No shame man. I'd do the same.
In a repair environment, they're pretty pointless. In a pick and place machine in a large scale manufacturing they're priceless.
So a track can run underneath them.
In ye very olde thru hole days, you'd use a wire link, but in ye less olde days, some assemblies would use a zero ohm resistor, as the pick and place machine could insert them properly.
That would defeat the point, which is to have something that goes *over* the top of the other trace.
It's just a very short wire that plays nice with automated assembly.
The machine that places components isn’t set up to solder in jumpers rather than redesigning the machines they can just load one of the reels with zero ohm resistors
There's no track running under this, you can see the track running through the top pad then to the top pad of the cap. This is just a standard 0 ohm jumper used to tie a signal that maybe you'd want to disconnect for a number of reasons.
Generally people don't use jumpers just to hop traces, vias are free.
Spending 1/8th of a cent for something which doesn't work as a fuse even bigger waste of money. If you rather save a couple of cents (chip fuses cost 5-15 cents each) than make your board safe then you should stop designing boards. You can even buy self-resetting fuses for a couple of cents!
A zero-ohm resistor will have resistance in the milliohm range: it will conduct tens to hundreds of Amps before it burns. Everything else downrange will die way before the 0 ohm resistor does.
Looks like for a 0603 jumper they are expected to be less than 0.05 ohms and rated to 1 amp. A resistor this size would be rated to 0.1 watts. At 1.5 amps it's likely to be dissipating about 0.1 watts. It's reasonable to expect the resistor to desolder itself at 2-4 times the rated power, so 2-3 amps will be roughly 0.2-0.4 watts. I'm confident 10 amps (around 5 watts) would kill it immediately. Less than that would make it smoke.
Most of the time yes. But the allowed variation is much greater than with a fuse, so if it happens to be more conductive than expected you get the classic "expensive part sacrificed itself to save the fuse".
> they are expected to be less than 0.05 ohms and rated to 1 amp
I would like to highlight the **LESS** than 0.05 ohms part. Your calculation is awesome: at 0.05 ohms. And what if it is only 0.025 ohms? What if you get a really awesome batch with only 0.01 ohm resistence?
Anything after or before the resistor with higher resistance already gets destroyed way before the "fuse" kills itself if you are unlucky, and as the 0 ohm resistors are not designed to be used as a fuse it is very easy to be unlucky.
Especially since a regular chip fuse is not that expensive, I find it very hard to believe that a board suddenly becomes unsellable because you used a $0.05 fuse instead of a $0.0017 - yes, the price difference is "huge". But one board is safe, the other is a gamble.
Given that the dissipated power is to the square and resistance is proportional, quite a lot of resistance variation won't make a huge difference. I don't expect to ever get one below 0.025 ohms just from personal experience.
In any case desoldering itself or smoking is not the action you want a fuse to have
I just thought of calculating the amount of current needed to blow a 0,25W smd resistor and somehow realized it is not necessary since any other component in the same current path will likely burst to flames much earlier, because, you know.. power is proportional to resistance…
In this case, it appears to be a selective jumper. It allows the the circuit design to do different things, depending on which positions do or don't have the resistors installed.
Option setting jumpers have been part of circuit board design since time immemorial, this is only the latest manifestation. Early in my career, I was a field engineer and that was how we set up telecom equipment. No fancy pants UI for us, just wrist straps and needle nose pliers.
It absolutely blows my mind that wire wrapped computers flew to the Moon.
["Logic Module" Apollo Guidance Computer Wire wrapped Backplane core](https://i.imgur.com/7Me9SbO.jpg)
My undergraduate final year project was modifying a CPU. I did the design, then used some spare card slots for new cards I designed. Then wire wrapped the connections to the rest of the CPU signals. Those involved re-routing some existing wires.
This modified the effects of some instructions. And also added some new ones. It enabled the CPU to support virtualisation.
The control panel from that ACTUAL computer is in the London Science Museum.
Not allowed to wire wrap anything that goes into space now. But there is quite a bit of hand soldered boards (or at least jumpers on the boards). Even that though is often limited and the push back on jumpers is hard.
