[time-nuts] OCXO Support Board

[John Ackermann N8UR]

On 5/14/20 5:07 PM, Bob kb8tq wrote:

> No, the cheap board houses don’t check for this stuff. They just build and send it
> back. If there’s a gotcha, you get it on the board. 

I was pleasantly surprised last week when Seeed Fusion contacted me to
point out a problem where two vias were too close together (by a couple
of thousandths).  They asked if they could reduce the hole diameters
slightly to correct.  I agreed, they made the change, and the boards are
with DHL right now.  So they do have a process to kick at least some
issues to human beings for resolution, rather than just rejecting the job.

BTW, two things I've learned from my current project:

1.  Seeed claims that they can do down to 4mil trace width and spacing,
and down to 0.2mm holes, but those add extra charges.  For their $4.95
for ten boards deal, the minimums are 6mils and 0.5mm holes (why can't
they pick one dimension system for the specs???)  Go smaller and the
price goes up 10x or more.

2.  Where I had the clearance problem was on a USB C connector.
Whatever advantages they have, they are a pain to route and solder.  The
one I used (which seems fairly common) has both through hole and SMT
pads, and the space to get all the signals lines connected and routed is
very, very tight.  The smaller trace and hole sizes would have made the
job easier, but I wasn't willing to jack up the cost for that.

John
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