PCB Design Software

[Andy Peters]

Active8 <mTHISREMOVEcolasono@earthlink.net,invalid> wrote in message news:<MPG.1a5983ed94d0b8f3989787@news.west.earthlink.net>...

One of the most important features of an EDA tool is the components
library. A good library makes everyone's life easier.

I prefer good looking librarians.

Yeah, that makes you want to ask them for help.

The idea is that the every component in the library has all of the
information needed to build a board.

Nope. Just that little piece of real estate within the place and/or
insertion outline, whichever is greater. Design rules dictate what
other objects can get inside or near that area. It also won't
specify plating type, thickness, or hole tolerance. Just Drill
size, pad dimensions, plated or non, electrical or non, silkscreen,
soldermask, assembly view, various text like reference, component,
and footprint... assembly view artwork, power plane clearance.
Place and insertion outline. Drill symbol. Orientation/place datum.
Lotta stuff for a part.

OK, that's just PCB layout. If you're building PCAs, you need to
order parts to put on the board!

When you place a symbol on the
schematic, that component will also have footprint info (for PCB
layout),

Only if the part was designed with default footprint name. You can
add or change it or make 2 identical parts with diff FPs so you
don't have to remember the LIB name.

What, your tools don't have library browsers?

manufacturer part numbers (if your tools can spit out
bills-of-materials, which it damn well should!), perhaps even links to
spice models, Verilog sources, etc. The idea is that you do all of
that work upfront building your library.

Or download or buy a library if what you have sucks or is
incomplete.

Download/buy a footprint library, or download/buy a "component
library"? I'm advocating the latter.

Consider a tool that has a footprint library, a symbol library, and a
"component libary" that marries the two. Say you have cheeseball quad
op-amps in your library: a TL074_SO is the SOIC version, and the
TL074_DIP is the DIP version. When you draw the schematic, place the
specific part you want, and all the info is there. No editing of
property fields (easily forgotten) needed.

A good library will have a component for each and every
resistor/capacitor/etc.
Why? Because each part contains the part
number you use to order it, and the package info.

*Do* they, now?

Yep,

Oh. So I need a separate part for the 20 different 10k resistors I
use, each with a special name so I know which part I'm selecting
into the schem?

Well, if you want to avoid having your purchasing person pester you
with questions like, "What's the part number?" And if you want the
PCB layout person to know the footprint without having to ask you.
Again: think *component* library, not just symbol library and
footprint library.

because it's real easy to take a
generic resistor out of the generic library and modify its "value"
field, but at some point, you've got to make the PCB, and the PCB guy
needs to know if you want a through-hole 5% 10K resistor, or an 0805
1%, or whatever.

The PCB house doesn't care about component tolerance, a prototype
house does. Gerbers and drill files, mainly. Plating instructions
or take their default.

Yeah, but the PCB is only part of the design.

And, of course, the purchasing people need to have
an orderable part number.

That's still in production and not just collecting dust in the mfgs
catalog, muRata.

That's a different problem

I have a special partnum property field

So, you place a TL074 on your schematic, and then edit the partnum
field of that instance? And also edit the footprint field, too?

otherwise, I'd just
run the BOM and import it into excel where you can hand it off to a
serving wench to look up the numbers I had a gal at Newark who
would look up her nums for stuff like 74HC00 or 1N4004 and ask
which mfg and suffix and look up the suffixes meanings. Jenny.
Gone, AFAIK. A real gem. Made my life easier.

So, what do you do now that Jenny's not making your life easier?

This may be redundant, but i wrote this first. TFB

Eagle is PCB only. With a suite, you set the footprint properties
in the schematic capture program or if you just want to do a board,
you place the footprint as a component.

Ah, Eagle. That explains things. It's kinda hard going from Mentor,
or even PCAD, to Eagle.

But just having a good footprint library doesn't mean you can just
go from BOM to ordering.

Exactly my point.

My libraries have pathname-like names and
there is no "SOIC" per se. and there's other numbers in the name
like the width and length of the package which is important for
placement and insertion.

Right -- you could give the footprints the same names that TI gives
'em, or whatever. As long as you know which one is which.

