PCB HDI Facilitate
High-speed electronic signals require short internal wire lengths to meet signal integrity requirements. High-pin-count BGA packages are a common solution to this requirement, but the dense package layout presents challenging routing issues. BGAs typically have a large number of pins (1,500 and up) with a large surface area, which requires extra board layers to accommodate the connections. Fortunately, PCB HDI facilitates BGA routing by reducing the number of layers required for high-pin-count applications.
A typical pcb hdi board is built using a sequential lamination process. The core is constructed and laminated first, followed by a stack-up layer with components and traces. The HDI layer stack is then added over the core, allowing for replacement of conventional vias with microvias that can reduce board layer count. The result is a more efficient circuit that meets your reliability and performance goals.
The advantage of using microvias over through-holes is the lower parasitic inductance and capacitance, which allow for smaller traces and shorter internal wire lengths. In addition, the thinner dielectrics used in microvias improve heat dissipation, which is a significant concern on high-speed circuits. This helps to ensure signal integrity and reduced noise from current-carrying paths.
How Does PCB HDI Facilitate High-Pin-Count BGA Routing?
Another benefit of using microvias is the flexibility they offer to route signals. These small holes can be positioned in, offset from, or tangent to the surface mount pads, which increases routing density. They also enable via-in-pad designs and provide more space for power/ground copper, which is important for power integrity (PI) and EMC. The small gaps caused by the microvias also have a minimal impact on signal transmission and impedance.
In addition to the increased routing density, HDI offers a number of other advantages. It allows for a higher component density and faster turnarounds. In addition, it can help to reduce manufacturing costs through more efficient use of materials and a reduction in the number of layers needed for signal routing. It can also reduce manual routing time for even the most complex projects.
Ultimately, the most valuable aspect of using HDI is its ability to increase reliability. The increased routing density of HDI boards can significantly reduce the size and complexity of the PCB, which decreases the risk of failure and enhances the life cycle of the product. In addition, the increased flexibility of HDI boards can make it easier to adapt to future product upgrades and redesigns.
To achieve optimal results, designers should consult recommended routing patterns and take into account the fabricator’s limitations when designing a board. This will help to ensure that the final board design is compatible with the manufacturing process and meets your requirements for quality, cost, and lead time.
In addition, designers should consider how the component placements will affect the metallization and coating options for the final board. For example, thicker traces and vias can reduce the thickness of the final board and limit the availability of the soldering process. In addition, a thinner board can reduce the total amount of copper used.