UGPCB Nickel-Palladium-Gold Double-Sided PCB – Product Overview

Panoramica del prodotto: What Is a Nickel-Palladium-Gold Double-Sided PCB?

A nickel-palladium-gold double-sided PCB (also known as an ENEPIG double-sided PCB) is a circuito stampato that features the Electroless Nickel Electroless Palladium Immersion Gold (Enepico) surface finish on both sides of the board. This advanced surface treatment builds upon the traditional double-sided PCB structure by adding a palladium layer between the nickel and gold deposits, creating a robust tri-layer composite finish that delivers superior solderability, wire bonding performance, and environmental stability.

UGPCB’s nickel-palladium-gold double-sided PCB uses Kingboard KB6160A FR-4 copper-clad laminate as the base material. The board measures 49.6 × 32.8 mm with a thickness of 1.6 mm and a copper foil thickness of 1 oz (circa 35 μm). The solder mask is green with white silkscreen characters. With a minimum aperture of 0.27 mm and a minimum line width/spacing of 0.27 × 0.3 mm, this ENEPIG PCB delivers precision manufacturing combined with high-quality surface finishing.

The nickel-palladium-gold PCB is widely recognized as a “universal surface finish” in the electronics industry. It serves a broad range of applications, comprese le telecomunicazioni, elettronica di consumo, controllo industriale, security systems, elettronica automobilistica, APRITENZE, smart home devices, Attrezzatura medica, and military/aerospace systems.

Key Technical Specifications

Parametro	Specifica
Laminato	Kingboard KB6160A FR-4
Spessore della scheda	1.6 mm
Numero di strati	A doppia faccia
Dimensione del consiglio	49.6 × 32.8 mm
Apertura minima	0.27 mm
Minimum Line Width/Spacing	0.27 × 0.3 mm
Spessore di lamina di rame	1 oz (≈35 μm)
Finitura superficiale	Nickel-Palladium-Gold (Enepico)
Maschera di saldatura / Legend	Green solder mask / White silkscreen

Laminate Details: KB6160A FR-4 Copper-Clad Laminate

KB6160A is a high-performance FR-4 copper-clad laminate manufactured by Kingboard Laminates Holdings Ltd. This material is specifically designed for standard double-sided printed wiring board (PWB) produzione. It complies with the IPC-4101/21 specification sheet. Key properties include:

• UV Blocking (UVB) capacità: Prevents light transmission during imaging, improving pattern transfer accuracy and yield
• Excellent dimensional stability: Ensures precision throughout the manufacturing process
• Superior heat resistance and mechanical properties: Meets high-reliability application requirements
• Temperatura di transizione vetrosa (Tg): 135° C. (DSC method)
• Temperatura di decomposizione termica (Td): 305° C. (TGA method)
• Asse Z CTE (α1/α2): 58 ppm/° C. (< Tg) / 286 ppm/° C. (> Tg)
• Costante dielettrica (Non so): 4.58
• Fattore di dissipazione (Df): 0.022
• Resistività al volume: 1 × 10⁸ MΩ-cm
• Assorbimento di umidità: 0.21%
• Punteggio di infiammabilità: UL94 V-0

(Data above are sourced from the Kingboard KB6160A Technical Data Sheet, with test methods per IPC-TM-650 series standards.)

The ENEPIG Surface Finish: A Detailed Explanation

What Is ENEPIG?

ENEPIG stands for Electroless Nickel Electroless Palladium Immersion Gold. It is an electroless chemical surface treatment that sequentially deposits three metal layers—nickel, palladio, and gold—onto the copper circuitry of a PCB.

The tri-layer structure of ENEPIG consists of:

• Bottom Layer – Electroless Nickel (In): Thickness of 3–5 μm. This layer acts as a diffusion barrier, preventing copper migration to the surface while providing mechanical support and a foundation for soldering.
• Middle Layer – Electroless Palladium (Pd): Thickness of 0.05–0.1 μm. This critical barrier layer prevents interaction between nickel and gold, eliminating galvanic corrosion.
• Top Layer – Immersion Gold (Au): Thickness of 0.03–0.05 μm. This thin layer provides excellent solderability and oxidation protection.

According to IPC-4556A (the latest 2025 revision), ENEPIG deposit thickness requirements are specified as follows:

• Nickel layer: 3 μm a 6 μm (measured at average ± 4σ)
• Palladium layer: 0.05 μm a 0.30 μm (measured at average ± 4σ)
• Gold layer: Minimum 0.030 μm, maximum 0.07 μm (measured at below average − 4σ)

(Thickness specifications above are based on IPC-4556A, Specification for Electroless Nickel/Electroless Palladium/Immersion Gold (Enepico) Plating for Printed Boards.)

