Multilayer Wiring Substrate with Printed Conductive Paste Electrodes
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Solution Overview
Problem
Existing multilayer wiring substrates face limitations in increasing wiring density due to formation errors and positioning issues between on-layer wiring conductors and via hole conductors, which are formed using different methods, leading to connection failures and reduced surface wiring density.
Innovation Solution
A multilayer wiring substrate with printed wiring electrodes formed by sintering conductive paste, where the second wiring electrode portion extends through a through hole in the first insulating layer and is exposed on the top surface, allowing for increased wiring density without the need for separate via hole conductors, thus reducing formation errors and enhancing flatness and manufacturing cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If on-layer wiring conductors and via hole conductors are formed by different methods, then connection between layers is achieved, but formation errors and positioning errors accumulate leading to connection failures
Solution Approach 1:
The patent merges the formation processes of on-layer wiring conductors and via hole conductors into a single screen printing step. Conductive paste is printed to form both the wiring conductor on the insulating layer surface and the via hole conductor extending through the insulating layer simultaneously, eliminating positioning errors between separately formed conductors
Solution Approach 2:
The wiring electrode is segmented into a first wiring electrode portion on the insulating layer surface and a second wiring electrode portion extending through the insulating layer, with both portions formed as an integrated structure through screen printing to ensure precise alignment
2Reliability
If the area of on-layer wiring conductor connected to via hole conductor is increased to prevent connection failures, then connection reliability improves, but wiring density in surface direction is suppressed
Solution Approach 1:
The patent extends the wiring electrode into the thickness direction of the insulating layer through the via hole, utilizing the third dimension (depth) to provide connection reliability without increasing the surface area, thereby maintaining high wiring density in the surface direction
3Reliability
If via hole conductor thickness is increased to prevent connection failures, then connection reliability improves, but wiring density increase is limited
Solution Approach 1:
The wiring electrode utilizes the thickness direction of the insulating layer to extend through the via hole, providing sufficient connection reliability through extended depth rather than increased lateral dimensions, thereby enabling higher wiring density
4Ease of manufacture
If multiple separate formation steps are used for on-layer wiring and via hole conductors, then manufacturing flexibility is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines the formation of on-layer wiring conductors and via hole conductors into a single screen printing and sintering step, reducing the number of manufacturing steps and simplifying the overall process while maintaining the ability to form complex conductor geometries
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 solution increases wiring density, reduces the risk of ceramic cracks and warping, and decreases manufacturing costs while maintaining electrical integrity and flatness of the substrate surface.
Implementation Method 1
a printed wiring electrode formed by printing with and sintering conductive paste
Data Source
AI summary
A multilayer wiring substrate that can realize a higher-density wiring structure is obtained. Provided is a multilayer wiring substrate, where a multilayer body including a first insulating layer and a second insulating layer stacked on the bottom surface of the first insulating layer includes printed wiring electrodes; the printed wiring electrodes are formed by printing with and sintering conductive paste; the printed wiring electrodes respectively include first wiring electrode portions located on the second insulating layer and second wiring electrode portions respectively joined to first wiring electrode portions; and the second wiring electrode portions respectively extend into through holes and, further, are exposed at the top surface of the first insulating layer.