Resilient Conductive Paste Post for Semiconductor Wire Bonding
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Solution Overview
Problem
The existing stacked multichip package technology faces challenges in forming reliable wire bonds on bond pads adjacent to the overhanging side edge of the second die, leading to stress-induced peeling between dies and reduced production yield.
Innovation Solution
The use of a conductive paste post printed on the bond pad, which serves as a buffer to prevent aluminum extrusion and reduce stress, along with a conductive trace and redistributed bond pad to enhance electrical connectivity, allowing for secure bonding wires and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is performed on bond pads adjacent to the overhanging side edge of the second die, then electrical connectivity is achieved, but stress-induced peeling occurs between dies reducing reliability
Solution Approach 1:
A conductive paste post is introduced as an intermediary element between the bond pad and the bonding wire. This paste post, composed of resilient conductive material, absorbs and distributes the stress from wire bonding, preventing stress-induced peeling between the first and second dies while maintaining electrical connectivity.
Solution Approach 2:
The patent changes the physical and material parameters of the bond pad structure by introducing a conductive paste post with different mechanical properties (resilience, compliance) compared to traditional rigid bond pads. This parameter change allows the structure to accommodate bonding stress without peeling.
2Productivity
If conventional wire bonding is used on stacked multichip packages, then production can proceed, but manufacturing precision is reduced due to difficulty in forming bonds adjacent to overhanging edges
Solution Approach 1:
The conductive paste post serves as a mediator that facilitates wire bonding in previously difficult-to-bond locations adjacent to overhanging edges. By providing a compliant bonding surface, it enables precise bond formation where conventional methods fail, thereby improving both manufacturing precision and production yield.
3Productivity
If bond pad openings are reduced to improve throughput, then manufacturing efficiency increases, but reliability may be compromised without proper stress management
Solution Approach 1:
The introduction of the conductive paste post changes the stress distribution parameters in the bond pad structure. This allows bond pad openings to be reduced for higher throughput while the paste post compensates for reduced structural support, maintaining reliability despite smaller bonding areas.
Data Source
AI summary
A semiconductor chip package includes a substrate; a semiconductor die mounted on the substrate, wherein the semiconductor die comprises a bond pad disposed on an active surface of the semiconductor die, and a passivation layer covering perimeter of the bond pad, wherein a bond pad opening in the passivation layer exposes a central area of the bond pad; a conductive paste post printed on the exposed central area of the bond pad; and a bonding wire secured to a top surface of the conductive paste post. The conductive paste post comprises copper paste.