Case Study
Resolving Die Peel Issues in an Automotive & Aerospace Electronics
Background
A global electronics manufacturer supplying critical components to the automotive and aerospace industries received multiple customer complaints regarding the premature failure of transistor-based power modules. Field analysis revealed that the root cause was die peel – a separation between the semiconductor die and its substrate, leading to thermal instability, electrical failure, and ultimately, component malfunction.
These failures risked ECU (Electronic Control Unit) shutdown in vehicles and avionics communication errors, making this a safety-critical issue.
Problem Statement
- =Customer Complaints: Intermittent or total failure of power modules in ECU and control systems.
- = Technical Failure Mode: Die peel (delamination between the die and substrate) in transistor packages.
- =Impact:
- KIncreased field failures and warranty claims.
- K Line stoppages at customer assembly plants.
- KEscalated audits and threat of delisting from approved supplier lists.
- =Estimated Cost Impact: £1.1 million (field returns, rework, replacement shipments, and lost production time).
Root Cause Analysis
A cross-functional investigation team used 8D and microsection analysis, uncovering the following contributing factors:
1. Material Issues:
- Inconsistent die attach adhesive application and curing parameters.
- Use of a die attach material with poor thermal expansion compatibility.
2. Process Variation:
- No real-time monitoring of die attach pressure or temperature during bonding.
- Variations in plasma cleaning process led to residual contamination before die placement.
3. Design and Packaging Influence:
Package design lacked mechanical features to prevent delamination under cyclic thermal stress (especially critical in aerospace environments).
4. Lack of Process Control:
No Statistical Process Control (SPC) on die attach thickness or bondline integrity.
Case Study Highlights
Corrective Actions & Solution Implementation
Material and Process Controls
Switched to a high-reliability die attach epoxy with proven aerospace qualification and matched CTE (coefficient of thermal expansion).
Standardized and optimized plasma cleaning parameters with real-time process verification.
Introduced automated dispensing and curing systems with closed-loop control for adhesive quantity and bondline thickness.
Design Improvements
Reworked power module design to include mechanical stress relief structures (die support structures and corner radius modifications).
Conducted Finite Element Analysis (FEA) to validate design under thermal cycling loads typical in engine bay and avionics environments.
Advanced Process Monitoring
Implemented in-line AOI (Automated Optical Inspection) and bondline X-ray inspection post-die attach.
Introduced SPC for die placement force, temperature, and adhesive volume, ensuring Cp/Cpk > 1.33 for key parameters.
Testing & Qualification Enhancements
Expanded HALT/HASS testing protocols to simulate 1000+ thermal cycles.
Added shear testing and bondline integrity checks to every batch before shipment.
Customer & Quality System Engagement
Held technical review sessions with key customers to share root cause and solution roadmap.
Updated PFMEA and Control Plans; added layered audits for high-risk steps.
Launched a containment program to inspect and requalify all in-process and shipped inventory.
Results & Impact
This case demonstrates how complex failure modes like die peel in high-reliability electronics can be resolved through a combination of material science, design optimization, and process control. By addressing both technical and systemic gaps, the company not only eliminated field failures but restored customer trust and audit readiness, positioning itself as a robust supplier for mission-critical automotive and aerospace electronics.
%