Multilayer Wiring Board Interlayer Connection via Intermetallic Compound Layers
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Solution Overview
Problem
Multilayer wiring boards face delamination issues due to residual solvent in interlayer connection conductors, leading to breakage during heat treatment, as the vaporized solvent causes gas expansion and stress at the interface between insulating and conductive layers.
Innovation Solution
Incorporating intermetallic compound layers with different compositions on either side of the interlayer connection conductor, positioned at varying levels relative to the interface between conductive wiring and insulating layers, and using a thermoplastic resin with a projection to disperse stress, along with a conductive paste containing metal powders that react to form intermetallic compounds, thereby enhancing bonding strength and reducing delamination risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conductive paste containing solvent is used to form interlayer connection conductor, then filling properties are improved, but residual solvent causes delamination and breakage during heat treatment
Solution Approach 1:
The patent applies preliminary action by completely removing the solvent from the conductive paste through drying treatment before subsequent heat treatment processes. This prevents the solvent from vaporizing during reflow soldering, thereby eliminating the cause of delamination and interlayer connection conductor breakage while maintaining the filling properties provided by the solvent during the formation process
Solution Approach 2:
The patent converts the harmful effect of residual solvent (which causes delamination and breakage) into a beneficial process by implementing controlled drying treatment. The solvent's presence during filling is utilized for its flowability benefits, then systematically removed through drying, transforming the potential harm into a controlled process step that ensures reliability
2Ease of manufacture
If heat treatment is applied to remove solvent, then filling properties are maintained, but vaporized solvent causes gas expansion and delamination
Solution Approach 1:
The patent performs solvent removal as a preliminary action before the heat treatment that would cause solvent vaporization. By completing the drying process prior to reflow soldering, the patent eliminates the source of gas expansion and delamination while preserving the benefits of solvent-based filling
3Reliability
If drying treatment is extended to completely remove solvent, then delamination is prevented, but manufacturing time increases
Solution Approach 1:
The patent applies parameter changes by optimizing the drying treatment conditions (temperature, time, atmosphere) to achieve complete solvent removal within a reasonable time frame. By carefully controlling these parameters, the patent balances the need for thorough solvent elimination with manufacturing efficiency, preventing delamination without excessive time loss
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 effectively disperses delamination stress, preventing breakage of interlayer connection conductors by positioning intermetallic compound layers away from the weakest interface points and increasing bonding strength between layers, thus enhancing the reliability of multilayer wiring boards.
Implementation Method 1
a conductive paste containing metal powders that react to form intermetallic compounds
Implementation Method 2
Incorporating intermetallic compound layers with different compositions on either side of the interlayer connection conductor, positioned at varying levels relative to the interface between conductive wiring and insulating layers, and using a thermoplastic resin with a projection to disperse stress
Data Source
AI summary
A multilayer wiring board includes first and second insulating layers, a first conductive wiring layer on the first insulating layer, a second conductive wiring layer on a surface of the second insulating layer facing the first insulating layer, an interlayer connection conductor including an intermetallic compound and penetrating through the first insulating layer to interconnect the first and second conductive wiring layers, a first intermetallic compound layer between the first conductive wiring layer and the interlayer connection conductor, and a second intermetallic compound layer between the second conductive wiring layer and the interlayer connection conductor, wherein the intermetallic compounds in the first and second intermetallic compound layers have a composition different from that of the intermetallic compound in the interlayer connection conductor, and the first intermetallic compound layer is located at a level different from a level of an interface between the first conductive wiring layer and the first insulating layer.