IPC-TM-650 EN 2022 试验方法.pdf - 第625页

4.2 AC millivoltmeter capable of measuring true mvAC/rms having a resolution of 0.1 mv AC. The frequency response of the millivoltmeter shall be 20 Hz-to-20 Mhz. (MilliVac MV814A, Hewlett-Packard HP3400B, or equivalent).…

Scope

EOS

and electrostatic discharge (ESD) have been

proven to damage and degrade electronic components and

assemblies. This test method consists of a series of individual

test procedures to test soldering and desoldering hand tools

with grounded working surfaces for electrical grounds, tran-

sient voltages, and current leakage.

This series of test methods attempts to identify those bench-

top systems, which might contribute to premature assembly

failure from EOS/ESD related failure mechanisms. Test results

may be erroneous or skewed if they are incorrectly performed,

influenced by outside forces (e.g., air conditioning discharge

over the unit under test), or if incorrect test equipment is

selected.

Test equipment selected for equipment qualification must be

capable of measuring the low voltages and current emitted by

the unit under test (UUT). Additionally, the equipment must be

capable of reading pulses and frequencies emitted by the

UUT, which may be oscillator or microprocessor controlled.

As faster and more capable oscillator and microprocessor

controlled equipment is introduced by equipment manufactur-

ers, it may become necessary to select test equipment with a

broader bandwidth than that currently specified in this proce-

dure. Failure to do so is likely to qualify equipment that might

otherwise be disqualified.

Several of these tests can be falsely influenced by radio fre-

quency interference and electromagnetic interference from

lighting and equipment found in the workplace and testing

area. To avoid these influences the leakage and transient tests

should be performed in a screen room. In lieu of a screen

room, a separate test procedure (see Test Method 2.5.33.4)

has been provided to make a low cost shielded enclosure

which should provide adequate shielding for the performance

of these test procedures.

Warning:

These

are laboratory test procedures that may of

necessity expose terminals that carry line voltages. All stan-

dard laboratory safety procedures regarding the setup and

performance of tests with line voltage equipment must be

observed at all times.

Caution:

These

tests are performed with soldering systems

at their normal operating temperature. Test personnel must

take adequate precautionary steps to protect themselves and

others from potential burns.

1.1

Purpose

The

purpose of the electrical overstress (EOS)

test methods is to provide standardized test procedures for

the qualification of equipment to Appendix A of ANSI/J-STD-

001. Users may utilize Appendix A as part of an equipment

qualification procedure or may be referred to Appendix A

when the process has been determined to be out of control

(see ANSI/J-STD-001).

Applicable Documents.

ANSI/J-STD-001

Requirements

for Soldered Electrical and

Electronic Assemblies

IPC-TM-650 Test

Methods Manual

2.5.33.1 Measurement of Electrical Overstress of Hand Sol-

dering Tools - Ground Measurements

2.5.33.2 Measurement of Electrical Overstress of Hand Sol-

dering Tools - Transient Measurements

2.5.33.3 Measurement of Electrical Overstress of Hand Sol-

dering Tools - Current Leakage Measurements

2.5.33.4 Measurement of Electrical Overstress of Hand Sol-

dering Tools - Shielded Enclosure

Test Specimens

The

tests that make up this test

method call for the use of a locally produced sacrificial test

electrode. The test electrode shall be a piece of single or

double-sided 69 µm (15 mm thick) copper clad FR-4. The

electrode size shall be of a uniform size 45 mm x 23 mm ± 6.4

mm. The size may be adjusted to accommodate any locally

produced test fixtures.

The size of the electrode area is designed so that it is not so

big that it cools the temperature of the UUT below solder melt

and not so small that the temperature of the UUT causes

rapid oxidation or solder slagging. This electrode is designed

to be replaceable since it will deteriorate after repeated test-

ing.

Equipment/Apparatus

The

apparatuses utilized by the

procedures that make up this test method are given in 4.1

through 4.19.

4.1

Test

Electrode (see Section 3)

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.33

Subject

Measurement

of Electrical Overstress from

Soldering Hand Tools

Date

11/98

Revision

Originating Task Group

Manual Soldering Task Group (5-22c)

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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4.2

millivoltmeter capable of measuring true mvAC/rms

having a resolution of 0.1 mv AC. The frequency response of

the millivoltmeter shall be 20 Hz-to-20 Mhz. (MilliVac MV814A,

Hewlett-Packard HP3400B, or equivalent).

4.3

millivoltmeter capable of measuring at least 60 mv

DC and having a resolution of 1 mv DC

4.4 Ohmmeter

with a digital readout unit. It shall possess

scales that can measure resistances beyond 5 MΩ with an

accuracy of ± 100 KΩ or better (± 10% or better of the lower

limit). The ohmmeter shall have a resolution of 0.1 MΩ or

better.

4.5

Storage

oscilloscope, 100 Mhz bandwidth or faster, 1

MΩ input vertical amplifier

4.6 Oscilloscope

probe - X10 Attenuation

4.7

Constant

current Source capable of providing 10 milli-

amps DC

4.8

Resistor,

4.99 Ω, 1% precision

⁄

or greater (any com-

mercially available brand carbon or metal film)

4.9

Power

line filter, 20 ampere @ 115 VAC, 50 dB insertion

loss @ 5 Mhz/50Ω

4.10

Test

box (see 5.1)

4.11

Screen

room/shielded enclosure (optional) capable of

accommodating the entire UUT, cord, and hand piece. A fil-

tered AC power receptacle shall be available from within (see

Method 2.5.33.4).

