Certainly, I believe that there is no need to thermally relieve a via. The small length of track from the solder pad to the via will provide the thermal relief without needing a relief on the power/ground plane for the via. In the case of a BGA where the power connections are grouped under the central area of the device and you want to flood around those connections with a surface plane connected to an internal power/ground plane, I would do the following;
Connect the solder ball pads to the surface fill with a thermal relief pattern, and connect that fill to the internal plane with un-relieved vias. That way, the solderable pads are correctly relieved and the vias have a solid, continuous connection. Mr Lomax is quite correct in the difference between the vias and the power connections. The solder pad for the power connections must be thermally relieved. The via is not 'designed' to be soldered to. (The only situation where I have known this to be a problem is with microwave circuits, where the relief pattern can actually form a resonant LC 'tank'circuit and cause problems.) To quote Mary Sugden, a lot of PB design is actually 'solder joint design'. regards, Phil. -----Original Message----- From: Abd ul-Rahman Lomax [mailto:[EMAIL PROTECTED]] Sent: Tuesday, 5 February 2002 09:41 To: Protel EDA Forum Subject: Re: [PEDA] Thermal relief At 08:34 AM 2/5/2002 +1100, Colin Weber wrote: >I was talking with another designer, Phil Dutton, and he also recommended >the Power Connections Relieved. >"Make sure that your Power connections are relieved, or they will cool >down faster than the rest of the device, inducing stresses." That is "Power Connections." We've been talking about vias. Different animal. [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
