Die-Substrate Locking Features for Shock-Resistant Die Attach
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Solution Overview
Problem
The existing methods for attaching a die to a substrate in power electronics are prone to misalignment and dislodgment during transportation due to shock and vibration, leading to failures in high-cost electronic parts like power modules.
Innovation Solution
A method involving the formation of locking features in the substrate's metal layer and the use of a die-transfer film to create a tacked-stack-up, which is then subjected to heat and pressure during a hot-tack process to strengthen the bond, allowing the stack-up to withstand transportation without dislodgment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a die is temporarily attached (tacked) to a substrate using conventional methods, then the die can be positioned for subsequent soldering, but the bond strength is insufficient to withstand shock and vibration during transportation
Solution Approach 1:
The locking features are formed in the substrate's metal layer before the die attachment process. These pre-formed features (such as recesses, protrusions, or patterned structures) are designed to mechanically interlock with corresponding features on the die or die carrier, providing enhanced bond strength from the outset and preventing dislodgment during transportation.
Solution Approach 2:
The locking features are strategically positioned at specific locations on the substrate's metal layer where mechanical interlocking is most needed. This localized approach enhances bond strength at critical attachment points without requiring complex modifications across the entire substrate surface, thus improving reliability while maintaining reasonable structural simplicity.
2Reliability
If the die is firmly bonded to the substrate, then transportation shock and vibration can be withstood, but alignment precision during the attachment process becomes more difficult to achieve
Solution Approach 1:
The locking features are designed as discrete, segmented elements distributed across the substrate surface rather than a continuous complex structure. This segmentation allows the die to be aligned with individual features independently, making the alignment process more manageable while the collective action of multiple locking features provides robust resistance to shock and vibration during transportation.
3Ease of manufacture
If conventional tacking methods are used, then the attachment process is simple, but the bond strength is insufficient and leads to failures in high-cost electronic parts
Solution Approach 1:
The locking features are designed to automatically engage and provide mechanical interlocking during the die attachment process without requiring additional complex steps or specialized equipment. The substrate's metal layer structure itself provides the locking mechanism, making the process self-sufficient and maintaining simplicity while dramatically improving bond strength and preventing failures in high-cost electronic parts.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the bond strength of the die to the substrate, reducing failures and improving production yield by ensuring proper alignment and attachment during subsequent soldering processes.
Implementation Method 1
heating the substrate so that a temperature of the stack-up is raised during the hot-tack period
Implementation Method 2
sintering the tacked-stack-up so that the die is bonded to the substrate
Data Source
AI summary
A die-attach process that creates a bond strength sufficient to hold a die to a substrate while it is handled before being permanently attached is disclosed. The die-attach process includes forming locking features in a metal layer of a substrate so a bond at the die-substrate interface is strengthened. The locking features may include a plurality of cavities or slots formed in a metal layer of the substrate. The cavities and slots can increase a surface area and provide anchor points for a die-attach film placed between the die and the substrate.