Circuit Board Through Conductor Thermal Stress Management
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Solution Overview
Problem
Circuit boards used in electronic devices experience cracking and separation due to thermal cycling, leading to poor heat dissipation and reduced performance over time, as the metallic wiring layers and through conductors expand and contract with temperature changes.
Innovation Solution
A circuit board design featuring a through conductor with a Sn-Ag alloy or Cu-containing oxide/Ni-containing oxide compound between the metallic wiring layers and through conductor, which applies compressive stress to prevent crack propagation and enhance heat dissipation, using Ag, Au, or Cu as major constituents for improved adhesion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal cycling occurs with wide temperature differences, then heat dissipation is improved, but cracking and separation occur in the base body, metallic wiring layer, and through conductor
Solution Approach 1:
The patent changes the physical-chemical state of the interface by forming an intermetallic compound layer through controlled thermal processing. This layer has different thermal expansion characteristics than the original materials, reducing stress during thermal cycling and preventing cracking while maintaining heat dissipation effectiveness.
Solution Approach 2:
The patent creates a composite structure at the interface between the through conductor and metallic wiring layer by forming an intermetallic compound layer. This composite interface combines the thermal conductivity of the through conductor with the adhesion properties of the compound layer, resolving the contradiction between heat dissipation and structural integrity under thermal stress.
2Loss of energy
If thermal cycling causes expansion and contraction, then heat transmission is maintained, but neighboring portions are prone to cracking or separation
Solution Approach 1:
The intermetallic compound layer acts as an intermediary between the through conductor and metallic wiring layer. It mediates the thermal and mechanical stress during cycling, absorbing expansion and contraction forces while maintaining continuous heat transmission path, thus preventing cracking without compromising thermal conductivity.
3Power
If electronic component sophistication increases, then performance capability is improved, but heat applied per unit area to metallic wiring layer increases
Solution Approach 1:
The patent modifies the thermal properties of the wiring structure by introducing the intermetallic compound layer, which has optimized thermal conductivity and heat capacity characteristics. This allows the system to handle higher heat flux from sophisticated electronic components without causing thermal damage or excessive temperature rise.
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 circuit board effectively withstands long-term thermal cycling, maintaining excellent heat-dissipation characteristics and ensuring the electronic component's performance over a prolonged period with reduced cracking and increased reliability.
Implementation Method 1
A circuit board according to the invention comprises: a base body (1) provided with a through hole penetrating therethrough from one principal face (1a) to the other principal face (1b) of the base body (1); a through conductor (2) located inside the through hole of the base body (1); and metallic wiring layers (3) disposed on respective principal faces (1a and 1b) of the base body (1). A compound containing at least one substance selected from Sn, Cu, and Ni is present between the through conductor (2) and the metallic wiring layer (3).
Implementation Method 2
there is a demand for a circuit board which allows efficient transmission of heat produced during operation of an electronic component from a metallic wiring layer disposed on one of board's principal faces on which the electronic component is mounted to another metallic wiring layer disposed on the other principal face via a through conductor
Data Source
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AI summary
There are provided a circuit board which has excellent heat-dissipation characteristics and is usable for a long period of time, and an electronic device in which an electronic component is mounted on the circuit board. A circuit board includes: a base body formed of ceramics or sapphire, the base body being provided with a through hole which penetrates therethrough from one principal face to another principal face of the base body; a through conductor containing silver as a major constituent, the through conductor being located inside the through hole of the base body; metallic wiring layers located on the respective principal faces of the base body and on the through conductor; and regions in which a compound containing at least one substance selected from Sn, Cu, and Ni is present between the through conductor and the metallic wiring layers.