1 Acoustic Microscopy of High-Reliability Electronic Components Jo Wilson / Bob Hussey - RJ Technical Consultants John Jones - ALTER Technology Group (UK.

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Acoustic Microscopy of High-Reliability

Electronic ComponentsJo Wilson / Bob Hussey - RJ Technical Consultants

John Jones - ALTER Technology Group (UK Office)

Chris Gartside - USL Ultrasonic Sciences Ltd (UK)

USL Ultrasonic Sciences Ltd

Bois MoreauBois MoreauF-17770 JuicqF-17770 Juicq

Charente MaritimeCharente MaritimeFranceFrance

Tel : +33 5 46 95 35 10Tel : +33 5 46 95 35 10

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Immersion systems Squirter systems

• Systems for inspection aero composite structures• Systems for inspection of tube and bar• Systems for use in the railway and automotive

industries• Inspection of hollow railway axles• Acoustic microscopes• USL Expansion boards• PM30 Pulser Receiver (with linear & log amplifiers) • PHASYS phased array system • Multiplexers

USL Ultrasonic Sciences Ltd

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ACOUSTIC MICROSCOPE APPLICATIONS TO MICROELECTRONICS

John Jones, ALTER Technology Group, UK Office

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A typical failure analysis sequence – electrical measurement has identified open circuits – radiographic inspection had found no defects – CSAM identified delamination of the die surface (pop-corning) – de-encapsulation and SEM confirmed that ball bonds had been torn from the die surface.

CSAM and FAILURE ANALYSIS

Optical Image X-Ray Image CSAM Image

SEM Image

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CSAM and COMPONENT EVALUATION

Radiographic ImageThe image shows the die, die attach, lead frame and the bond wires

CSAM ImageThe image also shows the plastic tie bar used to support the lead frame and a heat spreader below the die

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CSAM and COMPONENT SCREENING

Water is the transmission medium used in acoustic microscopy.

Water ingression may occur during scanning and it is essential that the microscope user under stands the processes involved.

It is also essential that the components are protected after screening. ATG recommend an 85C bake for 48 hours with the screened components vacuum packed with a moisture indicator and a desiccant in an impervious A/S bag.

In 2007 and 2008 ATG processed 135 lots for a space customers no field failures were reported

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CSAM and COUNTERFEIT COMPONENTS

The CSAM image shows six PEMS taken at random from six tape and reels found to contain counterfeit parts.

One date code was found to have a totally different acoustic response.

Micro-sectional analysis found a different filler in the encapsulant and no fire retardant!

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• A surface mounting RF isolator using a metallised ferrite.

• The ferrites used are very brittle and prone to cracking.

• Cracks can be detected optically but it is time consuming.

• CSAM can detect cracks in seconds.

OTHER SCANNING ACOUSTIC MICROSCOPY APPLICATIONS

FERRITES

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• Multi layer ceramic capacitors are used in filter connectors where short circuit failures due to cracks and delaminations can have serious effects on system reliability.

• Cracks and delaminations can be readily detected on the ceramic piece parts before the connector is assembled.

OTHER SCANNING ACOUSTIC MICROSCOPY APPLICATIONS

CERAMIC CAPACITORS & FILTERS

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OTHER SCANNING ACOUSTIC MICROSCOPY APPLICATIONS

CIRCUIT BOARDS

The CSAM image shows two RF circuit boards approximately 200mm by 100mm.

The boards were imaged to assess, non-destructively, the adhesion of the tracks, green line in these images.

The boards were also assessed for the quality of the boards, absense of voids etc.

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• Copper tungsten alloy (CuW) is impervious to normal x-rays.

• A detector is soldered onto a copper tungsten alloy heatsink.

• Copper tungsten is not impervious to ultrasound

• Voids in the solder used to mount the detector are easily observed.

OTHER SCANNING ACOUSTIC MICROSCOPY APPLICATIONS

SOLDER DIE ATTACH

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Publications and Contacts

• COTS Reliability Assessment, CMSE Europe, 2010 – Ron Fidler and John Jones.

• Counterfeit Components, Encapsulation Considerations, UK COG Conference 2007 – John Jones

• Contacts• COTS Reliability – [email protected]• COTS Reliability – [email protected]• CSAM Services – [email protected]• COTS Services – [email protected] (David Numez)

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USL Ultrasonic Sciences Ltd

Typical USL acoustic microscope(200MHz version)

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USL Ultrasonic Sciences LtdImmersion tank with tray of plastic IC packages

Through transmission adaptor, useful for rapid screening of parts for delamination or popcorn-type defects that may occur in different levels in the part

BGA (ball grid array)

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USL Ultrasonic Sciences LtdUSL acoustic microscope system adapted for inspection of PCB assemblies on a conveyor belt system.

Irrigated transducer- programmed to scan target areas.

Fast scan time (few seconds per component depending on resolution).

Popcorn-type defects, a low resolution scan easily reveal defects in a scan of 3 seconds.

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USL Ultrasonic Sciences LtdMuch higher resolution scans are needed however to detect other defects, e.g. •disbond limited to areas at the corners of the die (left image) •small disbond areas at the leadframe (right image).

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USL Ultrasonic Sciences Ltd

Unit 4 Springlakes Industrial Estate, Deadbrook Lane, Aldershot, Hampshire, GU12 4UH, EnglandTel: + 44 (0)1252 350550 Fax: + 44 (0)1252 350445E mail: [email protected] Internet: http://www.ultrasonic-sciences.co.uk