System-Board Connectors - Lenovo ThinkEdge SE350 V2 Hardware Maintenance Manual

Table 7. Limits for particulates and gases
Contaminant Limits
Reactive gases Severity level G1 as per ANSI/ISA 71.04-1985
• The copper reactivity level shall be less than 200 Angstroms per month (Å/month ≈ 0.0035 μg/
cm
• The silver reactivity level shall be less than 200 Angstroms per month (Å/month ≈ 0.0035 μg/
cm
• The reactive monitoring of gaseous corrosivity must be conducted approximately 5 cm (2 in.) in
front of the rack on the air inlet side at one-quarter and three-quarter frame height off the floor
or where the air velocity is much higher.
Airborne Data centers must meet the cleanliness level of ISO 14644-1 class 8.
particulates
For data centers without airside economizer, the ISO 14644-1 class 8 cleanliness might be met by
choosing one of the following filtration methods:
• The room air might be continuously filtered with MERV 8 filters.
• Air entering a data center might be filtered with MERV 11 or preferably MERV 13 filters.
For data centers with airside economizers, the choice of filters to achieve ISO class 8 cleanliness
depends on the specific conditions present at that data center.
• The deliquescent relative humidity of the particulate contamination should be more than 60%
RH.
• Data centers must be free of zinc whiskers.
1 ANSI/ISA-71.04-1985. Environmental conditions for process measurement and control systems: Airborne
contaminants. Instrument Society of America, Research Triangle Park, North Carolina, U.S.A.
2 The derivation of the equivalence between the rate of copper corrosion growth in the thickness of the corrosion
product in Å/month and the rate of weight gain assumes that Cu
3 The derivation of the equivalence between the rate of silver corrosion growth in the thickness of the corrosion
product in Å/month and the rate of weight gain assumes that Ag
4 The deliquescent relative humidity of particulate contamination is the relative humidity at which the dust absorbs
enough water to become wet and promote ionic conduction.
5 Surface debris is randomly collected from 10 areas of the data center on a 1.5 cm diameter disk of sticky
electrically conductive tape on a metal stub. If examination of the sticky tape in a scanning electron microscope
reveals no zinc whiskers, the data center is considered free of zinc whiskers.

System-board connectors

The following illustration shows the internal connectors on the system board.
ThinkEdge SE350 V2 Hardware Maintenance Guide
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2 -hour weight gain). 2
2 -hour weight gain). 3
4
1 :
5
S and Cu O grow in equal proportions.
2 2
S is the only corrosion product.
2