IPC-TM-650 EN 2022 试验方法.pdf - 第304页

1.0 Scope This method covers the measurement of bow and twist by maximum vertical displacement of an unre- strained panel of either cut to size panels or finished rigid printed boards including single- and double-sided, …

IPC-2422-7

Figure

7 Corners Supports

Supporting Jacks or Blocks

IPC-2422-8

Figure

8 Highest Point Measurement

Measure at

This Point

Measure at

This Point

IPC-TM-650

Number

2.4.22

Subject

Bow

and Twist (Percentage)

Date

6/99

Revision

age5of5

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1.0

Scope

This

method covers the measurement of bow

and twist by maximum vertical displacement of an unre-

strained panel of either cut to size panels or finished rigid

printed boards including single- and double-sided, multilayer,

and the rigid segments of rigid flex printed circuits. This test

method is only applicable to laminates greater than or equal to

0.5 mm [0.020 in] in thickness. This test method can also be

used after etching or after thermal stress with requirements as

agreed between user and vendor.

2.0

Applicable Documents

None

3.0 Test Specimen

The

test specimen for incoming

inspection shall be 300 x 300 mm ± 2mm[12x12in±0.08

in] in size. For smaller panel sizes and finished printed wiring

boards, use actual size. A minimum of three specimens is

required per sample, when evaluating pressed laminate

sheets.

4.0

Apparatus

4.1

Sample

Shear

4.2

Granite

Surface Plate or Equivalent

4.3

Feeler

Gauges or Equivalent

4.4

Micrometer

5.0

Test Procedure

5.1 Preparation of the Test Specimen

5.1.1

For

laminate sheet, the test specimens are to be cut

in such a fashion as to minimize mechanical flexing.

5.1.2

For

cut to size panels or printed wiring boards, use

actual size.

5.1.3

Mark

the specimen for traceability. No mechanical or

chemical pre-cleaning is permitted on the specimens.

5.2

Measurement of Bow and Twist

5.2.1

Place

the test panels on the surface plate such that

the maximum vertical displacement is observed. The panel

should be turned over in establishing the maximum vertical

displacement. The maximum vertical displacement may be a

corner or a side of the test specimen as illustrated in Figures

1 and 2.

5.2.2

Measure

the maximum vertical displacement by

inserting the feeler gauges between the surface plate and the

bottom surface of the laminate.

5.2.3

Verify

the thickness measurement by measuring the

total thickness of the feeler gauges with the micrometer.

5.2.4

Record

the maximum vertical displacement in 0.25

mm [0.01 in]. One value is recorded per test specimen. This is

the bow and twist of the test specimen.

IPC-24221-1

Figure

IPC-24221-2

Figure

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.4.22.1

Subject

Bow

and Twist—Laminate

Date

5/93

Revision

Originating Task Group

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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5.3

Calculation of Results

5.3.1 Average Bow and Twist Results

Bow and Twist =

Sum of the Measured Maximum

Vertical Displacements in mm [in]

Number

of Test Specimens

5.3.2

Maximum Bow and Twist Results

The

maximum

vertical displacement in mm [in] obtained for each lot of

material.

6.0 Notes

6.1

This

is the referee method; other methods of measure-

ment are allowable, if agreed upon between user and vendor.

IPC-TM-650

Number

2.4.22.1

Subject

Bow

and Twist—Laminate

Date

5/93

Revision

age2of2

电子技术应用　　　　　　　ｗｗｗ．ＣｈｉｎａＡＥＴ．ｃｏｍ