General cleaning Guidelines
It is recommended you read the list of approved and banned materials first. For computers and associated equipment, please let the cleanroom manager know you plan to bring these items in and if you require LAN access from within the cleanroom. Before entering any part of the cleanroom, pre-clean the items with IPA and fibre free wipes. Detailed cleaning instructions will follow this general guideline.
For equipment such as computers, keyboards etc, vacuum clean using a general purpose vacuum cleaner. Particular attention should be paid to the ventilation ports.This pre clean should be done external to the cleanroom and anteroom and items should be covered with clean bagging material, but not of cleanroom quality. As a guide, notebook computers are preferred to desktop computers (although this is not always practical) not only due to size but also from a cleanliness aspect. Clean all equipment at an external location to the cleanroom. This equipment can then be bagged to minimise contamination.
Small metallic items (screws, nuts, washers) and non metallic items that are safe to use with solvents must be cleaned using the ultra sonic cleaner located in the chemical lab. Upon entering the cleanroom anteroom remove from packaging and visually inspect for any obvious signs of contamination that may have been missed and re-clean if necessary. The best way to visually inspect any item is to view the item surface at a five degree angle with good background lighting
When cleaning items using wipes provided in the anteroom do the following:
- Fold the wiper in half and then fold in half again.
- Now apply IPA to the folded wiper
- The maximum number of wiping actions per fold should be no more than four times.
- Wipe the surface in a single direction
- Once four wiping actions have been done, use the other folds to continue cleaning as above procedure.
If the person who performs the cleaning operation then goes into the cleanroom, a new pair of cleanroom gloves must be fitted. The clean item can then be taken into the cleanroom and any necessary final cleanup can be done within the cleanroom as described above using wipers and IPA provided. (see note 1 and note 2)
NOTE1: There are two sets of solvent carriers and solvent wash bottles in the cleanroom. The first set is located in the anteroom which is used for item cleanup and the other is located within the cleanroom. The second set located within the cleanroom is ONLY for use on optics and flight instruments/hardware. The solvent used in the second set is UVASOL and is spectroscopic grade propan-2-ol (IPA). Do not use this second set for general/surface cleaning. When using the spectroscopic grade IPA ensure that the nozzle of the wash bottles do not come into contact with the wiper or any other surface as cross contamination will occur if this happens
NOTE2: There are two grades of wipers used in the cleanroom. General purpose grade wipers (non woven polyester) are available in the Anteroom. These wipers should be used for item and general cleanup and should be recycled by disposing of them in the cleanroom laundry basket and NOT in the refuse bins. The second wiper is of a better quality (sealed edge non woven polyester with low particulate and extractable's). These wipers are available within the cleanroom in dispensers and should be used on flight quality instruments and hardware.
When bringing equipment into the cleanroom, ensure that you observe the following:
All cleanroom users should ensure that they consult the cleanroom manager before they bring any equipment and processes into the cleanroom.This cannot be stressed enough! The monitoring of equipment and processes going into the cleanroom is an important part of the general contamination control of the cleanroom. If bringing equipment or processes into the cleanroom ensure that you follow the detailed procedures listed below.
General tooling such as screwdrivers, nut drivers, rulers, vernier calipers etc. do not need to be bought into the cleanroom as there is a fully stocked cleanroom tool cabinet for all cleanroom users benefit. The tooling in the cabinet is for cleanroom use only and must never be removed from cleanroom. When using cleanroom tooling ensure that they are put back into the cabinet after use. Do not leave tooling lying about as this means that other users will not be able to use them. If you are a visitor and you need specialised tooling ensure that you contact the cleanroom manager to confirm whether the tooling is available.
If you are bringing a process into the cleanroom ensure you have done a risk assessment on the process and you have discussed this with the cleanroom manager. Under no circumstances may any process go into the cleanroom unless it has been discussed with the cleanroom manager, again this is a monitoring activity to aid in cleanroom contamination control and for Health and Safety reasons.
IntroductionIn order to meet project contamination cleanliness requirements, ground support equipment (GSE) used in clean areas at MSSL for flight hardware integration and testing needs to be cleaned at regular intervals. This is to ensure that surface contamination levels are minimised and the possibility of contamination redistribution from the GSE to the flight hardware is significantly reduced.Required equipment
- Isopropyl Alcohol (IPA): Analar grade for course and intermediate cleaning and spectro grade for precision cleaning.
- Cleanroom Wipes: Lint-free Polyester
- Vacuum Cleaner: HEPA-filtered for precision cleaning
- Acetone: Analar grade for course and intermediate cleaning and spectro grade for precision cleaning
- Cleanroom Swabs: Woven Polyester
- Compressed Air or Nitrogen, filtered for particles to 0.5 micron
- White light source (100W)Before use in a controlled clean area, GSE must be cleaned and inspected for visible cleanliness. GSE cleaning should be performed to visibly clean � sensitive level (VC-S) as defined in MSSL/PA/PS/Q012 �Procedure for verifying surfaces to a visibly clean level�. To achieve this surface cleanliness standard, GSE cleaning should be performed in three stages as defined below:
Course cleaning can be performed in non clean areas (workshop, office etc). The idea is to remove the bulk of contaminants from the hardware. Nitrile gloves should be worn during course cleaning
Intermediate cleaning should be performed in the anteroom. Particular attention should be paid to surfaces, crevices, corners, vents etc and these should be cleaned using appropriate solvents or detergents. A more thorough inspection of all surfaces is required at this stage. Cleanroom wipes and nitrile gloves should be worn while performing intermediate cleaning.
