Flip-Chip Support Structure to Prevent Lead Edge Shorting
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Solution Overview
Problem
During the dicing process of wafers, metal burrs and cut surfaces on chip edges can lead to short circuits or electrical abnormalities when leads on circuit boards contact these metal residues during bonding.
Innovation Solution
The chip design includes a supportive element protruding from its active surface, positioned between the bump for lead bonding and the chip's edge, which supports the lead, preventing it from contacting metal cut surfaces or burrs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead is bonded directly to the bump without additional support structures, then the bonding process is simpler, but the lead contacts metal cut surfaces or metal burrs causing short circuits or electrical abnormalities
Solution Approach 1:
The supportive element acts as an intermediary between the lead and the chip edge. It provides a non-conductive support structure that holds the lead in a suspended position, preventing contact with metal burrs or cut surfaces while maintaining the electrical connection through the bump. This mediator approach resolves the contradiction by adding a simple supportive structure rather than fundamentally changing the bonding process.
Solution Approach 2:
The chip structure is segmented into functional zones: the bump area for electrical bonding, the supportive element area for mechanical support, and the suspended lead area for electrical connection. This segmentation allows each component to perform its specific function without interfering with others, improving reliability while keeping the overall structure manageable.
2Object-affected harmful factors
If the lead is suspended over the chip edge using a supportive element, then contact with metal burrs is prevented, but the chip structure becomes more complex
Solution Approach 1:
The supportive element provides beforehand cushioning by creating a protective barrier between the lead and potential harmful contacts with metal burrs or cut surfaces. This preventive structure is built into the chip design before bonding, ensuring that even if metal burrs are present, they cannot cause short circuits. The cushioning approach addresses the harmful factor directly while maintaining structural simplicity.
3Reliability
If the bump height is increased to improve bonding, then bonding reliability improves, but the lead may contact metal cut surfaces more easily
Solution Approach 1:
The solution moves from a one-dimensional vertical height adjustment to a two-dimensional spatial arrangement. Instead of only increasing bump height, the lead is positioned in a suspended state above the chip edge using the supportive element. This dimensional change allows the lead to be elevated away from metal cut surfaces while maintaining optimal bonding height, resolving the contradiction between bonding reliability and harmful factor prevention.
Data Source
AI summary
A chip provided to be flip bonded to a circuit board includes at least one bump and at least one supportive element which protrudes from an active surface of the chip and is located between the bump and a first side of the active surface. The supportive element is provided to support a lead on the circuit board to prevent the lead from contacting a metal burr protruding from the active surface or a metal cut surface exposed on a side wall of the chip. The supportive element can protect the chip and the lead from short circuit or electrical abnormality.