Can't see that that patent can be made to stick. There is more than
enough prior art for circular pads of any size. It is sufficient to
state that the reason for the pretended "infringement" is that "we have
always done it that way, and the reason is nothing to do with the
lead-free or any other solder alloy". The claim states "tin-zinc based
solder, tin-silver based solder or tin copper based solder": Note the
"based". The text of the specification clearly mentions ternary and
higher alloys, including 2 SAC ones. It is therefore not likely to help
citing a ternary one.

Brian

David Greig wrote:
> US patent 6617529 might make life a little difficult. NIPPON ELECTRIC also have a Japan patent, but I can't find a Europe
> equivalent.
> You may want to try <http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=US2002074164&F=0&QPN=US2002074164> for a peak.
>
> Looks like square or non circular pads are going to be the thing. Or a circular pad extended to any distance from the hole and
> with one or more blind or thru vias any place within the circumference.
>
> Or perhaps solder with some lead content? What's the legal interpretation of "lead free"?
>
> Best Regards
>
> David Greig
> ______________________________
> GigaDyne Ltd
> http://www.gigadyne.co.uk
> ______________________________
>
> -----Original Message-----
> From: Leadfree [mailto:[log in to unmask]] On Behalf Of Colin Weber
> Sent: 19 August 2005 03:12
> To: [log in to unmask]
> Subject: [LF] Design of THT PAD Size
>
> Hi Folks,
>
> Can someone please point me in the right direction with respect to design guidelines for through hole device footprints to be
> wave soldered in lead-free manufacturing?
>
> I have heard that pads for THT device leads must be 30% larger.
> However, I don't know what IPC standard this figure or advice originates from and whether it refers to area, annulus, etc?
>
>
>
> Regards,
>
> Colin Weber
>
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