Thin-Film Capacitor Terminal Layout for Wire Bonding Integrity
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Solution Overview
Problem
Thin film capacitors are vulnerable to mechanical damage during wire bonding due to their reduced height and thickness, which can lead to cracks and reduced adhesion strength when exposed to ultrasonic waves, compromising their performance in high-speed IC operations.
Innovation Solution
A thin film capacitor design featuring a capacitor part with a lower electrode, inner electrode, and dielectric layer, covered by an insulating layer with via holes connecting the terminal electrode to the inner electrode, and a ring-shaped via region with a flat bonding region to enhance adhesion strength and reduce damage during wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thin film capacitor is connected to a circuit board using a bonding wire with normal ultrasonic wave intensity, then adhesion strength of the bonding wire is maintained, but the thin film capacitor suffers mechanical damage such as cracks and peeling due to its reduced height and thickness
Solution Approach 1:
The terminal electrode is divided into two functional regions: a via region with a larger area for distributing ultrasonic energy during wire bonding, and a bonding region with a flat surface for optimal wire adhesion. This segmentation allows the via region to absorb mechanical stress while the bonding region maintains strong wire attachment, resolving the contradiction between adhesion strength and structural integrity.
2Reliability
If the intensity of ultrasonic wave is reduced to protect the thin film capacitor from mechanical damage, then cracks and peeling are avoided, but adhesion strength of the bonding wire is lowered
Solution Approach 1:
By segmenting the terminal electrode into via and bonding regions, the via region with larger area can handle higher ultrasonic intensity for reliable wire bonding, while the bonding region provides a protected flat surface for wire attachment. This allows normal ultrasonic wave intensity to be used without causing damage to the capacitor body.
Solution Approach 2:
The via region acts as an intermediary structure that absorbs and distributes the mechanical stress from ultrasonic waves, protecting the vulnerable capacitor body while still enabling effective wire bonding. The via region with its larger area serves as a stress buffer between the wire bonding process and the capacitor internal structure.
3Area of stationary object
If the terminal electrode area is reduced to minimize the capacitor footprint, then the capacitor size is reduced, but the bonding region becomes insufficient for maintaining high adhesion strength
Solution Approach 1:
The terminal electrode is segmented into via and bonding regions, where the via region has a larger area for stress distribution and the bonding region has an optimized flat area for wire adhesion. This segmentation allows the capacitor to maintain a compact footprint while ensuring sufficient bonding area for strong wire attachment.
Solution Approach 2:
Different regions of the terminal electrode are given different qualities: the via region has a larger area for mechanical stress handling, while the bonding region has a flat surface optimized for wire adhesion. This local differentiation allows each region to perform its specific function optimally within the constrained overall footprint.
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 design effectively reduces damage to the internal structure of the thin film capacitor and maintains high adhesion strength with the bonding wire, ensuring reliable performance even under mechanical stress.
Implementation Method 1
a plurality of via holes penetrating the insulating layer so that the terminal electrode and the inner electrode of the capacitor part are connected to each other via the plurality of via holes
Implementation Method 2
a capacitor part having a lower electrode, an inner electrode, and a dielectric layer positioned between the lower electrode and the inner electrode
Data Source
AI summary
Disclosed herein is a thin film capacitor that includes a capacitor part having a lower electrode, an inner electrode, and a dielectric layer positioned between the lower electrode and the inner electrode, an insulating layer covering the capacitor part, a terminal electrode provided on the insulating layer, and a plurality of via holes penetrating the insulating layer so that the terminal electrode and the inner electrode of the capacitor part are connected to each other via the plurality of via holes. The terminal electrode includes a via region on which the plurality of via holes are arranged and having a ring-shaped, and a bonding region surrounded by the via region and having flat-shaped.