Introduction

Fast-turnaround is often needed for rigid-flex PCB prototypes and new product introductions to accelerate time-to-market. However, rigid-flex manufacturing typically has longer lead times due to process complexity.

This article examines strategies for obtaining quick-turn rigid-flex boards, covering:

• Lead time challenges for rigid-flex PCBs
• Planning approaches to enable fast turnaround
• Manufacturing optimizations for cycle time reduction
• Testing considerations for rapid builds
• Cost impacts of expedited fabrication
• When to use quick-turn vs standard lead times

Understanding techniques to get fast rigid-flex PCB deliveries helps manage new product prototyping, engineering validation builds, and low volume ramps efficiently.

Lead Time Challenges for Rigid Flex PCBs

Standard lead times for rigid-flex PCB fabrication range from 3-4 weeks for simple 2-4 layer boards, up to 12-16 weeks for complex multilayer designs. There are several factors driving these lead times:

Multistage Processes

• Numerous fabrication steps – layer processing, lamination, drilling, imaging, plating, patterning, etc.

Engineering Work

• Extensive CAM/CAD preparations due to board complexity
• Electrical, mechanical, and thermal analysis

Fabrication Precision

• Tight tolerances for layer alignments and interconnects
• High level of process controls needed

Testing and Inspection

• Rigorous quality validation steps add time
• ICT, flying probe, x-ray, AOI, etc.

Logistics

• Movement of work-in-process (WIP) between process areas
• Supplier lead times for long-lead materials

Planning Strategies for Fast Turn Rigid Flex PCBs

Several planning techniques can support quick-turn rigid-flex PCB fabrication:

Design for Manufacturability (DFM)

• Simplify layer count, density, and board size where possible
• Avoid unnecessarily tight tolerances
• Allow adequate spacing for manufacturing capabilities

Pre-production Engineering

• Complete design, analysis, CAD, and CAM work upfront before build initiation
• Resolve DFM issues through engineering collaboration
• Qualify processes and materials in advance

Forecasting and Ordering

• Provide forecasts for prototype and pre-production demand
• Order long lead-time materials like flex substrates early

Open Communication

• Align with manufacturer on expectations upfront
• Emphasize priority of fast turnaround time
• Quick issue resolution prevents delays

Manufacturing Optimizations for Quick Turn Rigid Flex

Manufacturers use various techniques to achieve expedited rigid-flex PCB fabrication:

Front-Loading Work

• Complete as much engineering and CAM prep as possible before production
• Have materials, tooling, and fixtures ready ahead of start

Prioritizing Schedules

• Schedule production capacity in advance
• Give preference to quick-turn job over standard orders
• Resource planning focused on fast turn WIP

Process Streamlining

• Reduce/eliminate non-critical operations if low risk
• Standardize processes where possible
• Stage materials at process steps

Direct Material Sourcing

• Maintain stock of long lead-time materials like flex circuits
• Suppliers allocated for quick-turn material supply
• Local material sourcing minimizes delays

Multi-Step Processing

• Parallel steps for drilling, imaging, plating, etc.
• Continuous workflows with minimized queues

Automated Handling

• Automated material transport between processes
• Automated inspection techniques
• Reduce human-related delays

Testing Considerations for Fast Turn Rigid Flex

Testing is key for quality but can extend lead times. Some ways to address this for quick-turns:

• Prioritize essential tests – Defer non-critical testing if acceptable risk
• Early test development – Start programming and fixturing in parallel to build
• Modular fixturing – Standard interface plates speed fixturing changes
• Known-good materials – Reduce incoming component inspection
• Accelerated workflows – Straight-through material flows minimize WIP queues
• Temporary testing – Use probing or flying probe test if fixture unavailable
• Dedicated resources – Allocate staff specifically for quick-turn testing

Cost Impacts of Expedited Rigid Flex Fabrication

Fast-turn rigid-flex PCBs often incur cost premiums for expedited delivery:

• Materials rush charges – Upcharges for quick material supply
• Opportunity cost – Revenue loss from displaced standard orders
• Overtime labor – Weekend and extended shifts to achieve lead time
• Expedited shipping – Faster freight and logistics costs
• Low volume pricing – Loss of high volume discounts
• Testing complexity – More difficult test programming
• Prioritization resources – Dedicated program management

However, this is often offset by the value of getting to market faster and realizing revenue sooner.

When Quick-Turn Rigid Flex is Recommended

Here are typical scenarios where fast-turnaround rigid-flex PCB production is advisable:

• New product prototyping – Accelerating development cycles
• Design validation builds – Iterating to prove the design quickly
• Customer sampling – Providing samples to aid customer testing
• Clinical evaluations – Faster delivery of boards for trials
• Pilot test runs – Validating manufacturability before ramp
• Time-sensitive programs – Missile defense, medical devices, etc.
• Supply chain gaps – Obtaining boards rapidly to prevent line downs

Standard lead times are recommended once the product progresses to volume production phase.

Conclusion

Rigid-flex PCBs inherently have longer fabrication lead times than simple rigid boards, but techniques exist to reduce turnaround time through planning, optimization, resource allocation, and managing cost tradeoffs.

Communicating program priorities to manufacturing partners early and leveraging expedited services when entering new product introduction can substantially accelerate time-to-market.

Understanding the timeline, costs, and tradeoffs for obtaining fast turn prototypes enables engineering teams to balance speed with budget and make smart sourcing decisions.

Frequently Asked Questions

Q: What is the typical lead time for a complex 10 layer rigid-flex PCB?

A: For a 10 layer rigid-flex design, standard lead times range from 8-14 weeks depending on complexity. Quick-turn can be 5-6 weeks.

Q: What are some key considerations for designing rigid-flex PCBs for fast fabrication?

A: Simplify layer count and densities where possible, allow adequate spacing, standardize materials and processes, eliminate non-critical operations.

Q: How can testing time be reduced for quick-turn rigid-flex boards?

A: Prioritize critical tests only, pre-plan fixture design, use temporary probing methods, allocate dedicated test resources, accept a bit more risk.

Q: What are the main premium costs associated with fast turnaround rigid-flex?

A: Main premium costs are material expediting, overtime labor, opportunity cost vs standard orders, freight acceleration, and potential yield losses.

Q: What lead time can be expected for a simple 2-4 layer rigid-flex PCB?

A: A simple design can often be delivered in 1-2 weeks. Under ideal conditions, some manufacturers can provide in less than 1 week.