Bifunctional Organic Adhesion Layer for Polymer-Copper Interfaces
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Solution Overview
Problem
Current methods for improving adhesion between polymer films and copper interconnects in electronic devices often result in poor adhesion leading to delamination, which complicates device reliability and can lead to signal bandwidth loss when increasing surface roughness is used to address the issue.
Innovation Solution
A bifunctional organic compound is applied to form an adhesion layer on copper pads, with one functional group reactive with copper and the other non-reactive, followed by a resin layer deposition and curing, and then partial removal of the resin layer to expose the copper pad, enhancing adhesion without increasing surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface roughness of copper is increased to improve adhesion between polymer films and copper interconnects, then adhesion strength is improved, but signal bandwidth is lost
Solution Approach 1:
A self-assembled monolayer (SAM) formed from bifunctional organic compounds acts as an intermediary between the copper interconnect and polymer film. One functional group of the compound binds to copper surface atoms while the other functional group interacts with the polymer, creating a molecular bridge that enhances adhesion without modifying the copper surface roughness, thereby preserving signal bandwidth
Solution Approach 2:
The invention changes the chemical parameter of the copper surface by forming a molecular monolayer with specific functional groups, rather than changing the physical parameter of surface roughness. This chemical modification provides enhanced adhesion through molecular interactions while maintaining the original surface topology that supports high-frequency signals
2Device complexity
If polymeric materials are bonded directly to metal contacts, then device assembly is simplified, but adhesion failure occurs leading to delamination
Solution Approach 1:
The bifunctional organic compound forms a self-assembled monolayer that serves as a molecular intermediary between the metal contact and polymeric material. This intermediary layer ensures reliable adhesion by providing chemical compatibility with both surfaces, preventing delamination while adding minimal complexity to the bonding process
Solution Approach 2:
The invention creates a composite interface structure consisting of the metal contact, the organic compound monolayer, and the polymeric material. This multi-layer composite structure combines the advantages of direct bonding with enhanced adhesion, as the organic layer acts as a transition zone that bonds effectively to both the metal and polymer
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 method improves adhesion between polymer films and copper pads, preventing delamination and maintaining signal integrity by forming a robust interface without compromising copper surface roughness.
Implementation Method 1
A substrate with a copper pad and a dielectric surface is exposed to a bifunctional organic compound to form an adhesion layer on the copper pad. The bifunctional organic compound has two different functional groups; one of the functional groups is reactive with the copper pad
Implementation Method 2
the resin layer is then cured
Implementation Method 3
A portion of the resin layer over the copper pad is removed by laser ablation to expose the copper pad through the resin layer
Data Source
AI summary
Methods for forming circuit boards and circuit boards using an adhesion layer are described. A substrate with two surfaces is exposed to a bifunctional organic compound to form an adhesion layer on the first substrate surface. A resin layer is then deposited on the adhesion layer and the exposed substrate surfaces. Portions of the resin layer may be removed to expose metal pads for contacts.