Manufacturers and distributors use a suffix like SO for SOIC or ML
for QFN.

G-d forbid that there'd be a standard for package suffixes!

Really, tho', you should work whichever way works for you. I prefer
having to look up part numbers once.

--a

 

[Active8]

On 29 Dec 2003 08:12:31 -0800, Bassman59a@yahoo.com said...

Active8 <mTHISREMOVEcolasono@earthlink.net,invalid> wrote in message news:<MPG.1a5983ed94d0b8f3989787@news.west.earthlink.net>...
One of the most important features of an EDA tool is the components
library. A good library makes everyone's life easier.

I prefer good looking librarians.

Yeah, that makes you want to ask them for help.


The idea is that the every component in the library has all of the
information needed to build a board.

Nope. Just that little piece of real estate within the place and/or
insertion outline, whichever is greater. Design rules dictate what
other objects can get inside or near that area. It also won't
specify plating type, thickness, or hole tolerance. Just Drill
size, pad dimensions, plated or non, electrical or non, silkscreen,
soldermask, assembly view, various text like reference, component,
and footprint... assembly view artwork, power plane clearance.
Place and insertion outline. Drill symbol. Orientation/place datum.
Lotta stuff for a part.

OK, that's just PCB layout. If you're building PCAs, you need to
order parts to put on the board!

When you place a symbol on the
schematic, that component will also have footprint info (for PCB
layout),

Only if the part was designed with default footprint name. You can
add or change it or make 2 identical parts with diff FPs so you
don't have to remember the LIB name.

What, your tools don't have library browsers?

Yeah, but there's a lot of footprints with just slightly different
and very long names and onece you find those 2 out of many...

manufacturer part numbers (if your tools can spit out
bills-of-materials, which it damn well should!), perhaps even links to
spice models, Verilog sources, etc. The idea is that you do all of
that work upfront building your library.

Or download or buy a library if what you have sucks or is
incomplete.

Download/buy a footprint library, or download/buy a "component
library"? I'm advocating the latter.

That would be ideal and is most likely what I've seen while
searching. Didn't see much that would help out with the cheaper
CADs like CM or EWB and of course Eagle is PCB, so there's no
component lib.

Consider a tool that has a footprint library, a symbol library, and a
"component libary" that marries the two. Say you have cheeseball quad
op-amps in your library: a TL074_SO is the SOIC version, and the
TL074_DIP is the DIP version. When you draw the schematic, place the
specific part you want, and all the info is there. No editing of
property fields (easily forgotten) needed.

In Orcad, that would be the value field and the partnum and
footprint fields are still blank, but you can edit the part and
store it in your own library with all that extra info preassigned.

A good library will have a component for each and every
resistor/capacitor/etc.
Why? Because each part contains the part
number you use to order it, and the package info.

*Do* they, now?

Yep,

Oh. So I need a separate part for the 20 different 10k resistors I
use, each with a special name so I know which part I'm selecting
into the schem?

Well, if you want to avoid having your purchasing person pester you
with questions like, "What's the part number?" And if you want the
PCB layout person to know the footprint without having to ask you.
Again: think *component* library, not just symbol library and
footprint library.

the part num on a 10k and 5k would be

151-103 and 151-102 from one source and something else from another
source, so putting 151-xxx in the partnum field has limited use for
say, a 10k 5% 1/4W axial lead. remember, "value" is 10k so
reference designator, which is what you're selectin, i.e., what's
visible in the parts browser would have to be.

R_5_.25_AX
R_5_.25_0603
R_5_.125_AX
R_5_.125_0603

each with partnum 15x-xxx or whatever. I like to just grab a
resistor symbol and place as many as I need, select them all,
assign values and other properties, and drag them where they go.
Assembly line fashion - one step at a time - if I can.

because it's real easy to take a
generic resistor out of the generic library and modify its "value"
field, but at some point, you've got to make the PCB, and the PCB guy
needs to know if you want a through-hole 5% 10K resistor, or an 0805
1%, or whatever.

The PCB house doesn't care about component tolerance, a prototype
house does. Gerbers and drill files, mainly. Plating instructions
or take their default.

Yeah, but the PCB is only part of the design.