4.12

Resistor,

1.00 KΩ, 1% (any commercially available

brand carbon or metal film)

4.13

Diodes

(two), which shall be of the lowest practicable

known forward bias devices. 1N34 diodes have been found

satisfactory for this purpose.

4.14

Receptacles (two)

4.15

Line

cord

4.16

Strain

relief

4.17 BNC

Connector

4.18

Edge

card connector w/mounting hardware

4.19

Metal

(bud) box

Procedure

All

the following test procedures should be

completed to ensure compliance with ANSI/J-STD-001:

Method 2.5.33.1 Measurement of Electrical Overstress

from Soldering Hand Tools—Ground

Measurements

Method 2.5.33.2 Measurement of Electrical Overstress

from Soldering Hand Tools—Transient

Measurements

Method 2.5.33.3 Measurement of Electrical Overstress

from Soldering Hand Tools—Current

Leakage Measurements

To construct a bench top shielded enclosure for use in lieu of

a screen room, refer to:

Method 2.5.33.4 Measurement of Electrical Overstress

from Soldering Hand Tools—Shielded

Enclosure

5.1

Test Box

Testing

has shown that for UUTs that utilize

high frequency circuits, layout and cord positioning can influ-

ence the AC current leakage reading. A compact configura-

tion such as the one shown in Figure 1 minimizes those influ-

ences (see Method 2.5.33.3).

6 Notes

6.1

Pass/Fail Limits for Transients and Steady-Sate

Voltage

EOS/ESD

papers typically discuss possible dam-

age to electronic components coming from electrostatic dis-

charge (ESD). The potentials discussed typically are 100’s and

1000’s of volts. This test method is also concerned with the

possible damage to electronic components coming from elec-

trical overstress (EOS). The EOS potentials of concern will be

1’s of volts down to millivolts. This test method strives to set

achievable EOS limits for soldering/desoldering equipment

based upon the ability to construct soldering equipment as

well as resolve small potentials from background interference.

Although any electronic component can be damaged by suf-

ficient amounts of EOS/ESD, conventional wisdom states that

semiconductors are the most susceptible. Two obvious EOS/

ESD caused failure modes in semiconductors are:

• Dielectric breakdown or reverse voltage breakdown due to

excessive potential

IPC-TM-650

Number

2.5.33

Subject

Measurement

of Electrical Overstress from Soldering Hand

Tools

Date

11/98

Revision

age2of5

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•

Junction overheated due to excessive forward current

6.2

Limits to Prevent Voltage Breakdown Due to Indi-

vidual Transients

integrated circuit geometries shrink,

dielectric breakdown voltage ratings also diminish. One semi-

conductor discussed here (battery operated integrated cir-

cuits) currently represents the lowest breakdown ratings.

S-MOS Systems’ SMC62L35 single-chip microcomputer is

designed to run from a single 1.5 volt battery. It has an abso-

lute maximum voltage (damage could result) of 2 volts.

The recommended limit for individual transients is 2 volts

peak.

6.3

Limits to Prevent Overheating Due to Steady-State

Leakage

Most

semiconductor junctions are intentionally

designed, but in integrated circuits, there are also unavoidable

intrinsic junctions. Also, there are junctions that are never sup-

posed to be operated in the forward direction (i.e., JFETs and

tuning diodes). The devices are not well character-ized by the

manufacturer regarding the maximum forward current.

Regardless of the nature of the junction, simultaneous forward

current and voltage drop results in power dissipation. If the

junction power results in a sufficient temperature increase, the

junction may be changed or destroyed. It is possible to pre-

vent forward current from flowing through a junction simply by

keeping the applied voltage below the forward junction volt-

age rating. Two semiconductors discussed here represent the

lowest forward junction voltage ratings: Schottky diodes and

germanium diodes. Motorola’s MBD201 Schottky diode and

most common germanium diodes begin to conduct at 220

millivolts. The test method apparatus represents these by

including commonly available 1N34 germanium diodes. To be

sure no junction heating can be caused by the UUT, the cur-

rent should be zero. But practically, since zero is difficult to

measure, a 1 microamp maximum tolerance can be permitted

without fear of overheating the junction. The recommended

limit for current leakage is 1 microamp (flowing through a

closed circuit, which includes parallel head-to-tail germanium

diodes).

IPC-2.5.33-1

Figure

1 Current Leakage Test Circuit Conﬁguration

AC RECEPT

ACLE

FOR VOLTMETER

AC RECEPTACLE

FOR UUT

BNC CONNECTOR

FOR VOLTMETER

TEST ELECTRODE

CARD EDGE

CONNECTOR

1K RESISTOR

METAL BOX

DIODES

GRN

BLK

WHT

IPC-TM-650

Number

2.5.33

Subject

Measurement

of Electrical Overstress from Soldering Hand

Tools

Date

11/98

Revision

age3of5

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