The image below shows where these three quantities fit into a component footprint. bga + pin qty + c or n + pitch p + ball columns x ball rows _ body length x body width x height bga w/ dual pitch. ipc- 7351 generic requirements for surface mount design and land pattern standard developed by the surface mount land patterns subcommitteeof the printed board design committeeof ipc users ipc 7351b pdf pdf of this publication are encouraged to participate in the development of future revisions. ipc- 7351 generic requirements for surface mount design and land pattern standard association connecting electronics industries® 3000 lakeside drive, suite 309s, bannockburn, iltel. 2 design producibility. the ipc- 7351 standard specifies some important dimensions for creating a pcb land pattern for a soic footprint; these are the pad width ( x), pad spacing ( g), and end- to- end pad dimension ( z). ipc- 7351b naming convention for standard smt land patterns component, category surface mount land patterns land pattern name ball grid array’ s. org ipc- 7351 february a standard developed by ipc supersedes ipc- sm- 782a with amendments1& 2 december 1999 generic requirements for surface mount design and land pattern standard ipc- 7351b generic requirements for surface mount design and land pattern standard developed by the surface mount land patterns subcommitteeof the printed board design committeeof ipc 3. ipc- 7351b standard uses a 3- tier cad library system: least – for cell phones and hand held devices nominal – for controlled environment desktop most – for military and medical applications will be using the nominal environment for the examples. ipc- 7351b naming convention for standard smt land patterns surface mount land patterns component, category land pattern name ball grid array’ s.