PCB Patterns include traces, holes, pads, annular rings and all other features. In PCB manufacturing, we address different patterns into land pattern, circuit pattern, solder mask pattern and etc. PCB patterns formation is starting to shift away from the mask exposure technique used in the past toward direct exposure which can draw the circuitry directly using fine lines. As PCB patterns achieve higher densities, the pattern formation process needs to handle finer pattern widths and more accurate alignment of PTHs and blind holes with the patterns.
Pattern vs. Footprint
In PCB assembly industry, the glossary Land Pattern and Footprint are often used interchangeably. These two terms are similar, but there is minor difference between them. Understanding the difference is functionally useful. In fact, a specific component could have multiple different land patterns, but it will always have a single footprint.
- Footprint: A component’s footprint officially refers to the actual physical size of a given component. If you were to painstakingly measure the body and the leads of a given component and draw out a drawing using those dimensions, you would then have the part’s footprint. To put it in a more relatable way, the footprint of a component is much like the footprint of a person: It is the imprint that component would create if you were to press it down in soft sand.
- Land Pattern: It refers to the size of the pads and outline for a given part that should be designed onto a PCB. Both manual and automated soldering processes require that the pads designed for a part should be larger than the leads to which they will be soldered, so the land patterns should always be slightly larger than the footprint for any component. You can normally find land patterns’ recommendations in manufacturer’s datasheet.
One of the most important aspects of MADPCB’s comprehensive DFM check service is out footprint vs. land pattern comparison. Before PCB production starts, our CAM engineers will compare the land patterns for each part in your design with documented footprint dimensions to ensure a high quality PCB assembly. This service pre-empts manty common PCB defects then can occur due to land patterns being either too large or too small for their associated footprints.