...using Acoustic Micro Imaging (AMI)...using Acoustic Micro Imaging (AMI)

Reveal hidden defectsReveal hidden defects……

What is Acoustic Micro Imaging?

Acoustic Micro Imaging (AMI) is a nondestructive

internal inspection technique that utilizes high frequency

ultrasound* in the range of 5 to 500 MHz.

*Ultrasound is defined as frequencies above 20 KHz

Why use Acoustic Micro Imaging?

1) determine interface bonding/adhesion

2) detect defects

3) characterize material properties

4) measure material properties

What materials are acoustically friendly?

• Polymers

• Metals

• Ceramics

• Composites

• Adhesives

• Solders

• Epoxies

• Paste

What key factors determine if an

application is acoustically friendly?

• Porosity

• Size and Shape

• Surface texture

C-Mode Scanning Acoustic Microscope

D9500 Series C-SAM

C-Mode Scanning Acoustic Microscope

C-Mode Scanning Acoustic Microscope

D24 Series C-SAM

Fast Automated C-Mode Tray Scanning System

FACTS2TM Series

Automated Bonded Wafer Inspection System

AW200 ™ Series C-SAM

Waterfall Transducer

Rotational Stage Fixture

Principles of Ultrasound

Within a given material ultrasound can be Reflected, Refracted, Transmitted, Scattered, Absorbed and/or

Blocked by changes relative to the surrounding material.

Porosity

& Voids

CrackAcoustic

Shadow

Delamination

Density

Variations

Transducer

Theory of Operation

Input Output (A-scan & Image)

XYZ Scan MotionWater

Tank/Bath

Note: 300 MHz = ~5 microns (u)

High FrequencyLow Frequency

Rule of thumb:

Ultra High Frequency (230+ MHz)

(ex. flip chip bump, bonded wafer, stacked die)

High Frequency (50-100 MHz)

(ex. uBGA, TSOP, flip chip under fill, capacitors)

Low Frequency (10-30 MHz)

(ex. BGA, PLCC, PQFP, capacitors)

1. Higher resolution

* shorter wavelength

* smaller spot size

2. Shorter focal length

3. Less penetration

1. Lower resolution

* longer wavelength

* larger spot size

2. Longer focal length

3. Greater penetration

Transducers

1

Si MetallizationSi MetallizationSi MetallizationSi Metallization

10 MHz10 MHz10 MHz10 MHz 100 MHz100 MHz100 MHz100 MHz 1 GHz1 GHz1 GHz1 GHz

Flip ChipsFlip ChipsFlip ChipsFlip Chips

Wafer BondingWafer BondingWafer BondingWafer Bonding

BGAsBGAsBGAsBGAs

Thick Film AdhesionThick Film AdhesionThick Film AdhesionThick Film Adhesion

Thin FilmsThin FilmsThin FilmsThin Films

Plastic ICsPlastic ICsPlastic ICsPlastic ICs

CSPCSPCSPCSP

Porosity & cracks in MetalsPorosity & cracks in MetalsPorosity & cracks in MetalsPorosity & cracks in Metals

CeramicsCeramicsCeramicsCeramics

Medical UltrasoundMedical UltrasoundMedical UltrasoundMedical Ultrasound

Hermetic Seal IntegrityHermetic Seal IntegrityHermetic Seal IntegrityHermetic Seal Integrity

Frequency vs. Applications

•The A-scan displays the mechanical signature (waveform) that corresponds to the position of the transducer over the sample.

•The A-scan is based on the acoustic impedance, thickness and velocity of the respective material(s).

•The A-scan includes time, amplitude and polarity (phase) information

A-scan Waveform Display

•Acoustic Impedance (Z) - is the product of a materials density times its ultrasonic velocity

Z = r V

•In practical terms - Acoustic Impedance is a materials characteristic property that

determines the amount of reflected and transmitted energy that occurs when an

ultrasonic wave encounters a boundary or interface between two materials.

Acoustic Impedance

Determines Echo

Polarity & Amplitude

R / I = (Z2 - Z1) / (Z2 + Z1)

Incident (I) Reflected (R)

Z1

Z2

CASE 1 Z2 > Z1

CASE 2 Z2 < Z1

CASE 3 Z2 = Z1

A-scan Waveform Display

Transducer T

R

21 3

21 3

TimeFIE

A-scan Amplitude, Polarity & Color Maps

Large Positive

Positive

No Signal

Negative

Large Negative

SymmetricAsymmetric

A-SCAN SURFACE SCAN C-SCAN

MULTI-SCAN

Q-BAM™ ZIP-SLICE & 3V™

BULK-SCAN THRU-SCAN

VRM ™ (Virtual Rescan Mode) with FDI & ASF

Modules

Imaging Modes

1 - Die Surface/Mold Compound (Interface Scan)

2 - Die Attach (Interface Scan)

3 & 7 - Lead Frame/Mold Compound (Interface Scan)

4 - Plastic Encapsulate

Void & Filler Distribution (Bulk Scan)

Material Characterization (Interface Scan)

5 -Die Pad/Molding Compound (Interface Scan)

6 - Surface Image (Surface Scan)

Plastic

Integrated

Circuit (PIC)

C-scan Interface Scan Technique

C-scan Interface Scan Technique

C-scan Bulk Scan Technique

Plastic Integrated Circuit (PIC) “Popcorn Crack”

