Prev: MicroGem DTV converter gets pretty hot
Next: Diodes for boost converter SPICE parameters
From: Grant on 1 Jul 2010 19:59
On Thu, 01 Jul 2010 15:12:53 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>On Thu, 01 Jul 2010 18:49:27 GMT, Jan Panteltje
><pNaonStpealmtje(a)yahoo.com> wrote:
>
>>On a sunny day (Thu, 01 Jul 2010 09:44:48 -0700) it happened John Larkin
>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
>><r0gp26d6soituurqdhc1bkqquunfpos1de(a)4ax.com>:
>>
>>>>http://www.allfavorpcb.com/ ?
>>>
>>>We ordered the boards from Phase 3
>>>
>>>http://www.p3ti.com/
>>>
>>>who apparently brokered them to Allfavor. We ordered four boards,
>>>quick turn, electrically tested, 6 layers, screened both sides, 8/8
>>>rules, for $175 each.
>>
>>That is a good price, and it helps to have a contact in your own country.
>>
>>
>>>I guess it's cheaper to email the gerbers to China and fly the boards
>>>back, than to make them here.
>>>
>>>That's a pretty good photo, for hand-held. The Allfavor bug is pretty
>>>small. That's not even the original full-res picture. The silkscreen
>>>reference designators are 60 mils high and are nice and sharp.
>>
>>I had trouble reading the text on the IC packages, could hardly make out 'Xilinx'
>>in the big one at top pright.
>>Did you erase the text or all all those chips that way?
>
>That's the way most chips are these days. I think it's laser marking
>on the epoxy. If the illumination is straight-on, the markings are
>just about invisible.

Yes, with my eyesight I need to photograph parts in order to read the
marking, so I take several shots at different angles hoping to catch
some contrast with the marking vs the package.
>
>There are three SSRs, upper left, that actually have silkscreened part
>numbers, and whose markings are visible with most any illumination.
>
>>
>>
>>>It seems to work so far. No assembly problems, just one complaint
>>>about a bottomside part that can't be glued so has to be hand
>>>soldered. The twelve isolated channel power supplies are fine, and
>>>we're talking jtag to the ARMs and blinking LEDs. We'll test the
>>>analog stuff today.
>>
>>Does it run hot?
>
>It shouldn't, at least until we get the 4-20 mA stuff running. Each
>channel can dissipate up to 700 mW of loop power. With just the CPUs
>and stuff running, everything is cool. VME crates have lots of fans.
>
>One thing I do on a new board is feel all the parts to see if anything
>is warm.
>
>>
>>
>>>To power the 3 volt ADC reference bandgaps in each channel, I fudged
>>>the 3.3 volt supply up to 3.5 and just used a resistor. I did suggest
>>>a beta-limited PNP current source, to predictable squealing, but that
>>>would have been one more part for about the same performance. LM4040s
>>>aren't very picky about operating current.
>>>
>>>I wrote the manual (21 pages so far, more to come) and a 16 page
>>>design notes document, so my software guy has all the input and math
>>>he needs to program the ARMs. We'll release the design doc to the
>>>library for future reference.
>>
>>Yes sometimes he documentation is even as much work or more then the design,
>>I remember one requirement from gov: All parts must be addressed in the docs.
>>
>>
>>I am impressed by the 'fill rate', I mean how much you got on that bord.
>
>It has parts on the back, too!

Yes, impressive, looks like a bought one ;)
>
>>Hope it works,
>
>Yeah, it's always a little tense before it works, hoping there's no
>fatal blunder.
>
No smoke so far, can't be too bad?

Grant.
From: John Larkin on 1 Jul 2010 20:32
On Fri, 02 Jul 2010 09:59:11 +1000, Grant <omg(a)grrr.id.au> wrote:

>On Thu, 01 Jul 2010 15:12:53 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>
>>On Thu, 01 Jul 2010 18:49:27 GMT, Jan Panteltje
>><pNaonStpealmtje(a)yahoo.com> wrote:
>>
>>>On a sunny day (Thu, 01 Jul 2010 09:44:48 -0700) it happened John Larkin
>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in
>>><r0gp26d6soituurqdhc1bkqquunfpos1de(a)4ax.com>:
>>>
>>>>>http://www.allfavorpcb.com/ ?
>>>>
>>>>We ordered the boards from Phase 3
>>>>
>>>>http://www.p3ti.com/
>>>>
>>>>who apparently brokered them to Allfavor. We ordered four boards,
>>>>quick turn, electrically tested, 6 layers, screened both sides, 8/8
>>>>rules, for $175 each.
>>>
>>>That is a good price, and it helps to have a contact in your own country.
>>>
>>>
>>>>I guess it's cheaper to email the gerbers to China and fly the boards
>>>>back, than to make them here.
>>>>
>>>>That's a pretty good photo, for hand-held. The Allfavor bug is pretty
>>>>small. That's not even the original full-res picture. The silkscreen
>>>>reference designators are 60 mils high and are nice and sharp.
>>>
>>>I had trouble reading the text on the IC packages, could hardly make out 'Xilinx'
>>>in the big one at top pright.
>>>Did you erase the text or all all those chips that way?
>>
>>That's the way most chips are these days. I think it's laser marking
>>on the epoxy. If the illumination is straight-on, the markings are
>>just about invisible.
>
>Yes, with my eyesight I need to photograph parts in order to read the
>marking, so I take several shots at different angles hoping to catch
>some contrast with the marking vs the package.

Low-angle side illumination is usually best.

One old trick is to swipe the top of the part with a q-tip dipped in
isopropyl alcohol. There's a brief flash of time, as the alcohol
evaporates, when the markings are more visible.

Grrrr. Why can't they apply a coating to the top of the epoxy that
laser-marks better? What would that cost, 1/100 of a cent?

And why can't they mark capacitors?

John


First  |  Prev  | 
Pages: 1 2
Prev: MicroGem DTV converter gets pretty hot
Next: Diodes for boost converter SPICE parameters