Die Pad Concave Structure for Metal Paste Containment
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Solution Overview
Problem
The existing methods for bonding semiconductor chips to die pads using solder or metal pastes face issues such as excessive spreading, overflow, and partial defects, which affect the reliability and yield of semiconductor devices.
Innovation Solution
A die pad with a concave structure is used, where the concave structure is positioned directly under the sides of the semiconductor chip, with varying recess dimensions and corner portions to guide the metal paste and prevent it from flowing onto the upper surface, ensuring proper bonding and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal paste is used for bonding semiconductor chip to die pad, then bonding is achieved, but paste spreading and overflow occur causing bonding defects
Solution Approach 1:
The die pad surface is segmented into a bonding region and a non-bonding region by introducing a concave structure. This segmentation confines the metal paste to the bonding region during the bonding process, preventing paste spreading and overflow onto the non-bonding region, thereby improving paste placement control while maintaining bonding quality
Solution Approach 2:
The die pad surface is given different local qualities through the concave structure: the bonding region has a lower surface level (concave) to accept and contain the metal paste, while the non-bonding region remains at the original surface level. This local differentiation ensures paste confinement to the appropriate area, preventing defects without affecting overall bonding performance
2Reliability
If conventional flat die pad surface is used, then manufacturing is simple, but paste spreads excessively causing bonding defects
Solution Approach 1:
A concave (curved downward) structure is introduced into the die pad surface at the bonding region. This curvature creates a natural containment for the metal paste, guiding it to spread only within the bonding region and preventing overflow onto the non-bonding region. The curved structure effectively suppresses bonding defects while adding minimal complexity to the die pad design
Data Source
AI summary
According to one embodiment, a semiconductor device includes a semiconductor chip, and a die pad. The die pad has a first surface. The semiconductor chip is bonded on the first surface using a paste including a metal particle. A concave structure is provided in the first surface. The concave structure is positioned directly under each of a plurality of sides of the semiconductor chip and extends along each of the plurality of sides.