Re: gEDA-user: finding shorts with gschem

[David Griffith]

On Sat, 2 Feb 2008, John Griessen wrote:

> David Griffith wrote:
>   I found that Vdd got connected to Vcc sometime during the
> > schematic entry.  Short of poring over the entire schematic, how can I
> > find where this happens?
>
> You can cut apart nets and rerun gnetlist if you must stay in graphical
> mode...errr no, there's no higlightin in gschem yet, so you can't stsy
> in graphical mode.
>
> You can just read the netlist and search for your power or ground and
> see all the nets it is included in.
>
> You will quickly come to a jump to another net besides the one with
> Vdd's that belong.. To tell what belongs is by seeing a few chip power
> pins in one group -- that becomes your "correct" Vdd.

I think I uncovered a subtle bug.  I replaced Vdd, Vee, and Vcc with +8V,
-8V, and +5V respectively and the problem disappeared.  I can't seem to
come up with a simple test case though.


-- 
David Griffith
[EMAIL PROTECTED]

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?


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Re: gEDA-user: finding shorts with gschem

[John Griessen]

David Griffith wrote:
  I found that Vdd got connected to Vcc sometime during the
> schematic entry.  Short of poring over the entire schematic, how can I
> find where this happens?

You can cut apart nets and rerun gnetlist if you must stay in graphical 
mode...errr no,
there's no higlightin in gschem yet, so you can't stsy in graphical mode.

You can just read the netlist and search for your power or ground and see all 
the nets it is included in.

You will quickly come to a jump to another net besides the one with Vdd's that 
belong..
To tell what belongs is by seeing a few chip power pins in one group -- that 
becomes your "correct" Vdd.

John Grieseen


-- 
Ecosensory   Austin TX


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gEDA-user: attributes net and refdes, subdesigns, power and ground?

[Britton Kerin]

I have a design with two subcircuits.  I pretty much copied the gTAG
example but I missed the trick of making a netname=foo wire in the
toplevel and then putting an input or output with refdes=foo in the
subdesigns, so my +3.3V isn't continuous through my board as intended.

The odd thing is that my ground isn't continuous either, and it didn't
look as if the gTAG is doing anything special about this?

Britton




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Re: gEDA-user: Design with a 144 pin QFP

[Ben Jackson]

On Sat, Feb 02, 2008 at 12:09:37PM +, ST de Feber wrote:
> 
> Has any one of you designed a PCB with a 144 pin
> QFP/TQFP package ? (with or without exposed die pad)

I just made a board with a QFP208 (0.5mm), 100 (0.65mm rectangular) and
80 (0.65mm square).

> How many layers will such a board have ?

It depends entirely on the function of the chips.  If it's a digital chip
and only uses a single power supply you might be able to use just two
layers.  If it's fast digital and/or analog and has multiple supplies
you will probably need at least 4 layers.  If it's an FPGA you can simplify
your routing because most of the pins are interchangable.  If it's a
CPU you might need more layers to get the connections to the right places.
I probably could not have routed my two SRAM chips on less than 4 layers
(just too many power and ground pins plus the need to bus together the
A and D lines) but if I'd only used one, larger SRAM I might have gotten
away with 2.

-- 
Ben Jackson AD7GD
<[EMAIL PROTECTED]>
http://www.ben.com/


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Re: gEDA-user: gnucap warning

[al davis]

On Saturday 02 February 2008, Robert Butts wrote:
> Seriously, why the warning?

To make it legal in California.



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Re: gEDA-user: Anybody had luck with QFN64 at PCBExpress et al?

[Steven Michalske]

I used rounded and square pads on my QFN designs,  The boards were
made at Sierra proto express.  They may not be the cheapest,  but they
can do bards with 1 mil traces.

I did not have the boards assembled, I hand soldered them,  not on a
hot plate or other oven like methods.

Drag soldering the QFN is not a difficult process,  it just takes a
bit of time to line up the pins to the pads 2 dimensionally.  solder
paste probably would have helped.

The thermal pad on the backs of QFN and friends, I put in one or two
untented vias, they serve two purposes, I can now hand solder through
them, and they thermally connect the thermal pad to the copper on the
opposite side.


Best of luck on you boards!

