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

Présentation du produit: 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 circuit imprimé that features the Electroless Nickel Electroless Palladium Immersion Gold (Énipique) 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 once (environ 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, including telecommunications, électronique grand public, contrôle industriel, systèmes de sécurité, électronique automobile, alimentations, smart home devices, équipement médical, and military/aerospace systems.

Principales spécifications techniques

Paramètre	Spécification
Stratifié	Kingboard KB6160A FR-4
Épaisseur du panneau	1.6 mm
Nombre de couches	Double face
Taille du conseil	49.6 × 32.8 mm
Ouverture minimale	0.27 mm
Largeur/espacement minimum des lignes	0.27 × 0.3 mm
Épaisseur de la feuille de cuivre	1 once (≈35 μm)
Finition de surface	Nickel-Palladium-Gold (Énipique)
Masque de soudure / Légende	Masque de soudure vert / 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 (PTB) fabrication. It complies with the IPC-4101/21 specification sheet. Key properties include:

• UV Blocking (UVB) capacité: Prevents light transmission during imaging, improving pattern transfer accuracy and yield
• Excellente stabilité dimensionnelle: Ensures precision throughout the manufacturing process
• Superior heat resistance and mechanical properties: Meets high-reliability application requirements
• Température de transition du verre (Tg): 135° C (DSC method)
• Température de décomposition thermique (Td): 305° C (TGA method)
• Axe Z CTE (A1 / A2): 58 ppm/°C (< Tg) / 286 ppm/°C (> Tg)
• Constante diélectrique (Ne sait pas): 4.58
• Facteur de dissipation (Df): 0.022
• Résistivité du volume: 1 × 10⁸ MΩ-cm
• Absorption d'humidité: 0.21%
• Cote d'inflammabilité: UL94V-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, palladium, and gold—onto the copper circuitry of a PCB.

The tri-layer structure of ENEPIG consists of:

• Bottom Layer – Electroless Nickel (Dans): 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:

• Couche de nickel: 3 μm à 6 µm (measured at average ± 4σ)
• Palladium layer: 0.05 μm à 0.30 µm (measured at average ± 4σ)
• Couche d'or: 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 (Énipique) 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 (Or par immersion au nickel autocatalytique) 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. En plus, 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 double face: Conductive circuits are distributed on both sides of the substrate, with electrical connections established through plated through-holes (PTH).

Par matériau de base

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

Par finition de surface

• Énipique (Nickel électrolaire à l'immersion du palladium électrolaire) : Tri-layer composite plating structure.

By Application Domain

• High-Reliability General-Purpose PCB: Suitable for telecommunications, électronique automobile, dispositifs médicaux, aérospatial, contrôle industriel, et plus.

By Manufacturing Precision

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

Flux de processus de fabrication

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. Forage: Mechanical drilling with a minimum aperture of 0.27 mm.
3. Electroless Copper Deposition & Panel Plating: Through-hole metallization.

Stage 2: Circuit Formation

4. Transfert de motif: Dry film lamination → Exposure → Development.
5. Gravure du circuit: Removal of excess copper to form the circuit pattern.
6. Zone d'intérêt (Inspection optique automatisée) : Ensuring circuit accuracy.

Stage 3: Masque de soudure et légende

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

Stage 4: Finition de surface (Énipique)

9. Dégraissage: Removal of surface contaminants.
10. Micro-Etching: Light etching of copper surface to enhance adhesion.
11. Pre-Dipping: Pretreatment before activation.
12. Activation: 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. Séchage: Completion of surface finish.

Stage 5: Inspection finale

17. Tests électriques: Ensuring electrical continuity and isolation.
18. Inspection visuelle: Checking surface quality.
19. Conditionnement & Expédition.

Applications typiques

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

Équipement de télécommunications

• Stations aval, routeurs, commutateurs
• High-frequency communication modules, RF devices

Électronique automobile

• Unités de commande du moteur (COUVERTURE)
• In-vehicle infotainment systems
• Adas (Systèmes avancés d’aide à la conduite)
• Bms (Systèmes de gestion de batterie) for new energy vehicles

Dispositifs médicaux

• Medical implantable devices
• Diagnostic instruments, équipement de surveillance des patients

Aérospatial & Défense

• Spacecraft and satellite electronics
• Aviation control systems

Contrôle industriel & Sécurité

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

Electronique grand public & Maison intelligente

• Smartphone motherboards
• Smart home control modules
• Wearable devices

Militaire & Électronique de puissance

• Military electronic systems
• Modules de puissance, 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 (IDH) 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 Catégorie 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, Nomenclature, and design documentation.
2. UGPCB’s engineering team performs DFM (Conception de la fabrication) revoir.
3. Order confirmation and delivery schedule.
4. Manufacturing and quality control.
5. Shipping and logistics tracking.

Whether you need Prototypage 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 (Énipique) 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.