什么是电子学中的印刷电路板？
印刷电路板的作用是连接、绝缘、排列和固定电子元件，以创建电路并传输信号和电力。例如，在印刷电路板上创建高频电路并将其用作天线。
这些都是用焊料表面安装在电路板上的。印刷电路板表面有一层涂层，可保护铜免受腐蚀，并减少短路的机会。这种涂层称为阻焊层。
什么是 PCBA？
PCBA 是印刷电路板组装的缩写。它是指将电子元件组装到印刷电路板上，以创建一个功能电子设备。这些元件包括
- 电阻器
- 电容器
- 二极管
- 晶体管
- 集成电路
- 和其他电子元件
印刷电路板组装过程包括将元件放置到印刷电路板上，然后进行焊接，以建立牢固的机械和电气连接。印刷电路板组装广泛应用于各种电子产品，包括
- 计算机
- 智能手机
- 电视机
- 医疗设备
- 汽车电子
Pcb 组装是制造功能性电子设备的关键。因此，它对电子行业的成功至关重要。
接下来，让我们来谈谈 PCB 与 PCBA。
PCB 与 PCBA 的区别
PCB 电路板和 PCB 组装之间有 3 个主要区别。
- 外观
- 制造工艺
- 制造成本
1.外观
PCBA 是焊接了所有电子元件的成品电路板，而 PCB 板则是裸电路。PCBA 是一种成品组件，其中包含电路板按预期运行所需的所有元件。
2.制造工艺
与印刷电路板组装相比，印刷电路板的制造工艺并不复杂。由于印刷电路板组装所需的零件和步骤繁多，制作空白电路板的复杂程度要低于制造成品印刷电路板组装。
例如，设计电路板、制作光掩膜、在电路板上蚀刻铜线以及涂抹阻焊层都是印刷电路板生产的常见步骤。另一方面，PCBA 制造除了涉及印刷电路板制造的所有阶段外，还包括将元件焊接到电路板上。
3.与 PCB 组装相比，PCB 成本大大降低
由于印刷电路板更容易制造，因此其价格低于印刷电路板组装。焊接到电路板上的元件种类和数量会影响 PCBA 的价格。
根据项目需要，您可以从裸 PCB 开始。随后，您必须咨询专业的 PCBA 制造商，为批量生产进行 PCBA 组装。
CBA 比手工组装的电路板更不容易出错。这是因为自动化生产流程非常精确且可重复
PCB 板和 PCBA 的优势
印刷电路板的优势
- 有了 PCB 板，电子设备的微型化就变得简单了，这使得制造商能够生产出更轻便、更紧凑的产品。
- 印刷电路板为电子元件提供了不间断的介质。最终，它降低了信号干扰的风险。
- PCB 板改善了信号传输和完整性
- Printed circuit board can effortlessly control heath coming from different installed components.
Advantages of PCB Assembly
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- PCB assembly provides a comprehensive assembly solution. For instance, there is no need to buy and assemble parts separately. This saves time and money.
- Automated production ensures high-quality PCB assembly. This is crucial for medical and industrial equipment performance.
- Due to the smooth automation process of component installation, there are minimum chances of errors in printed circuit board assembly.
PCB Vs. PCBA Manufacturing and Installation Process
The PCB board manufacturing process and PCB assembly are both crucial in terms of cost and efficiency.
Convert CAD data
We edit CAD (Computer Aided Design) data, which has been designed in advance to be used in manufacturing. In addition, the data converted for manufacturing is called CAM (Computer Aided Manufacturing), which is critical information when manufacturing printed circuit boards.
Make a hole in the board
Generally, drilling is performed to create mounting holes, through holes, and mini-via holes on the board. However, this is the manufacturing process’s most time-consuming and costly part. Similarly, we can reduce the cost by increasing the size or reducing the number of holes.
Additionally, with the miniaturization of materials, laser processing has become quite popular in recent years. They are making it possible to perform high-speed and high-quality processing. However, since laser processing uses high-density irradiation energy, it heavily burdens the resin.
Similarly, it is not suitable for processing through holes. Therefore, it is necessary to consider and select the appropriate processing method. Generally, it depends on the type of PCB board and the wiring pattern.
