Embedded Thin Film Capacitor Laser Lift-Off PCB
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Solution Overview
Problem
Conventional methods for embedding capacitors in printed circuit boards (PCBs) face challenges due to the high-temperature heat treatment required for dielectric materials, which can lead to oxidation of copper foils, resulting in decreased capacitance and poor dielectric properties.
Innovation Solution
A method involving the formation of a dielectric film on a transparent substrate, heat treatment, and subsequent laser lift-off to separate the substrate from the stack, allowing for the formation of conductive layers and insulating layers to create a thin film capacitor within the PCB without the need for high-temperature heat treatment, thereby preventing oxidation and maintaining superior dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature heat treatment (400-800°C) is applied to crystallize the dielectric film and achieve high dielectric constant, then the dielectric properties are improved, but the copper foil oxidizes resulting in decreased capacitance
Solution Approach 1:
A transparent substrate (sapphire, quartz, or glass) is introduced as an intermediary carrier for the dielectric film during high-temperature heat treatment. The substrate protects the copper foil from oxidation while allowing the dielectric film to be crystallized at 400-800°C to achieve high dielectric constant. After heat treatment, laser lift-off separates the dielectric film from the transparent substrate and transfers it to the copper foil, achieving both high dielectric properties and prevention of copper oxidation.
2Ease of manufacture
If conventional lamination method is used to embed capacitor, then the manufacturing process is simple, but the capacitor size is large and electrical properties at high frequency are poor
Solution Approach 1:
The invention changes the dimensional parameters of the capacitor by using thin film deposition techniques to create ultra-thin dielectric films (sub-micrometer to micrometer scale). This parameter change in film thickness enables the capacitor to achieve superior electrical properties at high frequencies while maintaining a compact size suitable for embedding in PCBs.
3Ease of manufacture
If dielectric film is deposited directly on copper foil and heat-treated, then the process is straightforward, but the copper foil oxidizes during heat treatment reducing capacitance
Solution Approach 1:
The manufacturing process is segmented into distinct stages: (1) depositing the dielectric film on a transparent substrate, (2) heat-treating the dielectric film on the substrate to achieve crystallinity without copper oxidation, (3) forming electrodes on the heat-treated dielectric film, (4) using laser lift-off to separate the dielectric film from the substrate, and (5) transferring the dielectric film to the copper foil. This segmentation allows high-temperature heat treatment to be performed on the substrate rather than directly on the copper foil, preventing oxidation while maintaining manufacturing feasibility.
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 effectively embeds thin film capacitors in PCBs with improved dielectric properties and capacitance, overcoming the limitations of conventional techniques by preventing oxidation and maintaining crystallinity of the dielectric film, even on copper foils.
Implementation Method 1
irradiating a laser beam onto a stack formed, from below the transparent substrate, to separate the transparent substrate from the stack
Data Source
AI summary
A method for manufacturing a printed circuit board with a capacitor embedded therein which has a dielectric film using laser lift off, and a capacitor manufactured thereby. In the method, a dielectric film is formed on a transparent substrate and heat-treated. A first conductive layer is formed on the heat-treated dielectric film. A laser beam is irradiated onto a stack formed, from below the transparent substrate, to separate the transparent substrate from the stack. After the transparent substrate is separated from the stack, a second conductive layer is formed with a predetermined pattern on the dielectric film. Also, an insulating layer and a third conductive layer are formed on the first and second conductive layers to alternate with each other in a predetermined number.