Flexible PCB Assembly

HCJMPCBA’s Precision Solutions for Advanced Electronics

Introduction: What is Flex PCB Assembly?

Flexible PCB assembly (or flex pcba) is the process of integrating electronic components onto flexible printed circuits (FPCs) to create functional, bendable electronic modules. Unlike rigid PCB assembly, this technology leverages the unique properties of flexible circuit boards—made from polyimide (PI) or PET materials—to enable compact, lightweight designs that adapt to irregular spaces .

At HCJMPCBA, we specialize in flex circuit assembly for industries ranging from consumer electronics to aerospace. As a leading flexible pcb manufacturer and supplier, our end-to-end services cover prototype development, small-batch production, and mass flex pcb production, ensuring precision and reliability at every stage.

Differences Between Flex PCB Assembly and Rigid Assembly

The unique properties of flexible pcb boards demand specialized assembly processes distinct from rigid PCB manufacturing. Below is a detailed comparison:

Aspect	Flex PCB Assembly	Rigid PCB Assembly
Base Material	Polyimide (PI), PET (flexible substrates)	FR4, CEM (rigid substrates)
Assembly Fixtures	Custom rigid carriers to prevent bending during soldering	Standard vacuum fixtures
Component Limitations	No heavy components on bend zones; requires stiffeners for large parts	No restrictions on component weight/location
Soldering Temperature	Lower peak temps (≤245°C) to protect flexible substrates	Higher peak temps (260°C+) for FR4 durability
Inspection Methods	3D AOI + manual bend testing	2D AOI + X-ray (for BGAs)
Key Application	Wearables, foldable phones, automotive sensors	Computers, industrial controllers
Connector Requirements	Specialized flex pcb connectors (e.g., board-to-board flex connectors)	Standard pin headers, USB connectors

Design Considerations for Flex PCB Assembly

Successful flexible pcb assembly starts with optimized design. Below are critical guidelines to ensure manufacturability and performance:

Design Aspect	Best Practices	Common Pitfalls to Avoid
Bend Zone Design	– Maintain bend radius ≥5x board thickness (single-layer) – ≥20x for multilayer flex pcbs – Use curved traces instead of right angles	– Placing components on bend lines – Sharp 90° traces in flex areas
Component Placement	– Keep components ≥3mm from bend zones – Use SMDs (01005–1210 size) for compactness – Add stiffeners under BGAs/QFNs	– Through-hole components on flexible sections – Uneven component distribution (causes warping)
Material Selection	– Polyimide pcb for high temp (≥250°C) – PET for low-cost consumer goods – 1oz copper for balance of flexibility/conductivity	– Using FR4 in flex zones – Thin copper (≤0.5oz) for high-current paths
Connector Integration	– Specify flex connector pcb with locking mechanisms – Leave ≥2mm clearance around connector pads	– Standard rigid connectors on flex sections – Insufficient pad size for flex connectors
Solder Mask & Coverlay	– Coverlay opening ≥0.6mm × 0.6mm – Solder mask bridge ≥0.1mm (green) – Align coverlay with bend axes	– Coverlay overlapping solder pads – No coverlay on high-stress bend zones
Impedance Control	– Single-ended: 50Ω ±10% – Differential pairs: 100Ω ±10% – Use PI substrate for stable impedance	– Ignoring impedance in high-speed flexible printed circuits – Inconsistent trace width in controlled-impedance paths

Characteristics of Flex Board Assembly

HCJMPCBA’s flexible pcb assembly delivers unique attributes that set it apart in the industry:

