The filters in a nanofabrication cleanroom are the most reliable part of it. The gowning sequence, the garments, the traffic and the enforcement are where the class is lost, and where a facility with no manager can still hold the line.
Operational particle measurements can reveal contamination introduced during gowning, entry and normal work. Compare these with at-rest measurements and maintenance records before deciding whether the cause is people, airflow, equipment or cleaning.
Personnel can be a significant particle source, but filters, seals, airflow balance and process equipment also need verification. A gowning procedure complements engineering controls; it cannot compensate for a failed filter or pressure-control system.
Separate gowning issues from engineering faults
A classification report should state the occupancy condition and test arrangements. ISO 14644-1 classifies airborne particle concentration; the operational condition should reflect the people and processes the facility is intended to support. Do not treat an at-rest result as proof of cleanliness during use.
People, equipment and processing all contribute to operational counts. Compare occupancy and movement with fixed-point measurements, then address the sources shown by the data. Reducing unnecessary traffic may help, but it does not replace adequate air handling or process containment.
Occupancy is a specification. Decide the maximum number of people the room supports and enforce it through the booking system, not through goodwill.
Traffic is a source. Every entry and exit disturbs the pressure cascade. Batching work into fewer, longer sessions is cleaner than many short ones.
What people actually bring in
The gowning protocol exists to intercept a specific list, and it helps to name it. Staff who understand what they are stopping follow the rule better than staff who are only told to follow it.
Skin and hair. The largest single source, and continuous.
Cosmetics and personal products. Powder makeup, hairspray, aerosol deodorant and heavily scented lotion all release particles, and amine-containing products contaminate chemically amplified resist in a way that shows up as unexplained lithography failure days later.
Paper and cardboard. Ordinary notebooks, printed protocols and cardboard boxes shed cellulose fibre in quantity. Only cleanroom paper and non-shedding pens cross the line, and boxes are unpacked in an anteroom.
Phones and laptops. Warm, fan-cooled and carrying a day of Dhaka street dust. Either they are wiped down with lint-free wipes and isopropanol at the boundary or they stay outside.
Wet clothing and umbrellas. During the monsoon the gowning room becomes a drying room. Water on the floor lifts particles as it dries and it kills the tacky mat.
Shoes. Site dust from a campus with construction on it, which describes most Bangladeshi campuses, is why a shoe cleaner and a step-over bench earn their floor space.
The gowning sequence, and why the order matters
Gowning runs from the top down and from the outside in, so that anything dislodged from an upper garment lands on a surface that is still going to be covered. Print this and put it on the wall.
Remove outdoor shoes and outerwear in the pre-gowning area. Bags, food and drink stay outside the boundary.
Wash hands and dry them fully. Damp hands contaminate the inside of gloves and make a coverall stick as you step into it.
Fit shoe covers or dedicated cleanroom shoes while sitting on the crossover bench, moving one foot at a time to the clean side. The bench is the line between dirty and clean, and once a foot has crossed it, it does not go back.
Fit the hair cover, then a beard cover if required, then the face mask. All hair goes inside the cover, fringe included.
Put on the hood, tucking the shoulder cape flat so that it will sit under the coverall collar.
Step into the coverall without letting it touch the floor. This is the most commonly broken rule in any facility. Support the legs of the garment as you step in.
Fit cleanroom boots over the shoe covers, with the coverall leg inside the boot.
Fit safety glasses or goggles.
Put on gloves last, pulling the cuff over the coverall sleeve so that no skin is exposed at the wrist.
Check yourself in a full-length mirror before entering the air shower. If there is no mirror, install one.
Degowning has an order too, and it is not simply the reverse. Gloves and the outer layer come off first so that clean hands remove the hood and mask, and each garment goes to its labelled hook or the disposal bin rather than a heap on the bench.
Choosing garments, and the laundry question
The garment decision usually comes down to whether reusable suits can be laundered to a cleanroom standard within reach of your site.
Disposable garments need no laundry chain and suit a facility with irregular use. The cost is per entry, which makes a teaching cleanroom with large student groups expensive, and the waste has to leave the building.
Reusable polyester garments with a carbon grid last many cycles and cost less per entry at high utilisation. They only work if there is a validated cleanroom laundry you can actually use. Washing them in an ordinary machine puts lint back onto the fabric and defeats the purchase.
Static control requirements follow the process and hazard assessment, including device sensitivity and any flammable materials. A garment without a conductive grid holds charge, attracts particles and can discharge into a device.
Fit is a technical requirement. A coverall that is too large sweeps the floor and a hood that is too small rides up and exposes hair. Buy a size range, not an average.
If disposables are the answer, specify a bound seam rather than a serged one. A serged seam sheds along its entire length.
The gowning room itself
A badly laid out gowning room guarantees a broken protocol no matter how well the protocol is written.
A physical dirty-to-clean progression with the crossover bench dividing the room. If people can walk in a straight line from corridor to cleanroom door without the bench forcing a change of state, they will.
Enough hooks and cubbies for maximum occupancy. When there are six hooks and eight users, two garments end up on a bench.
Tacky mats on a peel schedule. Peel a layer on a fixed schedule and write the date on the exposed layer. A mat peeled only when somebody notices it is dirty is a source, not a sink.
Positive pressure relative to the corridor, with a differential pressure gauge that somebody reads and logs daily. A gauge nobody reads is decoration.
An air shower used properly. The interlock only helps if people wait for the cycle. If the cycle is long enough to be annoying, the shower quietly becomes an expensive corridor.
Enforcement without a cleanroom manager
A facility needs a named person responsible for access, procedures and records, even where a full-time cleanroom manager is not funded. Assign duties and cover during absence rather than rely on informal oversight.
Access control tied to induction. Card access is granted after a gowning induction and a witnessed practical, and withdrawn on a documented breach. This is the most effective control available to a facility with no manager, because it requires nobody to be present.
A named owner per session rather than a manager for the facility. Whoever books the slot is responsible for everyone who enters on that booking, visitors included.
Wall instructions in Bangla and English, with photographs of each step rather than paragraphs of text. Photographs of your own staff in your own gowning room work better than a manufacturer's poster.
A buddy check at the mirror. Two people entering together check each other. It takes seconds and it catches exposed hair and unsealed cuffs, the two failures that matter most.
Visitors gowned by a host, never self-gowned. A delegation walking through in shoe covers and a lab coat is the most expensive tour a facility can give.
A short breach log. Date, what happened, action taken. It exists to show a pattern, not to punish anybody.
What to monitor, and how often
Monitoring turns a protocol from a belief into a measurement, and it does not need to be elaborate.
Differential pressure across each boundary, logged daily by whoever opens the facility.
Particle counts at fixed points, operational and at rest, on a fixed interval and at the same locations every time so that the numbers are comparable.
Filter integrity and airflow on the schedule in the maintenance contract, with results filed where the next engineer can find them.
Consumable stock. Running out of gloves or shoe covers on a Thursday afternoon is how a protocol gets suspended, and a suspended protocol rarely resumes cleanly.
Then correlate the log against process results. When a lithography batch fails, the first question should be what the room was doing that week, and that question is only answerable if somebody has been writing the numbers down.
Vvon can help discuss environmental-monitoring and nanofabrication equipment requirements. Gowning procedures, cleanroom certification and ventilation design remain the responsibility of appropriately qualified facility teams. Send the proposed class, occupancy and process list to info@vvon.com.bd or call +8801805987890 to define the equipment scope.