Optical Leak Testing Technology October 9th, 2014 Hermetic Leak - - PowerPoint PPT Presentation

Optical Leak Testing Technology

October 9th, 2014

Hermetic Leak Test Methods

Helium Mass Spectrometry (Fine) Bubble Leak testing (Gross) Dye Penetrant (Gross) (Destructive) Residual Gas Analysis (Destructive) Cumulative Helium Leak Detection ( Fine and Non-Batch Gross) Optical Leak Testing ( Fine and Gross Batch Testing)

Historic Limitations and Technical Issues

Conventional HMS, and Bubble Leak Testing

Helium absorption on the package body High bomb pressures and long cycle times One way leakers “Virtual leakers” Inability to test at the board level Repeatable leak rate test coverage in the 10-05 cc- atm/sec range Problems with helium backfills Product contamination and masking of fine leaks during bubble testing Costs of flourinert , and environmental concerns using perfluorocarbon with bubble leak testing

Range of Leak Sensitivity (Component Level)

Bubble Helium Optical Leak Test True Leak Rate (deceasing )

Gross Leak -6 Fine Leak

Only Optical Leak Testing covers the full required test range in one method.

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Optical Leak Testing

Features

Simultaneous gross and fine leak inspection on up to 200 devices in a single test Shortened test cycles (eliminates He bombing) Quantitative results in cc-atm/second, He Can test PC board mounted devices One-step calibration and setup High volume production testing Results can be networked for SPC or to a pick and place machine to remove rejected devices.

Component Testing

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Sources of Leaks in Packages

Along the weld At the glass to metal feedthrough Or through a defect in the package itself

Optical Leak Testing

Test Procedure

Optical Leak Testing

Test Procedure

Start Test Package Lid is Flat End Test Gross

• r Open

Fine Leaker Hermetic Sealed No Change Lid Moves Up Chamber Pressure Deforms Lid

Optical Leak Testing Schematic Diagram

OPTICAL LEAK TEST SYSTEM SCHEMATIC DIAGRAM

LASER DIGITAL CCD CAMERA 1-200 HERMETIC WINDOW SYSTEM COMPUTER IMAGE PROCESSOR PACKAGES

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TEST CELL 1-5 BAR HELIUM

Laser Interferometer Phase Maps

Hermetic:

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fringe Gross: no fringes. No lid movement. Fail: Many fringes indicate lid moving up. 1 fringe = 0.26 um = ½ wavelength of light

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Example of Leaking Device

and Relative Lid Deflection

Optical Leak Testing

Fine Leak Testing

Optical Leak Testing

Fine Leak Testing

True Leak Rate Measurement Achieved by:

• Determining lid deflection (um) due leak in

the package.

• Modulating the chamber pressure

sinusoidally to determine lid stiffness (um/psi).

• Lid Stiffness: um/psi
• Modulate the chamber pressure

sinusoidally to determine lid stiffness.

60.1 psig 60.0 psig 59.9 psig

Test Pressure Start End of test

• Leakage is change in package pressure.
• Leakage= Lid movement (um)

Lid stiffness (um/psi)

• Leak Rate = - Ln Delta P final V

Delta P initial t

• Volume (cc) is free air volume.
• t (sec) test time in seconds.
• Delta P initial = test pressure.
• Delta P final = test pressure – leakage.

• The measured leak rate is converted to a

standard leak rate by dividing by the chamber pressure.

• Leak Rate (standard) = Leak Rate (measured)

Test Pressure (atm)

• The output from the Optical Leak Tester

is a true leak rate (cc-atm / sec) which is called “L” in MIL-STD-883.

• OLT can test to the ‘11’s Lair or ‘14’s R1
• Recent test on wafer level device.
• 24 hours, 64 psig, 0.01 cc,
• stiffness -0.05 um/psi.
• Lhe = 1.04 x 10-10 cc-atm/sec (actual)
• Lair = 3.87 x 10-11 cc-atm/sec (calculated)
• R1 = 3.93 x 10-14 cc-atm/sec (calculated)
• OLT can match the test sensitivity or any leak

test method available including Krypton 85.

