Overview

A leadframe etching service produces leadframes, lead tips, dam bars and die pads by photochemical machining instead of progressive stamping. The strip is laminated with resist, imaged with the lead pattern, developed, and etched from both faces, so the pattern is cut by chemistry at a rate that is uniform across the panel. Because there is no die, a new package outline, a revised lead count or an extra tie bar is an artwork change: prototypes and low-volume package variants no longer wait for a tool build, and the first lot can be produced while a stamping tool is still being quoted.

Fine pitch is where the process earns its place. Lead width and gap at 0.05 mm can be held without the sliver and burr problems that appear when a stamping punch gets close to strip thickness, and half-etched features such as down-sets and bend lines are produced by controlling depth rather than by coining. Copper alloys C194 and C7025 cover most requirements, alloy 42 is used where low expansion matters, and 304/316L stainless appears in special carriers. Strip is normally 0.1 mm to 0.5 mm and can be supplied in tape and reel for pick-and-place assembly. That is why a leadframe etching service is usually the first quotation for a new package, and often stays the production route once volumes settle.

Parameter Window

• Available Materials: copper C194, copper C7025, alloy 42 (FeNi42), 304/316L stainless steel
• Material Thickness Range: 0.1–0.5 mm
• Tolerance: ±0.05 mm on lead tip position, ±0.01 mm on lead width at fine pitch
• Minimum Feature: 0.05 mm lead width and gap with 0.1 mm pitch at 0.15 mm strip
• Surface Options: selective silver or gold plating, nickel underplate, half-etch down-set, laser mark, tape and reel
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Package Review — Read the package drawing, confirm lead count, pitch, down-set depth and die pad size against etchable limits.
2. Strip Selection — Choose copper alloy and temper for conductivity, strength and plating compatibility, and confirm camber before release.
3. Lamination — Clean the strip and apply resist on both faces, keeping registration holes clear for the exposure fixture.
4. Double-Side Exposure — Image top and bottom patterns to the same datum so lead walls stay aligned through the thickness.
5. Develop — Open lead and window areas, inspect fine-pitch gaps under magnification before the strip enters the bath.
6. Controlled Etch — Etch both faces at matched rates; half-etch depth for down-sets is set by dwell and confirmed on a coupon.
7. Strip & Plate — Remove resist, then apply selective silver or gold on lead tips and die pad, with masking on areas that must stay bare.
8. Inspect & Reel — Check lead width, pitch, down-set depth and camber, then tape and reel with a first-article report.

Core Advantages

1. No tooling cost: A new lead count or package outline is a new film, so low-volume and prototype packages avoid a five-figure die.
2. Fine pitch without slivers: Chemical cutting holds 0.05 mm leads and gaps without the burr and sliver risk of a close-to-thickness punch.
3. Burr-free lead tips: Tips are clean and flat, so wire bonding and solder wetting behave consistently batch to batch.
4. Half-etch in the same pass: Down-sets, bend lines and recessed die pads are depth-controlled rather than coined, with no tool wear drift.
5. Short cycle for revisions: Design changes run in days rather than waiting for tool modification and re-qualification.
6. Strip-level consistency: All leads on the strip etch together, so lead width spread stays tight across the panel and between lots.

Typical Applications

• QFN and DFN leadframes: Fine-pitch etched frames with half-etched down-sets for compact power and RF packages.
• LED leadframes: Reflective cups and isolated pads produced without a stamping die for small production runs.
• Sensor and MEMS packages: Thin frames with open windows and precise die attach areas.
• Connector and contact strips: Etched contact fingers with uniform width for high-density connectors.
• Prototype and qualification builds: First silicon and package qualification lots that cannot justify tooling.
• Special carriers: 304/316L stainless carriers and process frames for handling and test fixtures.

Design Notes & Process Considerations

1. Design for isotropic etch: The bath cuts sideways as well as down, so lead width shrinks by roughly twice the etch depth; compensate in artwork.
2. Respect the aspect ratio: Keep feature width at least equal to strip thickness; at 0.5 mm strip, 0.05 mm leads are not realistic.
3. Define the down-set clearly: Give half-etch depth with a tolerance and state which face is etched, since depth drives die attach height.
4. Plan the tie bar: Tie bars must survive handling but be cuttable in assembly; agree the residual thickness with the assembly process.
5. Specify plating windows: Selective plating needs a mask drawing; unnamed areas will be plated or left bare by default.
6. Control camber before reel: Ask for camber limits per 100 mm and flat-pack or reel supply, because a bowed strip jams feeders.