Author Topic: Can't find pcb breaker footprint anywhere  (Read 1476 times)

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Offline teslinius

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Can't find pcb breaker footprint anywhere
« on: August 19, 2021, 10:50:27 pm »
I can't find anywhere in easy eda smd "breakers", i don't know if that's the correct name but usually on pcb's it say BK and it looks like pic related, anyone know what's the real name for this? Tried searching on the internet didn't find it. It's use is for easily interrupting traces.
 

Online jpanhalt

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Re: Can't find pcb breaker footprint anywhere
« Reply #1 on: August 19, 2021, 10:55:13 pm »
Maybe if you showed a real picture or gave a link your query would make sense.

Consider a wire jumper if you want an easily interrupted trace.  Or, draw something that can be easily cut or scrapped with a knife blade.
« Last Edit: August 19, 2021, 10:57:37 pm by jpanhalt »
 

Offline Alex Eisenhut

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Re: Can't find pcb breaker footprint anywhere
« Reply #2 on: August 20, 2021, 09:35:09 pm »
They have many names like cracker, mouse bite, break off, you can simply ask your fabricator for their template.
You can either implement them or simply ask them to add them, but you better be careful and not route or place parts too close!
Hoarder of 8-bit Commodore relics and 1960s Tektronix 500-series stuff.
 

Offline bpiphany

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Re: Can't find pcb breaker footprint anywhere
« Reply #3 on: August 21, 2021, 10:35:59 am »
My guess is he's looking for a "trace fuse" like this
Image stolen from: https://electronics.stackexchange.com/questions/200350/can-thin-sections-of-copper-traces-be-used-as-fuses
 

Offline thm_w

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Re: Can't find pcb breaker footprint anywhere
« Reply #4 on: August 23, 2021, 09:31:32 pm »
You'll want to draw that yourself.
I prefer the solder bridge method, have two pads close together, then dab a drop of solder across them to complete the connection. Easier than dealing with cutting through a trace.

https://electronics.stackexchange.com/questions/261106/solder-bridge-in-schematics-and-0-resistors
 

Offline Shadowfire

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Re: Can't find pcb breaker footprint anywhere
« Reply #5 on: September 15, 2021, 08:54:44 pm »
What is the purpose of the breaker?
Is it for interrupting the circuit for the purposes of debug?  If so, just use an appropriately sized 0-ohm resistors (0402's are usually good for loads up to 1 Amp, check the datasheet to make sure.)
If its for overcurrent protection, first check if a PTC is suitable for the job.  If you insist on using a trace as a fuse, then the Saturn PCB toolkit has a "Fusing Current" tab that can help you with this.
Generally speaking, I wouldn't use fusing current for OCP unless the application couldn't deal with the IR drop of a normal fuse or PTC.  When a PTC blows, you can fix whatever the problem is and the board still works.
 When a surface mounted fuse blows, you can fix the problem and replace the fuse.  When a fusing-current trace blows, you need a completely new PCB assembly.  Also, note that a fusing current trace "trip" is "extraordinarily hot", copper melts at over 1000°C.
« Last Edit: September 15, 2021, 08:57:48 pm by Shadowfire »
 

Offline bpiphany

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Re: Can't find pcb breaker footprint anywhere
« Reply #6 on: September 16, 2021, 06:23:01 am »
Was given the pleasure of repairing my induction hob some years back. Changing a rectifier and some IGBTs. There was also a "blown" fusible copper trace. Interestingly there were through hole holder for a 6.35mm fuse mounted at the ends of the trace. I wonder how much they saved on the BOM by leaving the fuse out. Why not take out the holders as well. I find it very unlikely that they actually expect anyone to repair the board. I'm pretty sure they will just replace the whole board if you ask them for a repair.
 


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