IPC-TM-650 EN 2022 试验方法.pdf - 第180页

6.3.2 Determine the surface area per Section 3. 6.3.3 Calibration A precise quantity of sodium chloride calibration solution is injected into a designated volume of the test solvent mixture in the sample measurement cell…

to accelerate extraction of ionic soils from poorly accessible

places such as under surface mounted components.

5.3 Procedure

5.3.1 Solvent Systems

Industry has established two differ-

ent standard test solutions that are used worldwide:

75 % / 25 %, nominal v/v 2-propanol/DI water

50 % / 25 %, nominal v/v 2-propanol/DI water

Select the solution required by the specification (e.g., industry

standards, engineering drawing specifications, contract docu-

mentation, etc.).

5.3.2 Determine the surface area per Section 3.

5.3.3 Calibration Once the fluid in the system has estab-

lished a stable level of conductivity, a precise quantity of a

sodium chloride calibration solution is injected into the test

solution in the test tank. This is done according to the calibra-

tion instructions provided by the manufacturer of the equip-

ment.

Note: System calibration should be verified daily, when used.

5.3.4 Testing Once the system has been calibrated or veri-

fied in accordance with 5.3.3, immerse the test specimen into

the sample tank. The test time should be in accordance with

the monitoring plan criteria (set time or auto-shutoff). Use

clean gloves when handling the samples to be tested. Finger

dirt contains ionic soils which may contribute to false read-

ings. During the course of the measurement, the conductivity

will rise from the initial baseline level and then gradually return.

When it has returned to the baseline level, no additional ionic

material can be removed and the measurement is complete.

5.4 Interpretation of Test Data The number obtained

from this type of measurement indicates the total amount of

ionic material extracted from the entire sample in terms of

equivalent amounts of sodium chloride (assuming the calibra-

tion was done with sodium chloride). This should be divided

by the total surface area of the sample from which the ions

were extracted to determine the surface ionic density of the

original sample.

Important Parameters The following parameters must be

specified:

a) Solvent composition

b) Solvent volume for static method or flow rate for dynamic

method

c) Test temperature

d) Calibration of system

e) Sample area calculation

f) Test time

g) Equipment type and model number

The actual surface ionic density is most commonly calculated

by programming the area into the instrument’s microproces-

sor system. The total ionic amount will then be automatically

divided by the area to indicate surface ionic density in terms

of micrograms of sodium chloride equivalence per unit of sur-

face area (µg NaCl eq./cm

6 Static Extraction Method

6.1 Description

In the static extraction method, a mea-

sured volume of freshly deionized 2-propanol/DI water mixture

is introduced into the test tank and its resistivity (or conductiv-

ity) measured continuously while the 2-propanol/DI water mix-

ture is agitated. Once the system has been calibrated or veri-

fied in accordance with 6.3.3 and solution has been run

through the ion exchange columns, the test specimen is

immersed into the tank. The test time should be in accor-

dance with the monitoring plan criteria (set time or auto-

shutoff). Care must be taken not to handle the sample or any

of the appliances used to insert it into the tank. Finger dirt

contains ionic soils which may contribute to spurious read-

ings. During the course of the measurement, the conductivity

will rise from the initial baseline and then level off. When it has

stabilized and no additional ionic material can be removed

then the measurement is complete. After the test is completed

the solvent mixture is passed through ion exchange columns

to remove ionic materials and regenerate the 2-propanol/DI

water solvent mixture to its original high resistivity level for fur-

ther tests.

6.2 Test Equipment A static conductivity measurement

system includes a test tank, a temperature-compensated

conductivity cell and monitor, means for solution agitation and

a means for removing, deionizing and re-introducing the sol-

vent mixture into the test tank before a new test is started.

The equipment may also have the capability of heating the

2-propanol/DI water mixture to accelerate and improve the

efficiency of extraction of ionic material from poorly accessible

regions, such as under surface-mounted components.

6.3 Procedure

6.3.1 Solvent Systems

See 5.3.1.

IPC-TM-650

Number

2.3.25

Subject

Detection and Measurement of Ionizable Surface Contaminants by

Resistivity of Solvent Extract (ROSE)

Date

11/12

Revision

Page4of5

6.3.2 Determine the surface area per Section 3.

6.3.3 Calibration A precise quantity of sodium chloride

calibration solution is injected into a designated volume of the

test solvent mixture in the sample measurement cell. This is

done according to the calibration or verification instructions

provided by the manufacturer of the equipment being used.

6.3.4 Testing Once the system has been calibrated or veri-

fied in accordance with 6.3.3, the sample tank is filled as

directed by the procedures of the equipment manufacturer

and the test specimen is immersed in the tank. The minimum

starting resistivity for this type of equipment is machine

dependent. Use clean gloves when handling the samples to

be tested. Finger dirt contains ionic materials which may con-

tribute to spurious reading. During the course of the measure-

ment, the resistivity will fall continually as ionic material is

extracted into solution. If conductivity is being monitored, it will

initially be very low, rising continually as ionic material is dis-

solved from the sample. The test can be terminated when

there is no further change, in time, of the resistivity or conduc-

tivity function. This can be established electronically in most

commercially available equipment. The initial and final values

together with the volume of the solvent mixture in the test

tank, and sample surface area are used by the system to cal-

culate the ionic levels which were present on the sample sur-

face prior to the test.