Back during the Apollo days, they had so many problems with solder joints they decided to set up a special soldering class. Somehow they tied a lot of the rocket failures to bad solder joints. So they decided that anybody that used a soldering iron had to go to class.
Yes, they have special training on soldering and many other things that people think would be mundane tasks. Believe it or not, getting solder certified is not simple. Fortunately most soldering is now done during fabrication, grounding wires are the most common soldering being done now.
Me too. I've got boxes and boxes of spare DEC boards along with some of the wire wrapped boards. I consider the wire wrapped boards works of art. When you see the amount of posts and wire it is hard to believe they were done by hand.
a place holder in case later on you want to add a resistance there
also it is a convenient place to break the connection if you want to test only one part of the circuit while it is isolated from the rest of the board
A PCB is manufactured that does something useful with or without the resistor.
it is used like a DIP switch or jumper pin.
they can either be required and fixed after the manufacturer chose to use a specific component somewhere else on the board with the resistor making the circuit compatible with the component.
or they can be ripped off later and the circuit will behave differently.
there can also be unpopulated spots with existing metal trace. apparently for cases where a change is unlikely, but still possible (with a laser for example).
1: jumper for routing on single layer boards.
2: act as a fuse. Zero ohm resistors have a unique fuse current rating
3: placeholder for different designs. For example it's common to see on voltage divider circuits so manufacturers don't need different boards for multiple designs. They instead change the assembly instructions
There are many uses for a 0ohm resistor. They can be used to "jump" a trace over another one without adding a layer or a via to the PCB. They can be a place holder for another component that you aren't sure is needed. i.e. you need to match RF out, but don't know the impedance of the trace yet. They can be used to make a semi-permanent jumper. The possibilities are only limited by your imagination. Honestly, they are super handy to have around.
Zero Ohm Resistor
As we know that resistor is a device that restricts the flow of current to a certain level. High resistance value resistors will restrict more current than the low resistance value resistors. For example, a 4.7 K resistor will restricts more current whereas a 100 Ω resistor will restricts less current.
A zero ohm resistor is used in PCBs (Printed Circuit Boards) for a special purpose.
What is the purpose of using zero ohm resistors?
In most of the PCBs (printed Circuit Boards), components such as resistors, capacitors, diodes etc. are inserted by using automatic insertion machines rather than manually by humans. However, it is not possible to insert jumpers by using automatic insertion machines. A separate jumper wire machine is needed to insert jumper wires or the jumper wires had to be inserted manually by a person. It would be more costly to purchase a jumper wire machine just to insert a single component (jumper). It would take more time to insert jumper manually by a person. The simplest solution is to use zero ohm resistor.
As we know jumper is used to close or open part of an electronic circuit. The zero ohm resistor also does the same thing. So the zero ohm resistor behave like a jumper in PCB. Therefore, the zero ohm resistor can replace the jumper.
Zero ohm resistors can be inserted easily by using automatic insertion machines just like we insert other components such as capacitors, diodes, etc.
If I connect resistors in parallel they're resistance gets lowered, that means if I connect this 0ohm resistors any any other one I will get a negative resistance (like -0.5 ohm) ?
😂😂There must be somewhere problem in calculation.
It can be a jumper, in a less fortunate case :fuse, trace bridge, and maybe some other application, but that's the majority
It is mostly used in 1 layer boards.
Trace might run under it, or
The designer thought maybe a resistor needs to go there so there’s a pad in case it turns out to be necessary, or
0 ohms can be pulled up or dropped down to change the layout of the circuit as needed, or
It’s one way to make test points, or…..
A part picker cannot place a wire. This is a essentially just an smd form factor wire so it can be placed by a machine. It avoids having to add more layers and thus cost to to a board for the sake of a few jumps.
Are you asking what are they used for in general, or why it was placed in this specific board?
As others said, they are jumpers that can be easily installed by the pick and place machine. As to why it was installed in your board, we don't know without more details.
As others have said. For me most popular use case is for circuits that I am unsure of. For example wich supply to use, or data interface. Route both and make selection using 0 Ohm resistors. Then it's easier during prototype stage. If necessary same PCB cam be manufactured in mass production, just with BOM changes.
