Overview

An etched copper lead frame is produced by photochemical machining rather than stamping, which is why it holds finer leads, no sheared burr and, above all, better coplanarity. C19400, C7025 or CuFe2P copper alloy strip from 0.10 mm to 0.40 mm is laminated, exposed on both faces and etched into a die pad, leads, tie bars and dam bars in one cycle. Coplanarity of the lead tips, typically held within 0.05 mm, is the figure that decides whether wire bonds and molded packages seat correctly during assembly.

Buyers pick an etched copper lead frame for fine-pitch, high-I/O or thin packages where a stamped burr and die-induced warp cause bent leads and poor mold adhesion. Half-etching thins the die pad and lead tips to a controlled remaining gauge, while selective Ni/Pd/Au or silver plating is applied only where the die and wires attach. Because the tool is a film, a new pinout or pad size is a low-cost revision, and the same artwork reproduces identical lead geometry from a prototype strip to volume reels for automated die attach and molding.

Parameter Window

• Available Materials: C19400, C7025, CuFe2P, KFC/EFTEC and C1100 copper alloys
• Material Thickness Range: 0.10–0.40 mm (0.15–0.25 mm typical for QFN/QFP and power packages)
• Tolerance: ±0.02 mm on lead width, ±0.01 mm on half-etch remaining gauge, coplanarity ≤0.05 mm
• Minimum Feature: 0.08 mm lead width, 0.15 mm pitch, 0.10 mm half-etch land
• Surface Options: selective Ni/Pd/Au or Ag plating on pad and lead tips, roughened pad, anti-tarnish, reel or strip packing
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Package Review — Check pin count, pitch, die-pad size and coplanarity target against the chosen copper gauge.
2. Material Selection — Certify C19400/C7025 gauge, temper and rolling direction before lamination.
3. Cleaning & Lamination — Degrease and laminate dry film on both faces so fine leads are fully masked.
4. Dual-Side Exposure — Register front and back artwork to shared fiducials, defining leads, pad, tie bars and dam bars.
5. Development — Develop both sides and inspect narrow leads for resist loss or bridging before etching.
6. Half-Etch & Through Etching — Time the etch to thin the die pad and lead tips while cutting leads fully through the strip.
7. Selective Plating — Strip resist, then spot-plate Ni/Pd/Au or Ag only on the die attach and wire-bond areas.
8. Coplanarity & Reel Pack — Measure lead-tip coplanarity and profile against the approved article, then reel or tray-pack with a lot record.

Core Advantages

1. Superior coplanarity: Chemical removal adds no die-induced warp, so lead tips stay within 0.05 mm and seat evenly in the mold.
2. Fine-pitch capability: An etched copper lead frame holds 0.08 mm leads and 0.15 mm pitch that stamping struggles to keep straight.
3. Burr-free leads: No sheared edge means fewer bent pins, less mold flash and cleaner wire-bond surfaces.
4. Tooling-free pinouts: A new pad or lead layout is a new film, making prototype and revision runs economical.
5. Integrated half-etch features: Die pads, lead tips and tie bars are thinned in the same cycle as the through-cut leads.
6. Selective plating: Precise plating masks place precious metal only where bonding occurs, cutting material cost.

Typical Applications

• QFN and DFN packages: Leadless frames where pad flatness controls mold and thermal performance.
• QFP and SOP/TSOP: Fine-pitch gull-wing lead arrays for logic and memory devices.
• Power IC and MOSFET: Thicker copper frames with roughened pads for high-current die attach.
• LED lead frames: Reflective plated pads and tightly coplanar leads for emitter packaging.
• MEMS and sensor packages: Small, low-stress frames for delicate sensing dies.
• IC substrate and interposer strips: Registered lead arrays for multi-die and 2.5D assemblies.

Design Notes & Process Considerations

1. Coplanarity specification: State the measurement method and allowable lead-tip offset, since warped leads cause open bonds and mold voids.
2. Side-etch compensation: Bias lead width and pitch artwork by roughly one material thickness of lateral undercut per side.
3. Half-etch remaining gauge: Specify remaining thickness on the die pad and lead tips, not just removed depth.
4. Plating area definition: Draw the plating mask explicitly so Ni/Pd/Au or Ag lands only on bond and attach zones.
5. Grain direction and warp: Note rolling direction and request stress relief, as anisotropy in copper strip bows long lead arrays.
6. Strip handling: An etched copper lead frame drawing should define tie bars, dam bars and reel or tray packing for automated molding.