Plated Bond Wire Portion for IC Lead Adhesion
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Solution Overview
Problem
Integrated circuit packages face delamination issues between the encapsulating material and silver-coated lead tips due to poor adhesion, leading to wire bond failures, especially under temperature changes, and replacing gold wires with copper worsens this problem.
Innovation Solution
The integration of a plated bond wire portion made of copper with a silver plating between the unplated proximal and distal ends of the leads, which are covered by an encapsulation material, providing a robust adhesion surface without the need for additional lead size or costly silver plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lead tips are coated with silver to promote wire bonding, then wire bonding is facilitated, but delamination occurs between the molding compound and silver coating causing wire bond failure
Solution Approach 1:
The lead is designed with different materials at different locations: copper at the distal end for molding compound adhesion, silver plating only at the bond wire attachment point for wire bonding, and copper again at the proximal end. This local differentiation allows each section to perform its specific function optimally without causing delamination.
Solution Approach 2:
The copper proximal end acts as an intermediary between the silver-coated bond wire attachment point and the molding compound. This copper section provides a transition zone that ensures proper adhesion to the molding compound while supporting the silver-plated section for wire bonding, preventing direct contact between the molding compound and silver that causes delamination.
2Ease of manufacture
If gold wire is replaced with copper wire for cost saving, then manufacturing cost is reduced, but the chance of lead tip delamination increases and wire bond failure becomes more severe
Solution Approach 1:
The lead structure uses copper at the distal end for cost-effectiveness and molding compound adhesion, while applying silver plating only at the specific location where wire bonding occurs. This localized silver plating maintains wire bonding reliability with copper wire by providing the necessary bonding surface without requiring full silver coating or gold wire.
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 configuration enhances the mechanical locking and adhesion between the bond wires and the encapsulation material, reducing delamination and wire bond failures while maintaining cost-effectiveness by using copper for the bond wires and silver plating only where necessary.
Implementation Method 1
enhances the mechanical locking and adhesion between the bond wires and the encapsulation material
Data Source
AI summary
An integrated circuit (IC) device includes an IC die and a plurality of leads. Each lead includes an unplated proximal end including a first material, and an unplated distal end including the first material. A plated bond wire portion extends between the proximal and distal ends and includes the first material and a plating of a second material thereon. A plurality of bond wires extend between the IC die and the plated bond wire portions of the leads. An encapsulation material surrounds the IC die and bond wires so that the unplated proximal end and plated bond wire portion of each lead are covered by the encapsulation material.