Resin Multilayer Substrate With Recessed Conductor Pattern
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Solution Overview
Problem
The existing resin multilayer substrates face short-circuit failures due to the oozing of low-melting metals like Sn from conductive pastes used for interlayer-connection conductors during the stacking and pressure-bonding process of thermoplastic resin sheets, causing electrical continuity issues.
Innovation Solution
The solution involves designing a resin multilayer substrate with a conductor pattern having portions of different thicknesses, where the conductive paste with a low-melting metal is contained within a recessed area, preventing it from spreading and causing short-circuits, while ensuring metallization by incorporating a metallic foil like copper and forming intermetallic compounds to increase the melting point and reduce fluidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-melting metal such as Sn is added to a conductive paste to enable metallization of interlayer-connection conductors during stacking and pressure-bonding, then metallization becomes possible, but the low-melting metal oozes out and spreads over gaps between resin layers causing short-circuit failure
Solution Approach 1:
The conductor pattern is designed with a recessed portion that creates a localized containment area for the conductive paste. This local structural modification allows the paste to be held in a specific region where it can metallize the interlayer-connection conductor without spreading to adjacent areas, thus preventing short-circuit failures while maintaining effective metallization.
2Strength
If heat and pressure are applied for pressure-bonding resin sheets to form a multilayer substrate, then the resin layers are bonded together, but the low-melting metal in the conductive paste oozes out and spreads causing electrical continuity between conductor patterns
Solution Approach 1:
The recessed portion in the conductor pattern creates a localized containment structure that restricts the movement of oozed conductive paste during pressure-bonding. This local structural feature allows the application of heat and pressure for strong bonding while preventing the paste from spreading to adjacent conductor patterns, thus maintaining electrical integrity.
3Productivity
If the distance between adjacent conductor patterns is reduced to improve circuit density, then more conductors can be packed, but short-circuit failure becomes more likely due to oozed metal bridging the gaps
Solution Approach 1:
The recessed portion creates a localized containment area that physically restricts the spread of conductive paste even when conductor patterns are closely spaced. This allows for higher circuit density with reduced pitch between conductors while maintaining reliability by preventing paste migration that would cause short-circuits in high-density configurations.
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 configuration effectively prevents short-circuit failures by containing the oozed conductive paste and facilitates full metallization, resulting in a substrate with improved electrical integrity and high-frequency characteristics.
Implementation Method 1
when heat and pressure are applied for pressure-bonding a stack of a plurality of resin sheets, the low-melting metal oozes out of the conductive paste portion
Implementation Method 2
applying pressure to the stack while heating it to higher than or equal to the softening temperature of the thermoplastic resin
Implementation Method 3
a first conductor pattern at an area including a region in which the first interlayer-connection conductor is exposed at the surface of the first resin layer
Data Source
AI summary
A resin multilayer substrate includes a first resin layer including a thermoplastic resin as a main material, a second resin layer including the thermoplastic resin as a main material and superposed on the first resin layer, a first interlayer-connection conductor passing through the first resin layer in a thickness direction, and a first conductor pattern at an area including a region in which the first interlayer-connection conductor is exposed at the surface of the first resin layer between the first resin layer and the second resin layer. The first conductor pattern includes a portion in or at which a portion of the first interlayer-connection conductor is disposed. The first conductor pattern includes a first portion covering the region exposed at the surface of the first resin layer; and a second portion disposed surrounding the first portion. The first portion and the second portion have different thicknesses from each other.