Semiconductor Package RDL Interface With Conductive Adhesive Layer
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Solution Overview
Problem
Existing semiconductor package structures face issues with delamination between conductive pads and metal layers, such as redistribution layers, due to inadequate adhesion during bonding processes with external circuitry like printed circuit boards.
Innovation Solution
A conductive adhesive layer is formed between the conductive pads and the redistribution layer, enhancing the contact area and adhesion strength between the conductive pads and the adhesive layer, which is stronger than the adhesion between the pads and the redistribution layer, thereby preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer (such as Cu redistribution layer) is directly bonded to a conductive pad through solder balls, then electrical connection is achieved, but bonding stress causes delamination between the metal layer and the conductive pad
Solution Approach 1:
An adhesive layer is introduced as an intermediary component between the conductive pad and the metal redistribution layer. This adhesive layer serves as a mediator that transfers and distributes bonding stress, preventing direct stress concentration at the pad-metal interface that would cause delamination. The adhesive layer chemically bonds to both the conductive pad and metal layer, creating a stable intermediate bonding interface.
Solution Approach 2:
The bonding structure transitions from a simple two-layer interface (conductive pad directly to metal layer) to a composite three-layer structure (conductive pad + adhesive layer + metal layer). This composite structure combines the electrical conductivity of the pad and metal layer with the stress-distribution properties of the adhesive layer, achieving both electrical connection and mechanical stress resistance.
2Adaptability or versatility
If external circuitry is bonded to the semiconductor package, then electrical functionality is enabled, but bonding stress causes delamination at the metal layer interface
Solution Approach 1:
The adhesive layer acts as a mediator that enables external circuitry integration while protecting the underlying conductive pad-metal layer interface from bonding stress. It provides a compliant bonding surface for external circuitry attachment while distributing stresses away from the critical pad interface.
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
The use of a conductive adhesive layer improves the reliability of semiconductor package structures by ensuring strong adhesion between components, reducing the likelihood of delamination and enhancing the structural integrity during packaging and bonding processes.
Implementation Method 1
enhancing the contact area and adhesion strength between the conductive pads and the adhesive layer
Data Source
AI summary
A semiconductor package structure includes a semiconductor substrate, a conductive pad on the semiconductor substrate, and a passivation layer on the semiconductor substrate and the conductive pad. The passivation layer exposes a portion of the top surface of the conductive pad. The semiconductor package structure also includes a conductive adhesive layer on the conductive pad, and a dielectric layer on the passivation layer and the conductive adhesive layer. The dielectric layer exposes a portion of the conductive adhesive layer. The semiconductor package structure also includes a redistribution layer (RDL) structure on the dielectric layer and electrically connected to the conductive pad through the conductive adhesive layer. The semiconductor package structure also includes a bump structure over the RDL structure.