9018-18076.pdf.pdf - 第31页
Environmental Requirements 5 Site Preparation 5-3 Air Temperature Requirements Ta b l e 5 - 7 summarizes the temperature and cooling requ irements for the system. F or details, see: • Air Temperatur e Specifi cations • C…
5-2 Site Preparation
5 Environmental Requirements
Air Quality Requirements
As a rule, good air quality is as important for the reliability of your Medalist ICT system as it is for your
production process. Three types of airborne contaminants are discussed below. The presence of any
of these contaminants at the site will contribute to system degradation, resulting in lower reliability
and higher operating costs.
Corrosive Contaminants
Corrosion is a complex form of material deterioration or destruction by chemical or electrochemical
reaction. The presence of corrosive contaminants (gases) in the atmosphere is very common in
industrial environments. If ignored, corrosion can eventually degrade system performance by its
effects on high impedance circuits and low impedance interfaces. It can also deteriorate most plastics
including software storage media. The effects of corrosive contaminants are usually accelerated at
high humidities or high temperatures.
Corrosives generally cannot be filtered out of the air by normal filtration methods, and the techniques
that must be used for their removal are complex and costly. If the source of corrosive contaminants
cannot be eliminated, the system should be installed in an enclosed environment with a fresh air
supply at positive pressure.
Particulate Contaminants
Particulate contaminants (hard particles) consist of smoke, dust, hair, lint, fibers and miscellaneous
organic and inorganic materials. The presence of these contaminants in the air can cause system
degradation, especially where disk drives, test fixtures, and low impedance interfaces are concerned.
Particulate contaminants can be filtered from the air, and appropriate filters should be included with
any air conditioning installation. Also consider installing “No Smoking” signs in the area. Tobacco
smoke is a well-known factor in fixture contact contamination. It causes false failures leading to
unnecessary DUT repairs and higher production costs.
Viscid Contaminants
Viscid contaminants are oily or sticky airborne substances that can be deposited on the system’s
electronic and mechanical parts. Besides contributing directly to system degradation, viscid
contaminants collect and hold particulate contaminants and make cleaning very difficult. Viscid
contaminants can be removed from the air by filtration, but the elimination of their source, if possible,
is preferable.
Environmental Requirements 5
Site Preparation 5-3
Air Temperature Requirements
Table 5-7 summarizes the temperature and cooling requirements for the system. For details, see:
• Air Temperature Specifications
• Cooling Requirements
Air Temperature Specifications
The Medalist ICT system is designed to operate uninterrupted in an area where the air temperature is
stable and in the range from 0°C to 40°C (32°F to 104°F), as measured at the tester-to-fixture
interface.
The system has a built-in temperature sensor inside the testhead, located on the ASRU card. This
sensor constantly monitors the temperature of the air that has been drawn through the testhead after
it cools the system components. If the temperature sensor finds that the air temperature inside the
testhead has changed ±5°C (±9°F) since the last time the system ran AutoAdjust All, it will run
AutoAdjust All again. Therefore, to ensure uninterrupted use, it is important that the ambient room
temperature remain reasonably stable.
If the sensor finds that the air temperature inside the system is too high, the system will shut down;
typically, the over-temperature shutdown point is 55°C (131°F). See Cooling Requirements for
information on air conditioning requirements.
Cooling Requirements
Design the site cooling capability using the heat dissipation estimates in Table 5-8. The numbers are
for testheads with fully loaded modules and fully loaded support bays.
Table 5-7 Temperature and humidity ranges for operation and storage
Operating Temperature Operating Humidity Storage Temperature
Testhead 0°C to 40°C (32°F to 104°F) 5% to 80% non-condensing -40°C to 70°C (-40°F to 158°F)
Support Bay 0°C to 40°C (32°F to 104°F) 5% to 80% non-condensing -40°C to 70°C (-40°F to 158°F)
Controller 5°C to 45°C (41°F to 113°F) 20% to 80% non-condensing -40°C to 65°C (-40°F to 149°F)
The air temperature inside the system is not considered stable until the system has
been powered for at least 30 minutes.
Table 5-8 System heat dissipation
Number of Modules Dissipation
1 module 10500 BTU (3.1 kW)
2 modules 19700 BTU (5.8 kW)
3 modules 28500 BTU (8.4 kW)
4 modules 3700 BTU (10.9 kW)
5-4 Site Preparation
5 Environmental Requirements
Humidity Requirements
The system is designed to operate in the range from 5% to 80% relative humidity (non-condensing).
If the system is subjected to condensation, as if moved from a cold loading dock into a warm
environment, allow at least 24 hours for the system to recover before powering up.