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Home > News > Company News > Maintain your bill of material.....

Maintain your bill of materials

  • Author:Ella Cai
  • Release on:2017-09-21
It pays to invest time to maintain your bill of materials as a design progresses, writes Leigh Gawne.

Proper bill‑of‑materials (BOM) management is crucial to electronics design realisation, but even if it is well executed, issues can come up that will prevent designs from moving through the manufacturing stage.

Bringing an idea from design to physical product can be extremely difficult, with problems cropping up from the beginning of the design stage to the final product. When this happens deadlines are not met and features do not work as planned.

There are many causes for such delays, but one of the main ones (and perhaps one of the simplest fixes) occurs when a design is ready to go to PCB assembly. Here, one of the biggest challenges is making sure you have a manufacturable BOM, and are keeping it manufacturable throughout the life of the product.
Managing your bill of materials

The BOM connects the design, manufacturing, and supply chain domains. Though many consider it to be just another output from the design process that is passed along, the BOM contains – or should contain – enough information to reflect what is in the design.

A BOM that is formed from an electronic computer-aided design (CAD) process, for instance, is often sufficient to properly represent the design intent, though it does not always enable the product to be produced.

Unfortunately, it may also contain ambiguities, or worse still, errors, when it comes to purchasing the parts that you need. Missing, partial, or incorrect part numbers can result in countless emails and phone calls with the contract manufacturer before you can even attempt to order all the parts you need.

It is crucial that the bill of materials be maintained. One way you can do this is through using iterative cycles to resolve part number issues and identify the components that are no longer available.

Unfortunately, this activity takes time, and this lack of preventative maintenance of the BOM means that problems will occur at the last minute. However, when you effectively control your BOM, these problems can be dealt with much earlier in the design process.

Fortunately, there are many design realisation tools available to help. The parts needed for your electronics design can change over time.

The components you decide to use at the beginning of the design process may no longer be available by the time the design is ready for manufacture.

Also, changes to the design itself often mean the components originally planned in need to be swapped out if the design is to work properly – something that is often overlooked in the middle of a design.

Failure to document the changes and updates to a design’s parts causes problems once the design is ready to move on to the next stage in the production process. Issues with the supply chain can mean that the PCBs sent to manufacturing are not properly assembled, or certain parts are not assembled at all.

Imagine you have been meticulous with tracking your bill of materials. You work with manufacturing to resolve all BOM issues that come up, and now your product is ready to assemble. But then you learn there is a problem on the assembly line.

You have a quad-flat no‑leads (QFN) footprint in your design for the USB hub IC, but the reel that has been delivered contains the thin-shrink small outline package (TSSOP) variant because the part number your BOM specified was the TSSOP variant, not the QFN variant you used in your design.

This is a single-letter mistake in the suffix that will mean that your part must be left off.

Dealing with discontinuity

Everything may fit seamlessly inside the design environment, but once you leave the design environment, things change, and not always in a good way.

Disorganised Excel spreadsheets, lengthy Google docs, and long chains of emails between members of different teams make the post-design process a nightmare, and the BOM a tangled mess.

You might share a file‑based document, but you can never be completely certain that the version others are using is up-to-date. This can mean that the critical details needed to make the design work might not be properly communicated.

One way to ensure that this critical design information makes it through to the next stage intact is to use the right tools to manage your BOM.

In successful electronics production there are many setbacks that must be dealt with, but there is no silver bullet for all of them. Fortunately, there are many different solutions and tools available to ensure that these setbacks are quickly resolved, or avoided altogether.

Leveraging data as part of automated checks ensures continuity and the flow of information between design, manufacture and supply chain domains. Having the right information goes a long way to mitigate the risks involved and prevent them from recurring.

There are many tools to help with bill of materials management – one such tool is Ciiva. These solutions allow you to easily select, verify and manage your parts to ensure a manufacturable BOM.