Cantaloupes

John Larkin · Aug 14, 2005

The first rule about captaloupes is never buy them at Safeway.

But today they had Tuscan cantaloupes, which are bigger that the
regular ones, a bit oblong, and have recessed stripes from pole to
pole, sort of green lines of longitiude. So I sniffed one (second rule
of cantaloupes: don't buy it if it doesn't smell like a cantaloupe)
and it smelled really good so I got one. Highly recommended. Actually,
they had a toofer for Safeway Select Club Members (ie, us) so I got
two. Had to give one away, they're so huge.

Still checking this board. Tedious. It reports a jillion clearance
errors at 8/8 design rules, just from all the pins on the US8 parts.

John

Jim Thompson · Aug 14, 2005

On Sun, 14 Aug 2005 14:47:28 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

The first rule about captaloupes is never buy them at Safeway.

But how about cantaloupes ?

But today they had Tuscan cantaloupes, which are bigger that the
regular ones, a bit oblong, and have recessed stripes from pole to
pole, sort of green lines of longitiude. So I sniffed one (second rule
of cantaloupes: don't buy it if it doesn't smell like a cantaloupe)
and it smelled really good so I got one. Highly recommended. Actually,
they had a toofer for Safeway Select Club Members (ie, us) so I got
two. Had to give one away, they're so huge.

[snip the work stuff :-]

What we call cantaloupes aren't, they're actually some other melon,
the name I can't recall right now.

Safeway is so-so for melons, just make sure they pass *both* smell and
"press the stem button" tests ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

John Fields · Aug 14, 2005

On Sun, 14 Aug 2005 14:47:28 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

The first rule about captaloupes is never buy them at Safeway.

But today they had Tuscan cantaloupes, which are bigger that the
regular ones, a bit oblong, and have recessed stripes from pole to
pole, sort of green lines of longitiude. So I sniffed one (second rule
of cantaloupes: don't buy it if it doesn't smell like a cantaloupe)
and it smelled really good so I got one. Highly recommended. Actually,
they had a toofer for Safeway Select Club Members (ie, us) so I got
two. Had to give one away, they're so huge.

---
And?

We like ours with our Blue Bell (from Brenham, Texas, "Where we eat
all we can and we sell the rest") Natural Vanilla Bean ice cream in
the cavity after the seeds have been removed. Yum...
---

Still checking this board. Tedious. It reports a jillion clearance
errors at 8/8 design rules, just from all the pins on the US8 parts.

---
USB???

--
John Fields
Professional Circuit Designer

John Larkin · Aug 14, 2005

On Sun, 14 Aug 2005 15:02:08 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Sun, 14 Aug 2005 14:47:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

The first rule about captaloupes is never buy them at Safeway.

But how about cantaloupes ?

If you get tired of designing IC's, you could always be a 3rd grade
English teacher.

But today they had Tuscan cantaloupes, which are bigger that the
regular ones, a bit oblong, and have recessed stripes from pole to
pole, sort of green lines of longitiude. So I sniffed one (second rule
of cantaloupes: don't buy it if it doesn't smell like a cantaloupe)
and it smelled really good so I got one. Highly recommended. Actually,
they had a toofer for Safeway Select Club Members (ie, us) so I got
two. Had to give one away, they're so huge.

[snip the work stuff :-]

That would be nice.

What we call cantaloupes aren't, they're actually some other melon,
the name I can't recall right now.

Musk melons, apparently:

http://www.mariquita.com/articles/None.dare.call.html

Our Safeways is all ripped up now, the whole ceiling supported by huge
jacks. They're converting it to a "Lifestyle" Safeway. The good part
is that they now stock Perugina chocolates and the black Toberlone
triangles, instead of Hershey and Cadbury.

John

John Larkin · Aug 14, 2005

On Sun, 14 Aug 2005 18:26:11 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Sun, 14 Aug 2005 14:47:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

The first rule about captaloupes is never buy them at Safeway.

But today they had Tuscan cantaloupes, which are bigger that the
regular ones, a bit oblong, and have recessed stripes from pole to
pole, sort of green lines of longitiude. So I sniffed one (second rule
of cantaloupes: don't buy it if it doesn't smell like a cantaloupe)
and it smelled really good so I got one. Highly recommended. Actually,
they had a toofer for Safeway Select Club Members (ie, us) so I got
two. Had to give one away, they're so huge.

---
And?

