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Ultraclean CCD project

Outgassing of CCD components in the vacuum
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Characterized probes

Before we started with the measurements, all probes were high-grade cleaned with alcohol or acetone and baked in the vacuum oven for several days. Painted shields, however, were just baked. After this procedure we handled the components with clean room gloves only.

As air pollution will infiltrate the probe chamber during the insertion of a probe and because some impurities condensed on the sensor of the mass spectrometer when it was out of use overnight, we had to wait some time after the start of the vacuum pump and the mass spectrometer before beginning with a scan. Approximately 45 minutes proved to be a good time in which all contaminations not originating from the probe were pumped away. If the residual gas analyzer has been in use for another measurement just before and only the probes were exchanged, this time was reduced to 20 - 30 minutes.

In the following, we distinguish probes with zero, poor and rich emission. Great efforts were made to assign each line to the evaporating element and numerous atomic libraries were used. Unfortunately, it was not possible to identify all lines.

Components without significant outgassing Components with slight outgassing Components with strong outgassing
Coax video cables Heating element Vacuum connector
Fiberglass
(HGW 2372, Ferrozell)		 Small black internal connectors
(Harwin Data Mate)		 VITON™ O-ring
Raw boards Broad connector
(MCKAL-P-37PX1369)		 Painted shields
ZIF-sockets Parylene coating Dark vacuum grease
(FM 090, Balzers)
High density connector
(MCK-AL-L-37S)		 White vacuum grease
(Tyreno Fluid, Vacugrease F-V2)
White self-repairing over-temperature fuse Finger grease
Brown over-temperature fuse Glue
(Master Bond EP21TCHT-1)
Heating power resistor
(75 ohms, Caddock, MP930, TO-220)		 Contaminated CCD
Vacuum valve
Starflex raw board
Orange Kapton foil
Black ceramic KEPLA COAT™

Summary of critical contamination lines

Only those lines [amu] (amu = atomic mass unit) which also appear on the contaminated CCD are shown here. Lines which occur only occasionally are shown in brackets.

Line [amu] 50 51 53 55 56 57 67 69 71 73
Heating element           x       (x)
Harwin Data Mate       x x          
Broad connector       x x          
Vacuum connector x             x    
VITON™ O-ring       x x x x x x  
Painted shields     x     x   x    
Vacuum grease (Balzers) x             x    
Vacuum grease (Tyreno)               x    
Finger grease x x x x x x x x   x
Glue (Master Bond) x x x x x x x x x x
Contaminated CCD x x x x x x x x x x

Last update: Feb 10, 2010