Re: Does anyone have 15C LE dissection pics?



#6

..in response to message #26 Posted by Eric Smith on 22 Sept 2011, 5:45 p.m.,
..in response to message #25 by uhmgawa
Quote:
This is what makes it particularly bizarre that the 15C LE has moved to SMT assembly.

I still boggle why following up directly to a thread merely a
month old in this forum is verboten, but anyway..

I finally heard back from Atmel (through their 3rd party die
reseller) who declined to quote our bid on the at91sam7l128
citing the device in die form was either in, or will soon
be EOL. I speculate that was the primary motivation for
the board layout change to accommodate the 128 lqfp in the
new ARM voyagers.

Not too surprising as the sam7 is getting rather long in the
tooth and there hasn't been any follow on AFAICT to either
l64/l128 version. Also other more recent vendor designs exist
with improved performance/power capability. Yet despite its age
the sam7l appears to still have some competitive differential
particularly given its price point.


#7

Check this archived thread, Djj posted some great pics to photobucket from his keyboard modification.

Katie posted some dissection pictures too further back in the archive.


#8

Quote:
Check this archived thread, Djj posted some great pics to photobucket from his keyboard modification.

M1.4 x 4mm (or perhaps x 5mm depending on washer thickness) is
just about ideal. I'd initially tried M1.2 x 5mm screws
however due to the thread major diameter routinely running
undersize for such a fine pitch, an M1.2 screw doesn't have much
(if any) penetration into the stake void walls. I also expect
substantial variation exists relative to screws and enclosure
molding run.

However the M1.4 thread needed to be formed with a tap in my
case as the fit was too snug. Machine screws will wedge
vs. cutting threads and unless tapped there is a risk of
randomly splitting the heat stake. Another possibility is to
intentionally slice the stakes in half lengthwise allowing
a controlled expansion/wedging within the pcb. But use of a
plug tap is probably an overall simpler approach.


#9

Read the whole thread. . . He posted the picture link further down the thread.


#10

Quote:
Read the whole thread. . .

Yes, I had.

My point rather was I'd originally suggested use of M1.2 screws
after casually gauging the stake voids and neglecting to
compensate for the typical clearance-reduced major diameter.
So M1.4 is a better standard size for the task.

Still the use of a machine screw in ABS is unorthodox. The
no-holds-barred approach would be to (slightly) drill out each
stake void and heat-press in a threaded section of 1.6mm (1/16")
brass tubing tapped in advance for a M1.4x0.3mm thread.

While the above admittedly is extreme for an ARM voyager,
true hardship cases exist begging for similar treatment such
as the 42s "write once" enclosure.


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