Overview

Continuous reel-to-reel photochemical machining defines how much finished part area a line can hold to tolerance within a shift, and that figure is set by three linked variables: web width, line speed and usable coil length. A production line runs 250–650 mm wide coils of stainless steel 301/304/316L, copper C1100/C194 or nickel-iron Alloy 42 at 0.5–3.0 m/min through cleaning, lamination, exposure, developing, etching, stripping and rinsing stations. Since the stations are inline, the slowest step governs throughput, so experienced buyers judge roll to roll etching capacity by the sustained etch rate at the target feature size rather than by the nameplate speed of the unwinder.

Capacity is also yield over an entire coil, not just metres per minute. Ferric chloride or cupric chloride is held at fixed Baume, temperature and dissolved-metal load by automatic dosing, so the etch factor measured on the first metre of a 600 mm outer-diameter coil still applies on the last. Closed-loop tension, sprocket registration and splice detection keep cross-web position within ±0.05 mm across thousands of metres. When a program calls for millions of lead frames, encoder discs or shielding cans per month, that documented roll to roll etching capacity is what separates a qualified volume supplier from a prototyping job shop.

Parameter Window

• Available Materials: stainless steel 301/304/316L, copper C1100/C194, nickel and nickel-iron Alloy 42, supplied as continuous coil
• Material Thickness Range: 0.05–0.5 mm, with 0.08–0.2 mm the most stable window for fine pitch
• Tolerance: ±0.02 mm on etch-to-etch pitch, ±10% of stock on half-etch depth, ±0.05 mm cross-web registration
• Minimum Feature: 0.10 mm line and 0.15 mm hole at 0.10 mm stock; 0.20 mm line at 0.3 mm stock
• Surface Options: bright annealed, matte, selective Ni/Au plating, adhesive lamination, reel singulation or sheet cut
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Coil Qualification — Verify alloy, temper, width and gauge, then measure camber and residual stress so the web tracks straight through the line.
2. In-Line Cleaning — Degrease and micro-etch the moving web in a spray cleaner, then rinse and dry before resist enters the laminator.
3. Dry Film Lamination — Apply photoresist under controlled heat, pressure and web tension, with edge-bead trimmed so the film seats flat at coil edges.
4. Roll-to-Roll Exposure — Expose through registered film or direct laser imaging, indexing each frame to a punched sprocket hole for panel-level accuracy.
5. Development & Inspection — Develop the resist inline and scan for scumming or broken lines with a camera station before the web reaches etchant.
6. Controlled Etching — Spray ferric chloride or cupric chloride at fixed Baume, temperature and conveyor speed, dosing to hold etch factor across the coil.
7. Stripping & Finishing — Strip resist, neutralize, rinse, then plate, laminate adhesive or apply a protective film while still on the reel.
8. Reel Inspection & Slitting — Measure critical dimensions on sampled frames, log SPC data per coil, then slit to ordered width and rewind to specified core and outer diameter.

Core Advantages

1. Continuous throughput: One coil yields tens of thousands of parts without sheet load/unload cycles, so labour per piece falls as volume rises.
2. Stable chemistry: Auto-dosed etchant holds a constant etch factor and sidewall from the first metre to the last of a 600 mm coil.
3. Cross-web accuracy: Sprocket indexing and closed-loop tension keep features within ±0.05 mm over kilometres of web.
4. Gentle handling: Parts stay on the carrier web until singulation, so 0.05 mm foil never bends, scratches or nests in trays.
5. Linear scalability: Output rises with a second shift or a parallel line, with no new hard tooling for the same artwork.
6. Traceable coil data: Every reel leaves with its own SPC record, so planners schedule against a verified roll to roll etching capacity rather than an estimate.

Typical Applications

• Lead frame strips: High-volume etched lead frames delivered on reel for automated die attach and moulding.
• Encoder discs: Thin code wheels with fine slots slit from coil for motor feedback assemblies.
• EMI shielding cans: Foldable shield patterns half-etched on continuous stainless for board-level shielding.
• Contact springs: Reel-fed spring contacts for connectors, plated selectively before singulation.
• Fuel cell bipolar plates: Fine flow-field patterns etched in thin coil for stack assemblies.
• Adhesive-backed labels: Etched metal asset tags laminated with PSA and rewound for automatic dispensing.

Design Notes & Process Considerations

1. Gauge versus speed: Thinner stock etches faster but needs lower tension; fix line speed from the slowest feature, not the thickest gauge.
2. Coil geometry: Specify core ID, maximum outer diameter and splice policy, since a 600 mm coil cuts changeover losses sharply.
3. Registration marks: Add sprocket holes and fiducials in the web margin so every frame indexes to the same datum.
4. Etch factor compensation: State the expected undercut at the chosen gauge; artwork is oversized by that amount to hold final pitch.
5. Cross-web tolerance: Allow ±0.05 mm for web wander on long coils, tighter only where a secondary registration step exists.
6. Singulation plan: Decide whether the reel is slit, sheet-cut or left whole, because finishing must be inline to protect throughput.