Hello TechNet users
     
     I am in need of some input about the necessity of having thermal 
     relief patterns on inner planes for vias that are being used to 
     connect surface mount devices to the inner plane.
     
     The design in question is 1.6mm thick, 4-layer, mixed technology with 
     via size of 0.6mm. The leaded devices that connect directly to the 
     plane have the IPC recommended thermal relief patterns.
     
     My main question is, are there any major concerns or advantages in 
     having the vias connecting directly into the plane without relief, I 
     vaguely recollect concern expressed over reliability of these 
     connections if extreme thermal cycling is undertaken.
     
     Can anybody help
     
        Regards  Gary Willard (Substrate Design Engineer - UK)