Executive answer
Four paths to name on the same drawing
- Draw the complete air route and the environmental boundary on the same assembly section. A channel between protected cavities is not automatically an opening to the outside.
- An edge vent can improve a key's air movement yet create an ingress route; a nominally sealed cavity can change key response. Treat these as two separate acceptance questions.
- Inspect the chosen route after lamination and installation, then validate key response and the specified exposure condition on a controlled mounted sample.
Current guidance context
What the buyer is really approving
A membrane-switch key moves a small enclosed volume of air as it is pressed. Epec describes inter-key tracks cut into a spacer; Snaptron lists several routes for metal-dome constructions. Neither source says that any particular drawing, including an HYR proposal, is sealed after assembly. The useful OEM question is not simply 'vented or sealed?' It is: from each cavity, where does displaced air go, and does that route cross the equipment's intended environmental boundary?
This is a drawing and first-article qualification guide, not an ingress-protection claim. It distinguishes an internal air-sharing route from a route open to ambient exposure, and it separates key feel from environmental protection. The supplier sources establish possible mechanisms; the route map and hold/revise/validate logic are editorial tools that must be filled with project evidence.
Name the protected boundary before choosing a vent
Start with the equipment section, not a key-only sketch. Mark the user-facing exposure side, the overlay perimeter, adhesive land, circuit tail exit, housing opening and any PCB or backer penetration. Highlight the line that is meant to separate exposure from protected components. A switch can move air among its own protected cavities without intentionally opening that line; a channel ending at an exposed outside edge is a different proposition. Whether the equipment interior itself is protected is a project fact, not an assumption.
Epec's design guide presents tracks between switches as a normal construction example. Its high-reliability keypad article separately explains why a spacer channel reaching a peripheral edge can become an external contamination path. Read the two statements together: 'venting' describes air movement, whereas 'sealing' describes which external route remains closed under the specified condition. Do not import Epec's general sealed-switch language as an HYR result or an equipment ingress rating.
Mark every intentional opening and every interface that must stay closed on the same controlled drawing. If a proposed channel leaves the switch but enters a supposedly protected housing volume, ask the equipment team to show how that volume is bounded and tested. If no one owns the boundary after the tail or PCB hole, the RFQ has an open engineering decision, not a pass.
Trace each cavity to its actual destination
For each key family, begin at the air volume beneath the moving feature. Follow the proposed route through the contact aperture and spacer geometry to the next cavity, shared internal space, PCB feature, top layer or edge. Show the direction as a connected path, not an isolated arrow labeled 'vent.' Then identify the destination's exposure classification: within the sealed stack, within a separately protected equipment space, or directly outside. A path can have branches; record every branch that could communicate with the cavity.
Snaptron describes three metal-dome examples: a route through the PCB, channels in a spacer, or a top vent in a dome array. These are alternatives tied to a particular dome and product construction, not interchangeable additions to every membrane switch. The same page warns that adhesive, overlay, spacer or PCB features in the final stack can accidentally block an intended route. Conversely, an unintended die-cut or exposed edge can connect a protected cavity to an unwanted environment. The drawing must therefore include the layer artwork and final assembly interfaces, not only the dome supplier's sketch.
Do not equate spacer stock thickness with a finished air channel. The channel exists only where the converted aperture and the laminated layers leave a connected opening. Ask for the controlled cut geometry, adhesive coverage, registration datum and layer orientation. A section through the key center alone can miss a blocked lateral channel or an exposed perimeter termination.
Use a path-to-boundary decision table
The table below is a drawing-review prompt, not a tested design library. Classify each proposed route by its final destination and by whether the project has evidence for that destination's protection. 'Internal' is meaningful only after all connected volumes and branch exits have been checked; 'inside the housing' is not automatically sealed. The OEM should name the required exposure and test method before accepting any path.
Keep two questions on separate rows of the design review: can the key actuate and recover as specified after mounting, and does the complete assembly meet its defined environmental boundary? A key that feels acceptable does not prove ingress protection. A part that survives one exposure condition does not establish the required key response across the rest of the equipment's life. This article offers no target force, IP class, test duration, cycle count or universal acceptance threshold.
If an air route is undefined, crosses a boundary without a qualified treatment, or disappears after mounting, hold the approval. The action may be to redraw the spacer, change which volume receives air, revise the enclosure interface or specify a different test sample. Choose only from project-compatible options after the supplier and equipment teams resolve the actual layer stack.
Inspect the finished stack, not a loose key
An unmounted dome sample can demonstrate a component response but not the airflow and tactile result inside the assembled panel. Snaptron explicitly notes that installed behavior can differ when the actuator, vent, spacer, PCB and adhesive change. Ask the converter for controlled layer drawings and, where the geometry can be seen, representative converted-layer inspection. Then inspect a laminated specimen and a production-intent mounted assembly, recording which route is visible or otherwise verified at each stage.
The equipment team should supply the real bezel, recess, backing, housing pressure, PCB and tail treatment. A housing rib, adhesive squeeze, extra liner left in the stack or assembly change could alter the intended path; these are review scenarios, not reported HYR failures. The inspection plan should say who checks the cavity openings, channel continuity and perimeter termination and by what non-destructive or sacrificial method. If a route cannot be observed directly, state the proxy measurement and what it does not prove.
Run the specified key-response check on the mounted configuration, including the affected key families and mounting conditions. Keep this separate from the OEM's environmental or ingress check on the complete equipment boundary. Link both results to the exact drawing and material revisions. A pass on one prototype does not authorize a different vent geometry, adhesive, housing or assembly process without an impact review.
Challenge five failure scenarios before sign-off
The following are hypothetical review traps, not HYR defects, customer cases or supplier test results. They are useful because a vent path can fail mechanically or environmentally even when one isolated drawing looks reasonable.
- A lateral spacer channel is drawn between keys but is closed by the next adhesive or printed layer. Ask for the registered layer stack and inspect the laminated specimen, not just the spacer artwork.
- A channel reaches the switch perimeter while the requirement calls for protection from washdown at that edge. Mark the edge as an exposure crossing and require a redesign or a defined equipment-level boundary and test.
- A vent hole through a PCB opens into a housing cavity assumed to be dry. Identify that cavity's actual exposure, openings and sealing owner; PCB routing alone does not qualify the equipment enclosure.
- One central key passes a loose-part feel check while a bezel or backing feature blocks air near an edge key. Sample each relevant key family in the mounted build and record the installation state.
- A sample passes one environmental check, then a new tail exit, adhesive pattern or housing revision changes the boundary. Treat the revision as a new interface decision and select checks to repeat.
Send one controlled RFQ and leave unknowns open
Provide the released key map, layer stack, vent-channel and circuit artwork, enclosure section, exposure direction, tail routing, intended assembly process and required key-response and environmental checks. Ask the switch supplier to annotate its proposed cavity-to-destination routes and identify all assumptions about the equipment boundary. Ask the equipment team to return the housing, PCB and tail interfaces it owns. A supplier cannot certify the final enclosure merely from an overlay drawing.
Specify the evidence package before prototype approval: revision-controlled layer and equipment drawings, a route/boundary map, converted and laminated observations, a production-intent mounted sample, measured key-response results under named conditions, separate environmental-test results and any deviations. Use project-specific criteria; none are supplied by this article. Record whether the disposition is accepted, accepted with a stated limit, or held pending a drawing or test change.
For an HYR inquiry, submit only the engineering files and open questions through the secure RFQ. Request a human project review of the actual construction and acceptance plan. The supplier sources, route table and parent-company photograph are not a promise of HYR vent geometry, IP rating, durability, schedule, price or completed product approval.