Composite Filter Bond Height Tuning for Attenuation Control
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Solution Overview
Problem
Attenuation characteristics in composite filter devices degrade due to varying parasitic inductance values between filter chips mounted on a common substrate, particularly in filter chips with longitudinally coupled resonator filters.
Innovation Solution
The composite filter device employs different height conductive bonds for filter chips, with lower bonds for longitudinally coupled resonator filters and higher bonds for ladder filters, to manage parasitic inductance and improve attenuation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heights of bumps are made to be the same for all filter chips, then manufacturing is easier, but attenuation characteristics in filter chips with longitudinally coupled resonator filters may degrade
Solution Approach 1:
The patent applies local quality by differentiating the bump heights based on the specific filter chip type. Filter chips with longitudinally coupled resonator filters use first bumps with a first height, while other filter chips use second bumps with a second height. This localized differentiation ensures that each filter chip type receives the appropriate parasitic inductance value needed for optimal attenuation characteristics, rather than applying a uniform bump height to all chips.
2Reliability
If different height bumps are used for different filter chips, then attenuation characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements parameter changes by varying the height parameter of the bumps based on the filter chip type. By changing this single geometric parameter (bump height) rather than introducing entirely different bonding structures, the patent achieves the desired parasitic inductance differentiation while maintaining relatively simple manufacturing processes. The substrate includes multiple bonding regions with different bump height parameters, allowing precise control over parasitic inductance for each filter chip type.
3Reliability
If bump heights are differentiated by filter chip type, then parasitic inductance values are optimized, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the substrate with multiple bonding regions that have predetermined different bump heights. The substrate is designed in advance with first bonding regions for filter chips with longitudinally coupled resonator filters and second bonding regions for other filter chips. This preliminary configuration of the substrate structure allows the bump height differentiation to be built into the manufacturing process itself, reducing the need for post-assembly adjustments and simplifying quality control.
Data Source
AI summary
A composite filter device includes first and second filter chips mounted on an upper surface of a substrate by first and second conductive bonds. The first filter chip includes a longitudinally coupled resonator filter. The second filter chip does not include a longitudinally coupled resonator filter. A height of the first conductive bond is lower than a height of the second conductive bond.