Complex PCBA Assembly with SMT and Through-Hole Components -Hitech Circuits
This PCBA showcases a complex electronic assembly combining surface mount components and a large number of through-hole components. With multiple connectors, terminals, capacitors, resistors, ICs, and other electronic components assembled on the board, this type of PCBA requires careful control throughout the entire manufacturing process.
For electronic products with a high component density and many through-hole parts, PCB assembly is more than simply placing components on a circuit board. Component selection, PCB design, soldering methods, component orientation, and inspection all need to be carefully coordinated to achieve stable and reliable assembly quality.
SMT and Through-Hole Assembly on One PCBA
Many electronic products cannot be manufactured using SMT assembly alone. While surface mount technology is suitable for compact components and high-density PCB designs, through-hole components are still widely used for connectors, terminals, switches, transformers, large capacitors, and components that require additional mechanical strength.
The PCBA shown in the image uses a combination of SMT and through-hole technology. SMT components are mounted directly onto the PCB surface, while through-hole components are inserted through drilled holes and soldered to the board.
This mixed-technology approach is commonly used for industrial control boards, power electronics, communication equipment, instrumentation, control systems, and other electronic products where both electrical performance and mechanical reliability are important.
Why Through-Hole Components Require Careful Assembly
A PCB with a large number of through-hole components can involve more assembly steps than a standard SMT board.
The component leads need to be inserted into the correct holes according to the assembly drawing and component orientation. Components with polarity or specific installation directions must also be carefully controlled during assembly.
Depending on the PCB design and component type, through-hole components can be assembled using different methods, including manual insertion, selective soldering, wave soldering, or manual soldering.
For complex PCBA projects, the appropriate process needs to be selected based on the component structure, PCB layout, production quantity, and soldering requirements.
Component Sourcing Is Also Important
For a PCBA containing a large number of different components, component sourcing can have a significant impact on production.
A typical PCBA BOM may contain dozens or even hundreds of different part numbers. Some components may be readily available, while others may have longer lead times or limited market availability.
Before production, a PCB assembly manufacturer should check the BOM carefully and confirm:
Manufacturer part numbers
Component specifications
Package types
Component availability
Lead times
Approved alternatives
Quantity requirements
Special component requirements
For customers who require a turnkey solution, PCB fabrication, component sourcing, and assembly can be managed by one supplier. This can simplify project communication and reduce the number of suppliers involved in the manufacturing process.
PCB Assembly Process for Complex PCBA
For a mixed SMT and through-hole PCBA, the manufacturing process normally includes several stages.
First, the bare PCB is manufactured according to the customer's Gerber files and technical specifications. The PCB may include multilayer construction, controlled impedance, different copper thicknesses, or other special requirements depending on the application.
After PCB fabrication, components are prepared according to the BOM.
For the SMT section, solder paste is printed onto the PCB using a stencil. Components are then accurately placed by a pick-and-place machine before entering the reflow oven.
After SMT reflow, the assembled board can be inspected using AOI (Automated Optical Inspection) to check component placement, polarity, soldering conditions, and other visible assembly defects.
The through-hole components are then inserted and soldered according to the required production process.
For boards with many connectors and other through-hole components, soldering quality is particularly important because these components can experience mechanical stress during the customer's final product assembly and daily use.
Inspection and Quality Control
Inspection is an important part of PCBA manufacturing, especially for complex boards with a combination of SMT and through-hole components.
AOI can be used to inspect the SMT assembly for issues such as missing components, incorrect component placement, polarity errors, and visible soldering defects.
For assemblies containing BGA or other hidden solder joints, X-ray inspection may also be used when required.
Through-hole solder joints can be inspected visually or with other appropriate inspection methods depending on the component and PCB structure.
For some products, electrical or functional testing is also required after assembly. Functional testing can help verify whether the finished PCBA operates according to the customer's requirements.
The inspection method should be selected according to the actual PCB design and application rather than applying the same inspection process to every PCBA project.
Suitable for Industrial and Electronic Equipment
PCBA designs with a large number of through-hole components are still widely used in many applications.
Typical applications include:
Industrial control equipment
Automation systems
Power supplies
Communication equipment
Measurement and testing equipment
Control panels
Instrumentation
Security equipment
Medical and laboratory equipment
Specialized electronic devices
Through-hole components can provide strong mechanical connections, making them suitable for components that may experience repeated insertion, vibration, or mechanical stress.
For example, connectors and terminal blocks are often designed as through-hole components because they need to withstand mechanical forces during installation and use.
From Prototype PCBA to Production
The manufacturing requirements can vary depending on the production stage.
For a prototype PCBA, the main focus is often on verifying the design, component compatibility, assembly process, and product functionality.
During low-volume production, manufacturers need to maintain flexibility while ensuring consistent assembly quality.
For mass production, stable component sourcing, process control, production efficiency, and quality consistency become increasingly important.
A PCBA manufacturer with both PCB fabrication and assembly capabilities can support the project through different stages, from prototype development to production.
Choosing the Right PCBA Manufacturer
When selecting a PCB assembly supplier for a complex board, it is important to look beyond the assembly price.
The supplier should have suitable experience with the PCB technology, component types, soldering requirements, and production volume of the project.
For PCBA projects containing many through-hole components, customers may also want to consider the manufacturer's capabilities in:
SMT assembly
Through-hole assembly
Selective soldering
Wave soldering
Manual soldering
Component sourcing
AOI inspection
X-ray inspection
Functional testing
PCB fabrication
Prototype assembly
Low-volume production
Mass production
Good communication during the engineering and quotation stage is also important. Potential issues with the BOM, PCB design, component availability, or assembly process can often be identified before production begins.
Hitech Circuits PCBA Manufacturing
Hitech Circuits provides PCB fabrication, PCB assembly, and PCBA manufacturing services for customers requiring prototype, low-volume, and production quantities.
Our capabilities include SMT assembly, through-hole assembly, component sourcing, turnkey PCB assembly, AOI inspection, X-ray inspection, and functional testing.
For complex PCB assemblies with a combination of SMT and through-hole components, our team can review the PCB files, BOM, assembly drawings, and other production documents before manufacturing.
Whether your project requires a compact SMT board or a larger PCBA with numerous connectors and through-hole components, the assembly process can be tailored to the requirements of the product.
Contact Hitech Circuits to discuss your PCB assembly project and PCBA manufacturing requirements.
Mobile/Whatsapp/Skype:+86 18033052718
Email: sales10@hitechpcb.com
Website: www.hitechpcba.com
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