BOM Checklist for OEMs Partnering with EMS Providers
Partnering with an EMS provider for electro-mechanical assembly and box build requires OEMs to look beyond simply handing off a bill of materials (BOM). To ensure a successful, value-driven relationship, OEMs must consider a range of strategic, technical, and operational factors that impact viability, cost, quality, and time-to-market.
This discussion provides a comprehensive checklist to guide OEMs through the critical elements of BOM management and collaboration with EMS partners, helping to optimize production efficiency, mitigate risks, and accelerate product success in today’s complex manufacturing landscape.
BOM Checklist for OEMs Partnering with EMS Providers
When partnering with an EMS provider for electro-mechanical assembly and box build, OEMs should consider more than the basics of BOM handoff and examine a range of strategic, technical, and operational factors to ensure a successful, value-driven relationship.
Here’s what you need to know:
- Detailed Documentation and Data Sharing
- Comprehensive BOM: Provide a current, complete, accurate, rev-controlled BOM with clearly defined manufacturer and manufacturer part number information, approved vendor list information, and any approved alternates. Be sure to identify any non-critical materials that equivalents may be used for—such as heat-shrink tubing, tie wraps, labels, etc.—that your EMS partner may have open stock for. Your chosen EMS partner will be able to leverage their existing open stock components that can eliminate or reduce your stock/MOQ exposure while still meeting your design objectives.
- Supporting Files: Share current, rev-controlled CAD data, schematics, Gerbers, assembly and sub-assembly drawings, test requirements, packaging specs, etc.
- Design for Manufacturability (DFM): Choose an EMS partner that doesn’t just “build-to-print” but proactively reviews your BOM and design files, verifying component compatibility, suitability for intended use, offering DFM feedback and suggesting improvements (such as the implementation of logical sub-assembly hierarchy) to reduce costs, improve manufacturability and operator comprehension, increase efficiency, and speed up time-to-market.
One such obvious example would be for your EMS partner to suggest and transition from customer-specified hand-crimped terminals to compatible terminals that they may have open stock of—to avoid long lead times and large minimum order quantities, and therefore, eliminate or reduce your inventory liability, that can be crimped on applicators that they have in their tooling arsenal. This reduces labor and operator fatigue—increasing overall quality, reliability, efficiency, ultimately lowering your cost and tooling exposure.
- EMS Partner Selection Criteria
- Technical Alignment: Ensure the EMS provider’s technical capabilities, certifications (ISO, IPC, UL, ITAR, C-TPAT, etc.), and business profile (core competencies and expertise, QMS, automation, capacity, scalability, supply chain proficiency, etc.) align with your current and future objectives and industry standards.
- Process Transparency: Look for a partner willing to walk you through their processes—administrative, documentation, ERP/MRP, QMS, production, quality control, test, supply chain, ECO management, etc.
- Cultural Fit: Evaluate the prospective EMS partner’s communication style, responsiveness, and willingness to collaborate. A strong cultural and personality match can make a significant difference in long-term success.
- Supply Chain & Procurement Strategy
- Component Sourcing: EMS providers with established supplier networks can often secure better pricing, terms, and lead times for BOM components, including risk buys on scarce or long-lead items.
- Inventory Management: Clarify who owns inventory at each stage (raw materials and pipeline, WIP, finished goods), and define responsibilities for excess or obsolete stock. The implementation of a MSA (master service agreement) is an excellent approach—establishing mutually agreed terms & conditions and responsibilities of both parties.
- Supply Chain, Manufacturing Resilience & Scalability:
Ask a prospective EMS partner about their ability and proficiency to:
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- Multi-source
- Manage shortages
- Proactively anticipate, adapt to, and manage supply chain disruptions
- Identify suitable alternate components
- Scale production to meet demand
- Transition to lower cost region manufacturing if required—based on future pricing objectives or point-of-consumption at scale
- Support a hybrid manufacturing model whereby certain sub-assemblies are manufactured in a lower cost region and integrated locally to support future price reduction initiatives while maintaining final assembly locally
- Support fulfillment models
- Manage logistics
- Program Launch & Change Management
- NPI Involvement: Involve the EMS provider early in new product development (NPD) and new product introduction (NPI) for smoother ramp-up, enhanced DFM input, and faster troubleshooting of BOM or design issues.
