Introduction to Turnkey PCB Assembly

Turnkey PCB (printed circuit board) assembly refers to the complete end-to-end process of fabricating PCBs from design through final assembly by a single vendor. In a turnkey PCB Assembly service, the provider handles every step including:

• PCB design review and optimization
• Prototyping
• Component sourcing and procurement
• PCB Fabrication
• PCB assembly (PCBA)
• Testing and quality control
• Final packaging and shipping

Turnkey PCB assembly streamlines the complex process of PCB manufacturing by providing a one-stop shop solution. Clients simply provide the PCB design files, Bill of Materials (BOM), and documentation, and the turnkey provider takes care of the rest, delivering fully assembled and tested PCBs.

Benefits of Turnkey PCB Assembly

There are several key benefits to using a turnkey PCB assembly service:

1. Simplified Logistics – With turnkey, you only have to manage one vendor instead of coordinating between separate design, fabrication, and assembly providers. This greatly simplifies procurement, communication and logistics.

2. Faster Turnaround – Turnkey providers optimize the handoffs between each stage of PCB production, enabling faster overall turnaround times compared to using multiple vendors. Turnkey is ideal when you need PCBs manufactured as quickly as possible.

3. Cost Savings – Turnkey PCB services can source components and materials in volume leading to lower costs. They also minimize shipping costs between vendors.

4. Accountability – Since one vendor is responsible for the entire PCB build, it’s clear who is accountable if issues arise. There’s no finger pointing between suppliers.

5. Design for Manufacturability – Turnkey PCB providers review designs upfront and provide DFM feedback to optimize the PCB design and head off potential manufacturability issues early.

The Turnkey PCB Assembly Process

While the specific process can vary between turnkey PCBA vendors, it typically follows these general steps:

1. Design Review – The turnkey vendor reviews PCB design files, BOM, and manufacturing documentation and provides feedback on manufacturability.

2. Prototyping (Optional) – If requested, the turnkey supplier will produce PCB Prototype boards for testing and validation before moving to production.

3. Component Sourcing – Based on the BOM, the turnkey provider sources components from their vetted network of suppliers.

4. PCB Fabrication – The raw PCB boards are fabricated based on the design files using processes like etching, drilling, plating and silkscreen.

5. PCB Assembly – The components are assembled onto the fabricated PCB board using either through-hole (THT) or surface mount technology (SMT) soldering processes.

6. Testing and QA – Assembled PCBs go through various testing and inspection procedures based on IPC standards and client requirements to ensure quality. This can include automated optical inspection (AOI), X-ray, in-circuit testing (ICT), and functional circuit testing.

7. Final Packaging – The final assembled and tested PCB boards are packaged for protection during shipping. Packaging can range from simple antistatic bags to custom clamshell packaging.

8. Shipping and Delivery – The final PCBs are shipped to the client or end customer based on the agreed upon Incoterms and using the specified carriers and shipping methods.

Choosing a Turnkey PCB Assembly Partner

Selecting the right turnkey PCB assembly and manufacturing partner is critical to the success of your product. Key considerations include:

Technical Capabilities

Evaluate the technical manufacturing capabilities of potential turnkey partners:

• Manufacturing Technology – Do they have both SMT and THT lines? What type of pick and place and soldering equipment do they use? More advanced equipment generally translates to higher quality and repeatability.

• Component Sizes – Can they handle the component package sizes and pitches your design requires such as 0201 metric or ultra fine pitch BGAs?

• Board Complexity – Are they experienced in building complex Multilayer PCBs, flex circuits, HDI or other non-standard board structures your product needs?

• Special Processes – Some PCB builds may require niche manufacturing processes like gold finger edge contacts, press-fit pins, conformal coating, or encapsulation. Not all turnkey shops support these capabilities in-house.

Testing and Quality

Testing and quality assurance is a core part of turnkey PCBA services. The specific testing capabilities, certifications and quality processes a provider offers is an important consideration:

• Testing Equipment – What specific testing equipment and procedures does the provider use – for example for AOI, AXI, ICT and boundary scan? More extensive testing improves quality.

