IPC-TM-650 EN 2022 试验方法.pdf - 第684页

1 Scope This test method is used to determine the total mass loss (TML) and collected volatile condensable material (CVCM) of materials when exposed to a heated vacuum envi- ronment. Mass loss may be due to outgassing of…

of one, even though there are four distinct comb patterns and

measurements.

7.1.2 Sample Sizes The number of samples should not be

stipulated in the test method. The number should be in the

specifications referring to this test method. However, it is rec-

ognized that there will be users who are attempting process

or material characterization and may be uncertain about how

many samples to specify.

With respect to the second bulleted item in the scope, (Pro-

vide metric(s) that can appropriately be used for binary classi-

fication (e.g., go/no go, pass/fail), a minimum sample size of

10 is suggested.

With respect to the third bulleted item in the scope, (Compare,

rank or characterize materials and processes) a minimum

sample size of three is suggested.

7.1.3 When characterizing material, samples can be pro-

cessed on the same panel.

7.1.4 When characterizing process(es), samples should at a

minimum be processed on different panels, preferably in dif-

ferent production runs.

7.2 The derived unit of surface resistivity and its expression

as ohm/square cannot be defined for this method or similar

methodologies due to the nonlinear response of the test

vehicles and the assumed nonhomogeneous concentration of

ionic contaminates.

7.3 Careful considerations must be used when developing

an implementation of this method. Seemingly adequate set-

ups can (and historically have) caused unacceptable uncer-

tainty of results. If the user of this method is not intimately

familiar with the technologies involved, ASTM D 257 and IPC-

9201 are highly recommended.

IPC-TM-650

Number

2.6.3.7

Subject

Surface Insulation Resistance

Date

03/07

Revision

Page4of4

Scope

This

test method is used to determine the total

mass loss (TML) and collected volatile condensable material

(CVCM) of materials when exposed to a heated vacuum envi-

ronment. Mass loss may be due to outgassing of low molecu-

lar weight materials present in printed boards such as trapped

plating solutions, improper lamination, and uncured adhesives

which are known to cause contamination or corrosion of

spacecraft equipment.

Applicable Documents

NASA General Speciﬁcation No. SP-R-0022

Vacuum

Sta-

bility Requirements of Polymeric Material for Spacecraft Appli-

cation.

ASTM

E 595

Standard

Test Method for Total Mass Loss and

Collected Volatile Condensable Materials from Outgassing in a

Vacuum Environment.

Test Specimens

The

test specimen shall be cut into

small pieces that can fit into the specimen boats and whose

total mass shall be about 200 mg. If smaller masses are used

the accuracy of the TML and CVCM determinations may be

impaired. It is imperative that the specimens not be contami-

nated during the preparation process. Specimens are not to

be handled with bare hands since human skin oils are volatile

and condensable by this method thereby creating misleading

TML and CVCM results. If there is any doubt about specimen

contamination the specimens should be cleaned using sol-

vents known to be nonreactive and that leave no residue. An

average of at least three (3) samples shall be made for each

test.

Apparatus or Material

4.1

Multiple

specimen vacuum chamber capable of main-

taining a vacuum of at least7X10

-3

(5 X 10

-5

Torr)

with

resistance heated copper bars capable of maintaining 125 °C

± 1 °C [257 °C ± 1.8 °F] during the 24 hour test run and typi-

cally containing 24 specimen chambers. Typically, three (3) of

the specimen chambers are maintained as controls. The open

end of each specimen chamber allows vapors from the speci-

men to pass through a hole into a collector chamber where

the vapors are condensed on a collector plate that is main-

tained at 25 °C ± 1 °C [77 °F ± 2 °F) throughout the test. See

ASTM E 595 for further details and requirements for the con-

struction and cleaning of the test apparatus.

4.2

analytical balance capable of measuring the speci-

mens, boats, and collector plate mass to the nearest micro-

gram (0.000001 gram).

4.3 Glass

desiccator using active silica gel desiccant. Low

vapor pressure grease shall be used for the ground glass

joints.

4.4

Conditioning

chamber capable of maintaining 50% ± 5%

relative humidity and 23 °C ± 2 °C [73 °F ± 4 °F).

4.5

Prepared

aluminum foil specimen boats.

4.6

Suitable cleaning solvents

Mixtures

of 1:1:1 by vol-

ume chloroform:acetone:ethanol and 1:1 by volume

acetone:ethanol solvent blends have been successfully used

for cleaning and degreasing the apparatus, aluminum boats,

and collector plates. All solvents shall be spectrophotometer

grade purity or equivalent. See Annex A1 of ASTM E 595 for

details regarding cleaning and storage procedures for the

equipment used in this test.

