Current Trends in PCB HDI Technology
The proliferation of smart products and the Internet of Things (IoT) has increased the demand for high-density circuit boards that can accommodate a larger number of components in smaller spaces. The use of HDI PCBs allows engineers to route more connections and power within densely packed board layouts without compromising performance. The technology also offers greater design flexibility by allowing engineers to use fine line traces to intricately connect devices.
This advanced technology is being used in everything from cell phones to automobiles. In fact, modern vehicles are becoming more sophisticated with onboard computers that control engine diagnostics and safety features, among other functions. Increasingly, these devices require high-speed signals to transmit information quickly and reliably. HDI circuit boards can help manufacturers achieve these requirements with greater interconnection density, smaller size and reduced weight.
The pcb hdi manufacturing process uses two essential techniques, microvia drilling and sequential lamination. Microvia drilling creates small, high-density interconnections by making holes in the core material to establish connections between different layers. The sequential lamination process then bonds thin sheets of insulating and conductive materials to the core.
What Are the Current Trends in PCB HDI Technology?
Microvia drills can only penetrate the core to a certain depth, so they have a lower aspect ratio limit than conventional through-hole vias. A typical aspect ratio for a through-hole via in an HDI PCB is less than 1. For buried vias, a manufacturer may offer reliability claims up to a maximum of 2. In most cases, a designer will select via styles that meet these constraints, although the choice will depend on the specific application and its signal transmission requirements.
Another trend in the PCB industry is to move away from using copper-filled plated vias for interconnects, which are traditionally used to increase circuit board density and allow for lower layers and thinner finished boards. Instead, designers can choose to use via-in-pad (ViP) processes that are typically used in high-speed applications and have better signal transmission properties. ViPs can also be designed to support BGA packages with smaller ball pitch and a higher I/O count, as well as provide routing density for complex designs.
While the advantages of HDI circuit boards are clear, designing a board with this technology requires significant engineering effort. This is especially true in the early stages of the design process, as there are more restrictions placed on the designer. For example, the traces must be kept to a minimum width, the metallization must be carefully managed, and the manufacturing process must be able to produce these structures with tight tolerances. In addition, the board must be fabricated in a cleanroom environment. These challenges are driving many engineers to work with HDI-certified board fabricators that can offer a seamless transition from traditional PCBs to the latest technologies.
