What processes can improve the speed of PCB circuit boards

　　Improving the signal transmission speed of PCB circuit boards is a systematic engineering that involves multiple levels from design, materials to manufacturing processes. The following are key directions that can be improved from a manufacturing and process perspective:

　　1、 Core material and process improvement

　　Using low dielectric constant (Low Dk) and low loss factor (Low Df) substrates

　　Process key: High frequency specialized boards (such as Rogers series, Panasonic's MEGTRON series, Isola's FR408HR, etc.) are used, which have low dielectric loss and signal distortion under high-speed signals.

　　Effect: Directly reducing signal propagation delay and attenuation is the foundation for improving speed.

　　Using a thinner dielectric layer

　　Process key: Strictly control the multi-layer board pressing process to achieve thinner and more uniform dielectric layers (such as Prepreg).

　　Effect: Reduce the distance between the signal layer and the reference plane (ground/power layer), enhance coupling, reduce transmission line inductance, and improve signal integrity.

　　2、 Improvement of transmission line manufacturing process

　　Fine lines and spacing control

　　Process key: Advanced laser direct imaging (LDI) and fine line etching processes are used to achieve smaller line widths/distances (such as 3/3 mil, or even smaller).

　　Effect: Allow for more and better transmission lines to be arranged in a limited space, supporting higher wiring density and impedance accuracy.

　　Strict impedance control

　　Process key: By precise lamination thickness control, etching factor compensation, and real-time process monitoring, ensure that the tolerance of transmission line impedance (such as 50 Ω, 90 Ω differential) reaches ± 5% or lower.

　　Effect: Minimize signal reflection and ensure signal quality.

　　3、 Enhancement of Stacking and Interconnection Processes

　　Optimize stacked design and blind buried hole technology

　　Process key: Adopting high thickness to diameter ratio drilling, laser drilling blind/buried holes (HDI process), hole filling electroplating and other technologies.

　　effect

　　Shorten the signal path and reduce signal reflection and attenuation caused by through hole stub.

　　Realize a more compact layout, reduce signal transmission distance and inter layer switching.

　　Surface treatment optimization

　　Process key: For high-speed signals, choose low loss and high surface flatness processing techniques, such as chemical nickel palladium (ENEPIG) or immersion silver.

　　Effect: Reduce signal loss and impedance discontinuity on the pad surface, superior to traditional HASL (hot air leveling).

　　4、 Power integrity support process

　　Low inductance power distribution network (PDN)

　　Process key:

　　Use thin dielectric cores (such as ≤ 0.1mm) to achieve tighter power/ground plane coupling.

　　Use multiple pairs of decoupling capacitors in parallel, small-sized capacitors (such as 0201/01005), and place them as close as possible to the chip pins.

　　Optimize the design of via array to reduce the impedance of planar connections.

　　Effect: Provide stable and low-noise power supply for high-speed chips, preventing signal timing jitter caused by power supply noise.

　　Back drilling technology

　　Process key: In the through-hole plate, perform secondary drilling to remove the through-hole parts that are not used for connecting deep signals.

　　Effect: Eliminate excess through-hole residues and significantly reduce signal integrity issues when high-speed signals (especially>1GHz) pass through long through holes.

　　5、 Collaborative Design and Simulation

　　Design Manufacturing Integration (DFM for SI/PI)

　　Process key: Manufacturers intervene early and provide design rules and models based on their actual process capabilities, such as etching profiles, medium thickness tolerances, and material Dk/Df fluctuations.

　　Effect: Ensure high consistency between design simulation and physical performance, avoiding speed bottlenecks caused by "design feasibility, manufacturing deviation".

　　Improving PCB speed is not a breakthrough in a single process, but requires a systematic effort in material selection, stack design, manufacturing accuracy and control, as well as close collaboration with the design team. For specific projects, in-depth communication should be conducted with PCB suppliers with experience in high-speed board manufacturing, and appropriate process combination plans should be developed based on factors such as signal speed and cost budget.