6.3.5 Refer to the manufacturer’s equipment manual for

optimal operation.

6.4 Interpretation of Test Data See 5.4.

7 Notes

7.1 Temperature

Higher solution temperatures will result

in higher levels of extracted ionic material. Most machines

have calculation algorithms which incorporate the solution

temperature. Refer to the machine documentation to under-

stand how temperature affects the ionic contamination read-

ing.

For process control testing, temperature should be set at a

constant value for periodic measurements. All calibrations of

the equipment should be made at the same solution tempera-

ture used to run the test.

7.2 It is critical to always use test solution with the same

composition of electronic grade 2-propanol (isopropyl

alcohol)/DI water for all comparative data discussions.

7.3 It is also suggested that a solution blank of 5 mL of

2-propanol/DI water be run at time of calibration to determine

the foundational cleanliness of the testing system.

7.4 Specific pieces of test equipment only have contamina-

tion output displays of two digits, if results are greater than or

equal to 100 the actual results will be lost and only the last

two digits will be displayed.

7.5 An extremely ‘‘dirty’’ sample can exceed machine maxi-

mums. Refer to the equipment documentation to determine

the maximum reading of the instrument.

8 References

IPC-TM-650, Test Method 2.3.28

Ionic Analysis of Circuit

Boards by Ion Chromatography

IPC-TP-1113 Circuit Board Ionic Cleanliness Measurement:

What Does It Tell Us?

IPC-HDBK-001 Handbook and Guide to Supplement J-STD-

001

IPC-TM-650

Number

2.3.25

Subject

Detection and Measurement of Ionizable Surface Contaminants by

Resistivity of Solvent Extract (ROSE)

Date

11/12

Revision

Page5of5

Scope

This

test is used to determine the total ionic con-

tent extractable from on, and absorbed within, the surface of

printed wiring boards (PWBs), for the purposes of process

control. The conductivity of the extract solution is measured

and the results are expressed as sodium chloride equivalence

per unit area.

Applicable Documents

IPC-TM-650

Test

Method 2.3.25, Detection and Measure-

ment of Ionizable Surface Contaminants by Resistivity of Sol-

vent Extract (ROSE)

Test Specimens

The

test specimen may be any unpopulated PWB. The num-

ber of specimens depends on the process control plan or

product drawings/prints.

Apparatus or Material

•

An automated Resistivity of Solvent Extract (ROSE) tester

• Conductivity dip probe with appropriate meter with tem-

perature compensation

• Hydrometer (0.800 - 0.900) for ROSE tester calibration

• Thermometer for ROSE tester calibration

• Clean room (non-ionic) gloves or forceps

• KAPAK™ plastic bags or equivalents (see 6.9)

• Bag sealing equipment

• Water bath, capable of sustaining an 80°C ± 2°C [176°F ±

3.6°F] temperature

• Second water bath capable of sustaining a 25°C ± 1°C

[77°F ± 1.8°F] temperature

• Precision solvent measurement equipment, such as class A

pipettes

• Volumetric glassware

• Plastic ware - high density polyethylene, polymethylpentene

(polypentene) or equivalent.

• Extract solution: 25% v/v deionized water (18 MΩ-cm nomi-

nal resistivity), 75% v/v 2-propanol (electronic or HPLC

grade). No alternative solution or composition is allowed.

• Sodium chloride - reagent grade

• Analytical balance accurate to 0.0001 grams

ARNING: 2-propanol is a flammable material. The 2-propanol /

water mixture is also flammable. Exercise caution when using this

solution.

5 Procedure

5.1 Extraction

NOTE: Throughout

this procedure, do not touch the sample

boards with bare hands. Use the clean room gloves specified

or use clean forceps.

5.1.1

Calculate

the surface area of the PWB using:

Area

(in cm

)

= Length x Width x 2

5.1.2

Prepare

a volume of extract solution specified in 4.

5.1.3

Using

clean room gloves or clean forceps, place the

PWB into virgin KAPAK™ bags. Choose the bag size to give

at least an additional 2.5 cm [1.0 in] on each side of the board

to minimize the amount of extract solution used. Allow at least

an additional 5 cm [2.0 in] above the board top.

5.1.4

Using

a pipette or graduated cylinder, add a volume of

the extract solution into the bag. The amount will depend on

the area of the board surface. This usually varies from 0.8

mL/cm

[5.2

mL/in

]

up to about 3 mL/cm

[19

mL/in

For

example, a 10 cm x 11.5 cm [3.94 in x 4.53 in] board would

require about 100 mL of solution. The amount of solution

should just cover the board completely when most of the air

is forced out of the bag.

5.1.5

Force

most of the air from the bag and heat seal the

bag. This involves contact with a hot metal bar. Take reason-

able precautions to keep extract solution from contacting the

hot bar. Alternatively, the top of the bag may be folded over

and clipped shut.

5.1.6

Place

the bag(s) vertically in a water bath which has

stabilized at 80°C [176°F]. Make sure that the boards do not

float above the water line. Do not allow the water from the

bath to enter the bag or for extract solution to leak out of the

bag.

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.3.25.1

Subject

Ionic

Cleanliness Testing of Bare PWBs

Date

October 2000

Revision

Originating Task Group

Bare Board Cleanliness Assessment Task Group

5-32c

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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