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What is a BoM file and how to generate it

BoM is a word very used in electronics. It is the acronym of Bill of Materials and it is a list with all the components and detailed information of them, that compose an electronic and that are required to build the products.

It is very useful to provide the correct information about the components that will be soldered in a PCB and to have a record of all the components that are required to be procured or used from an internal inventory. It also provides a calculation of the cost of the product. Although the BoM can be generated manually, this would a very tedious work and all the main PCB design sofware allows to generate this BoM from all the components you are using in your design. For this purpose, all the components have to be correctly defined in your tool.

Typically, the BoM is generated in excel format like .xls or .csv and typical information they provide is:

  • The manufacturer part numbers of the components
  • The supplier part numbers, that sometimes is different to the manufacturer ones
  • Number of units required per part number
  • The price of each component
  • A small description of the component
  • The type of package
  • Placement method, you can indicate if it is SMD, feedthrough or die attach.
  • Layer in which the component will be placed, top or bottom.
  • Manufacturer/supplier of each component
  • Location of the component in the facilities of the product manufacturer 
  • The component reference designations that relates each component with the position in the layout of the printed circuit board. This is very useful for assembly services to know where all the components are located in the PCB. These designators are typically denoted with a letter, depending on the components (L for inductors, C for capacitors, R for resistors, D for diodes, T for transistors and U for other integrated circuits) and a number depending on how many components of each type are present in the PCB.

 

Below some description of how to export the BoM from the main PCBs design software in the market is shown.

 

Altium Designer 2018

Altium Designer is a powerful tool that allows you to generate a customized BoM. To generate the BoM this design software uses a tool named Report Manager. The BoM can be generated from two different ways, from the project source documents or from the active PCB document.

Generate Bill of Materials in Altium Designer. Source: https://www.altium.com/documentation/15.1/display/ADES/((Bill+of+Materials+(BOM)+))_AD
Generate Bill of Materials in Altium Designer.
Source: https://www.altium.com/documentation/15.1/display/ADES/((Bill+of+Materials+(BOM)+))_AD

 

To create it, you will have to select the tab Report and then select the Bill of Materials command from the Schematic or PCB editor. It will appear a dialog where you will see all the components and the associated parameters. You will be able to select the parameters you want to be included in your BoM file.

 

Autodesk Eagle

Eagle allows you to create BoM reports in an easy way. It can be done in two different ways, first one is using Eagle’s user language programs (ULPs) and the second one is using the Make Feature included in latest versions.

To create the report with a ULP you will have to go to the control panel, select the ULP tool and select the BOM.ulp from the available list. It will create a BoM from the components placed in your schematic design. You will be able to select the format of the file you will generate and the information you want to export.

Generate Bill of Materials in Autodesk Eagle. Source: https://www.autodesk.com/products/eagle/blog/creating-bom-pcb-manufacturing-basics-2/
Generate Bill of Materials in Autodesk Eagle.
Source: https://www.autodesk.com/products/eagle/blog/creating-bom-pcb-manufacturing-basics-2/

 

The Make Feature tool makes easy the generation of BoM files. You will be able to create it from the PCB layout window, selecting the button Make. A dialog will appear where you will be able to select the name of the project to load. Once the project is loaded you can push the Bill of Materials icon. The BoM will appear in your display and you will be able to download it by pressing the Download BOM button.

 

KiCad

KiCad allows the user to generate a BoM in two different manners, from the schematic and from the PCB layout. When you do it from the layout, the generation is very simple but it has some limitations. On the other hand, when it is done from the schematic, although it is some more complex, you will have all the options enabled.

To create the report from the layout (PCBnew) in KiCad, you will have to select File > Fabrication output >  BOM. You will have to select the location where you will place the report and the name of the file. The report will include all parameter values grouped by value. Different plugins can be used to export the information you need in your BoM.

Generate Bill of Materials in KiCad. Source: http://kicad-pcb.org/discover/eeschema/
Generate Bill of Materials in KiCad.
Source: http://kicad-pcb.org/discover/eeschema/

 

To create the report from the schematic (EEschema in KiCad) you will need to use a plugin. Each plugin allows you to generate different reports types with more or less information. It has one by default but other ones can be downloaded to obtain the report you need. When you want to create your BoM report, you will have to select the plugin you want to use and press the Generate button. You can generate it in html but also in csv format.

 

Mentor Graphics pads

In Mentor Graphics you can export your BoM selecting the corresponding tab in your project and selecting the information you want to add to your BoM report. Once all the information is selected you can export the report.

Generate Bill of Materials in Menthor Graphics pads. Source: https://www.pads.com/multimedia/overview/generate-costed-boms-at-any-time-20e02c54-6452-4975-9b40-b4a966021100
Generate Bill of Materials in Menthor Graphics pads.
Source: https://www.pads.com/multimedia/overview/generate-costed-boms-at-any-time-20e02c54-6452-4975-9b40-b4a966021100

 

You can also do this task by selecting the tab Output and then Bill of Materials. There you can customize the raws and columns and additional information you want to add to the final report. Previous information can depend on the version you are using.

 

Cadence OrCad

The way to create the BoM in Cadence Orcad can vary depending on the version you are using. 
In last versions the way to export the BoM is selecting in the tab Tools from the menu and then select Bill of Materials. Then, the Bill of Materials dialog will display. There you can customize the information you will have to export to your report and export it in CSV. Once it is exported you can see it in the text editor of the software or using Excel.

Generate Bill of Materials in Cadence OrCAD.
Generate Bill of Materials in Cadence OrCAD.

 

DipTrace

Diptrace has also a BoM feature that allows the user to generate BoM reports in CSV format, customizing the rows and columns, and all the information that will be exported.
To generate the report, you will have to go to the DipTrace Schematic, then select Objects\Bill of Materials from the main Menu. In this part, you can select the information you want to generate in your report.

Generate Bill of Materials in Diptrace. Source: https://diptrace.com/books/tutorial.pdf
Generate Bill of Materials in Diptrace.
Source: https://diptrace.com/books/tutorial.pdf

 

Independently on the tool you have used to generate your BoM report you will have to provide also a CPL file with all the information required to assembly your PCBs. In the next post, detailed information about what is a CPL file and how to generate it in the main PCB design tools will be explained.

 Roberto
 2019-01-03 09:08
 Help    Engineering   
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