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SEMI F28-1103 © SEMI 1997, 2003 3 ( ≥ 0.02 µm) per cubic foot of test gas under test conditions. 6.2.3 Pressure Regulator — Pressure regulators are required to maintain system test pressures. 6.2.4 Pressure Gauge — Press…
SEMI F28-1103 © SEMI 1997, 2003 2
ISO 14644-2 — Cleanrooms and associated controlled
environments Part 2: Specifications for testing and
monitoring to prove continued compliance with ISO
14644-1.
NOTICE: Unless otherwise indicated, all documents
cited shall be the latest published versions.
5 Terminology
5.1 Abbreviations and Acronyms
5.1.1 CDA — Clean, dry air
5.1.2 EP — Electropolished
5.1.3 LPC — Laser particle counter
5.1.4 psi — Pounds per square inch
5.1.5 psia — Pounds per square inch absolute
5.1.6 psid — Pounds per square inch differential
5.1.7 psig — Pounds per square inch gauge
5.1.8 scfm — Standard cubic feet per minute
5.1.9 slpm — Standard liters per minute
5.1.10 SL — Standard liters
5.2 Definitions
5.2.1 background counts — counts contributed by the
test apparatus (including counter electrical noise) with a
spool piece in place of the test object.
5.2.2 Compressed Gas Association (CGA) — also
frequently used to refer to a fitting, as defined and
specified by the Compressed Gas Association, which is
used to connect a gas source cylinder to a panel inlet.
5.2.3 condensation nucleus counter (CNC) — a
discrete particle counting instrument that detects
particles, in a gaseous stream, by measuring light
scattered from droplets grown to measurable size by
condensation of supersaturated vapor upon the
particles.
5.2.4 dynamic test — a test performed to determine
particle contribution as a result of valve actuation or
regulator adjustment in a process panel during normal
operation.
5.2.5 process panels — a gas source control piping
system for delivering process gases as defined in SEMI
F13.
5.2.6 sample flow rate — the volumetric flow rate
drawn by the particle counter for particle detection.
5.2.7 sampling time — the time increment over which
counts are recorded.
5.2.8 source pressure — pressure of the source gas
applied to the cylinder connection at the panel inlet.
5.2.9 spool piece — a null component consisting of a
straight piece of electropolished tubing and appropriate
fittings used in place of the test component to establish
the baseline.
5.2.10 standard conditions — 101.3 kPa, 0.0°C (14.73
psia, 32°F).
5.2.11 static test — a test performed on an as-received
process panel with all valves in the fully-open position.
5.2.12 test duration — total time required to complete
the test procedure.
5.2.13 test flow rate — volumetric flow rate of the test
gas at standard conditions as defined in Section 5.2.10.
5.2.14 test pressure — pressure immediately
downstream of the test panel.
6 Test Procedure
6.1 Test Conditions
6.1.1 Precautions — This test method may involve
hazardous materials, operations, and equipment. This
test method does not purport to address the safety
considerations associated with its use. It is the
responsibility of the user to establish appropriate safety
and health practices and determine the applicability of
regulatory limitations before using this method.
6.1.1.1 Exhaust from the CNC may contain hazardous
and/or flammable vapors and should be properly treated
before being released to atmosphere.
6.1.2 The test is to be conducted at a normal indoor
temperature of between 18°C (64°F) and 26°C (78°F).
6.1.3 Test apparatus must be enclosed in a Class 100
environment (per ISO 14644). Use procedures
necessary to maintain Class 100 when handling test
apparatus and test components.
6.1.4 Care should be taken to protect the test apparatus
from excessive vibration. For example, vacuum pumps
and compressors should be isolated from the system.
6.2 Apparatus and Materials
6.2.1 Test Gas — Clean, dry nitrogen or air is to be
used [minimum dryness −60°C dew point at 790 kPa
(100 psig) and < 10 ppm total hydrocarbons]
6.2.2 Filters — Filters are required to provide
“particle-free” test gas. Each filter must be nine-log
retentive, per manufacturer’s specifications, to 0.02 µm
particles and have a pressure drop of less than 6.9 kPa
(1 psid) at the specified test pressure and flow rate. The
filter must be capable of achieving less than 1 particle
3
SEMI F28-1103 © SEMI 1997, 2003 3
(≥ 0.02 µm) per cubic foot of test gas under test
conditions.