• Quality Certifications – Is the vendor certified to key quality management standards like ISO 9001, ISO 13485 (for medical), or IATF 16949 (automotive)? These certifications provide assurance of mature and compliant quality processes.

• IPC Standards – Does the vendor manufacture to IPC standards such as IPC-A-610 for manufacturing and J-STD-001 for soldering? These ensure use of industry standard quality criteria.

• First Pass Yield (FPY) – First Pass Yield is a metric of PCBA quality, measuring the percentage of boards that pass testing on the first attempt without needing any rework. Look for turnkey providers with high FPY rates.

Supply Chain and Logistics

A turnkey provider’s supply chain, inventory management, and logistics capabilities are important, especially for larger scale production:

• Supplier Network – An extensive network of qualified component suppliers helps ensure part availability and competitive pricing. This is especially valuable in times of component shortages or obsolescence.

• Inventory Management – Robust inventory management with kanban, JIT, and consignment models help ensure efficient material flow for production. The provider should use ERPs and MRPs to provide inventory tracking and traceability.

• Order Fulfillment – For builds that require direct shipment to end customers, evaluate the provider’s order fulfillment processes and whether they can drop ship on your behalf.

Communication and Support

Efficient communication and customer support can make or break a turnkey PCBA relationship. Assess potential partners on:

• Project Management – Will you have a dedicated project manager and team? How will they keep you updated on the status of your build? Look for a partner that assigns a single point of contact.

• Engineering Support – Access to knowledgeable application and manufacturing engineers for DFM guidance, yield enhancement and troubleshooting is invaluable.

• Reporting and Data Access – The turnkey vendor should provide regular status reports and access to production and testing data for traceability.

Company Profile

Finally, evaluate the overall background and market presence of the turnkey provider:

• Financial Stability – Is the company financially stable with a healthy balance sheet? This is important for assurance of long term support.

• Industry Experience – How long have they been in the PCB assembly business? Do they have experience serving your specific industry and product type?

• Manufacturing Locations – Consider whether the company has manufacturing locations that align with your regional requirements for product origin, tariffs, or shipping lanes. Having multiple locations provides beneficial supply chain redundancy.

• Reputation – Look at reviews and seek references from customers to gauge the reputation of the provider for quality, reliability, and service.

Turnkey PCB Assembly vs. EMS

Turnkey PCB assembly is often used interchangeably with EMS (Electronics Manufacturing Services), but there are some key differences. Turnkey PCBA typically focuses solely on assembling the PCB itself and providing the bare board. However, full service EMS providers offer a broader set of capabilities beyond PCBA:

Box Builds

EMS providers can build the full product, not just the PCBA. They procure the enclosures, cables, packaging and other components beyond the PCB BOM and integrate them into the final product build.

Electromechanical Assembly

Many electronics products require integration of electromechanical elements like connectors, belts, fans, motors and more. EMS suppliers have the specialized assembly capabilities to integrate these.

Product Configuration

EMS providers can configure product SKUs and variations by flashing firmware and setting up software configurations. This allows them to customize product configurations in the factory.

Functional Testing

Whereas PCBA focuses on board level testing, an EMS will develop and conduct full functional testing of the completed product to ensure it operates as intended.

Regional Fulfillment

Global EMS providers can offer regional manufacturing and fulfillment from facilities located around the world to optimize shipping costs and transit times to end customers.

In summary, while turnkey PCBA focuses solely on assembling the bare board, EMS provides a more comprehensive set of product assembly, configuration, testing and fulfillment services. The table below summarizes the key differences:

Service	Turnkey PCBA	EMS
PCB Fabrication	✓	✓
PCB Assembly	✓	✓
Component Sourcing	✓	✓
Box Builds		✓
Electromechanical Assembly		✓
Product Configuration		✓
Functional Testing		✓
Regional Fulfillment		✓

Future Trends in Turnkey PCBA and EMS

The PCBA and EMS industries continue to evolve to keep pace with new technologies and shifting supply chain dynamics. Some key trends shaping the future of turnkey PCBA include:

Reshoring and Regionalization

The COVID-19 pandemic and trade tensions exposed risks in globally dispersed electronics supply chains. In response, many OEMs are looking to reshore PCBA to domestic providers or regionalize production to locations nearer to end markets.

