[Arm-netbook] HDMI High-Frequency Layout: Recommendations

Luke Kenneth Casson Leighton lkcl at lkcl.net
Wed Aug 30 11:07:16 BST 2017


On Wed, Aug 30, 2017 at 7:59 AM, Richard Wilbur
<richard.wilbur at gmail.com> wrote:
>  I have a question about one of the traces:  In the layout picture it appears that something resembling a via coincides with HTX1P following the second wiggle after the trace turns NE.  If it is a via, what is it doing there?  If not, what is it?

 you've lost me, sorry. i don't know if you have access to an image
editor but an arrow pointing would help - i know you're using an
iphone so that might be a leetle awwkward...

> Of course, hopefully you never have need of soldering or desoldering the μHDMI connector by hand.  Looks best left to the oven.

 yyeah this connector is a bitch to take off by hand.  the heatgun
literally melts the plastic inside the case and that's it, it's done -
in the bin.  with the added risk that it can strip off the pads on its
way up.

 then when you try and put a replacement on, that melts too, the pins
move off the same plane and it's game over for *that* connector, too.

 this is why we'll be doing a test run of some low-cost 2-layer PCBs
(1in x 1in) just with the DC3 land pattern and some test jumpers,
which will go through the oven to make sure that the DC3 actually sits
down and all pins connect to their pads.

 lot less risky than $USD 2,000 for complete PCBs only to find that
after 5-8 weeks yet another footprint layout doesn't work.....

l.



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