Staircase Die Stack Wire Bonding for Stronger Pad Adhesion
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Solution Overview
Problem
Existing semiconductor packages face challenges in efficiently connecting multiple semiconductor dies to a printed circuit board, particularly in miniaturized and lightweight electronic devices, where traditional bonding methods may lead to reduced adhesive strength and reliability.
Innovation Solution
A semiconductor package design featuring a semiconductor die stack in a staircase shape with a wiring structure and conductive pads that include stepped or recessed surfaces to enhance bonding wire connectivity, utilizing bonding wires with protrusion portions and surface roughness to increase adhesive strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bonding methods are used to connect semiconductor dies to printed circuit board, then the connection is simple, but the adhesive strength and reliability are reduced
Solution Approach 1:
The bonding wire is designed with a protrusion portion at specific locations to create localized contact points with the conductive pad. This local quality enhancement at the bonding interface increases adhesive strength without requiring changes to the entire wire structure or bonding process
Solution Approach 2:
The protrusion portion of the bonding wire creates a curved or non-linear contact surface with the conductive pad. This curvature increases the contact surface area and improves mechanical interlocking, thereby enhancing adhesive strength and reliability
2Use of energy by moving object
If bonding wire length is reduced to improve power efficiency and heat dissipation, then power efficiency and heat dissipation are enhanced, but connection reliability may be compromised
Solution Approach 1:
The protrusion portion creates an optimized wire path with controlled curvature that reduces overall wire length while maintaining adequate mechanical strength. The curved contact surface at the protrusion portion compensates for the reduced length by improving contact quality
Solution Approach 2:
The protrusion portion concentrates the bonding function at specific locations along the wire, creating strong localized connections that compensate for the reduced overall wire length. This local enhancement ensures connection reliability is maintained despite shorter wire length
3Reliability
If conductive pads are designed with stepped or recessed surfaces to enhance bonding wire connectivity, then adhesive strength is increased, but manufacturing complexity increases
Solution Approach 1:
The stepped or recessed surface structure creates localized contact zones on the conductive pad where the bonding wire protrusion portion makes contact. This local quality enhancement improves bonding reliability without requiring the entire pad surface to be precisely formed
Solution Approach 2:
The conductive pad surface is segmented into different levels or zones (stepped structure), creating distinct contact areas for the bonding wire. This segmentation allows for easier manufacturing by defining specific contact zones rather than requiring uniform precision across the entire pad surface
Data Source
AI summary
A semiconductor package includes a semiconductor die stack stacked in a staircase shape; a wiring structure facing one surface of the semiconductor die stack, the wiring structure including a conductive pad facing the semiconductor die stack; and a bonding wire connecting the semiconductor die stack to the conductive pad. The wiring structure includes a wiring structure upper surface facing the one surface of the semiconductor die stack, and a wiring structure lower surface that is opposite the wiring structure upper surface, and the wiring structure upper surface extends along a virtual plane. The conductive pad includes a conductive pad surface facing the one surface of the semiconductor die stack. The conductive pad surface is separated from the virtual plane.