Go Down

Topic: Min via hole size? (Read 558 times) previous topic - next topic

jonisonvespaa

hello, just wondering whats the normal min size for via holes?
thank you

CrossRoads

I use 12 mil for 8 & 10 mil wide traces.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

jonisonvespaa

#2
Dec 09, 2016, 03:55 pm Last Edit: Dec 09, 2016, 04:06 pm by jonisonvespaa
thanks, can most pcb manufactures handke 12mi?

DVDdoug

Right...  It depends on the capabilities of the PCB manufacturer.    From what I've heard, they can be "microscopic" and some small boards have many-thousands of vias. (I assume that would be something like an iPhone or an Apple Watch.)     

But, you can sometimes get a bad (open) via and if it was me, I'd make them big enough to solder a 30 AWG wire through to make a repair.  (Where I work, the vias are too small for that and sometimes we have to scrap an assembled board.) 

And assuming you are a hobbyist, you usually want something cheap & reliable in small quantities so you don't want to be pushing the state-of-the-art.   The more you push the limits/tolerances the more likely you are to have a defect and the cost may go up.  Design the board to your requirements...  Don't use the smallest traces and the smallest vias just because they manufacturer says they can do it...

CrossRoads

I use iteadstudio for PCBs, 12mil vias/10mil traces are not a problem. I have not had a bad one in 6+ years worth of boards.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

jonisonvespaa

Ok ill use iteadstudio be simpler
Thank you

DrAzzy

#6
Dec 09, 2016, 07:54 pm Last Edit: Dec 09, 2016, 07:57 pm by DrAzzy
Min size for vias will be specified by your board house, along with minimum clearance/etc - it's one of the key parameters that they list when specifying their capabilities. Some will even give an eagle .dru file (or similar for their favorite tools) that has that already spec'ed.
ATtiny core for 841+1634+828 and x313/x4/x5/x61/x7/x8 series Board Manager:
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts (some assembled), mosfets and awesome prototyping board in my store http://tindie.com/stores/DrAzzy

Paul_KD7HB

And don't put vias under components!

Paul

CrossRoads

Why not? With quad flat packs, you need them under parts a lot of times.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

MorganS

You would normally avoid putting vias inside the pads for components but even that rule is not necessary for some manufacturing processes. (The via itself is fine but it makes a drain hole so that solder can escape from under the component foot during the soldering process.)

Vias under components, usually no problem unless the component must sit absolutely flat to the board, like a temperature sensor or something. If your process makes unusually thick vias, it may lift a small component like a resistor too high for proper soldering.
"The problem is in the code you didn't post."

Paul_KD7HB

You would normally avoid putting vias inside the pads for components but even that rule is not necessary for some manufacturing processes. (The via itself is fine but it makes a drain hole so that solder can escape from under the component foot during the soldering process.)

Vias under components, usually no problem unless the component must sit absolutely flat to the board, like a temperature sensor or something. If your process makes unusually thick vias, it may lift a small component like a resistor too high for proper soldering.
Morgan, that is what I was thinking about, triggered by a customer complaint about a component setting too high for the enclosure the board had to go in. My manger pointed out the via and solder mask under the component. The engineer replied "Oh, right". I don't know what they did to solve the problem.

Paul

Go Up