Steve

On Feb 2, 2008 11:55 AM, Jeffrey Baker <[EMAIL PROTECTED]> wrote:
> On Feb 2, 2008 11:41 AM, joe tarantino <[EMAIL PROTECTED]> wrote:
>
> >
> >
> >
> >
> >
> >
> > On Feb 2, 2008 11:23 AM, Jeffrey Baker <[EMAIL PROTECTED]> wrote:
> >
> > >
> > >
> > >
> > > Nearly every major part I need for my latest project is packaged in a
> QFN (or LFCSP as they call it over at Analog Devices).  I'm worried because
> the parts have round leads and Sunstone, the PCB prototype shop, says they
> can't make radiused SMD pads.  Has anyone run into trouble with this, or are
> square pads OK?
> > >
> > > Generally speaking the .5mm-pitch QFN seems to be on the edge of or
> beyond the capabilities of a proto shop like Sunstone, but Sunstone has the
> best tolerances I've been able to find.
> > >
> >
>
> >
> >
> > >
> > >
> > >
> > >
> >
> >
> > I have had one of the Sunstone shops build boards with QFN32 and QFN48 as
> I recall.  Results were pretty good.  They had square-ended pads.
>
>
> DId you draw them that way, or did you draw them rounded?
>
>
> >
> >
> >
> > -Be careful of solder resist "floaters" due to the little pieces between
> the leads.  Best bet is to remove all resist between pads.
>
> Interesting.  Manufacturers seem to disagree on this point.  Freescale says
> remove solder mask between pins.  Intersil says keep it.  Sunstone can do
> .005" solder mask web so it's just barely possible to have it either way.
> You don't worry about solder bridges without solder mask?
>
> >
> >
> >
> > -You may want to check your gerber files to see how much solder paste will
> be applied and check with Sunstone to see if it is sufficient (or too much).
> >
> > Does your pad have a large heat sink pad on the back?  If so, you must
> carefully construct this pad in the footprint (possibly out of multiple
> squares).  Again, check the paste layer.
> >
>
> Oh yes, the dreaded exposed pad.  I appreciate the thermal properties of
> this package.  However I find drawing it to be a huge nuisance.  I drew the
> stencil layer with an array of rectangles of the same size as the SMD pads
> (.30mmx.65mm) separated by .13mm.  It seems like that should give a decent
> coverage without leaving the part high-centered.
>
> Thanks for the tips!
>
>
>
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gEDA-user: finding shorts with gschem

[David Griffith]

I've finished entering a schematic and have started laying out the foil
with pcb.  I found that Vdd got connected to Vcc sometime during the
schematic entry.  Short of poring over the entire schematic, how can I
find where this happens?

-- 
David Griffith
[EMAIL PROTECTED]

A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?


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Re: gEDA-user: Anybody had luck with QFN64 at PCBExpress et al?

[Jeffrey Baker]

On Feb 2, 2008 11:41 AM, joe tarantino <[EMAIL PROTECTED]> wrote:

>
>
> On Feb 2, 2008 11:23 AM, Jeffrey Baker <[EMAIL PROTECTED]> wrote:
>
> > Nearly every major part I need for my latest project is packaged in a
> > QFN (or LFCSP as they call it over at Analog Devices).  I'm worried because
> > the parts have round leads and Sunstone, the PCB prototype shop, says they
> > can't make radiused SMD pads.  Has anyone run into trouble with this, or are
> > square pads OK?
> >
> > Generally speaking the .5mm-pitch QFN seems to be on the edge of or
> > beyond the capabilities of a proto shop like Sunstone, but Sunstone has the
> > best tolerances I've been able to find.
> >
>

>
> > I have had one of the Sunstone shops build boards with QFN32 and QFN48
> as I recall.  Results were pretty good.  They had square-ended pads.
>

DId you draw them that way, or did you draw them rounded?


>
> -Be careful of solder resist "floaters" due to the little pieces between
> the leads.  Best bet is to remove all resist between pads.
>

Interesting.  Manufacturers seem to disagree on this point.  Freescale says
remove solder mask between pins.  Intersil says keep it.  Sunstone can do
.005" solder mask web so it's just barely possible to have it either way.
You don't worry about solder bridges without solder mask?


