Through-Hole PCB Assembly by Omini

What is Through-Hole PCB Assembly?

The rapid evolution of electronics has transformed how we live, improving accessibility, transportation, and communication. At the core of electronic devices are Printed Circuit Boards (PCBs), which serve as the functional substrate where various components are mounted to work together seamlessly.

PCB assembly can be categorized by the method used to attach components. One popular method is Surface Mount Technology (SMT), where components are directly mounted on the PCB using solder paste. The other method is Through-Hole Technology (THT), primarily used in through-hole PCB assembly, where components are attached through pre-drilled holes on the PCB. In this article, we’ll focus on through-hole PCB assembly.

Through-Hole PCB Assembly involves attaching leaded components through holes drilled in the PCB. This process is similar to inserting a screw through a hole, but the component leads come in various sizes and shapes. The leads are inserted into the drilled holes and soldered on the opposite side of the PCB. A plated through-hole (PTH) is essential in this process, providing the necessary dimensions for the leads to be inserted securely.

Types of Lead Formats for THT Components
• Axial Leads: In this format, the leads run parallel to the component’s wider axis, with the leads positioned opposite each other. Common components with axial leads include diodes.
• Radial Leads: Radial leaded components have leads running parallel to each other at right angles to the wider axis of the component. Transistors are often found in radial lead packages.

With advancements in semiconductor packaging, dual-in-line packages (DIP) have become prevalent. These packages feature multiple leads that are pre-formed at a slight angle, making them more stable and easier to insert during the soldering process.

At Omini, we specialize in through-hole PCB assembly, providing reliable and precise solutions for your electronic manufacturing needs.

Processes Involved in Through-Hole PCB Assembly

To better understand the through-hole PCB assembly process, let’s explore the key steps involved in this assembly technique:

1. Component Insertion
The first step is inserting the components into the PCB holes (vias). This is done using an automatic insertion machine, designed to handle both radial and axial components. These machines offer high insertion rates and varying capabilities, such as pitch range, maximum speed, and insertion direction. While manual insertion is possible, it is more labor-intensive and prone to errors.

2. Wave Soldering
Wave soldering is used to solder the component leads to the PCB by passing the board through a wave of molten solder. This process ensures proper wetting and strong connections between the components and the PCB.

Key steps in wave soldering include:
• Flux Application: Flux is applied using foam or spray techniques to eliminate oxides and improve soldering.
• Preheating: The PCB is preheated to activate the flux and gradually raise the temperature to prevent thermal shock.
• Soldering: The PCB passes through a molten solder wave, where capillary action ensures the components are soldered to the PCB.

For mixed assembly boards with both SMT and THT components, selective wave soldering is used to protect nearby SMT components from heat damage.

3. Cleaning
After wave soldering, flux residues remain on the board. These residues must be cleaned off, as flux helps with soldering but can cause issues like corrosion and reduced conductivity if left on the PCB. The cleaning process involves rinsing the PCB to remove all flux residue, ensuring the board meets quality standards.

At Omini, we specialize in through-hole PCB assembly, providing precision and reliability for your electronic manufacturing needs.

Benefits of Through-Hole PCB Assembly

Despite the rise of SMT (Surface Mount Technology), through-hole assembly (THT) remains a preferred choice for certain applications, especially when combined with SMT. Here are the key benefits of through-hole PCB assembly that make it a viable option for many industries:

1. Mechanical Strength and Stability
Through-hole PCB assembly offers robust connections, ensuring that the PCB can withstand environmental, thermal, and mechanical stresses during operation. This makes THT ideal for applications requiring high durability and reliability.

2. Ease of Prototyping and Rework
THT is especially advantageous during prototyping and rework. Components can be easily inserted, replaced, or re-inserted during development cycles, making it a flexible option for product trials and modifications.

3. Cost-Effective for Small Batches
For prototyping and small batch production, THT assembly is more affordable than SMT, offering a more cost-effective solution for lower-volume runs. THT is a well-established and proven method, keeping production costs low.

4. Lower Investment Requirements
Compared to SMT, THT assembly requires less initial investment. There’s no need for costly pick-and-place machines; instead, wave soldering or manual soldering irons can be used, making it a more accessible option for small-scale production.

At Omini, we specialize in through-hole PCB assembly, providing reliable and cost-effective solutions for your electronic manufacturing needs.

Challenges of Through-Hole PCB Assembly

While automatic component insertion machines are commonly used to address the challenges in through-hole PCB assembly, several factors must be carefully considered during the planning and execution of the assembly process. Below are some key challenges associated with through-hole assembly:

1. Tight Assembly Tolerances for THT and Mixed Techniques
Achieving precise tolerances can be challenging, especially when combining THT (Through-Hole Technology) with SMD (Surface-Mount Devices) components. Strict alignment is crucial to ensure proper function and reliability.

2. Lead Deformation and Bending
Component leads are susceptible to deformation and bending during insertion and soldering. This can affect the quality of the connection and lead to potential defects if not properly managed.

