IPC-TM-650 EN 2022 试验方法.pdf - 第707页

1.0 Scope The purpose of this test method is to provide a consistent procedure to test the sensitivity of electronic com- ponents to ultrasonic energy. There has been reluctance in the electronics industry to use ultraso…

Ultrasonic

Test Data Record

Name

of tester

Date

Company

Address

Phone Fax

Make

and model of equipment

ank size

Dimensions

(cm cm x cm)

Generator

output power

Frequency

(KHz)

No.

of boards tested per trial

Substrate

Exposure

time

Other

stress testing (pre- or post-)

Describe

Component

tested No. tested Passed Failed Comments

Type Mfgr Part #

Mail

to: IPC Fax to: 847-509-9798

2215 Sanders Road

Northbrook, IL 60062-6135

Attn: Ultrasonic Cleaning Task Group

IPC-TM-650

Number

2.6.9.1

Subject

Test

to Determine Sensitivity of Electronic Assemblies to

Ultrasonic Energy

Date

1/95

Revision

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1.0

Scope

The

purpose of this test method is to provide a

consistent procedure to test the sensitivity of electronic com-

ponents to ultrasonic energy. There has been reluctance in

the electronics industry to use ultrasonic energy for printed

board assembly cleaning because of the possibility of damage

to wire bonds in active, hermetically sealed components or

other damage that might cause latent failures.

Recent work has shown that electronic components have a

low potential for damage from ultrasonics (References 1-7)

under conditions seen in most cleaning processes. In addi-

tion, MIL-STD-2000 Rev. A and J-STD-001 now allow for the

use of ultrasonic cleaning, as does the proposal for IEC TC91

International Standards based on an updated revision of the

J-STD-001.

1.1

Definitions

Ultrasound:

All

sound in frequencies above the range of

human hearing. For the purpose of ultrasonic cleaning, fre-

quencies between 18-800 KHz are in commercial use. In the

lower frequency ranges, fluid cavitation is the primary agitation

method. In the higher frequency ranges, microstreaming

(i.e., fluid pumping) is believed to be the form of mechanical

agitation.

Frequency:

The

number of periodic oscillations, vibrations of

waves per unit of time, usually expressed in cycles per second

(Hertz).

Generator:

electronic system which converts the 50 or 60

Hz power line electricity into an ultrasonic frequency drive sig-

nal which powers the transducers in their resonant frequency

range.

ransducers:

Convert

electrical energy from the generator into

mechanical (vibratory) energy, producing high intensity sound

waves in a liquid and causing cavitation of microstreaming.

Transducers are primarily of two types, piezoelectric and mag-

netostrictive.

Piezoelectric:

Piezoelectric

ceramics, which change dimen-

sions in the presence of an electric field. Thickness varies in

response to an applied voltage. Conversion efficiency =

70-90%.

Magnetostrictive:

Made

of nickel or its alloys, it changes length

when placed in a magnetic field. Conversion efficiency =

20-50%.

Cavitation:

The

rapid formation and oscillation or violent col-

lapse of microscopic bubbles or cavities in a liquid, produced

by introducing high frequency (ultrasonic) sound waves into a

liquid. The agitation from countless implosions of these

bubbles create a highly effective scrubbing of both exposed

and hidden surfaces of parts immersed in the cleaning solu-

tion.

Degas:

The

act of removing entrained gas from cleaning fluid.

Gas bubbles tend to absorb ultrasonic energy, thereby

decreasing the amount of energy available for cleaning.

Power

Density:

Average

output power of ultrasonic generator

divided by total volume of liquid being sonified.

2.0

Applicable Documents

2.1 Institute for Interconnecting and Packaging Elec-

tronic Circuits (IPC)

IPC-T-50

Terms

and Definitions for Interconnecting and

Packaging Electronic Assemblies

IPC-CH-65

Guidelines

for Cleaning of Printed Boards and

Assemblies.

2.2

Joint Industry Standards

J-STD-001

Requirements

for Soldered Electrical and Elec-

tronic Assemblies

2.3

Military

MIL-STD-2000 Rev. A

Standard

Requirements for Soldered

Electrical and Electronic Assemblies

2.4

Other Publications

IEC-TC-91

Proposed

International Standard (based on

J-STD-001) International Requirements for Soldered Electrical

and Electronic Assemblies using Surface Mount and Related

Assembly Technologies.

3.0

Test Specimens

The

components to be tested should

be the exact type and package style the tester intends to use

in production. A statistically valid number of each type and

package style of interest should be tested.

