Hi,
I have been told in my C.I.D. seminar that the land pattern for I.C. like the QFP should use the land with the full radius instead of the squared ones. In fact the "Full Radius Optional" is a printing error in the IPC-SM-782-A. The squared ones are the optional.
Louis Guérin, C.I.D.
Conception de Plaquette de Circuit Imprimé | PCB Designer
Lyrtech Inc.
Téléphone - International / Phone - Worldwide: +1-418-877-4644 #291
Sans frais - Canada & É.-U. / Toll Free -.Canada & USA: +1-888-922-4644 #291
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-----Message d'origine-----
De : TechNet [mailto:[log in to unmask]] De la part de Tempea, Ioan
Envoyé : 24 mars 2004 13:43
À : [log in to unmask]
Objet : Re: [TN] FW: Round SMT pads...DILEMMA
Now that's an interesting point of view.
For quite a while I try to gather information on the eventual PCB design
changes that lead-free would bring. Our designers are reluctant to changes,
they see lead-free as a pure manufacturing problem. But they would comply,
in case I come up with something solid. They are using IPC-SM-782 right now
and they would only change if I could give them something as solid.
Are these round pads covered by any sort of spec?
Do the round pads apply only to passives? What packages (0402 up to what)?
What does round mean, circular or elliptical?
Thanks,
Ioan
> -----Original Message-----
> From: Brian J. Toleno, Ph.D. [SMTP:[log in to unmask]]
> Sent: Wednesday, March 24, 2004 1:29 PM
> To: [log in to unmask]
> Subject: Re: [TN] FW: Round SMT pads
>
> Another reason for rounded pads is when using Pb-free solders, due to the
> increase in surface tension and wetting angle, people are moving to
> rounded pads so that they don't have exposed corners after reflow.
>
> Brian J. Toleno, Ph.D.
> Sr. Applications Chemist
> Loctite Electronics
> 15051 East Don Julian Rd
> Industry, CA 91746
> Ph: 626-968-6511 x304
> Cell: 626-215-0879
>
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