Chemical etching is a mature subtractive manufacturing process for metal bipolar plates used in proton exchange membrane fuel cells. The process accurately carves intricate flow field channels on thin metal foils without mechanical stamping force, eliminating material springback, deformation and residual stress that commonly occur in traditional forming methods.

Process Flow

1. Material preparation: Thin metal foils such as 316L stainless steel, titanium, nickel alloy and coated metal substrates are selected.
2. Surface pretreatment: Degreasing and oxide removal to achieve clean surface for photoresist bonding.
3. Dry film lamination: Cover both sides of the metal sheet with photoresist film.
4. UV exposure & development: Transfer custom flow channel patterns by UV exposure; remove unexposed photoresist to expose the areas for etching.
5. Chemical etching: Controlled etchant spray removes metal selectively to form precise gas flow channels, distribution manifolds and sealing grooves.
6. Photoresist stripping: Strip off remaining protective film after etching completion.
7. Post-treatment: Surface passivation, coating (gold, carbon or conductive coating) and cleaning for corrosion resistance and low contact resistance.
8. Dimensional & performance inspection: Check channel depth, width, flatness, leakage and surface quality.

Core Advantages

• Complex flow channel geometry can be realized in one processing step.
• Zero burr and residual stress, no material springback.
• Consistent channel depth and width across the entire plate surface.
• Suitable for ultra-thin metal substrates, reducing stack weight and volume.
• Flexible design iteration; low-cost prototyping without hard moulds.
• Uniform surface finish, good foundation for subsequent conductive coating.

Application Fields

• Hydrogen proton exchange membrane fuel cells (PEMFC)
• Portable fuel cell power systems
• Automotive fuel cell stacks
• Stationary distributed power generation
• Aerospace and backup power fuel cell modules

Design Notes

• Channel depth, rib width and channel width should follow chemical etching design rules.
• Symmetrical double-sided channel structure is available for bipolar plates.
• Material selection must balance conductivity, corrosion resistance and cost.
• Flatness control is critical to guarantee tight stacking and low contact resistance in fuel cell stacks.
• Conductive coating is usually required to improve surface performance for long-time operation.