Precision cleaning should be performed inside the cleanroom but away from flight hardware (ideally at entrance to cleanroom). Spectro grade solvents should be used and polyester cleanroom wipes. Cleanroom dress code of mask, hood, cleanroom bunny suit, overshoes and nitrile gloves should be observed. A methodical and thorough surface inspection should be carried out as defined in MSSL/PA/PS/Q012 �Procedure for verifying surfaces to a visibly clean level� to a VC-S level after cleaning.Cleaning procedures
- Determine the surface sensitivity to handling and solvents. If the surface is sensitive to IPA or acetone, use filtered critical neutral detergent. If the surface is sensitive to handling, limit or eliminate vacuum use and handling as necessary to prevent GSE damage.
- If computing equipment is to be brought into clean areas laptop devices are preferred. If this is not possible desktop computers should be thoroughly cleaned inside and outside the casing paying particular attention to exhaust fans from the power supply.
- Computer monitors should be thoroughly vacuumed paying particular attention to the monitor vents prior to cleaning procedure below.
- Computer keyboards should be turned upside down and a jet of clean filtered compressed air or nitrogen directed between the keys prior to cleaning procedure listed below.
- Remove loose particles from the GSE by thoroughly vacuuming all surfaces, including holes, crevices, and corners, with a vacuum cleaner. This step should not be performed for items sensitive to handling. Minimise direct nozzle contact with GSE surfaces and continue until no particles are visible on GSE surfaces.
- Lightly dampen a cleanroom wipe with IPA (Analar grade or equivalent). Do not saturate the wipe or dip the wipe in the solvent container.
- Clean the GSE surface with the IPA dampened wipe, wiping the surfaces in a unidirectional manner. Do not overlook crevices, corners, or holes. If necessary, lightly dampen a swab with IPA and use the swab to clean recessed areas. Clean recessed surfaces with the swab by rotating the swab over the surface. During cleaning, fold the wipe to expose a clean surface or replace with a new wipe if the wiping surfaces become contaminated. Replace swabs when visibly contaminated. Lightly dampen each new wipe surface or swab with IPA and continue cleaning. Repeat until GSE surfaces do not display visible contamination.
- If solvent remains on any GSE surfaces, particularly blind holes or other recesses, dry the surfaces completely with filtered, oil-free GN 2 or air. Regulate the gas flow as necessary to prevent solvent splashing and damage to GSE surfaces. After solvent wiping, inspect surfaces for visible cleanliness as defined in MSSL/PA/PS/Q012.01 �Procedure for Verifying Surfaces to a Visibly Clean Level�
- If visual inspection reveals surface contaminants, repeat the solvent wiping procedure above and re-inspect. If contamination still remains visible after solvent wiping, repeat the solvent wiping procedure with acetone substituted for IPA. Before using acetone, however, verify that it will not degrade the materials undergoing cleaning. If contaminants remain visible after using acetone, contact the contamination control manager (CCM).
- Lightly dampen a cleanroom wipe with spectro grade IPA. Do not saturate the wipe or dip the wipe in the solvent container.
- Clean the GSE surface with the spectro grade IPA dampened wipe, wiping the surfaces in a unidirectional manner. Do not overlook crevices, corners, or holes. If necessary, lightly dampen a swab with IPA and use the swab to clean recessed areas. Clean recessed surfaces with the swab by rotating the swab over the surface. During cleaning, fold the wipe to expose a clean surface or replace with a new wipe if the wiping surfaces become contaminated. Replace swabs when visibly contaminated. Lightly dampen each new wipe surface or swab with IPA and continue cleaning.
- If solvent remains on any GSE surfaces, particularly blind holes or other recesses, dry the surfaces completely with filtered, oil-free GN 2 or air. Regulate the gas flow as necessary to prevent solvent splashing and damage to GSE surfaces.
- After solvent wiping, inspect surfaces for visible cleanliness as defined in MSSL/PA/PS/Q012 �Procedure for Verifying Surfaces to a Visibly Clean Level�. The surface cleanliness level should be VC-S. A white light source (100W) can be used to aid inspection. Repeat above cleaning procedure until GSE surfaces do not display visible contamination.
- All cleaned GSE cables can then be sleeved in Llumalloy bagging. Sleeve ends should be sealed with clean cable ties or Kapton tape.
Note: Depending on project contamination control requirements certain GSE may require cleaning to a more stringent level such as VC-HS. The above procedure can be adapted to suit this requirement by substituting the appropriate inspection procedure as defined in MSSL/PA/PS/Q012. Cleaning methods will remain the same.