Conductive Paste Wiring for Printed Wiring Boards
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Solution Overview
Problem
Conductive pastes used in printed wiring boards have high electrical resistance values, making it difficult to achieve stable circuit quality for long and narrow wiring applications, particularly in vehicles, where low resistance is required to handle high currents.
Innovation Solution
A method involving a conductive paste with metal nanoparticles and metal particles, a thermosetting resin with an oxirane ring, and a cellulose resin is applied to a substrate, resulting in a printed wiring board with a length of 100 mm to 1600 mm, a width of 0.3 mm to 3 mm, and a thickness of 10 µm to 40 µm, with a resistance value of 1000 mΩ/m or less, enhancing conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a general resin component is used in conductive paste to enable wiring adhesion to substrate, then adhesion is improved, but electrical resistance increases significantly
Solution Approach 1:
The patent changes the chemical structure parameters of the resin component by specifying epoxy resin with particular molecular weight ranges (300-1000 for main agent, 100-500 for crosslinking agent) to achieve optimal balance between adhesion and electrical resistance. This parameter optimization allows the resin to provide sufficient bonding strength while maintaining lower electrical resistance compared to general resin components.
Solution Approach 2:
The patent creates a composite conductive paste formulation combining metal particles, epoxy resin main agent, crosslinking agent, and optional additives in specific proportion ranges. This composite structure integrates the adhesive properties of epoxy resin with the conductive properties of metal particles, achieving both good adhesion and acceptable electrical resistance that neither component could achieve alone.
2Strength
If conductive paste with resin component is used to form wiring, then adhesion to substrate is achieved, but resistance value becomes several to several tens of times larger than copper foil
Solution Approach 1:
The patent optimizes the molecular weight parameters of the epoxy resin components and their proportion in the conductive paste to minimize resistance. By specifying narrow molecular weight ranges and proportion ranges, the invention achieves resistance values at the lower end of the inherent trade-off, making the wiring suitable for high current applications where general conductive pastes would fail.
3Length of moving object
If long and narrow wiring is formed with conventional conductive paste, then wiring length is achieved, but stable circuit quality cannot be obtained due to high resistance
Solution Approach 1:
The patent changes the electrical parameters of the conductive paste by optimizing metal particle content, epoxy resin molecular weight, and crosslinking agent proportion. These parameter changes reduce the specific resistance of the cured wiring, enabling long wiring (100-1600mm) to maintain acceptable resistance values (1000mΩ/m or less) and achieve stable circuit quality for high current applications.
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 method enables the production of printed wiring boards capable of handling high currents with reduced resistance values, suitable for long and narrow wiring applications, particularly in vehicle sensor modules, ensuring stable circuit quality and heat management.
Implementation Method 1
curing the applied conductive paste to form wiring
Implementation Method 2
a thermosetting resin having an oxirane ring in a molecule
Data Source
Figure 1
Figure 2~3
AI summary
A printed wiring board 10 includes a substrate 11 and wiring 12 provided on a surface of the substrate and including a cured conductive paste. The conductive paste contains metal nanoparticles having an average particle diameter of 30 nm or more and 600 nm or less, metal particles having an average particle diameter larger than that of the metal nanoparticles, a thermosetting resin having an oxirane ring in a molecule, a curing agent, and a cellulose resin. The wiring has a length of 100 mm or more and 1600 mm or less, a width of 0.3 mm or more and 3 mm or less, a thickness of 10 µm or more and 40 µm or less, and a resistance value of 1000 mΩ/m or less.