IPC-TM-650 EN 2022 试验方法.pdf - 第176页

1 Scope 1.1 Purpose These tests are used as process control tools; they can be used to inspect printed boards or printed board assemblies and determine if they conform to the moni- toring level of the user’s performance …

Remove

the part from the desiccator and immediately transfer

it to an oven at 125°C for 30 minutes. Remove and inspect

the part with 10 power magnification using the collimated

incandescent light source arranged so that the light beam

strikes the surface being examined at an angle of less than 15

degrees. The presence of blue, green, or bluish-white protru-

sions indicates that the coating is discontinuous (i.e., porous,

scratched, etc.) at these spots. The acceptable number,

sizes, and location of these protrusions shall be as specified

on the appropriate drawing or specification.

3.2

Method 2 (Extended Nitric Acid Vapor-Gold on

Copper)

Procedure

This

method is an extension of method 1 and

may be used only after the test specimen has passed the

requirements of the visual examination with the collimated

light source. The method permits the determination of the

actual sizes of the larger pores. The inspection should be per-

formed as indicated below.

After examining the oven-dried test specimen in accordance

with Method 1, brush the corrosion products from the speci-

men. Inspect the area where the corrosion products appeared

at a magnification that permits measurements of the largest

dimensions of the discontinuities with reasonable accuracy.

The acceptable distribution of pore sizes shall be as specified

on the appropriate drawing or specification.

3.3

Method 3 (Nitric Acid Vapor-Gold on Nickel)

3.3.1 Apparatus

The

apparatus described in methods 1

and 2.

3.3.2

Reagents

Nitric

acid, 69.0 to 71.0 percent HNO

Sodium

Hydroxide 10 percent by weight solution. Polysulfide

reagent.

3.3.3

Procedure

Caution:

Perform all work in a hood,

since vapors given off are toxic. Chemical goggles, com-

pletely enclosing the eyes, should be worn and eye wash

facilities should be readily available.

Use the procedure for Method 1 up to removal from nitric acid

vapors.

At the end of the one hour exposure to the nitric acid vapors,

remove the part from the desiccator and immediately dip it in

the 10 percent by weight sodium hydroxide solution for 25 to

30 seconds at room temperature. Rinse the part with water

and then dip it for 25 to 30 seconds in the polysulfide reagent

at room temperature. Then rinse it in water and dry using fil-

tered compressed air (gage pressure less than 207 kPa).

Inspect the part at 10 power magnification. The presence of

black corrosion products is evidence of porosity. The accept-

able number, sizes, and locations of pores shall be as speci-

fied on the appropriate drawing or specification.

3.4

Polysulfide Reagent Makeup

Dissolve

sodium sulfide

crystals in water until solution is saturated. Add excess flow-

ers of sulfur (more than 250 grams per 1000 ml). Stir and

allow solution to stand 24 hours. Filter and dilute with water to

a specific gravity of 1.142 at room temperature as defined in

ASTM Designation E 41. The solution should be a red-orange

color.

To check reagent effectiveness, dip a clean copper or high

(more than 95 percent) copper alloy specimen into the reagent

at room temperature as defined in ASTM Designation E 41. It

shall blacken within 10 seconds.

IPC-TM-650

Number

2.3.24.2

Subject

Porosity

of Metallic Coatings on Copper-Base Alloys and Nickel

(Nitric Acid Vapor Test)

Date

8/97

Revision

age2of2

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1 Scope

1.1 Purpose

These tests are used as process control

tools; they can be used to inspect printed boards or printed

board assemblies and determine if they conform to the moni-

toring level of the user’s performance specification. Bulk ionic

cleanliness testing may be accomplished by measuring the

ionizable surface contaminants extracted by the following

three methods:

1. Manual extraction method

2. Dynamic extraction method

3. Static extraction method

Note: Please note that this method does not predict reliabil-

ity and should only be used as a process control tool.

1.2 Restrictions Measurements of ionic conductivities do

not differentiate between different ionic species. They simply

measure conductivities (or resistivities) which can be related to

amounts of ionic materials present in solution. There is no

identification of the contribution to the total conductivity read-

ings of any individual ionic species which may be extracted

into the solution. For measurement of individual ionic species

(type and level of residue) see IPC-TM-650, Test Method

2.3.28, Ionic Analysis of Circuit Boards, Ion Chromatography

Method.

For simplicity, amounts of ionic materials in solution can be

expressed by a conductivity factor which is equivalent to the

measured conductivity contributed by a known amount of a

standard, strongly ionized salt such as sodium chloride (NaCl).

Ionic residues are therefore usually expressed as equivalents

of sodium chloride in micrograms per unit surface area (e.g.,

µg NaCl Eq./cm

) of the sample. This does not imply that the

contamination is NaCl but, rather, it exhibits a conductivity

function which is equivalent to that of the expressed amount

of sodium chloride if it were in solution instead of the ionic soil.

These tests will not measure any surface ionic materials which

are not brought into solution because of insolubility, physical

entrapment or inadequate exposure to the extracting solvent.

Additionally, non-ionic components of the soil will not be mea-

sured.

1.3 Application Caution should be exercised in comparing

results between different test equipment as well as the differ-

ent test methods. These methods are applicable as quality

control tools in evaluating the parameters of materials and

cleaning process, in terms of how they affect the final cleanli-

ness of the board or assembly. As process control tools, they

can be used to inspect printed wiring boards or printed wiring

assemblies and determine if they conform to the requirements

of the user’s performance specification. It is important to

understand, no calculation factor can exist to convert data

from one style of commercial tester to another due to the

great differences in system responses. See IPC-TR-583. This

means it is very difficult to compare data from different

machines. These procedures can also be used to assist

in-process development as general residue indicators, to

evaluate flux cleanability, solvent efficiency and general

improvements of process parameters.

