Hermetically Sealed vs IP Rated Switches
A hermetically sealed switch and an IP rated switch are not two grades of the same thing. Hermetically sealed describes how the part is built. An IP rating describes what happened when the part was put through a defined test. Swiclick is a switch manufacturer whose sealed products are specified with IP ratings rather than hermetic seal claims, and knowing which of the two your application actually needs decides whether a supplier list is long or very short.
What Hermetically Sealed Means
In its strict engineering sense, hermetic sealing means a gas-tight enclosure, normally achieved by fusing metal or glass rather than by compressing an elastomer.
A true hermetic switch has its contacts inside a welded or glass-to-metal sealed envelope, often with an inert gas fill. A properly specified hermetic enclosure limits gas and water vapour transmission to a verified leak-rate threshold, typically measured with helium or another tracer gas and expressed in standard cubic centimetres per second. It is a verified threshold rather than mathematically zero leakage.
That construction is used in aerospace, military and hazardous-area equipment. It is expensive, it constrains the mechanism, and the supplier list is short.
The word is also used loosely. A moulded rubber boot over an actuator is often described as a hermetic seal in marketing copy, and it is not one. An elastomer seal is a barrier with a permeation rate, not a gas-tight envelope. If a supplier calls a boot-sealed switch hermetic, ask for the leak rate and the test method.
What an IP Rating Actually Says
An IP rating is a test result under IEC 60529, expressed as two digits.
The first digit covers solid ingress up to dust-tight. The second covers water, from dripping through spray and jets to immersion. The difference between the immersion levels is a separate subject, covered in the piece on IP67 and IP68.
Three properties of the system matter here.
It is a pass or fail against defined conditions, not a measure of how much better than the threshold a part is. It is tested on a specific construction, so changing a seal material means retesting. And it is not cumulative, so a part tested for immersion has not necessarily passed the jet tests.
An IP rating tells you a part survived a defined water and dust test. It does not tell you the enclosure is gas-tight, and it says nothing about vapour transmission over years.
The Practical Difference
Put the two side by side on the properties that decide a design.
| Hermetically sealed | IP rated | |
| What it describes | A construction | A test result |
| Typical barrier | Welded metal or glass-to-metal seal | Elastomer boot, gasket or laminated film |
| Verified by | Leak rate measurement | Pass or fail against IEC 60529 conditions |
| Long-term vapour transmission | Very low where the verified leak rate meets the requirement | Not the property being tested |
| Supplier availability | Narrow | Wide |
| Relative cost | High | Moderate |
Decision rule: specify hermetic sealing when long-term gas or vapour exclusion is the requirement, or when a standard for your application demands it. Specify an IP rating when the requirement is surviving dust, splashing, wash-down or temporary immersion.
The Failure Neither Rating Covers
Some sealed-switch failures in service come from conditions that a one-time immersion test does not reproduce.
A sealed cavity behind a boot contains air. Heat the product and that air expands against the seal. Cool it and the cavity draws a partial vacuum. If condensate is sitting on the seal face at that moment, the switch can draw it in. Repeat that daily for a year and moisture accumulates inside a part that passed its immersion test on day one.
Neither an IP rating nor a hermetic classification demonstrates resistance to repeated thermal and pressure cycling on its own. A verified hermetic construction generally offers much lower vapour permeation than an elastomer seal, but thermal cycling resistance still has to be demonstrated for the finished construction, because welded and glass-to-metal joints have their own expansion mismatch and fatigue behaviour.
Chemical attack is the other gap. Boot materials are usually silicone or a thermoplastic elastomer, and neither resists every solvent. This is the same reason washing a tactile switch after reflow needs its own check rather than an inference from the IP number.
If your product runs hot and cools somewhere damp, ask for thermal cycling data with a humidity component. That is a more useful question than asking for a higher IP digit.
What to Ask a Supplier
Five questions separate a real specification from a word on a web page.
- Is this a hermetic seal with a measured leak rate, or an elastomer seal with an IP rating? Ask for the leak rate and test method if the answer is hermetic
- Was the IP rating tested on the bare component or on an assembly?
- Is there spray or jet data as well as immersion, if the product gets washed down?
- What is the seal material, and has it been checked against our cleaning chemicals?
- Is there thermal cycling data with a humidity component?
Swiclick specifies sealed products with IP ratings rather than hermetic seal claims. Sealed tact switch families are listed under IP67 waterproof tact switches, and sealing options across the micro switch range vary by part number, so confirm the exact model and its supporting test evidence before writing it into a specification. The full test detail for the IP system sits in ANSI/IEC 60529, which is published free.
FAQ
For long-term exclusion of gas and water vapour, yes, because that is what the construction is for. For surviving dust, splashing or temporary immersion, an IP rated switch is usually the appropriate and far more available answer.
Yes. The two describe different things, so a hermetic part can also be tested and rated under IEC 60529.
No. An elastomer barrier has a permeation rate. Hermetic sealing in the strict sense means a gas-tight envelope, normally welded metal or glass-to-metal, verified by a leak rate measurement.
By measuring the leak rate, commonly with a tracer gas such as helium, and expressing it in standard cubic centimetres per second. Ask for both the figure and the method.
Common gaps include repeated thermal and pressure cycling, condensation inside a sealed cavity, chemical attack on the seal material, and long-term vapour transmission.
Sealed products in the current range are specified with IP ratings rather than hermetic seal claims. If your application requires a verified leak rate, say so at enquiry so we can tell you whether it is something we can do rather than after a sample.
Talk to an engineer
Tell us your application and the specs you need, and our engineers will match a Swiclick switch and share its datasheet and pinout. Free samples ship 1 to 50 for validation before volume.
Written by Eric Chen, Application Engineer, Swiclick.
