What is the PCB?
Printed circuit boards, or PCBs, are the essential component of most modern electronic devices. All other electronic components are assembled onto printed circuit boards, which can be as simple as the single-layered board in your garage door opener or as complex as the six-layer board in your smart watch or the 60-layer, extremely high density, high-speed circuit boards found in supercomputers and servers. Semiconductors, connectors, resistors, diodes, capacitors, and radio equipment are all mounted on the PCB and are all able to “talk” to one another.
Due to their superior mechanical and electrical properties, PCBs are the ideal option for these applications. Rigid PCBs are the most prevalent type in the world, accounting for around 90% of all PCB production today. Certain PCBs are pliable, enabling the circuits to be bent and stretched into desired shapes. Flexible circuits are also used in situations where they are expected to function properly after hundreds of thousands of bend cycles. These flexible PCBs account for around 10% of the market. Rigid flex circuits are a very small subset of these circuit types; they feature flexible regions that provide the previously discussed benefits of flexible circuits and firm parts of the board that are ideal for mounting and attaching components.
What is the PCB assembly?
PCBA refers to PCB assembly. The circuit board integrates different electrical components using a surface encapsulation process. The assembled PCB and outside case of the final product are joined by the box assembly, which is the following step. Put another way, the PCB bare board—also referred to as the PCBA—travels through the SMT top part before going through the entire DIP plug-in procedure. Unlike PCB’A, which adds a slant point as is customary in America and Europe, this method is extensively used in the country. Printed circuit board assembly is known as PCBA. Mass production for new electrical designs would usually come after prototype PCB assembly (Sample PCBA) to validate concepts, if a market is viable.
What are the differences between the PCB and PCBA?
The SMT technology is referred to by the words “bare circuit board” (PCB) and “circuit board plug-in assembly” (PCBA). One is a finished board; the other is a naked board. PCBs (Printed Circuit Boards), which are composed of epoxy glass resin, are classified into 4, 6, and 8 layers based on the quantity of signal layers. The most common counts of layers are four and six. Chip components, including as chips, are mounted to the bare board. A PCBA is equivalent to a completed circuit board, and it can only be manufactured once the manufacturing process for the circuit board is complete. Printed Circuit Board + Assemblies = PCBA.
Types of PCB Assembly
SMT assembly
BGA assembly
Mixed assembly
Rigid-Flex PCBA
Through-hole assembly
SMT assembly
The complete term for it is surface mount technology, or SMT. The SMT method is used to join parts or components to circuit boards. Due to its improved efficiency and better outcomes, SMT has supplanted other techniques in PCB assembly. PCB manufacturers used through-hole assembly primarily in the past to add components. That being said, SMT has replaced the prior method of assembly with welding technology. Additionally, PCBs manufactured by the SMT assembly technique are used by all electronic firms, including those involved in computers, phones, cellphones, home appliances, etc. AXI, AOI, reflow soldering, printing solder paste, and mounting components are all parts of the basic SMT assembly process.
BGA assembly
A ball grid array (BGA), also referred to as a chip carrier, is a surface-mount device used in the packaging of integrated circuits. BGA packaging is used for devices like microprocessors that are permanently installed. A dual in-line or flat package cannot have as many connector pins as a BGA. The device’s full bottom surface can be used, not just the edge. Furthermore, the traces that join the package’s leads to the wires or balls that join the die to the package are usually shorter than those of a perimeter-only type, which enhances performance at high speeds.
Mixed assembly
Certain components are still incompatible with SMT assembly, despite the fact that surface mount technology has replaced other mounting methods as the predominant method in PCB manufacturing. Then, SMT and THT assembly must be performed on the same board. A mixed assembly is defined as a combination of assembly methods that are produced without the use of solder paste.
While some specialized components that are not available in the SMT process require mixed PCB assembly, the majority of the components are welded in surface mount configuration on the board.
Rigid-Flex PCBA
Rigid-flex boards are printed circuit boards that combine the properties of flexible and rigid board materials. Most stiff flex boards consist of multiple layers of flexible circuit substrates attached to one or more rigid boards, either internally or externally, depending on the design of the application. Usually, during production or installation, the flexible substrates are shaped into the flexed curve and are meant to remain flexible continually.
Through-hole assembly
The through-hole assembly method is used to manufacture electronic circuits. Leads are used to install the components. It explains how to install the board by inserting the leads into the pre-drilled holes and soldering the components to the board using wave soldering or manual soldering.
From single-sided to double-sided to multi-layer boards, PCB design changed over time. Through-hole assembly is difficult to modify to meet the demands of modern electronics. Through-hole construction has virtually been replaced by SMT technology in today’s PCB fabrication. Through-hole installation is still necessary for some applications, including as those involving large transformers, connectors, and electrolytic capacitors.
SMT vs BGA vs Through-hole
It’s possible that through-hole technology works best for low-volume PCB manufacture (such as prototyping). Through-hole is usually seen to be the better choice for components that need to sustain significant stress since wire leads offer a strong connection. For front connectors—where USB cords and cables will be plugged in—the hole mounting approach is usually the recommended choice. But drilling holes increases the cost and lengthens the production cycle since it needs soldering on both sides of the PCB. Through-hole connectors might limit the amount of routing space that is available on multi-layer boards.
Modern electronic devices need to have several sophisticated features, efficient operation, and increased speed—all in a smaller package. The assembly must still be thinner even with additional electronic components. For these purposes, BGA packages are the greatest option. For example, BGAs are commonly utilized in the production of integrated circuits (ICs) with over 200 I/O connections. When production numbers are high, Surface Mount is a better choice since SMD components are smaller and result in a circuit board that is more compact and dense with components. SMT is a more reliable method than through-hole human assembly because SMDs may be automated with robotic pick-and-place devices, which eliminates the need for drilling. SMT is the industry standard technique for rear connections. SMT does have certain disadvantages. For instance, it is not advised to link high-stress components, and in order to produce it in large quantities, a costly initial investment in technology is required.
SMT is generally more economical and time-efficient.
