ODM Copper Coin Embedded PCB Supplier & Factory

A Press-Fit Copper Coin is mechanically driven into a precision-routed cavity in the PCB after the multilayer lamination cycle has completed. The mechanical retention relies on friction, knurled coin edges, or conductive epoxy bonding. This approach avoids resin bleed and simplifies prototyping.

An Embedded (Buried) Copper Coin is positioned into the stackup prior to lamination and bonded during the primary hot-press vacuum cycle using low-flow prepregs. Buried coins can be completely covered by dielectric and inner copper layers or stepped (T-Coin) to reveal surface pads on specific layers, offering superior mechanical integrity and high planarity for dense packaging.

While plated thermal vias and VIPPO (Via-in-Pad Plated Over) improve standard FR-4 heat conduction, the aggregate thermal path remains constrained by the plating thickness (typically 20–35 μm of electrodeposited copper) and the surrounding epoxy matrix. This caps the overall effective conductivity of the via array at approximately 10 to 30 W/m·K.

In contrast, a solid copper coin is 100% C11000 electrolytic copper offering 398 W/m·K. For power densities above 25–30 W/cm² (common in GaN power modules and automotive traction drives), thermal via arrays experience thermal runaway, whereas embedded coins maintain junction temperatures within safe margins.

The most reliable surface finish is ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) or ENIG (Electroless Nickel Immersion Gold). ENEPIG provides an ultra-planar surface that prevents copper oxidation, resists multiple lead-free reflow cycles without gold embrittlement, and accommodates both solder joint interfaces and direct gold/aluminum wire bonding.

For high-frequency RF applications, Immersion Silver (IAg) or OSP may be selected to prevent high-frequency skin effect losses introduced by nickel barriers.

Soldering an electronic component thermal pad directly to a massive copper coin represents a major thermodynamic challenge because the coin acts as a heat sink, siphoning thermal energy away from the solder alloy. We mitigate this through three proven engineering controls:
1. Stencil Windowing: Rather than a single solid aperture, we segment the stencil pattern into a matrix of smaller squares (e.g., 60–70% total area coverage) allowing outgassing paths for flux volatiles.
2. Zoned Solder Profile: We extend the reflow soaking zone (soak time between 150°C and 200°C) to ensure the copper mass reaches thermal equilibrium before transitioning through liquidus (TAL).
3. Vacuum Vapor Phase / Nitrogen Reflow: For critical medical and automotive assemblies, we utilize nitrogen atmospheric or vacuum reflow systems to drive solder voiding below 10%, complying with IPC-A-610 Class 3.

Standard design guidelines require:

• Cavity to Copper Trace Clearance: Maintain a minimum of 0.25 mm (10 mil) between the edge of the milled cavity and the nearest non-ground inner/outer layer conductive traces.
• Coin Surface Coplanarity: Our factory holds standard coplanarity to ±15 μm (0.6 mil) relative to the surrounding outer laminate surface to avoid solder paste bridging or open joints.
• Coin Dimension Tolerance: CNC coin profiles are cut to ±0.05 mm tolerances to guarantee a snug press-fit without cracking adjacent prepreg resin walls.

Yes. We routinely manufacture boards with multiple disparate coin geometries, such as an array of smaller I-Coins situated under multiphase VRM MOSFETs paired with a larger stepped T-Coin under a primary GaN power module. Step-milling and depth-controlled CNC routing allow varied Z-axis depths across identical panels.

Each batch undergoing qualification is subjected to micro-sectioning analysis to inspect resin filling integrity around the coin perimeter. We conduct High-Potential (Hi-Pot) Electrical Testing to confirm electrical isolation between the coin and adjacent high-voltage circuitry (supporting test voltages up to 3,000V DC depending on dielectric thickness). Furthermore, accelerated thermal stress cycling (-40°C to +125°C for 500+ cycles) is executed during NPI qualification to verify crack resistance.

To provide a comprehensive DFM audit and quotation, please furnish:

• Gerber or ODB++ Files: Including layer stackup, drill files, and a dedicated layer indicating exact copper coin boundary coordinates and depths.
• BOM (Bill of Materials): Complete with exact manufacturer part numbers (MPNs), footprint descriptions, and reference designators.
• Mechanical Drawing: PDF drawing noting coin planarity limits, surface finish specifications (e.g., ENEPIG, ENIG), and coin alloy callouts (C11000 standard).
• Assembly & Test Requirements: SMT component centroid file (pick-and-place), functional circuit test (FCT) guidelines, and any specific X-ray void threshold requirements.