Forming a Copper Foil Pattern
Once the hole-drilling process is complete, copper foil is applied to the entire board to form the pattern. Creating a copper foil pattern requires several steps. Similarly, it is a fundamental process in manufacturing printed circuit boards.
Generally, the process is divided into two steps: exposure and etching, and each procedure is performed using the following steps.
Exposure
Exposure is transferring pattern data converted to CAM onto a substrate. In this process, we use a dry film on a substrate coated with copper foil. Similarly, we apply a photosensitive agent called resist over the dry film. Furthermore, an artwork film with a pattern drawn on it is pasted on top and exposed to ultraviolet light.
Etching
Etching is a method of chemically removing copper foil by spraying chemicals onto the PCB board, etching the exposed substrate, and removing the copper foil from areas other than those covered by the hardened resist.
The copper foil remains in the same shape as the pattern. Finally, by peeling off the dry film using chemicals, we achieve the copper foil pattern according to the design data. For multilayer PCB boards, repeat the same process with an insulating layer crimped in between.
Form solder resist
If the copper foil pattern is left exposed on the board surface, there is no insulating film, and problems will occur. For example, wiring and electronic components will short out. Hence, we apply solder resist to form an insulating film. Its function is to protect the copper foil pattern.
Soldering
Generally, we place the PCB board in a tank of high-temperature molten and solder liquid. Once the entire board is coated with solder liquid, use high-temperature, high-pressure hot air to smooth the solder liquid to a uniform thickness.
This method allows efficient component mounting. Soldering also prevents oxidation of the parts where we mount components and the copper foil.
PCB Assembly Component Installation Process
There are three methods for component installation in PCB assembly. These are:
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- Through-Hole installation
- Mixed Assembly
- Surface Mount Assembly
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Here, we shall focus on surface mounting assembly process.
1. Solder Paste Printing
In solder pasting, we use a cream solder for printing. We use a jig called a metal mask to separate the areas that require printing. It is to prevent cream solder from being printed on unnecessary areas.
Generally, we use Gerber data to create the metal mask used in this process.
Bond Application
The chip bonding process is a process in which a bond is applied to secure chip components. Its primary role is to fix parts so they do not fall” when mounting components in the flow soldering process.
Another use is to cover extra parts insertion holes with adhesive to prevent manual insertion errors.
Component Installation
This is the process of actually mounting chip components. Chip-mounted components are mainly delivered as reels and then set into cassettes.
By attaching the cassette to the designated location on the mounter, you are ready to mount the component on the PCB board.
2. Reflow oven
This process applies heat to the mounted board to blend the mounted components, chips, and solder.
Each is heated for the following purposes:
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- Cream solder
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Cream solder is melted by heat and blended with the parts.
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- Chip bonding
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Cures the bond using heat and fixes the component so it cannot be removed until the mounting process.
The melting temperature of the cream solder and the curing temperature of the chip bond are different.
Therefore, depending on the process, we adjust the temperature to an appropriate temperature and place as little stress on the board as possible.
3. AOI Inspection
The inspection process in PCB assembly is to check the quality of components installed on PCB board. It is a critical step to check potential errors before it goes for reflow soldering. For this process, PCB assembly manufacturers use AOI machines. Similarly, First Assembly Inspection is also important before the product goes into the mass production.
4. Reflow Soldering
Once the surface mounting process is complete, components are manually inserted into the PCB board using a reflow soldering process according to specifications. The major function of this process is to establish a connection between PCB board and all components.
5. Post Flow Inspection
It is the last stage in printed circuit board assembly. The purpose of this visual inspection to ensure that there is no mistake in the product. Now, PCB assembly companies are using 3D technology which can detect such errors significantly.
Summary
The primary difference between PCBs and PCBAs lies in their respective compositions. Printed circuit boards are fully designed boards with wiring patterns. In contrast, PCBAs, are fully assembled boards that incorporate all necessary electronic components.
One prominent distinction is in the manufacturing process of PCBs, which is predominantly carried out in large quantities. Similarly, we can execute PCBAs in either small or large quantities.
Please contact Kingsun PCB, which has 20 years of experience in printed circuit board assembly and provides high-precision, high-quality products and technical know-how.