4.0

Apparatus

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.6.9.2

Subject

Test

to Determine Sensitivity of Electronic

Components to Ultrasonic Energy

Date

1/95

Revision

Originating Task Group

Ultrasonic Cleaning Task Group (5-31e)

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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4.1

Tank

Testing

shall be done in an ultrasonic tank, pref-

erably in the equipment to be used in production. Water is to

be used as the ultrasonic transmission testing fluid, regardless

of the cleaning agent to be used in the production process.

Water will degas, transmit ultrasonics, and cavitate more eas-

ily than most new cleaning agents and is, therefore, consid-

ered a ‘‘worst case’’ ultrasonic testing fluid. Care must be

taken to maintain water level during testing. Water tempera-

tures should be maintained at 60°C ±5°C (140°F ± 10°F).

It is recommended that testing equipment operate near 40Khz

or higher and have a power output in the range listed in the

chart below. Power is measured as the output from the gen-

erator to the transducers. Note in the chart that the amount of

power necessary is scaled for various tank sizes.

ank Size

liters (gallons)

Power Density

watts/liter (watts/gallon)

Magnetostrictive Piezoelectric

(5) 66-76 (250-290) 33-38 (125-145)

38 (10) 53-68 (200-220) 26.5-29 (100-110)

95 and greater

(25 and greater)

21-32 (80-120) 10.5-16 (40-60)

If frequencies other than 40 KHz range or power densities or fre-

quencies differing from the ranges listed above are to be used in

production, they should be used in testing as well, and noted on

the Ultrasonic Test Data Record.

4.2 Basket

Loose

components will be placed randomly in

a basket or in a beaker (pyrex or stainless steel) for testing. If

a basket is used, it should be made of stainless steel and

preferably have a solid bottom for optimal ultrasonic transmis-

sion. Tight mesh should always be avoided. If a beaker is

chosen, plastic is not acceptable as it will dampen ultrasonic

transmission.

5.1

Procedure

Note:

Standard ESD handling methods should be used in

handling and assembly so as not to have ESD damage misin-

terpreted as damage by ultrasonic exposure.

5.1.1

Perform

functional electrical tests on components to

be subjected to ultrasonic energy. All components should go

though standard prescreening tests to eliminate infant mortal-

ity. Note any anomalies and ignore any malfunctions in further

testing.

5.1.2 Fill

the test tank with de-ionized water. Turn on ultra-

sonics and allow a minimum of 15 minutes for the water to

degas. Evidence of cavitation should be obtained by placing a

piece of aluminum foil in the water for one minute and inspect-

ing for an erosion pattern (evidence of cavitational activity). If

the surface of the foil is not disrupted, continue to degas until

the foil confirms ultrasonic activity.

Test components in the equipment described above. Place

components randomly in basket or in a beaker. Baskets

should be suspended off the bottom of the tank or contain

stand off legs to keep it from setting directly on the bottom of

the tank. If a beaker is to be used, it should be filled with

deionized water and degassed as described in the above

paragraph. The beaker should be suspended in the water-

filled tank and not placed on the tank bottom.

Subject specimens to ultrasonics for a time period 10 times

longer than the expected exposure anticipated under normal

cleaning conditions or thirty minutes, whichever is longer.

5.1.3

(Optional)

Conduct

any environmental stressing

test(s) as specified by the reliability requirement of the product

line in concern.

5.2

Evaluation Method

5.2.1

Repeat

the functional electrical test in 5.1.1. Any fail-

ures should be analyzed for cause of failure. Any failure,

excluding those noted in 5.1.1 or attributable to a docu-

mented defect will also be considered caused by the ultrason-

ics.

5.2.2

Any

defect which is not assignable to a previously

documented defect will also be considered caused by ultra-

sonics.

5.2.3

Any

component exhibiting no failures or 100% reliabil-

ity after ultrasonic testing will be considered safely resistant to

ultrasonics under the conditions tested. Any component with

less than 100% reliability will be suspect unless subsequent

testing can demonstrate that it is 100% reliable. Unless clas-

sified or proprietary, please report test results to the Ultrasonic

Energy Task Group through the IPC for compilation in the

attached list.

It is important that the IPC receives as much data as

possible, whether it be to support previously submitted

data, add new data, or provide conﬂicting data for cer-

tain components. All information received will be

entered into a database for all IPC members to access.

The data will prove more useful as the volume of data

increases.

IPC-TM-650

Number

2.6.9.2

Subject

Test

to Determine Sensitivity of Electronic Components to

Ultrasonic Energy

Date

1/95

Revision

age2of4

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