IPC-TM-650 EN 2022 试验方法.pdf - 第59页

6.4 Horizontal Microsection A performance standard may require, for referee inspections (such as smear, breakout, interconnect separations, etc.), a horizontal grind (perpendicu- lar to the original vertical plane) on a …

2) Activate the etchant with a copper solid (i.e., plated

copper/copper foil). Use a cotton swab to lightly rub a

piece of copper and return swab to solution.

3) Gently swab the surface of the microsection (outcome

based control: grain structure and plating interfaces are

slightly exposed).

4) Rinse with running tap or deionized water (quality is not

defined).

5) Rinse in suitable solvent (optional).

6) Blot dry with cloth or blow dry (outcome based control:

no nonconforming scratches caused by cloth, no oil or

debris from gas source).

b) Submersion

1) Activate the etchant with a copper solid (Using appro-

priate method).

2) Submerse microsection surface in etchant.

3) Provide a means to refresh the etchant at the surface

where the reaction is taking place (nominally 3 to 5 sec-

onds, outcome based control: grain structure and plat-

ing interfaces are slightly exposed).

4) Rinse with running tap or deionized water (quality is not

defined).

5) Rinse in suitable solvent (optional).

6) Blot dry with cloth or blow dry (outcome based control:

no nonconforming scratches caused by cloth, no oil or

debris from gas source).

5.6 Evaluation

5.6.1

Refer to the appropriate printed board performance

specification for magnification and evaluation requirements of

completed microsection.

6 Notes

6.1 Overplating

Overplating the specimen per ASTM E 3

with a layer of copper or other plating with a hardness similar

to the specimen, prior to encapsulation, provides better edge

retention, thereby providing more accurate final finish thick-

ness measurements. Plating can be done electrolytically or

with electroless solutions. Thoroughly clean the specimen sur-

face prior to plating to ensure good adhesion of the plating.

Milder cleaning treatments that involve detergents, solvents,

mild alkaline, or acidic solutions are recommended. Copper

and nickel are predominantly used in metallographic laborato-

ries. It is recommended that the plating thickness be at least

5 µm [0.0002 in]. This process is optional and is not for stan-

dard evaluation purposes.

6.2 Plating Separation Evaluation For a more accurate

evaluation of possible internal plating separations (e.g., inner

layer interconnect and via to target land separation), the fol-

lowing procedure is recommended to remove the etch demar-

cation line and return a micro-etched sample to an

as-polished condition:

1) With the wheel in a stationary position, gently and manually

regrind the specimen using copious amounts of water and

600 grit abrasive medium. Six to eight double strokes

should be sufficient. This action will remove any copper

metal smear that may have occurred over the plating sepa-

ration during rotary polishing.

2) Rinse and dry specimen and repolish per 5.4.3.1 and

5.4.3.2, then reexamine to determine if any internal plating

separation exists.

6.3 Polishing Considerations

• The use of napped cloths can result in poor edge retention

(rounding) and relief between constituents since it exacer-

bates the varying rates of material removal (i.e., tin-lead alloy

and the softer encapsulation media are removed at a faster

rate than the copper or glass fibers in the base material); the

higher the nap, the more the effect. The user needs to mini-

mize the polishing time and use ample lubricant and light

pressure during final polishing. When using diamond com-

pounds on soft woven cloths, final polishing may extend

several minutes.

• Reduced wheel speeds of 100 to 150 rpm are generally

used during final polishing due to increased drag on the

microsection.

• Typically, 6.0 µm [236 µin] followed by 1.0 µm [39.4 µin]

diamond and a 0.04 µm [1.57 µin] colloidal silica or 0.05 µm

[1.97 µin] alumina have been used successfully. However,

other variations such as 6.0 µm [236 µin], 3.0 µm [118 µin],

and 0.25 µm [9.84 µin] diamond have also been used suc-

cessfully. Some have even used 1.0 µm and 0.3 µm [39.4

µin and 11.8 µin] alumina on napless cloths followed by 0.05

µm [1.97 µin] alumina on a soft, medium napped cloth.

NOTE: Alumina and napped cloths can be used successfully,

depending upon the skill of the metallographer, but will gener-

ally result in poorer edge retention and more relief effects than

the diamond compounds (see Section 7, Reference 1).

IPC-TM-650

Number

2.1.1

Subject

Microsectioning, Manual and Semi or Automatic Method

Date

6/15

Revision

Page7of8

6.4 Horizontal Microsection A performance standard

may require, for referee inspections (such as smear, breakout,

interconnect separations, etc.), a horizontal grind (perpendicu-

lar to the original vertical plane) on a vertical microsection. This

method has a low success rate when the separation affects

less than 50% of the internal layer thickness (as noted on the

vertical microsection).

6.5 Etchants There are other etchant solutions that have

been used or that may be developed for etching copper. Care

must be exercised in their selection and use because of the

sensitive nature of the electrolytic, electroless, and foil etching

characteristics as well as possible galvanic effects in the pres-

ence of tin-lead (see Section 7, Reference 2, and IPC-MS-

810).

When studying tin-lead solders, it is sometimes helpful to use

etchants specifically designed to reveal those alloy’s micro-

structures (see Section 7, Reference 2).

7 References

Additional references on metallographic laboratory practice

include the following:

1) Metallographic Polishing by Mechanical Means, L.E.

Samuels, American Society for Metals, 1982, ISBN:

0-87170- 135-9.

2) Metallographic Etching, Gunter Petzow, American Society

for Metals, 1978, ISBN 0-87170-002-9.

3) Metallography Principles and Practice, George F. Vander

Voort, McGraw-Hill, 1984, ISBN: 0-07-0669780-8.

4) Metals Handbook Desk Edition, Edited by Howard E.

Boyer and Timothy L. Gall, American Society for Metals,

1985, ISBN: 0-87170-188-X.

IPC-TM-650

Number

2.1.1

Subject

Microsectioning, Manual and Semi or Automatic Method

Date

6/15

Revision

Page8of8

1.0

Scope

method for determining the presence of pin-

holes in metal foil by visual examination after applying a dye

penetrant.

2.0

Applicable Documents

None

3.0

Test Specimen

Specimen

must be a minimum of 12 in.

long by the full width of the roll or sheet to perform the dye

penetration test.

4.0

Apparatus

4.1

Magnaflux

Cleaner SKC-HF and penetrant SKL-HF and

suitable brush or roller for application. (See note below.)

4.2

Microscope

and suitable magnification device having a

reticle capable of measuring an area of 0.005 in. diameter.

5.0

Procedure

5.1 Cleaning

Clean the untreated side of the metal foil with

Magnaflux Spot Check Cleaner SKC-NF followed by a thor-

ough wiping action.

5.2

Dye Application

Apply

Magnaflux Penetrant SKL-HF

to the cleaned side of the metal.

5.3

Pinhole Evaluation

This

test is performed by counting

the number of dye spots on the treated side of the metal foil

which indicates passage of the dye penetrant through the

metal foil and measuring the size of pinholes.

6.0 Notes

The Magnaflux Chemicals may be obtained from

the Magnaflux Corporation, 7300 W. Lawrence Avenue,

Chicago, Illinois 60656.

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST METHODS MANUAL

Number

2.1.2

Subject

Pinhole

Evaluation, Dye Penetration Method

Date

3/76

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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