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SEMI F27-0997 © SEMI 1997, 2003 4 7.1.1 Initial Dry Down — Start the experiment with the blank in place of the test specimen and a flo w of dry gas through th e APIMS. The APIMS output should be at equilibrium with the l…

SEMI F27-0997 © SEMI 1997, 2003 3

6.4 Moisture Pulse Generator — A valving arrangement capable of switching rapidly between dry and humidified

nitrogen is also required. An example of such a design is shown in Figure 1. In this design, flow is maintained in

both the humidified and dry gas lines at all times. By simultaneously switching valves V

and V

, or V

and V

either humidified or dry gas is directed through the test specimen while the other gas stream is directed to vent. Note

that there is a bypass loop so that flow can be maintained to the APIMS when the specimen is removed. In this

design, all gas lines, but especially those lines between V

and V

and between V

and V

, should be as short as

possible and constructed of EPSS tubing of high quality. Maintaining gas lines at a constant temperature between 50

and 80°C wherever possible is also recommended.

Figure 1

Moisture Test Schematic

6.4.1 The bypass loop will contain a stagnant volume of gas during testing. To avoid exposing the APIMS to a large

moisture upset whenever it is fed the gas contained in the bypass loop, the loop should be thoroughly baked out (at ≥

200°C) and protected from atmospheric contamination thereafter. Valve V

should be such that some flow can be

maintained through the bypass loop and the test specimen simultaneously as well as through each separately. Use of

pneumatic valves to facilitate rapid and simultaneous switching is recommended.

6.4.2 Other arrangements than that shown may also be used. The moisture pulse generator should be designed so as

to give the fastest possible response of the blank to a change in input moisture level.

6.4.3 Use of a glove box or other such enclosure about the test specimen and adjacent piping, to minimize exposure

of the system to ambient contamination when removing and introducing the test specimen, will improve the

precision of moisture content measurements but not of moisture interaction measurements. Use of such an enclosure

is, therefore, left to the discretion of the operator.

6.5 Temperature Control and Measurement — A stable temperature during the test is of critical importance. The

test component shall be kept at 35°C. TESTS AT DIFFERENT TEMPERATURES CANNOT BE

COMPARED. Ideally, the blank and device under test should be maintained in a temperature-controlled chamber.

However, if this is impractical, heating tape can be used. Temperature shall be measured at 1 m intervals on tubing.

Measurement at one point is adequate for small components. Temperature control should be to ± 1°C. A continuous

record of temperature during the test shall be maintained.

7 Procedure

7.1 Blank Tests — A blank test shall be carried out after each calibration. If initial dry-down testing of components

is not of interest, the initial dry-down test of the test blank may be omitted and the test blank brought to equilibrium

with zero gas in whatever manner is most convenient, except that the test blank should not be heated above 200°C.

Permanent changes in moisture interaction have been observed at temperatures above this level.

SEMI F27-0997 © SEMI 1997, 2003 4

7.1.1 Initial Dry Down — Start the experiment with the

blank in place of the test specimen and a flow of dry

gas through the APIMS. The APIMS output should be

at equilibrium with the lowest moisture level of interest,

and in any case no higher than 500 ppt. The flow rate

through the test blank should be set according to the

Flow Table (see Table 1).

7.1.1.1 Switch the gas flow to pass primarily through

the bypass loop while maintaining a small flow through

the test blank. Remove the test blank completely from

the system. If a glove box or other such enclosure is

used, do not remove the test blank from the glove box.

Immediately reconnect the test blank to V

, leaving it

disconnected from V

. Allow dry nitrogen to flow

through the test blank for five minutes to purge the air

from inside before reconnecting to V

. Switch the gas to

flow only through the blank and not through the bypass

loop. The APIMS will show an increase in moisture

concentration. Record the APIMS output until it

reaches 500 ppt or for 24 hours, whichever is less.

7.1.1.2 Repeat the above test twice for a total of three

data sets.

7.1.2 Moisture Input Test — After the APIMS has

returned to equilibrium with its initial moisture level,

switch the input gas to 50 ppb moisture (by switching

valves V

, V

, and V

simultaneously, if the

arrangement of Figure 1 is used) while recording the

APIMS response. Maintain this moisture input for 20

minutes. Switch the input to the test blank back to dry

nitrogen and record the decease in moisture level until

the initial background is again reached.

7.1.2.1 Repeat the above test twice for a total of three

data sets.

7.2 Tests on Actual Specimen

7.2.1 Initial Dry Down — This portion of the test is

designed to determine the quantity of removable

moisture on the wetted surfaces of a component in the

condition in which it is typically supplied. Thus, the

results of this test will reflect, by design, any

precautions which the supplier has taken to remove

moisture and maintain its dryness during shipping.

7.2.1.1 Start the test as in Section 7.1.1. The test

specimen should not be unpacked until after the APIMS

has equilibrated with the background moisture level. If

a glove box or other such enclosure is used, unpack the

component in the glove box. Switch the dry nitrogen

flow to pass through the bypass loop while maintaining

a small component through the test blank. Undo the

final layer of packing and any shipping caps or plugs on

the component at this point. Remove the sample blank

and connect the test specimen to valve V

as quickly as

possible. Allow the dry nitrogen flow to purge out any

ambient air in the specimen for five minutes, then

connect the specimen to V

. Switch the gas to flow only

through the test specimen and not through the bypass

loop. The APIMS will show an increase in moisture

concentration. Record the APIMS output until it

reaches 500 ppt or for 24 hours, whichever is less.

