Cleanroom Requirements During SCT
Assembly
As we move into handling opto-harnesses -- which are extremely vulnerable
to damage by small sparks (ElectroStatic Discharge) and dirt blocking the
optical connections -- and start exposing modules for long periods
during module mounting and disc-to-cylinder mounting, we need to be very
careful to work cleanly and with ESD safety. Here are guidelines for
maximising our protection in H023, H025, H026 and the muon clean-room.
Order of dressing
Dress from top to bottom so that any dirt that falls
ends up under protective clothing. Do this before entering the cleanroom
or going through the curtains.
Hats
Wear a blue hat.
Coats
Wear a blue coat with both horizontal and vertical
dark threads. These are static safe. The ones with only vertical threads
are not ESD safe and should be removed from our cleanrooms.
Keep to your own coat. Visitors coats are available in the two lockers outside
H025.
Shoes
Wear either ESD safe shoes or ESD safe over-shoes.
The original set of shoes bought in 2004 are anti-static, but not ESD safe.
They are difficult to charge up (anti-static) however they insulate you from
the floor so do not allow you to discharge any potential you pick up. New
shoes have been bought which are ESD safe; they conduct charge away from
you to the floor, via a high resistive path.
The blue and white overshoes are not ESD safe and are forbidden: better to
walk in your socks or dirty shoes than wear these. Only the new white ones
with the black strap are ESD safe.
The black strap is attached for part of its length to the white overshoe.
This part of the black strap must be on the outside, directly against the
floor. The free end must go over the side of your shoe and inside, into the
heel area, pushed under your heel.
Check that you are ESD-safe in the bonding room (H027), just behind the entrance
door. With your cleanroom shoes or over-shoes on, stand on the plate, put
the switch into "Shoes" position, and push the button. Do this check at least
weekly.
We have ordered more test equipment to make this more convenient.
Step on the white sticky mat to make sure your cleanroom (over-)shoes are
clean. The white mats are not for cleaning your normal shoes
on.
Masks
When working near modules, wear a mouth mask to prevent
saliva ending up on the module.
Wrist-straps
Owing to the risk of the lead of a wrist strap colliding
with a module, the basic recommendation is don't wear them when modules are
around. If you need to wear one, make sure you have it the correct way round
against your skin. Test it in H027.
When not wearing a wrist strap, always discharge yourself first by touching
the table or tooling you are about to work at, before touching anything on
a disc.
Gloves
If you need to wear gloves, e.g. when handling copper
grounding and shielding planes, consider whether you need ESD-safe ones.
Nigel Hessey6 March 2005