Given the larger cost of the manufacturer producing the package with a
thermal pad on the bottom of the chip, and the extra packaging
challenges present (ie placing the die in intimate contact with the
thermal pad) then it is preferred to connect up the thermal pad to a
copper area on the board, and to have this copper area large enough to
dissipate the heat required.
If using the chip in a very low power mode (ie not using the full
designed capabilities of the chip) then it may be easier to not connect
the thermal pad to anything, however if you don't know whether your
design will indeed remain within the reduced power dissipation limits,
then you should always follow the manufacturers recommendations
regarding the copper connectivity of the thermal pad. The manufacturer
generally always recommends connecting it to a copper area on the
component side, and then vias to conduct heat away from the component
side copper to a more exposed copper region.
no. its optional, for additional cooling if required. it's not.
----- Original Message -----
From: "Jim Walker" <[EMAIL PROTECTED]>
To: "Protel EDA Discussion List" <[email protected]>
Sent: Sunday, December 25, 2005 2:58 PM
Subject: Re: [PEDA] Touch up Solder mask?
Forgive me if I am missing the point but isn't the pad on the bottom of
the IC there for the purpose of being soldered to a matching pad on the
board? Isn't it necessary for heat sinking or grounding?
Jim Walker
Walker Power Design, Inc.
www.walkerpowerdesign.com
Leonard Gabrielson wrote:
Thanks very much guys!!
Len G.
----- Original Message -----
From: "Harry Selfridge" <[EMAIL PROTECTED]>
To: "Protel EDA Discussion List" <[email protected]>
Sent: Saturday, December 24, 2005 3:37 PM
Subject: Re: [PEDA] Touch up Solder mask?
Here's a page for an overcoat touchup pen sold by DigiKey:
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=75&M=CW3300G
and here's a page for high temperature Kapton tape that can be used
as a temporary solder resist covering:
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=19&M=5413%20%201/2%22
Regards - Harry
At 01:44 PM 12/24/2005, you wrote:
oops. let me try this again...
Hello all,
I have an 8-pin SOIC that has an exposed ground pad on the bottom of
it (Analog Devices AD8000), and find that there are a couple of vias
under the IC that I am afraid might be shorted by this pad.
Does someone know of where to buy a small quantity of touch-up
solder mask so I can cover the IC pad or the vias before wave
soldering?
Thanks much, & Merry Christmas.
snip
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