dielectric metarial: FR-4

 Sheet thickness: 0.7 mm

Copper thickness: 1 / 1 oz

Minimum line width: 0.3 mm / 0.22mm

Surface finished： lead-free

Board Material Parameters:

Dielectric Constant (Dk): It is a characteristic coefficient that measures the insulating ability and directly affects the signal transmission rate. Generally, the smaller the Dk value, the faster the signal propagation speed; conversely, the slower. For ultra-long PCBs, it is necessary to select board materials with stable and relatively low Dk values.

Dissipation Factor (Df): It reflects the loss of signals during transmission. The smaller the Df value, the less signal loss and the higher the signal quality. For ultra-long PCBs with high-speed signal transmission, board materials with low Df values should be chosen.

Moisture Absorption: It indicates the degree to which the PCB board material absorbs water under normal atmospheric pressure. High moisture absorption can increase the dielectric constant and dissipation factor, so board materials with low moisture absorption rates should be selected.

Coefficient of Thermal Expansion (CTE): It measures the change in length of a material with temperature changes. Selecting board materials with a smaller CTE can ensure dimensional stability of the PCB during temperature variations.

Electrical Performance Parameters:

Impedance Control: Impedance control is particularly important for ultra-long PCBs. Impedance is related to parameters such as dielectric constant, copper thickness, and line width, and needs to be precisely controlled to ensure the quality of signal transmission.

Surface Resistivity and Volume Resistivity: They respectively represent the resistance to current flow on the surface layer and within the insulating material. These two parameters are crucial for ensuring the electrical performance and safety of the PCB.

Mechanical Performance Parameters:

Flexural Strength: It refers to the ability of a material to resist bending without breaking. For ultra-long PCBs, board materials with high flexural strength should be chosen to ensure stability during processing and use.

Peel Strength: It refers to the maximum force required to peel apart materials that are bonded together per unit width of the contact surface. For ultra-long PCBs, the peel strength between the copper foil and the substrate needs to meet certain requirements to ensure reliable connections.