Conductive Circuit Pattern Formation Using Copper and Solder Paste
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Solution Overview
Problem
Forming complex micro circuit patterns using photomasks is limited, and traditional methods involving precious metals like Au or Ag are costly due to their high expense.
Innovation Solution
A composition comprising Cu powders, a solder (such as Sn, Bi, In, Ag, Pb, or Cu), a polymer resin, a curing agent, and a reductant, which is printed on a substrate and optionally electrolytic-plated to form a conductive circuit pattern, reducing costs while maintaining high conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photomask is used to form circuit pattern, then manufacturing precision is improved, but device complexity increases and productivity decreases
Solution Approach 1:
The patent extracts the photomask step from the conventional printing process by using a self-aligning dual-curing mechanism. The first curing creates a temporary structure that guides the second curing, eliminating the need for external photomask alignment while maintaining precision.
Solution Approach 2:
The composition performs self-alignment through its dual-curing mechanism where the first cured layer automatically serves as the alignment template for the second curing step, making the system self-aligning without external equipment.
2Reliability
If precious metals (Au or Ag) are used in paste, then conductivity is improved, but cost increases
Solution Approach 1:
The patent replaces expensive precious metals with inexpensive Cu powder that is sacrificially consumed during the printing process. The Cu powder serves its导电 function temporarily during formation and is later replaced by solder during reflow, eliminating the need for durable precious metal conductors.
Solution Approach 2:
The patent creates a composite system combining Cu powder (for initial conductivity and self-aligning function), solder particles (for final durable conductivity), polymer resin (for structure), and reductant (for Cu oxidation control). This composite achieves both low cost and high conductivity.
3Quantity of substance
If Cu powder is used instead of precious metals, then cost is reduced, but electrical coupling deteriorates
Solution Approach 1:
The patent applies preliminary action by first forming a Cu powder pattern that provides initial conductivity and self-alignment, then subsequently applying solder that permanently replaces Cu for electrical coupling. The Cu powder's preliminary function enables the final superior electrical coupling.
Solution Approach 2:
The patent changes the electrical coupling parameter through the reflow process where solder melts and forms metallurgical bonds, transforming the electrical coupling from weak Cu-to-Cu contact to strong solder-to-substrate and solder-to-Cu bonds with superior conductivity.
4Reliability
If solder is added to enhance electrical coupling, then conductivity is improved, but composition complexity increases
Solution Approach 1:
The patent merges multiple functions into the single paste composition: Cu powder provides initial conductivity and self-alignment, solder provides final durable conductivity, polymer resin provides structural integrity, curing agent enables crosslinking, and reductant prevents Cu oxidation. All components work synergistically in one printed layer.
Solution Approach 2:
The solder serves multiple functions: it provides superior electrical coupling, acts as a metallurgical bond during reflow, replaces the sacrificial Cu powder, and forms the final conductive pathway. This multi-functionality reduces the need for separate processing steps.
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 allows for the formation of micro circuit patterns at a lower cost with superior conductivity, using inexpensive Cu and enhancing electrical coupling through the solder, while maintaining uniform thickness and workability.
Implementation Method 1
a solder for electrically coupling the Cu powders
Implementation Method 2
a reductant
Implementation Method 3
a curing agent
Data Source
AI summary
A pattern-forming method for forming a conductive circuit pattern, the pattern-forming method including the steps of: preparing a pattern-forming composition composed of: Cu powder; solder particles for electrically coupling the Cu powder; a polymer resin; a deforming agent that is selected from among acrylate oligomer, polyglycols, glycerides, polypropylene glycol, dimethyl silicon, simethinecone, tributyl phosphare, and polymethylsiloxane, and that increases bonding force between the Cu powder and the solder particles; a curing agent; and a reductant; forming a circuit pattern by printing the pattern-forming composition on a substrate; heating the circuit pattern at a temperature effective to cure the pattern-forming composition and provide the conductive circuit pattern; and electrolytically plating a metal layer onto the conductive circuit pattern. A circuit pattern having superior conductivity is formed at low cost.