As the size of electronic devices
shrinks and functionality expands, there has never been a greater demand for
compact, high-performance circuit boards for the ever-growing needs. Here
enters the HDI PCB: a High-Density Interconnect PCB, technology enables
designers to pack the more functional power into a smaller space.
Advanced design techniques like micro
vias, blind vias, buried vias, and fine trace widths for higher wiring density
and superior signal integrity make HDI boards great candidates for applications
in such areas as smartphones, tablets, wearables, automotive, and medical
electronics.
What is an HDI PCB?
HDI PCB or High-Density Interconnect Printed Circuit Boards are
modern circuit boards that offer comparatively more wiring density per unit
area than standard PCBs. Designers can build smaller, higher-performance
electronics using fine lines and spaces, smaller vias, and higher connection
pad density.
With HDI technology, an advanced way of organizing space, it becomes
possible to place more active components into a small space. This is
accomplished by microvias, blind and buried vias, and multiple layers laminated
in sequence. These characteristics make HDIs well-suited for the modern
applications of smartphones, tablets, wearables, medical devices, and compact
electronics.
As demand for electronic products grew, so did the importance of HDI
PCBs in electronics manufacturing. The flexibility in design and advantages of
performance have made them the best choice for engineers and HDI PCB
manufacturers across the globe.
HDI PCB Stack-Up
HDI PCB Stack-up is a specific arrangement
of conductive and insulating layers within an HDI board. Unlike the
conventional PCB, HDI boards feature combinations of microvias, blind vias, and
buried vias to make layer connections, so that routing may have complexity, and
component density may increase.
The typical HDI stack-up contains one or
more sequences of laminations, thus providing additional routing without
increasing the size of the board. Some of the popular configurations include:
• 1+N+1: One microvia layer
on each side of a core
• 2+N+2: Two microvia layers
on each side providing routing channels
• Any Layer HDI: Microvias
can connect to any layer, thus providing maximum design flexibility.
The choice of HDI PCB stack-ups directly
relates to the signal integrity, thermal performance, and manufacturability of
a device. A well thought stack-up minimizes signal loss while minimizing
crosstalk, which supports high-speed data transmission.
Key HDI Benefits
The HDI PCBs have many advantages,
thus becoming the favorable choice for modern electronic design. HDI PCB
technology, which offers increased density of components and better electrical
performance, can be used to build faster, smaller, and much more reliable
devices.
Here are some of the key benefits of
using HDI boards:
• Miniaturization:
Thanks to the
finer traces and microvias, the HDI PCBs support the most compact of layouts
and make them ideal for space-constraint applications such as smartphones and
wearables.
• Improved Electrical Performance:
Reduced delays
and improved signal integrity are the benefits gained from shorter signal paths
and reduced parasitic effects and, therefore, higher frequency performance.
• Higher Layer Density:
More layers can
be accommodated within HDI stack-ups without increasing the thickness of a
board, thus maximizing functionality on a limited surface.
• Flexibility:
Blind and buried
vias make HDI PCB designers freer to play with their layouts.
• Improved Management of Heat:
New via
structures improve thermal dissipation, making the board more reliable.
• More Reliable:
Laser-drilled
microvias are stronger and less prone to failure than microvias
mechanically drilled in conventional PCBs.
What’s Different about HDI PCB Design and Manufacturing?
The designing and manufacturing of HDI
PCBs is highly complicated processes, unlike standard PCB design and
manufacture. Because of their compact sizes and sophisticated configuration,
HDI design requires extreme attention to detail, tight tolerances, and control
over every step of manufacturing.
HDI PCB Design Differences:
Unlike traditional boards, HDI PCB design revolves around high density but without compromising
performance. Designers use:
• Microvias and
blind/buried vias for reduced layer-to-layer distance.
• Via-in-pad
technology saves space and gives users the ability to position fine-pitch BGA components.
• High-speed signal routing techniques that
keep signals in that high-density layout intact.
Manufacturing Process Differences:
The HDI PCB manufacturing process includes:
• Laser drilling
for microvias offers precision that is not achievable with mechanical drills.
• Sequential
lamination to build up multilayer stacks one step at a time.
• Advanced inspection and testing to detect
minute defects due to the fine features.
HDI PCB Design Guidelines
For an HDI board to perform optimally, one
must have a good grip on all layout constraints, materials chosen, and
manufacturing capabilities. Since an HDI design is aimed for achieving max
density and performance in a compact area, proper guideline indeed assures
functionality with manufacturability.
