**What are the File Types for PCB Design Input and Output?**

1. **Introduction to PCB Design**

PCB (Printed Circuit Board), also known as a printed circuit board, is a crucial electronic component that serves both as a support structure for electronic parts and a means of providing electrical connections between them.

Since the early days of connecting carbon and silicon chips to create functional electronic devices, PCBs have been the backbone of the electronics industry. Over time, the design process has evolved from manually drawing PCB layouts to utilizing advanced component libraries, automated layout, and routing functions. This evolution has made PCB design increasingly accessible and efficient for engineers.

2. **Key Aspects of PCB Design**

The PCB design process is generally divided into several stages: schematic design, PCB layout, circuit simulation, CAM engineering software, and board copy software. Typically, PCB design software includes two main modules: schematic design and PCB layout. Some advanced PCB design tools even integrate these modules and additional features.

3. **File Types for PCB Design Input and Output**

What file formats are used for input and output during the post-processing phase of PCB design? Let’s take a closer look at the key types of files commonly used in the industry.


1. **PCB Design Input Data**

The input materials for PCB layout tasks primarily include: the schematic diagram, structural element diagram, design requirements, and the completion schedule for the single board plan.

(1) **Schematic Diagram**

The schematic diagram outlines the design principles of the circuit and the logical relationships between components. It serves as the foundation for PCB design, and a thorough understanding of it is crucial for successful PCB layout. The schematic mainly depicts the major functional blocks on the circuit board, the logical interconnections between these blocks, and the internal connections within specific modules.

For example, a small CPU system on the PCB typically includes: CPU, SDRAM, FLASH, Boot ROM, and other key components. Each main chip also includes its peripheral matching components and associated circuitry.

(2) **Structural Element Diagram**

This diagram defines the PCB’s size and shape, specifies the location requirements for special components (e.g., interface connectors, mounting holes, forbidden areas, height restrictions, etc.), and prioritizes the placement of devices as per the structural requirements.

(3) **Design Requirements**

These mainly consist of engineering requirement forms and reference documents.

(4) **Engineering Requirements Form Content**

The form typically includes layout and routing specifications for important signal traces on the PCB, such as: board thickness, impedance, spacing requirements for clock and differential signals, routing delays for key buses, and relative trace delays. It also covers power supply size requirements.

2. **Output Data After PCB Design Completion**

The output data generally include: assembly files, Gerber files, stencil files, structural files, and PCB source files.

(1) **Assembly Documents**

Naming convention: PCB board name + version number + ASM (e.g., PD_Ver_1_0_ASM).

Assembly file contents

(2) **Gerber Files**

Naming convention: PCB board name + version number + CAM (e.g., PD_Ver_1_0_CAM).

Gerber file contents

(3) **Stencil Files**

Naming convention: PCB board name + version number + SMD (e.g., PD_Ver_1_0_SMD).

Stencil file contents

(4) **Structural Documents**

Naming convention: PCB board name + version number + DXF (e.g., PD_Ver_1_0_DXF).

Structural file contents

(5) **PCB Source Files**

Naming convention: PCB board name + version number + PCB (e.g., PD_Ver_1_0_PCB).

The final output documents for the PCB design must be compiled into different types of packaging files as per specifications, in preparation for subsequent testing, processing, and assembly.