IPC-TM-650 EN 2022 试验方法.pdf - 第175页

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 …

1.0

Outline for Methods

The

part is exposed to an atmo-

sphere that is corrosive to the basis metal. Where there is

porosity, the reagent attacks the basis metal and generates

corrosion products. The part is examined for corrosion prod-

ucts.

1.1

Method 1 (Nitric Acid Vapor-Gold on Copper)

This

method

applies only to gold coatings on copper and copper-

base alloys.

1.2

Method 2 (Extended Nitric Acid Vapor)

This

method

applies only to gold coatings on copper and copper-base

alloys.

1.3

Method 3 (Nitric Acid Vapor - Gold on Nickel)

This

method

applies to gold coatings on copper, copper-base

alloys, and nickel.

2.0

Nitric Acid Vapor - Gold on Copper

2.1 Apparatus

Methods

1, 2, and 3.

2.1.1

Collimated Incandescent Lamp

No.

31-33-53,

Bausch and Lomb Co., or No. 359, American Optical Co., or

equivalent.

2.1.2

Desiccator (Glass)

Fisher

Scientific Co. Series

8-595 or 8-624 or equivalent. The size of the desiccator shall

be chosen so that no more than 164 cm

air space exists

for 6.45 cm

nitric acid surface area when approximately

301 ml of acid are placed in the bottom.

Caution:

No sealant (e.g., stopcock grease, etc.) shall be

applied to the mating surfaces of the desiccator cover or

bottom. Sealants may cause these to stick together, and any

method employed to release a stuck cover is likely to be

extremely hazardous.

2.1.3

Part Support

supporting structure made of glass

or other material not attached by nitric acid vapors to hold the

parts under test in the upper part of the desiccator.

2.1.4

Oven

oven capable of drying parts at 125°C.

2.1.5

Pressure Sensitive Polytetrafluoroethylene Tape

with Silicone Adhesive Backing

Connecticut

Hard Rubber

Company TFE Type HM225 or equivalent.

2.2

Reagents

Methods

1 and 2. Nitric Acid, 69, 0 to 71.0

Percent HNO

3.0

Procedure

3.1 Method 1 (Nitric Acid Vapor-Gold on Copper)

Caution:

Perform all work in hood, since the vapors given off

are toxic. Chemical goggles, completely closing the eyes,

should be worn and eyewash facilities should be readily

available.

minimize and tendency for the cover to stick, press a mini-

mum of three strips of the pressure polytetrafluoroethylene

tape (adhesive side down) at equal intervals around the mat-

ting surface of the bottom of the desiccator. Place approxi-

mately 300 ml of nitric acid in the bottom of the desiccator.

Cover the desiccator and allow about 30 minutes for equilib-

rium to be established before starting the test. This equilibrium

is necessary only when the nitric acid is first placed in the

desiccator.

Clean the part with 1,1,1-trichloroethane or toluene or other

suitable solvent and dry with filtered dry air (gage pressure

less than 207 kPa (30 psi)).

Inspect the cleaned part at 10 power magnification for evi-

dence or particulate matter of the surface. If any remains,

reclean the solvent or use a clean soft brush to remove it prior

to the start of the porosity test.

Place the clean part on the support so that adequate space

exists to allow circulation of acid vapor and air around it.

Carefully remove the desiccator cover, place the support in

the desiccator and immediately replace the cover to prevent

an excessive loss of vapors that would disrupt the equilibrium

previously established. The test shall be performed at a tem-

perature of 24 ± 3°C and a maximum relative humidity of 60

percent. Unless otherwise specified, the time of exposure to

the reagent vapor shall be one hour.

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.3.24.2

Subject

Porosity

of Metallic Coatings on Copper-Base

Alloys and Nickel (Nitric Acid Vapor Test)

Date

8/97

Revision

Originating Task Group

N/A

Material

in this Test Methods Manual was voluntarily established by Technical Committees of the 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 the IPC.

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ASSOCIA

TION CONNECTING

ELECTRONICS INDUSTRIES

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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.

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