The ENEPIG Process Flow

UGPCB’s nickel-palladium-gold double-sided PCBs follow a standardized electroless plating process:

Degreasing → Micro-etching → Pre-dipping → Activation → Electroless Nickel Plating → Electroless Palladium Plating → Immersion Gold Plating → Drying

Each process step includes multiple rinsing stages to ensure plating quality and adhesion. The chemical reactions involved include both oxidation-reduction reactions and displacement reactions.

Core Advantages of Nickel-Palladium-Gold Double-Sided PCBs

1. Complete Elimination of the “Black Pad” Defect

The ENIG (Oro per immersione in nichel chimico) process has long been plagued by the “Black Pad” defect—a condition where gold attack on the nickel layer leads to brittle solder joints and premature failure. ENEPIG solves this problem by introducing a palladium barrier layer between nickel and gold, preventing direct contact and eliminating grain boundary corrosion. Industry data shows that ENEPIG reduces black pad occurrences by nearly 90% compared to ENIG. Under extreme temperature cycling conditions, ENEPIG demonstrates up to 30% higher reliability than ENIG.

2. Superior Wire Bonding Capability

ENEPIG surface finishes offer excellent bonding performance for both gold and aluminum wires. The palladium layer widens the process window for gold wire bonding, enabling reliable wire bonds even with thinner gold deposits. In many applications, ENEPIG supports wire bonding strengths exceeding 10 grams for both gold and aluminum wire bonds. This makes nickel-palladium-gold double-sided PCBs particularly suitable for semiconductor packaging and hybrid assembly applications requiring wire bonding.

3. Excellent Solderability and Multiple Reflow Tolerance

ENEPIG surface finishes provide excellent solderability with both leaded and lead-free solders (including SAC305 alloy). ENEPIG-finished PCBs can withstand up to 10 reflow cycles without significant degradation.

4. Extended Shelf Life

Thanks to the protective palladium layer, ENEPIG surface finishes offer superior oxidation and corrosion resistance. This translates to a significantly longer shelf life compared to other surface finishes. According to IPC guidelines, ENEPIG surface finishes can achieve IPC Category 3 shelf life of at least twelve months.

5. Greater Design Flexibility

Unlike electrolytic nickel-gold processes, ENEPIG is an electroless process that requires no busbars or plating leads. This allows more boards to be processed simultaneously in the same plating bath, increasing overall throughput. Inoltre, ENEPIG imposes no routing restrictions, providing greater flexibility for high-density circuit designs.

How Nickel-Palladium-Gold Double-Sided PCBs Work

The Synergistic Action of Three Plating Layers

The exceptional performance of nickel-palladium-gold double-sided PCBs stems from the precise synergy of the three plating layers:

① Nickel Layer (Ni-P Alloy) – The Foundation Barrier

The nickel layer serves as the foundation of the ENEPIG structure. Its primary function is to block copper atom diffusion to the surface, preventing the formation of brittle Cu-Sn intermetallic compounds (IMC) during soldering or high-temperature exposure. Nickel thickness is typically controlled between 3–6 μm, with phosphorus content strictly maintained at 7–9% to balance hardness and corrosion resistance.

② Palladium Layer (Pd) – The Critical Barrier and Activation Layer

The palladium layer is the defining feature that distinguishes ENEPIG from ENIG. It acts as a “partition wall,” preventing migration and grain boundary corrosion between nickel and gold. The palladium layer must be thick enough to block nickel diffusion to the gold surface and prevent excessive corrosion of the electroless nickel deposit.

③ Gold Layer (Au) – Protection and Solderability

The thin outer gold layer protects the nickel from oxidation while providing low contact resistance and excellent solderability. Because the palladium layer provides isolation, the gold layer in ENEPIG can be made thinner (0.03–0.05 μm) without compromising reliability, which helps reduce material costs to some extent.

Classification of Nickel-Palladium-Gold Double-Sided PCBs

UGPCB’s nickel-palladium-gold double-sided PCB can be scientifically classified across multiple dimensions:

By Number of Layers

• PCB a doppia faccia: Conductive circuits are distributed on both sides of the substrate, with electrical connections established through plated through-holes (PTHS).

Per materiale di base

• FR-4 Epoxy Glass Fabric Laminate: Using Kingboard KB6160A, compliant with IPC-4101/21.

Per finitura superficiale

• Enepico (Elettroless Nickel Electroless Palladium Immersion Gold) : Tri-layer composite plating structure.

By Application Domain

• High-Reliability General-Purpose PCB: Suitable for telecommunications, elettronica automobilistica, dispositivi medici, aerospaziale, controllo industriale, e altro.

By Manufacturing Precision

• Precision PCB: Minimum aperture of 0.27 mm, minimum line width/spacing of 0.27 × 0.3 mm.

Flusso del processo di produzione

UGPCB’s nickel-palladium-gold double-sided PCB production follows a comprehensive manufacturing workflow:

Stage 1: Substrate Preparation

1. Material Cutting: KB6160A copper-clad laminate is cut to the required dimensions.
2. Perforazione: Mechanical drilling with a minimum aperture of 0.27 mm.
3. Electroless Copper Deposition & Panel Plating: Through-hole metallization.

