Introduction

Printed Circuit Board (PCB) design and manufacturing is a complex process that requires various types of documentation at different stages. Whether you are designing a PCB for a hobby project or a commercial product, having the right documentation is crucial for ensuring that your PCB is manufactured correctly and functions as intended.

In this article, we will discuss the different types of files and documents that you need for bare boards, PCB assembly, and PCB documentation. We will also provide some tips on how to create and manage these documents effectively.

What is PCB Documentation?

PCB documentation refers to the set of files and documents that are used to design, manufacture, and assemble a PCB. These documents provide detailed information about the PCB, including its schematic diagram, layout, bill of materials (BOM), assembly instructions, and testing procedures.

PCB documentation is important for several reasons:

• It helps to ensure that the PCB is designed and manufactured correctly, according to the required specifications.
• It provides a record of the PCB design and manufacturing process, which can be useful for troubleshooting and future reference.
• It facilitates communication between the different parties involved in the PCB design and manufacturing process, such as the designer, manufacturer, and assembler.

Types of PCB Documentation

There are several types of documents that are commonly used in PCB design and manufacturing. These include:

Schematic Diagram

The schematic diagram is a graphical representation of the electrical connections between the components on the PCB. It shows the components as symbols and the connections between them as lines.

The schematic diagram is the starting point for PCB design, as it defines the electrical functionality of the PCB. It is also used for troubleshooting and testing the PCB.

PCB Layout

The PCB layout is a graphical representation of the physical arrangement of the components on the PCB. It shows the exact location and orientation of each component, as well as the copper traces that connect them.

The PCB layout is created based on the schematic diagram and takes into account various design constraints, such as component footprints, trace widths, and clearances.

Bill of Materials (BOM)

The bill of materials (BOM) is a list of all the components that are used on the PCB. It includes information such as the component name, manufacturer part number, quantity, and reference designator.

The BOM is used by the PCB assembler to procure the necessary components and assemble the PCB. It is also used for inventory management and cost estimation.

Assembly Drawing

The assembly drawing is a graphical representation of how the components should be assembled on the PCB. It shows the location and orientation of each component, as well as any special assembly instructions.

The assembly drawing is used by the PCB assembler to ensure that the components are placed correctly on the PCB. It is also used for quality control and inspection.

Fabrication Drawing

The fabrication drawing is a graphical representation of the physical characteristics of the PCB, such as its dimensions, layer stackup, and drilling requirements.

The fabrication drawing is used by the PCB manufacturer to fabricate the bare board according to the specified requirements. It is also used for quality control and inspection.

Gerber Files

Gerber files are a set of files that contain the information necessary to manufacture the PCB. They include the copper layer images, solder mask, and silkscreen layers.

Gerber files are the industry standard for PCB manufacturing and are used by PCB manufacturers to create the photomasks and drill files necessary for PCB fabrication.

Drill Files

Drill files contain the information necessary to drill the holes in the PCB. They specify the location, size, and type of each hole.

Drill files are used by the PCB manufacturer to program the drilling machines and ensure that the holes are drilled correctly.

Test Procedures

Test procedures are documents that outline the steps necessary to test and verify the functionality of the PCB. They may include instructions for visual inspection, electrical testing, and functional testing.

Test procedures are used by the PCB assembler and the end user to ensure that the PCB is functioning correctly and meets the required specifications.

Creating and Managing PCB Documentation

Creating and managing PCB documentation can be a complex and time-consuming process. Here are some tips to help you streamline the process:

Use a Version Control System

Use a version control system, such as Git or SVN, to manage your PCB documentation. This will allow you to track changes, collaborate with others, and revert to previous versions if necessary.

Use a PCB Design Tool

Use a PCB design tool, such as Altium Designer or KiCad, to create your schematic diagram and PCB layout. These tools will automatically generate many of the necessary files, such as Gerber files and drill files.

Use a BOM Management Tool

Use a BOM management tool, such as OpenBOM or Arena PLM, to create and manage your BOM. These tools will help you to ensure that your BOM is accurate and up-to-date.

Use a Documentation Template

Use a documentation template to ensure that your documentation is consistent and complete. Many PCB design tools come with built-in templates for common document types, such as assembly drawings and fabrication drawings.

Review and Verify Your Documentation

Review and verify your documentation before sending it to the manufacturer or assembler. This will help to catch any errors or omissions and ensure that your PCB is manufactured and assembled correctly.

Bare Board Documentation

Bare board documentation refers to the set of files and documents that are used to manufacture the bare PCB board, without any components assembled on it. The bare board documentation typically includes:

• Gerber files
• Drill files
• Fabrication drawing

These files are sent to the PCB manufacturer, who uses them to create the bare board according to the specified requirements.

PCB Assembly Documentation

PCB assembly documentation refers to the set of files and documents that are used to assemble the components onto the bare PCB board. The PCB assembly documentation typically includes:

• Bill of materials (BOM)
• Assembly drawing
• Pick and place file
• Test procedures

These files are sent to the PCB assembler, who uses them to procure the necessary components, assemble the PCB, and test it for functionality.

Document Type	Bare Board	PCB Assembly
Gerber files	X
Drill files	X
Fabrication drawing	X
Bill of materials (BOM)		X
Assembly drawing		X
Pick and place file		X
Test procedures		X

FAQ

What are the most important documents for PCB manufacturing?

The most important documents for PCB manufacturing are the Gerber files, drill files, and fabrication drawing. These documents contain all the information necessary to manufacture the bare PCB board.

What are the most important documents for PCB assembly?

The most important documents for PCB assembly are the bill of materials (BOM), assembly drawing, and pick and place file. These documents contain all the information necessary to assemble the components onto the PCB board.

Can I use the same documentation for bare board manufacturing and PCB assembly?

No, bare board manufacturing and PCB assembly require different sets of documentation. Bare board manufacturing requires Gerber files, drill files, and fabrication drawing, while PCB assembly requires BOM, assembly drawing, and pick and place file.

What happens if I provide incomplete or incorrect documentation?

Providing incomplete or incorrect documentation can lead to delays, errors, and additional costs in the PCB manufacturing and assembly process. It is important to review and verify your documentation carefully before sending it to the manufacturer or assembler.

How can I ensure that my documentation is complete and accurate?

To ensure that your documentation is complete and accurate, use a PCB design tool to generate the necessary files, use a documentation template to ensure consistency, and review and verify your documentation before sending it to the manufacturer or assembler.

Conclusion

PCB documentation is a critical part of the PCB design and manufacturing process. It ensures that the PCB is manufactured and assembled correctly, according to the required specifications.

There are several types of documents that are commonly used in PCB design and manufacturing, including schematic diagrams, PCB layouts, bills of materials, assembly drawings, fabrication drawings, Gerber files, drill files, and test procedures.

Creating and managing PCB documentation can be a complex and time-consuming process, but there are several tools and techniques that can help to streamline the process, such as using a version control system, PCB design tool, BOM management tool, and documentation template.

By understanding the different types of PCB documentation and how to create and manage them effectively, you can ensure that your PCB is manufactured and assembled correctly and functions as intended.