[PCB_FORUM] Re: Thermal Pad vias-to-gnd plugged?

  • From: "Macindoe, Gary" <Gary.Macindoe@xxxxxxxxxxxx>
  • To: "icu-pcb-forum@xxxxxxxxxxxxx" <icu-pcb-forum@xxxxxxxxxxxxx>
  • Date: Thu, 26 Jan 2012 14:55:26 +0000

Thanks for the reply and PDF Alan.

So Cypress is suggestion that the vias to ground be masked over on the Top. It 
seems like that would keep the part up off of the pads.

Thanks again.

Regards,

Gary MacIndoe
Senior PCB Design Engineer
EbD R&D Hardware
Surgical Solutions Group
Covidien
5920 Longbow Drive
M/S A20
Boulder, CO 80301

303.476.7458
www.covidien.com

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx 
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Ritter, Alan
Sent: Wednesday, January 25, 2012 3:59 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Thermal Pad vias-to-gnd plugged?

We had to do this with a USB hub chip from Cypress.  Their layout guidance 
included tenting the vias with soldermask to prevent wicking.  Take a look at 
the layout guidelines on page 23 of the CY7C65640A at:

http://www.cypress.com/?docID=31749

Just one example...

Alan Ritter
Surgical Equipment Design & Development
Engineering Fellow

(636) 226-3364 (Office)
(636) 226-3552 (FAX)
(314) 488-1139 (Mobile)

Bausch + Lomb
3365 Treecourt Ind. Blvd.
St. Louis, MO  63122
www.bausch.com<http://www.bausch.com/>
[cid:image001.png@01CC4AD6.929A3C20]

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx 
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Macindoe, Gary
Sent: Wednesday, January 25, 2012 4:50 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Thermal Pad vias-to-gnd plugged?

Hey guys,

When you have an IC with a thermal pad (e.g. A/D), the typical requirement is 
to put vias in the center pad that is connected to the gnd plane for heat 
wicking.

Do you worry about the solder paste going down the vias, even with a 10 mil 
drill? My coworker is concerned that this will happen.

I haven't had this concern, have never "plugged" etc. the vias with no negative 
feedback.

Regards,

Gary MacIndoe
Senior PCB Design Engineer
EbD R&D Hardware
Surgical Solutions Group
Covidien
5920 Longbow Drive
M/S A20
Boulder, CO 80301

303.476.7458
www.covidien.com








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