When an electronics plant orders cleanroom panels, the request almost always sounds the same: "panels like the ones pharma uses." Yet the two industries are hunting different enemies. Pharmaceutical cleanrooms chase sterility and particle control. Electronics cleanrooms chase particle control too, then add a threat that is completely invisible: static charge accumulating on wall surfaces, floors, and operator garments.
The difference is not a matter of taste. A panel that performs perfectly in a drug production room can fail outright in a PCB assembly bay, and the failure often surfaces months later in the end user's hands.
Sterility Is Not the Enemy Here, Static Charge Is
Electrostatic discharge (ESD) damage is rarely visible at inspection. IEC 61340-5-1:2024 sets the threshold for when a program applies: ESD control is required for components with withstand voltages from 100 V human body model (HBM) and 200 V charged device model (CDM) upward, while voltage on isolated conductors is capped below 35 V.
Compare that with everyday experience. The spark you feel touching a door handle already sits in the range of several kilovolts. In other words, the entire voltage band that destroys modern components lies far below what a human being can feel, hear, or see.
The consequence for the building is direct: every large surface inside the ESD Protected Area (EPA) — wall and ceiling panels included — must sit at the same potential and offer a controlled path for charge to bleed away. That is a materials specification and an installation detail, not a housekeeping task.
The Numbers That Decide It: 10^6 to 10^9 Ohms
This dissipative window is the core of panel selection for electronics. ANSI/ESD S20.20-2021 requires EPA flooring to measure below 1x10^9 ohms at all points. Dissipative materials sit between 1x10^6 and 1x10^9 ohms, while conductive materials fall between 2,5x10^4 and 1x10^6 ohms. Worksurfaces follow the same window, 1x10^6 to less than 1x10^9 ohms, for both point-to-point and resistance-to-ground.
The same standard binds the people too: the combined resistance of person, footwear, and floor must stay below 3,5x10^7 ohms. System-level figures like that matter because they show walls, floors, benches, and operators being treated as one circuit rather than as separate shopping-list items.
So why not make the panel as conductive as possible? Because below 10^6 ohms charge drains too quickly, and the resulting current spike is itself capable of destroying semiconductor junctions. Above 10^9 ohms, triboelectric charge builds faster than it can bleed off. Both roads end at latent defects: parts that pass factory testing and die in the field.
The test method belongs in the specification alongside the number. IEC 61340-2-3:2016 is the reference for measuring resistance and resistivity of solid materials across roughly 10 kilo-ohms to 1 tera-ohm, and it is the method relevant to panel surfaces. A certificate that says only "antistatic", with no test method number and no stated test humidity, proves nothing.
True ESD Facings versus Antistatic Sprays
Two products can both be called antistatic in a brochure while having wildly different service lives. The real difference is whether the dissipative property is built into the material or laid on top of it.
- Integral facing: a conductive carbon network or metallic particle matrix laminated into the panel skin during production. The dissipative behaviour is permanent and survives repeated cleaning.
- Topical coating: a hygroscopic solution that works by attracting water vapour. Effective temporarily, heavily dependent on room humidity, and worn away by cleanroom cleaning regimes.
- Post-cleaning data: ask for resistance results after dozens of cleaning cycles using the disinfectant that will actually be used, not just fresh-off-the-line panel data.
- Test humidity: surface resistance drops sharply in humid air. Data captured at 50% RH flatters a product destined for a room held at 35% RH.
- Colour proves nothing: a dark grey or black panel is not automatically dissipative, and a white panel is not automatically insulative.
Panel Grounding, the Step Most Often Skipped
A dissipative surface with no path to earth is simply a floating dissipative surface. Three things belong on the shop drawings: a grounding stud on every wall plane, bonding cables between panels because cam-lock joints and gaskets are not guaranteed conductive, and a tie-in to the same EPA bus bar that serves the floor and the benches.
The weak points appear in predictable places: door cut-outs, pass box frames, and cable penetrations. That is where the facing sheet is interrupted and electrical continuity disappears without anyone noticing. How to penetrate a panel without wrecking the core while preserving the grounding path is covered separately in our guide to electrical and plumbing work in sandwich panel walls.
Periodic verification is required by the program, not performed once at handover. IEC 61340-5-1:2024 calls for a program plan, a training plan, a product qualification plan, and a compliance verification plan, together with a named ESD program coordinator. Walls are among the items re-measured on schedule, and the records are kept.
ISO Class, Panel Core, and Room Humidity
Particle cleanliness is chosen separately from ESD control, even though both land on the same wall. SMT and PCB assembly generally runs at ISO Class 7, sometimes ISO Class 8 for packaging areas and component stores. Semiconductor wafer fabrication is far tighter, spanning ISO Class 1 to 5 depending on the process step. Per-class particle limits are detailed in our ISO 14644 cleanroom classification guide.
The panel core is chosen on thermal and fire grounds, not ESD grounds. Manufacturer datasheet ranges for thermal conductivity: EPS 0,033-0,038, PU or PIR 0,022-0,026, and rockwool 0,038-0,042 W/mK. For rooms holding high-value equipment and a serious fire load, rockwool remains the default choice, the same reasoning that governs modular data centre construction.
Humidity is the variable that links the two concerns. Industry guidance places 30-70% RH as the safe handling window, with 40-60% as the operational target. Many fabs deliberately run drier, at 30-50% RH, to prevent corrosion on wafers and metal surfaces, then cover the resulting static risk with ionisers rather than by raising humidity.
Primary references on both sides are openly catalogued: the ESD program document sits in the IEC 61340-5-1:2024 listing, while supporting technical material is published by the EOS/ESD Association.
FAQ
Can pharmaceutical cleanroom panels be used for electronics rooms?
They work for particle control, not for static control. Pharma panels are designed for cleanability and disinfectant resistance, and their surfaces are usually insulative. Without a dissipative facing and a grounding path, that wall becomes a place where charge accumulates. If the room handles sensitive components, the ESD specification must be requested up front, not patched in after installation.
What surface resistance is correct for electronics cleanroom panels?
The dissipative range of 1x10^6 to 1x10^9 ohms, in line with ANSI/ESD S20.20-2021. Below that the material is too conductive and risks current spikes; above it, charge has no time to bleed away. Ask for the figure to be evidenced by a test report using IEC 61340-2-3:2016, complete with the temperature and humidity at which testing was performed.
Is an ESD floor enough without ESD walls?
The floor is indeed the primary drain path because people stand on it, and the standard governs the person-footwear-floor combination below 3,5x10^7 ohms. But walls are large surfaces touched by trolleys, material carts, and operators' arms. In a low-humidity room, ignoring them leaves one uncontrolled charge source in place.
Can antistatic spray serve as a temporary solution?
As a short-term stopgap, yes. As a project specification, no. Topical coatings work by attracting water vapour, so performance collapses in dry rooms, and the layer wears off under routine cleaning. The cost of reapplication plus the risk of unprotected intervals usually exceeds the price gap of specifying integrally dissipative panels from the start.