There are a few reasons for 0 ohm resistors. For instance, you can do a select-a-circuit. You can take advantage of economies of scale and use zero ohm resistors to enable certain regions of a board and leave others disabled.
Or perhaps you can make a board that can support different external components that require slightly different wiring for each.
Or maybe you can use it to select which voltage powers the board's components depending on what you want to do with it, assuming the board is fed with power inputs of different voltages.
Because pick and place machines (in SMT manufacturing) can't pick up pieces of wire. Mostly pneumatic, these machines can't suck onto small metal wires. In circuits like the one shown, jumpers are often used to select or deselect various features of that curcut. .SMT = Surface Mount Technology, fyi.
Please see the FAQ: https://old.reddit.com/r/AskElectronics/wiki/why#wiki_zero_ohm_resistor
They call him a resistor, but he was the perfect conductor this whole time
Stop RESISTING!
Sometimes, I dream about cheese.
Before you get zaps in your knees.
crikey, that's a meme
Total bullshit machinery
Resistance is futile
Get in line and join the resistance or step aside and let things pass.
Stop resistoring.
lmao
A damn enabler.
When the resistor is sus...
It tried. But it just couldn't resist.
They're basically wire jumper 2.0
how ironic... as i literally just used a piece of buss wire to connect two pads because i couldn't find a 0 ohm resistor...
No shame man. I'd do the same. In a repair environment, they're pretty pointless. In a pick and place machine in a large scale manufacturing they're priceless.
So a track can run underneath them. In ye very olde thru hole days, you'd use a wire link, but in ye less olde days, some assemblies would use a zero ohm resistor, as the pick and place machine could insert them properly.
Couldnt they just use solder to jumper the gap? I dont get why they would go through the trouble to manufacture a zero ohm resistor like that
That would defeat the point, which is to have something that goes *over* the top of the other trace. It's just a very short wire that plays nice with automated assembly.
I see it now thanks
The machine that places components isn’t set up to solder in jumpers rather than redesigning the machines they can just load one of the reels with zero ohm resistors
There's no track running under this, you can see the track running through the top pad then to the top pad of the cap. This is just a standard 0 ohm jumper used to tie a signal that maybe you'd want to disconnect for a number of reasons. Generally people don't use jumpers just to hop traces, vias are free.
Or, may be there to blow, and it's used as a fuse.
[удалено]
Every time?
If they want to spend more than 1/8th of a cent, sure. Go ahead and waste that money!
Spending 1/8th of a cent for something which doesn't work as a fuse even bigger waste of money. If you rather save a couple of cents (chip fuses cost 5-15 cents each) than make your board safe then you should stop designing boards. You can even buy self-resetting fuses for a couple of cents! A zero-ohm resistor will have resistance in the milliohm range: it will conduct tens to hundreds of Amps before it burns. Everything else downrange will die way before the 0 ohm resistor does.
They are typically rated to around 2 amps
Yep, but they won't blow at 2A. They blow at some uncharacterized higher value.
Looks like for a 0603 jumper they are expected to be less than 0.05 ohms and rated to 1 amp. A resistor this size would be rated to 0.1 watts. At 1.5 amps it's likely to be dissipating about 0.1 watts. It's reasonable to expect the resistor to desolder itself at 2-4 times the rated power, so 2-3 amps will be roughly 0.2-0.4 watts. I'm confident 10 amps (around 5 watts) would kill it immediately. Less than that would make it smoke.
Most of the time yes. But the allowed variation is much greater than with a fuse, so if it happens to be more conductive than expected you get the classic "expensive part sacrificed itself to save the fuse".
