Overview

Nickel lead frame etching produces the fine-pitch lead arrays that carry signals from a semiconductor die to the package board, using nickel, nickel-iron Alloy 42 or nickel-clad copper strip between 0.10 and 0.25 mm. Photochemical machining opens lead widths down to 0.15 mm with gaps near 0.15 mm and a positional tolerance around ±0.02 mm, and half-etched bond pads or dam bars are formed in the same bath. Because the metal is dissolved rather than stamped, the thin leads leave the line flat and burr-free, with no work-hardened edge to crack during forming. This route suits high-I/O packages where a progressive die would be too costly or too coarse at this pitch.

Solderability and wire-bondability are specified as carefully as pitch. After stripping, the lead tips and die pad receive selective Ni/Au, Ni/Pd/Au or silver plating, applied on reel so the bond shelf stays clean and oxide-free. Half-etch depth sets how the dam bar breaks after moulding, and closed-loop tension keeps a 0.15 mm lead from wandering across a long coil. For QFN, DFN and fine-pitch leaded packages, nickel lead frame etching is chosen because it holds fine geometry and a plating-ready surface in one continuous, reel-fed process.

Parameter Window

• Available Materials: nickel 200/201, nickel-iron Alloy 42, nickel-clad copper, Kovar on request
• Material Thickness Range: 0.10–0.25 mm, with 0.15–0.20 mm typical for fine-pitch frames
• Tolerance: ±0.02 mm on lead width and pitch, ±0.01 mm on half-etch depth, flatness <=0.05 mm per 100 mm
• Minimum Feature: 0.15 mm lead width, 0.15 mm gap, 0.20 mm bond pad at 0.15 mm stock
• Surface Options: selective Ni/Au, Ni/Pd/Au, silver spot plating, roughened die pad, reel or sheet delivery
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Package & Pitch Review — Import the die pad and lead map, then set lead width, gap and half-etch depth for the package type.
2. Alloy Selection — Pick nickel or Alloy 42 for thermal expansion match, and confirm strip gauge and flatness before imaging.
3. Cleaning & Lamination — Laminate dry film on both faces of the continuous strip so leads etch symmetrically.
4. Dual-Side Exposure — Expose front and back artwork in register, indexing half-etched bond pads and dam bars to the lead array.
5. Development — Develop both faces and inspect narrow lead gaps for scumming that would short two adjacent leads.
6. Controlled Etching — Spray nickel-compatible etchant at fixed Baume and temperature to open leads and stop half-etch zones on depth.
7. Selective Plating — Strip resist, then plate lead tips and die pads with Ni/Au, Ni/Pd/Au or silver on reel.
8. Reel Inspection — Verify lead width, pitch, half-etch depth and plating thickness, then rewind with interleaf for automated assembly.

Core Advantages

1. Fine pitch without dies: 0.15 mm leads and gaps are cut from artwork alone, so a progressive stamping die is unnecessary.
2. Flat, burr-free leads: Chemical removal leaves no roll-over, so leads do not crack during trim and form or short in moulding.
3. Half-etch features: Bond pads, dam bars and roughened die pads are formed in the same bath, saving a separate step.
4. Plating-ready surface: Selective Ni/Au or silver plating is applied on reel, keeping bond shelves oxide-free for wire bonding.
5. Reel-to-reel consistency: Closed-loop tension holds ±0.02 mm pitch across thousands of frames on a continuous coil.
6. Packaging yield: A controlled nickel lead frame etching line delivers geometry and solderability together, reducing assembly fallout.

Typical Applications

• QFN and DFN frames: Leadless pad arrays with half-etched dam bars for moulded near-chip-scale packages.
• Fine-pitch leaded packages: SOIC, TSSOP and QFP-style lead arrays down to 0.15 mm pitch.
• LED lead frames: Silver-plated pads for high-brightness LED packages, roughened for die-attach adhesion.
• Power device frames: Nickel-plated copper-clad frames for discrete power packages with heavy die pads.
• Sensor and MEMS packages: Small frames with fine bond pads for pressure, inertial and optical sensors.
• RF and optoelectronic frames: Low-stress nickel-iron frames where thermal expansion match matters.

Design Notes & Process Considerations

1. Pitch from package: Fix lead width and gap from the package outline and I/O count first, then add the etch factor to the artwork.
2. Half-etch depth: State dam-bar and bond-pad depth as a fraction of thickness, since it controls how the bar breaks after moulding.
3. Alloy and expansion: Choose nickel or Alloy 42 for the coefficient of thermal expansion match to the die and mould compound.
4. Plating map: Give a clear selective-plating map with metal, thickness and coverage, so bond shelves and outer leads are not mixed.
5. Flatness and coplanarity: Require flatness per 100 mm and lead coplanarity, or fine leads will not seat on the board during reflow.
6. Reel geometry: Specify core ID, outer diameter and splice policy, because handling a 0.15 mm lead array in sheets invites bending.