PCB Fabrication

4-layer HDI first-level FLEX PCB

Well Circuits specializes in the fabrication of high-performance flexible printed circuit boards (FPC). Our 4-layer HDI first-level FLEX PCB is engineered for complex, space-constrained applications requiring superior signal integrity and dynamic flexibility. Manufactured in our ISO 9001-certified facility, this FPC solution integrates High-Density Interconnect (HDI) technology with a robust 4-layer flexible construction, offering designers an advanced platform for miniaturization and enhanced functionality. It is ideal for critical consumer, automotive, medical, and industrial devices where reliability and compact design are paramount. All production adheres strictly to IPC standards, with options for IPC Class 2 or Class 3 builds.

Key Specifications

Specification	Details	Notes
Board Type	4-Layer HDI First-Level Flex PCB	Combines flexibility with high component density.
Base Material	Polyimide (PI) Film	Standard thickness options: 1 mil, 2 mil. Adhesive-less PI available for superior flexibility and thermal performance.
Copper Thickness	Outer Layers: 0.5 oz to 1 oz (18 µm to 35 µm) Inner Layers: 0.5 oz to 1 oz (18 µm to 35 µm)	Custom copper weights available upon request.
Minimum Line Width/Spacing	2 mil / 2 mil (0.05 mm / 0.05 mm)	Achievable with advanced manufacturing processes for HDI designs.
Minimum Mechanical Drill Size	6 mil (0.15 mm)	For conventional through-holes and component mounting.
Minimum Microvia Drill Size	3 mil (0.075 mm)	For first-level HDI connections, enhancing routing density.
Microvia Aspect Ratio	0.8:1 to 1:1	Ensures reliable plating for high-density interconnections.
Dielectric Thickness (Flex)	0.5 mil to 2 mil (0.0127 mm to 0.0508 mm)	Controlled for impedance and flexibility.
Surface Finish Options	ENIG (Electroless Nickel Immersion Gold) OSP (Organic Solderability Preservative) Immersion Silver Immersion Tin EPIG (Electroless Palladium Immersion Gold)	Selected based on application, solderability, and environmental requirements.
Solder Mask / Coverlay	Polyimide (PI) Coverlay Flexible Solder Mask (LPI)	Offers mechanical and electrical protection. Coverlay provides superior flexibility.
Stiffener Options	Polyimide (PI), FR-4, Stainless Steel	Used for component support, selective rigidity, or ZIF connector reinforcement.
Impedance Control Tolerance	± 10% (± 5% available for critical designs)	Ensures signal integrity for high-speed applications.
Outline Tolerance	± 3 mil (± 0.076 mm)	Achieved via precision laser cutting or routing.
Operating Temperature	-40°C to +125°C (material dependent)	Suitable for a wide range of environmental conditions.
IPC Compliance	IPC-6012 Class 2 (Standard) IPC-6012 Class 3 (High Reliability)	All builds meet general requirements for rigid-flex and flexible PCBs. Specify desired class at order.
Quality Assurance	100% AOI (Automated Optical Inspection) 100% Electrical Test (Flying Probe or Fixture)	Ensures defect-free manufacturing and electrical continuity.

Applications

The compact and resilient design of our 4-layer HDI first-level Flex PCBs makes them indispensable for next-generation electronics across various sectors:

Advanced Consumer Electronics: Essential for miniaturized devices such as smartphones, tablets, smartwatches, wearables, and high-resolution cameras, enabling complex functionality in sleek form factors.
Automotive Systems: Critical for ADAS modules, infotainment systems, sensor arrays, lighting systems, and battery management systems, where space is limited and reliability in harsh environments is crucial.
Medical Devices: Used in implantable devices, diagnostic equipment, patient monitoring systems, and surgical tools that require flexibility, bio-compatibility, and high signal integrity.
Aerospace & Defense: Deployed in avionics, portable communication devices, missile guidance systems, and satellite components, demanding extreme reliability and performance under challenging conditions.
Industrial IoT & Robotics: Ideal for compact sensors, actuators, drone technology, and robotic arms, facilitating complex interconnections in dynamic and space-constrained environments.
High-Reliability Computing: Supports compact servers, data storage units, and high-performance computing modules where board space is at a premium and data integrity is paramount.

Why Choose WellCircuits?

Certified Quality & Reliability: Our manufacturing processes are rigorously managed under an ISO 9001-certified quality system, ensuring consistent excellence. We adhere to stringent IPC standards, including IPC-6012 for rigid-flex and flexible PCB fabrication, IPC-A-610 for acceptability of electronic assemblies, and IPC-2221 for generic design standards. We offer builds to IPC Class 2 (dedicated service electronic products) and IPC Class 3 (high-reliability electronic products) based on your application's demands.
Advanced Manufacturing Capabilities: Well Circuits operates a state-of-the-art facility equipped with precision machinery for HDI drilling, fine line etching, and flexible material handling. Our expertise in first-level HDI technology allows for superior routing density and reduced board size, pushing the boundaries of miniaturization.
Comprehensive Quality Control: Every 4-layer HDI flex PCB undergoes a battery of tests, including 100% Automated Optical Inspection (AOI) for visual defects and 100% electrical testing to verify circuit continuity and isolation. We also perform X-ray inspection for microvia integrity and offer impedance testing for controlled impedance designs, ensuring your boards perform as expected.
Expert Design for Manufacturability (DFM) Support: Our team of experienced PCB engineers provides comprehensive DFM reviews for every project. We work closely with you from concept to production, identifying potential manufacturing challenges early and optimizing your design for cost-effectiveness, reliability, and faster turnaround times.

Pricing & Lead Time

Well Circuits offers competitive pricing for our 4-layer HDI first-level Flex PCBs, tailored to your specific design requirements and order volume. Our standard lead times for sample production typically range from 3-5 working days, with mass production orders generally fulfilled within 5-15 working days, depending on complexity and quantity. For precise quotations and detailed lead time estimates, we invite you to submit your Gerber files and specifications.

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