Under no circumstances should the Protel libraries be copied! They
are riddled with errors (I'd list them all as "unverified"). For
instance, any metric pitch component that's been created with the
footprint wizard is likely to be wrong.
The biggest hurdle I forsee is the widely differing requirements
of any single footprint. For example: a footprint for wave solder
is different from that for reflow; the IPC "worst-case" design
methodology generates overly conservative footprints; a designer
working on high density layouts will want "bleeding edge" land
pattern designs, not general purpose ones with excessive silkscreen
clearances (for example). So just with these few variations, we're
up to at least four variants of every footprint!
Much as I applaud the sentiment, I can't see a single library ever
providing a single source set of footprints.
I regularly use components that have land pattern designs tailored
to the manufacturing process; e.g. I might create an SC70-6 footprint
which is fine for the current project because I'll be using a
0.004" paste stencil thickness, however the same design may well cause
manufacturing issues if it's used with a 0.006" paste stencil!
We're going to need much more sophisticated design rules before I'd
consider using anybody else's designs (so that I can check, for
example, paste aperture ratios given a specified screen thickness)
Just my $0.02
John Haddy
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, 25 July 2001 12:03 PM
> To: Protel EDA Forum
> Subject: Re: [PEDA] a lib. for everyone
>
>
>
>
> Im assuming that the existing PCB footprint libraries on the
> Protel website
> would be a subset of this super library.
> The libraries are:
>
> BGA 531 footprints in 9 libraries based on pin pitch
> Through Hole 107 footprints in 5 libraries
> QFP's 226 footprints in 12 libraries based on pin
> pitch and
> index position (with duplicated footprints)
> Chip carrier 74 footprints in 2 libraries
> SOP 129 footprints in 2 libraries
>
> Plus a number of manufacturer specific and general libraries.
> Taking just the
> semiconductor footprints, thats
> 1067 footprints that will be bundled into the super library that
> someone will be
> remaking. Or will these footprints
> just be copied from the existing Protel libraries? If these
> seperate libraries
> get jumbled into one library, will
> it make using and finding easier? Who will be doing the work on this?
>
>
>
> _______________________________________________________________
>
> Clive Broome
> IDT Sydney Design Centre Ph: +61 2 9763 3513
> 8 Bayswater Dr, Homebush Fax: +61 2 9763 3409
> Sydney, NSW, 2127 Email:[EMAIL PROTECTED]
> Australia
>
> Australia's Leading Semiconductor Designers
> ---------------------------------------------------------------
>
>
>
>
>
>
>
>
> "Ted Tontis" <[EMAIL PROTECTED]> on 07/24/2001 04:50:18 AM
>
> Please respond to "Protel EDA Forum" <[EMAIL PROTECTED]>
>
> To: "Protel Forum (E-mail)" <[EMAIL PROTECTED]>
> cc: (bcc: Clive Broome/sdc)
>
> Subject: [PEDA] a lib. for everyone
>
>
>
> Would there be any interest in a PCB footprint lib. with all the parts you
> would ever need for free. I ask this because I am working on
> trying to get a
> large lib. in Protel. It would have the silk screen, a fence that would be
> on the last electrical layer to avoid component placement conflictions,
> assembly art work, pin 1 id. All parts would be in mm I welcome any input
> towards this idea weather it be good or bad.
>
> Ted Tontis C.I.D.
> Engage Networks
> 316 N. Milwaukee Street
> Suite 214
> Milwaukee WI, 53202
> PH 414-273-7600 ext. 7607
> FX 414-273-7601
>
>
>
>
>
>
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