We use this technology on RF-boards. These look the same i.e. they are cooling studs for active elements with a high power loss. That some holes are open is probably because lack of full process control..I'll send to you a description of the process of maintaining heat spreading for a thyristor, a MESFET or whatever semi, by means of such objects like on your image. Inge On 13 March 2012 20:42, Charlie Pitarys <[log in to unmask]> wrote: > I have these PCB's (mixed technology) in house, used for an automotive > under > hood application. In several spots on the board are these array of holes. > On > the A-side a smt component like a thyristor will cover up the array. > What are these there for? > The wave flux residue is proving tenacious to effectively clean out of > every > via. Especially with the old school cleaning tool at this account. > > Some of the vias are clear but some have solder filling or partially > filling > them. These are now also filled with wave flux. > Below is a link to a picture of the array. > > http://i123.photobucket.com/albums/o319/dartfrogmts/Kyzen/A-Side00140xFCR145 > F20min-1.jpg > > I'll get them clean but curious as to why these are on the board. > Thanks in advance > > Charlie > > > > > CONFIDENTIAL > The content of this message, including any attachments, may contain > privileged and/or confidential information proprietary to Kyzen and is > intended only for the named addressees. If you are not the intended > recipient, you may not disseminate, distribute or copy this email. Please > notify the sender immediately by email if you have received this email in > error and delete this email from your system. > > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________