Key HDI Design
Considerations:
Microvia Usage
Microvias are a key element of HDI
boards. Use them strategically to connect adjacent layers and enable dense
component placement without compromising signal paths.
Via-in-Pad Technique
Via-in-pad is one way to make a
compact design with good routing efficiency, but it also entails filling and
plating the via during manufacturing. This is especially useful for BGAs.
Controlled Impedance Routing
Most HDIs carry high-speed signals;
thus, maintaining controlled impedance becomes a must. Pay attention to trace
width, spacing, and stack-up configuration to avoid signal degradation.
Proper Stack-Up Planning
Involve your HDI PCB manufacturer early in
the design phase so that a feasible HDI PCB stack-up can be agreed upon. This
will have impacts on impedance, layer count, thermal performance, and costs.
Design for Manufacturability (DFM)
Keep
your design within the tolerance limits of your chosen HDI PCB manufacturer.
Use standard drill sizes and ensure that your design rules are in sync with
those of the fabricator to avoid production delays.
Thermal Management
The denser the layout, the more heat is
generated. Use thermal vias together with even copper distribution for
temperature control and reliability.
HDI PCB Manufacturing Process
The HDI PCB-manufacturing process is
heavily complex compared to the standard PCBs due to its finer features and
multi-layered nature. Intricate steps of making HDI boards ensure
reliability and performance with high-precision equipment and strict process
control.
Material Preparation
HDI PCBs are made from
high-performance base materials like FR4 or advanced laminates with properties
supporting fine-line resolution and thermal stability.
Laser Drilling
Microvias connecting adjacent layers
are formed with laser drilling. Unlike traditional mechanical drilling, laser
technology is capable of producing the utmost accuracy required in the fine
geometries of HDI PCB technology.
Electroless and Electroplating
In this step, the microvias are
copper-plated to establish conduction paths after the drilling has taken place.
This is vital since it provides electrical connectivity and long-term
reliability.
Sequential Lamination
Layers in an HDI PCB stack-up are built using sequential lamination. This
process adds pairs of layers step-by-step, incorporating microvias and buried
vias at each stage to support complex interconnects.
Imaging and Etching
Take the high-res image to define
patterns for circuits first, and after that, etching to remove the excess
copper to get fine geometries of very precise traces. This process enables very
high-density routing in HDI PCB Design.
Solder Mask and Surface Finish
A solder mask is placed to protect the
traces, then a surface finish (like ENIG or HASL) is deposited on the pads to
ensure good solderability during assembly.
Testing and Inspection
Electrical tests are performed
rigorously on each HDI PCB, in addition to inspection with automated optical
inspection (AOI) to detect defects in the vias, traces, and connectivity. Thus,
all boards are assured to be of quality before delivery.
Why Choose PCBasic for HDI PCB Assembly?
PCBasic is the ultimate solution for top
quality HDI PCB assembly, in use by engineers and companies all over the world.
With a mix of technical knowledge and responsive service, we manufacture HDI
boards that are dependable and high-performance, on budget and on-time.
What Makes PCBasic Stand Out?
Specializing
in HDI PCB Technology: Expert handling of complex
HDI PCB stack-ups and microvia structures.
Fast
Prototypes of HDI PCBs: Fast turnaround aligned
with your project schedule.
Advanced
Manufacturing Equipment: Precision laser drilling,
AOI, and control processes are all solid and trusted guarantees for the highest
quality.
One-Stop
Service: From design support for HDIs to final
assembly, it is now under one roof.
Flexible
Volume: Whether for single HDI PCB prototypes or
volume production, we shall do it.
Reliably
On-Time Delivery: Speed comes first, quite not
compromising on quality.
Multi-Industry Experience: Automotive,
medical, consumer electronics, and industrial.
PCBasic
is the reliable HDI PCB manufacturer you can trust for
quality, precision, and performance.
Conclusion
HDI PCBs offer more than just being thinner
and lighter; they have become an important technology enabling innovations
across the sectors. From computer CPUs to smartphones and laptops, HDI
technology is used nearly everywhere. Its ability to deliver high performance
within a compact footprint makes it essential for modern, space-constrained
electronic designs.
All of the steps in HDI PCB fabrication
require as much expertise and precision as the design phase, advanced stack-up,
and precise manufacturing are a few of the most critical considerations.
PCBasic fits in here. As an established HDI
PCB manufacturer, we render complete services from HDI PCB prototyping to
full-scale assembly, thus bringing your designs to life with high quality, fast
turnaround, and reliability.
