IPC-TM-650 EN 2022 试验方法.pdf - 第741页

6.0 Notes 6.1 Care should be exercised when interpreting analysis results. Cp may not be meaningful if the X-bar or R charts are out of control, or the process capability histogram is grossly non-normal. Consult IPC-PC-9…

Each

thermocouple shall be secured using positive mechani-

cal means. For example, the thermocouple wire could be

wound around a piano wire secured across the width of the

ager.

The natural airflow within the ager should be preserved. Extra

baffles or wire mesh screens should not be included for this

test, if not used during regular solderability testing. Venting

should be preserved as it is during normal testing.

The end of the thermocouple, including the weld bead and

exposed wires, should be oriented vertically (pointing upward)

to prevent water drops from collecting on them.

5.3

Performing the Test

Turn

on the ager and allow to

stabilize until measurement procedures used during regular

testing indicate stability has been achieved.

Note:

Four

hours is usually required in most agers to

achieve stability, and this ‘‘warmup’’ time should be

included in the production part test procedure.

Start the test, logging temperature every 15 minutes for 8

hours. (if the data clearly indicates that the natural variability

within the chamber varies more quickly, the sampling fre-

quency can be increased as necessary)

When logging temperatures, all thermocouples should be

measured simultaneously, or within 2 minutes maximum.

Temperatures shall be recorded in degrees Celsius. Measure

temperature to the nearest 0.1 degree.

The steam agers shall not be disturbed during the test, except

for routine maintenance or inspection procedures; as used

during normal testing. The ager shall be tested without other

components inside.

5.4

Test Conditions

Test

the temperature stability at the

temperature set point used for solderability testing.

5.5

Data Analysis

5.5.1

Record

the following data for each test.

a. Ager manufacturer and model number

b. Temperature indicator type, date of calibration

c. Test date

d. Sampling frequency

e. Total vent area on chamber lid [sq.cm]

f. Total chamber cross-sectional surface area [sq.cm]

g. Total volume of air in chamber [cu.cm]

h. Set point temperature

i. Test location

i. in hood

ii. on table against wall

iii. on table in open room

j. Location of room air conditioning vents (include sketch)

k. Notes on any special conditions during test

l. Distance from thermocouples to water level

m. Location of thermocouples inside ager (include sketch)

n. Room temperature when testing

5.5.2

Test Data

Prepare

a matrix of test data, showing

temperature of each thermocouple at each sampling interval.

5.5.3

Control Charts

Prepare

X-bar and R charts with

appropriate control limits. A control limit calculation form is

shown in Appendix 1. Further instructions on preparation of

control charts can be found in IPC-PC-90 or ANSI/ASQC

Z1.1, Z1.2, and Z1.3.

Subgroups shall consist of all thermocouples placed in the

ager (8 or 10), and which are measured simultaneously during

the test.

The charts shall be considered out of control if any of the fol-

lowing applies:

a. any one data point is beyond the control limits

b. any 2 or 3 consecutive points are near a control limit (outer

third)

c. a run of 8 or more points is above or below the center line

d. a run of 6 or more points is increasing or decreasing

5.5.4

Process Capability Histogram

Prepare

a process

capability histogram, using data ranges of 1/2°C or less.

Estimate the mean and standard deviation of the data.

5.5.5

Process Capability Index

Calculate

the process

capability index, Cp using the equation shown below (from

IPC-PC-90 example 7.5.6.2) for specification limits of ±1°C

[±1.8°F], ±2°C[±3.6°F], ±3°C[±5.4°F] and ±4°C[±7.2°F].

Cp = USL-LSL

Where,

= capability index

USL = upper specification limit

LSL = lower specification limit

S = process standard deviation

Include a plot of Cp against specification tolerance range.

IPC-TM-650

Number

2.6.23

Subject

Test

Procedure for Steam Ager Temperature Repeatability

Date

7/93

Revision

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6.0

Notes

6.1

Care

should be exercised when interpreting analysis

results. Cp may not be meaningful if the X-bar or R charts are

out of control, or the process capability histogram is grossly

non-normal. Consult IPC-PC-90 or ANSI/ASQC Z1.1, Z1.2

and Z1.3 for further details.

IPC-TM-650

Number

2.6.23

Subject

Test

Procedure for Steam Ager Temperature Repeatability

Date

7/93

Revision

age3of3

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Scope

The

purpose of these tests is to characterize

changes in individual interconnection resistances as a function

of exposure time in various environmental aging conditions for

both flex to PWB and flex to indium-tin-oxide (ITO) coated

glass bonds.

Applicable Documents

IPC-3408

General

Requirements for Anisotropically Conduc-

tive Adhesive Films

Test Specimens

3.1

0.2

mm line/space test boards

0.2 mm line/space flex test circuits

Apparatus

4.1

ITO

coated soda-lime glass test slides, 20 ohms/sq. mm

4.2

Polypropylene

trays for sample storage in chamber

4.3

Instrumentation

to permit four-probe resistance mea-

surement

4.5

Required

environmental test chamber(s):

a) Thermal aging,

100°C

b) Thermal cycling,

-55°C to >125°C,

five hour period

c) Humidity aging,

60°C/95% RH

Procedure

5.1 Sample Preparation

5.1.1

Cut

the flex test circuits to the appropriate length (see

Figure 1 and Figure 2). If flex board samples are being pre-

pared, all traces on the flex should be shorted together on one

end.

5.1.2

Use

of new PCB is recommended. If new boards are

being used, there should be no need for any special cleaning

procedure. If used boards are to be used, they should be

inspected to ensure that:

a) Protective metalization (Au or Pb-Sn) is intact.

b) FR-4 isn’t significantly discolored from prior high tempera-

ture exposure.

c) The board is free of any residue from previous tests.

5.1.3

Refer

to 5.2 for proper bonding procedure.

5.2

Sample Procedure

5.2.1

Prepare

at least three test samples for each test con-

dition to be run. For the flex board case, it is possible to

mount two test samples on each board. Refer to IPC-3408 for

proper bonding procedure.

5.2.2

After

bonding is completed, each sample should be

identified by a test number. Test numbers should be written

on the test substrate using an indelible marker.

5.2.3 Clamp

the unbonded end of the flexible circuit to the

matching board traces to make electrical contact, with an

elastomeric compliant layer behind the flex to maintain uniform

contact force.

5.2.4

Initial

interconnection resistances should be measured

and recorded. The recommended measurement technique is

illustrated in Figure 3. This technique can be used with either

test sample type.

Note:

This

technique doesn’t allow for the measurement of

the first and last circuit trace. There are 15 measurements to

be made on each sample.

5.2.5

Samples

should be placed in the polypropylene trays,

and the trays placed in the appropriate chamber. The time

and date should be noted for the purpose of computing

elapsed time.

5.2.6

Samples

should be removed from the chambers for

resistance measurement after 24-hour, one-week, three-

week, and six-week time points. All environmental tests are

considered complete after six weeks. Samples should be

allowed to equilibrate at ambient conditions for at least 30

minutes prior to measurement.

5.2.7

All

resistance data should be tabulated and/or graphed

to facilitate proper interpretation of the results.

2215

Sanders Road

Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.6.24

Subject

Junction

Stability Under Environmental Conditions

Date

11/98

Revision

Originating Task Group

SMT Mounting Adhesives Task Group (5-24d)

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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