What is HDI PCB design?

High-Density Interconnect (HDI) PCB design uses advanced interconnect structures and fine routing geometries to support greater connection density within a limited board area. Depending on the design and fabrication process, HDI construction can use microvias, blind vias, buried vias and sequentially laminated structures.

What is BGA escape routing?

BGA escape routing is the process of routing electrical connections from the pads of a ball grid array package into the PCB's routing layers. The strategy depends on package pitch, pad and via dimensions, layer count, electrical requirements and fabrication capabilities.

When is an HDI PCB required for a BGA component?

An HDI structure may be useful when a BGA has a fine pitch, a high pin count or routing requirements that are difficult to accommodate with conventional through-via construction. The decision should consider escape-routing feasibility, board dimensions, layer count, electrical performance, fabrication capability and total cost.

Do you support fine-pitch BGA PCB layout?

Fine-pitch BGA layout support can include footprint review, component placement, fanout planning, escape routing, layer assignment, via strategy and design-rule checking. The feasible routing approach depends on the package datasheet and the PCB manufacturer's design limits.

What is the role of microvias in HDI PCB design?

Microvias provide short interconnections between adjacent or selected PCB layers and can improve routing access in dense layouts. Their use depends on stack-up construction, reliability requirements, aspect ratios, lamination processes and the capabilities of the chosen PCB fabricator.

Can HDI and BGA PCB layouts support high-speed interfaces?

HDI and BGA layouts can support high-speed interfaces when the routing architecture is designed around the electrical requirements. Relevant considerations include controlled impedance, differential pair routing, reference-plane continuity, return paths, via transitions, timing constraints and power delivery.

What information is needed to start an HDI or BGA PCB project?

Useful project inputs include the schematic, component datasheets, BGA package and footprint details, board dimensions, mechanical constraints, interface requirements, target layer count, manufacturing limitations and any existing PCB design files. Fabricator-specific rules are also useful when selecting the via and stack-up strategy.

Can you review an existing HDI or BGA PCB design?

An existing HDI or BGA PCB can be reviewed using available schematic and layout files, stack-up information, package documentation and fabrication constraints. A review may examine escape routing, via placement, clearances, impedance constraints, power and ground routing, design-rule results and manufacturing readiness.

What deliverables can be provided for HDI and BGA PCB design?

Depending on the agreed scope, deliverables can include native schematic and PCB files, stack-up documentation, fabrication drawings, Gerber or other manufacturer-compatible outputs, drill files, bill of materials, assembly files and design-rule check results. Simulation reports and prototype validation results can be included when specifically covered by the project.

HDI & Fine-Pitch BGA PCB Design Services

Today's embedded devices are required to give higher processing power, connectivity and sensing function in smaller packages. The processors have hundreds of contacts placed on them and memory components should be placed close to the controller. Wearable gadgets and handheld computers require different approach to routing.

High-Density Interconnect, or HDI, PCB technology helps solve these challenges through smaller vias, finer traces, compact component placement and carefully planned multilayer structures.

Adequate Infosoft provides HDI PCB design and fine-pitch BGA layout services for industrial electronics, medical devices, cameras, wearables, robotics, automotive systems and connected IoT products.

Our engineers support hardware development from component selection and schematic review through layout, prototyping, board bring-up and manufacturing handover.

The goal is not simply to fit more components into a smaller area. A successful HDI design must remain electrically stable, thermally manageable, testable and practical to manufacture.

Let's Work Together!

What Is an HDI PCB?

Compared to regular circuits' boards, HDI PCBs offer a greater density. Technologies like microvias and the via-in-pad process, as well as blind, buried, and stacked vias and fine-line technologies in routing, can be used in their design and construction.

These new methods make it possible for engineers to connect various microprocessors.

Fine-pitch BGA packages create a particular routing challenge because their connections are arranged beneath the component. The BGA pitch, pad size, number of rows, signal allocation and fabrication limits determine how the connections can escape into the wider PCB.

HDI technology is useful only when it is supported by a realistic fabrication and assembly plan. Adding microvias without considering reliability, cost and supplier capability can make production more difficult rather than easier.

Our HDI and Fine-Pitch BGA PCB Design Services

HDI Stack-Up Planning

We create the PCB stack-up based on routing density, impendence, power distribution, and manufacturer capabilities.

The design considers the number of signal layers, the use of reference planes, thicknesses of core and prepreg, weights of copper, kinds of dielectric materials used, and cycling of lamination. In case of a sequentially laminated board, the design of the via structure should be agreed with the manufacturer prior to the routing stage.

We support multilayer structures for compact embedded systems, including boards that combine digital processing, memory, sensors, RF and power-management circuits.

Fine-Pitch BGA Escape Routing

It is the layout of the assembly from which the BGA escape strategy commences. We evaluate ball pitch, pad sizes, via technology, signal sets, and number of routing layers allowed.

