A Bill of Materials (BOM) is a structured list of every component, part, subassembly, raw material, and quantity needed to build a medical device. In MedTech, it ties each item to specifications, suppliers, and revision history, forming a controlled record that supports manufacturing, traceability, and regulatory submissions under ISO 13485 and FDA 21 CFR Part 820.
What is a Bill of Materials (BOM)?
A Bill of Materials (BOM) is the master parts list for a product. For a medical device, it records each item by part number, description, quantity, unit of measure, and reference designator, along with the supplier and the approved revision. The BOM sits at the center of design outputs and feeds purchasing, production, inventory, and the Device Master Record (DMR).
Most teams keep more than one view of the same data. An engineering BOM (eBOM) reflects the design as drawn, organized by function. A manufacturing BOM (mBOM) reflects how the device is built, including consumables, packaging, and assembly sequence. Aligning the two views is a core discipline in regulated production.
Why Bill of Materials (BOM) matters in medical device development
A wrong part on a BOM can reach a patient. Substituting an uncontrolled resistor, an off-spec adhesive, or a different polymer grade can change electrical safety, biocompatibility, or sterilization behavior. That is why the BOM is a controlled document, not a spreadsheet anyone can edit.
Auditors treat the BOM as evidence. During an ISO 13485 or FDA inspection, investigators trace a finished unit back through its device history record to the BOM and the purchasing records behind it. Gaps or mismatches signal weak design controls and invite findings.
Cost and schedule ride on it too. An incomplete BOM stalls procurement and delays submissions, and a single-sourced critical part with no qualified alternate becomes a supply risk at the worst time.
Key components of a medical device BOM
A complete BOM usually captures:
- Part number and revision for every item, including subassemblies, so each version is uniquely identifiable.
- Description and specification linking to the controlled drawing or datasheet.
- Quantity and unit of measure at each assembly level.
- Reference designators for electronic components on a PCBA.
- Supplier and manufacturer part numbers, with approved alternates where qualified.
- Procurement data, including lead time and lifecycle status.
- Compliance attributes such as RoHS, REACH/SVHC, and material certifications.
The BOM is multi-level: the device, its subassemblies, and components nest in a hierarchy. Several standards shape how it is managed. Design control clauses in FDA 21 CFR Part 820.30 and ISO 13485 require BOM items to trace back to design outputs and to sit under change control. EU MDR 2017/745 expects component traceability and, for many devices, UDI data tied to the released configuration. For software-containing devices, IEC 62304 brings a parallel idea: a software bill of materials (SBOM) listing libraries and dependencies for cybersecurity and maintenance.
Common challenges and best practices
The most common failure is drift between the eBOM and mBOM after a design change. Engineering updates a component, the floor keeps building to the old list, and two records now disagree. Tie every BOM revision to formal change control (ECR/ECO), so no change reaches production without review and a clear effective date.
Placeholder parts are another trap. “TBD” entries that never get resolved block procurement and hide risk. Close out every line before design transfer.
Single sourcing on critical components looks fine until the supplier discontinues the part. Qualify alternates early and track lifecycle status so obsolescence does not force an unplanned redesign. Keep compliance data on the BOM itself rather than in scattered emails, because auditors and customers will ask for it.
Strong BOM management lives in a PLM or ERP system with role-based access, not a shared spreadsheet. Version everything, restrict edit rights, and make the released BOM the single source of truth.
How SJML helps with Bill of Materials (BOM)
SJML manages the Bill of Materials across design and manufacturing as part of its end-to-end CDMO work. During design transfer, its engineering teams build and review BOMs alongside DfX and NPI readiness checks, with items placed under structured change control. On the supply side, SJML supports supplier qualification, dual sourcing, and obsolescence management, backed by an SAP-integrated MES for component-level traceability. Compliance attributes such as RoHS and REACH/SVHC sit within its QARA practice, keeping engineering and manufacturing BOMs aligned from prototype through volume production.
Talk to SJML’s engineering team →
Frequently asked questions
An engineering BOM (eBOM) lists parts as the design defines them, grouped by function and tied to drawings. A manufacturing BOM (mBOM) lists what the factory actually consumes to build the device, including packaging, consumables, and assembly steps. Both describe the same product, but mismatches between them cause build errors, so teams keep the two synchronized through change control.
Yes. Under ISO 13485 and FDA 21 CFR Part 820, the BOM is part of design outputs and the Device Master Record, so it must be reviewed, approved, version-controlled, and changed only through documented change control. Auditors trace finished devices back to the released BOM, which makes its accuracy and revision history part of your compliance evidence.
A software bill of materials (SBOM) lists the software components, libraries, and dependencies inside a device. It complements the hardware BOM and supports IEC 62304 lifecycle management and cybersecurity. Regulators increasingly expect an SBOM for connected and software-containing devices, so that vulnerabilities in third-party code can be tracked and patched over the product’s life.
The BOM drives most of a device’s direct cost and much of its supply risk. Accurate quantities prevent over-purchasing, qualified alternates avoid line stoppages, and early obsolescence tracking prevents costly redesigns. Value engineering on the BOM, done without compromising verified specifications, is one of the main levers for reducing total cost of ownership.
Related terms
- Design Transfer
- Device Master Record (DMR)
- Design Controls
- Change Control
- Obsolescence Management