6.2.3 Pressure Regulator — Pressure regulators are
required to maintain system test pressures.
6.2.4 Pressure Gauge — Pressure transducers or
gauges are required to monitor system test pressures.
6.2.5 Flow Control Device — A 0–100 slpm flow
control device is required for controlling the test flow
rate.
6.2.6 Tubing — A 6.35 mm O.D. × 0.89 mm wall (1/4"
O.D. × 0.035" wall) tubing is required. The tubing
shall have an average surface roughness of 0.25
micrometer (10 microinch) Ra or less. Electropolished
tubing (as defined in SEMI F16) is recommended.
6.2.7 Sampler — The sampling system consists of a
diffuser equipped with a pressure reducing device (e.g.,
critical orifice) and a sample probe. All parts of the
sampling system are to be electropolished with a
surface roughness of 0.25 micrometer (10 microinch)
Ra or less. If a critical orifice is to be used for pressure
reduction, it is not required to be electropolished. The
diffuser and sample probe must be sized to obtain
isokinetic sampling at the specified test conditions. The
critical orifice must be sized to obtain the specified
panel pressure at the specified test flow rate.
6.2.8 Spool Piece — Spool pieces shall be electro-
polished 316L stainless steel tubing with a surface
finish of 0.25 micrometer (10 microinch) Ra or better.
The spool piece is to be installed in the system in place
of the test device while obtaining background counts
for the system.
6.2.9 Fittings — Use face seal connectors or
compression fittings depending on test panel end
connections.
6.2.10 Gaskets — Use non-plated metal gaskets where
required.
6.2.11 A CNC capable of detecting particles at least as
small as 0.02 µm at a 50% efficiency envelope as
defined by ISO 14644, with a sampling flow rate of
1.23 SLPM (0.05 scfm) or greater, is to be used for
particle counting. A laser particle counter, capable of
detecting particles at least as small as 0.1 micro meters,
may be used in addition to, or in place of, the CNC.
Test durations in this test method have been established
based on a sampling flow rate of 1.23 SLPM (0.05
scfm).
6.2.11.1 Instruments should be calibrated regularly,
according to manufacturer’s recommendations. For the
CNC, this includes routine checks of sample flow rate,
working fluid level, and zero.
6.2.11.2 The CNC and data collection equipment
should have power surge suppression.
6.2.11.3 Setup and Schematic — See Figure 1.
SEMI F28-1103 © SEMI 1997, 2003 4
Figure 1
Panel Test Apparatus
6.2.11.4 The spool piece is to be installed when the test stand is not in use. A continuous low flow is to be
maintained to purge the system. The particle counter may be turned off. For an extended shutdown, the system
(excluding the CNC) should be pressurized and capped.
6.2.11.5 After initial construction, the spool piece should be installed and the system should be cleaned up by
running a high-flow rate of test gas (> 60 SLPM) and gently tapping all components (except the CNC) downstream
of the final filter. This procedure should be followed by a start-up phase which characterizes system cleanliness by
conducting the entire test protocol with the spool piece installed.
6.3 Test Procedures
NOTE 2: Ensure the counter is counting continuously and reporting data each minute. For the duration of the test, the counter
should be continuously counting, except where noted in the test protocol.
6.3.1 This test method classifies panels into three pressure ranges: high, medium, and low. The test pressures and
flow rates for each pressure classification are given in Table 1 below.
Table 1 Panel Test Conditions
Panel Pressure Class High Medium Low
Inlet Supply Pressure 3450 KPa (500 psig) 550 KPa (80 psig) 210 KPa (30 psig)
Panel Outlet Pressure 210 KPa (30 psig) 210 KPa (30 psig) 0 KPa (0 psig)
Test Flow Rate 60 slpm 60 slpm 5 slpm