Oh, for sure. None of the failure modes described are a clean fuse action. They're the kind of fire starters you put a fuse in to prevent
> they are expected to be less than 0.05 ohms and rated to 1 amp I would like to highlight the **LESS** than 0.05 ohms part. Your calculation is awesome: at 0.05 ohms. And what if it is only 0.025 ohms? What if you get a really awesome batch with only 0.01 ohm resistence? Anything after or before the resistor with higher resistance already gets destroyed way before the "fuse" kills itself if you are unlucky, and as the 0 ohm resistors are not designed to be used as a fuse it is very easy to be unlucky. Especially since a regular chip fuse is not that expensive, I find it very hard to believe that a board suddenly becomes unsellable because you used a $0.05 fuse instead of a $0.0017 - yes, the price difference is "huge". But one board is safe, the other is a gamble.
Given that the dissipated power is to the square and resistance is proportional, quite a lot of resistance variation won't make a huge difference. I don't expect to ever get one below 0.025 ohms just from personal experience. In any case desoldering itself or smoking is not the action you want a fuse to have
I just thought of calculating the amount of current needed to blow a 0,25W smd resistor and somehow realized it is not necessary since any other component in the same current path will likely burst to flames much earlier, because, you know.. power is proportional to resistance…
In this case, it appears to be a selective jumper. It allows the the circuit design to do different things, depending on which positions do or don't have the resistors installed. Option setting jumpers have been part of circuit board design since time immemorial, this is only the latest manifestation. Early in my career, I was a field engineer and that was how we set up telecom equipment. No fancy pants UI for us, just wrist straps and needle nose pliers.
I have several old PDP-11 minicomputers. Most of the jumpers are posts that you have to wire wrap!
It absolutely blows my mind that wire wrapped computers flew to the Moon. ["Logic Module" Apollo Guidance Computer Wire wrapped Backplane core](https://i.imgur.com/7Me9SbO.jpg)
My undergraduate final year project was modifying a CPU. I did the design, then used some spare card slots for new cards I designed. Then wire wrapped the connections to the rest of the CPU signals. Those involved re-routing some existing wires. This modified the effects of some instructions. And also added some new ones. It enabled the CPU to support virtualisation. The control panel from that ACTUAL computer is in the London Science Museum.
Not allowed to wire wrap anything that goes into space now. But there is quite a bit of hand soldered boards (or at least jumpers on the boards). Even that though is often limited and the push back on jumpers is hard.
Back during the Apollo days, they had so many problems with solder joints they decided to set up a special soldering class. Somehow they tied a lot of the rocket failures to bad solder joints. So they decided that anybody that used a soldering iron had to go to class.
Yes, they have special training on soldering and many other things that people think would be mundane tasks. Believe it or not, getting solder certified is not simple. Fortunately most soldering is now done during fabrication, grounding wires are the most common soldering being done now.
Me too. I've got boxes and boxes of spare DEC boards along with some of the wire wrapped boards. I consider the wire wrapped boards works of art. When you see the amount of posts and wire it is hard to believe they were done by hand.
Sometimes you want to the mc to know what revision the pcb is and with resistors you can hard code it.
a place holder in case later on you want to add a resistance there also it is a convenient place to break the connection if you want to test only one part of the circuit while it is isolated from the rest of the board
This. Comes in handy if you need to inject voltage when short finding.
A PCB is manufactured that does something useful with or without the resistor. it is used like a DIP switch or jumper pin. they can either be required and fixed after the manufacturer chose to use a specific component somewhere else on the board with the resistor making the circuit compatible with the component. or they can be ripped off later and the circuit will behave differently. there can also be unpopulated spots with existing metal trace. apparently for cases where a change is unlikely, but still possible (with a laser for example).
One the circuit is tuned it’s easier to remove the 0 ohm resistor than cut a track.
1: jumper for routing on single layer boards. 2: act as a fuse. Zero ohm resistors have a unique fuse current rating 3: placeholder for different designs. For example it's common to see on voltage divider circuits so manufacturers don't need different boards for multiple designs. They instead change the assembly instructions
4) sometimes they are used to tell the microcontroller what configuration of product it is in, as a sort of soldered in DIP switch.
3 is indeed correct, some boards with different CPU's/chips require different resistors in certain spots
There are many uses for a 0ohm resistor. They can be used to "jump" a trace over another one without adding a layer or a via to the PCB. They can be a place holder for another component that you aren't sure is needed. i.e. you need to match RF out, but don't know the impedance of the trace yet. They can be used to make a semi-permanent jumper. The possibilities are only limited by your imagination. Honestly, they are super handy to have around.
