I'd suggest using JEDEC and EIAJ standards. The majority of manufacturer's
packages can be mapped to one of the standardised designs. Some
manufacturers
will actually state that a package meets a JEDEC/EIAJ design, while others
have
packages that have tighter tolerances than the respective JEDEC/EIAJ design,
but for which the JEDEC/EIAJ footprint works.

for example, a SOT23-5 maps to JEDEC MO-178-AA

A TSSOP-14 might map to MO-153-AB-1 (e.g. for TI parts) but the same TSSOP
moniker
might also apply to an EIAJ standard instead (e.g. EIAJ_TSSOP14-P-0044-0.65)
Using the common TSSOP-14 descriptor can therefore point to an incorrect
footprint, while explicitly stating the standard prevents errors (although,
of course, there is then effort required in figuring out that the Analog
Devices'
SOIC-28 package type RS-28 maps to a JEDEC MO-150-AH, for example).

Of course, this all falls in a screaming heap when there is no matching
standard,
such as is found with new packages like uBGAs and CSPs

Back to the topic at hand:

I'd use the dimensions which are commonly quoted in the packaging standards,
since
manufacturers are progressively moving to the same standards of drawings.

Just my $0.02c

John Haddy


> -----Original Message-----
> From: Brian Guralnick [mailto:[EMAIL PROTECTED]]
> Sent: Friday, 27 July 2001 2:20 AM
> To: Protel EDA Forum
> Subject: [PEDA] ClientBasic footprint generator.
>
>
> That's it,  I will now make a ClientBasic program which will
> create perfect footprints based on the measurements which are actually
> in the data sheets.  It will create dual & quad flat packs.
>
> I need to know who's IC package data sheets would be best to work
> with as reference.
>
> Does ClientBasic pass metric into Protel, or do I have to
> calculate the entries to imperial?
>
> ____________
> Brian Guralnick
>
>
>

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