- Engineering Change Orders (ECOs): Establish clear protocols for handling design and BOM changes, substitutions, and documentation updates throughout the product lifecycle.
- Ongoing Collaboration: Maintain regular communication, operational reviews, and feedback loops to address issues that arise, optimize the BOM, and capture cost-saving opportunities and efficiency gains as the program matures.
- Quality, Testing, and Compliance
- Quality Management System: Confirm the EMS provider’s QMS covers all aspects of BOM management, traceability, and regulatory compliance.
- Testing & Validation: Ensure the EMS partner has robust in-process and final testing capabilities and methodology aligned with your current and future requirements and objectives.
- Certifications: Verify that the EMS provider’s certifications match your company’s requisite certifications and market regulatory needs:
- ISO 9001
- ISO 13485 for medical device
- IPC-A-620: Workmanship requirements and acceptance standards for cable assemblies & wire harnesses
- IPC-610: Workmanship requirements and acceptance standards for electronic assemblies
- ITAR (International Traffic in Arms Regulations)—safeguarding U.S. security and restricting access to sensitive military technologies
- C-TPAT (Customs-Trade Partnership Against Terrorism)—Enhancement of international supply chain security
- Risk Mitigation & Flexibility
- Forecast Variability: Discuss how the EMS provider handles demand swings, risk buys, and buffer stock for critical BOM items.
- Scalability: Assess their ability to ramp production and support high-mix/low-volume as well as high-volume programs as your needs evolve.
- Crisis Response: Ensure the EMS partner has a suitable disaster plan in place. Establish plans for managing shortages, recalls, or sudden changes in BOM content availability.
- Total Cost and Overall Value
- Total Cost of Acquisition: Look beyond unit price—factor in lead times, MOQs & MRQs, shipping costs, production flexibility, supply chain flexibility and management, quality, and the EMS partner’s ability to reduce your internal costs and accelerate time-to-market.
- Contract Clarity: Define lead times, minimum order and release quantities, inventory responsibilities, and escalation procedures in your contract to avoid surprises and maintain alignment.
A successful OEM-EMS partnership for electro-mechanical assembly and box builds hinge on thorough BOM and documentation data sharing, proactive DFM collaboration, robust supply chain management, and clear communication protocols. By selecting an EMS partner that offers technical expertise, transparency, flexibility, a strong and resilient supply chain, and a world-class quality culture, OEMs can optimize costs, reduce risks, and accelerate product success in today’s complex manufacturing landscape.
OEM-EMS Partnership Checklist Recap:
1. Detailed Documentation and Data Sharing:
- Provide a complete BOM with clear and accurate manufacturer part numbers, approved vendor lists, and qualified alternates
- Share current, rev-controlled CAD files, Gerbers, schematics, assembly drawings, and test requirements
- Choose an EMS partner that offers proactive DFM and process optimization feedback to improve manufacturability, efficiency, and reduce costs.
- Verify that the EMS partner can support the needed tooling and your objectives thereof.
2. EMS Partner Selection Criteria
- Ensure technical capabilities and certifications align with your current and future company and product objectives.
- Look for transparency in processes and a cultural fit for effective collaboration.
3. Supply Chain & Procurement Strategy
- Leverage EMS providers’ supplier networks for better pricing, terms, and lead times.
- Clarify inventory ownership and assess supply chain effectiveness and resilience.
4. Program Launch & Change Management
- Involve EMS provider early in new product development and introduction for smoother ramp-up.
- Establish clear protocols for engineering change orders and maintain ongoing collaboration.
5. Quality, Testing, and Compliance
- Confirm EMS provider’s quality management system covers BOM management and required regulatory compliance.
- Provide required testing criteria and confirm compliance.
6. Risk Mitigation & Flexibility
- Discuss how the EMS provider handles demand variability, scalability, and crisis response plans for shortages or recalls.
7. Cost and Total Value
- Consider total landed cost of acquisition—beyond unit price, including MOQs/MRQs, shipping costs, responsiveness, lead times, flexibility, and supply chain management.
- Define contract terms clearly to avoid surprises.
When you follow this checklist, you’ll build stronger, more resilient partnerships with your EMS providers—ensuring smoother production, better risk management, and greater long-term value from every electro-mechanical assembly and box build project.
We’d love to have this discussion with you so we can check off all your boxes. We look forward to talking with you about your next EMS project. Contact us to begin the conversation.
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