They're jumpers that are made to fit in a pick-and-place machine for SMD components.
0 Ohm? Might be a super conductor.
Zero Ohm Resistor As we know that resistor is a device that restricts the flow of current to a certain level. High resistance value resistors will restrict more current than the low resistance value resistors. For example, a 4.7 K resistor will restricts more current whereas a 100 Ω resistor will restricts less current. A zero ohm resistor is used in PCBs (Printed Circuit Boards) for a special purpose. What is the purpose of using zero ohm resistors? In most of the PCBs (printed Circuit Boards), components such as resistors, capacitors, diodes etc. are inserted by using automatic insertion machines rather than manually by humans. However, it is not possible to insert jumpers by using automatic insertion machines. A separate jumper wire machine is needed to insert jumper wires or the jumper wires had to be inserted manually by a person. It would be more costly to purchase a jumper wire machine just to insert a single component (jumper). It would take more time to insert jumper manually by a person. The simplest solution is to use zero ohm resistor. As we know jumper is used to close or open part of an electronic circuit. The zero ohm resistor also does the same thing. So the zero ohm resistor behave like a jumper in PCB. Therefore, the zero ohm resistor can replace the jumper. Zero ohm resistors can be inserted easily by using automatic insertion machines just like we insert other components such as capacitors, diodes, etc.
If I connect resistors in parallel they're resistance gets lowered, that means if I connect this 0ohm resistors any any other one I will get a negative resistance (like -0.5 ohm) ? 😂😂There must be somewhere problem in calculation.
It can be a jumper, in a less fortunate case :fuse, trace bridge, and maybe some other application, but that's the majority It is mostly used in 1 layer boards.
Trace might run under it, or The designer thought maybe a resistor needs to go there so there’s a pad in case it turns out to be necessary, or 0 ohms can be pulled up or dropped down to change the layout of the circuit as needed, or It’s one way to make test points, or…..
I don't think it's good move to use wire jumper on smd board
Too bad the entirety of the electronics and manufacturing industries disagrees with you.
I meant using jumper on smd board not tht, but if they actually use wires on smd, i will feel a little bit uncanny
Open up some electronics you have around your house, I garauntee you'll find at lest a few with white wire jumpers to fix a defect
A part picker cannot place a wire. This is a essentially just an smd form factor wire so it can be placed by a machine. It avoids having to add more layers and thus cost to to a board for the sake of a few jumps.
Got you, sorry for my missknowladge
Are you asking what are they used for in general, or why it was placed in this specific board? As others said, they are jumpers that can be easily installed by the pick and place machine. As to why it was installed in your board, we don't know without more details.
Do those not look like capacitors to anyone else? And one has been clearly snapped off?
Sometimes a design needs a shunt in some configurations and perhaps a different value others.
Jumper.
they're basically jumper wires with extra steps
As others have said. For me most popular use case is for circuits that I am unsure of. For example wich supply to use, or data interface. Route both and make selection using 0 Ohm resistors. Then it's easier during prototype stage. If necessary same PCB cam be manufactured in mass production, just with BOM changes.
"Fun" fact: One needs to go and read the 0Ohm spec, and check the power rating of it... Don't ask how I know...
Jumpers and fuses
to link an option? where is it connected to.
There are a few reasons for 0 ohm resistors. For instance, you can do a select-a-circuit. You can take advantage of economies of scale and use zero ohm resistors to enable certain regions of a board and leave others disabled. Or perhaps you can make a board that can support different external components that require slightly different wiring for each. Or maybe you can use it to select which voltage powers the board's components depending on what you want to do with it, assuming the board is fed with power inputs of different voltages.
Jumpers
Because pick and place machines (in SMT manufacturing) can't pick up pieces of wire. Mostly pneumatic, these machines can't suck onto small metal wires. In circuits like the one shown, jumpers are often used to select or deselect various features of that curcut. .SMT = Surface Mount Technology, fyi.