IPC-TM-650 EN 2022 试验方法.pdf - 第792页

velocity-change associated with the measured acceleration pulse is V. 5.1.3 The monitoring transducer shall be mounted on the test fixture immediately adjacent to the test specimen or dummy load. Two consecutive shock ap…

4.3 A circuit monitor capable of supplying a continuous cur-

rent of 100 milliamperes and of detecting discontinuities in this

current >1 microsecond.

5.0 Procedure

5.1 Calibration

5.1.1

The shock machine shall be set up to provide an

acceleration waveform conforming to Table I and Figure 3 or

4 as specified in the individual connector specification; if a

specific waveform is not specified, the terminal peak sawtooth

waveform shall be used.

5.1.2 The fixtured test sample or a suitable dummy load

shall be mounted on the shock machine during the calibration

procedure. Any dummy load shall have the same mass and

center of gravity as that of the test sample and shall be fix-

tured in a similar manner (a reject connector provides an ideal

dummy load).

For half-sine pulse of less than 3 milliseconds duration, it is

not required that the envelope fall within the tolerances speci-

fied in Figure 3. The faired (smoothed) amplitude of the mea-

sured pulse shall be within ± 20 percent of the ideal ampli-

tude. The measured duration shall be within ± 15 percent of

the specified duration. The velocity change of the faired pulse

shall be within ± 10% of the ideal change. The duration of the

pulse shall be measured at the 0.1A point on the pulse; the

base line duration of the pulse shall be calculated as the dura-

tion measured at the 0.1A point divided by 0.94. (For toler-

ance limits for measuring system frequency response see Fig-

ure 5.)

NOTE: The oscillogram should include a time about 3D long

with the pulse located approximately in the center. The inte-

gration to determine velocity change should extend from 0.4D

before the pulse to 0.1D beyond the pulse. The acceleration

amplitude of the ideal half sine pulse is A and its duration is D.

Any measured acceleration pulse which can be contained

between the broken line boundaries is a nominal half sine

pulse of nominal amplitude A and nominal duration D. The

IPC-3-8-1

Figure 1 Right Angle Connector Fixture (Suggested)

IPC-TM-650

Number

3.8

Subject

Mechanical Shock, Connectors

Date

7/75

Revision

Page2of5

velocity-change associated with the measured acceleration

pulse is V.

5.1.3 The monitoring transducer shall be mounted on the

test fixture immediately adjacent to the test specimen or

dummy load. Two consecutive shock applications to the cali-

bration load shall produce acceleration waveforms that fall

within the appropriate tolerance envelope; in addition, graphi-

cal integration of each recorded pulse shall indicate a velocity

change within 10% of the value specified in Table 1.

5.2 Test

5.2.1

The dummy load shall be replaced with the actual test

sample.

NOTE:

If all conditions, other than this substitution, remain

the same, the resulting test waveform shall be considered

satisfactory even though it may not conform to Figures 3 or 4,

as appropriate.

IPC-3-8-2

Figure 2 Parallel Connector Fixture (Suggested)

Table I

Test Conditions

Test

Condition

Peak

Acceleration

A-Gravity

Units

Nominal

Duration

D-Milli-

seconds Waveform

Velocity

Change

(G-MS)

A 50 11 Half-sine 350.30

B 75 6 Half-sine 286.62

C 100 6 Half-sine 382.16

D 500 1

Half-sine 318.47

E 1000 0.5

Half-sine 318.47

F 5000 0.5

Half-sine 477.70

G 50 10 Sawtooth 250.00

H 75 6 Sawtooth 225.00

I 100 6 Sawtooth 300.00

IPC-TM-650

Number

3.8

Subject

Mechanical Shock, Connectors

Date

7/75

Revision

Page3of5

5.2.2 The test sample shall be connected to the discontinu-

ity monitor and a minimum current of 100 milliamperes shall

be established in the series circuit comprising all contacts of

the test sample.

5.2.3 The test sample shall be subjected to three (3) shocks

in each direction along each of three (3) orthogonal axes (18

shocks total). During and after the application of each shock,

the contacts shall be monitored for discontinuities in excess of

1 microsecond.

NOTE:

The oscillogram should include a time about 3D long

with the pulse approximately in the center. The integration to

determine the velocity change should extend from 0.4D

before the pulse to 0.1D beyond the pulse. The peak accel-

eration,

magnitude of the sawtooth pulse is P and its duration is D.

Any measured acceleration pulse which can be contained

between the broken line boundaries is nominal terminal-peak

sawtooth pulse of nominal peak value, P, and nominal dura-

tion, D. The velocity-change associated with the measured

acceleration pulse is V.

6.0 Notes

6.1

Acceptance criteria shall be established in terms of one,

or any combination, of the following:

A. Loss of continuity during or after any imposed shock.

B. Mechanical damage,

IPC-3-8-3

Figure 3 Tolerances for Half Sine Shock Pulse

IPC-TM-650

Number

3.8

Subject

Mechanical Shock, Connectors

Date

7/75

Revision

Page4of5