Automation

To combat rising labor costs and labor shortages, turnkey PCBA vendors are investing heavily in robotics and factory automation. Greater automation enables PCBA vendors to cost effectively keep electronics manufacturing in higher cost regions.

Agile Manufacturing

Shortening product lifecycles are forcing PCBA providers to become more agile and able to quickly ramp production up or down in response to demand. More modular and software-defined manufacturing approaches support this need for greater agility.

Supply Chain Resiliency

Turnkey providers are focusing on making their electronics supply chains more resilient to disruption by expanding their supplier networks, sourcing more components domestically, and holding more buffer inventories of long lead-time parts.

Digital Transformation

PCBA vendors are embracing digital transformation by more tightly integrating their processes into client PLM and ERP systems; deploying smart factory technologies, and using data analytics and AI to optimize production.

By staying in front of these trends, turnkey PCBA and EMS partners can continue delivering greater value to OEM clients.

Conclusion

In this article, we’ve covered what you need to know about turnkey PCB assembly and EMS services. The key takeaways are:

• Turnkey PCBA simplifies PCB manufacturing by providing an end-to-end service from design to final assembly from one vendor.

• Using a turnkey provider offers benefits of simplified logistics, faster turnaround, cost savings, accountability and optimized manufacturability.

• The turnkey process spans design review, prototyping, parts procurement, PCB fabrication, assembly, testing, and final packaging.

• When selecting a turnkey partner consider their technical capabilities, testing and quality metrics, supply chain robustness, communication, and overall profile and reputation.

• EMS goes beyond bare board assembly to also include box builds, electro-mechanical assembly, product configuration, functional testing and regional fulfillment.

• The future of turnkey PCBA and EMS will be shaped by key trends of reshoring, automation, supply chain resiliency, agile manufacturing, and digital transformation.

By understanding the benefits and process of turnkey PCBA and partnering with the right provider, you can optimize the manufacturability, cost, quality, and speed of your PCB builds.

Frequently Asked Questions (FAQ)

What’s the difference between PCB assembly (PCBA) and PCB fabrication?

PCB fabrication is the process of manufacturing the bare printed circuit board, while PCBA is the process of soldering and assembling components onto the fabricated PCB. PCB fabrication creates the blank PCB, while PCBA adds components to it.

What are SMT and THT in PCB assembly?

SMT (surface mount technology) and THT (through hole technology) are the two main methods of assembling components onto a PCB. With SMT, components are soldered onto pads on the surface of the PCB. With THT, component leads are inserted into holes drilled through the PCB and soldered. SMT is more common for smaller, denser PCBs, while THT is often used for larger components and connectors.

How long does turnkey PCB assembly take?

Turnkey PCB assembly times vary based on PCB complexity, BOM size, and testing requirements. Simple PCBs can be turned in as few as 2-3 days while complex multilayer boards may take several weeks. On average most turnkey PCBA takes 1-3 weeks.

What are IPC classes in PCB manufacturing?

IPC classes refer to the IPC-A-610 standards that define quality acceptance criteria for PCB assembly. There are three classes: Class 1 for general electronics, Class 2 for dedicated service electronics, and Class 3 for high-reliability electronics. Higher classes have more stringent quality criteria. Selecting the right IPC class helps ensure the PCBA meets your product’s reliability needs.

What certifications should a turnkey PCBA vendor have?

Key certifications to look for in a turnkey vendor include:

• ISO 9001 for general quality management
• ISO 13485 for medical devices
• IATF 16949 for automotive
• IPC-A-610 for PCB acceptability
• J-STD-001 for soldered electrical and electronic assemblies

These certifications, while not mandatory, provide assurance the PCBA vendor adheres to industry standards and best practices.