>
> -You may want to check your gerber files to see how much solder paste will
> be applied and check with Sunstone to see if it is sufficient (or too much).
>
> Does your pad have a large heat sink pad on the back?  If so, you must
> carefully construct this pad in the footprint (possibly out of multiple
> squares).  Again, check the paste layer.
>

Oh yes, the dreaded exposed pad.  I appreciate the thermal properties of
this package.  However I find drawing it to be a huge nuisance.  I drew the
stencil layer with an array of rectangles of the same size as the SMD pads
(.30mmx.65mm) separated by .13mm.  It seems like that should give a decent
coverage without leaving the part high-centered.

Thanks for the tips!


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Re: gEDA-user: Anybody had luck with QFN64 at PCBExpress et al?

[Steve Meier]

The shop I use insists that the solder mask features must be at least 5
mills wide other wise you should gang unmask the pads.

Steve Meier

joe tarantino wrote:
>
>
> On Feb 2, 2008 11:23 AM, Jeffrey Baker <[EMAIL PROTECTED]
> > wrote:
>
> Nearly every major part I need for my latest project is packaged
> in a QFN (or LFCSP as they call it over at Analog Devices).  I'm
> worried because the parts have round leads and Sunstone, the PCB
> prototype shop, says they can't make radiused SMD pads.  Has
> anyone run into trouble with this, or are square pads OK?
>
> Generally speaking the .5mm-pitch QFN seems to be on the edge of
> or beyond the capabilities of a proto shop like Sunstone, but
> Sunstone has the best tolerances I've been able to find.
>
> -jwb
>
>
>
> ___
> geda-user mailing list
> geda-user@moria.seul.org 
> http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
>
>
> I have had one of the Sunstone shops build boards with QFN32 and QFN48
> as I recall.  Results were pretty good.  They had square-ended pads.
>
> -Be careful of solder resist "floaters" due to the little pieces
> between the leads.  Best bet is to remove all resist between pads.
> -You may want to check your gerber files to see how much solder paste
> will be applied and check with Sunstone to see if it is sufficient (or
> too much).
>
> Does your pad have a large heat sink pad on the back?  If so, you must
> carefully construct this pad in the footprint (possibly out of
> multiple squares).  Again, check the paste layer.
>
> Joe T
>
> 
>
>
>
> ___
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>   



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Re: gEDA-user: Anybody had luck with QFN64 at PCBExpress et al?

[joe tarantino]

On Feb 2, 2008 11:23 AM, Jeffrey Baker <[EMAIL PROTECTED]> wrote:

> Nearly every major part I need for my latest project is packaged in a QFN
> (or LFCSP as they call it over at Analog Devices).  I'm worried because the
> parts have round leads and Sunstone, the PCB prototype shop, says they can't
> make radiused SMD pads.  Has anyone run into trouble with this, or are
> square pads OK?
>
> Generally speaking the .5mm-pitch QFN seems to be on the edge of or beyond
> the capabilities of a proto shop like Sunstone, but Sunstone has the best
> tolerances I've been able to find.
>
> -jwb
>
>
>
> ___
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> geda-user@moria.seul.org
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>

I have had one of the Sunstone shops build boards with QFN32 and QFN48 as I
recall.  Results were pretty good.  They had square-ended pads.

-Be careful of solder resist "floaters" due to the little pieces between the
leads.  Best bet is to remove all resist between pads.
-You may want to check your gerber files to see how much solder paste will
be applied and check with Sunstone to see if it is sufficient (or too much).

Does your pad have a large heat sink pad on the back?  If so, you must
carefully construct this pad in the footprint (possibly out of multiple
squares).  Again, check the paste layer.

Joe T


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Re: gEDA-user: gnucap warning

[Robert Butts]

Seriously, why the warning?

On Feb 2, 2008 2:09 PM, Steve Meier <[EMAIL PROTECTED]> wrote:

> If it a microsoft application it won't even function until at least 3.1
>
> al davis wrote:
> > On Saturday 02 February 2008, Robert Butts wrote:
> >
> >> Never trust any version less than 1.0
> >>
> >
> > If you design a new chip, and spend $10 million to get it made,
> > and it doesn't sell ...  It's not my fault.
> >
> >
> > ___
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> >
> >
>
>
>
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gEDA-user: Anybody had luck with QFN64 at PCBExpress et al?