In accordance with the usage, the escape method may incorporate dog-bone fan-out, blind microvias, via-in-pad plated-over designs or a combination of these methods.

Power and ground balls are not treated as leftover connections. Their vias and plane connections form part of the power-delivery network and influence voltage stability, return paths and heat transfer.

Microvia and Via-in-Pad Engineering

The benefit of microvias is that they provide routing pathways underneath small-pitch components and significantly decrease the area used by typically drilled vias. Via-in-pad is especially useful for high-density BGAs and thermal pads but needs to have a proper manufacturing process.

In preparation for assembly, some processes may be needed to fill, coat and level the vias. If this process is done incorrectly, solder will flow through the open via and create an unreliable connection.

We prepare via requirements with the chosen PCB supplier and avoid unnecessary complexity where a lower-cost construction can satisfy the design.

Signal and Power Integrity

Compact routing enhances coupling capabilities of clock and memory, RF, and power circuitry.

During the design stage, we check impedance constraints, consistency of reference planes, differential pair routing, length restrictions, termination, decoupling, and return current paths. We also pay attention as to where to place regulators, crystals, oscillators, and sensitive analog components.

Power integrity is particularly important beneath high-pin-count devices. Decoupling components must be placed according to package and device requirements, with short connections to the appropriate power and ground structures.

Thermal Management

A dense layout can concentrate heat within a small area. We plan copper spreading, thermal vias, component spacing and enclosure contact where required.

Thermal strategy is developed around realistic operating modes instead of component maximum ratings alone. Processing workload, wireless transmission, charging and environmental temperature can all affect actual board conditions.

Featured Case Study: HDI STM32 Terminal for a Confidential IoT Client

Phase 01 · Requirement

Client Requirement and Space Constraints

Adequate Infosoft was engaged by a client developing a specialized dual-mode IoT terminal. The client's company name is confidential, but the published project describes a compact device that could operate as a standard calculator and switch into a secured administrative terminal.

The final product design needed to stay in the thickness range of about 1.5 to 1.8 cm. The device must include a controller based on an STM32 chip implementing internal SMT, a button input matrix of 25 buttons, state indicators, safe firmware capability and a Wi-Fi or cellular connection.

If conventional printed circuit board design is applied, the product is likely to be thicker or to have an extra module outside the case. That is why the client wanted a high-density design based on co-design of mechanical and electrical components.

Phase 02 · Architecture

Four-Layer HDI Architecture

Our engineering team created a four-layer HDI PCB using a component-on-one-side strategy. The STM32 and supporting passive components were placed on the bottom, while the top surface was reserved for the 5 × 5 tactile-switch matrix.

With this arrangement, the switches could fit directly beneath the product overlay while ensuring that the processing electronics remained within the permitted internal height.

Microvia technology was employed to route the 25-key matrix without increasing the thickness of the printed circuit board. An internal ground plane acted as a reference thus ensuring that the controller and keypad signals are kept separate from switching noise generated by the external wireless link.

The layout also required careful treatment of the STM32 clock, power and programming connections. Decoupling paths were kept short, and access for firmware development and board bring-up was preserved despite the limited area.

Phase 03 · Wireless Expansion

Flush-Mounted Wireless Expansion

The external Wi-Fi or cellular dongle created both mechanical and electrical challenges. Mounting it conventionally would have exceeded the product's thickness target.

We incorporated a recessed USB/UART interface into the PCB cut-out allowing the dongle to rest inside the terminal profile. This design required collaboration on the board outline, connector alignment, enclosure design, and build process.

Cellular and wireless peripherals can create rapid load charge changes and generate signals at high frequency, thus requiring implementation of a special grounding and filtering system for the design.

Phase 04 · Validation

Firmware, Prototype and Validation

The hardware employed a special STM32 bootloader operating in two modes. The normal mode operated as a regular calculator while the administrator mode, controlled by a PIN, was designed to activate the secure interface and enable the wireless connection. The T9-style input method allowed entering complicated configuration content through the 25-buttons keypad.

A functional proof of concept was built in a CNC-machined enclosure to verify fit and thermal performance. Pre-scan EMC testing was also performed to assess whether switching activity from the wireless dongle interfered with the terminal logic.

The project demonstrates our ability to combine HDI routing, microvias, mechanical integration, embedded firmware and compliance preparation in one compact product-development workflow.

Relevant Projects That Demonstrate Our High-Density PCB Experience

Our experience is supported by published projects involving compact multilayer boards, dense processing hardware and demanding component integration.

Industrial Camera

1. AI-Powered Industrial Smart Camera

Adequate Infosoft created an effective AI camera to check goods on production lines for an industrial automation startup based in North America.

The project involved an eight-layer PCB of dimensions 90 mm x 70 mm created with the use of NXP i.MX RT1060, image sensor, DDR3 memory, eMMC storage, Edge TPU accelerator, Gigabit Ethernet, industrial I/O and power lighting control.

