IPC-7351 Land Pattern Naming Convention | |||
Item ID |
PC2004-2-16 |
Author |
Tony Folan |
Applies to |
PCB: General |
||
Created |
31/10/05 |
Last modified |
31/10/05 |
The IPC-7351 standard provides an intelligent land pattern naming convention that aids in communication between engineering, design and manufacturing. Containing information on attributes such as component family, pin pitch, pin quantity and lead span, the convention also provides for enhanced search capabilities within the IPC-7351 Land Pattern Viewer.
A standard land pattern naming convention should use the physical attributes of the component and be consistent throughout. The IPC-7351 Land Pattern Naming Convention was accepted by NIST and published as a world standard.
The following table shows a sample for SMT SOICs.
Land Pattern Geometry variations:
The primary concept of IPC-7351 revolves around three new application-specific land pattern geometry variations that are designed to support various levels of product complexity. IPC-7351 acknowledges that variables such as component board density, high shock environments and the need for rework and repair all contribute to the need for more than just one land pattern recommendation.
The IPC-7351 standard provides the following three and pattern geometry concepts for each component that the user may select from:
- Density Level A: Maximum (Most) Land Protrusion — for high component density applications typical of portable/hand-held products and products exposed to high shock or vibration. The solder pattern is the most robust and can be easily reworked if necessary. Example: Washing Machine.
- Density Level B: Median (Nominal) Land Protrusion — for products with a moderate level of component density and providing a robust solder attachment. Example: Home Entertainment System.
- Density Level C: Minimum (Least) Land Protrusion — for miniature devices where the land pattern has the least amount of solder pattern to achieve the highest component packing density. Example: Mobile Phone.
Looking back at the Sample Naming Convention table we can see how these levels are incorporated into the Land Pattern Naming convention using the abbreviations M, N and L.