Copper Thermal Bonding Sheet for Precise Power Semiconductor Joining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sintered metal particle-containing pastes, mainly using silver, are expensive and result in variations during application, leading to a lower yield ratio of bonded bodies in power semiconductor devices, which require high heat dissipation and reliability.
Innovation Solution
A thermal bonding sheet comprising a pre-sintering layer with copper particles and polycarbonate as a binder, where the polycarbonate decomposes at a lower temperature than the copper particles, allowing for suitable sintering and improved bonding without the use of expensive noble metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a resin sheet is used as a bonding sheet for bonding power semiconductor elements, then bonding strength is improved, but outgassing occurs during bonding that contaminates the vacuum environment and reduces manufacturing precision
Solution Approach 1:
A release sheet is introduced as an intermediary layer between the resin sheet and the power semiconductor elements. This release sheet prevents resin from adhering to the elements during bonding while allowing precise positioning. The release sheet with its specific surface properties enables the resin to bond to the elements without direct contact, thus preventing contamination and maintaining manufacturing precision.
Solution Approach 2:
The bonding system is segmented into multiple functional layers: a resin sheet for bonding, a release sheet for preventing adhesion, and a dicing tape for positioning. This segmentation allows each component to perform its specific function independently, with the release sheet and dicing tape working together to maintain precision while the resin sheet provides bonding strength.
2Strength
If a resin sheet is heated for bonding, then bonding strength is improved, but resin outgassing contaminates the vacuum environment
Solution Approach 1:
The release sheet acts as a mediator that allows thermal energy to be transferred for bonding while preventing resin outgassing from directly contaminating the vacuum environment. The release sheet's structure enables controlled outgassing away from the semiconductor elements while maintaining the vacuum integrity.
Solution Approach 2:
The resin outgassing, which would normally be harmful contamination, is converted into a beneficial effect by the release sheet that directs the outgassing away from the semiconductor elements. The harmful outgassing is thus transformed into a process that does not compromise the vacuum environment or product quality.
3Strength
If power semiconductor elements are bonded directly with resin, then bonding strength is improved, but resin adhesion to elements causes positioning errors
Solution Approach 1:
The release sheet serves as an intermediary that prevents resin adhesion to the power semiconductor elements while allowing the elements to be precisely positioned. The dicing tape with positioning marks works in conjunction with the release sheet to ensure accurate element placement without resin interference.
Solution Approach 2:
The bonding system is divided into separate functional components: the resin sheet for bonding, the release sheet for adhesion control, and the dicing tape for positioning. This segmentation allows each component to optimize its function without interfering with others, ensuring both bonding strength and positioning accuracy.
4Productivity
If multiple bonding sheets are stacked for processing, then productivity is improved, but alignment between sheets becomes difficult reducing manufacturing precision
Solution Approach 1:
Multiple functional features are merged into a single dicing tape structure that provides both positioning marks for alignment and support for stacking multiple bonding sheets. The dicing tape integrates alignment guidance, sheet support, and processing guidance functions, enabling precise alignment while maintaining productivity through efficient multi-sheet processing.
Solution Approach 2:
The dicing tape acts as an intermediary structure that facilitates precise alignment between multiple stacked bonding sheets. The positioning marks on the dicing tape provide reference features that enable accurate alignment, while the tape itself serves as a common support base for multiple sheets during processing.
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
The solution provides a cost-effective thermal bonding sheet that enhances the yield ratio of bonded bodies and maintains high thermal characteristics and reliability for power semiconductor devices operating in severe heat environments.
Implementation Method 1
a resin sheet or a film having a bonding sheet structure... to bond power semiconductor elements mounted on upper and lower substrates to each other
Data Source
Figure 1~3
Figure 4
AI summary
A thermal bonding sheet includes a pre-sintering layer containing copper particles and polycarbonate.