3. Variability of THT Components
THT components come in various shapes, sizes, and configurations, making standardization and automation more complex. This variation can lead to challenges in handling and processing.

4. Ergonomic Issues for Manual Labor
Manual insertion can lead to ergonomic challenges, as the process is more labor-intensive and requires operators to work in repetitive motions, increasing the risk of strain or fatigue.

5. Common THT Assembly Defects
Through-hole assembly is prone to defects like excess solder, solder bridging, de-wetting, and blow holes, all of which can affect the integrity of the PCB. Proper quality control and testing are essential to prevent these issues.

At Omini, we leverage advanced automation and stringent quality control measures to overcome these challenges, ensuring reliable and high-quality through-hole PCB assemblies for your electronic manufacturing needs.

Applications of Through-Hole PCB Assembly

Through-hole PCB assembly remains a critical component in several industries due to its durability and reliability. Below are some of the key applications where through-hole technology is widely used:

1. Industrial Applications
Through-hole components are commonly used in industrial applications, such as robotic systems, circuit controls, and sensor technology, due to their robustness and high mechanical strength.

2. Aerospace and Military
In aerospace and military applications, through-hole PCB assembly is ideal for high-current applications, as it can accommodate large-sized leads for equipment and devices requiring enhanced performance and reliability.

3. Commercial and Consumer Electronics
Through-hole components are well-suited for high-frequency applications, such as RF circuits, in consumer electronics. Their excellent electrical properties make them ideal for devices where signal integrity is critical.

4. Automotive Electronics
Through-hole PCB assemblies are widely used in automotive electronics, particularly in engine systems and sensing and control modules. Often, through-hole technology is combined with SMT for optimal design and performance in automotive applications.

At Omini, we provide high-quality through-hole PCB assembly solutions tailored to meet the demands of diverse industries, ensuring reliability and performance in every application.

Common Defects in PTH Assembly and How to Avoid Them

Through-Hole PCB (PTH) Assembly must adhere to quality standards, such as IPC standards, to ensure optimal performance and reliability. However, due to the differences in materials, components, and processes between SMT and THT, each technology can experience unique defects. Understanding these defects and how to avoid them is crucial for maintaining high-quality output.

Common Defects in Through-Hole PCB Assembly
Here are some common defects that occur during through-hole PCB assembly:

1. Component Lifting
Component lifting occurs when components are displaced during the wave soldering process. Lead length variation, as well as factors like lead material, diameter, and hardness, can contribute to this issue.

2. Missing Components
Missing components happen when parts are absent from their designated locations. This defect typically results from improper setup or errors in the component placement process. Missing components can be identified and corrected in-line during assembly.

3. Wrong Orientation
This defect occurs when components are incorrectly oriented according to the PCB layout. Proper alignment during the insertion process is essential to avoid this issue.

How to Detect and Avoid Defects in PTH PCB Assembly

1. Conduct Regular Inspections
Regular inspections, both manual and automated, are vital for detecting defects early in the assembly process. Image processing techniques can be used to compare assembled boards with a reference “known good” image to spot potential issues. Without thorough inspection, defective boards may pass through subsequent stages or even be shipped to customers.

2. Implement Detection and Occurrence Controls
Quality control in through-hole PCB assembly should emphasize both detection and occurrence controls. Occurrence controls focus on monitoring and identifying the most common defects, often visualized using a Pareto Chart. By analyzing the top defects, root cause analysis can be performed to address underlying issues such as machine malfunctions, process gaps, material quality inconsistencies, or human errors.

At Omini, we prioritize high standards for PTH assembly and implement strict quality controls to ensure the best results, minimizing defects and optimizing manufacturing efficiency.

Omini: Your Trusted Through-Hole PCB Assembly Supplier in China

When choosing a China through-hole PCB assembly manufacturer, the key question is: how do you know if the supplier is reliable? Here’s why Omini is your trusted partner for through-hole PCB assembly:

1. Competitive Pricing
Cost-effectiveness is a crucial factor when selecting a PCB supplier. At Omini, we offer competitive pricing based on your business model—whether turnkey or consigned—and take into account material combination, process flow, tooling, and packaging. We strive to deliver cost-efficient solutions that fit your budget without compromising quality.

2. High-Quality Standards
Quality assurance is fundamental to our service. Omini adheres to international standards and implements strict quality control processes to ensure that every through-hole PCB assembly meets high-performance criteria. We take pride in delivering only the most reliable products to our customers, avoiding the pitfalls of poor quality that can arise in earlier project phases.

3. Proven Technical Expertise
With over 16 years of industry experience, Omini has built a strong reputation for technical excellence. Our team is equipped with automated insertion machines that provide high-speed, precision assembly. We also emphasize continuous engineering expertise, collaborating closely with customers to address risks, update projects, and explore improvements.

4. On-Time Delivery
At Omini, we understand the importance of timely delivery. We optimize our processes to meet tight lead times, ensuring on-time delivery without compromising on quality. We offer fast turnaround times regardless of order size, while maintaining high compliance with delivery commitments.