We've had electrical requirements that are aided by not using SMT thermals on many of our boards.  Been doing it for years, and have not seen a significant impact.  There's pros and cons to both methods, you have to weigh them for your own situation.

Richard, you mentioned the thermal mapping.  We generally have only looked at areas of the board for variations.  Have you studied boards in enough detail to measure the variation from a relieved pad to it's plane?  What have you seen?

Or to be curious, would the areas of missing copper around the pads be a significant factor in the overall heat absorption of the plane?  Just the fact that there's less overall mass and some difference in the surface areas (3 dimensional) should be measurable, but is it significant?

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0.
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------