IPC-TM-650 EN 2022 试验方法.pdf - 第740页

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…

1.0

Scope

This

test procedure measures the temperature

repeatability inside steam agers used to condition compo-

nents prior to solderability testing. It should be applied at

installation and after any modification to the equipment and/or

its location.

2.0

Applicable Documents

IPC-PC-90

General Requirements for Implementation

of Statistical Control

MIL-STD-202 Test methods for Electronics and Electrical

Components Parts

MIL-STD-750 Test Methods for Semiconductor Devices

MIL-STD-883 Test Methods of Microelectronics

MIL-STD-45662 Calibration Systems Requirements

ANSI/ASQC Z1.1 Guide for Quality Control Charts

ANSI/ASQC Z1.2 Control Chart Method of Analyzing Data

ANSI/ASQC Z1.3 Control Chart Method of Controlling Quality

During Production

ANSI/J-STD-002 Solderability Tests for Components Leads,

Terminations, Lugs, Terminals and Wires

3.0

Test Specimens

None

required

4.0

Apparatus

The

following test equipment shall be used

during the tests:

4.1

Type

T copper-constantan thermocouple wire, 24 AWG,

±0.5°C[±0.09°F] accuracy minimum, premium grade.

Note:

PTFE

insulation is preferred.

4.2 Thermocouple

Temperature Indicator, with an accuracy

of ±0.5°C[±0.9°F] minimum, with capability for type T thermo-

couples, and be calibrated in accordance with MIL-STD-

45662 or the equivalent.

It is recommended that the thermocouple indicator have

capability to log data and be able to take all readings within 2

minutes.

Since readings must be taken periodically, it is recommended

that the indicator have capability for pre-settable time delay

between measurements.

Note:

Although

the specific equipment used to develop this

method was as specified above, other thermocouple types

and temperature indicators may be used provided the require-

ments of 5.1 are met.

4.3

Hot

plate with 500 ml glass beaker

4.4

The

steam ager as used to perform component solder-

ability testing per MIL-STD-202, Method 208; MIL-STD-883,

Method 2003; or MIL-STD-750, Method 2026; or ANSI/J-

STD-002 as applicable.

5.0

Test Procedure

5.1 Thermocouple Calibration

All

thermocouples to be

used during the steam ager test shall first be checked.

Loosely bundle the thermocouples and place in a 500 ml

glass beaker of vigorously boiling water, heated by a hot plate.

Measure the temperature indicated by each thermocouple. All

thermocouples should indicate the same temperature ±0.5°C

[±0.9°F] to the local boiling point of water. If any thermocouple

differs by more this amount, the weld bead shall be reworked

(and all thermocouples reverified), or the thermocouple shall

be discarded for the purpose of this test.

5.2

Install Thermocouples

Install

the thermocouples in

the ager at the component level. All thermocouple weld beads

shall be at the same height ±6.35 mm [±0.25 in]. The distance

from the weld to the water shall be measured prior to the test.

All thermocouples shall be at least 25.4 mm [1 in] away from

any wall or bulkhead. The thermocouples should be distrib-

uted evenly around the normal working area inside the ager,

and the location shall be recorded. Ten thermocouples shall

be used in larger agers, eight in smaller agers. For example, if

the ager uses five small drawers, a thermocouple centered in

the front and back halves of the drawer would be sufficient. If

no drawers are used, the thermocouples should be distrib-

uted around the areas where parts are usually placed.

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.6.23

Subject

Test

Procedure for Steam Ager Temperature

Repeatability

Date

7/93

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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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

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