The 6118 standard of IEC internationaleletrotechnicalcommission recognizes the need for different objectives of welding fillet or pad bulge conditions. This new international standard identifies two basic methods of providing information for the development of pad shapes:

1) Accurate data based on industrial component specifications, PCB copy manufacturing and component mounting accuracy. These pad shapes are limited to a specific component and have a number identifying the pad shape.

2) Some equations can be used to change the given information to achieve a more robust welded connection, which is used in special cases where the accuracy used for mounting or installing equipment is more or less different than that assumed when determining pad details.

This standard defines the maximum, medium and minimum material conditions for pads used to mount various pin or component terminals. Unless otherwise indicated, this standard marks all three "desired goals" as level 1, level 2 or level 3.

Level 1: maximum - for low-density product applications, "maximum" pad conditions are used for wave crest or flow welding of pin free sheet elements and pin fin elements. The geometry configured for these elements and inward "t" pin elements provides a wide process window for manual soldering and reflow soldering.

Level 2: Medium - this "medium" pad geometry can be considered for products with medium level element density. Very similar to the ipc-sm-782 standard pad geometry, the medium pad configured for all component types will provide a robust soldering condition for the reflow soldering process, and should provide appropriate conditions for wave or flow soldering of leadless and fin pin components.

Level 3: minimum - products with high component density  usually portable product applications can consider "minimum" pad geometry. The choice of minimum pad geometry may not be appropriate for all products. Before adopting the minimum pad shape, the use of this should consider the limitations of the product and conduct the test based on the conditions shown in the table.

Pad geometries provided in ipc-sm-782 and configured in iec61188 shall accept component tolerances and process variables. Although the pads in the IPC standard have provided a robust interface for most assembly applications of users, some companies have expressed the need to adopt the minimum pad geometry for portable electronic products and other unique high-density applications.

The international pad standard (iec61188) understands the requirements for higher part density applications and provides information on pad geometry for special product types. The purpose of this information is to provide the appropriate size, shape and tolerance of surface mount pads to ensure sufficient area for proper welding fillet, and to allow inspection, testing and rework of these welding points.