Circuit board layout is a critical stage in the process of creating electronic devices. It involves transforming a schematic into a physical design that can be fabricated into a printed circuit board (PCB). Thus creating a circuit board layout is part of PCB design process. In this blog post, we will explore the essential steps involved in circuit board layout, from capturing the schematic to generating the necessary artworks for fabrication. So, let's dive in and uncover the key aspects of this fascinating process!
Section 1: The Journey Begins - From Schematic to Netlist
Once you have a schematic captured, error checked, and netlisted, you are ready to embark on the exciting journey of circuit board layout. We'll discuss how the netlist, which contains the connectivity information, plays a crucial role in the subsequent steps.
Section 2: Circuit Board Layout Process - Akin to Schematic Capture
Understanding the similarities between circuit board layout and schematic capture is essential for grasping the layout process effectively. We'll break down the main steps involved in capturing a schematic, such as generating symbols, placing them, and connecting them. We'll then draw parallels to circuit board layout, highlighting the equivalent steps: generating component footprints, placing footprints (placement), and connecting footprints (routing).
Section 3: The Building Blocks - Component Footprints
To construct a circuit board, we need to understand the concept of component footprints. These physical descriptions of components comprise padstacks, obstacles, and text. We'll examine a practical example and clarify how footprints represent different package types. Additionally, we'll touch upon the flexibility of generating footprints according to your company's standards or creating your own standard. A footprint is a physical representation of a component and comprises padstacks, obstacles, and text. An PCB footprint example is shown below.
Section 4: Decoding the Terminology - Layers and Obstacles
To navigate the world of circuit board layout effectively, we need to familiarize ourselves with the terminology. We'll explore the concept of layers, which play a vital role in creating footprints and padstacks. Understanding layers allows us to control the connections made on specific layers of the circuit board. We'll delve into common layer names and their corresponding functions. Additionally, we'll define obstacles, which are outlines or shapes representing objects on a circuit board that impact placement or routing. In the above illustrated PCB footprint, the rectangle in the middle of the part is a silkscreen obstacle, while the outer rectangle serves as a component placement outline obstacle.
A circuit board can have multiple layers. Here is a list of the more common ones:
- Top: Top or component layer
- Bottom: Bottom or solder layer
- Inner: All inner routing layers (inner1, inner2, etc.)
- Plane: Power and ground planes
- Solder mask top: Solder mask top
- Solder mask bottom: Solder mask bottom
- Solder paste top: Solder paste top
- Solder paste bottom: Solder paste bottom
- Silkscreen top: Silkscreen top
- Silkscreen bottom: Silkscreen bottom
- Assembly top: Assembly top
- Assembly bottom: Assembly bottom
- Drill Drawing: Drill Drawing
- Drill: Drill holes and sizes
- Fabrication Drawing: Fabrication drawing
- Notes: Notes
Conclusion
Circuit board layout is an intricate process that bridges the gap between schematic design and physical fabrication. By following the steps outlined in this guide, you can effectively transform your schematic into a functional PCB ready for manufacturing. Understanding the importance of netlists, component footprints, layers, and obstacles empowers you to create precise and reliable circuit board layouts. So, start your circuit board layout journey with confidence and unlock the endless possibilities of electronic design!
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