A 4-layer multilayer printed circuit board consists of two outer copper layers and two internal layers-typically designated as continuous power and ground planes-bonded together by prepreg under high temperature and vacuum pressure. This architecture increases routing density, reduces electromagnetic interference (EMI), and maintains signal integrity for compact electronic hardware.

Supplied as bare boards for surface-mount (SMT) or through-hole (THT) assembly.
Validated through 100% automated electrical netlist testing prior to vacuum packaging.

Technical Specifications

Note: Standard production capabilities. Custom configurations require engineering review.

Parameter	Specification Range	Standard Tolerance
Layer Count	4 Layers	N/A
Finished Board Thickness	0.4mm – 3.2mm	+/-10%
Base Material (Laminate)	FR-4 (Tg 130C, 150C, 170C), High-Tg FR-4, Aluminum-backed (hybrid)	IPC-4101 compliant
Copper Weight	Outer: 1 oz (35um) to 3 oz (105um) Inner: 0.5 oz (18um) to 2 oz (70um)	IPC-A-600 Class 2 / Class 3
Min. Trace Width / Spacing	3.5 mil / 3.5 mil (0.09mm)	+/-20%
Min. Finished Hole Size	0.15mm (Mechanical), 0.10mm (Laser via capability)	+/-0.025mm
Surface Finish	ENIG, HASL (Lead-free), OSP, Immersion Silver, Immersion Tin	IPC-PL-011
Solder Mask Color	Green, Black, Matte Black, Blue, Red, White, Yellow	Visual inspection per IPC
Impedance Control Tolerance	+/-10% (TDR tested)	Engineering simulation required

Key Features

Internal Power/Ground Planes

Lowers ground impedance and stabilizes DC power distribution to sensitive ICs.

Controlled Electromagnetic Interference (EMI)

Dedicated internal planes shield high-frequency signals and reduce loop areas.

High-Density Routing

Accommodates fine-pitch BGAs and complex surface-mount components without increasing board footprint.

Thermal Management

Distributes heat evenly across internal copper planes, preventing localized thermal stress.

Applications

Industrial Automation

PLC controllers, motor drives, and industrial human-machine interfaces (HMIs).

Automotive Electronics

Infotainment sub-modules, LED lighting controllers, and sensor interfaces (non-safety-critical).

IoT & Telecommunications

Wi-Fi/cellular routers, gateway controllers, and edge computing nodes.

Medical Equipment

Patient monitors, diagnostic benchtop units, and laboratory testing devices.

Customization

Engineering support is available for custom stack-up design, impedance modeling, and material selection.

Stack-up Optimization: Customized dielectric thickness between layers to achieve target differential/single-ended impedance (50 ohm, 100 ohm).

Special Processes: Blind/buried vias, peelable solder mask, carbon ink jumpers, and edge plating.

Panelization: Customized array layouts (V-score or tab-route) optimized for pick-and-place assembly machines.

Quality Control & Laboratory Verification

Manufacturing follows IPC-A-600 standards. Every production panel undergoes multi-stage inspection:

AOI (Automated Optical Inspection): Detects open circuits, short circuits, etching defects, and copper residue on inner and outer layers prior to lamination.

X-Ray Registration Inspection: Verifies core-to-core alignment and drill registration accuracy prior to outer layer imaging.

100% Electrical Netlist Testing: Executed via Flying Probe Testers (for prototypes/NPI) or Bed-of-Nails fixtures (for volume production).

In-House Laboratory Analysis: Coupon testing for microsection analysis (verifying copper wall thickness and barrel integrity) and solderability testing per J-STD-003.

Manufacturing & Facility Capabilities

Production Floor Equipment: Equipped with direct imaging (DI) exposure systems, high-speed CNC drilling centers, multi-opening vacuum lamination presses, and horizontal electroplating lines ensuring uniform copper deposition.

Traceability: Lot-level material tracking utilizing laser-etched matrix codes on panel borders.

Certifications: ISO 9001:2015, IATF 16949 (Automotive Quality Management), ISO 14001, and UL-listed (E-number available upon request). Fully RoHS and REACH compliant.

Packaging & Delivery

Packaging: Vacuum-sealed anti-static ESD bags with desiccants and shock-absorbent bubble wrap. Heavy-duty double-wall corrugated cartons reinforced for international export freight.

Logistics Support: Express air freight for urgent prototypes (3 to 5 days transit) and sea/air freight consolidation for scheduled volume shipments.

FAQ

Q: What file formats are required to initiate production?

A: Gerber RS-274X file format along with an IPC-D-356 netlist and a fabrication drawing specifying board thickness, copper weight, and surface finish.

Q: How do you handle impedance-controlled 4-layer designs?

A: Submit your target impedance values and stack-up requirements. Our engineering team simulates trace width and dielectric spacing using Polar software before production release.

Q: What is the standard turnaround time for 4-layer prototypes?

A: Standard prototype fabrication takes 3 to 5 business days, subject to material availability and design complexity.

Q: Do you perform 100% electrical testing before shipment?

A: Yes, every single bare board is electrically tested against the original netlist file prior to vacuum packaging.