What is PCBA and How to Custom PCB Assembly

PCBA is a printed circuit board assembly. It is an electronic mainboard or module created by soldering components on a blank PCB.

A PCB consists of insulating material sheets, copper foil, and solder masks. When it is soldered with the desired components and passes inspections, it is a PCBA.

The following is what this article reveals about PCBA:

Part 1: What is a PCBA?

PCBA, or Printed Circuit Board Assembly, is a term that refers to circuit boards with surface-mounted and/or through-hole-mounted electronic components, such as capacitors, resistors, inductors, and ICs.

A PCBA includes a PCB and components. A PCB uses conductive traces and pads that are etched from copper layers, which are laminated between the non-conductive sheet layers. The components are soldered on the PCB to connect electrically and mechanically.

To ensure that the connection between the PCB and components works adequately, solder is welded or inserted into a blank circuit board and inspected to test its performance.

In a PCBA, copper traces in different layers are interconnected by copper-filled holes, and the electronic components are soldered on the PCB copper pads or inserted through the copper-plated through-holes. A PCBA can have two component-mounting sides.

A PCBA is a semi-electrical product for almost every electronic device, from a small wearable earbud to a large industrial control system. When PCBAs are installed with enclosures and accessorial parts, they are box builds or final products. For example, the above image is a PCBA and its end product, a video projector.

Part 2: How Do You Get a Custom PCBA

In this section, we will have a look at how to create a custom PCB assembly.

Step1. The first step in designing a custom PCB is to create a schematic view.

The required components are placed on a canvas, and their pins are connected with lines that represent the electrical connections. The components are usually taken from a component library, which is a part of the design software.

There may be multiple variations of the same components depending on the type of package being used, e.g., a dual inline package or a surface-mounted chip. The packages may seem the same in the schematic view but are very different in the layout view where the board is designed.

Apart from the components and their electrical connections, power and ground signals are also needed. Also, connectors have to be placed on the PCB to provide a place for power and ground. The board is also required to be connected to external devices, such as potentiometers, LEDs, etc.

Step 2. Once everything is placed in its place, an electrical rule check is run to ensure there are no evident faults.

These may include breaks in wires or connections, or any missing connection to ground or power, etc. Once the schematic is done, the board layout view is checked.

Step 3. The components are moved to proper places that make sense.

Step 4. For board production, signals are assigned to each layer, and signals on a single layer cannot touch.

Step 5. After the signals are laid, a design rule check needs to run to ensure the proper placement of holes, traces, etc. These rules can be customized as well.

Step 6. If the design is approved, the design files can be uploaded.

The communication language of PCB fabrication is a Gerber file. Each board has multiple files, one for each layer. Another file, known as the "drill file," is used to define where holes need to be drilled.

Step 7. Send your Gerber, BOM, and pick-and-place file to info@pcbonline.com to get a PCBA quote. Please note that PCBA projects usually can't be quoted online unless they are standard PCBs with few components used for DIY or hobbyist uses.

Please tell PCBONLINE your PCBA project stage so that they can assign our work to fit your project.

The one-stop PCBA manufacturer PCBONLINE ensures customer satisfaction and reliability by offering professional design for manufacturing (DFM) and one-on-one engineering support. Besides, they purchase components from the source manufacturers, such as Texas Instruments in very large quantities, thus negotiating competitive prices. The PCBA pricing also goes down with an increase in the number of PCBAs.

Part 3: PCBA Manufacturing - SMT and PTH

Nowadays, almost all PCBAs require surface-mount technology, which is automatic. Through-hole technology (PTH), which is semi-automatic, is less in use.

SMT

Surface Mount Technology, or SMT, stands for the technology of soldering components onto the PCB surface. In SMT, the components, or SMDs, have no leads or only short leads.

The SMT assembly process is automatic and efficient. It includes solder paste printing on PCB pads, solder paste inspection, placing SMDs, reflow soldering, and automatic optical inspection (AOI).

SMT does not require the reservation of corresponding holes for the SMDs. It is suitable for high-density circuits. At PCBONLINE, the smallest SMD footprint is 01005, and the finest pitch (center-to-center distance between adjacent SMDs) is 0.05mm.

PTH

Through-hole PCB assembly, or PTH, means soldering component pins in through-holes on the PCB. THT is usually divided into single-ended, double-ended, and pin grid arrays.

Usually, the pins of the electronic components are inserted into the pre-set holes of the PCB manually. The PCBA is placed in a jig that exposes only the areas that need wave soldering and is preheated. Then, in the wave soldering oven, the THT component pins and the through holes are soldered.

If the PCBA requires different soldering specifications for different THT components, you will need selective soldering instead of wave soldering. At PCBONLINE, both wave soldering and selective soldering are available.

For mass PCBA manufacturing, SMT is more efficient and economical than THT.

