IPC-TM-650 EN 2022 试验方法--.pdf - 第53页

4.17 Diamond polishing abrasive (6.0 - 1.0 µm [236 - 39.4 µin]). 4.18 Polishing lubricant. 4.19 Specimen etching solution (see 5.5.2.1). 4.20 Cotton balls and swabs for cleaning and etchant appli- cation. 4.21 Isopropyl …

1 Scope

This method is to be used as a guideline for pre-

paring a metallographic specimen of printed boards. The fin-

ished microsection is used for evaluating the quality of the

laminate system and plated structures (plated-through holes,

solder joints, vias, etc.). The plated structures can be evalu-

ated for characteristics of the copper foils, plating, and/or

coatings to determine compliance with applicable perfor-

mance specification requirements.

Metallographic sample preparation is regarded by many as

essentially a highly developed skill; this method describes

those techniques that have been found to be generally

acceptable. It does not attempt to be so specific as to not

allow acceptable variations that can differentiate metallogra-

phers. Furthermore, the success of these techniques remains

highly dependent upon the skill of the individual metallogra-

pher.

Note: These microsection techniques are processes and are

intended as guidelines and thus variations are allowed.

Note: The use of the materials listed in Section 4 may be lim-

ited or forbidden in some environments. Please review the

Safety Data Sheet (SDS) for the materials being used.

1.1 Method A (Manual) Description

Manual metallo-

graphic preparation of sample(s).

1.2 Method B (Semi or Automatic) Description

Semi or

automatic metallographic preparation utilizing dedicated

microsection equipment to prepare multiple samples.

2 Applicable Documents

IPC-MS-810

Guidelines for High Volume Microsectioning

ASTM E 3

Standard Methods of Preparation of Metallo-

graphic Specimens

3 Test Specimens

A test coupon or printed board to be

inspected per the applicable performance specification, which

includes the features to be evaluated (i.e., plated holes or

laminate). This may require multiple microsections.

4 Apparatus or Material

4.1

Sample removal method (see IPC-MS-810 for the best

method to meet your needs).

4.2

Personal Protective Equipment (e.g., eye protection,

gloves)

4.3

Ventilation system (Fume Hood) in compliance with

material SDS (as required)

4.4

Mount molds.

4.5

Smooth, flat mounting surface.

4.6

Release agent (optional).

4.7

Sample supports (optional for Method A).

4.8

Sample alignment tools (Method B).

4.9

Metallographic wet grinding/polishing system or equip-

ment (as applicable).

4.10

Low magnification visual aid (reticle optional)

4.11

Metallographic microscope capable of minimum con-

struction integrity magnifications as specified in procurement

documentation.

4.12

Vacuum pump and desiccator or pressure pot

(optional).

4.13

Potting material (maximum cure temperature 93 °C

[200 °F]). (For discussion on selection of potting material refer

to IPC-MS-810.)

4.14

Sandpaper. Federation of European Producers of

Abrasives (FEPA)(ISO 6344) paper backed Silicon Carbide P

(coated) abrasive medium P80-P4000 (United States CAMI

(Coated Abrasive Manufacturers Institute) grit range: 80-1200.

4.15

Polishing Cloths. A hard, low, or no nap cloth for rough

and intermediate polishing, and a soft, woven, or medium nap

cloth for final polishing.

4.16

Oxide or colloidal silica polishing suspension (final pol-

ish, 0.3 - 0.04 µm [11.8 - 1.57 µin]). (Optional).

3000 Lakeside Drive, Suite 105N

Bannockburn, IL 60015-1249

IPC-TM-650

TEST METHODS MANUAL

Number

2.1.1

Subject

Microsectioning, Manual and Semi or Automatic

Method

Date

6/15

Revision

Originating Task Group

Microsection Subcommittee (7-12)

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.

Page 1 of 8

Association

Connecting

Electronics

Industries

4.17

Diamond polishing abrasive (6.0 - 1.0 µm [236 - 39.4

µin]).

4.18

Polishing lubricant.

4.19

Specimen etching solution (see 5.5.2.1).

4.20

Cotton balls and swabs for cleaning and etchant appli-

cation.

4.21

Isopropyl alcohol, 25% methanol aqueous solution, or

other suitable solvent (check for reaction with the encapsula-

tion media and marking system).

4.22

Permanent identification marking method (e.g., laser

scribing, permanent marker, embedded label, etc.) to provide

traceability.

4.23

Ultrasonic cleaner (optional).

5 Procedure

The procedure steps of this section are

applicable to both Method A and Method B unless otherwise

indicated.

5.1 Removal of Specimen

Remove the required speci-

men(s) from the product to be tested. Allow sufficient clear-

ance to prevent damage to the area to be examined. Some

commonly used methods include sawing using a jewelers

saw, miniature band saw, diamond saw or abrasive cut-off

wheel; routing using a small milling machine; or punching

using a sharp, hollow die (not recommended for thick or brittle

materials, i.e., polyimide and some modified epoxy resin sys-

tems) (see IPC-MS-810). All samples must maintain required

traceability.

5.2 Preparation of Specimen

Note: Complete any required preconditioning and/or stress

testing prior to mounting.

Note: To determine correct plane of grind for plated struc-

tures with a length of 0.010 inch or less, the diameter of the

structure shall be required for the assessment. For microvias

the diameter of the structure at the capture land layer shall be

provided. For stacked structures where both structures do not

meet center of hole tolerance at the same time, refer to the

performance specification for guidance or AABUS.