We like ours with our Blue Bell (from Brenham, Texas, "Where we eat
all we can and we sell the rest") Natural Vanilla Bean ice cream in
the cavity after the seeds have been removed. Yum...
---

Still checking this board. Tedious. It reports a jillion clearance
errors at 8/8 design rules, just from all the pins on the US8 parts.

---
USB???

No, it's this nasty little thing. Hard to solder, darn near impossible
to probe:

http://www.fairchildsemi.com/products/logic/pdf/mab08a.pdf

John

Jim Thompson · Aug 14, 2005

On Sun, 14 Aug 2005 19:55:37 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

[snip]

US8. The recommended footprint has 0.3 mm pads on 0.5mm spacing, so
the clearance is 0.2mm (an RCH under 8 mils).

Best regards,
Spehro Pefhany

480)460-2350 | |
| E-mail Address at Website Fax

Spehro Pefhany · Aug 14, 2005

On Sun, 14 Aug 2005 18:26:11 -0500, the renowned John Fields
<jfields@austininstruments.com> wrote:

On Sun, 14 Aug 2005 14:47:28 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

The first rule about captaloupes is never buy them at Safeway.

But today they had Tuscan cantaloupes, which are bigger that the
regular ones, a bit oblong, and have recessed stripes from pole to
pole, sort of green lines of longitiude. So I sniffed one (second rule
of cantaloupes: don't buy it if it doesn't smell like a cantaloupe)
and it smelled really good so I got one. Highly recommended. Actually,
they had a toofer for Safeway Select Club Members (ie, us) so I got
two. Had to give one away, they're so huge.

---
And?

We like ours with our Blue Bell (from Brenham, Texas, "Where we eat
all we can and we sell the rest") Natural Vanilla Bean ice cream in
the cavity after the seeds have been removed. Yum...
---

Still checking this board. Tedious. It reports a jillion clearance
errors at 8/8 design rules, just from all the pins on the US8 parts.

---
USB???

US8. The recommended footprint has 0.3 mm pads on 0.5mm spacing, so
the clearance is 0.2mm (an RCH under 8 mils).

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Jim Thompson · Aug 14, 2005

On Sun, 14 Aug 2005 20:41:38 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Sun, 14 Aug 2005 16:55:04 -0700, the renowned Jim Thompson
thegreatone@example.com> wrote:

On Sun, 14 Aug 2005 19:55:37 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

[snip]

US8. The recommended footprint has 0.3 mm pads on 0.5mm spacing, so
the clearance is 0.2mm (an RCH under 8 mils).

Best regards,
Spehro Pefhany

I dated a red-head in high school just to check that out ;-)

...Jim Thompson

Is that a micrometer in your pocket, or are you just glad to see me?

;-)

Best regards,
Spehro Pefhany

480)460-2350 | |
| E-mail Address at Website Fax

Spehro Pefhany · Aug 14, 2005

On Sun, 14 Aug 2005 16:55:04 -0700, the renowned Jim Thompson
<thegreatone@example.com> wrote:

On Sun, 14 Aug 2005 19:55:37 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

[snip]

US8. The recommended footprint has 0.3 mm pads on 0.5mm spacing, so
the clearance is 0.2mm (an RCH under 8 mils).

Best regards,
Spehro Pefhany

I dated a red-head in high school just to check that out ;-)

...Jim Thompson

Is that a micrometer in your pocket, or are you just glad to see me?

;-)

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Winfield Hill · Aug 15, 2005

John Larkin wrote...

John Larkin wrote:

Still checking this board. Tedious. It reports a jillion clearance
errors at 8/8 design rules, just from all the pins on the US8 parts.

No, it's this nasty little thing. Hard to solder, darn near impossible
to probe: http://www.fairchildsemi.com/products/logic/pdf/mab08a.pdf

Why's that any worse than any other 0.5mm plastic flat-package part?
Not the smallest part around, pins on top, away from package, some
room under the package, pins can be inspected...

What's painful is ICs using these small dimensions, but requiring a
thermal/electrical solder connection to a pad underneath, like Analog
Devices' new DDS chips, which have a 2mm square pad. We're using the
ad9953, just finishing a PCB, and I'm not sure how to deal with it.
See page 30, http://www.analog.com/en/prod/0%2C2877%2CAD9953%2C00.html
and http://www.analog.com/UploadedFiles/Packages/231465055SV_48_1.pdf

--
Thanks,
- Win

Jeff L · Aug 15, 2005

"Winfield Hill" <Winfield_member@newsguy.com> wrote in message
news:ddopl801e1u@drn.newsguy.com...

John Larkin wrote...

