The structural composition of the new copper clad laminate and its differences from traditional copper clad laminates.
How the design of this copper clad laminate balances structural reliability and signal loss.
The impact of different material selections on the performance of copper clad laminates.
The preparation methods for copper clad laminates.
Circuit boards made from this copper clad laminate and their applications in electronic devices.
Core Concepts:
Copper Clad Laminate: A substrate material used for manufacturing circuit boards, typically composed of an insulating dielectric layer and a copper foil layer.
Dielectric Loss (Df): The loss of energy of electrical signals in the dielectric material of the circuit board, particularly important at high frequencies.
Conductor Loss: The loss of energy of electrical signals in the circuit board conductor (copper foil), related to the surface roughness of the copper foil.
Elastic Modulus: The ability of a material to resist elastic deformation; the higher the elastic modulus, the harder the material.
Tensile Strength: The maximum stress a material can withstand before breaking under tension.
Dielectric Constant (Dk): The ability of a material to store electrical field energy, affecting signal transmission speed and impedance.
Fluororesin Layer: The main insulating layer in the copper clad laminate, typically having a low Dk and Df.
Copper Clad Structure: Comprising the dielectric layer and copper foil layer, positioned on one or both sides of the fluororesin layer.
Dielectric Layer: The layer located between the fluororesin layer and the copper foil layer, designed to improve bending performance and adhesion of the copper foil.
Copper Foil Layer: The metallic layer used to form electrical circuit traces.
Thermosetting Resin Layer: An optional layer used to improve the bonding performance of the copper clad structure with the fluororesin layer.
Flexible Printed Circuit (FPC): A circuit board that can be bent or folded.
Rigid Printed Circuit Board (PCB): A hard circuit board that cannot be bent.
Key Knowledge Points:
The structure of the copper clad laminate: The core structure of this copper clad laminate includes a fluororesin layer and a copper clad structure positioned on one or both sides. The copper clad structure consists of a dielectric layer and a copper foil layer, with the dielectric layer located between the fluororesin layer and the copper foil layer.
Material property requirements: The elastic modulus of the dielectric layer must be greater than that of the fluororesin layer and less than that of the copper foil layer.
The thickness of the fluororesin layer must be greater than the sum of the thicknesses of the dielectric layers.
The dielectric layer typically has an elastic modulus of no less than 2 GPa and a tensile strength of no less than 200 MPa.
The surface roughness of the copper foil layer must not exceed 1.2 μm.
The fluororesin layer typically has a dielectric constant of less than 3.0 and a loss factor of less than 0.002.
The loss factor of the dielectric layer is usually less than 0.006.
Material selection: The fluororesin layer can be a single-layer structure (such as PTFE, PFA) or a laminated structure (such as PFA/PTFE/PFA).
The dielectric layer can be made of flexible resin (such as MPI, LCP) or rigid resin (such as hydrocarbon resin, polyolefin).
Optional thermosetting resin layer materials may include olefin resins.
Performance advantages: By allowing the dielectric layer to bear part of the bending stress, the bending performance and reliability of the copper clad laminate are improved.
Utilizing the strong adhesion characteristics of the dielectric layer with low roughness copper foil allows for the use of low roughness copper foil, thereby reducing conductor loss.
The fluororesin layer occupies the main thickness and has a lower Dk and Df, thus reducing overall dielectric loss.
Preparation methods: The dielectric layer is coated onto the copper foil layer and cured to form the copper clad structure.
The copper clad structure is positioned on one or both sides of the fluororesin layer.
The copper clad structure is bonded to the fluororesin layer using a hot melt pressing process.
Optionally, a thermosetting resin layer can be coated on the dielectric layer to reduce the bonding temperature.
Applications: Preparation of circuit boards, including flexible printed circuits (FPC) and rigid printed circuit boards (PCB).
The circuit boards can be used in electronic devices (such as mobile phones, tablets, servers, etc.) for electrical interconnection and signal transmission of electronic components.
The resulting circuit boards have lower losses and higher reliability, contributing to improved performance of electronic devices.
In multilayer boards, the design of blind vias can utilize the better chemical corrosion resistance of the dielectric layer compared to the fluororesin layer, ensuring the reliability of electrical connections.
Review Tips:
Refer to the accompanying diagrams to understand the structure of the copper clad laminate and the relationships between the layers.
Focus on key parameters such as the elastic modulus, dielectric constant, and loss factor of each material layer and their impact on the overall performance of the copper clad laminate.
Compare the effects of different material selections on the flexibility/rigidity of the copper clad laminate and the preparation process.
Understand the mechanism by which the dielectric layer improves bending performance and reduces conductor loss.
Review the specific steps of the preparation method, especially the role of the optional thermosetting resin layer.
Consider how this technology addresses the high loss issues of traditional LCP FPCs.
Test Your Understanding:
Short answer questions (2-3 sentences each):
What are the main structural components of the new copper clad laminate?
What is the position and function of the dielectric layer in the copper clad laminate?
What is the relationship between the elastic modulus of the dielectric layer and those of the fluororesin layer and copper foil layer? Why is this relationship adopted?
Why is it better for the surface roughness of the copper foil layer to be smaller? How does the new copper clad laminate solve the problem of weak adhesion between low roughness copper foil and fluororesin?
What is the main role of the fluororesin layer in the new copper clad laminate?
What role does the thermosetting resin layer play in the preparation process?
Besides flexible printed circuits, what other type of circuit board can the new copper clad laminate be used to manufacture?
Why must the thickness of the fluororesin layer be greater than the sum of the thicknesses of the dielectric layers?
In multilayer circuit boards, how can the dielectric layer improve the reliability of electrical connections in blind vias?
How does the choice of material for the dielectric layer (such as MPI, LCP vs. hydrocarbon resin, polyolefin) affect the final application of the copper clad laminate?
