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On PCB BOM in PCB manufacturing and PCBA process

On PCB BOM in PCB manufacturing and PCBA process

BOM is one of the key points of manufacturing management. A simple definition is “a table that records the materials used in the composition of a product”. PCB production involves a variety of raw materials that need to be assembled before actual production begins. How to determine the raw material requirements for PCB and PCBA? The PCB BOM (Bill Of Material) is the answer. The PCB BOM list refers to the final specific PCB materials required in the PCBA process. The circuit board assembly company will purchase and assemble according to the BOM list provided by the customer. After the final PCBA testing is passed, the product will be sent to the customer.

A proper PCB component bill of materials enables you to know the exact components and materials you need, along with their brands, quantities, dimensions, and other details. This can greatly improve production efficiency and customer satisfaction for PCB and PCBA manufacturing, and improve the level of standardized management.

What is a PCB BOM?

What is a PCB BOMIn the context of PCB design, a PCB BOM is defined as a list of all the components needed during the process of manufacturing to build a certain PCB. In other words, it is a checklist of all the requirements, much like a recipe for making a product.

A PCB BOM will also offer instructions for procuring and using these things. A PCB BOM can serve as a central repository for the materials, components, and construction methods needed to manufacture a product because of the scope and depth of the data it collects.

How many types of PCB BOM are there?

BOMs can have a variety of shapes and forms. The following lists the primary three types:
1.Single-level BOM:
A single-level PCB BOM is a list of products that includes every assembly and the corresponding quantity needed to manufacture it. The relationship between components and subassemblies is not specified in this type of bill of materials, making it unsuitable for complex PCB assemblies. A single-level PCB BOM is insufficient to determine which component needs to be reimbursed or replaced in cases of product failure.

2.Multi-level BOM:
A multi-level bill of materials contains a list of the components, assemblies, and materials required to make a part (BOM). Every element that is either directly or indirectly used in a parent item is displayed. All of an item’s components, including purchased parts and raw ingredients, are displayed when it is a subcomponent, mix, intermediate, etc. Moreover, a tree can be used to represent the multiple levels in the structure of multi-level PCB BOM.

3.Flattened BOM:
A BOM that has been flattened eliminates the intermediate levels and joins the lowest level to the highest level. It’s a terrific way to view ALL part quantities along with their summed quantities, regardless of what level of the BOM they appear in.
How many types of PCB BOM are there
Besides, according to the purpose, the PCB BOM can be divided into
● Engineering BOM
● Manufacturing BOM
● Customer BOM
● Sale BOM
● Costing BOM

What are the parts of a bill of materials?

Following are main parts of a PCB BOM:
1.The BOM level.
2.MPN (Manufacturers part number)
3.Quantity and the measurement of the components.
5.Type of Procurement.
7.Plugin location

What is the use of BOM in the PCB assembly process?

From a PCB assembly standpoint, a BOM is a complete list of all items, parts, and raw materials required.The PCB BOM is crucial in the design and production phases of any electronic device, beginning with the printed circuit board (PCB). Without a thorough and well-organized BOM, the project can need multiple pointless modifications, leading to possible problems and production delays.
What is the use of BOM in the PCB assembly process
If your electronic components list is substandard, you may encounter manufacturing errors, mismatched parts, higher-than-expected costs, or operational delays. For example, one of the main problems with incomplete or poorly manufactured BOM is that some components may not fit on the PCB or in the wrong place. Sometimes it’s just a matter of adding missing components during rework. Not only will this delay delivery, but it will also increase costs.

If your BOM can’t tell the CM exactly where each part is on the board, some components may be swapped. In the best case, you may find and have the batch repaired by your manufacturer or run a new batch. In the worst case you get the order and test the PCB, but there will be premature failure of the board.

In a word, the PCB BOM is a key link, which involves various functional modules of the PCB, the soldering and testing of the final PCB, and the components of all relevant parameters and specifications of the crude PCB. It is an important part of PCB design and cloning.

How do you create a BOM?

The creation of a BOM can be divided into multiple steps. They are mentioned below:
● The initial draught of the document’s construction.
● Organization of the document for the identification of users and their rights of access.
● Identification of multiple columns for different categories.
● Filling and addition of rows with accurate information.
● Updating of BOM.

What is the difference between BOM and BOQ?

One of the systematic methods used in the construction industry is the Bill of Quantities (BOQ), the main purpose of which is to list the work items for comparison purposes and to form a reasonable agreement among the parties concerned for contractual activities. In contrast, the BOM process has a long list that contains the information and instructions needed to construct, manufacture, and repair a good or service. Both of these work together to improve planning and lower the possibility of mistakes.

What is the format of Bill of Material?

The BOM format is divided into various sections, for a better understanding of the materials used, the quantity, and the overall estimation.

1.Part number:
Each component or part has a unique identification number to help with identification.

2.Part name:
Each part or component has a unique name that helps the employee recognize the product. These given names make production easy and convenient.

The description in BOM gives the reader information about each part and makes it easier for them to identify between comparable pieces by color and size.

The number of parts or components required for a product’s overall construction will be listed in this column.

5.Measurement of Units:
The unit measurement of any good, part or raw material determines the singular entity of a given constituent.

6.The phase of the product:
The stages that establish the phases also make it easier to follow the product’s life cycle in real-time.

7.Designator of Reference:
If we consider the example of a PCB, this designator provides the production location of parts used in that PCB.

8.Comments and Notes of BOM:
Any additional information not included in the other BOM components that are needed to assemble the finished product is added in this section.

9.Priority analysis:
Users can prioritize purchases by knowing which elements are essential. As an illustration, components with larger dollar values and longer lead times might be given preference.

FAQs about PCB BOM

What is a BOM file in PCB design

What is a BOM file in PCB design?

The BOM file in PCB design gives you a list of every part you’ll need to assemble your printed circuit board. In other words, it’s a PCB design recipe!

It’s critical to produce an accurate BOM. If components are missing from your BOM, this might increase costs and cause delays because you would have to find the missing components or alternate sources.

What is BOM in SMT?

The PCB BOM is a file that provides a data format description of the product structure. The material name, quantity, and placement position number are all listed in the BOM for SMT processing. The BOM serves as a crucial foundation for the programming of placement machines and IPQC verification.

What is the BOM level?

Multiple layers are frequently present in a PCB BOM. The component’s position in the BOM hierarchy is indicated by the BOM level number. Also added and numbered nearer to completion than their parts are sub-assemblies.


Hence, no matter the size or complexity of the product, a well-designed PCB BOM is crucial for any manufacturing company since it not only facilitates the successful commercialization of the product but also serves as a crucial step in the product development process.



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