Part 4: PCBA Inspections

Throughout the PCB assembly process, various inspections are required to ensure the robust connections and functions of the PCBA.

During PCB assembly, the PCBA inspections are:

• Solder paste inspection (SPI): After the PCBs are silkscreened with solder paste, they pass an SPI machine. Infrared cameras scan the solder paste, and the computer compares the specifications with pre-input standard specs to ensure that the size, thickness, and position of the solder paste are acceptable for soldering. Only after this inspection can the PCB go to the surface-mount devices (SMD) step.
• X-ray inspection for BGA: If the SMDs include ball grid arrays (BGA), the PCBA should pass the X-ray inspection before reflow soldering. This inspection ensures that the solder balls of the BGA are intact and adequate for soldering.
• Visual inspection: Before reflow soldering, every effort should be made to make sure nothing goes wrong. So there's a quality control (QC) group on the SMT line to check the surface of the PCBA.

• Automatic optical inspection (AOI): After reflow soldering, the PCBAs should pass through the AOI machine one by one to guarantee no soldering mistakes, including solder bridges, component offsets, solder voids, tombstones, etc.
• One more visual inspection: After the AOI, the QC group needs to check the PCBAs to ensure no component or board aging due to excessive reflow.
• First article inspection (FAI): In the PCBA prototype stage, 5 pieces are manufactured, and we randomly pick up one PCBA for the FAI. A specialized technician uses a probe pen connected to the FAI machine to touch the PCBA components one by one. The values of the PCBA components are recorded and compared with the pre-input ones. After the FAI, a report is generated automatically. We will send it to our client for review. Only with the client's approval can we start mass PCB assembly.
• Another two visual inspections: Before and after wave soldering, our QC technicians visually check the PCBA to make sure nothing goes wrong.

THT assembly is not the end of PCBA manufacturing at PCBONLINE. You can have the following PCBA inspections in the post-assembly stage.

• Multimeter inspection: In the PCB design stage, you will need to design pads for testing critical components on the PCBA using a multimeter. If you don't know how to do it or forget it, no worries, PCBONLINE will do it for you. After PCB assembly, we will use the two probes of a multimeter to touch the test pads to ensure the critical components on the PCBA are working. This is a necessary PCBA inspection.
• Functional testing: After PCB assembly, there is functional testing for the PCBA, which is an optional inspection. The PCBA is put on a jig that powers it on and connects it to a computer. The computer will display the pass results of the PCBA on the screen.
• Thermal aging: Thermal aging is a PCBA inspection that checks whether the PCBA can work adequately after a long period of continuous operation. The period lasts from 12 hours to 168 hours depending on the application requirements.
• Simulation test: After installing the enclosure, the PCBA is a box build or end product. To make sure the box build can work as expected, we can simulate the application field to see the working result of the product before delivery.

Besides, for flexible PCBs, the PCBA inspections include the tension test, bending test, hand sweat test, environmental protection test, metallographic inspection, bridge test, withstand test, and impedance test.

Part 5: PCBA Value-Added Services

After SMT and THT assembly, the bare PCB becomes a PCBA. However, it still needs some value-added services to extend the service life or load the IC with firmware before installing into an enclosure with wiring harnesses.

• Conformal coating: It is brushing or spraying a selective coating onto the surface of the PCB and components, usually acrylic, polyurethane, silicone, parylene, or epoxy. It insulates the PCBA from moisture, chemicals, and dust, and can reduce vibrations to the PCBA. At PCBONLINE, conformal coating is selective spraying, which is automatic and offers precision and reliability.
• IC programming: It is transferring the program into the bare IC, which can occur before or after PCB assembly. The program is downloaded on the computer first, then transferred to the IC. PCBONLINE also supports cloud transfer so that the customer controls the process and doesn't have to send the program to PCBONLINE.

Part 6. One-Stop PCBA Manufacturer - PCBONLINE

PCBONLINE provides one-stop PCB manufacturing and assembly. It focuses on EMS PCBA services, including PCB fabrication, component sourcing, PCB assembly, and electronic value-added services, including box-build assembly.

As a team of professionals building your PCBA, PCBONLINE ensures you make your work easy, efficient, and hassle-free.

Besides PCBA manufacturing, PCBONLINE provides IC programming, conformal coating, functional testing, thermal aging, and box-build assembly. If you have an interest in PCBA manufacturing, please contact info@pcbonline.com or chat with PCBONLINE from the online chat window on the right.

Part 7: Benefits of the PCBA

PCBA is a vital electronic semi-product of today's world. It offers several benefits, making it an important contribution to the modern world of electronics.

Time saver

It takes a lot of time for the traditional method of circuit connections to link the components. In contrast to traditional methods, the printed circuit board takes less time to construct a circuit.

Less cost with long-term reliability

In comparison with the traditional method, it costs less money and is more convenient for daily use, with maximum reliability for daily use.

