Posts Tagged ‘Multilayer Copper PCB’

What is copper multilayer PCB? Let’s discover its material, benefits, applications, design guide for wearable device, production process through this blog.

What is Copper Multilayer PCB?

Copper Multilayer PCB consist of alternating copper conductive layers and insulating materials (such as FR-4 or polyimide) bonded together through a lamination process. Copper’s high thermal conductivity (386W/m·K) and electrical conductivity support complex circuit designs, enabling high-density interconnection between layers through through-holes, blind vias, or buried vias.

This type of PCB is suitable for high-power applications (such as automotive electronics and 5G base stations), offering superior heat dissipation and signal stability compared to single- or double-layer PCBs. Its symmetrical structure (e.g., copper-prepreg-core-prepreg-copper) enhances mechanical strength and controls impedance. Some models also utilize thermal isolation technology to directly conduct heat.

What is Material of Multilayer Copper PCB?

1. Conductive Layer

• Composition: Electrolytic copper foil (ED) or rolled copper foil (RA)
• Features: Thickness 0.5–6 oz/ft² (17–210 μm), conductivity ≥58 MS/m (20°C), surface finish available: brown oxide (OSP) or nickel-gold (ENIG).

2. Insulation

• FR-4: Epoxy resin + fiberglass, dielectric constant 4.2–4.8 (1 GHz), heat resistance 130°C (standard) / 170°C (high Tg).
• Polyimide (PI): Dielectric constant 3.4–3.6 (1 GHz), heat resistance >250°C, short-term temperature resistance ≥300°C.

3. Prepreg (PP)

• Composition: 7628/2116/1080 glass cloth impregnated with epoxy resin
• Features: Thickness 0.05–0.2mm (0.1–0.4mm after lamination), resin content 52%–65%, curing conditions 180°C/60min.

4. Metal Substrate (Optional)

• Aluminum Substrate: 1050/6061 alloy, thermal conductivity 180–220 W/m·K, thickness 1.0–3.2mm.
• Copper Substrate: Electrolytic copper, thermal conductivity 386 W/m·K, thickness 0.5–2.0mm.

5. High-Frequency Material (Optional)

• PTFE: Polytetrafluoroethylene, dielectric constant 2.2–2.5 (10 GHz), dissipation factor <0.001 (10 GHz).
• Rogers RO4003C: dielectric constant 3.38 (10 GHz), dissipation factor 0.0027 (10 GHz).

6. Solder Mask

• Composition: Liquid Photosensitive Solder Mask Ink (LPI)
• Characteristics: Thickness 10–25μm, Temperature Resistance ≥ 150°C (short-term), Insulation Resistance ≥ 1×10⁸Ω.

What Are Advantages of Copper Multilayer PCBs?

Benefits of copper multilayer PCB:

• High-density integration capabilities: By stacking multiple conductive layers (up to 32 layers), complex circuits can be integrated within a limited space, meeting the demands of miniaturized devices such as smartphone motherboards.
• Excellent heat dissipation performance: Copper foil has a thermal conductivity of 400. W/m·K (nearly twice that of aluminum substrates), combined with a thick copper design (3–10 oz), allows for rapid heat conduction and reduces the junction temperature of high-power devices.
• High-frequency signal integrity: Specialized high-frequency materials (such as PTFE) have a dielectric constant as low as 2.2–3.5, reducing signal loss and making them suitable for 5G base stations and radar systems.
• Optimized electromagnetic compatibility: Multi-layer ground and power planes effectively shield electromagnetic interference (EMI) and reduce crosstalk risks.
• Improved mechanical strength: Copper substrates offer superior deformation resistance to traditional FR-4, making them suitable for vibration environments such as automotive electronics.
• Current carrying capacity: Thick copper layers (6 oz+) support high current transmission and reduce voltage drop in power modules.
• Design flexibility: Supports advanced processes such as blind and buried vias and mixed dielectric layers to meet the needs of high-frequency, high-speed, and high-power hybrid designs.
• Long-term reliability: Copper’s oxidation resistance and multi-layer laminate structure (using prepreg PP) extend product life, making them suitable for industrial control equipment.

What Are Applications of Copper Multilayer PCB?

