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- Supports 0201, BGA, QFN, DFN, CSP
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Through Hole PCB Assembly
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A crucial factor in this miniaturization is Surface Mount Technology (SMT), which allows for more efficient and compact device designs. Surface Mount Technology (SMT) has revolutionized electronics manufacturing by enabling components to be mounted directly onto the surface of printed circuit boards (PCBs). This is a departure from the older Through-Hole Technology (THT), where components were attached by inserting leads into holes drilled into the PCB. As electronic devices became smaller and more sophisticated, THT gave way to SMT, which supports the development of smaller, more complex, and higher-performance devices.
What is Through Hole PCB Assembly?
Two Types of Lead Formats That Are Used for THT Components:
- Axial: Axial format has leads that run parallel to the wider axis. The leads of the components are opposite each other. Diodes are typical examples of axial components.
- Radial: Radial leaded packages have leads that are parallel and perpendicular to the wider axis. Transistors are typical components in radial formats.
Advancements in semiconductor packaging have led to the development of silicon planar technology, including the dual-in-line package (DIP) with multiple leads. These leads are pre-formed at a slight angle, enhancing stability and ease of insertion during the soldering process.
What are the Benefits of Through Hole Assembly?
Through-Hole Technology (THT) PCB assembly ensures robust connections between components, enhancing the PCB's resilience to environmental, thermal, and mechanical stresses.
THT is ideal for prototyping and rework because components can be easily inserted, replaced, or reinserted during product development. This flexibility makes it a valuable choice for iterative design and testing processes.
Through-Hole PCB assembly services are more cost-effective than Surface Mount Technology (SMT) for prototyping and small batch production. As a well-established manufacturing method, THT offers an economical solution for early-stage development and limited production runs.
In Through-Hole PCB assembly, there's no need to invest in costly pick-and-place machines; instead, you can use wave soldering or soldering irons. This makes the process more affordable and accessible.
Common Defects in PTH Assembly and How to Avoid Them
Through-Hole PCB assembly services are more cost-effective than Surface Mount Technology (SMT) for prototyping and small batch production. As a well-established manufacturing method, THT offers an economical solution for early-stage development and limited production runs.
Common Defects in Through Hole PCB Assembly
Here is a list of potential defects that through-hole PCB assembly manufacturers must carefully monitor and control to ensure high-quality production:
- Component Lifting: During the wave soldering process in through-hole PCB assembly, components may become disturbed, leading to lifting. Additionally, variations in lead length can contribute to component lifting, affecting assembly quality.
- Missing Components: This defect occurs when a component is missing from its intended location, often due to incorrect setup or improper picking and placement during PCB assembly. Missing components can typically be corrected in-line.
- Wrong Orientation: This defect occurs when a component is placed in the wrong orientation according to the PCB layout.
How to Detect and Avoid Defects in PTH PCB Assembly
- Sufficient Inspections Need to be Done: Inspection of these defects can be performed manually or automatically and is essential for ensuring PCB quality. Image processing techniques compare assembled boards to a reference image of a known good unit. Without thorough inspection, defective boards may pass to the next stage, causing test failures or, worse, be shipped to customers.
- Focus on Detection and Occurrence Controls: Quality control in through-hole PCB assembly should emphasize both detection and occurrence controls. Monitoring controls are essential for identifying frequent defects, typically analyzed with a Pareto Chart to highlight major issues. Root cause analysis is then necessary to address potential machine problems, process gaps, material quality issues, and production inconsistencies.
What are the Challenges of Through Hole Assembly?
Automatic component insertion machines are favored over manual processes in Through-Hole PCB assembly due to various challenges. Key issues to address during through-hole assembly planning include:
- Tight assembly tolerances are crucial for Through-Hole Technology (THT) and mixed THT/SMD techniques.
- Leads are susceptible to bending and deformation.
- Ergonomic challenges for manual assembly workers.
- Common defects in Through-Hole Technology (THT) PCB assembly include excess solder, bridging, de-wetting, and blow holes.
Processes Involved in Through Hole Assembly
Let’s explore the key steps in the through-hole PCB assembly process to gain a better understanding of this assembly technique.
Step 1: Component Insertion
The first step in through-hole PCB assembly is component insertion into the PCB holes or vias, typically done by automatic insertion machines. These machines handle both radial and axial components, offering high-speed insertion with varying pitch ranges and insertion directions. While manual insertion is an option, it is more labor-intensive and prone to errors.Step 2: Wave Soldering
Wave soldering is a process used in through-hole PCB assembly, where components are soldered by passing them through a wave of liquid solder. THT PCBs are placed on a conveyor with component leads protruding through the holes, ensuring proper wetting as they pass through the molten solder bath.Below are the key steps in wave soldering:
- Flux is applied using foam or spray techniques to remove oxides during the PCB assembly process.
- Flux activation is achieved by pre-heating the PCB, which also gradually raises the temperature to prevent thermal shock to the components during assembly.
- Components are soldered using the solder wave, where capillary action ensures a strong bond during the PCB assembly process.
Selective wave soldering is used in mixed SMT and THT PCB assembly to prevent damage to nearby SMT components during the soldering process.
Step 3: Cleaning
Flux enhances the soldering process by removing oxides that hinder wettability and preventing further oxidation by blanketing the surface. It also reduces surface tension at the joint interface. After wave soldering, flux residues remain and must be thoroughly cleaned.
Applications of Through Hole Assembly
Industrial Applications
Through-hole components are extensively utilized in industrial settings, such as robotics, circuit control systems, and sensor technologies.
Aerospace and Military
Through-hole PCB assembly supports large leads, making it ideal for high-current applications, particularly in aerospace and military equipment.
Commercial/Consumer Electronics
Through-hole components offer excellent electrical properties and are well-suited for high-frequency applications, including RF circuits.
Automotive Electronics
Through-hole PCBs are used in automotive engine systems, sensing, and control modules. Many electronics integrate through-hole technology with SMT for optimal design and performance.
ESPCBA: Your Trusted China Through Hole PCB Assembly Supplier
There are many through-hole PCB assembly manufacturers in China to choose from. The key question is: how do you determine if a supplier is reliable? Here’s why we are the trusted choice for your through-hole PCB assembly needs.
Low Cost
When selecting a reliable PCB supplier, cost competitiveness is crucial. Supplier pricing is influenced by the business model (turnkey or consigned), material choices, process flow, tooling requirements, packaging, and other expenses.
High Quality
Understanding the quality systems of a potential PCB supplier is crucial. Many issues related to poor quality may not become apparent early in a PCB project. The selected supplier must adhere to international standards and enforce strict process controls to ensure that only high-quality PCBs reach the end-user.
Technical Expertise
A China-based through-hole PCB assembly supplier with over 16 years of proven experience and technical expertise offers significant advantages. Key factors include the use of high-speed automated insertion machines and robust quality control processes. Additionally, strong engineering expertise is crucial for effective communication, risk management, project updates, and ongoing improvements.
On-Time and Quick Delivery
Delivery performance is crucial for through-hole PCB assembly services. It is influenced by factors such as geographic location, order quantity, processing steps, and cycle time. The supplier should offer fast lead times and consistently meet delivery commitments.
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