Embedded Base Metal Structure for Flexible Substrate Adhesion
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Solution Overview
Problem
Traditional flexible multi-layer substrates face issues with delamination and separation of metal layers from dielectric layers as the substrate thickness decreases, leading to lower manufacturing yield and reliability, especially when subjected to bending forces.
Innovation Solution
A metal structure with an embedded base and main body, where the base area is larger than the main body, is formed using photolithography and physical vapor deposition, allowing for improved adhesion and connection with dielectric layers, preventing delamination and enhancing reliability even at thinner thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the flexible multi-layer substrate is reduced to achieve miniaturization, then the routing density increases and product size decreases, but the metal layer becomes thinner and more prone to delamination and separation
Solution Approach 1:
The metal layer is segmented into two distinct parts: an embedded base portion that anchors into the dielectric layer and a main body portion that provides the conductive function. This segmentation allows the embedded base to provide strong adhesion while the main body maintains the required electrical connectivity, resolving the contradiction between thin substrate design and reliable metal layer attachment.
Solution Approach 2:
Different regions of the metal layer are given different functional qualities: the embedded base portion is designed for maximum adhesion strength and mechanical anchoring, while the main body portion is optimized for electrical conductivity and routing functionality. This local differentiation of quality allows the thin substrate to maintain both reliability and miniaturization benefits.
2Volume of moving object
If the metal layer thickness is reduced to enable thinner substrate, then manufacturing precision requirements increase and delamination risk increases, but productivity decreases due to lower manufacturing yield
Solution Approach 1:
The embedded base portion is formed first and anchored into the dielectric layer before the main body portion is deposited. This preliminary action ensures that the adhesion-critical portion is established with proper mechanical interlocking before subsequent processing steps, thereby improving manufacturing yield even as overall layer thickness is reduced.
3Stability of the object's composition
If the metal layer is made thinner for constant bending devices, then flexibility improves, but the metal layer strips off from solder ball mounts due to bending forces
Solution Approach 1:
The metal layer transitions from a simple planar structure to a three-dimensional structure with the embedded base portion extending vertically into the dielectric layer. This dimensional change provides additional anchoring volume and surface area for adhesion, maintaining bonding strength even as the overall metal layer thickness is reduced for flexibility.
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 metal structure achieves higher reliability and prevents delamination, enabling the use of thinner flexible multi-layer substrates in constantly bent devices with improved bonding strength and manufacturing yield.
Implementation Method 1
proceeding a photolithography process to the photoresist layer to define a specific position for a first metal layer
Implementation Method 2
forming the first metal layer at the specific position
Data Source
AI summary
A metal structure manufacture method for a multi-layer substrate comprises coating a photoresist layer on a first dielectric layer; proceeding a photolithography process to the photoresist layer to define a specific position for a first metal layer; removing the photoresist layer at the specific position; and forming the first metal layer at the specific position, wherein a base area of the first metal layer is larger than a top area thereof, and wherein the embedded base and the main body are formed in a same process and are monolithic formed. Said manufacturing method can be employed to manufacture a pad or a metal line of the flexible multi-layer substrate, and the manufactured metal structure cannot easily be delaminated or separated from the contacted dielectric layer.