excellent resource, thanks JC
i've noticed the shortness of the philips' solder land, so far no rationale
to justify it...
philips' drawing shows two different width for start/end of row/column
(0.30mm) and in between (0.23mm) for LQFP64 package, which is relevant to
this group, IPC 565A landing pattern (IPC parlance versus philips
"footprint") does not differentiate, hmmm... interesting...
The solder vaporphase reflow/IR reflow may explain our problem to obtain
chips in quantities of 10. The chip will aquire the temperature of the
solder. Presence of moisture inside the package could cause cracking of
housing. So they get shipped in dry packs containing 250 chips. The
distributor is paralyzed into no action fearing to break the drypack!
This is a hypothesis of course, anybody has one better?
j
----- Original Message -----
From: "J.C. Wren" <jcwren@...>
To: <lpc2100@yahoogroups.com>
Sent: Wednesday, February 11, 2004 10:37 PM
Subject: Re: [lpc2100] Footprint for LPC
> It's always entertaining to play "find the right footprint". The
> IPC footprint that most closely matches this is IPC-563A. The
> difference? Lands are 1.6mm x .3mm vs Philips 1.1mm x .285mm. The
> width difference isn't very significant, but the length is rather
> substantial. The typical IPC specs are for MMC or "Maximum Material
> Condition", which is basically the large end of all dimensions. LMC
> ("Least Material Condition") doesn't seem to be used much.
>
> Supposedly, IPC specs are based on real world manufacturing
> feedback, and take into account all the little details that relate to
> making a product manufacturable. That being said, I am/was using the
> IPC-563A footprint. I'd be interested in hearing the results of people
> who have had boards made using vapor phase or IR reflow and what pad
> dimensions they use.
>
> This has always been a pet peeve of mine. Some manufactures
> reference IPC standards, some JEDEC, some have thier own, and some it's
> just best guess. Given the choice, I'd prefer they adhered to IPC or
> JEDEC, AND published the spec in the datasheet. National is really good
> about this. Others are not. Referencing the IPC spec is great, but if
> you can't afford to spring for the book, you're hosed. Luckily, I found
> a copy on the web (< http://tinymicros.com/ipc >) from 1999, which has
> most everything, but does lack TSSOP specs.
>
> --jc
>
> Joseph Tapay wrote:
>
> > or make your own library entry from official philips footprint drawing
> > as i
> > am doing it
> > for LQFP48 package
> >
http://www.semiconductors.philips.com/acrobat/packages/footprint/FOOTPRINT-HTQFP-HLQFP-LQFP-REFLOW.pdfShow quoted textHide quoted text
> >
> > (i could not find the footprint for HVQFN48 package...)
> >
> > joseph