Creating the board required controlled-impedance MIPI routing, DDR topology planning, dense placement of components and thermal management under the processors. According to the records published, the project has successfully gone through the phases of prototype and preproduction and implementation phases.

Read the AI camera case study

Robotics

2. NVIDIA Jetson Orin Nano Robotics Carrier Board

For a warehouse automation project, our team created a six-layer carrier board supporting a NVIDIA Jetson Orin Nano module.

The board integrated MIPI CSI camera interfaces, USB, Gigabit Ethernet, CAN, UART, wireless expansion and multiple regulated power rails. It also included thermal provisions and EMC-focused grounding.

This project demonstrates experience routing dense embedded-computing hardware where high-speed interfaces, module connections, sensors and power circuits must coexist within one carrier platform.

Read the Jetson robotics case study

Rigid-Flex

3. High-Density ESP32-S3 Rigid-Flex System

Our ESP32-S3 endeavor combined a compact four-layer rigid control board with a smaller sized two-layer flexible circuit measuring 12 x 8 mm in size.

The primary board comprised of wireless, nf, usb-c, sd and rtc with fpc links wires in an approximate area of 30 mm x 80 mm.

Three devices were located on small flexibility part in a panelized process for SMT process. The project also involved three dimensional clearance checking with production files provided for selected assembly.

Explore the ESP32 PCB project

Wearable Hardware

4. Miniaturized Apollo MCU Wearable Hardware

Adequate Infosoft's Apollo MCU engineering skills include small wearable printed circuits made from components 0201 and 0402 as well as packages BGA/QFN and FPC.

All of these projects require low-power processing, biometrics, BLE, power management as well as small mechanical designs. The process of assembly includes verification of powering rails, testing of bus and checking of radio frequencies.

Explore our Apollo MCU development capabilities

Design for Manufacturing and Assembly of HDI

The manufacturing process goes hand in hand with the design of HDI circuit boards. In order to begin generating fabrication outputs, the essential guidelines must be communicated to the board manufacturer.

The major production considerations are the following:

Size of the microvias and the laser drilling process utilized;
The maximum permissible ratio in microvias;
Sequential lamination;
Methods of filling and capping the vias;
The minimum widths or clearances of the traces;
Copper positioning accuracy;
Capability of fine-pitch solder masking;
Surface finishing and flatness of the board;
BGA stencils and solder paste applications;
X-ray testing;
Panelization and the necessary assembly tools.

Design for testing is also vital. When the majority of the area of the boards consists of small components, it can be difficult to place the test points. However, there should be an opportunity for gaining access to power, programming, reset, communication as well as manufacturing diagnostics.

Finalizing Manufacturing Deliverables

The deliverables at handover of our contract would include editable schematics, proprietary PCB source files, library of electronic components, stack-up drawings, impedance tables, files for manufacturing, drilling files, assembly files, BOMs, approved alternatives, files for placing the components.

In the case of complicated devices, we would additionally include programming guidance, bringing the circuit board to running, requirements for factory checking, and record of revisions.

The ownership of design files and their licenses from third parties are specified in the contract, thus the client is aware of the documents to be provided at the end of the contract.

Give Details About Your HDI PCB Project

In case your product features a small-pitch microprocessor, FPGA, memory component or small wearable construction, provide all the details about the package, the schematic diagram, the mechanical limitations and the manufacturing tasks to Adequate Infosoft.

The team of Adequate Infosoft can help in developing an HDI architecture that strikes a balance between board dimensions, electrical characteristics, manufacturing possibilities, assembly efficiency and production costs.

Frequently Asked Questions

Does every fine-pitch BGA require an HDI PCB?

The answer is no. The type of board needed ultimately depends on ball pitch, pin count, PCB dimensions, and layering design. Conventional fan-out may be suitable for larger packages, whereas the use of microvias and via-in-pad technology may be necessary for smaller packages.

How many layers does an HDI board need?

There is no fixed number. Layer count depends on component density, BGA breakout, signal interfaces, power planes and EMC requirements. We select the simplest structure that meets the product’s technical needs.

Can you redesign an existing board around a smaller BGA package?

Yes. We can review the schematic, package, stack-up, enclosure and manufacturer rules before developing a revised placement and escape-routing strategy.

Do you support prototype assembly and BGA inspection?

Yes. We can coordinate prototype fabrication and assembly, including stencil planning, reflow requirements and X-ray inspection for hidden BGA joints where required.

Editorial Sources

Adequate Infosoft

Omkar Prayag

IPC CID+ Certified Hardware Designer

LinkedIn IPC CID+ Certification IPC CID Certificate

Leadership That Leads Worldwide

With a physical presence in over 15 countries and a global footprint spanning 25+ countries, we are ready to serve you anywhere. Location, language, or culture is never a barrier, because our global team can work with you in your language. Our strong international team ensures seamless collaboration across borders We have a strong tech team, highly recognized in their domains, with extensive technical expertise.

HDI & Fine-Pitch BGA PCB Design Services

What Is an HDI PCB?