4.7

Nitrogen

gas, 99.9% pure, or better, with a dew point of

-60 °C [-76 °F] or less. The nitrogen gas shall be filtered using

a Molecular Sieve 5A or equivalent.

4.8

Wiping

materials and swabs for cleaning. These material

shall be preextracted using solvents with which they will be

used.

4.9

Suitable

gloves or finger cots to be used during sample

preparation.

Procedure

5.1

Weigh

a prepared aluminum foil boat to the nearest

microgram and return it to the glass storage desiccator.

5.2

Weigh

a prepared collector plate to the nearest micro-

gram and mount it into its cooling plate receptacle.

5.3

Add

the test specimen to the boat and condition the

specimen at 50% ± 5% relative humidity at 23 °C ± 2 °C

[73 °F ± 4 °F] for a minimum of 24 hours. Weigh the condi-

tioned specimen and boat to the nearest microgram.

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.6.4

Subject

Outgassing,

Printed Boards

Date

05/04

Revision

Originating Task Group

Rigid Printed Board Performance Task Group

(D-33a)

Material

in this Test Methods Manual was voluntarily established by Technical Committees of IPC. This material is advisory only

and its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this

material. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement.

Equipment referenced is for the convenience of the user and does not imply endorsement by IPC.

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5.4

Exposure

5.4.1

Prior

to operation, all temperature-vacuum apparatus

such as the heating bar, separators, and cooling plates shall

be clean and aligned.

5.4.2

Place

the test specimen and boat into the specimen

compartment in the temperature-vacuum system. Mount the

respective cover plates of each specimen compartment and

at least three (3) control compartments.

5.4.3

and activate the vacuum system and allow the

system to evacuate to 7.0 X 10

-3

(5 X 10

-5

Torr)

or less

within one hour. During this period, control of the collector

plate temperature at 25 °C ± 1 °C [77 °F ± 2 °F] shall be

achieved.

5.4.4

When

the required vacuum has been achieved, turn

on the heater bar and adjust the controller to heat the bar to

125 °C ± 1°C [257 °F ± 2 °F] within 60 minutes.

5.4.5

Maintain

the collector plate temperatures at 25 °C ±

1 °C [77 °F ± 2 °F] and the heater bar temperature at 125 °C

± 1 °C [257 °F ± 2 °F] for 24 hours. After this time period close

the vacuum valve to the pumping system and turn off the cur-

rent to the heater bars.

5.4.6

Open

the vent valve and backfill with clean, dry nitro-

gen at a gage pressure of 10 to 30 kPa (2 to 4 psi) above

atmosphere to rapidly cool the bars to 50 °C [122 °F] within

two hours, nominally.

5.4.7

Turn

off the collector-plate heat exhchangers, return

the vacuum chamber to room pressure using clean, dry nitro-

gen, and open the chamber. Remove the aluminum specimen

boats and their respective collector plates and the control col-

lector plates and immediately store in the dry desiccator (see

4.3).

5.4.8

After

allowing the specimens to cool to approximately

room temperature, but after no more than 1/2 hour, weigh the

specimens and boats and the collector plates to the nearest

1 microgram within two minutes of removal from the desicca-

tors.

5.5

Evaluation of Test

5.5.1

Measurements

of the control collector plates are used

to detect contamination and/or poor technique. Mass loss of

greater than 20 micrograms is an indication of poor cleaning

of the collector plates. Mass gain of greater than 50 micro-

grams is an indication of poor cleaning of elements of the

apparatus, cross contamination between specimen compart-

ments, or poor vacuum technique. Any change of 50 micro-

grams or greater calls for a review of or change in technique.

All data obtained during such runs shall be discarded and the

test rerun when the system(s) are corrected.

5.5.2

Calculation

of Total Mass Loss (TML). Calculate the

TML as follows:

Initial Mass Final Mass

Specimens Weights:

)-B S

)-B

Mass Loss (L) = S

-S

Total

Mass Loss (TML) (%) = (L/S

)

X 100

Where:

B = Mass of boat in grams

Initial specimen mass in grams

Final Specimen mass in grams

L = Mass Loss in grams

5.5.3

Calculate

the Collected Condensable Volatile Material

(CVCM) as follows:

Mass of condensable material (C

)=C

-C

CVCM

(%) = (C

)

X 100 Where:

Final mass of collector plate in grams

Initial mass of collector plate in grams

Mass of condensable material in grams

Initial specimen mass in grams

6 Notes

6.1

useful outgassing test data sheet format can be found

in Appendix X1 of ASTM E 595.

6.2

Additional

information regarding this test method and

suggested requirements for certain spacecraft applications

can be found in NASA SP-R-0022.

IPC-TM-650

Number

2.6.4

Subject

Outgassing,

Printed Boards

Date

05/04

Revision

age2of2

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