Characteristic	Detailed Description	Industry Impact
High Precision	Supports component placement down to 01005 size; trace/spacing ≥2mil ; positional accuracy ±0.01mm	Enables miniaturization of bendable circuit boards for wearables
Material Compatibility	Works with PI, PET, and polyimide flex pcb; compatible with all surface finishes (ENIG, OSP, immersion tin)	Flexibility to meet diverse application requirements (automotive/medical)
Environmental Resilience	Assemblies withstand -40°C to +125°C; resistant to moisture, vibration, and chemicals	Reliable performance in harsh industrial/aerospace environments
Hybrid Assembly Capability	Integrates rigid flex pcbs with both SMT and THT components; supports stiffener lamination (PI/FR4/aluminum)	Reduces assembly steps for complex devices (e.g., smartwatches)
Cost Efficiency	Eliminates wiring harnesses; reduces connector count; scalable for high-volume flex pcb fab	Lowers total cost of ownership for consumer electronics brands
Fast Prototyping	Turnaround time for pcb prototype assembly: 3–5 business days	Accelerates product development cycles for tech startups

HCJMPCBA’s Flex PCB Assembly Features & Capabilities

Our state-of-the-art facility delivers industry-leading flexible pcb assembly services. Below is a comprehensive overview of our technical capabilities:

Category	Capability	Technical Specifications
Board Types	Flexible PCB	1–8 layers; PI/PET substrate; thickness 0.08–0.4mm
	Rigid-Flex PCB	2–16 layers; PI + FR4; bend radius ≥10x thickness
	Flexible HDI PCB	Microvias (4mil); trace/spacing 2mil/2mil
Component Handling	SMT Components	01005 to 50mm BGA; QFN, LGA, SOT, SOIC
Component Handling	Special Components	Flex pcb connectors, LEDs, sensors, batteries
Manufacturing Parameters	Board Size	Min: 6×6mm; Max: 800×240mm (2-layer)
	Copper Thickness	0.5oz–2oz (17.5μm–70μm)
	Surface Finish	ENIG, OSP, immersion tin, chemical silver
Production Capacity	Order Volume	1 piece (prototype) – 1,000,000+ pieces
Production Capacity	Lead Time	3–5 days (prototype); 7–14 days (mass production)
Quality & Compliance	Standards	IPC-A-610, ISO 9001, RoHS, REACH
Quality & Compliance	Testing Certifications	AEC-Q200 (automotive), IEC 60601 (medical)
Value-Added Services	Engineering Support	DFM analysis, flexible pcb design optimization, component sourcing

HCJMPCBA Flexible Printed Circuit Board Assembly [Step by Step]

Step 1: Design Review & DFM Analysis

Receive Gerber files, BOM, and pick-and-place data from clients.

Our engineers conduct Design for Manufacturability (DFM) checks to verify:

Bend zone compliance (radius, trace routing).

Component compatibility with flexible substrates.

Flex pcb connector pad dimensions.

Issue a DFM report with recommendations within 24 hours.

Step 2: Material Preparation & Kitting

Source certified materials:

Substrates: PI (Kapton) or PET flexible pcb material .

Components: From authorized distributors (Digi-Key, Mouser) to ensure authenticity.

Consumables: Low-temperature solder paste (Sn-Ag-Cu, melting point 217°C).

Kit components by value stream and verify quantities against BOM.

Step 3: Pre-Assembly Preparation

Cut flexible pcb boards to panel size using laser cutting (tolerance ±0.1mm) .

Apply rigid carriers to flex panels to prevent deformation during assembly.

Clean boards with ultrasonic baths to remove oil/residues .

Step 4: Solder Paste Application

Use stainless steel stencils (thickness 0.12–0.15mm) for precise paste deposition.

Print solder paste onto pads with a DEK printer (accuracy ±0.02mm).

Inspect paste volume and alignment with 3D SPI (Solder Paste Inspection).

Step 5: Component Placement

Deploy Yamaha YSM20R pick-and-place machines for high-speed SMT placement:

Speed: 50,000 components per hour.

Accuracy: ±0.01mm for chips; ±0.02mm for BGAs.

Manually place odd-form components (e.g., flex connector pcb).

Step 6: Reflow Soldering

Use nitrogen reflow ovens with 8 heating zones to protect flexible substrates:

Peak temperature: 235–245°C (profile optimized for PI).