Suggested Paper Titles:
Detail how the design principles of the new copper clad laminate balance the low loss requirements of high-frequency signal transmission with the reliability requirements of circuit board structures.
Compare the effects of different dielectric layer materials (such as MPI, LCP, hydrocarbon resin, polyolefin) on the performance of the new copper clad laminate (including electrical performance, mechanical performance, and preparation process).
Explore the potential applications and advantages of the new copper clad laminate in various high-frequency electronic devices (such as 5G communication devices, radar systems, etc.).
Analyze the preparation methods of the new copper clad laminate, focusing on the key technical challenges and solutions in each step.
Research how the design and processing of blind vias in multilayer circuit boards using the new copper clad laminate ensure signal integrity and reliability of electrical connections.
Terminology Compilation:
Copper Clad Laminate (CCL): A substrate material used for manufacturing printed circuit boards, consisting of an insulating layer and copper foil covering it.
Fluororesin Layer: A major insulating material layer in the copper clad laminate, characterized by excellent low dielectric constant and low dielectric loss properties.
Copper Clad Structure: Refers to the structural unit that includes the dielectric layer and copper foil layer, positioned on one or both sides of the fluororesin layer.
Dielectric Layer: The insulating layer located between the fluororesin layer and the copper foil layer, which improves bending performance and adhesion of the copper foil.
Copper Foil Layer: The conductive layer on the copper clad laminate used to form circuit patterns.
Elastic Modulus: The ability of a material to withstand stress within the elastic deformation range, a measure of material stiffness.
Tensile Strength: The maximum stress a material can withstand before breaking under tensile load.
Dielectric Constant (Dk): A measure of a material’s ability to store electrical field energy, affecting the speed of electrical signal propagation in the dielectric.
Loss Factor (Df): A measure of the degree of energy loss in a material under the influence of an electric field, significantly affecting high-frequency signal transmission loss.
Poly Tetra Fluoro Ethylene (PTFE): A common fluororesin with very low Dk and Df, high temperature resistance, and chemical resistance.
Poly Fluoro Alkoxy (PFA): Another fluororesin with properties similar to PTFE but with better melt processability.
Polyimide (PI): A high-performance polymer with good high-temperature resistance and mechanical properties, used as a substrate for flexible printed circuits.
Modified Polyimide (MPI): A modified version of PI to improve certain properties, such as dielectric performance or bending performance.
Liquid Crystal Polymer (LCP): A polymer material with excellent electrical performance, mechanical performance, and heat resistance, commonly used in high-frequency flexible printed circuits.
Hydrocarbon Resin: A type of resin primarily composed of carbon and hydrogen, used as a substrate for rigid circuit boards, typically with lower Dk and Df.
Polyolefin: A class of polymers formed by the polymerization of olefin monomers, such as polyethylene and polypropylene, some of which can be used as substrates for rigid circuit boards with lower Dk and Df.
Thermosetting Resin Layer: A type of resin layer that undergoes a chemical reaction and solidifies upon heating, used to improve bonding between layers or reduce bonding temperature.
Olefin Resin: Refers to resins formed by the polymerization of olefin monomers, commonly used as materials for thermosetting resin layers.
Hot Melt Pressing Process: A process that uses heat and pressure to bond material layers together.
Circuit Board: A board used to support electronic components and provide electrical connections.
Flexible Printed Circuit (FPC): A printed circuit board that can be bent or folded.
Printed Circuit Board (PCB): Typically refers to rigid printed circuit boards.
Conductive Line: The conductive path formed on the circuit board to connect electronic components.
Blind Via: A conductive hole that connects inner layers and the surface layer but does not penetrate the entire thickness of the circuit board.
Short answer question answers:
The new copper clad laminate mainly includes a fluororesin layer and a copper clad structure positioned on one or both sides, where the copper clad structure contains a dielectric layer and a copper foil layer.
The dielectric layer is located between the fluororesin layer and the copper foil layer, and its function is to bear part of the bending stress when the copper clad laminate bends and to improve adhesion with low roughness copper foil.
The elastic modulus of the dielectric layer is greater than that of the fluororesin layer and less than that of the copper foil layer. This relationship allows the dielectric layer to distribute stress during bending, protecting the fragile copper foil layer.
The smaller the surface roughness of the copper foil layer, the lower the conductor loss. The new copper clad laminate addresses the weak adhesion issue between low roughness copper foil and fluororesin by introducing a dielectric layer with strong adhesion characteristics to low roughness copper foil.
The fluororesin layer serves as the main insulating layer, with extremely low dielectric constant and loss factor, effectively reducing the dielectric loss of the copper clad laminate.
The thermosetting resin layer is optional; it can be coated on the dielectric layer, reducing the difficulty of the manufacturing process by allowing bonding at medium temperatures.
Besides flexible printed circuits (FPC), when the dielectric layer is made of rigid resin, the new copper clad laminate can also be used to manufacture rigid printed circuit boards (PCB).
The thickness of the fluororesin layer must be greater than the sum of the thicknesses of the dielectric layers to ensure that even if the dielectric layer has slightly higher losses, the overall dielectric loss remains low, as the fluororesin layer is the main dielectric of the copper clad laminate.
In multilayer boards, the dielectric layer corresponding to the bottom of the blind vias can be more easily corroded away by chemical agents compared to the fluororesin layer, avoiding issues with incomplete adhesive removal due to the strong chemical resistance of the fluororesin, thus ensuring the reliability of electrical connections.
The choice of material for the dielectric layer determines whether the copper clad laminate is flexible or rigid. Flexible resins (MPI, LCP) are used to make FPCs, while rigid resins (hydrocarbon resin, polyolefin) are used to make PCBs.
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