Stage 2: Circuit Formation

4. Trasferimento del modello: Dry film lamination → Exposure → Development.
5. Acquaforte del circuito: Removal of excess copper to form the circuit pattern.
6. AOI (Ispezione ottica automatizzata) : Ensuring circuit accuracy.

Stage 3: Solder Mask and Legend

7. Solder Mask Printing: Green ink application to protect circuits and prevent solder bridging.
8. Legend Printing: White silkscreen characters.

Stage 4: Finitura superficiale (Enepico)

9. Sfuggente: Removal of surface contaminants.
10. Micro-Etching: Light etching of copper surface to enhance adhesion.
11. Pre-Dipping: Pretreatment before activation.
12. Attivazione: Deposition of catalytic palladium seed layer on copper.
13. Electroless Nickel Plating: Deposition of nickel layer (3–5 μm).
14. Electroless Palladium Plating: Deposition of palladium layer (0.05–0.1 μm).
15. Immersion Gold Plating: Deposition of gold layer (0.03–0.05 μm).
16. Asciugatura: Completion of surface finish.

Stage 5: Ispezione finale

17. Test elettrici: Ensuring electrical continuity and isolation.
18. Ispezione visiva: Checking surface quality.
19. Confezione & Spedizione.

Applicazioni tipiche

UGPCB’s nickel-palladium-gold double-sided PCBs are widely used across numerous industries:

Apparecchiature per le telecomunicazioni

• Base stations, router, interruttori
• High-frequency communication modules, RF devices

Elettronica automobilistica

• Engine Control Units (COPERTINA)
• In-vehicle infotainment systems
• Adas (Sistemi avanzati di assistenza alla guida)
• BMS (Battery Management Systems) for new energy vehicles

Dispositivi medici

• Medical implantable devices
• Diagnostic instruments, patient monitoring equipment

Aerospaziale & Difesa

• Spacecraft and satellite electronics
• Aviation control systems

Controllo industriale & Sicurezza

• Plc (Programmable Logic Controllers)
• Industrial motor drives
• Security and surveillance equipment

Elettronica di consumo & Casa intelligente

• Smartphone motherboards
• Smart home control modules
• Wearable devices

Military & Elettronica di potenza

• Military electronic systems
• Power modules, power converters

Why Choose UGPCB for Nickel-Palladium-Gold Double-Sided PCBs?

✅ IPC Standards Compliance

UGPCB’s nickel-palladium-gold double-sided PCBs are manufactured in strict accordance with IPC-4556A. The KB6160A laminate complies with IPC-4101/21, ensuring full standardization from base material to surface finish.

✅ Precision Manufacturing Capabilities

With a minimum aperture of 0.27 mm and minimum line width/spacing of 0.27 × 0.3 mm, UGPCB meets the demands of high-density interconnect (ISU) and fine-pitch component assembly.

✅ High-Reliability Assurance

ENEPIG surface finish reduces black pad defects by nearly 90% and delivers up to 30% higher reliability than ENIG under extreme temperature fluctuations. Products withstand multiple reflow cycles and meet J-STD-003 Category 3 durability requirements.

✅ Professional Technical Support

The UGPCB team provides full-process technical support, from Gerber file review and BOM optimization to PCBA assembly.

Inquiries & Ordering

Ready to turn your design into a high-quality nickel-palladium-gold double-sided PCB?

📧 Email: sales@ugpcb.com

📞 Phone: +86-135 4412 8719

🌐 Website: www.ugpcb.com

📋 Ordering Process:

1. Submit Gerber files, Distinta base, and design documentation.
2. UGPCB’s engineering team performs DFM (Progettazione per la produzione) revisione.
3. Order confirmation and delivery schedule.
4. Manufacturing and quality control.
5. Shipping and logistics tracking.

Se ne hai bisogno Prototipazione PCB or volume production, UGPCB is committed to delivering high-quality nickel-palladium-gold double-sided PCBs and professional technical services.

Data Source Declaration

The technical data and standard specifications cited in this document are sourced from the following authoritative organizations:

1. IPC-4556A: Specification for Electroless Nickel/Electroless Palladium/Immersion Gold (Enepico) Plating for Printed Boards (2025 revision)
2. IPC-4101/21: Specification for Base Materials for Rigid and Multilayer Printed Boards – the specification sheet applicable to KB6160A
3. Kingboard KB6160A Technical Data Sheet (Kingboard Laminates Holdings Ltd.)
4. IPC-TM-650: Test Methods Manual – the standard test methods used for material property measurements
5. J-STD-003: Solderability Tests for Printed Boards – the solderability testing standard
6. Ul94: Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances – flammability rating standard

All data cited above are sourced from the official standards and technical documents listed, ensuring accuracy and authority.