System Operation

System Operation

Testing a full matrix of pig tailed butterfly packages.

Butterfly devices in process tray Operator places tray into system

Operator Chooses the Appropriate Part number The operator then presses Start

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Automatic Test Analysis with a set Accept/Reject threshold shows 6 leaking and 4 hermetic packages.

Test Results

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Test In Progress

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Optical Leak Test Systems

• Collected on production parts from

Vectron International, Hudson NH beginning in Jan 2003

• Three different package volumes/styles

and four different machines

• Over 110,000 parts tested, only a very

small percentage of parts failed and were confirmed by conventional HMS and bubble test per TM 1014

• During Beta site testing the parts were

tested to equivalent air leak rate below 1EE-08 cc/sec air.

Beta Site Production Test Data

• Collected on production parts from

Vectron International, Hudson NH beginning in Jan 2003

• Three different package volumes/styles

and four different machines

• Over 110,000 parts tested, only a very

small percentage of parts failed and were confirmed by conventional HMS and bubble test per TM 1014

• During Beta site testing the parts were

tested to equivalent air leak rate below 1 EE-08 cc/sec air.

Volume .03cc 5 mil thick kovar lid (7.5 X 7.5 mm) 50 psi chamber pressure, 4 minute test Test Sensitivity level set at 7.4 X10-09 cc/sec LHe Equivalent to 2.7X10-09 cc/sec AIR

Package Details (XTAL Oscillators)

Volume .1cc 5 mil thick kovar lid (7X14mm) lid stiffness 1 μm/psi 25 PSI chamber pressure, 4 minute test Test Sensitivity level set at 9.8 X10-08 cc/sec LHe Equivalent to 3.7X10-08 cc/sec AIR

Package Details (XTAL Oscillators)

Source: Vectron Qual Data

X-Tal PKG A: # Tested TM 1014 Rejects OLT Rejects (gross/fine) Machine #1 3106 12 12 Machine #3 2582 20 19 X-Tal PKG B: Machine #1 892 Machine #3 892 Totals 7742 32 31 Bottom Line:

.01% of total parts tested (only one in 7742) passed using OLT but failed TM 1014

Machine Qualification Test Data

Testing Board Mounted Devices

Discrete hermetic devices that pass MIL STD 883 helium testing may fail during or after board assembly due to helium absorption. Because Optical Leak Testing is not subject to gas absorption issues, devices on assembled circuit cards can be leak tested with OLT.

Optical Leak Testing History

MIL-STD-883

• Included into MIL-Std-883 Method 1014 in 1995.
• Updated in 2004 for Gross and Fine leak testing on

both individual, components and board level testing.

• The system outputs true leak rate instead of lid

deflection.

• Leaking devices samples are no longer needed for

calibration.

• Revision J draft has been submitted to DSCC (DLA)

in May of 2012.

• Failure criteria and test methodology is better defined.

Optical Leak Testing History

MIL-STD-883

• Included into MIL-Std-883 Method 1014 in 1995.
• Updated in 2004 for Gross and Fine leak testing on

both individual, components and board level testing.

• The system outputs true leak rate instead of lid

deflection.

• Leaking devices samples are no longer needed for

calibration.

• Revision J draft has been submitted to DSCC (DLA)

in May of 2012.

• Failure criteria and test methodology is better defined.

Optical leak testing using advanced laser interferometry technology

• Tests for Gross and Fine leaks in one test
• No Helium bombing required
• No Helium absorption problems
• Eliminates bubble leak testing for gross leaks
• Used in production in the following industries:

MEMS, communications, micro-electronics, automotive and aerospace devices and sensors, implantable medical electronics.

• Mature technology with a proven track record.

(Over 100 systems installed worldwide)

Presentation Contact

Chris Aubertin

• Tel. 610-592-0167

ttrafford@NorComSystemsInc.com