IC Package Failure Analysis: Process and Methods

Failure analysis is a critical process in the manufacturing of IC (Integrated Circuit) packages. It involves investigating the conditions and failure modes of a chip after it malfunctions. This analysis is essential for ensuring the resilience, reliability, and security of chips. Discovery Engineering provides expert services in failure analysis and related electrical and electronic engineering areas.

What is Failure Analysis?

Failure analysis is the investigation of the conditions and failure mode of a chip after it fails. The primary goals are to verify the failure, understand the symptoms (failure mode), and determine the root cause. Identifying the root cause is crucial for guiding corrective actions and preventing future failures. Discovery Engineering’s Product Liability and Failure Analysis services play a vital role in this process.

Failure Analysis in the Design Process

The design process for IC packages is iterative, involving design, simulation, testing, and failure analysis. The process begins with design and simulation based on provided guidelines, leading to the creation of a prototype. In-process testing, such as wire pull tests and ball shear tests, assesses the physical resilience of the chip.

Electrical tests are also conducted to ensure all components function as intended. When failures occur, failure analysis is used to identify the cause. Accelerated cycling tests are performed to evaluate chip resilience under various working conditions. The investigation of failure modes and their root causes provides feedback for design, material, or layout modifications. This iterative cycle ensures continuous improvement of the chip.

Common IC Package Failure Modes

IC packages can fail in various ways. Common failure modes include:

• Die and substrate cracking due to stress or CTE (Coefficient of Thermal Expansion) mismatch.
• Wire and ribbon bond failures.
• Plating issues.
• Gold embrittlement of solder joints, known as purple plague.
• Loose conductive particles causing shorts or damage.
• Moisture-related failures like chemical corrosion, dendritic growth, and leakage.
• Electrical Overstress (EOS) or Electrostatic Discharge (ESD) failures.
• Plastic package failures due to stress.

Failure Analysis Testing Methods

Failure analysis employs both non-destructive and destructive testing methods. Non-destructive methods are used first to preserve the sample and determine its “as-is” condition.

Non-Destructive Methods

• Visual inspection: A basic examination of the package.
• Pin or particle impact noise detection test: Used to check for loose particles inside the package.
• Spectroscopy (X-rays, EDS): X-ray Energy Dispersive Spectroscopy (EDS) is a chemical analysis tool to determine the composition of the sample. X-rays can reveal voids, disconnected wires, and cracks.
• Microscopy (optical, scanning acoustic microscopy): Imaging methods to visualize the chip’s condition.

Destructive Methods

• Opening the encapsulant: Physically exposing the chip by breaking the package.
• Residual Gas Analysis (RGA): A chemical test to determine the gas composition inside the package.
• Wire pull test and ball shear test: Tests to measure the physical strength and resilience of wire bonds.
• Electron microscopy (SEM, TEM): Advanced microscopy techniques for detailed imaging.
• Focused Ion Beam (FIB): Another method for detailed analysis after opening the package.

Discovery Engineering’s expertise in electrical and electronic evidence is crucial in these testing stages.

Types of Test Results

Tests provide information about the physical and chemical properties of the IC package. Physical tests, such as microscopy, reveal cracks and other defects. Chemical tests, like EDS and X-ray analysis, determine the material composition.

Failure Analysis for Advanced Packages

Analyzing failures in advanced packages is more challenging due to their dense packing and 3D configurations. Exposing failure locations and preparing samples can be difficult, and image processing may have lower resolution. Techniques like simulations and electrical characterization, such as daisy chain resistance measurement, are used to aid in failure analysis. Emerging technologies like lock-in thermography (LIT) are being developed to image complex multi-layer components. Discovery Engineering’s Engineering capabilities are essential in addressing these complexities.

The Future of Failure Analysis

The field of failure analysis continues to evolve with the development of new technologies like lock-in thermography. Simulations and physical models are increasingly important for predicting failure scenarios. These advancements enhance the accuracy and effectiveness of failure analysis. Discovery Engineering’s Accident Reconstruction and Data Analysis expertise is valuable for these evolving methodologies.

IC Packaging Manufacturing Process

Failure analysis is a critical component of the IC packaging manufacturing process. It is an integral part of the iterative cycle of design, testing, and improvement. Testing methods, both destructive and non-destructive, are essential for identifying failure modes and root causes. Discovery Engineering’s expertise provides valuable insights into failure analysis for legal and technical contexts.

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