PCB Tech - Bill of materials is important in the PCB manufacturing process

The importance of efficient production planning cannot be underestimated because it goes a long way in optimizing production and balancing production lines. Therefore, the hourly demand is a powerful design data, including PCB layout data, bill of materials, usually called BoM, and product references.

Why the bill of materials is important in the PCB manufacturing process

In fact, the entire SMT manufacturing process is driven by BoM. This is because the function of the PCB depends on the components listed in the BoM. In turn, using the correct components is critical to the function of the PCB. Therefore, any PCB assembly order needs to be initiated using the bill of materials. BoM not only contains a list of components, but also their location on the printed circuit board. In turn, BoM allows sourcing experts to find suitable distributors for components, while looking for cost-effective price points. Some components may not be available, so it provides an opportunity for procurement experts to find alternative distributors so that they can work seamlessly.

Detailed BoM, which contains specifications related to the item number, description of parts, manufacturer's name, quantity, etc., so it is very convenient. This not only ensures the quality, but also ensures that the PCB manufacturer can follow the delivery deadline without any hiccups. In the case of turnkey components, the names and details of the distributor and manufacturer must also be mentioned. In fact, multiple dealer names can help the procurement process and ensure that no time is wasted if a particular dealer does not have parts readily available.

The optimized component list allows a well-assembled plan and clearly planned scheduling steps. This in turn ensures zero error in PCB production. On the other hand, the lack of an effective BoM may mean a large number of revisions, which will eventually lead to delays in delivery.

The manufacturer usually provides a template for the sample BoM so that all necessary information is captured, so there is no room for ambiguity. BoM also often includes support for explosions and implosions. Although explosion refers to the components of the display assembly, implosion helps to see where a particular part is used and to determine which parts are associated with any risky parts. Therefore, the hierarchical BoM can easily study the entire structure.

When creating a BoM, you need to pay special attention to the following aspects:

1 Very thorough-Ideally, BoM should help manufacturers create PCBs from scratch. If you have received the BoM template from the manufacturer, please make sure you spend enough time to complete it and provide all the necessary details.

2 Point out where you can allow flexibility-it may be important that some parts may exist where you want the manufacturer to strictly adhere to the approved supplier list. Although there may be other non-critical factors, it can be optimized for cost. It is best to clearly state this in the BoM so that time is not wasted in unnecessary revisions, or worse, you may encounter procurement errors that may cause you to pay a heavy price.

3 Make sure parts are available-When listing parts in BoM, a quick check to see if parts are readily available will greatly help ensure seamless production. If you ignore this step, you will usually make expensive design decisions at a later stage.

4 Determine how many levels of BoM need-it is important to determine whether the BoM should be single-level or multi-level. Generally, single-level BoM is suitable for places where you are looking for lean or pull manufacturing. In addition, it is recommended to use when the manufacturer does not need the overall structure of the product design. On the other hand, multi-level BoM is related, you can share part of BoM with the manufacturer, and the location where you can copy sub-components to other products. You need to determine the level of detail required for the multi-level BoM and drill down accordingly.

5 Document changes-From the prototype stage to the actual generated BoM may change, these changes need to be recorded. It is best to keep all change logs and history of various versions so that everyone not only synchronizes with the changes, but also synchronizes with the changes that caused them.

Treating the bill of materials as your shopping list. Going out without it can lead to inadvertent omissions and costly mistakes. The rule of thumb is obviously to fully evaluate your needs and build a BoM around it.