Bill of materials

What is the bill of materials and its different markings?

A bill of material is a list of all the components, sub components, parts, assemblies and other equipment needed to manufacture the end product. Many industries need to generate BOM for expert analysis before manufacturing the final product. So a BOM can be of 3 different types.

  • Engineering BOM
  • Sales BOM
  • Manufacturing BOM

The components in all these can change based on the analysis. During engineering BOM is done during development stages in which all the components needed are included in an excel sheet. Sales BOM is when purchasers are buying the components and they can make slight changes to the BOM depending on the availability of the components. Manufacturing BOM is the final excel sheet which has all the optimisation done to reduce the cost of the final product and also to redesign the engineering work if a particular component has shortage of supply. So care must be taken by designers to make sure that the components have steady supply and that they will not have an end of supply in near future while also considering the cost.

Many industries generate a BOM file for every new product. These can be automobiles, technology development, pcb manufacturing, construction, warehouse, and many more. There are important fields in the BOM. Some of the fields indicated that DNP which means the sales person need not buy such components from the BOM. and some are TP there are also the components that need not be purchased. Some rows indicate alternate components which means the seller has a choice to either components1 if it is not available for some reason then they can buy component2 since both have the same footprint and serve the same purpose of the job.

Most of the designers use certain tools to generate this BOM file. Many cad designing, pcb designing tools like 

  • Orcad.
  • Altium Designer.
  • Autodesk EAGLE.
  • KiCad EDA.
  • SolidWorks PCB.
  • OrCAD Capture.
  • ExpressPCB Plus.
  • DipTrace.

How to generate a BOM?

Many tools have different options to generate a BOM file. A BOM should include at least these details.

  • Part number
  • Manufacturer name
  • Description
  • Quantity
  • Procurement type
  • Flexibility indicator
  • Alternate parts
  • BOM level
  • Supporting files
  • Reference designator
  • Package type
  • Placement method
  • Board layer
  • Phase
  • Comments and notes

You can create one from the menu using the following options in most of the tools but some tools have a different option based on native language and convenience.

Manufacturing -> Master Data -> Bill of Materials -> Create

Sample bill of materials.

Most BOM contains per row for a component these values so it will be easy to analyse and mark if some of the components have a shortage or supply or something else.

  • Reference
  • Part Number
  • Manufacturer
  • Description
  • Pop Option

A sample BOM table is shown below and can vary depending on the tool used to generate the file.

ItemQuantityReferencePartPCB Footprint





241FB100.1 OhmFB_0805


The second part of the same BOM file is as shown below.

DescriptionManufacturerManufacturer PNDNI
CONN PCI EXP MINI FEMALE 52POSTE Connectivity AMP Connectors1775838-2
CAP CER 10UF 16V X5R 0805Murata Electronics North AmericaGRM21BR61C106KE15L
CAP CER 0.1UF 16V X7R 0402Murata Electronics North AmericaGRM155R71C104KA88J
CAP CER 2.2UF 6.3V X5R 0402TDKC1005X5R0J225K050BC
CAP CER 470PF 50V X7R 0402YageoCC0402KRX7R9BB471
CAP CER 18PF 50V C0G 0402TDKC1005C0G1H180J050BA
CAP CER 1000PF 16V X7R 0402YageoCC0402KRX7R7BB102
CAP ALUM POLY 100UF 20% 6.3V SMDPanasonic Electronic Components6SVP100M
CAP CER 1UF 6.3V X5R 0402TDKC1005X5R0J105K050BB
CAP CER 0.022UF 10V X7R 0402Tayo YudenLMK105B7223KV-F
CAP CER 30PF 50V NP0 0402KemetC0402C300J5GACTU
CAP CER 4.7UF 6.3V 20% X5R 0402MURATAGRM155R60J475ME47D
CAP CER 10000PF 16V X7R 0402Murata Electronics North AmericaGRM155R71C103KA01D
CAP CER 22UF 16V X6S 0805TDK CorporationC2012X6S1C226M125AC
CAP CER 47PF 50V NP0 0402TDK CorporationCGA2B2NP01H470J050BA
CAP CER 15PF 50V NP0 0402Johanson Technology Inc.500R07S150GV4TDNI
CAP CER 2200PF 50V X7R 0402AVX Corporation04025C222KAT2A
CAP CER 0.22UF 50V X5R 0402Taiyo YudenUMK105BJ224KV-F
DIODE GEN PURP 100V 200MA DO35ON Semiconductor1N4148
FERRITE 800MA 150 OHM 0805 SMDStewardLI0805H151R-10
FIXED IND 1UH 4.3A 42 MOHM SMDMurata Electronics North AmericaDFE252012P-1R0M=P2
RES SMD 0.1 OHM 5% 1/8W 0805CTS Resistor Products73L3R10J
CONN HEADER .100 SINGL R/A 6POSSullins Connector SolutionsPEC06SBAN