Resin Composite Copper Foil Adhesion and Heat Resistance
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Solution Overview
Problem
Conventional resin composite copper foils face challenges in achieving adequate adhesion strength and heat resistance, especially when used in high-density printed wiring boards with fine circuits, due to surface unevenness and moisture absorption, which affects the reliability of lead-free soldering processes.
Innovation Solution
A resin composite electrolytic copper foil with a roughened surface and a layer of block copolymerized polyimide resin containing an inorganic filler and maleimide compound, applied to provide improved adhesion and heat resistance by enhancing the synergistic effect between the copper foil surface and resin composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional electrolytic copper foil with uneven surface is used, then adhesion strength to resin is improved, but circuit formation precision deteriorates due to convex portions remaining on insulating surface
Solution Approach 1:
The invention applies a resin composition layer specifically on the copper foil surface to create a flat insulating surface. This local modification allows the copper foil to maintain its inherent adhesion properties while the resin layer provides the necessary flatness for precise circuit formation, resolving the contradiction between adhesion strength and circuit precision.
Solution Approach 2:
The invention creates a composite structure by forming a resin composition layer on the copper foil surface. This composite material combines the adhesion advantages of the uneven copper surface with the flatness of the resin layer, simultaneously achieving both strong adhesion and precise circuit formation.
2Manufacturing precision
If low profile copper foil with suppressed unevenness is used, then circuit formation precision is improved, but adhesion strength to highly heat resistant thermosetting resin deteriorates
Solution Approach 1:
The resin composition layer is applied locally on the copper foil surface to provide flatness where needed for circuit formation, while the underlying copper foil structure maintains its adhesion properties. This localized approach allows simultaneous achievement of both precision and adhesion.
Solution Approach 2:
The composite structure of copper foil with resin composition layer combines the flatness of the resin surface with the adhesion properties of the copper, resolving the contradiction between circuit precision and adhesion strength to thermosetting resin.
3Strength
If resin composite copper foil with adhesive layer is used, then adhesion strength is improved, but heat resistance deteriorates under moisture absorption
Solution Approach 1:
The invention specifies precise compositional parameters for the resin composition layer, including the use of polyimide resin with specific glass transition temperature ranges and controlled moisture absorption properties. By controlling these parameters, the resin layer provides both adhesion and heat resistance under moisture conditions.
Solution Approach 2:
The composite structure uses a resin composition layer with specifically selected materials (polyimide resin, inorganic filler, coupling agent) that provide both adhesion strength and heat resistance. The composite nature allows the resin to bond to copper while maintaining thermal stability and moisture resistance.
4Ease of manufacture
If conventional copper foil is used for lead-free soldering, then manufacturing cost is reduced, but reliability deteriorates due to insufficient heat resistance
Solution Approach 1:
The resin composition layer is designed with specific thermal properties including glass transition temperature between 180-250°C and controlled moisture absorption (0.03-0.15%). These parameter specifications enable the material to withstand lead-free soldering temperatures while maintaining adhesion and dimensional stability, providing both cost-effectiveness and reliability.
Solution Approach 2:
The composite structure combines copper foil with a resin composition layer containing polyimide resin, inorganic filler, and coupling agent. This composite provides the necessary heat resistance for lead-free soldering while maintaining manufacturing feasibility and cost-effectiveness.
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 results in a copper clad laminate with excellent adhesion strength and heat resistance, suitable for high-density printed wiring boards, particularly after desmear treatment, and improved performance under lead-free soldering conditions.
Implementation Method 1
a resin composition layer (B) containing a block copolymerized polyimide resin (a) and 2,2-bis[4-(4-maleimidephenoxy)phenyl]propane (b) formed on one surface of the electrolytic copper foil (A)
Implementation Method 2
a roughened surface having a plurality of minute projections, a surface roughness (Rz) within a range of 1.0 μm to 3.0 μm and a lightness value of not more than 30 on one surface of an electrolytic copper foil (A)
Implementation Method 3
2,2-bis[4-(4-maleimidephenoxy)phenyl]propane (b)
Data Source
AI summary
The problem of the invention is to provide a resin composite electrolytic copper foil having further improved heat resistance and improved plate adhesion strength when plated after desmear treatment in the work process of an additive method. The solution is to form a roughened surface having a plurality of minute projections, a surface roughness (Rz) within a range of 1.0 pm to 3.0 pm and a lightness value of not more than 30 on one surface of an electrolytic copper foil (A), and form a layer of a resin composition (B) containing a block copolymerized polyimide resin (a) having a structure that imide oligomers of a first structural unit and a second structural unit are bonded alternately and repeatedly on the roughened surface.