are other components that have changing paths ...
Ci3's user avatar
  • 815
45 votes
9 answers

Vias directly on SMD pads?

I was looking at an example board schematic provided by TI and I noticed something rather curious: vias were placed directly on SMD pads. Is this a normal/acceptable practice to follow, or is it ...
helloworld922's user avatar
44 votes
15 answers

What are low cost circuit and PCB design software? [closed]

Do you know of any freeware or low cost circuit / PCB design software? I know a few which I have listed below but I was wondering if there were more of its kind. Please mention the good features and ...
Edward's user avatar
  • 1,339
44 votes
3 answers

What are the advantages of having two ground pours?

I've seen many 2-layer PCBs that have a ground pour on both the top and bottom layers, I was wondering why do that ? and wouldn't it be better to use the top layer for power and signals and the bottom ...
mux's user avatar
  • 1,876
43 votes
2 answers

Why wiggle nearby tracks on a PCB?

I've been reading an article (TheMagPi eMagazine) relating to the Raspberry Pi; "An ARM GNU/Linux box for $25." In the article, page 17 at the bottom it shows an area on the Pi where a track zigzags ...
George Duckett's user avatar
43 votes
3 answers

What's radiating on my PCB?

I recently did a proper EMC test on a PCB of mine. It failed the test, and seems to be radiating in the 300MHz - 1GHz region, with peaks every 50MHz, and little peaks on the 25MHz. Looking at the ...
Rocketmagnet's user avatar
  • 27.2k
41 votes
10 answers

Do dead weight 'components' exist?

After making a prototype circuit board, I usually glue four rubber pads/bumpers to the bottom, to keep it stable on my desk: Unfortunately, my boards are usually too light. When connected to a few ...
K.Mulier's user avatar
  • 2,329
41 votes
2 answers

What did the manufacturer mean by asking if an angle should be made for the fingers?

I sent in Gerber files designed by someone else to PCBWay. It's a cartridge for a Commodore 64. They responded today with this question, and I'm not 100% sure what they are asking. Ref attached ...
Oggie's user avatar
  • 523
40 votes
2 answers

What is the purpose of those star like solder joints?

I recently watched a Xbox Series X PSU repair video on YouTube and was surprised by the fact some solder joints have a star-like shape: Is there any specific reason to do this? This is the first time ...
tigrou's user avatar
  • 1,873
39 votes
7 answers

How do I make sure my electronics design is good from manufacturing perspective? [closed]

I am a beginner in electronics design. I have some experience with fairly complex PCB design. I want to design a product that will hopefully sell a lot. How do I ensure that the design is inexpensive ...
superczan's user avatar
  • 491
39 votes
5 answers

What's the simplest Linux capable board I could make at home?

I'd like to make a single board computer capable of booting Linux, with my low-tech garage tools (2 sided PCBs, reflow skillet, no plating through holes). What's the simplest hardware design I could ...
Toby Jaffey's user avatar
  • 28.8k
38 votes
5 answers

Why does a commercial PCB need this much rework?

I found a PCB that has had some rework done. When I saw it, I thought that someone had actually repaired it after purchase:- It's got additional wiring (white & brown) and under the hot glue are ...
Paul Uszak's user avatar
  • 7,469
38 votes
8 answers

How to prototype?

How is prototyping done in a professional EE environment? Do you do your prototypes on breadboards, on copper clad boards, Manhattan style, or do you just draw schematics, order PCBs made and ...
38 votes
8 answers

Altium: How do I flip/mirror components? X and Y don't work

So this seem like a simple question, but I'm trying to flip components in the schematic editor. If I select a component then use the keyboard shortcut X or Y, it brings up a menu and does not slip the ...
user18482's user avatar
  • 381
38 votes
6 answers

Why does there seem to be a missing component in many PCBs?

I've seen some PCBs were some components have been sketched, but they don't seem to be mounted on the board. See, this image (of a PlayStation 2) where the transformer has been drawn: Why is this ...
jinawee's user avatar
  • 1,086
36 votes
4 answers

Why do characteristic impedances matter only when traces are longer than half a wavelength?

Why are characteristic impedances of traces not considered when the traces are shorter than half a wavelength? I've had the same issue with light diffraction, which happens when pinholes are smaller ...
user42875's user avatar
  • 1,324
35 votes
2 answers

What's the purpose of this checkerboard pattern?

This gigabit Ethernet NIC has a checkerboard pattern out of copper etched on the PCB: Each square is electrically isolated. What's the point of adding these? I guess that the PCB isn't filled with a ...
Catherine's user avatar
  • 637
34 votes
10 answers

Looking for a good freeware/open source PCB design software equivalent to Altium [closed]

I am familiar with Altium PCB design software in my workplace. But thats an expensive suite to maintain. Is there any decent enough free software which I can use at home for my pet projects? I have ...
scorpiokid's user avatar
33 votes
5 answers

What reasons are there to avoid vertical through-hole resistors?

I'm working on a layout for a PCB and I need to include a handful of pull-up resistors. The board I'm working on will be a proof of concept, and it is likely I will only need one (and order two). That ...
Justin Trzeciak's user avatar
33 votes
7 answers

Can thin sections of copper traces be used as fuses?

Is it safe to use thin sections of copper traces as one-shot fuses when cost is important, but when it is also vital to protect the rest of the circuitry? Should the solder mask be removed at that ...
Mister Mystère's user avatar
33 votes
10 answers

PCB colors - what's available, and why?

A question so simple I've never thought about it before. Usually I get my PCBs made in standard green, but have been offered a blue for my next revision of an existing (green) board at no extra cost. ...
Dirk Bruere's user avatar
  • 13.5k
32 votes
3 answers

What exactly is prepreg and core in a PCB?

I am trying to wrap my head around the structure of a multilayer PCB, and while I can understand many things, I am not able to grasp the concept of "prepreg" and "core". What do they exactly do? I ...
LoveEnigma's user avatar
31 votes
7 answers

Finding air wires in Eagle

I am almost done routing a board. However, Eagle is telling me that there is still one more wire. I have looked but I just can't seem to find it. Is there a way to make Eagle tell me where it is?
Alexis K's user avatar
  • 2,729
31 votes
11 answers

What is the most amazing PCB artwork you've ever seen?

Have you ever looked at a PCB and burst out laughing? Have you ever looked at a PCB and said "Wow, that is amazing"? Have you ever seen a PCB that artistically expressed criticism of society's ...
31 votes
4 answers

How do I determine the area of copper needed on a PCB to provide adequate heatsinking for a power SMD MOSFET?

I am planning to use the IRFR5305PBF Power MOSFET ( to switch on a load. I have determined that I need an external heatsink with Rthsa &...
dla59's user avatar
  • 347
30 votes
5 answers

What is the purpose of solder mask expansion?

I see recommendations of 2-4 mils for solder mask expansion. But why is it necessary?
ajs410's user avatar
  • 8,421
30 votes
10 answers

Do you layout in mil or mm?

I have been using 10 mil trace with 10 mil spacing. The PCB vendors quote that they like traces down to 7 mil. But then I ran across a PDF showing how to fan out a QFP to get all the signals ...
Robert Deml's user avatar
  • 3,232
30 votes
6 answers

High PCB copper thickness: What are the pitfalls?

We need to carry high currents on a PCB (~30Amps sustained), so we are likely to order our PCBs with high copper thickness. So far we've only used 35 microns (1 oz) in our designs, so 'high thickness' ...
SomethingBetter's user avatar

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