What is a Bill of Materials (BOM)?


A Bill of Materials (BOM) is a crucial document in the manufacturing industry. It lists in detail all the parts, raw materials, subassemblies, components and their quantities required in the manufacturing process of a product. Imagine that you are going to make a complex PCBA circuit board. The BOM is like a guide that lists in detail all the steps you need to make the board. With it, you will know which parts are needed and how to assemble them to complete the final product.

BOM is not just a list of parts, it is a core document for product design, manufacturing and maintenance. It helps us ensure that every link is carried out in an orderly manner. From designers to procurement personnel to production line workers, BOM is their common language.We have more detailed information about BOM here

What should be included in an effective BOM

An effective BOM should not only be detailed, but also accurate. Here are the main contents that should be included in the BOM:

1.BOM number

Each BOM should have a unique number so that it can be easily identified and found. Imagine that without this number, finding the one you need in thousands of product lists is like looking for a needle in a haystack.

2.Item number

This is the number of each component in the BOM, which helps us quickly locate specific items. Item numbers are like the pages of a book, making it easy for us to find specific information.

3.Part Name

Clear and concise part names are essential. Only in this way can we ensure that everyone knows what is needed and there is no confusion. For example, a description like “Screw M4x10” is very specific.

4.Specifications and Descriptions

Specifications and descriptions detail the size, material, and other technical parameters of the part. This information helps ensure that the selected parts meet the design requirements and there will be no assembly problems caused by non-conformance with specifications.


This refers to the number of each part required in the product. Accurate quantity information can help us control inventory and avoid waste.

6.Supplier Information

Sometimes, the BOM also includes recommended supplier information so that purchasing personnel can quickly find the right supplier to ensure the quality and delivery time of the parts.


Units (such as pieces, meters, kilograms, etc.) are the basic units for describing the quantity of parts. Clear units can avoid misunderstandings in quantity.

Table example

To show a typical BOM more intuitively, we can refer to the following table example:

Item Number Parts Name Specifications and Description quantity unit supplier Remark
001 Screw M4x10 4mm diameter, 10mm length, galvanized 50 pcs ABC supplier Used for housing fixing
002 Resistor 1kΩ 1/4W, 1% tolerance 100 pcs XYZ electronic components Circuit board assembly
003 Capacitor 10uF 16V, electrolytic capacitor 50 pcs Electronics City supplier Power supply filtering
004 PCB circuit board Double-layer board, 100x100mm 10 pcs Local PCB manufacturer Circuit connection carrier
005 Housing plastic parts ABS material, black, 200x100mm 10 pcs Plastic mold manufacturer External protection

This table clearly shows the specific information of each component, allowing all relevant personnel to quickly find the required information, thereby improving work efficiency and accuracy.

What is BOM in PCB design?

Design communication

BOM plays a bridging role in design communication. Designers need to communicate with other departments through BOM to ensure that the design intent is correctly understood and executed. Imagine that without BOM, designers may need to spend a lot of time explaining the purpose and installation method of each component.

Through BOM, designers can clearly communicate the specifications, quantity and installation location of each component. This not only improves work efficiency, but also reduces the risk of communication errors. For example, when designing a new electronic device, designers can clearly state which resistors, capacitors and chips are needed through BOM, so that engineers and purchasing staff can prepare and purchase according to the list.

Cost accounting

BOM is also an indispensable tool in cost accounting. By listing all the components and their quantities in detail, we can accurately calculate the material cost of the product. Cost accounting is not only to control expenses, but also to formulate reasonable selling prices and budgets.

With BOM, we can clearly see the cost of each component, so as to analyze which parts can be optimized and which parts can be replaced with more economical solutions. For example, if we find that the cost of a certain component is too high, we can try to find a substitute or negotiate with suppliers for a more favorable price.

In addition, BOM can also help us predict and control production costs. Before mass production, we can use BOM to conduct cost analysis to ensure that every link in the production process is within the budget.


BOM plays the role of a compass in procurement. According to BOM, procurement personnel can clearly know which parts and quantities need to be purchased. This not only improves procurement efficiency, but also ensures the quality and consistency of parts.

Through BOM, procurement personnel can quickly find the supplier information of the required parts, thus saving time in finding suppliers. It is also possible to ensure that the purchased parts meet the design requirements through the specifications and descriptions of BOM, avoiding returns and re-purchases due to non-conformance of specifications.

In addition, BOM can also help procurement personnel with inventory management. You can know which parts need to be stocked and which parts can be purchased on demand, thereby optimizing inventory levels and reducing inventory costs.

Supply Chain

In supply chain management, BOM also plays an important role. It can also realize visual management of the supply chain to ensure that every link can proceed as planned.

First, BOM can help us plan and coordinate the supply chain. You can know the delivery time of each component, so as to formulate a reasonable production plan and avoid production line shutdowns due to shortage of components.

Second, BOM can also help us with supply chain risk management. By analyzing the BOM, we can identify which parts are critical parts and which parts have higher supply chain risks, so as to take corresponding preventive measures. For example, for critical parts, we can choose multiple suppliers to reduce supply chain risks.

Finally, BOM can also help us optimize the supply chain. It can analyze which parts have higher supply chain costs and find optimization solutions. For example, the purchase price can be reduced through negotiation, or the logistics cost can be reduced by optimizing the transportation method.


In general, the bill of materials (BOM) plays a vital role in product design, manufacturing, cost accounting, procurement and supply chain management. It is not only a detailed list of parts, but also an important tool for our communication, coordination and management. Whether it is a designer, a purchaser or a supply chain manager, BOM is an indispensable part of their work. Through effective BOM management, we can improve work efficiency, reduce costs, ensure product quality, and ultimately achieve sustainable development of the enterprise.We have a more professional design team. If you need BOM design, please contact us.