PCB Assembly Technologies

Printed Circuit Board Assembly (PCBA) is the process that transforms a blank PCB into a functional electronic circuit by mounting and soldering components onto it. PCB assembly and soldering complete the physical building of a circuit by picking, placing, and soldering components onto a board. There are three primary technologies used in this process: Through-Hole Technology (THT), Surface-Mount Technology (SMT), and Mixed Technology.

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Through-Hole Technology (THT) PCBA Process

In through-hole technology, leaded or pin-through hole electronic components are soldered to the board to make a circuit. The component leads are inserted into pre-drilled holes on the PCB and then soldered on the opposite side. This method provides strong mechanical bonds, making it ideal for components that may experience mechanical stress.

Surface-Mount Technology (SMT) PCBA Process

In PCBs using surface-mount pads, surface-mount devices (SMDs) are soldered to develop the circuit. Unlike THT, SMT does not require drilling holes; instead, components are mounted directly onto the surface of the PCB using solder paste. This allows for higher component density and miniaturization.

Mixed Technology PCBA Process

Such PCBs utilizing mixed components are called mixed technology boards, and the assembly process is a mixed technology PCBA process. As electronics become more complex, many designs incorporate both THT and SMT components. Mixed technology allows manufacturers to leverage the strengths of both methods in one board.

The Steps for Through-Hole Technology PCB Assembly

Each PCB assembly method follows a specific sequence of steps. Below is an overview of the THT assembly process.

Component Placement

In through-hole technology PCBA, the engineer starts by placing components in their respective positions as given in the PCB design files. Proper placement ensures that each component aligns with its designated pad or hole on the board.

Inspection and Rectification

After all the components are placed, an inspection is performed on the board. If the components are found to be placed inaccurately, such issues are rectified immediately through the rectification step. This step ensures accuracy before proceeding to soldering.

Soldering

The next step in the process is soldering, which fixes the components placed to their corresponding pads. Depending on production volume and requirements, various soldering techniques may be applied.

Testing

Once the PCB assembly and soldering process is complete, the board is taken for testing. Every PCB board used in an electronic device has gone through this process and passed testing.

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Soldering Techniques

Soldering is crucial to any PCBA process regardless of whether THT or SMT is used. Here are some commonly employed techniques:

Wave Soldering

Wave soldering is the most common technique used in THT and SMT PCBA. In wave soldering, a PCB is moved over a wave of hot solder liquid, which solidifies and fixes the components.

Braze Soldering

In braze soldering, metal components are attached through heating. This technique melts the metals at the bottom for fitting the filler metal. Braze soldering utilizes the highest temperature and produces the strongest joints.

Reflow Soldering

The reflow soldering process attaches components to the board using heated soldering paste. The soldering paste in its molten state connects the pads and pins in the PCB.

Soft Soldering

In the soft soldering technique, a metal space filler made of a tin-lead alloy is heated by an electric torch or gas to fix components to the board. Soft soldering is a popular technique for fixing compact, fragile components to a printed circuit board.

Hard Soldering

Hard soldering is used for combining metal parts such as copper, brass, silver, or gold at a temperature of about 600°F. Hard soldering produces stronger joints than soft soldering does.

PCBAStore：Low-cost PCBA China PCB Assembly turnkey Services

As the most popular PCB manufacturing and assembly company based in China ,we have been offering full spec electronic manufacturing solutions for 16 years, providing services from design to final box build. Our Printed circuit boards are widely built into robotics, medical, automobile, communication, industry and consumer electronics.

PCBAStore supports all types of pcb assembly including SMT-only boards, THT-only boards as well as mixed technology assemblies. We have advanced capabilities for SMT assembly, through-hole and mixed technology PCB assemblies to enable us meet all customers' PCBA needs under one roof in an inexpensive way.

With fast turnaround options like 24-hour express delivery for fabrication and 12-hour express service for assembly,PCBAStore offers rapid PCB prototyping services for quick-turn PCB at high quality and low cost. Their online quoting system allows customers to easily upload Gerber files or BOMs for instant pricing.

Quality assurance practices include visual inspections, AOI (Automated Optical Inspection), X-ray inspection for BGAs/QFNs,Functional Circuit Testing(FCT) is a quality assurance (QA) process, ensuring that every assembled unit meets IPC standards before shipping.

Customers benefit from flexible order volumes starting from just one piece up to mass production quantities.Our minimum is as low as 1 pieces. But we recommend our customers purchase at least 3 prototypes. Additionally,Passive Parts Free — Use our inventory turnkey orders of passive components, further reducing costs for prototyping projects. Get instant quote online.

FAQ

What’s included in turnkey pcb assembly?
Turnkey services cover everything from sourcing parts based on your BOM file to assembling them on fabricated boards. PCBAStore offers full Turn-Key and partial Turn-Key Circuit Board Assembly Services depending on customer preference.

How fast can I get my assembled boards?
Depending on complexity,Our service ranges from 8-Hour to 48-Hour. Note that production begins after all parts and files are received.

Do I need to provide all parts?
Not necessarily.We prefer you supply all parts. In this case please send us BOM file & packing list indicating item number & quantity. Alternatively,PCBAStore has a mature and effective components procurement systems serve turnkey orders with low cost.

What quality certifications do you follow?
PCBAStore adheres to ISO9001:2015 standards along with IPC-A-610F guidelines