Introduction

At LHD TECH, we recognize that through-hole assembly remains an indispensable part of modern pcb assembly techniques. Even as surface mount technology (SMT) continues to evolve, the superior strength, durability, and reliability offered by through-hole assembly make it the preferred choice for high-power, high-stress, and field-repairable applications. Whether you are developing industrial control systems, automotive electronics, medical equipment, or ruggedized devices, LHD TECH provides expert through-hole assembly services designed to meet the most demanding performance standards.

What is Through Hole PCB Assembly?

Through-hole technology (THT) is a time-tested pcb assembly technique in which  electronic components leads are inserted into pre-drilled holes on the PCB, then components are soldered onto pads . This process requires both an electrical connection and a strong mechanical bond, ideal for components subject to vibration, thermal stress, or frequent handling.

We specialize in both manual and automated through-hole PCB assembly, supporting axial, radial, DIP, and large-form-factor components to ensure your designs achieve optimal reliability and longevity.

How Does the Through Hole PCB Assembly Process Work?

We execute a meticulous, through-hole assembly process to ensure every board meets the highest standards of integrity and performance of this pcb assembly technique:

1. Design and Drill Preparation

Our process begins with partnership. We work with your design team to review through-hole components selection(axial and radial components) and pcb board layout, ensuring optimal drilled hole diameter, annular ring geometry, and thermal relief. Our Design for Manufacturing (DFM) feedback prevents issues before production begins.

2. Involves Drilling Holes and Soldering

Using state-of-the-art CNC drilling equipment, we create clean, accurate holes in your PCB substrates and component placement. For multilayer PCBs, these holes and pads become robust plated-through vias, ensuring secure layer-to-layer connectivity.

3. Component Insertion & Mounting

Depending on your mounting electronic components’s scale and complexity, we employ either high-speed automated through-hole assembly machines for volume runs or skilled technicians for prototypes, low-volume, or complex assemblies. We handle everything from axial leaded components on the board and radial lead components and large DIP ICs.

4. Soldering Process

For pure through-hole boards, our wave soldering process systems deliver consistent, high-quality joints. For hybrid boards combining SMT and THT, we utilize precision selective soldering—a LHD TECH specialty—that targets only the flow into the hole areas, protecting sensitive surface-mount circuit board and its components from thermal stress.

5. Trimming and Cleaning

Excess leads are cleanly trimmed after components are soldered, and boards undergo thorough cleaning to remove flux residues—critical for high-reliability electronics and medical applications.

6. Inspection and Testing

Quality is ingrained at every step. We employ AI-enhanced Automated Optical Inspection (AOI), X-ray for hidden joints, and skilled technician audits with PCB testing. Every connection is tested for electrical integrity, ensuring the through-hole PCBs matches your design intent perfectly.

Types of  Through Hole Components

LHD TECH has the mounting process expertise and equipment to handle the full spectrum of through-hole components:

1. Axial Components

• Axial leaded components(like resistors or diodes) have leads emerging from each end.
• These parts lay flat across the PCB, good for minimizing profile height, and are easy to handle during assembly.

2. Radial Lead Components

• Radial lead componentshave both leads sticking out one side, so they stand upright on the PCB.
• Radial capacitors, LEDs, and varistorsare prime examples.

3. Dual In-Line Package (DIP) Components

• Classic for ICs, relays, and sockets.
• DIP components are specifically designed for hole PCB assembly and are popular in prototype boards and socketed systems.

4. Connectors, Transformers, and Power Devices

• Large components that must endure mechanical stress or repeated connection cycles almost always leverage through-hole mounting for longevity and repairability.

Through-Hole Mounting and PCB Assembly Techniques

Modern pcb assembly techniques for through-hole leverage both manual and automated assembly. Through-hole mounting is superior for specific needs:

• Assembly offers secure, vibration-resistant connections.
• The assembly process allows for larger parts and higher power ratings than SMT.
• Hole and surface mount components may coexist, forming today’s hybrid circuit boards.
• Hole assembly services now offer rapid switching between high-mix, low-volume builds and full automation for standard parts.

Innovations and Automation in Assembly Services

Automated Through-Hole Assembly: Our production lines are equipped with modern robotic insertion systems and selective soldering machines, enabling efficient high-volume runs as well as flexible low-volume, high-mix projects.

Selective Soldering: We expertly manage hybrid PCB assemblies that combine both through-hole and surface-mount components on the same board.

Lead-Free & RoHS Manufacturing: LHD TECH supports RoHS-compliant, lead-free alloys means the process creates boards with minimal environmental impact, realize to supporting eco-friendly electronics manufacturing.

AI-Driven Inspection and Data Logging: Our AOI and X-ray systems are powered by AI-driven defect detection, ensuring real-time quality monitoring and consistent output.

Prototyping Capabilities: From your digital design files to a fully assembled, tested prototype, LHD TECH delivers fast-turn through-hole assembly to accelerate your development cycle.

Best Practices for Circuit Board and Its Components

At LHD TECH, we believe that excellence in through-hole assembly isn’t accidental—it’s engineered through rigorous standards, disciplined processes, and deep expertise. Here is how we translate industry best practices into guaranteed results for your circuit boards and components.

• Partner with Certified Experts

*Entrust your designs to an IPC-A-610 and ISO-certified work with trusted PCB assembly services.* We don’t just comply with these standards; we build our culture around them. Our certifications are your assurance that every board we produce meets globally recognized benchmarks for workmanship and reliability, from commercial (Class 2) to high-reliability aerospace/medical (Class 3) applications.

• Design for Manufacturability (DFM) from the Start

Component datasheets are our blueprint. Our engineering team proactively reviews your BOM and layouts, verifying lead forming, insertion depth, and pad-to-hole ratios for all axial and radial components. We provide actionable DFM feedback before production begins, minimizing potential for failures and ensuring optimal performance.

• Prototype with Precision Checkpoints

Catch issues early, optimize iteratively. For prototype runs, we implement structured checkpoints after insertion, soldering, and trimming. This phased verification allows for immediate correction and collaboration, turning your prototype phase into a powerful refinement tool, not just a proof-of-concept.

• Invest in Superior Materials & Calibration

The integrity of a solder joint is only as good as the process behind it. We use only high-quality, certified fluxes and alloys. Our soldering stations and automated systems are maintained under a strict calibration schedule, ensuring that every connection perfectly wets the plated through-hole without compromising its integrity.

• Cultivate a Culture of Expert Excellence

Our technicians are our first line of quality defense. Through continuous training, our team is adept at recognizing subtle defects—from insufficient fill to cold joints. We foster a culture of continuous improvement where every team member is empowered to uphold and advance our quality standards.

• Maintain Peak Performance in Automation

Consistency at scale requires impeccable machinery. Our automated insertion, selective soldering, and wave soldering systems undergo rigorous preventive maintenance. Furthermore, our advanced AOI and X-ray inspection setups are dynamically recalibrated for new board and component variants, ensuring our automated scrutiny is always as precise as our assembly.

Partner with LHD TECH for Unshakeable Foundations

In the fast-paced world of electronics, the need for unwavering reliability has never been greater. LHD TECH’s Through-Hole pcb assembly services delivers the robust, serviceable, and durable foundation your most critical products require. We blend time-tested techniques with modern automation and inspection to provide a service that is both reliable and advanced.

Let us help you build something that lasts. Contact LHD TECH today to discuss your through-hole assembly project and experience the strength of precision partnership.