Recently our department was asked to design a board that included LCC cases among which some LCC-20s . As we had no previous experience ,we refered to IPC-SM-782 Rev.A where we were pleased to locate the geometric characteristics of the component in section 12.3 page 2 and the relevant proposed land pattern under RLP code 831. 

When we tried to make a model in our CAD system we realized that if we used the data of the IPC standard the clearance between pins 3 and 4 would be 0.22 mm and this could be achieved only if we used the shaded LMC values as design values ( which in our opinion is not right ).

               3 
               = = = = = 
           4 =           =
             =           =
             =           =
             =           =  
             =           =
               = = = = =

Do we interpret the data in a wrong way ? Is there any newer revision to IPC-SM-782 ? Has anyone used efficiently other land patterns for LCCs ?

Theodore Alimissis
CAD Department Manager
Intracom SA , Greece
e-mail : [log in to unmask]