IPC-TM-650 EN 2022 试验方法.pdf - 第635页

and control motor-pumps and solenoids. To facilitate observ- ing or capturing a transient event, the UUT should be oper- ated in such a manner where switching takes place. The UUT should be brought to a state where heate…

air

solenoid by actuating the UUT’s finger switch or foot

switch. Repeat these operations, fine-adjusting the oscillo-

scope for best display of any transient peaks for a minimum

of three measurable trials.

5.3

Calculation and Interpretation of Results

Record

the

peak amplitude (see Figure 3). All three measurement tri-

als must have peak voltages ≤ 2.0 volts.

The peak voltage shall be ≤ ± 2.0 volts.

6 Notes

tracking test results, record the measured values

on a copy of the form found in Method 2.5.33.

6.1

Oscilloscope Adjustments

good initial setup for the

oscilloscope was found to be as shown in Table 1.

It’s important to start from a position of low trigger sensitivity

and work toward high sensitivity. If one were to start with high

sensitivity, weak transients would trigger the oscilloscope

before the strong, more potentially damaging ones.

6.2

Discussion of Transients.

Transients

are generated

by voltage or current switching in the UUT. Switching typically

occurs in circuits that modulate heaters, drive LED displays,

IPC-2.5.33.2-2

Figure

2 Alternate Apparatus for Transient Measurement

AC POWER

BULKHEAD

LINE

FIL

TER

JUNCTION BOX

WITH RECEPTACLE

1 MEGAOHM

INPUT

OSCILLOSCOPE

SHIELDED ENCLOSURE

UNIT

UNDER TEST

TEST

ELECTRODE

GROUND

CLIP

ELECTRODE

BULKHEAD

10 MEGAOHM

(X10) SCOPE

PROBE

IPC-2.5.33.2-3

Figure

3 Transient Waveform Measurement

VPEAK

IPC-TM-650

Number

2.5.33.2

Subject

Measurement

of Electrical Overstress from Soldering Hand

Tools - Transient Measurements

Date

11/98

Revision

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and

control motor-pumps and solenoids. To facilitate observ-

ing or capturing a transient event, the UUT should be oper-

ated in such a manner where switching takes place. The UUT

should be brought to a state where heater power is cycling

off-and-on. Heaters that are running at 100% duty cycle (con-

stantly on) may not generate any measurable transients. For

UUTs that incorporate relays, solenoids, or motors the UUT’s

functions should also be operated in such a manner where

these devices energize and de-energize.

As the UUT is cycled, the oscilloscope’s trigger should be

adjusted to a more sensitive setting until a transient causes a

trigger. The event may have to be repeated as the oscillo-

scope’s storage controls are re-adjusted for best picture.

Sometimes the event has a peak amplitude better observed

on a different vertical scale.

able 1 Oscilloscope Setup

ertical 500 mv/div. DC coupling

Horizontal 100 ns/div.

Trigger Source

Level

Mode

Internal

Full cw or ccw rotation

(large peaks cause trigger)

single sweep

Polarity + or -

Storage (for analog scopes) fast

variable persistence

auto erase

IPC-TM-650

Number

2.5.33.2

Subject

Measurement

of Electrical Overstress from Soldering Hand

Tools - Transient Measurements

Date

11/98

Revision

age4of4

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Scope

This

test method measures DC and AC current

leakage from the tip of the Unit Under Test (UUT) to ground.

The AC frequency range measured is in the 20 Hz to 20 MHz

range, which covers the currently known equipment base. If

soldering systems with oscillator or microprocessor frequen-

cies higher than 20 Mhz are to be qualified, then wider band

width measuring equipment should be considered. Failure to

do so is likely to qualify equipment that might otherwise be

disqualified.

There are three times when current leakage measurements

should be done:

• Equipment qualification for purchase

• Incoming inspection of new or repaired equipment

• Process monitoring (periodic checks)

Current leakage is measured and indicated by measuring the

voltage developed across a resistor, which closes the circuit

between the tip of the UUT and ground. DC and true rms AC

measurements will be made separately.

This test may be falsely influenced by radio frequency interfer-

ence and electromagnetic interference from lighting and

equipment found in the workplace and testing area. At a mini-

mum, shielded test leads should be utilized. To avoid these

influences it may be necessary to perform the leakage and

transient tests in a screen room. In lieu of a screen room, a

separate test procedure (see Method 2.5.33.4) has been pro-

vided 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.

Applicable Documents

ANSI/J-STD-001

Requirements

for Soldered Electrical and

Electronic Assemblies

IPC-TM-650 Test

Methods Manual

2.5.33 Measurement of Electrical Overstress from Solder-

ing Hand Tools

2.5.33.4 Measurement of Electrical Overstress from Solder-

ing Hand Tools - Shielded Enclosure

Test Specimens

Test

specimens for this procedure are

detailed in Method 2.5.33.

Equipment/Apparatus

The

apparatus, materials, and

preparation of apparatus and materials used to perform this

test shall be as stated in 4.1 through 4.7.

4.1

Test

Electrode (see Section 3)

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

Test

box (see Section 6)

4.5

Optional

4.5.1

Storage

oscilloscope, (with rms math function), 100

Mhz bandwidth or faster, 1 MΩ input vertical amplifier

4.5.2

Oscilloscope

probe - X10 attenuation

4.5.3

Screen

room/shielded enclosure - capable of accom-

modating the entire UUT, cord, and handpiece. A filtered AC

power receptacle shall be available from within (see Method

2.5.33.4).

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062

IPC-TM-650

TEST

METHODS MANUAL

Number

2.5.33.3

Subject

Measurement

of Electrical Overstress from

Soldering Hand Tools - Current Leakage

Measurements

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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