ZIP-SLICE

Plastic Integrated Circuit (PIC)Virtual Volumetric View (3V Profile) “Popcorn Crack”

1 - Surface Image (Surface Scan)

2 - Die Crack (Bulk Scan)

3 - Solder Bridging (Interface Scan)

4 - Chip to Underfill (Interface Scan)

5 - Underfill Voids (Interface Scan, Bulk Scan)

6 - Bump to Substrate (Interface Scan)

7 - Bump Integrity (Interface Scan, Bulk Scan)

Flip Chip/C4(Controlled Collapsed

Chip Connection)

CC--Scan of Chip/Underfill and Bump Level Showing Filler Scan of Chip/Underfill and Bump Level Showing Filler

Particle Density Variation and Voids in the UnderfillParticle Density Variation and Voids in the Underfill

C-SCAN

CSP Flip Chip - Underfill

CC--scan Imagescan Image

Void/disbond Void/disbond ––

focused and gated at focused and gated at

the chip to underfill the chip to underfill

(upper) level (upper) level

CC--scan Imagescan Image

Void/disbond Void/disbond –– focused focused

and gated at the and gated at the

underfill to substrate underfill to substrate

(lower) level (lower) level

MULTI-SCAN

C4 Flip-chip Solder Bump Inspection

230 MHz C230 MHz C--scan Image scan Image

Voids/disbonds Voids/disbonds –– focused focused

and gated within the and gated within the

solder ballssolder balls

180 MHz C180 MHz C--scan Imagescan Image

Voids/disbonds Voids/disbonds –– focused focused

and gated within the and gated within the

solder ballssolder balls

C-SCAN

1 - Lid Seal (Interface Scan)

2 - Substrate Attach (Interface Scan)

3 - Die Attach (Interface Scan)

4 - Lead Attachment (Interface Scan)

5 - Multi-Layered Package (Interface Scan, Bulk Scan,

SLAM, TOF, Loss of Back Echo)

HybridsHybrids

Hybrids - GaAs Die Attach Inspection

SURFACE SCAN C-SCAN

Surface

(C-scan)

Focused Focused

and gated and gated

at the at the

surfacesurface

Subsurface

(C-scan)

Disbond Disbond --

focused and focused and

gated at the gated at the

die attach leveldie attach level

1 - Cracks (SLAM, Loss of echo, bulk scan, Q-BAM, TOF)

2 - Voids (SLAM, Loss of echo, bulk scan, Q-BAM, TOF)

3 - Delamination (SLAM, Loss of echo, bulk scan, Q-BAM, TOF)

4 - Porosity (SLAM, Loss of echo, bulk scan, Q-BAM, TOF)

5 - Surface Imperfections (Surface Scan/SLAM)

6 - Shifted Electrodes (SLAM)

MultiMulti--layered layered

Ceramic Chip Ceramic Chip

Capacitor Capacitor

(MLCC)(MLCC)

MultiMulti--layered Ceramic Chip Capacitor (MLCCC)layered Ceramic Chip Capacitor (MLCCC)

Q-BAM

Q-BAM (focused

B-scan image)

Disbond (left sample) Disbond (left sample)

-- focusedfocused and gated and gated

within the bulk ceramicwithin the bulk ceramicC-SCAN

C-scan image

Disbond (left sample) Disbond (left sample)

-- focused and gated focused and gated

within the bulk within the bulk

ceramicceramic

Image Analysis % Area

Image Analysis - Measure Distance

Virtual Rescanning Module (VRMTM)

VRMTM – Frequency Domain Imaging (FDI)

141 MHz

175 MHz

167 MHz

195 MHz 226 MHz

Original Reconstruction

VRMTM – Frequency Domain Imaging (FDI)

VRMTM Acoustic Surface FlatnessASF Module

• A major new “tool” for Failure Analysis Labs• For a modest additional cost and training, and no

additional floor space, the customer gets the benefits and capability of an additional new “tool”.

• Compliments current capability by providing the analyst a new means to determine what is wrong with a part.

Die and Substrate Warpage: Bow

The center of the Die and Substrate is higher than the corners.

Die only:

Acoustic Reflection

Die only:

Acoustic Flatness

Die

Substrate

Substrate:

At least 80 µm of bow

Acoustic Flatness

PC Board: Warpage

If the PC Board isn’t a flat plane, then there can be solder problems.

Acoustic Reflection

PC Board Warpage: Acoustic DataThe acoustic data shows that there is about a 400 µm difference from the highest to the lowest point on the PC board.

Acoustic Reflection

Acoustic Flatness Image

PC Board Warpage: Acoustic Data

mm

mm

The acoustic data shows that there is about a 400 µm difference from the highest to the lowest point on the PC board.

BGA Warpage on PC Board

Warpage (ccc) measured at ~35 µm.

Acoustic Reflection

Surface Internal Substrate

Acoustic FlatnessAcoustic Flatness

Projected Image

Substrate WarpageSubstrates

warpage can be either bow or warp.

Bow is shown here. The dark corners indicate that the center is bowed out.

Warp is like a potato chip shape (bent in two directions at the same time).

Thickness of the films on the substrate can also be measured. Acoustic Flatness

Analysis ToolAnalysis ToolAnalysis ToolAnalysis ToolAccurately look at horizontal and vertical linescans.

Modification of B-Scan imaging in VRM.

The shift in the line scan allows measurement of the layers on the substrate.

Simulated