Embedded Ceramic Thin Films for PCB Reliability
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Solution Overview
Problem
Existing methods for embedding passive components in printed circuit boards (PCBs) face challenges such as corrosive electrochemical processes that lead to suboptimal device properties and energy inefficiency, particularly due to hydrolysis and corrosion of conductive surfaces like copper.
Innovation Solution
An electrochemical process is developed to coat conductive surfaces with ceramic or low solubility metal salts, forming porous ceramic thin films with tunable dielectric properties, which avoids corrosive conditions and reduces hydrogen generation, using a three-ply system with a top copper layer, an intermediate dielectric or semiconductor layer, and a bottom copper layer, and employing hydrogen peroxide to prevent copper corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrochemical process is used to form protective coating on conductive surface, then coating formation is achieved, but corrosion of copper and energy inefficiency occur due to hydrolysis
Solution Approach 1:
The patent introduces an intermediary substance (metal salt solution containing copper ions) that mediates between the electrochemical deposition process and the copper substrate. This intermediary layer prevents direct contact between corrosive hydroxide ions and the copper substrate, thereby preventing corrosion while allowing the protective coating to form. The intermediary metal salt solution acts as a buffer that controls the electrochemical reactions.
Solution Approach 2:
The patent changes the chemical parameters of the electrochemical process by controlling pH, ion concentration, and deposition voltage. By adjusting these parameters, the process forms a protective non-conductive coating that prevents further corrosion while maintaining energy efficiency. The parameter control ensures that hydrolysis is minimized and corrosion is prevented.
2Reliability
If electrochemical process is used to deposit film, then film formation is achieved, but hydrogen generation and energy inefficiency occur
Solution Approach 1:
The patent converts the harmful effect of hydrogen generation into a beneficial process by controlling the electrochemical reactions to deposit metal salt crystals directly onto the conductive surface. The hydrogen that would normally be generated as a byproduct is instead utilized to reduce metal ions in the solution, forming the desired protective coating. This transforms the harmful hydrogen evolution into a useful deposition mechanism.
3Reliability
If conventional chip resistors or capacitors are mounted on PCB surface, then component functionality is achieved, but size and parasitic effects increase
Solution Approach 1:
The patent embeds the passive components directly into the PCB structure by forming dielectric and conductive layers within the internal layers of the PCB. This nesting approach places the functional elements inside the PCB substrate rather than on the surface, achieving size reduction while maintaining functionality. The embedded structure eliminates the need for separate surface-mounted components.
Solution Approach 2:
The patent merges the fabrication of passive components with the PCB manufacturing process itself. By forming dielectric layers, conductive patterns, and component structures in the same manufacturing flow, the patent eliminates the need for separate component assembly steps. This combining of processes reduces overall device volume and eliminates parasitic effects associated with surface-mounted components.
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 process enables the formation of high-capacity ceramic films with improved dielectric performance, low processing temperatures, and micro-patterning capabilities, replacing discrete surface-mounted components and reducing parasitic effects, while maintaining high voltage withstandability and energy efficiency.
Implementation Method 1
employing hydrogen peroxide to prevent copper corrosion
Implementation Method 2
An electrochemical process is developed to coat conductive surfaces with ceramic or low solubility metal salts
Implementation Method 3
employing hydrogen peroxide to prevent copper corrosion
Data Source
AI summary
A method for forming a film on a conductive substrate, comprising immersing a substrate having a conductive portion in a solution comprising a metal ion ceramic precursor for the film and a peroxide; applying a voltage potential to the conductive portion with respect to a counter electrode in the solution, sufficient to protect the conductive portion from corrosion by the solution, and drive formation of a film on the substrate, controlling a pH of the solution while limiting a production of hydrogen by electrolysis of the solution proximate to the conductive portion; and maintaining the voltage potential for a sufficient duration to produce a film on the conductive portion. An electrode may be formed over the film to produce an electrical device. The film may be, for example, insulating, dielectric, resistive, semiconductive, magnetic, or ferromagnetic.