John Larkin wrote:

Still checking this board. Tedious. It reports a jillion clearance
errors at 8/8 design rules, just from all the pins on the US8 parts.

No, it's this nasty little thing. Hard to solder, darn near impossible
to probe: http://www.fairchildsemi.com/products/logic/pdf/mab08a.pdf

Why's that any worse than any other 0.5mm plastic flat-package part?
Not the smallest part around, pins on top, away from package, some
room under the package, pins can be inspected...

What's painful is ICs using these small dimensions, but requiring a
thermal/electrical solder connection to a pad underneath, like Analog
Devices' new DDS chips, which have a 2mm square pad. We're using the
ad9953, just finishing a PCB, and I'm not sure how to deal with it.
See page 30, http://www.analog.com/en/prod/0%2C2877%2CAD9953%2C00.html
and http://www.analog.com/UploadedFiles/Packages/231465055SV_48_1.pdf

--
Thanks,
- Win

The proper way to deal with them is with paste and hot air. Then they are
not so bad. For prototype quantities, some people put a giant via under the
pad, so that they can solder it from the back side with a iron. If you want
to have some fun, try some QFN's, or DFN's (same idea as the IC your using,
only no leads out the side, they are flush to the package, stuck around the
big pad in the middle, on the bottom!). They are, however, not too bad
_once_ you get used to them. Or how about CSP's - some are 0.8 mm square
with 8 or 9 solder bumps on the bottom - i.e. an 800 um BGA!

Jeff

Tim Shoppa · Aug 15, 2005

like Analog Devices' new DDS chips, which have
a 2mm square pad. We're using the ad9953, just
finishing a PCB, and I'm not sure how to deal with it.

Three words of advice:

1. The pad isn't really 2mm by 2mm. It's bigger. Yeah, the data
sheet shows 2mm by 2mm, but do not route any traces/vias for 4x4mm
or so around the center.

2. Just put a square via with a 1.5mm or 2mm or so hole underneath the
part and solder through the via. I'm not sure exactly what hole size I
used but choose something big enough to get the point of your not-
skinniest solering iron through.

3. The AD995x do not run hot at all if you keep to under 400MHz.
There are some experimenters running them at 800MHz plus, but
I can't figure out why other than to make heat!

4. Split the A and D ground planes like they advise, tie them together
where you've got the big bypass C.

5. Some of the AD datasheet/app notes show the PLL filter cap to be
0.01uF, others show 0.1uF. The small part is chosen entirely to make
the PLL lock fast after recovery from sleep. Use the big part in all
other circumstances.

OK, that was 5. (Nobody expects the spanish inquisition! We have
three weapons at our disposal...)

This chip is fun and even a complete noob like me managed to
use it. I even had two of my little kids running around in the
basement
while I hand-soldered it.

Tim.

Winfield Hill · Aug 15, 2005

Jeff L wrote...

Winfield Hill wrote ...

What's painful is ICs using these small dimensions, but requiring a
thermal/electrical solder connection to a pad underneath, like Analog
Devices' new DDS chips, which have a 2mm square pad. We're using the
ad9953, just finishing a PCB, and I'm not sure how to deal with it.
See page 30, http://www.analog.com/en/prod/0%2C2877%2CAD9953%2C00.html
and http://www.analog.com/UploadedFiles/Packages/231465055SV_48_1.pdf

The proper way to deal with them is with paste and hot air. Then they
are not so bad.

In a full automated production environment. We have a hot-air system
with preheat under, that we use for prototypes. But I don't know how
much paste to put down under the IC, etc. I assume all the solder
has to be melted at once to avoid stress after the part cools down.

For prototype quantities, some people put a giant via under the pad,
so that they can solder it from the back side with a iron.

This is after soldering the 0.5mm pins, right? When soldering to
the middle pad through the via, how can one avoid permanent thermal
stress after the part cools?

If you want to have some fun, try some QFN's, or DFN's (same idea as
the IC your using, only no leads out the side, they are flush to the
package, stuck around the big pad in the middle, on the bottom!).
They are, however, not too bad _once_ you get used to them. Or how
about CSP's - some are 0.8 mm square with 8 or 9 solder bumps on
the bottom - i.e. an 800 um BGA!

We haven't had too much trouble with these, hold in place, hot air
directly on top, until they suddenly settle down onto the pcb.

--
Thanks,
- Win

PeteS · Aug 15, 2005

Although I haven't used the device you have there, I have been using
TIs parts with the equivalent (they call it PowerPad).

