Jack,

As far as I know the reasoning behind "U" shaped pads was to keep the part from rolling off the lands.

I still use them but I am also not sure the added geometry is really needed.

Remember back when the reflow machine kinda shook as the PCB went through.

Newer machines probably do not have the same scale of vibration going on.

You should  be good just using rectangular pad geometries.

Good Luck,

FNK





Frank N Kimmey CID+

Electrical Engineer / PCB Design

VeriFone Inc

1400 W Stanford Ranch Road, Suite 200

Rocklin, CA 95765 USA

W: 1-916-625-1818

M: 1-916-833-9877

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-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson

Sent: Monday, December 04, 2017 8:56 AM

To: [log in to unmask]

Subject: [EXT] [TN] MELF land shapes



I am using MELF components on my current design, which I haven't seen much this century.

But I remember way back when we used "U-shaped" land shapes.



I notice the current Land Pattern standard (IPC-7351) recommends rectangular, but at least one person has suggested using U-shaped "just in case".

I generally resist that kind of philosophy unless there is science behind it.

Is anyone using U-shaped pads anymore?

(Is anyone using MELFs anymore? smile)



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