Overview

Custom lead frame etching produces semiconductor lead frames through photochemical machining instead of stamping. A dry-film resist is laminated onto copper C11000 or alloy 42 strip, UV-exposed through artwork that carries every lead, dam bar, die pad and tie bar, and the unprotected metal dissolves in a matched etchant. Because the pattern lives on film rather than in a progressive die, custom lead frame etching carries no tooling charge for a new package outline, and a design revision is simply new artwork. Stock runs from 0.05 mm to 0.5 mm strip, with lead pitch down to 0.3 mm and half-etch features held to ±0.01 mm depth control.

For semiconductor packaging the decisive points are edge quality and dimensional stability. Chemical removal leaves leads with no burrs, no work-hardened rims and no punch-shear taper, so plating builds evenly and no slivers break off during molding. Half-etch dimples, stand-offs and staggered pad levels are produced in the same pass as the through features, and the strip stays flat because etching removes metal equally from both sides. Frames leave the line ready for Ni/Pd/Au or matte-tin plating, forming and tape-and-reel packing, and the first article matches the ten-thousandth piece.

Parameter Window

• Available Materials: copper C11000/C19400, alloy 42 (Fe-Ni 42%), Kovar, phosphor bronze C5191
• Material Thickness Range: 0.05–0.5 mm lead frame strip
• Tolerance: outline ±0.03 mm; lead pitch ±0.02 mm; half-etch depth ±0.01 mm
• Minimum Feature: 0.05 mm lead width or gap on 0.1 mm strip; dam bar ≥ 0.15 mm
• Surface Options: matte tin, Ni/Pd/Au pre-plated strip, selective plating, half-etch dimples, tape-and-reel packing
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Drawing & DFM Review — Convert the frame drawing to film artwork, check lead pitch, dam bars and half-etch levels against strip thickness, and confirm plating margins.
2. Material Selection — Choose copper C11000/C19400 for conductivity or alloy 42 for thermal expansion match with ceramic and silicon, and verify temper and strip flatness.
3. Cleaning & Lamination — Degrease the strip and laminate dry-film resist under controlled heat and pressure so fine leads sit on bubble-free film.
4. UV Exposure — Expose through high-resolution artwork registered to strip edges and pilot holes, holding lead position across the full panel length.
5. Development — Wash out unexposed resist to open leads, tie bars and die-pad outlines, then inspect dam bars for pinholes or residual film.
6. Etching — Spray ferric chloride from both sides; line speed, temperature and spray pressure hold lead width, pitch and half-etch depth within tolerance.
7. Stripping & Plating Prep — Strip resist, neutralize and dry, then route frames to Ni/Pd/Au or matte-tin plating, or to forming and downset stations.
8. Inspection & Packaging — Verify pitch, lead width, half-etch depth, burr condition and warpage against the approved sample, then pack on tape and reel.

Core Advantages

1. No stamping dies: Every package outline is artwork only, so prototypes and revisions skip die cost and months of tooling lead time.
2. Fine pitch without burrs: Leads at 0.3 mm pitch hold width and gap cleanly, and burr-free edges keep plating thickness uniform across the frame.
3. Half-etch features in one pass: Die-attach dimples, stand-offs and staggered pad levels are etched to ±0.01 mm depth beside the through features.
4. Stress-free, flat strip: Chemical removal leaves no work hardening, so frames stay flat for automated plating, molding and tape-and-reel handling.
5. Copper and alloy 42 on one line: High-conductivity copper and expansion-matched Fe-Ni 42 run through the same process window and inspection scheme.
6. Fast path from artwork to plated strip: Custom lead frame etching moves a design from drawing to plated samples without tooling, which suits new package qualification and small pilot lots.

Typical Applications

• QFP and QFN lead frames: Fine-pitch peripheral leads with etched dam bars and tie bars for plastic-molded surface-mount packages.
• Power and discrete device frames: Thick copper frames with wide die pads and heavy leads for MOSFETs, diodes and voltage regulators.
• MEMS and sensor package lids: Etched cavity lids and sealing frames with controlled standoff heights for pressure and inertial sensors.
• RF and microwave packages: Alloy 42 frames with stable pitch and flat sealing surfaces for hermetic ceramic packages.
• LED and optoelectronic frames: Reflector pads, thermal spreaders and lead arrays etched in one sheet for lighting and optical modules.
• Automotive semiconductor frames: Burr-free lead frames with full material traceability for control units and power electronics.

Design Notes & Process Considerations

1. Pitch versus thickness: Keep lead width at or above strip thickness for through-etching; 0.3 mm pitch on 0.1 mm strip is a practical floor for stable leads.
2. Half-etch depth control: Call out half-etch depth in millimetres rather than as a percentage, and hold it to ±0.01 mm where downset or standoff matters.
3. Etch compensation: Sidewalls taper roughly half the etch depth per side, so oversize lead widths in artwork whenever plating buildup will be added later.
4. Dam and tie bar geometry: Hold dam bars at 0.15 mm or more and keep tie bars symmetric so the frame separates cleanly after molding.
5. Warpage management: Balance copper removal on both faces and keep pad layouts symmetric to limit strip bow across the panel length.
6. Plating and packing: Specify contact plating and tape orientation up front — custom lead frame etching leaves burr-free edges, so plating adheres evenly across the frame.