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This is a new one

Views: 1574

slthomas

#41485

This is a new one | 11 May, 2006

One of our customers' products has a couple of adjacent 0603 packages (one resistor, one cap) that are .010" apart. They are side by side, not end to end.

The adjacent pads between the two parts are electrically connected so bridging isn't an issue, but we built one today where both the cap and the resistor were pulled together at one end. They both have roughly the same side overhang on that one end (well within IPC 610C standards) and the bridge is extensive enough that they appear to share a fillet and also appear to be touching. We don't do any lead free so haven't sprung for 610D with the understanding that the D changes all covered lead free acceptance. Feel free to correct me on that while we're at it, if I'm wrong.

I can't find anything in 610 that characterizes this as a violation but it just seems wrong. Don't want to fix it if it ain't broke, though.

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Mike

#41562

This is a new one | 16 May, 2006

Hello, Heres my take. If the ends that are touching are connected by trace, and IPC-610 is satisfied, and the connection does not make a Parallel circuit where a series circuit is required, then I would treat it as a process indicator. That is, unless your DFM says otherwise. We had 0402 Rpacks that where all connected on one side. They would bridge from time to time. We left them alone as the issue was more cosmetic.

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RDR

#41563

This is a new one | 16 May, 2006

If the terms are connected electrically it does meet IPC

bridging between "non common conductors" is the defect

you should be fine, FYI, the .010" spacing is a violation of IPC 782

Russ

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#41565

This is a new one | 16 May, 2006

Thanks for the replies, fellas. Pretty much what I'd thought too, but you know, when it just doesn' LOOK right....

"the .010" spacing is a violation of IPC 782"

Not my problem. ;) You should see the decal they're using for the Xilinx PQFP 208. Not even close, but they don't wanna change it.

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Chunks

#41569

This is a new one | 16 May, 2006

Hi Russ,

Are you talking about Figure 3-8? I always took 782 as a "guideline" for recommended layouts versus poor layouts.

610 page 12-87 "anomalies" kinda shows what's being dicussed.

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RDR

#41574

This is a new one | 16 May, 2006

Yeah chunks, I do not know if it is spec or guideline, I refer to the "courtyard" grids for design, don't have the book handy so i am not sure if you are in the right place or not. i'll check though soon and post

russ

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RDR

#41575

This is a new one | 16 May, 2006

Steve just mentioned the 782 for ammo to customer, we usually get "it doesn't meet IPC" so we then say it was not designed to. let the pissin contest begin!

Russ

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Chunks

#41586

This is a new one | 17 May, 2006

No problem, I was just checking myself more than anything. Strange how they don't really specify this as a problem or not.

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