9 Must-Know PCB Assembly (PCBA) Equipment

Printed Circuit Board Assembly (PCBA) is the process of mounting electronic components onto a bare PCB to create a functional circuit board. This transformation from a blank board to a working device involves several intricate steps, each requiring specialized machinery. When a large number of PCBs have to be made, chances are that components won’t be manually soldered by hand. This is where professional assembly houses like PCBAStore will step in, to help fabricate both the bare boards and assemble all the parts onto the Printed Circuit Boards, or PCBs.

Let’s explore the essential equipment used in every stage of PCB assembly.

Stage 1: Paste Application

Solder Paste Printing Machine

The first step in PCB assembly is the application of solder paste onto the board. Solder paste is a gray-colored goo made from a mixture of tiny particles of metal alloys; usually of tin, lead and silver. It acts as an adhesive for surface mount components before they are permanently soldered.

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Before the paste is applied, a PCB stencil is placed over the board. The solder paste printing machine locks the stencil and PCB into place and uses a squeegee to apply solder paste precisely on the pads where components will be mounted.

Solder Paste Inspection (SPI) Machine

Numerous industry studies have pointed out that up to 70% of SMD soldering issues are traced back to improper or substandard solder paste printing. This makes SPI machines critical in high-volume production.

The SPI machine utilizes cameras capable of capturing 3D images, to evaluate the quality of the solder paste through factors such as solder volume, alignment, and height. When used together with Automated Optical Inspection , this enables manufacturers to effectively monitor and control the solder printing process, and therefore cut down on costs from rework and enable more efficient production of high-quality PCBs.

Stage 2: Automated Component Placement

Glue Dispensing Machine

Prior to component placement, the glue dispensing machine applies dots of glue onto the PCB where the body of the components will sit, to hold them in place until the leads and contacts are soldered. This ensures stability during processes like wave or double-sided reflow soldering.

Pick-and-Place Machine

The pick-and-place machine picks up components and places them onto a bare board. Pick-and-place machines suction up SMT components and place them accurately at their pre-programmed positions on top of the solder paste.

They are thrown down at lightning speeds, with machines easily achieving speeds of 30,000 components per hour. These machines provide unmatched precision and efficiency compared to manual placement.

Stage 3: Soldering

Reflow Soldering Machine

Reflow soldering is the most widely used soldering technique for PCB assembly. Once the board is fully populated with components, the assembly is moved along a conveyor, through a long, giant oven called the reflow soldering machine.

The conveyor system drives the circuit board through each set temperature zone in the equipment, and the solder paste is dried, preheated, melted, wetted, and cooled, and the components are soldered to the printed board.

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Reflow soldering has a series of advantages:

· More suitable for difficult assembly

· High welding quality

· Suitable for mass production

Wave Soldering Machine

Wave soldering machines got their name from the fact that PCBs have to pass over a wave of molten solder in order to solder the components. This method is primarily used for through-hole components.

At the start of the wave soldering process, a so-called flux layer is applied to clean all the component contacts and pads to ensure that solder can adhere properly. After flux application, the board is preheated to prevent thermal shock. Finally, a solder wave is set up within a tank of molten solder.

While less common today due to advances in SMT technology, wave soldering remains valuable for specific applications.

Stage 4: Inspection

Automated Optical Inspection (AOI)

With the increase in complexity of PCB boards, automatic optical inspection is more important than ever. AOI replaces manual inspection methods with automated systems that use high-definition cameras.

The AOI machine uses high definition cameras to capture the surface of the board and build up an image of it for analysis. This captured image is then compared with images of a correct reference board.

It helps detect missing or misaligned parts early in production.

In-Circuit Testing (ICT) – The Bed of Nails

Performed using a bed of nails fixture, the in-circuit testing (ICT) stage is one of the most widely recognized ways to quickly test functionality.

Each completed board is placed on top of these pins and pressed down. ICT allows fast verification by transmitting signals through hundreds of test points simultaneously.

Functional Validation Test (FVT)

Functional Validation Testing (FVT) is the final step that provides the go or no-go decision on completed PCBs before they are shipped.

Unlike previous tests focused on physical defects or connections, FVT simulates real-world usage. Software is loaded and we are testing whether the board will work as it should when it’s used in whatever application our customers have in mind for them.

FVT setups vary but always include hardware-software integration tailored per product requirements.

PCBAStore：Low-cost PCBA China PCB Assembly Services

If you’re looking for affordable yet reliable PCB assembly services from China-based providers like PCBAStore solutions offer significant value. From PCB design, layout to PCB prototyping, mass fabrication and then to PCB assembly, electronics box-build assembly services, our Printed circuit boards are widely built into robotics, medical, automobile, communication, industry and consumer electronics.We deal in the followings: Flex PCB, custom PCB, prototype PCB, turnkey PCB assembly, electronic PCB assembly, low volume PCB assembly etc.

PCBAStore includes additional benefits like free first-article testing and design checks which help minimize errors during mass production. Their turnkey service streamlines procurement along with assembly under one roof—ideal for engineers who want speed without sacrificing quality.

FAQ

Q1: What does “PCB Assembly” mean?
PCB Assembly refers to mounting electronic components onto printed circuit boards using automated or manual techniques depending on scale and complexity.

Q2: Why use SPI machines if I already have good printing methods?
SPI becomes crucial when producing large volumes because even small defects can lead to costly rework. It ensures consistent print quality across batches.

Q3: Is reflow better than wave soldering?
For SMT boards—yes. Reflow offers better precision especially with fine-pitch parts like BGAs. Wave remains useful for through-hole assemblies.

Q4: What’s unique about ICT testing?
It’s fast. ICT can check hundreds of points simultaneously using pogo pins—making it ideal for quick diagnostics during high-volume runs.

Q5: Do I need FVT if I already did AOI/ICT?
Yes. AOI/ICT check structural integrity; FVT ensures your product works correctly under real-world conditions including software behavior.