5.2.1 Method A

Deburr all edges prior to mounting using

rough grind grit in accordance with Table 5-1 to within

approximately 1.27 mm [0.05 in] of final polish depth. Ensure

that the evaluation edge is parallel to the mounting surface

and the sample maintains perpendicularity as shown in Figure

5-1.

5.2.2 Method B

Remove the specimen from the printed

board or panel such that the tooling pin holes or target PTHs

are not damaged.

5.2.2.1 Inspect Tooling Pin System

Inspect the tooling

pin holes or slots to verify they are not plugged or damaged.

Clear plugged tooling pin holes with a tool that will not change

its dimensional location or enlarge the hole. A drill bit of the

same hole diameter is recommended.

Inspect the tooling pins for foreign material adhering to them.

Clean the pin surface as required. Discard any pins that are

bent or the surface scarred.

5.3 Mounting Metallographic Sample

5.3.1

Clean mount molds and mounting surface and dry

thoroughly. Apply release agent (Optional).

5.3.2

Thoroughly clean the sample using a suitable solvent

such as isopropyl or ethyl alcohol. This is especially important

when flux or oil is present as it may result in poor adhesion of

the potting material causing gaps between the specimen and

the material. These gaps make proper metallographic sample

preparation extremely difficult, if not impossible.

5.3.3 Loading the Specimen

5.3.3.1 Method A

Stand specimen in mount mold, perpen-

dicular to the base using sample supports, clips, or with the

IPC-221-5-1

Figure 5-1 Maintaining Perpendicularity throughout the

Microsection Process

90º

NOT PERPENDICULAR PERPENDICULAR

IPC-TM-650

Number

2.1.1

Subject

Microsectioning, Manual and Semi or Automatic Method

Date

6/15

Revision

Page 2 of 8

000

use of double-sided adhesive tape. Keep sample in center of

mount mold.

5.3.3.2 Method B

Load specimen on tooling pins. The pins

align the target PTHs on a common plane. This common

plane assures all the PTHs will grind to the center of the hole

at the same instance.

Push the tooling pins into the tooling holes or slots. The pins

must fit snugly.

5.3.4 Preparing Potting Material

Personal protection is

recommended to prevent skin sensitization. Prepare potting

material to ensure cure temperature does not exceed 93 °C

[200 °F]. Mix by folding the potting material in such a way so

as to minimize air bubbles.

5.3.5 Pouring Potting Material

Fill the mount mold care-

fully with potting material, by pouring from one side to ensure

adhesion to all sample surfaces.

5.3.5.1 Method A

The sample must remain upright while

pouring.

5.3.5.2 Method B

Assure the tooling pins do not shift

position or rise up while pouring and/or curing of the potting

material.

5.3.6 Removal of Vacuum or Pressure for Potting Mate-

rials

While in a liquid state, potting materials may require

vacuum or pressure in order to achieve proper encapsulation.

Remove vacuum or pressure prior to cure to prevent undue

stress on the specimen.

5.3.7 Cure and Mount Removal

Allow specimen to cure

and cool to room temperature before removing hardened

mount from mount mold. The minimum qualities the mount

should exhibit are:

• The potting material is hard and not tacky.

• Minimal bubbles in the potting material.

• No gaps between the potting material and the sample.

• All gaps in structure to be evaluated should be filled with

potting material.

The presence of these deficiencies will result in sample prepa-

ration difficulties, as noted in 5.3.2.

5.3.8 Marking of Specimen

Identify the specimen by a

permanent method (see 4.22). The selected marking system

should remain unaffected by subsequent processing.

5.3.9 Mount Preparation

5.3.9.1 Method A

Remove sharp edges and flatten top

with low grit (240) sand paper.

5.3.9.2 Method B

Remove the excess mounting material

from the exposed ends of pins.

5.4 Grinding and Polishing

The following is a description

of the basic grinding and polishing steps. Other methods may

be required by contract. See Table 5-1 for examples of 2, 3,

4, and 5-step methods for Method A and Table 5-2 and Table

5-3 for Method B.

The minimum qualities the mount shall exhibit are:

1) The grinding and polishing accuracy of the microsection

shall be such that the viewing area of each of the PTHs is

within 10% of the drilled diameter of the hole as shown in

Figure 5-2.

2) Only fine grind scratches apparent on the mount when

viewed at 100X magnification.

3) Little or no gap between the potting material and the

specimen(s).

4) No residual abrasive paper grit material on the mount

surface.

5) The ground surface has only one plane of material removal.

If the mount has several planes of material removal, por-

tions of the sample will not polish since the odd surface

never touches the polishing cloth.

Note: Ultrasonic cleaning is highly recommended, especially

between the finer grinding steps, prior to rough polishing and

between all polishing steps. It is the nature of printed board

specimens, especially those with epoxy base material follow-

ing thermal exposures, to contain voids that can trap grinding

and polishing residues that are not removed during simple

rinsing. Care needs to be exercised not to damage the speci-

men surface with excessive ultrasonic cleaning. Specimen

sample can be placed with the polished surface perpendicu-

lar to the bottom of the vessel. Ultrasonic cleaning for as little

as one minute can damage a polished surface.

IPC-TM-650

Number

2.1.1

Subject

Microsectioning, Manual and Semi or Automatic Method

Date

6/15

Revision

Page 3 of 8