Durability

The Printed Circuit Board Assembly does not have any wires that could be risky or tacky for the user. The traditional method has copper wiring for the interconnection of different components of the PCBA. This makes it much more durable and reliable.

Great compactness

The PCB offers a simple platform to arrange the components compactly and efficiently. Due to this, a large number of components can be easily arranged on our platform.

Easy to get repaired

If any circuit component fails to respond, you can easily replace it with a new one. This makes the process of installation easier and more convenient.

Part 8: Applications of PCBAs

PCBAs are used in various industries due to their vital role in the electronics world. PCBAs are crafted with a non-conductive material, on which copper sheets are spread. The use of PCBs in electronic devices is very common today, and there are different kinds of PCBs. They may be single-sided, multilayer, or double-sided. They may be rigid, flexible, or rigid-flex.

Industrial Applications

PCBAs are necessary for industrial electronics. The Internet of Things (IoT) is a trend in all aspects, and PCBAs play a vital role. In smart transportation, cars on roads are monitored by industrial cameras, and PCBAs are critical elements in cameras. In all kinds of factories, pressure sensors, temperature sensors, and moisture sensors use PCBAs.

Medical Sector

As innovations develop, the healthcare industry is using rising numbers of PCBAs, unveiling new capabilities. In devices used for diagnostics, tracking, treatment, and more, PCBAs play a major role. In many instances, PCBAs must also follow strict sanitation requirements, especially those used for implants. Like the machines that compile and interpret these images, CT, CAT, and ultrasonic scanners use PCBAs. To obtain accurate heart rate readings, blood pressure, and blood glucose, PCBAs are also key elements.

Automotive

PCBs were used mainly for items such as headlight switches and windshield wipers in the olden days, but now they support many advanced features that make driving safer and easier for a lot of people. Before you install a PCBA in your car, you should check that the specific part of the car for which you are using the PCBA will be able to resist extreme temperatures and vibrations.

Stereos and systems that incorporate navigation and entertainment do need PCBs. The engine management system and fuel regulators also rely on PCBAs.

Aerospace

There are similar specifications for electronics used in aircraft components to those used in the automotive industry, but aerospace PCBAs may be subjected to even tougher conditions. In a range of aerospace devices, including aircraft, satellites, space shuttles, and radio communications systems, PCBAs may be used.

To track the operation of the aircraft, pilots use different types of monitoring devices, including accelerometers and pressure sensors. Often, these displays use PCBAs.

Military

In defense applications, the military PCB assembly must be highly reliable and robust. PCBAs are required to operate radio communication systems and other essential communications. The control systems for different types of equipment, including radar jamming systems and missile detection systems, are based on PCBAs. Also, they enable indicators used by military members to track risks, execute military operations, and operate the equipment.

Consumer Electronics

PCBAs are helpful in smartphones, computers, and many other consumer goods that people use every day. PCBs with a large volume of connections are required to build small smartphones and laptops.

FAQ

What is a PCBA?

PCBA stands for printed circuit board assembly. It is a blank PCB soldered with the required electronic components. Once the components are soldered on and the assembly passes inspections, the PCB becomes a PCBA, ready to work as an electronic mainboard or module.

What is the difference between a PCB and a PCBA?

A PCB is the bare printed circuit board made of insulating material sheets, copper foil, and solder masks, with no components on it. A PCBA is that same PCB after all components have been soldered on and the assembly has passed inspections.

How do I get a custom PCBA?

Send your Gerber files, BOM, and pick-and-place file to info@pcbonline.com for a PCBA quote. PCBONLINE provides free DFM, DFT, and DFA reviews plus one-on-one engineering support, and accepts custom PCBA orders for prototypes, small batches, and mass production.

What is the difference between SMT and THT assembly?

SMT (surface mount technology) solders leadless or short-lead components directly onto the PCB surface through solder paste printing, placement, reflow soldering, and AOI. It suits high-density circuits. THT (through-hole technology) solders component pins inside drilled holes with wave or selective soldering. For mass production, SMT is the efficient and economical choice.

What inspections does a PCBA go through?

A PCBA goes through automatic optical inspection (AOI) after reflow soldering, visual inspections before and after wave soldering, first article inspection (FAI) at the prototype stage, and multimeter testing of the critical components. Optional inspections include functional testing and thermal aging from 12 to 168 hours depending on the application.

Wrapping Up

Suffice it to say that PCBAs have a diverse range of benefits and applications that indicate their important use in everyday life. Additionally, PCBAs are cost-friendly, which in turn makes it easier to use them in different industries. With applications across different technologies, PCBAs can be used in a wide range of situations.

PCBONLINE provides one-stop PCBA manufacturing reliably, on time, and cost-effectively. If you need to design and build an efficient and durable PCBA for your system, PCBONLINE is your best choice.

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