If you fancy yourself an outdoor person or enjoy wilderness camping and hiking, then you know that footprints can be your best friend—along with a well-calibrated compass. Footprints provide a map of the area’s traffic which can be extra helpful if there are any wild animals around. An even greater benefit is a blazed path that serves as a blueprint to follow.
When building PCBAs, footprint pad layouts work like blueprints. These landing patterns specify where to place each component and what traces run to and from them. Ensuring the components and pads match is critical for your board’s assembly. Therefore, you should incorporate a method or technique for acquiring or creating PCB footprint standards into your design process.
Why Are Standard PCB Footprints Needed?
Quantifying the different types of electronic components would be a daunting task, to say the least. However, defining repeatable landing pad formats or standard PCB footprints is virtually essential for today’s circuit board design and manufacturing processes. This is especially true for SMD components, where there may be dozens or even hundreds of pins, pads or balls.
Standard component footprints are beneficial as they help facilitate a smooth and efficient supply chain throughout the stages of board building.
Parts manufacturing: Builders and developers of components can utilize standard package sizes and their associated common materials and dimensions, which make it easier to build a wide variety of parts.
PCB designers: Engineers and PCBA designers can create their designs faster and more accurately when they utilize standard footprints, as even for new part numbers a good footprint should already exist
PCB fabrication: Standard footprints are fabricated millions of times a year, and are designed to be easy to manufacture.
PCB assembly: PCB assembly is the proving ground where the fabricated board footprint must match the component package footprint from the supplier. Any discrepancy can create faults during pick-and-place and/or soldering that will require rework, or worse, redesign. Standard footprints are designed to support robust high yield assembly processes.
As indicated above, standard footprints benefit the entire board-building process. However, best practices must be followed to acquire standard footprints and realize the benefits of efficiency and accuracy.
How to Best Utilize PCB Footprint Standards
For many designs that may use popular and common components, reliable and accurate 3D CAD models, including footprints, can readily be found online. Likewise, many of these may be included in your PCB design software tool’s parts library.
Using Online Footprints
If you locate the PCB footprint for your component online or within the parts database of your design software, you should utilize it. Such footprints have likely been verified against component manufacturer datasheets and implemented for many successful designs and board builds. However, it is always a good idea to verify the landing pattern yourself.
DFM for HDI Printed Circuit Boards
Creating a PCB Footprint Using the IPC 7351 Standard
For newer or exotic components, you may need to create footprints from scratch. The IPC 7351 standard provides guidelines to ensure footprints adhere to specific size, shape and tolerance restrictions. In this way, J-STD-001 soldering requirements can be met during assembly. In addition to following these guidelines, you must allow adequate space for the inspection of solder joint quality, as well as any necessary component testing or rework. Although no specific footprint regulations exist for through-hole components, there are applicable PCB layout standards for THT utilization.
Whether you acquire PCB footprint standards online, from your design program’s software library or create them yourself, be sure to follow the part manufacturer’s landing pattern and satisfy applicable IPC standard requirements. Perhaps the best way to meet these objectives is to collaborate with and rely on your CM’s expertise to build the best board that incorporates your design intent.
|Tempo's Custom PCB Manufacturing Service
Tempo Automation is the industry’s leading PCBA manufacturer for fast, high-quality boards for prototyping and low-volume manufacturing. From the simple to the highly complex, we are experienced in building boards that adhere to all applicable standards.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on how to use PCB footprint standards in your design, contact us.