Half Etched 316L Stainless Steel Flow Field Plate Depth Controlled Channels for PEM Fuel Cell Stacks

Half Etched 316L Stainless Steel Flow Field Plate Depth Controlled Channels for PEM Fuel Cell Stacks

Xinhaisen etches flow field plates to customer drawing. The channel field, manifold ports and sealing land are formed in one photochemical operation, so the plate leaves the line with open channels, a flat face for the gasket and no shear burr on the channel edge.

The plate is a half-etched part rather than a through-cut part: the channel depth is set by the etch dwell time on each face, and the remaining web under the channel stays as the structural base of the plate. This is the feature the product is built around, and it is why the depth has to be agreed on the drawing before the phototool is made.

How The Channel Field Is Etched

• Photoresist is laminated on one or both faces of the sheet and exposed through a phototool carrying the channel layout.
• Etchant is sprayed on the exposed areas, so channel depth is driven by dwell time and channel width is driven by the artwork and the side-wall undercut of the process.
• Single-side etching leaves a flat face on the opposite side; double-side etching produces a channel field on both faces.
• Stepped features, such as a shallower distribution channel feeding a deeper active channel, are produced by staged etching with a second mask step.
• The process is non-contact, so the plate is not stretched, coined or left with mechanical stress, and no die is cut for the layout.
• If the flow field is revised during stack testing, the change is made in the artwork and a new phototool, not in hard tooling.

Depth, Width And Flatness

Channel depth and channel width are reviewed together against material thickness. A channel that etches cleanly in a thin foil needs a different dwell time and a wider land in heavier sheet, and a depth-to-width ratio that closes the channel on one plate will not transfer unchanged to another thickness. Sealing land is kept as a solid band around the active area so the gasket has a continuous flat mating face, manifold ports are checked against the gasket drawing, and sharp internal corners at channel turns are replaced by a small radius so the flow path stays open. Where the plate is thin, carrier tabs and a frame keep the part flat until it reaches the stack, and flatness is inspected before packing.

Service Capability

Surface And Assembly Options

Plates can be supplied as etched, passivated, or with a surface treatment agreed for the stack. Where the programme calls for a finished assembly, plating and diffusion welding are handled as related processes against the same drawing set, so the channel field and the joint area are defined together rather than in two separate orders.

Where The Plates Are Used

• PEM fuel cell stacks for transport, portable power and stationary units
• PEM water electrolyzers for hydrogen production
• Laboratory and single-cell electrochemical test hardware
• Microchannel plates for compact heat exchange and fluid distribution

What We Review With Each Drawing

Channel width against material thickness and target depth, the width and continuity of the sealing land, manifold port position against the gasket, corner radii at channel turns, and the position of carrier tabs where the plate is thin. Points that cannot be held in the process are raised before the phototool is made, so the plate that reaches the stack test matches the drawing that was quoted.

From Drawing To Delivery

1. Drawing review. Channel geometry, depth target, sealing land and manifold layout are checked against thickness and tolerance, and we reply with feasibility comments and a quotation.

2. Phototool and first article. Artwork is converted to a phototool and a first article is etched for your fit, flow and leak test, with material certificate and inspection data.

3. Approval and production. Once the first article is approved the process parameters for that plate are fixed and the etch values are held under process control for the run.

4. Inspection and packing. Plates are checked against the drawing, inspected visually and for flatness, and packed interleaved to protect the channel field in transit.

Quality System

The plant is certified to ISO 9001, ISO 14001 and IATF 16949. Incoming material is inspected before production and finished plates are inspected before shipment, so each batch is released against the agreed drawing and inspection plan.

Frequently Asked Questions

Which material suits a flow field plate?
316L stainless steel is the usual starting point for corrosion resistance and cost, and titanium is chosen where the plate needs a higher strength-to-weight ratio or a different corrosion envelope. The final choice follows the medium, the operating temperature and the coating plan of your stack.

How is the channel depth controlled?
Depth is set on the drawing and held by the etch dwell time on each face. Stepped depth, where a shallow distribution channel feeds a deeper active channel, is produced with a second mask step, so the depth transition is defined by artwork rather than by tool wear.

How does etching compare with stamping for a flow field?
Stamping needs a die per layout and leaves a shear burr on the channel edge, while etching uses a phototool, keeps the channel edge open and lets the layout change without a die. Etching is also applied where the plate is too thin to form without distortion.

Can a plate carry a channel field on both faces?
Yes. Double-side etching is used where each face carries a channel field, and the base web between the two fields is defined on the drawing.

How are price and schedule handled for a custom plate?
Each plate is quoted from its own drawing: material, thickness, channel detail, quantity and the first article step all move the price and the schedule. Both are stated in the quotation and confirmed again after the first article is approved, since a custom plate changes with the requirements of each stack programme.

Send your plate drawing and our engineering team will review the channel field and reply with a quotation.