• Communications Equipment: 5G base stations, routers, mobile phone signal repeaters, fiber optic receivers
• Computers and Data Centers: Server motherboards, hard drive controllers, graphics cards, storage devices
• Medical Equipment: Heart monitors, CT scanners, X-ray equipment
• Industrial Control and Automotive Electronics: Motor controllers, industrial automation systems, power converters, in-vehicle electronics
• Aerospace: Satellite systems, space exploration equipment, radar
• Consumer Electronics: Smartphones, wearable devices, game consoles
• Energy and Power Systems: Power amplifiers, battery chargers, rectifiers, high-power conversion devices

How to Design a Copper Multilayer PCB for Wearable Device?

1. Material Selection & Substrate Optimization

• Substrate: Prioritize polyimide (PI) or liquid crystal polymer (LCP), thickness 0.05–0.1mm, for flexibility (bending radius <5mm) and high-temperature resistance (Tg >250℃).
• Conductive Layer: Use ultra-thin rolled annealed copper foil (RA, 0.5oz/17μm) to balance flexibility and conductivity (conductivity ≥58 MS/m).
• Adhesive Layer: Apply low-modulus prepreg (PP) to reduce interlayer stress and prevent cracking during bending.

2. Stackup Design & Flexibility

• Layer Count: Prioritize for 4-layer boards (Signal-Ground-Power-Signal) with total thickness 0.4–0.6mm to minimize weight.
• Symmetry: Distribute copper layers symmetrically (e.g., Cu-PI-Cu) to avoid warping during bending; place ground and power planes adjacent to reduce EMI.
• Flexible Zones: Use coreless structures (copper foil + PI only) in bending areas (e.g., wristband connections) for unrestricted flexibility.

3. Signal Integrity Assurance

• High-Speed Signals: Design Bluetooth/Wi-Fi antennas as microstrip lines with 50Ω impedance control (trace width 0.15mm, spacing 0.1mm) and avoid 90° bends.
• Differential Pair Routing: Route high-speed interfaces (USB, MIPI) with equal length (tolerance ±5mil) and spacing ≥3x trace width to minimize crosstalk.
• Shielding: Add copper shielding layers (width ≥2mm) around antennas, grounded via stitching to reduce external EMI.

4. Power Distribution & Low-Power Design

• Layered Power: Implement split power planes (e.g., 1.8V/3.3V) with power-ground spacing 0.1mm and decoupling capacitors (10μF + 100nF).
• Low-Power Components: Select ultra-low-power MCUs (e.g., STM32L series) and PMICs, paired with hardware watchdogs to prevent lockups.
• Layout Optimization: Place batteries, PMICs, and MCUs close to minimize trace length and reduce static power consumption.

5. Thermal Management Strategies

• Heat Dissipation: Place copper foils (1oz thickness) under heat-generating components (MCUs, power chips) and connect via thermal vias (diameter 0.2mm, pitch 0.5mm) to external thermal areas.
• Thermal-Electric Separation: Isolate high-power LEDs or battery chargers with dedicated copper layers to prevent heat transfer to sensitive components.
• Material Enhancement: Embed graphene thermal films (0.01mm thickness) in critical zones to improve lateral heat conduction.

6. Mechanical Reliability & Bend Resistance

• Solder Mask: Use high-flexibility solder mask (e.g., Taiyo PSR-9000), thickness 10μm, rated for >100,000 bend cycles.
• Surface Finish: Apply ENIG (Electroless Nickel Immersion Gold) or OSP (Organic Solderability Preservative) to prevent copper oxidation and ensure solder reliability.
• Validation: Pass dynamic bend tests (radius 3mm, 1Hz frequency, 10,000 cycles) and accelerated aging (85℃/85%RH, 168 hours).

7. Electromagnetic Compatibility (EMC) & Compliance

• Grounding: Connect metal enclosures (e.g., wristband, buttons) to PCB ground via spring contacts or conductive adhesives, forming a Faraday cage to mitigate ESD.
• Certification: Achieve CE (EU) or FCC (US) EMC compliance, testing across 80MHz–6GHz to ensure stable operation in complex electromagnetic environments.
• Wireless Charging: Position Qi-standard coils at PCB edges, away from antennas and sensors to avoid interference.

