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

  • From: "Ritter, Alan" <Alan.Ritter@xxxxxxxxxx>
  • To: "icu-pcb-forum@xxxxxxxxxxxxx" <icu-pcb-forum@xxxxxxxxxxxxx>
  • Date: Thu, 26 Jan 2012 10:03:23 -0500

Gary noted:

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.

Gary:

That was my initial reaction as well but it seems the theory is that you lay 
down a layer of solder paste that is thicker than the soldermask thickness, so 
the thermal pad makes contact with the paste.  We have built several thousand 
boards like this and haven't seen an appreciable failure rate due to poor 
thermal contact, so it seems the Cypress technique works reasonably well.  (and 
I guarantee you that this particular USB hub will overheat if it doesn't have a 
good thermal contact...our prototype boards didn't have the recommended thermal 
pad layout and half of them would overheat and shut down the USB hub pretty 
quickly.)


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@01CCDC09.30F9DEC0]




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.

PNG image

Other related posts:

  1. Home
  2. icu-pcb-forum
  3. Archive
  4. 01-2012