Cooling rate: ≤3°C/sec to avoid thermal stress.

Nitrogen atmosphere (99.9% purity) reduces oxidation for reliable joints.

Step 7: Post-Assembly Inspection & Testing

Test Type	Equipment Used	Acceptance Criteria
Visual Inspection	Online AOI	No missing components, solder bridges, or tombstoning
Electrical Testing	Flying Probe Tester	100% continuity; no opens/shorts
Bend Testing	Manual + Automated Bend Tester	10,000 cycles at minimum bend radius (no trace cracking)
X-Ray Inspection	Yxlon Cheetah	BGA solder ball voiding <20%

Step 8: Final Processing & Packaging

Remove rigid carriers and trim panels to individual units.

Apply conformal coating (optional) for moisture/chemical resistance.

Package in anti-static bags with desiccants; label with part numbers/lot codes.

Why Choose HCJMPCBA as Your Flex PCB Assembly Partner?

As a trusted flexible pcb manufacturer and supplier, HCJMPCBA combines technical expertise with customer-centric service:

Precision: Our SMT lines achieve 0.01mm placement accuracy for flexible printed circuit boards.

Speed: 3-day prototype turnaround to accelerate your product launch.

Quality: 99.98% first-pass yield backed by IPC standards.

Flexibility: Support for flex pcbs, rigid flex pcbs, and custom flex connector pcb integration.

Whether you’re developing a foldable smartphone, automotive sensor, or medical device, our flexible pcb assembly services deliver the reliability and performance your project demands.

Frequently Asked Questions (FAQs) About Flex PCB Assembly

1. What is the minimum order quantity (MOQ) for flex PCB assembly?

We have no strict MOQ—we support 1-piece pcb prototype assembly for R&D and 100,000+ units for mass production.

2. Can you handle rigid flex pcb assembly?

Yes. We specialize in hybrid assembly for rigid flex pcbs, integrating rigid FR4 sections with flexible PI layers and components on both.

3. What file formats do you accept for flexible pcb design?

We accept Gerber (RS-274X), ODB++, BOM (Excel/CSV), pick-and-place (CSV/TXT), and CAD files (Altium, KiCad, Eagle).

4. How do you ensure quality in flex pcb assembly?

Our quality control includes:

IPC-A-610 Class 2/3 compliance.

100% electrical testing and AOI inspection.

In-process checks at 5 critical stages (paste, placement, reflow, test, packaging).

5. What is the lead time for flexible pcb assembly?

Prototypes: 3–5 business days.

Small batches (10–100 units): 7–10 days.

Mass production: 10–14 days (plus 2–3 days for component sourcing if needed).

6. Do you supply flex pcb connectors and other components?

Yes. Our component sourcing team procures flex pcb connectors, passives, ICs, and custom parts from authorized distributors. We also offer obsolete component replacement.

7. Can you assemble polyimide flex pcb for high-temperature applications?

Absolutely. We use high-temperature solder paste (260°C peak) and ENIG surface finish for polyimide flex pcb used in automotive/aerospace environments.

8. What is the cost of flex circuit assembly?

Cost depends on:

Number of layers (1-layer:
$0.5-$

1/unit; 4-layer:
$2-$

5/unit for small batches).

Component count (more BGAs/connectors increase cost).

Volume (10,000+ units reduce per-unit cost by 30–40%).

9. Do you offer flexible pcb assembly for medical devices?

Yes. We are ISO 13485 certified and assemble flexible printed circuits for pacemakers, ECG machines, and wearable health monitors.

10. What is the difference between flex pcb assembly and flex circuit assembly?

They are interchangeable terms referring to the process of mounting components on flexible circuit boards.

11. Do you offer design services for flexible pcb boards?

While we specialize in assembly, our engineers provide DFM reviews and can recommend design tweaks. For full design, we partner with leading flex circuit manufacturers.

12. Can you handle expedited flex pcb production?

Yes. We offer 48-hour turnaround for urgent pcb prototype assembly (additional 50% fee applies).