How was Copper Multilayer PCB Made?

1. Substrate Preparation

• Select FR4 glass fiber epoxy resin laminate as substrate, with copper foil cladding (thickness 1oz/2oz).

2. Inner Layer Pattern Transfer:

• Apply photosensitive dry film, transfer circuit pattern via UV exposure, and dissolve unexposed areas.
• AOI (Automatic Optical Inspection) verifies line precision and marks defects.

3. Inner Layer Etching & Oxidation

• Chemically etch copper not protected by dry film to form inner layer circuits.
• Black oxide/brown oxide treatment on copper surfaces to enhance interlayer adhesion.

4. Lamination & Pre-Press

• Stack inner layer core boards, prepreg sheets, and outer layer copper foils alternately, aligning via positioning holes.
• High-temperature/high-pressure lamination (180-200℃) melts resin to fill gaps, forming a unified board.

5. Mechanical Drilling

• CNC drilling machine processes through-holes/blind holes with diameter accuracy ±0.05mm.
• Clean hole-wall resin residues (desmear).

6. Electroless Copper Plating

• Deposit electroless copper (0.3-0.8μm) on hole walls to establish conductive base.
• Electroplate to thicken copper layer (20-25μm) for reliable hole-wall conductivity.

7. Outer Layer Pattern Transfer

• Repeat inner layer pattern transfer process, addressing hole alignment.
• Use high-precision exposure equipment to compensate for interlayer deviation.

8. Outer Layer Etching & Stripping

• Secondary etching defines outer layer circuits, with tin layer protecting desired copper areas.
• Alkaline solution strips dry film, retaining circuit patterns.

9. Solder Mask & Silkscreen

• Apply liquid photosensitive solder mask (green/black), expose and develop to expose pads.
• Silkscreen component identifiers (white/yellow text).

10. Surface Finish

• Treat pad areas with ENIG (Electroless Nickel Immersion Gold)/immersion tin/OSP to prevent oxidation and enhance solderability.
• Plate gold finger areas with hard gold for wear resistance (e.g., board-edge connectors).

11. Electrical Testing

• Flying probe test or bed-of-nails test verifies continuity and insulation.
• AOI re-inspects for micro-shorts/opens.

12. Profiling & Packaging

• CNC milling cuts board outlines; V-score or punching for separation.
• Final cleaning, drying, and vacuum moisture-proof packaging.

Why Choose Best Technology as Copper Multilayer PCB Manufacturer?

Reasons why choose us as copper multilayer PCB manufacturer:

• 19 years of experience in copper substrate R&D: Precisely addressing interlayer heat dissipation and current carrying challenges in high-power multi-layer copper substrates, ensuring long-term stable operation of high-power devices (such as projectors/lasers).
• Triple international quality certification (ISO9001/IATF16949/ISO13485): Medical and automotive-grade copper substrate production standards ensure ±1μm copper thickness uniformity in multi-layer board holes and zero deviation in electrical performance.
• Customized thermal management solutions for copper substrates: Embedded copper pillars/thermoelectric separation structures reduce the thermal resistance of multi-layer boards to 0.5°C/W, extending the life of LEDs/power modules by over 30%.
• Cost-optimized copper substrate design: Utilizing a gradient copper foil thickness (1oz outer layer + 2oz inner layer) to balance conductivity and heat dissipation requirements, saving 15% in material costs compared to traditional designs.
• 24-hour copper substrate rapid prototyping service: Laser drilling and electroless copper plating processes deliver high-complexity (20+ layers) copper substrate prototypes within 48 hours, accelerating the validation cycle for high-power products.
• Free Copper Substrate Design for Material (DFM) Analysis: Preemptively identify design risks such as copper layer distribution and blind via alignment, preventing interlayer cracking caused by thermal expansion coefficient mismatch and reducing secondary re-board rework costs.
• 100% Automated Optical Inspection (AOI): Detects hole wall voids and copper nodules, a common feature of copper substrates, with a 0.01mm² level of defect detection, ensuring zero defective batch orders.
• Full-Process Copper Substrate Solution: From thermal simulation (Flotherm) to copper layer etching and surface treatment (ENIG/HASL), we provide a one-stop service, reducing the cost of coordinating multiple suppliers.
• Ultra-Thin Copper Substrate Process (0.2mm total thickness): Combining flexible PI substrate and copper foil calendering technology, we achieve a bend radius of less than 1mm for multi-layer copper substrates for wearable devices while maintaining a current density of 10A/cm².

