IPC-TM-650 EN 2022 试验方法--.pdf - 第403页

5.3.2 If there is a metal heat spreader on the BGA, it must be left in place until after the dye-drying step (5.11). 5.4 Section out the desired component area l eaving about 19 mm to 38 mm [0.75 in to 1.5 in] of board a…

Figure 15 Test Fixture Construction, Older Design

IPC-TM-650

Page 23 of 25

50.11

]

Dim

”B”

—

76.76

73.58

72.67

69.49

66.32

17.75

14.58

6.65

3.48

3.05

hole,

places

Drill

tap

for

#4-40

screw,

places

Drill

tap

for

#1-72

screw,

places

17.75

v—

14.58

!■*—

6.65

•-

548

—

1.40

—

6.35

DETAIL

aluminum

one

req'd

26.64—

10.44

—

7.26

——

—

4.09

—

3.17

—

Nate:

Specimen

nominal

thickness

1.27

1.57

Dimension

"A"

for

base

plate

4.78

5.08

Dimension

"A"

for

base

plate

4.47

4.78

K3F

mrn

17.75

14.58

17.75

14.58

6.65

3.48

3.05

hole,

places

DETAIL

aluminum

one

req'd

Drill

3.05

countersink

for

screw,

places

Drill

2.06

countersink

for

screw,

places

—

76.76

一

73.58

72.67

69.49

66.32

—

50.11

26.64

10.44

7.26

——

4.09

—

3.17

6.65

3.48

二

及

=K5F

册

1.40

6.35

PC-2555-15

Number

2.5.5.5

Subject

Stripline

Test

for

Permittivity

and

Loss

Tangent

(Dielectric

Constant

and

Dissipation

Factor)

X-Band

Date

3/98

Revision

r-TTHn

29.0

996L

R7Z

5.3.2

If there is a metal heat spreader on the BGA, it must

be left in place until after the dye-drying step (5.11).

5.4

Section out the desired component area leaving about

19 mm to 38 mm [0.75 in to 1.5 in] of board around the part.

If the board is small enough to fit the pull fixture, leave the

board intact.

5.4.1

A diamond sectioning saw is recommended to per-

form this step. Other sectioning equipment (e.g., diamond

saw, milling tool, water jet, etc.) can be used if it does not

induce stress on the sample area.

5.5

A detailed visual examination under stereomicroscope is

required at this stage. If needed, clean the sectioned part with

only water and compressed air. It is important to not use sol-

vent for this step.

5.5.1

A thorough visual examination can detect signs of

mechanical damage/stress, which are indicated by fractured/

broken-up flux around the SMT solder joint (see Figure 1 and

Figure 2).

5.5.2

If the SMT part utilizes corner-applied adhesive which

was not easily visible before, examine it now. Document the

glue coverage per IPC-7095 or as determined between the

lab and the customer.

5.5.3

Document the findings in lab notes and with photos.

5.6

Clean any flux residue from around the SMT solder joints

using the appropriate flux remover.

Isopropyl alcohol is not acceptable due to its inability to

dissolve flux.

5.6.1

The sectioned part/board area should be submerged

in liquid flux remover for at least one hour. The goal is to fully

remove the flux residue. The exact amount of time the part/

board is submerged depends on the sample conditions.

5.6.1.1

Approximately two to three times during soak, gen-

tly swirl the beaker containing the sectioned part for at least

20 seconds. This will aid the flux solvent in removing the flux

ring residue.

5.6.2

Reworked samples may require additional time in the

liquid flux remover.

5.6.3

Examine the sample under a microscope to determine

if additional time is needed to remove the flux ring.

5.6.4

After using the liquid flux remover, use a spray can flux

remover to thoroughly flush all four sides of the component.

5.6.4.1

Removing all flux residues and other particles/oils

enables the dye to penetrate the fractures.

5.6.4.2

Failure to completely remove the flux from around

the solder joint will prevent dye penetration and give false indi-

cations of a good solder joint.

5.7

Use low-pressure compressed air to blow off excess flux

solvent.

5.7.1

If desired, perform a final rinse with isopropyl alcohol

or acetone at this time.

5.8

Pour the dye into a small tray until the sectioned sample

is completely immersed in the dye.

5.8.1

If dye is being reused, ensure it has sufficient viscos-

ity. Viscosity is critical to the ability of the dye to penetrate into

cracks within the parts being dyed. If there are any concerns

with dye viscosity, discard the old dye and use fresh, new

dye.

5.9

Place the tray containing the sectioned sample into a

vacuum chamber.

5.9.1

Draw a 67.7 kPa [20 in Hg] vacuum for three to four

minutes.

5.9.2

Partially vent and then reapply vacuum to the chamber

to aid in dye penetration.

5.9.3

Leave the part submerged in dye for a minimum of 30

minutes with a constant vacuum of 67.7 kPa [20 in Hg].

5.9.3.1

Do not exceed 67.7 kPa [20 in Hg] of vacuum at any

time, or the dye will start to boil off.

5.10

Vent the vacuum chamber slowly and remove the

sample from the tray.

5.10.1

Allow the excess dye to drain off the sample.

Number

2.4.53

Subject

Dye and Pull Test Method (Formerly Known as Dye and Pry)

Date

8/2017

Revision

Page 2 of 11

IPC-TM-650

Note:

5.10.2

Use low-pressure compressed or canned air to gen-

tly flush any remaining dye from under the part until no further

dye runs out.

5.10.3

Dry the sample in an oven, not to exceed 100 °C or

as appropriate for the sample. If possible, allow the part to dry

overnight at ambient conditions. Wet dye can smear during

component separation, resulting in false conclusions.

5.11

Remove the sectioned part from the oven and allow it

to cool.

5.12

Perform the pull operation to physically/mechanically

remove the part from the board.

5.12.1

Abrade the surface to allow for an improved bonding

of the structural adhesive.

One way to perform this is to use a small piece of

coarse-grit sandpaper to lightly sand and roughen the part top

surface. This will remove the dried dye and will allow the top

surface to bond with the anchored tee nut.

5.12.2

Bond the tee nut to the top of the part using struc-

tural adhesive. Allow the structural adhesive to cure.

5.12.3

Use a pull-test fixture with a uniform tensile force to

separate the part from the board.

5.13

Examine the board and component for dye indications.

If necessary, gently dust with canned air or dry, filtered and

regulated compressed air to the separated part to clear away

pull debris (flakes of dye, solder mask, etc.).

5.13.1

Any fractured interface that was present will be

stained with dye. Usually, both sides are stained in a common

(mirrored) pattern.

5.14

Take photos of dyed regions and plot results as agreed

upon between the lab and the customer.

5.15 Test Report

Include the following (or as agreed upon

between the lab and the customer):

• Initial visual observations (see 5.2 and 5.5)

• Dyed interface separation location

• If required, dye indication amount/percentage (acceptability

criteria to be determined between laboratory and customer)

Other items that can be included in the test report include:

• Mapping of all separation locations

6 Notes/Figures

The figures in this section are included for informational pur-

poses only. They do not depict a correct or incorrect method

for conducting this test method.

Number

2.4.53

Subject

Dye and Pull Test Method (Formerly Known as Dye and Pry)

Date

8/2017

Revision

Page 3 of 11

IPC-TM-650

Example:

Figure

Ball

Grid

Array

(BGA)

With

Disturbed

Flux,

Indicating

Possible

Solder

Laminate

Fractures

Figure

Ball

Grid

Array

(BGA)

Without

Disturbed

Flux