Overview

Titanium fuel cell bipolar plate photo chemical etching shapes the fine flow-field channels of metal bipolar plates from thin TA1/TA2/TC4 titanium foil in a chemical step instead of stamping or machining. Dry-film resist is laminated to both faces, the channel network is imaged with LDI double-sided registration, and the unprotected titanium is dissolved to a controlled depth, so parallel flow channels, ribs and manifold openings all form together as half-etched features. Because removal is chemical rather than mechanical, the plate stays flat and burr-free with no heat-affected zone, preserving the corrosion resistance and low density that make titanium a fit for hydrogen fuel cell stacks.

For stack and design engineers, photo chemical etching addresses three limits of formed or machined plates: press tooling is slow to revise for a dense serpentine flow field, machining struggles to hold a uniform channel depth across a large thin sheet, and stamping can warp the seal land that must stay flat for the gasket. Because the geometry lives in the artwork, a new channel layout is only a new data set, and every plate on a panel etches at the same rate, so channel depth, rib width and half-etched step consistency carry from the first test stack sample to volume. Etching also lets multiple layers be joined later by diffusion bonding into a closed multi-channel plate.

Parameter Window

• Available Materials: TA1 / TA2 commercially pure titanium and TC4 (Ti-6Al-4V) titanium alloy foil, selected for corrosion resistance and light weight in hydrogen service
• Material Thickness Range: 0.01–2.0 mm; stock above 1.0 mm is commonly used when the design calls for half-etched flow channels and local step thinning
• Tolerance: dimensional tolerance scales with material thickness and is for reference only — actual accuracy depends on the part structure, channel depth-to-width ratio and feature layout
• Minimum Feature: channel width, rib and manifold geometry are defined in the LDI artwork rather than by tooling; fine limits are confirmed at artwork review against foil thickness and half-etch depth
• Surface Options: as-etched bright surface, cleaned and passivated finish, protective film, and diffusion-bonded multi-layer stacks with enclosed flow channels
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork Review — Convert the stack 2D flow-field file into vector channel outlines, and check rib width, channel depth-to-width ratio and manifold positions against foil thickness.
2. Material Prep — Select TA1 / TA2 / TC4 foil by corrosion and strength needs, shear to panel size, and inspect both faces for scratches or rolled-in defects.
3. Cleaning & Lamination — Degrease and de-oxidize the titanium, then hot-roll dry film onto both faces with pressure matched to film thickness so no bubbles sit under narrow channels.
4. LDI Double-Sided Exposure — Write the channel pattern directly with laser direct imaging on both faces, holding front-to-back registration so inlet and outlet manifolds stay aligned.
5. Development — Wash away unexposed resist to open the areas to be dissolved, and rework any channel that still shows residual resist before etching.
6. Controlled Etching — Spray chemistry matched to the titanium grade; time, temperature and conveyor speed govern the photo chemical etching depth, sidewall and half-etched step across the panel.
7. Stripping & Diffusion Bonding — Remove resist and neutralize, then diffusion-bond two or more etched layers into a closed multi-channel plate where the stack design requires internal flow paths.
8. AOI / Flash Inspection — Verify channel depth, rib width, seal-land flatness and outline against the approved sample by AOI and flash measurement, then pack with first-article data.

Core Advantages

1. Corrosion resistance preserved: Chemical removal adds no heat tint or work hardening, so titanium keeps the passive film that resists the acidic, humid stack environment.
2. Light weight with thin sections: Foil within the process window gives a low-mass plate, which matters where stacks are counted by weight and volume.
3. Consistent flow-field depth: Every plate on a panel etches at the same rate, so half-etched channel depth and rib geometry stay uniform for even reactant distribution.
4. Flat seal lands: No mechanical force or roll-over means the gasket sealing area stays planar, reducing leak risk when the stack is clamped.
5. Half-etched channels in one pass: Channels, manifold steps and local thinning form in the same etch, avoiding secondary machining on thin, springy titanium.
6. Multi-layer plates by diffusion bonding: Two etched skins can be bonded into a closed plate with internal coolant channels, all from the same stress-free photo chemical etching route.

Typical Applications

• PEM fuel cell bipolar plates: TA1 half-etched flow fields that distribute hydrogen and air across the active area of a proton-exchange-membrane cell.
• Test and prototype stacks: Small-batch plates for single-cell and short-stack validation, where a new channel layout is only a new artwork.
• Electrolyser separator plates: Corrosion-resistant titanium flow plates for water-electrolysis cells exposed to oxidizing media.
• Diffusion-bonded cooling plates: Multi-layer titanium stacks with enclosed coolant channels for compact thermal management.
• Metallic flow-field distributor plates: Uniform channel networks that feed reactant gas evenly over large active areas.
• Lightweight portable power plates: Thin titanium bipolar plates where low mass and corrosion resistance outweigh raw conductivity.

Design Notes & Process Considerations

1. Channel depth-to-width ratio: Set channel depth as a share of foil thickness and keep the ratio moderate, so half-etched channels develop evenly without undercut narrowing the ribs.
2. Seal-land flatness: Keep a resist-covered, unetched sealing band around the flow field, and specify planarity for the gasket area rather than only the outline.
3. Half-etch depth callout: Give target depth and tolerance for flow channels and manifold steps; the achievable value depends on foil thickness and part structure.
4. Manifold and rib layout: Round internal corners in the artwork and avoid isolated narrow ribs, which are the first to distort during etching on thin titanium.
5. Diffusion-bond stack-up: If a closed plate is needed, align bonding pads and channel mirrors on both layers at the artwork stage to keep internal paths open after bonding.
6. Complete drawing data: State titanium grade, foil thickness, channel depth, sealing band, surface finish and bonding needs together to cut back-and-forth confirmation.