Our Copper PCB Capabilities

Items	Technical Parameters
Product model	Copper PCB
Copper trace thickness	1OZ, 2OZ, 3OZ, 4OZ, up to 10OZ
Thermal Conductivity	1.0, 1.5, 2.0, 3.0W/m.K
Surface finishing	HAL(LF)/ Gold Immersion/ Gold plating/ OSP/ Immersion Tin/ Silver Immersion
Soldermask Color	White/Black/Green/Blue/Red/Yellow
Layers	1L, 2L, 4L, 6L, 8L, double sided, COB
Maximum dimension	1,100mm*480mm; 1,500x300mm
Minimum dimension	5mm*5mm
Minimum Line width/space	0.1mm/0.1mm
Warp and twist rate	≤0.75%(thickness:1.6mm, measurement:300mm×300mm)
Board Thickness	0.3－4.5mm
Die-Punching dimension tolerance	±0.15mm
V-cut positioning tolerance	±0.1mm
Manufacturing capability	6000m2
Wall Cu thickness	15-25um
Alignment tolerance	±0.076mm
Minimum diameter of die-punching hole	Thickness <=1.0mm:   1.0mm
	Thickness 1.2-3.0mm: 1.5mm
	Thickness 4.0mm: 2.0mm
Minimum size the square groove/slot/cutout	Thickness <=1.0mm:  0.8mm×0.8mm
	Thickness 1.2-3.0mm:  1.0×1.0mm
	Thickness 4.0mm:  1.5×1.5mm
Outline Tolerance	CNC routing：±0.1mm; Die-punching：±0.15mm
Minimum diameter of hole	0.3mm; not limit for maximum diameter of hole
Surface Finishing Thickness	gold plating：Ni 2.5-5um,  Au: 0.025－0.075um
	immersion gold: Ni 3-6um, Au: 0.025-0.1um
	HAL(LF): 3-30um
V－cut Angle tolerance	±5°
V-cut Range	0.3mm-4.5mm
Smallest silkscreen height	0.15mm
Smallest PAD	0.1mm

How to Get a Quote for Copper Multilayer PCB Project?

Essential Documentation for Copper Multilayer PCB Quotation

• Lamination Stackup Drawing: Specify layer materials (e.g., FR-4/Rogers 4350), copper thickness (1–6OZ), dielectric thickness (mm), and impedance control targets.
• Gerber Files: Include circuit layers, drilling layers, and solder mask layers. Annotate trace width/spacing (e.g., 4/4mil), blind/buried via positions, and hole tolerance (±0.05mm).
• PCB Technical Parameter Sheet: Board dimensions (L×W×T), layer count (e.g., 8L), surface finish (ENIG/OSP), and special processes (via plating/half-hole).
• Impedance Control Requirements: Define differential pair impedance (e.g., 100Ω±10%), reference layers, and testing methods.
• Acceptance Criteria: Specify IPC class (e.g., IPC-6012 Class 3) and testing items (flying probe/AOI/X-ray).
• Quantity & Lead Time: Prototype/batch quantity (e.g., 5pcs/1k) and desired delivery timeline (e.g., 7-day expedited).
• Special Requirements: High-frequency/thermal needs (e.g., PTFE hybrid), environmental certifications (RoHS/UL).

Why Partner with Best Technology?

• Expertise: Handles 16+ layer thick copper (6OZ) and hybrid high-frequency boards.
• Speed: Offers 48-hour quick quotes and complimentary impedance calculation.
• Quality: Free DFM review to eliminate design flaws upfront.
• Result: Avoid cost overruns, accelerate time-to-market, and ensure compliance for demanding applications.

Welcome to contact us if you have any request for copper multilayer PCB: sales@bestpcbs.com.