[Jeffrey Baker]

Nearly every major part I need for my latest project is packaged in a QFN
(or LFCSP as they call it over at Analog Devices).  I'm worried because the
parts have round leads and Sunstone, the PCB prototype shop, says they can't
make radiused SMD pads.  Has anyone run into trouble with this, or are
square pads OK?

Generally speaking the .5mm-pitch QFN seems to be on the edge of or beyond
the capabilities of a proto shop like Sunstone, but Sunstone has the best
tolerances I've been able to find.

-jwb


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Re: gEDA-user: gnucap warning

[Steve Meier]

If it a microsoft application it won't even function until at least 3.1

al davis wrote:
> On Saturday 02 February 2008, Robert Butts wrote:
>   
>> Never trust any version less than 1.0
>> 
>
> If you design a new chip, and spend $10 million to get it made, 
> and it doesn't sell ...  It's not my fault.
>
>
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Re: gEDA-user: gnucap warning

[al davis]

On Saturday 02 February 2008, Robert Butts wrote:
> Never trust any version less than 1.0

If you design a new chip, and spend $10 million to get it made, 
and it doesn't sell ...  It's not my fault.


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gEDA-user: gnucap warning

[Robert Butts]

I installed the gnucap that was listed in the fedora 7 package manager.  The
version is 0.35 and when I start gnucap I see this warning:

Never trust any version less than 1.0

What's up with this, do I need to update it and if so is this done with: rpm
-u?


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Re: gEDA-user: Design with a 144 pin QFP

[Dave McGuire]

On Feb 2, 2008, at 7:09 AM, ST de Feber wrote:
> Has any one of you designed a PCB with a 144 pin
> QFP/TQFP package ? (with or without exposed die pad)
>
> If so, is one of you so kind to show me the PCB files
> ?
>
> How many layers will such a board have ?
>
> Until recently i designed boards with a max of 44 (ic)
> pins. So i do not feel confident with larger packages.

   I have done a board with a 144-pin LQFP on it, double-sided.  It  
is not difficult with PCB and it won't give you any trouble.

 -Dave

-- 
Dave McGuire
Port Charlotte, FL




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Re: gEDA-user: Design with a 144 pin QFP

[Steve Meier]

Simon,

Get your confidence up 144 pin qfp is very standard.

Layers.

Maybe 3 for power and ground (Vcci, Vccio and ground)

3 for signals Top, bottom and one in the middle.

Even if you need analog then you can either add a few more layers or
carefully manage the layers that you have.

i.e if the analog section is kept distinctly seperate from the digital
then you can resuse the power and signal planes.

Just like you other boards plan your layout ahead of time.

Steve Meier

ST de Feber wrote:
> Dear all,
>
> Has any one of you designed a PCB with a 144 pin
> QFP/TQFP package ? (with or without exposed die pad)
>
> If so, is one of you so kind to show me the PCB files
> ?
>
> How many layers will such a board have ?
>
> Until recently i designed boards with a max of 44 (ic)
> pins. So i do not feel confident with larger packages.
>
> best regards
>
> Simon
>
>
>
>
>   __
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>
>
>
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Re: gEDA-user: pcb-20080202

[Levente]

On Fri, 01 Feb 2008 21:48:26 -0500
Dan McMahill <[EMAIL PROTECTED]> wrote:

> I've placed a new pcb snapshot up on sourceforge.  In addition to the 
> usual source release, there is an installer for windows.  Be warned that 
> the windows build has received very little testing.

The windows build works for me. Many thank you for this. I can now teach my
father and my girlfriend how to draw box contours. Pizza for the developers!

Cheers,

--
Levente
http://web.interware.hu/lekovacs



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gEDA-user: Design with a 144 pin QFP

[ST de Feber]

Dear all,

Has any one of you designed a PCB with a 144 pin
QFP/TQFP package ? (with or without exposed die pad)

If so, is one of you so kind to show me the PCB files
?

How many layers will such a board have ?

Until recently i designed boards with a max of 44 (ic)
pins. So i do not feel confident with larger packages.

best regards

Simon




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