8 Layer Multilayer HDI PCB Cost With Blind Vias printed circuit boards Prototype

General information:

Layer:8

Material:FR4

Thickness: 2.0MM

Surface finish: ENIG

Special: Blind hole,L1-L2,L3-L4,L5-L6,vias filled and capped

Board size:2*6CM

Solder mask:No

Silk screen: White

Name: Multilayer 8Layer Blind Vias PCB Boards

Delivery time: 10days for sample and small&medium batch

About quote:For the special of blind vias pcb,so the accurate quotation have to provide the gerber file(DXP etc.)

Package Details: inner packing:vacuum packing/plastic bag outer packing:standard carton packing

Blind vias:

Blind vias are used to connect one outer layer with at least one inner layer.

The holes for each connection level must be defined as a separate drill file.

The ratio of hole depth to drill diameter (aspect ratio) must be ≤ 1.

The smallest hole determines the depth and thus the max. distance between the

outer layer and the corresponding inner layers.

For detail blind&buried vias pcb

Key words: Microvia, Via-in-Pad

HDI Blind vias PCB:

HDI boards, one of the fastest growing technologies in PCBs, HDI Boards contain blind and/or buried vias and often contain microvias of .006 or less in diameter. They have a higher circuitry density than traditional circuit boards.

There are 6 different types of HDI boards, through vias from surface to surface, with buried vias and through vias, two or more HDI layer with through vias, passive substrate with no electrical connection, coreless construction using layer pairs and alternate constructions of coreless constructions using layer pairs.

Special technologies used with HDI any-layer printed circuit boards:

Edge plating for shielding and ground connection

Minimum track width and spacing in mass production around 40μm

Stacked microvias (plated copper or filled with conductive paste)

Cavities, countersunk holes or depth milling

Solder resist in black, blue, green, etc.

Low-halogen material in standard and high Tg range

Low-DK Material for Mobile Devices

All recognised printed circuit board industry surfaces available

How can I ensure proper stitching vias or ground vias in my HDI PCB design?

1,Determine Via Spacing and Distribution: Determine the spacing and distribution of stitching vias or ground vias based on the specific requirements of your design. The spacing between vias depends on the frequency of the signals and the desired level of isolation. Closer spacing provides better isolation but increases manufacturing complexity and cost.

2,Place Vias Along Signal Traces: To ensure effective coupling between the signal layers and the ground plane, place stitching vias or ground vias regularly along the signal traces. The vias should be distributed evenly and follow a consistent pattern. Consider placing vias at regular intervals, such as every few centimeters, or at critical points where signal transitions occur.

3,Connect Vias to Solid Ground Plane: Stitching vias or ground vias should be connected to a solid ground plane to provide an effective return path for the signals. Ensure that the vias directly connect to the ground plane without any interruptions or gaps.

4,Use Sufficient Via Diameter and Aspect Ratio: Select an appropriate via diameter and aspect ratio to ensure sufficient conductivity and thermal dissipation. Larger via diameters provide lower impedance and better conductivity. Consider the manufacturing capabilities of your PCB manufacturer when determining the via size, as smaller vias may require more advanced fabrication techniques.

5,Avoid Via Stub Lengths: Minimize the length of via stubs, which are the portions of the via that extend beyond the signal layer. Via stubs can create impedance discontinuities and increase signal reflections. Use blind or buried vias when possible to minimize via stub lengths.

6,Consider Ground Via Arrays: Instead of single vias, you can use ground via arrays or via fences. These consist of multiple vias arranged in a grid or a specific pattern to enhance the coupling between signal layers and the ground plane. Ground via arrays provide better isolation and reduce the inductance of the return path.

7,Perform Signal Integrity Analysis: Conduct signal integrity analysis, including simulation and modeling, to evaluate the effectiveness of stitching vias or ground vias. Simulations can help identify potential issues such as impedance variations, crosstalk, or resonance effects. Adjust the via distribution or geometry as needed based on the analysis results.

How can I determine the characteristic impedance of transmission lines in my HDI PCB design?

1,Empirical Formulas: Empirical formulas provide approximate calculations of characteristic impedance based on simplified assumptions. The most commonly used formula is the microstrip transmission line formula, which is suitable for traces on an outer layer of the PCB. The formula is: Zc = (87 / √εr) * log(5.98h / W + 1.74b / W) Where:

Zc = Characteristic impedance

εr = Relative permittivity (dielectric constant) of the PCB material

h = Height of the dielectric material (trace thickness)

W = Width of the trace

b = Separation between the trace and the reference plane (ground plane) It is important to note that empirical formulas provide approximate results and may not account for all the complexities of the PCB structure.

2,Field Solver Simulations: To obtain more accurate results, electromagnetic field solver simulations can be performed using specialized software tools. These tools consider the specific layer stackup, trace geometry, dielectric materials, and other factors to accurately calculate the characteristic impedance. Field solver simulations take into account the effects of fringing fields, dielectric losses, and other factors that influence the impedance. Field solver software tools, such as Ansys HFSS, CST Studio Suite, or Sonnet, allow you to input the PCB structure, material properties, and trace dimensions to simulate the transmission line and obtain the characteristic impedance. These simulations provide more precise results and are recommended for high-frequency applications or when accurate impedance control is crucial.

What are some challenges in implementing HDI PCB technology in automotive electronics?

Implementing HDI PCB technology in automotive electronics does come with its set of challenges. Some of the key challenges include:

Reliability and Durability: Automotive electronics are subjected to harsh environmental conditions, including temperature variations, vibrations, and moisture. Ensuring the reliability and durability of HDI PCBs in such conditions becomes crucial. The materials used, including the substrates, laminates, and surface finishes, must be carefully selected to withstand these conditions and provide long-term reliability.

Signal Integrity: Automotive electronics often involve high-speed data transmission and sensitive analog signals. Maintaining signal integrity becomes challenging in HDI PCBs due to the increased density and miniaturization. Issues such as crosstalk, impedance matching, and signal degradation need to be carefully managed through proper design techniques, controlled impedance routing, and signal integrity analysis.

Thermal Management: Automotive electronics generate heat, and effective thermal management is essential for their reliable operation. HDI PCBs, with their higher circuit density, can have increased power densities, making heat dissipation more challenging. Proper thermal design considerations, including heat sinks, thermal vias, and effective cooling mechanisms, are necessary to prevent overheating and ensure the longevity of components.

Manufacturing Complexity: HDI PCBs involve more complex manufacturing processes compared to traditional PCBs. The sequential build-up process, laser drilling, and fine-pitch component assembly require specialized equipment and expertise. The challenges arise in maintaining tight manufacturing tolerances, ensuring accurate alignment of microvias, and achieving high yields during production.

Cost: The implementation of HDI PCB technology in automotive electronics can increase the overall manufacturing cost. The use of advanced materials, specialized manufacturing processes, and additional quality control measures can contribute to higher production expenses. Balancing the cost factor while meeting the performance and reliability requirements becomes a challenge for automotive OEMs.

Regulatory Compliance: Automotive electronics are subject to strict regulatory standards and certifications to ensure safety and reliability. Implementing HDI PCB technology while meeting these compliance requirements can be challenging, as it may involve additional testing, validation, and documentation processes.

Addressing these challenges requires collaboration between PCB designers, manufacturers, and automotive OEMs to develop robust design guidelines, select suitable materials, optimize manufacturing processes, and conduct thorough testing and validation. Overcoming these challenges is essential to leverage the benefits of HDI PCB technology in automotive electronics and deliver reliable and high-performance electronic systems in vehicles.