1

HS Jang

Scanning Acoustic Microscope(SAM)Scanning Acoustic Microscope(SAM)

H.S. Jang

2

HS Jang

What is Ultrasonics ?What is Ultrasonics ?

• Sound waves which have

a frequency over 20kHz.

(Audible frequency: 16Hz - 20kHz)

• The sound waves which can not be heard by the human ear.

16Hz - 20,000Hz

3

HS Jang

Types of Ultrasonic WavesTypes of Ultrasonic Waves

1. Shear Wave1) The vibration direction and propagation direction are

perpendicular.

2) Transmission in liquid or air is impossible.

Vibration

Propagation

4

HS Jang

Types of Ultrasonic Waves Types of Ultrasonic Waves

2. Longitude Wave 1) The vibration direction and propagation direction are same.

2) Transmission in liquid is possible.

PropagationVibration

5

HS Jang

Characteristics of UltrasonicsCharacteristics of Ultrasonics

1. 100% reflection when it meets air(delamination)

2. Reflects at interfaces

3. Travels straight as light because of the very short wavelength.

AirDie

EMC

6

HS Jang

Advantages of UltrasonicsAdvantages of Ultrasonics

1. High resolution :Detectable minimum gap thickness of Sonix : 0.13 micro meter

2. High sensitivity : The measuring of size, location, shape of fine defects is possible.

3. Real time inspection is possible.

4. Safe : Harmless to human body.

7

HS Jang

Weak Points of UltrasonicsWeak Points of Ultrasonics

1. Difficult to inspect samples that have a rough surface or bubbles.

2. Liquid is required to transmit ultrasonic

3. Needs expertise(Solution:TAMI)

rough surface bubbles

8

HS Jang

Uses for UltrasonicsUses for Ultrasonics

1. Nondestructive test equipment.(S.A.M.)

2. Sonar to find submarine, fish-finder

3. Medical examination equipment

4. Cleaner(15~50KHz)

5. Humidifier

6. Welding(15~40KHz)

9

HS Jang

SONAR(Sound Navigation Ranging)SONAR(Sound Navigation Ranging)

10

HS Jang

SONAR(Sound Navigation Ranging)SONAR(Sound Navigation Ranging)

1000m

4 deg.C

11

HS Jang

Examination of Human BodyExamination of Human Body

Fetus Liver Pancreas

12

HS Jang

Reasons for Use of UltrasonicsReasons for Use of Ultrasonics

1. Evaluation of semiconductor reliabilityÅExisting the only estimation method of semiconductor reliability

2. Nondestructive inspection of internal defectsÅKeep fine defects which can be lost by destructive inspection

ÇReuse of good samples after inspection

13

HS Jang

Structure of QFPStructure of QFP

EMC

EpoxyCu Lead Frame

Cu L/FCu L/FSilicon Chip

Gold Wire

14

HS Jang

Detectable Defects Detectable Defects

1. Delamination2. Package Crack3. Die Crack4. Void5. Tilt6. Foreign Materials

DelaminationPKG CrackVoid

PKG Crack

Chip Crack

15

HS Jang

Structure of Flip ChipStructure of Flip Chip

UnderfillBump

Die

Substrate

16

HS Jang

Inspection using UltrasonicInspection using Ultrasonic

Signals in Digital Oscilloscope

PackageSurface

DieSurface

DieBottom

Inspect defects using reflected signalin each interface

Die Attach Adhesive

DieEMC Die Surface

Die Bottom

Package Surface

Ultrasonic

Transducer

GateGate

17

HS Jang

Inspection MethodsInspection Methods

1. Pulse Echo Methods1) A-scan : Inspection with waveform displayed on oscilloscope.

2) B-scan : Inspection with vertically x-sectioned 2-d image.

3) C-scan : Inspection with horizontally x-sectioned 2-d image..4) TAMI : C-Scan with multiple(2~999) gate

2. Thru-Transmission Method

1) T-scan : Inspection with transmitted signal.

18

HS Jang

Pulse Echo & Thru-TransmissionPulse Echo & Thru-Transmission

Pulse Echo Thru-Transmission

19

HS Jang

Structure of a Scanner Which uses both Pulse Echo and Thru-Transmission

Structure of a Scanner Which uses both Pulse Echo and Thru-Transmission

Water

Transducer for Pulse Generationand Receiver for Pulse Echo

Transducer for Thru-Transmission

20

HS Jang

A-ScanA-Scan

1. Inspect defects with the phase and the magnitude of reflected waves on oscilloscope.

2. Merit : The most accurate inspection method.

3. Weak Point : Only one point analysis is available not plane.

4. Used to confirm the inspection results.

PKG Surface Die Surface Die Bottom PKG Surface

Die Surface

Die Bottom

Ultrasonic

21

HS Jang

A-ScanA-Scan

Stethoscope

22

HS Jang

A-ScanA-Scan

PKG Surface Die Surface

23

HS Jang

A-ScanA-Scan

24

HS Jang

B-ScanB-Scan

1. Show the x-sectional image from each interface.

2. Detectable defects : Crack, Tilt and Void.

3. Merit : Analysis of the level of defects are possible.

25

HS Jang

B-ScanB-Scan

26

HS Jang

B-ScanB-Scan

27

HS Jang

B-ScanB-Scan

PKG Surface

PKG Crack

Die Surface

28

HS Jang

B-ScanB-Scan

29

HS Jang

EMC Void Insp.EMC Void Insp.

Void

Void

Void

No Void

Void

PKG Surface

Die Surface

30

HS Jang

Void Size MeasuringVoid Size Measuring

Void

Void

Void

No Void

Void

PKG Surface

Die Surface

VoidSize

31

HS Jang

Die Crack Direction InspDie Crack Direction Insp

PKG Surface

Die SurfaceDie Bottom

Die Surface

Die Bottom

Die Crack

Die Crack Direction

B-Scan Image

B-Scan

32

HS Jang

C-ScanC-Scan

1. Shows the horizontally x-sectioned images after focus at an interface.

2. Detectable defects : Delamination, Die crack.

3. Merit : The most precise inspection method.

4. Weak point : Needs expertise(Solution : TAMI).

33

HS Jang

C-ScanC-Scan

EMC

EMC

34

HS Jang

C-ScanC-Scan

Dimple Pad Bottom of TSOPDie Surface of QFP