Hi Eric,

The 1.05 mm sounds excellent to me, it's provides you with enough
placement-tolerance without the risk of solder bridging.
I'm surprised that it's not the IPC-SM-782.

Daan Terstegge
http://www.smtinfo.net


----- Original Message -----
From: "Eric Christison" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 24, 2003 5:55 PM
Subject: [TN] Pad Pitch to width ratios


> Perhaps someone can give me an opinion on this one.
>
> I've been asked to approve the design of a surface mount device which has
QFP
> type legs, 0.75mm wide on a 1.4mm pitch.
>
> The vendor is recommending a PCB pad layout for the device where the pads
are
> 1.05 wide on (obviously) a 1.40mm pitch. The part would be used in high
volume
> consumer electronics.
>
> Would anyone out there anticipate any soldering problems with this
geometry? I
> had a look through IPC-SM-782 but didn't find it much help.
>
> Thanks,
>
> --
> Eric Christison
> Mechanical Engineer
> STMicroelectronics
> 33 Pinkhill
> Edinburgh
> EH12 7BF
>
> tel:    +44 (0)131 336 6165
> fax:    +44 (0)131 336 6001
>
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