Hi Everyone,
I have attached a pcbnew screenshot of a HDMI micro footprint, on a 4 layer board, with components on top. I am
using the bottom layer also for routing. In the image, I was not able to get a proper strategy for routing off the inner row of pins, so I pulled tracks into the no-go zone (not shown, but it is the area within c1-c3-c4-c2 with 0.59mm clearance below the outer edge of c1-c2. I dropped vias to the bottom copper, and routed onwards (green traces) from there.
I need comments on what you would do? Is this the only possible way?
I am also constrained by costs/mfg guidelines, so the traces I chose are 5/5 mils.
I can only offer basic rules to get started.
Don’t route traces under the pads.
Drop via’s for every pad as close to the device as you can and route the top copper from the pads to those via’'s. You can delete them later if not needed.
Pick and stuck to a rule. Top cope for vertical traces and bottom layer for horizontal traces.
The rest I’m sure will fall in to place.
http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=slla324&fileType=pdf
See the vias close to the pads in that pdf?
I don’t get the c1-c4, aren’t those pads all on the same potential due to how the housing is made - essentially shielding ground?
Also, why does your pad 19 have a different clearance/soldermask/etc. than the others?
I hope you didn’t set those values on a per-pad-appearance…
Those values should be - in 99% of the cases - dictated by the pcb setting.
For better routing I’d suggest to get rid of the visualization of the soldermask layer you got visible (purple) and then also switch pads into outline mode (toolbar on the left).
What are the settings for the vias you got there and what can your fab produce reliably?
As you’re already on OpenGL mode, you might use the shove-router function, as your tracks don’t use all the available space as it is… you can go way tighter there and get all tracks back out and don’t need to use the ‘sides’.
The tricky part really boils down to how small your vias can be and how close to the pins you can place them (without wicking the solder away during reflow) - that’s the obstacle here.
1 Like