HDI PCBs are Gaining Popularity, Know Why

High Density Interconnect (HDI) are integral elements of advanced electronics. They are referred by a variety of names, such as Microvia Process (MVP), Sequence Build Up (SBU), and Build Up Multilayer Boards (BUM). These PCBs are loaded with technical characteristics, which make them ideal for today’s devices demanding excellent performance, and lightweight designs. This post attempts to answer all questions that you may have regarding HDI PCBs.

What are HDI PCBs?

High Density Interconnect (HDI) PCBs receive their name from high density routing connections, which hold a large number of components. These high density routing connections have helped reduce the footprint of various popular electronic devices such as tablets, smartphones, computers, and wearable technology products like Virtual Reality (VR devices), and fitness bands.

Why to Use HDI PCBs?

HDI PCBs offer several technical advantages over Surface Mounted (SMT) and through-hole boards.

• Design Flexibility: The HDI board offers more design flexibility to a designer than SMT or through-hold board. The designer can take advantage of high component density, which aids in faster signal processing.
• Small Footprint: Due to advanced technical characteristics, HDI boards can easily accommodate more connections in the same board with a less number of layers.
• Reliability: The HDI boards have small vias, which offer superior reliability over through hole vias due to its low Aspect Ratio (AR).
• Ideal for Dense and Complex Packages: HDI is an option for dense and complex packages, where high pin counts, as well as low pitches are involved.
• Increasing Demand for Small Printed Circuit Boards: HDI boards fulfill the increasing demand for small PCBs. Non-HDI boards claim more space and weight, which makes them difficult to use in many situations. Also, multiple PCBs can be integrated into a single HDI.
• Signal Integrity: Advanced technical characteristics of this PCB helps improve signal integrity, and electrical performance, which makes them simply popular over SMT or through-hole boards.

What are the Things to Keep in Mind While Designing a HDI PCB?

As with any other PCB technology, HDI PCB demands some specific concerns such as:

• Material: Although all PCB manufacturing takes material into account, HDI PCB takes them seriously, due to several manufacturing constraints imposed. The electrical performance of signal traces will depend on the type of material selected. The choice of material is also a leading factor in cost decision.
• Every Layer Interconnection (ELIC): This technique is now employed in the construction of smartphones. It helps reduce mechanical holes, and creates smaller pitches inside the circuit board.
• Track Uniformity and Minimum Line Width: These are the important considerations to make to avoid short circuit or open connections.
• Component Layout: The HDI technology emphasizes on accurate component placement. This placement helps ensure viability in installation, soldering, and maintaining boards.
• Distribution of Buried and Blind Holes: Asymmetric stack designs may generate unnecessary pressure, thereby causing warpage of boards.
• Skill Sets: The layer counts, high density component placements, and manufacturing complexity are some of the factors that need to be considered before sending your PCB to a fabricator. Any sort of design problems encountered during the manufacturing may be costly, and may require complete redesign or scrapping.

Design complexity, demand for accuracy, and increasing relevance of compact sized PCBs are some of the factors, which have shifted spotlight on HDI PCB planning, layout and manufacturing. These reasons are also forcing PCB designers and OEMs to outsource their manufacturing to experts. Sierra Assembly Technology, Inc. is a leading manufacturer of HDI PCBs in the US. The PCBs are used in various industrial applications.