3 ms·

Random question related to the photos of the phone's motherboard: Why does the PCB have so many holes in it? It looks very unusual. There's quite a large area w

Random question related to the photos of the phone's motherboard: Why does the PCB have so many holes in it? It looks very unusual. There's quite a large area with nothing but holes.

cromka 2y ago
Weight reduction, presumably?
- nikau 2y ago
  Damn you just gave someone at the apple marketing team an end of year bonus: "Inspired by the starter key of the legendary Porsche 917..."
joshp_ 2y ago
If you’re referring to the edges then those are vias. Apple has been stacking PCBs like this since the iPhone X. See step 14 in https://www.ifixit.com/Teardown/iPhone+X+Teardown/98975 https://www.ifixit.com/Teardown/iPhone+X+Teardown/98975
deleted 2y ago
[deleted]
lgeorget 2y ago
Not exactly sure what you're looking at, but aren't they just stitching vias placed there for shielding purpose: https://resources.altium.com/p/everything-you-need-know-about-stitching-vias https://resources.altium.com/p/everything-you-need-know-abou...?
lnsru 2y ago
Are you sure these are holes? Looks like soldering pads to me.
Luc 2y ago
I'm not quite up to date on modern electronics, but I assume they are ground-stitching vias - connections to the ground plane optimized in size and number to reduce electromagnetic interference. Here's a decent explanation: https://circuitcellar.com/research-design-hub/basics-of-design/lets-understand-ground-stitching-vias/ https://circuitcellar.com/research-design-hub/basics-of-desi...
- leejoramo 2y ago
  Thanks for that link. “Circuit Cellar” reminded me of something, and led me to find this is the descendant of Steve Ciarcia’s 1980s BYTE magazine column. After several iterations, it looks like Steve sold it to an employee.
grues-dinner 2y ago
They're not holes (though there are probably many vias there to connect to the ground planes and signal traces, but on this board the vias will be tiny and will either be under the solder resist or under the solder blobs). They're soldering lands for where the two halves of the mainboard are soldered together into a sandwich via some kind of thicker PCB interposer, which can carry the signals between the boards. This is probably an order of magnitude or more cheaper and far, far less volume-consuming and way more robust than standard mezzanine connectors. But rather tricky to repair! Look at the video in the article around 7:29. The article calls out the soldered-on heatsink plate, but it's not very clear from the pictures how it actually works in the stack-up without reference to the video. I don't know why they didn't do a better close up of both sides of that, maybe it's in a different article.

Random question related to the photos of the phone's motherboard: Why does the PCB have so many holes in it? It looks very unusual. There's quite a large area with nothing but holes.

cromka 2y ago

Weight reduction, presumably?

nikau 2y ago
Damn you just gave someone at the apple marketing team an end of year bonus: "Inspired by the starter key of the legendary Porsche 917..."

joshp_ 2y ago

If you’re referring to the edges then those are vias. Apple has been stacking PCBs like this since the iPhone X. See step 14 in https://www.ifixit.com/Teardown/iPhone+X+Teardown/98975 https://www.ifixit.com/Teardown/iPhone+X+Teardown/98975

deleted 2y ago

[deleted]

lgeorget 2y ago

Not exactly sure what you're looking at, but aren't they just stitching vias placed there for shielding purpose: https://resources.altium.com/p/everything-you-need-know-about-stitching-vias https://resources.altium.com/p/everything-you-need-know-abou...?

lnsru 2y ago

Are you sure these are holes? Looks like soldering pads to me.

Luc 2y ago

I'm not quite up to date on modern electronics, but I assume they are ground-stitching vias - connections to the ground plane optimized in size and number to reduce electromagnetic interference. Here's a decent explanation: https://circuitcellar.com/research-design-hub/basics-of-design/lets-understand-ground-stitching-vias/ https://circuitcellar.com/research-design-hub/basics-of-desi...

leejoramo 2y ago
Thanks for that link. “Circuit Cellar” reminded me of something, and led me to find this is the descendant of Steve Ciarcia’s 1980s BYTE magazine column. After several iterations, it looks like Steve sold it to an employee.

grues-dinner 2y ago

They're not holes (though there are probably many vias there to connect to the ground planes and signal traces, but on this board the vias will be tiny and will either be under the solder resist or under the solder blobs). They're soldering lands for where the two halves of the mainboard are soldered together into a sandwich via some kind of thicker PCB interposer, which can carry the signals between the boards. This is probably an order of magnitude or more cheaper and far, far less volume-consuming and way more robust than standard mezzanine connectors. But rather tricky to repair! Look at the video in the article around 7:29. The article calls out the soldered-on heatsink plate, but it's not very clear from the pictures how it actually works in the stack-up without reference to the video. I don't know why they didn't do a better close up of both sides of that, maybe it's in a different article.