Failure analysis refers to technology that investigates defective products in detail to identify the failure mechanism and its root cause.

It has three purposes:

・Identifying the cause of defects

・Planning measures to prevent recurrence

・Improving design and processes

In other words, it is the last bastion of quality assurance.

The main triggers are:

・Electrical test failures

・Reliability test failures

・Field failures

・Frequent early failures

・Deteriorating yield

Field failures in particular are serious.

They lead directly to recalls and damage to the brand.

FA proceeds systematically.

① Symptom confirmation

Understanding electrical characteristics and failure modes

② Visual observation

Checking the exterior with a microscope or SEM

③ Non-destructive inspection

X-ray / SAT / CT

④ Fault localization

Narrowing down the failure location

⑤ Destructive analysis

Polishing and cross-section preparation

⑥ Material and structural analysis

Evaluating composition, crystals, and interfaces

⑦ Cause hypothesis → verification

(1) Optical Microscope (OM)

The first basic observation.

・Wire breaks

・Burn damage

・Cracks

・Contamination

(2) SEM (Scanning Electron Microscope)

High-magnification observation.

・Bump cracks

・Metal grain boundaries

・Electrochemical corrosion marks

・Fine fracture surfaces

(3) FIB (Focused Ion Beam)

Local cross-section preparation.

・The inside of TSVs

・RDL cross sections

・Fine interfaces

Structures can be checked at the nm level.

(4) EDX / Elemental Analysis

Identifies material composition.

・Foreign matter contamination

・Metal diffusion

・Oxidation state

(5) OBIRCH / TIVA

Detects failure points while powered.

・Locating leakage points

・Locating short circuits

Essential for leading-edge logic analysis.

In packages, many failures are structural in origin.

Typical examples:

・Solder cracks

・Disconnections caused by voids

・Delamination

・Wire lift-off

・Non-bonded bumps

Particularly in fan-out and HBM, defects related to RDL and TSVs are increasing.

FA is not easy.

Reasons:

・Defects do not reproduce

・Destruction erases evidence

・Multilayer structures make localization difficult

・There are often multiple combined factors

In other words, it is a technology that fuses “deduction” and “experimentation.”

In the era of AI and chiplets, FA is also evolving.

Examples:

・3D cross-sectional analysis

・Combined non-destructive + destructive analysis

・AI image analysis

・In-situ observation

Rather than simply identifying failures, it is beginning to function as a feedback mechanism for design improvement.

Failure analysis is directly linked to volume production.

Areas of impact:

・Yield improvement

・Process condition optimization

・Material change decisions

・Design rule updates

Companies with weak FA cannot raise their yields.

・Failure analysis is a technology for identifying the causes of defects

・It is the final line of defense for quality assurance

・It proceeds from non-destructive → destructive analysis

・Packages have many structural defects

・It is directly linked to volume-production yield

1.What is the ultimate purpose of failure analysis?

2.What is the difference between the roles of non-destructive inspection and destructive analysis?

3.What package-specific failure modes are there?

4.Why is FA directly linked to yield improvement?

 

Column Supervisor: Koji Kakumoto (President, OTIS Co., Ltd.)

After studying abroad and working in planning and development at a trading company, he joined OTIS Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as President, working to drive business growth and strengthen the organization.

 

This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.