Direct Wire Bonding to Substrate Vias via Deformed Bump
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Solution Overview
Problem
Conventional wire bonding techniques face challenges with direct connections to vias due to uneven surfaces, resulting in unstable and unreliable connections, and require traces from bond pads to vias, which can cause signal reflection noise and hinder compact substrate design.
Innovation Solution
The method involves deforming a ball over a via cap to form a bump, attaching a bond wire to the bump, and forming wedge or stitch bonds between the bond wire and the bump, eliminating the need for traces and ensuring stable connections by conforming to irregular via surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wire bonding techniques are used to connect to vias, then electrical connection is achieved, but the connection is unstable and unreliable due to uneven via surfaces
Solution Approach 1:
A ball is formed and deformed over the via cap before wire bonding to create a bump that pre-conforms to the uneven via surface. This preliminary action of forming the bump eliminates the need for the wire bond to directly contact the irregular via surface, thereby ensuring reliable connection despite surface non-uniformity
Solution Approach 2:
The bump acts as an intermediary element between the wire bond and the via cap. Instead of directly bonding the wire to the uneven via surface, the wire bonds to the bump which has already adapted to the via's irregularities, thus mediating the connection and ensuring stability
2Reliability
If traces are used to connect bond pads to vias, then electrical connection is achieved, but signal reflection noise increases and substrate design becomes less compact
Solution Approach 1:
The trace structure is extracted and eliminated from the design. Instead of using traces to connect bond pads to vias, the invention directly bonds wires to vias through bumps, removing the intermediate trace elements that cause signal reflection noise and occupy substrate space
Solution Approach 2:
The connection path is merged into a direct wire-to-via bond without intermediate traces. The bond pad connects directly to the via through the wire and bump structure, eliminating the separate trace layer and simplifying the overall substrate architecture
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 enables stable and reliable direct wire bonding to vias, reducing signal reflection noise and allowing for a more compact substrate design by eliminating the need for traces and improving electrical performance.
Implementation Method 1
deforming a ball over a via cap to form a bump
Implementation Method 2
forming a wedge bond or a stitch bond between the bond wire and the bump
Implementation Method 3
forming a wedge bond or a stitch bond between the bond wire and the bump
Data Source
AI summary
A method for electrically connecting an integrated circuit to a via in a substrate is disclosed. The method can include deforming a ball over the via to form a bump and attaching a bond wire to the bump. The method also can include attaching the bond wire to the integrated circuit, such as by forming an end of the bond wire into a second ball and deforming the second ball over the integrated circuit. Alternatively, the method can include forming an end of the bond wire into a ball and deforming the ball over the via. Embodiments of a disclosed integrated circuit and substrate assembly can include, for example, a bump aligned with at least a portion of a via in a substrate and a bond wire attached to the integrated circuit and the bump. Other embodiments can include a via with a top metal cap and an upper plating.