----- Original Message -----
From: "Matt Pobursky" <
piclist@...>
To: <
piclist@...>
Sent: Sunday, July 20, 2008 12:24 AM
Subject: [PIC] Center Pad Connection on PIC18F25J10-I/ML QFN Package
> Does anyone know for certain what the center exposed pad on a
> PIC18F25J10-I/ML QFN package is connected to?
>
> I have read and re-read the datasheet for the part and can't find any
> reference to it at all. Most datasheets will have a note indicating what
> the pad is connected to (or not) and what to connect it to in your
> footprint. I'm laying out a PCB for it and I'd like to know for sure.
>
> Matt Pobursky
> Maximum Performance Systems
>
Matt,
>From a Microchip Knowledgebase entry:
http://support2.microchip.com/KBSearch/KB_Ticket.aspx?ID=Tt6UJ9A000278"The center pad is primarily for heat transfer, and is integral to the QFN
package design.
Most of our products do not generate enough heat to be concerned with, but
the exposed pad is unavoidable. The exposed pad is the underside of the die
attach paddle.
The die is typically attached to the paddle using a conductive epoxy. That
means the exposed pad is electrically conductive to the substrate of the
die, which is usually ground in our products. We do not recommend putting
PCB traces under the exposed paddle, except for thermal relief.
The center pad should not be connected electrically to ground or power."
I hope this helps.
Richard
--
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
