All You Need to Know About BOM File PCBA

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You need a BOM file when assembling electronic products, for example, printed circuit boards. BOM is important to provide a comprehensive list of estimated costs and assembly materials. Every PCB assembler needs a BOM file to streamline the PCB assembly process. This file can drive positive outcomes from various operational processes such as PCB parts sourcing, manufacturing, third-party assembly, and more.

Therefore, it is highly important to create an organized, accurate, and updated BOM file PCBA.

Everything you need to know about BOM file PCBA

Whenever it is about BOM file PCBA, most people don't know what this is, especially non-techies. We have brought a complete guide here to make you understand what a BOM file is in PCB assembly and its important aspects. Look at the details below to know everything you must know about BOM file PCBA.

So, here we go:

What is BOM file PCBA?

BOM file, aka Bill of materials in PCBA, serves as a base to build PCB products. It is a fundamental data set that is used throughout the assembly process. A properly created BOM file can communicate all the important technical ingredients necessary to develop a PCBA product.

A properly designed BOM file can give details about multiple PCB assembly aspects. Generally, these aspects include:

  • Cost of sold goods
  • Lead time for product materials procuring
  • Design quality for assembly
  • Manufacturing process details
  • Robustness of supply chain
  • Determining cash flow requirements.

A BOM is a list of assemblies, parts, items, and other materials necessary to complete the PCB production and assembly process. It also consists of instructions to gather and use required material in PCB production. All manufacturers building PCB products start the process by creating a BOM file PCBA. No matter which industry you operate, accessing a BOM file is essential for PCB assembly.


Why is the BOM file used in PCBA?

The BOM file PCBA can help you pull together all the essential information about PCBA. Several disciplines consume BOM data to complete their jobs rightly. These usually include:

  • Designers
  • Engineers
  • Operations
  • Documents control
  • Purchasing
  • Manufacturing
  • Assembling
  • Contract manufacturers etc.

PCB assemblers, engineers, and manufacturers rely on BOM files heavily as these files provide effective results for different activities. These activities range from parts sourcing to manufacturing and product assembling.

Other than these, creating, organizing, and updating BOM files is also highly important for two major purposes. Let’s get to know about these purposes below for a better understanding:

To estimate PCBA costs

PCBA cost estimation is important, especially when designers are at the initial stages of PCB product designing. Not having cost estimation can lead designers to have tough times meeting their PCB product budgets. Therefore, it’s necessary to have a record in hand to determine the number of boards, parts, and materials required to complete a certain project.

The primary purpose of creating a BOM file is to estimate the PCB assembly costs. It will enlist all the necessary components for PCB assembly. Consequently, creating a cost check isn't difficult for PCB assembly units.

To get information for bringing all PCB components under one roof.

During the PCB assembly process, the BOM file helps get all the required information about PCB components in the same place. These files can provide information about reference designators, material quantity, quality, footprints, and more. BOM files can help product designers save time by providing a list of all updated parts. This will also prevent them from redesigning a PCB in later stages. Overall, an updated and properly organized PCB can help in saving time, money, and effort.

What’s included in BOM file PCBA?

An effective BOM file for PCBA must include the following factors:

BOM Level

Under this information category, you will assign each assembly level a specific number to describe where it stands in the BOM hierarchy. This information will help anyone to understand BOM structure quickly.

The part number for each component

Assign a unique number for quick parts identification. Manufacturers either opt for an intelligent or non-intelligent number scheme for PCB parts. Whatever type of numbering scheme you use, avoid using multiple numbers for the same part and vice versa.

Part name for each PCB component

Add a specific name of each PC part for quick identification of it.

The phase of each part in the lifecycle

Add information about at which phase each PCB part is in the lifecycle. For example, use In Production for PCB parts that are under production. You can use “In Design or Unreleased” for parts that haven’t been approved yet. This information provides help in NPI because it allows for tracking and creating efficient project timelines.  

A detailed description of each PCB part

Providing each part’s detailed description can help the assembly line easily differentiate similar and specific parts.

Several parts are required.

Record the number of PCBA parts that will be used in the process of PCB assembly and subassembly. This will also help guide the right manufacturing and purchasing activities and decisions.

Unit of measure

This information will provide details regarding the measurement classification in which a PCB part is used or purchased. Using standard units such as ounces, feet, inches, and suitable classifications is common. Ensure to stay consistent for similar types of parts to stay right on creating and delivering quantities to the assembly line.

Reference of designators

Adding reference designators provide details on where a PCB part will fix on the board. This information will save a lot of your time and keep you from any confusion down the road.

Procurement type

The document will also include information regarding how each PCB component is made or purchased. This information will help create efficiencies in activities, i.e., procurement, planning, manufacturing, designing, and assembly.

BOM Notes

BOM files also capture important, relevant notes to keep everyone interacting with BOM on the same level.

Including all these things in your BOM file will streamline manufacturing and other business activities on target.

Tips for BOM file generation for PCBA

As creating a BOM file is highly important for multiple reasons. Therefore, it is always important to understand how you will create a more effective BOM file. So, here are some key tips for creating an effective BOM file for PCBA.

Always ensure to consider these tips to generate efficient and effective BOM files.

Create your BOM file as per your PCBA needs

Before creating your BOM file, determine who will use this file for PCB manufacturing and assembly. Understanding this will give you a direction in deciding what you need to add to your BOM file. Ultimately, it will become easier for you to design and create a BOM file that meets the specific needs of its consumers. Different companies create BOM files differently. It is because different projects have different BOM file information requirements. Therefore, creating a BOM file that can meet your consumers’ requirements is always better.

Ask for a BOM file template before requesting a quote

Every PCB manufacturer has a BOM file created. You can ask them to show you a BOM example before requesting any PCBA quote. This practice will help you to avoid issues in accessing and using BOM documents that can make them incompatible. Consequently, you can understand technical needs before getting a quotation easily.

Include all necessary details

Adding as much PCBA information to your BOM file as possible is always better. Always remember that the BOM file plays a significant role in explaining the overall PCB assembly process. This will keep people from building PCB projects from scratch.

Always keep your BOM file as detailed, précised, and clear as possible.

Double-check the information added in the file

Always double-check the information added in the BOM file before sending it to the manufacturer or assembly unit. This will help you ensure that this file's added information is accurate and up-to-date. Also, ensure that the document is easier to navigate and understand for your audience.

Don’t forget to track any changes.

While working on a PCB project, it’s always important to have a system to keep document changes’ on track. Tracking any changes will make it easier to refer back to those whenever needed. Label each version clearly and use the latest one for assembly and manufacturing projects.

Restrict BOM file PCBA editing

At times, multiple people may need to access your BOM file. Therefore, it is always important to avoid giving file editing permissions to any of them unless it is important. Offer read-only access to the consumers and prevent unnecessary editing in the BOM file. This practice will keep you from any unwanted changes or accidental misinformation in the file.

If you provide access to edit, assign a distinct identifier for each user. This practice will make it easier to understand whom you need to question in case of a problem.

Final thoughts

BOM file is an important aspect of PCB design, manufacturing, and assembly. Therefore, creating it right is vital. You can use the information mentioned above to create effective BOM files. However, introducing automation in BOM file management can also be a good step.


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