Note: Please note that this method does not predict reliabil-

ity and should ONLY be used as a process control tool.

2 Applicable Documents

IPC-TR-583

An In-Depth Look at Ionic Cleanliness Testing

3 Test Specimen Follow the equipment manufacturer’s

recommendations as to sample size. Recommended area cal-

culations for the unpopulated printed board and printed board

assembly are the following:

Printed Board Surface Area = Length x Width x 2

Printed Board Assembly Surface Area = (Length x Width x 2)

+ (1 x up to 50% of the board area)

Report the surface area used in the calculation and the per-

centage increased in calculating the surface area of a printed

board assembly.

Note: There is no universally accepted method for determin-

ing the surface area of components. However, the determina-

tion of surface area for components should be established ini-

tially and used whenever that assembly style is being tested.

4 Manual Extraction Method

4.1 Description

This method describes the manual extrac-

tion of ionic material from the surface of a sample. This con-

sists of flushing the board surface with a stream of

2-propanol/DI water mixture and carefully capturing all of the

3000 Lakeside Drive, Suite 309S

Bannockburn, IL 60015-1249

IPC-TM-650

TEST METHODS MANUAL

Number

2.3.25

Subject

Detection and Measurement of Ionizable Surface

Contaminants by Resistivity of Solvent Extract (ROSE)

Date

11/12

Revision

Originating Task Group

Ionic Conductivity / Ion Chromatography Task Group

(5-32a)

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.

Page1of5

extraction solution before measuring the resistivity of the com-

posite sample.

4.2 Test Equipment and Chemicals

4.2.1

Miscellaneous laboratory ware (e.g., beakers, funnels,

storage bottles and graduated cylinders). This plastic ware

can be high density polyethylene, polymethylpentene (poly-

pentene), polypropylene or equivalent. Glassware cannot be

used because it has been shown to contribute ionic contami-

nation in a short time with this 2-propanol/DI water solution.

4.2.2 Conductivity bridge or equivalent conductivity probe

and temperature compensated liquid conductivity cell appara-

tus capable of measuring specific resistivities within a range

covering at least 100 kΩ-cm to 20 MΩ-cm.

4.2.3 Deionization column. Up to 100% solvent compatible

mixed bed or equivalent.

Note: Some of these columns are color dyed. This dye will

interfere with test results. Make certain that the column used

has no dye.

4.2.4 Electronic Grade 2-Propanol (isopropyl alcohol) or

99.5% purity minimum

4.2.5 Deionized water (DI water), preferably above 16

MΩ-cm water resistivity

Note: It is critical to always use wash solution with the same

composition of 2-propanol/DI water for all comparative data

discussions.

4.2.6 Wash solution composed of 75 ± 2% v/v 2-propanol/

DI water or 50 ± 2% v/v 2-propanol/DI water. This wash solu-

tion must be deionized to a resistance equal to or greater than

16 MΩ-cm (conductivity less than 0.0625 µS/cm). If stored,

this wash solution must be freshly deionized prior to use. Typi-

cal resistivity of 25 MΩ-cm (conductivity of 0.04 µS/cm) can

be achieved. Measurement of the 2-propanol/DI water solu-

tion should be performed using a calibrated hydrometer. The

default extract solution composition is 75 ± 2% v/v

2-propanol/DI water.

4.3 Calibration of Bridge This is essential in the manual

method because there can be no correlation between

resistivity/conductivity readings and NaCl equivalents without

calibration. All future specification requirements are to be

stated in maximum micrograms of NaCl equivalent per square

centimeter (µg NaCl Eq./cm

Note: Ensure that a proper cell constant value is considered

in any conductivity calculations. Check the specific conductiv-

ity bridge manufacturer’s manual for this detail.

4.3.1 Prepare or purchase (these standard solutions are

available from equipment vendors, as well as many of the

chemical companies) a standard NaCl solution from a weight

of ACS reagent grade NaCl salt dissolved in deionized water

(16 MΩ-cm resistivity minimum) to produce a final diluted con-

centration of 0.06 g/liter NaCl (5 mL contains 300 µg NaCl).

Note: It is recommended that dry NaCl be used for this solu-

tion. A recommended drying exposure is one hour at 105 °C

or higher.

4.3.2 Place one liter of the 2-propanol/DI water solution (at

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

beaker.

Note: The 75%/25% v/v or 50%/50% v/v 2-propanol/DI

water solution must be used in this calibration. Water cannot

be used since it is not the test solution used in the procedure.

The test solution used in this calibration should be made fresh

daily.

4.3.3 From a 50 mL burette, add to the liter of test solution,

5 mL of the standard 0.06 g/liter NaCl solution. Stir and mea-

sure resistivity/conductivity.

Note: If the resistivity is measured, convert to conductivity by

take the reciprocal, prior to plotting the data.

4.3.4 From a 50 mL burette, add to the liter of test solution,

20 additional mL of the standard 0.06 g/liter NaCl solution, for

a total of 25 mL. Stir and measure resistivity/conductivity.

4.3.5 From a 50 mL burette, add to the liter of test solution,

25 additional mL of the standard 0.06 g/liter NaCl solution, for

a total of 50 mL. Stir and measure resistivity/conductivity.

4.3.6 Plot a three-point nomogram of Conductivity vs.

µg/liter of NaCl. A linear relationship is expected with the use

of a linear regression best fit line through the data points. If a

multi-range meter is used the curve should not be extended

beyond the maximum reading of the meter for that range,

unless linearity is proven by additional points obtained by add-

ing more standard salt solution. The nomogram will never

cross the zero point of conductivity.

Note: An R

value of 0.99 should be expected before the

instrument would be considered calibrated.

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

Page2of5