2. The first method involves accurate data based on industrial component specifications, PCB copy board manufacturing, and component placement accuracy capabilities. These pad shapes are specific to a particular component and are identified by a number that corresponds to the pad shape.
3. The second method involves using certain equations to modify the provided information to achieve a more robust solder connection. This is particularly useful in special situations where the placement or mounting equipment differs from the assumed accuracy when determining the pad details.
4. This standard defines the maximum, medium, and minimum material conditions for the pads used to mount various pins or component terminals. Unless otherwise specified, this standard designates all three “desired targets” as one, two, or three.
Level 1: For low-density PCB product applications, the “maximum” pad condition is used for wave or flow soldering of leadless chip components and leaded fin components. The geometry configured for these components, as well as inward “T”-shaped pin components, provides a wider process window for manual and reflow soldering.
Level 2: For products with medium component density, the “medium” pad geometry can be considered. This geometry closely aligns with the IPC-SM-782 standard pad design. Medium pads for all component types ensure robust soldering conditions for the reflow soldering process and are suitable for leadless and fin-shaped components. Wave crest or flow soldering offers appropriate conditions for these pads.
Level 3: For products with high component density, typically in portable applications, the “minimum” pad geometry may be used. However, minimum land geometry might not be suitable for all products. Before using the smallest land shape, consider the product’s specific requirements and conduct tests based on the conditions outlined in the table.
The pad geometry specified in IPC-SM-782 and configured in IEC61188 should accommodate PCB component tolerances and process variables. While the IPC standard pads offer a robust interface for most assembly applications, some companies require minimum pad geometries for portable electronics and other high-density applications.
The international PCB land standard (IEC61188) addresses the needs of higher part density applications and provides guidelines on land geometry for specific product types. This information aims to ensure the appropriate size, shape, and tolerances of surface mount pads, facilitating adequate soldering fillets, inspection, testing, and rework of solder joints.
