IPC-TM-650 EN 2022 试验方法.pdf - 第181页

1 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…

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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5.1.7

Allow

the boards to extract in this manner for a period

of time of 60 ± 5 minutes.

5.1.8

Following the extraction of 5.1.7, remove the bags

from the water bath and allow the extract solution to cool for

at least 30 minutes, with the specimen still in the bag.

5.1.9

Using

clean tongs or forceps, remove the PWB from

the bag.

5.2

Measurement – DIP Probe Method

5.2.1 Calibration of Bridge

This

is essential in this method

because there can be no correlation between resistivity/

conductivity readings and NaCl equivalents without calibra-

tion.

5.2.1.1

Prepare

a standard NaCl solution from a weight of

dry reagent grade NaCl salt dissolved in deionized water to

produce a final diluted concentration of 0.06 g/liter NaCl (5 mL

equals 300 µg NaCl).

5.2.1.2

Place

1 liter of the 2-propanol water solution (at the

calibration temperature of the bridge in use) in a plastic bea-

ker.

NOTE: The 75 % v/v 2-propanol solution must be used in this

calibration. Water cannot be used since it is not the test solu-

tion used in the procedure. The test solution used in this cali-

bration can be recleaned by passing through the DI column

until the required resistivity/conductivity is obtained.

5.2.1.3 From

a 50 mL burette, add to the liter of test solu-

tion, 5 mL of the standard 0.06 g/liter NaCl solution. Stir and

measure resistivity/conductivity.

5.2.1.4

From

a 50 mL burette, add to the liter of test solu-

tion, 20 additional mL of the standard 0.06 g/liter NaCl solu-

tion, for a total of 25 mL. Stir and measure resistivity/

conductivity.

5.2.1.5

From

a 50 mL burette, add to the liter of test solu-

tion, 25 additional mL of the standard 0.06 g/liter NaCl solu-

tion, for a total of 50 mL. Stir and measure resistivity/

conductivity.

5.2.1.6

Plot

a three point nomogram of Conductivity vs.

Solution Concentration (in µg/liter NaCl). See Figure 1 for

example. You should get a linear relationship. Use a best fit

line obtained with a piecewise linear method.

5.2.2

Test Procedure - DIP Probe

NOTE: If

desired, this test can be run at other temperatures;

however, the calibration process must be repeated for the

alternative temperature. This calibration process need only be

done once, providing the conductivity cell has not been

exposed to harsh chemicals which would alter the cell con-

stants. If the conductivity cell is routinely used on harsh

chemical solutions (e.g., plating baths), then the calibration

should be repeated before every test run.

5.2.2.1

Place

the Kapak™ bags containing the extract solu-

tions into the 25°C [77°F] water bath and allow the extract

solutions to reach 25°C [77°F].

5.2.2.2

Insert

the conductivity probe into the Kapak™ bag

containing the room-temperature extract solution. It is impor-

tant that the extract solution be measured at the same tem-

perature used for the calibration solutions. Immerse the probe

to a suitable depth.

NOTE: A ‘‘suitable depth’’ is one which covers the cell elec-

trodes, but not an immersion which covers the wiring. Many

cells are marked with a scribed line which indicates the proper

immersion depth.

5.2.2.3

Gently

agitate the solution. Read the conductivity of

the solution. The time between immersion of the cell and tak-

ing the reading should be the same as used for the calibration

curve. Sufficient time should be allowed for the reading to

come to equilibrium (no change for two minutes).

IPC-2325-1

Figure

1 Nomogram of Conductivity vs. Solution

Concentration

Conductivity

Solution Concentr

ation

in micrograms NaCl/Liter

IPC-TM-650

Number

2.3.25.1

Subject

Ionic

Cleanliness Testing of Bare PWBs

Date

October 2000

Revision

age2of4

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