There's an excellent application note at:
http://focus.ti.com/lit/an/slma002/slma002.pdf

Cheers

PeteS

Winfield Hill · Aug 15, 2005

PeteS wrote...

Although I haven't used the device you have there, I have been
using TIs parts with the equivalent (they call it PowerPad).

There's an excellent application note at:
http://focus.ti.com/lit/an/slma002/slma002.pdf

Thanks, Pete, Analog Devices seems to have little to say about
the subject, that I could see in 15-minutes of searching anyway.
I was getting ready to search TI, ST, LTC and Fairchild, etc.,
next, and you saved me the time! That's a very useful app note.

--
Thanks,
- Win

Jeff L · Aug 15, 2005

"Winfield Hill" <Winfield_member@newsguy.com> wrote in message
news:ddprm60ugj@drn.newsguy.com...

Jeff L wrote...

Winfield Hill wrote ...

What's painful is ICs using these small dimensions, but requiring a
thermal/electrical solder connection to a pad underneath, like Analog
Devices' new DDS chips, which have a 2mm square pad. We're using the
ad9953, just finishing a PCB, and I'm not sure how to deal with it.
See page 30, http://www.analog.com/en/prod/0%2C2877%2CAD9953%2C00.html
and http://www.analog.com/UploadedFiles/Packages/231465055SV_48_1.pdf

The proper way to deal with them is with paste and hot air. Then they
are not so bad.

In a full automated production environment. We have a hot-air system
with preheat under, that we use for prototypes. But I don't know how
much paste to put down under the IC, etc.

Put a little dab of paste on the center pad (not too much or you will have
to remove some, since the IC will not sit low enough for the pins to touch -
push down on the IC, during reflow and a big solder ball should pop out if
that happens), place the part, reflow it using hot air, and make sure it's
centered on the pads using tweezers. When cool, solder the pins by hand.
Thermal stresses should be less with this type of part, when hand soldering,
since you now have the big pad sucking heat away from the die. The legs
basically have a stretched Z shaped bend to absorb different thermal
expansions. If it still bothers you, you can reflow it again after soldering
the pins to relive any stresses.

I assume all the solder
has to be melted at once to avoid stress after the part cools down.

For prototype quantities, some people put a giant via under the pad,
so that they can solder it from the back side with a iron.

This is after soldering the 0.5mm pins, right?

Exactly

When soldering to
the middle pad through the via, how can one avoid permanent thermal
stress after the part cools?

See above. You loose a little heat sinking ability if the center pad is not
soldered first, but the large chunk of copper can keep it significantly
cooler then a similar TSSOP without the copper pad, whose pins would be
soldered the same way.

If you want to have some fun, try some QFN's, or DFN's (same idea as
the IC your using, only no leads out the side, they are flush to the
package, stuck around the big pad in the middle, on the bottom!).
They are, however, not too bad _once_ you get used to them. Or how
about CSP's - some are 0.8 mm square with 8 or 9 solder bumps on
the bottom - i.e. an 800 um BGA!

We haven't had too much trouble with these, hold in place, hot air
directly on top, until they suddenly settle down onto the pcb.

--
Thanks,
- Win

qrk · Aug 16, 2005

On 15 Aug 2005 08:11:20 -0700, "PeteS" <ps@fleetwoodmobile.com> wrote:

Although I haven't used the device you have there, I have been using
TIs parts with the equivalent (they call it PowerPad).

There's an excellent application note at:
http://focus.ti.com/lit/an/slma002/slma002.pdf

Cheers

PeteS

One thing that I haven't been able to find (haven't looked in the past
6 months) for QFN packages is the recommended solder paste stencil
area for the die attach (paddle) pad. Linear Technology sent me the
Carsem MLP Application note which, again, sidesteps the solder paste
stencil area for the die attach pad. I have found that making the
solder paste stencil area 70% of the die attach pad area has prevented
the part from "floating" and causing shorts from pads to die attach
area. I also use a checkerboard pattern as recommended in the Carsem
application note.

http://www.carsem.com/services/Drwgs&Data/CSM-MLP%20apps%20note-4-23-2002-300dpi.pdf

---
Mark

qrk · Aug 16, 2005

On Sun, 14 Aug 2005 16:55:04 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Sun, 14 Aug 2005 19:55:37 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

[snip]

US8. The recommended footprint has 0.3 mm pads on 0.5mm spacing, so
the clearance is 0.2mm (an RCH under 8 mils).

Best regards,
Spehro Pefhany

I dated a red-head in high school just to check that out ;-)

...Jim Thompson

Did you get a measurement?

---
Mark

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