And, of course, the purchasing people need to have
an orderable part number.

That's still in production and not just collecting dust in the mfgs
catalog, muRata.

That's a different problem

Don't I know it.

I have a special partnum property field

So, you place a TL074 on your schematic, and then edit the partnum
field of that instance? And also edit the footprint field, too?

Yup, some parts have default info that works, but I still check it.

otherwise, I'd just
run the BOM and import it into excel where you can hand it off to a
serving wench to look up the numbers I had a gal at Newark who
would look up her nums for stuff like 74HC00 or 1N4004 and ask
which mfg and suffix and look up the suffixes meanings. Jenny.
Gone, AFAIK. A real gem. Made my life easier.

So, what do you do now that Jenny's not making your life easier?

I've roughing it. Using the web catalogs. Hoping to get to the
point where I can justify full-time help.

After writing the above about Jenny, I think from now on, I'm just
going to start sending the BOM out to everyone and sundry and let
them look up the partnums and fill in the prices Isn't that a
sales droid's job?

Dear droid:
Please see how many of these parts you can source and fill in the
prices and part numbers. Your competitors are racing to beat you to
the punch.

This may be redundant, but i wrote this first. TFB

Eagle is PCB only. With a suite, you set the footprint properties
in the schematic capture program or if you just want to do a board,
you place the footprint as a component.

Ah, Eagle. That explains things. It's kinda hard going from Mentor,
or even PCAD, to Eagle.

I don't think they enjoy some of the flexibility you're used to.

But just having a good footprint library doesn't mean you can just
go from BOM to ordering.

Exactly my point.

My libraries have pathname-like names and
there is no "SOIC" per se. and there's other numbers in the name
like the width and length of the package which is important for
placement and insertion.

Right -- you could give the footprints the same names that TI gives
'em, or whatever. As long as you know which one is which.


Manufacturers and distributors use a suffix like SO for SOIC or ML
for QFN.

G-d forbid that there'd be a standard for package suffixes!

No kidding.

Really, tho', you should work whichever way works for you. I prefer
having to look up part numbers once.

I keep spreadsheets on different sources Until' the part number
changes... That happened with Newark, IIRC. I kinda remember Jenny
commenting about the new system (complete overhaul) being funny.
But she seemed to manage to adapt easily. Resitance is futile

I guess I could use VBA to take the BOM spreadsheet and merge them
with the supplier spreadsheets. Another piece of code.

Orcad has CIS or component Information System which I'm not
familiar with, but It allows you to select parts from your own
database and I think that's basically what you're talking about. I
forgot about that and that *is* a practical solution.

Jim Thomson will gag when I say this, but though I haven't played
with Protel (and lost respect for the whole CM, Protel, Altium
clusterf&&K) I recommend Orcad based on what can be done with it
even though the documentation is crap at best. If price is a factor
and the student version doesn't cut it (I can get away with
simulating very small functional blocks and combining them later) I
recommend using SuperSpice and LtSpice in combination. The problem
is no board layout facility. I like to go from schematic to layout
and have the ratsnest there to help me place and route.

But Terry Pinnel has a CAD review page and others have their own
opinions, so anyone searching has enough resources right here to
make an informed decision.

--
Best Regards,
Mike

 

[Gary A. Crowell Sr.]

On 29 Dec 2003 08:12:31 -0800, Bassman59a@yahoo.com (Andy Peters) wrote:

G-d forbid that there'd be a standard for package suffixes!

While not a 'suffix' per se, the "IPC-7351 Library Part Naming Convention" isn't
bad. I'm trying to use it for naming all my parts now. Wish the manufacturers
would use it.

Downloadable from: http://www.pcblibraries.com/downloads/_GEN-docs.asp

If you have, or can convert from, PADS, they have a complete 7351 library
downloadable there too.

Gary Crowell
Micron Technology
(__ (__ (_____ (______ TM
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(__ (__ (__ (________ V1.64
(__ (__ (__ (__
(_____ (____ (__ (__ Freeware CP/CG Calculator
(____ (______ (__ (c)1996 Gary A. Crowell Sr.
vcp@cableone.net
http://myweb.cableone.net/cjcrowell