What are the special processes for PCB manufacturing ?
2024-08-16
1. Gold Finger
Gold finger is a gold-plated pillar on the edge of the PCB connection, which is mainly used to assist the connection of the PCB with the computer motherboard or other equipment. The gold finger is gold-plated, which enhances the conductivity and abrasion resistance, ensuring the stability and reliability of signal transmission. Common gold plating processes include electroless nickel immersion (ENIG) and electroplating hard gold, the latter of which is particularly suitable for frequent mating and unplugging due to its high adhesion and hardness.
2. Impedance control
Impedance control is a critical process in PCB design to ensure signal integrity. The characteristic impedance values of the PCB must match the electronic impedance of the head and tail components to avoid signal reflection, scattering, attenuation, or delays. By accurately designing PCB impedance strips and impedance lines, and controlling parameters such as wire resistance, inductance, and capacitance, the signal is transmitted as intended. This process is especially important for high-speed circuits.
3. Blind & Buried Vias
Blind and buried vias are special via structures commonly found in high-density interconnect (HDI) PCBs. Blind vias are holes that are drilled from the top or bottom layer of the PCB but do not penetrate the entire board, while buried vias are located entirely in the inner layers of the PCB. The application of these holes reduces the number of layers and size of the PCB, improves electromagnetic compatibility, reduces costs, and simplifies design efforts.
4. Heavy Copper PCB
Thick copper PCBs refer to circuit boards that use thicker copper foil than standard PCBs in the manufacturing process. The thickness of standard copper foil is generally around 35 microns, while the copper thickness of thick copper plates can reach 105 microns or even higher. With high current carrying capacity, good thermal management performance and enhanced mechanical strength, thick copper plates are suitable for high-power, high-current and harsh environment applications, such as automotive electronics and industrial control systems.
5. Multi-layer special laminated structure
The multi-layer special stacked structure realizes the effective isolation of signals and the suppression of electromagnetic interference by reasonably arranging the signal layer, power layer and ground layer. For designs with a large number of signals, large device density, and high signal frequency, the use of multi-layer special stack structure can significantly improve the EMC performance of the PCB, ensure the integrity of the signal and the stability of the system.
6. Non-Circular Holes
Special-shaped holes refer to non-circular holes encountered in PCB fabrication, such as figure-8 holes, diamond-shaped holes, square holes and zigzag holes. These holes are available in two types: Copper in the Hole (PTH) and Copper in the Hole (NPTH) depending on the design requirements. With the development of diversification of electronic products, special-shaped holes are widely used in the fixing and interconnection of special components, which improves the flexibility and adaptability of PCB.
7. Controlled Depth Slots
Depth control groove is to process a groove of a specific depth on the PCB to meet the installation and fixing needs of special components. This process is often used to secure heat sinks, connectors, or other components that require precise depth control, improving the accuracy and reliability of PCB assembly.
8. Half Hole & Edge Wrap
The half-hole process is the formation of a partially penetrated hole at the edge of the PCB, while edging refers to the addition of an additional layer of copper foil to the edge of the hole to enhance the strength of the connection. These processes are commonly used in the design of edge connectors and special interfaces to improve the reliability and durability of the connection.
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