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 PRIVILEGE AND CONFIDENTIALITY NOTICE: The information contained in and/or attached to this e-mail message is intended solely for the use of the addressee and may contain information that is legally privileged, confidential or exempt from disclosure. If you think you received this message in error, please notify the sender immediately by replying to the email and then delete it from your computer. Do not disclose the contents to anyone. Thank you.