7.2.1.2 After 24 hours, the dry-down part of the test

can be terminated. If necessary, the moisture level can

be reduced below 500 ppt by baking the component at

200°C or the maximum temperature allowed by the

manufacturer for six hours and/or purging at the highest

flow of dry gas available. If this is not sufficient to

reduce the moisture concentration below 500 ppt, the

test may be abandoned.

7.2.2 Moisture Input Test — After the APIMS has

returned to equilibrium with its initial moisture level,

switch the input gas to 50 ppb moisture (by switching

valves V

, V

, and V

simultaneously, if the

arrangement of Figure 1 is used) while recording the

APIMS response. Maintain this moisture input for 20

minutes. Switch the input to the test blank back to dry

nitrogen and record the decease in moisture level until

the initial background is again reached.

7.2.2.1 Repeat the above test twice for a total of three

data sets.

7.2.2.2 In case the moisture level recorded by the

APIMS does not reach 50 ppb within 20 minutes, an

additional test should be performed in which the

moisture input should be continued until equilibrium is

reached. Then switch the input to the test specimen

back to dry nitrogen and record the decease in moisture

level until the initial background is again reached.

This test should be repeated once (two data sets total).

7.2.3 Bake-Out Test — Heat component to maximum

bake temperature, according to manufacturer’s

specifications, for three hours. Allow it to return to

room temperature. Continue by repeating the moisture

input test, after baking, as in Section 7.2.2.

7.3 Temperature, Flow Rate, and Pressure

Specification — The recommended test pressure is 700

kPa (7 bar). However, lower test pressures are

appropriate for some models of APIMS. Also, the

maximum pressure rating of the test components should

not be exceeded. The component temperature shall be

maintained at 35 ± 1°C during the test.

7.3.1 In the case of tubing, the test shall be carried out

at a single flow determined by the tubing diameter

according to the following table. In the case of valves,

regulators, mass flow controllers (MFC’s), and passive

components (gauges, flow meters, and fittings), the test

will be carried out at a single flow determined by the

table according to the size of the connecting tube stubs.

SEMI F27-0997 © SEMI 1997, 2003 5

Regulators should be tested in the fully-open condition

(i.e., with the regulator adjusted for minimum pressure

drop). The quantity of published data on regulator

interaction with moisture is limited, and experiments to

investigate the effect of varying the pressure drop

across the regulator are encouraged but are not part of

this test. MFC’s should be tested with a flow control

device upstream and the MFC not actively controlling

the flow through it (usually referred to as the “purge”

setting). It may not be possible to test a given MFC at

the specified flow if the flow rating of the MFC is much

less than the specified flow. As MFC’s are not expected

to vary greatly in performance according to their flow

rating, MFC’s to be tested should generally be chosen

to be compatible with the table. If this is not possible,

then the MFC should be tested at its rated flow (lower

than the flow in the table). This can then be considered

a conservative test, as the MFC operated at higher flow

would be expected to dry down more quickly.

7.3.2 Particle filters with the same size tubing

connectors often have somewhat different sizes and

very different flow ratings. In order to be able to make

reasonable comparisons between the performance of

different filters, it is essential to test filters of similiar

size at the same flow. However, the flow dependence of

the moisture response of particle filters is more

complex than that of tubing, and they must be tested at

more than one flow in order to model their behavior. In

order to meet this requirement and provide data which

can be readily compared with the conditions under

which the filters can be expected to be used in practice,

filters shall be tested at two flows: The first, according

to the size of the connecting tube stubs, the second, to

be 25% of the rated flow of the filter or 50 slm,

whichever is less.

7.3.3 For systems of components, the system shall be

tested at the lowest flow of those determined for each

component in the system considered separately. If the

system includes a filter, it shall be tested at that flow

and additionally, at 25% of the rated flow of the filter or

50 slm, whichever is less.

Table 1 Flow Rate

Tubing Outer Diameter

(nominal)

Flow (all

components)

Flow for Second

Test on Filters

≥ 1/8", < 1/2"

(≥ 3.2 mm, < 12.7 mm)

6 slm

≥ 1/2"

(≥ 12.7 mm)

13 slm

25% of rated flow

or 50 slm

whichever is less

8 Reporting Results

8.1 Complete moisture response curves for all test

specimens and relevant test blanks should be included.

A summary sheet may compare components in terms of

“induction time,” peak height, and/or decay time.

Temperature, pressure, and flow measurements, and as

complete a record as possible of all experimental

variables should be noted.

NOTICE: SEMI makes no warranties or

representations as to the suitability of the standards set

forth herein for any particular application. The

determination of the suitability of the standard is solely

the responsibility of the user. Users are cautioned to

refer to manufacturer’s instructions, product labels,

product data sheets, and other relevant literature

respecting any materials mentioned herein. These

standards are subject to change without notice.

The user’s attention is called to the possibility that

compliance with this standard may require use of

copyrighted material or of an invention covered by

patent rights. By publication of this standard, SEMI

takes no position respecting the validity of any patent

rights or copyrights asserted in connection with any

item mentioned in this standard. Users of this standard

are expressly advised that determination of any such

patent rights or copyrights, and the risk of infringement

of such rights, are entirely their own responsibility.

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consent of SEMI.