What Are PCBs Made Of? And How Do They Differ from Development Boards?

Printed circuit boards (PCBs) and development boards play a key role in the vast world of electronics and embedded systems. While both are key components in the design and prototyping of electronic devices, they serve different purposes and are built using different materials and techniques. This article delves into the materials that make up a PCB, explores its manufacturing process, and highlights the key differences between PCBs and development boards.

PCB 中使用的材料

PCB 是现代电子设备的支柱，为各种电子元件的互连提供了平台。它们通常由绝缘材料、导电层和焊接掩模组合而成。

绝缘基材：

The foundation of a PCB is its insulating substrate, often referred to as the base material or core. Commonly used substrates include fiberglass epoxy resin (FR4), phenolic paper, ceramic, and metal-based composites. FR4, due to its excellent electrical properties, mechanical strength, and cost-effectiveness, is the most widely used substrate material in PCBs.

Conductive Layers:

Conductive layers, usually made of copper, are etched onto the substrate to form the circuit patterns. Copper is chosen for its high conductivity, ductility, and resistance to corrosion. The thickness of the copper foil can range from a few microns to several millimeters, depending on the application.

Solder Mask:

A solder mask, typically a polymer coating, is applied to the PCB to protect the conductive traces and prevent unwanted solder bridges. It also improves the visual appearance of the PCB and makes it easier to identify components and traces.

Silkscreen:

Silkscreen, or legend printing, is the process of printing alphanumeric characters, symbols, or logos onto the PCB’s surface. This provides identification for components, test points, and other features.

Plated Through Holes (PTH) and Surface Mount Technology (SMT) Pads:

PTHs are metallized holes in the PCB that allow components with leads to be soldered on both sides of the board. SMT pads, on the other hand, are conductive areas on the surface of the PCB designed to accommodate surface-mounted components.

PCB Manufacturing Process

The PCB manufacturing process involves several steps, including substrate preparation, copper foil lamination, circuit pattern etching, solder mask application, and silkscreen printing.

Substrate Preparation:

The insulating substrate is cut to the desired size and shape, and then cleaned and prepared for copper foil lamination.

Copper Foil Lamination:

A thin sheet of copper foil is laminated onto the substrate using an adhesive. The thickness of the copper foil is determined based on the application’s requirements.

Circuit Pattern Etching:

A photoresist is applied to the copper foil, and a circuit pattern is exposed and developed using photolithography. The unprotected copper is then etched away, leaving behind the desired circuit pattern.

Solder Mask Application:

A liquid polymer is applied to the PCB, covering all but the conductive traces and pads. The solder mask is then cured, leaving behind a protective coating.

Silkscreen Printing:

The alphanumeric characters, symbols, or logos are printed onto the PCB’s surface using a silkscreen process.

Differences between PCBs and Development Boards

While PCBs provide the physical platform for electronic components, development boards are specialized PCBs designed for rapid prototyping and development. Here are some key differences between PCBs and development boards:

Purpose:

PCBs are designed to interconnect and support electronic components in a specific application. They are typically customized for a specific product or project. Development boards, on the other hand, are general-purpose platforms that provide a ready-to-use environment for developers to test and prototype their ideas.

Components:

PCBs typically contain only the minimum necessary components to support the desired functionality. Development boards, on the other hand, often come pre-loaded with a variety of components, including microcontrollers, memories, interfaces, and sensors. This allows developers to focus on their application’s functionality without having to worry about low-level hardware details.

Flexibility:

PCBs are highly customized and can be designed to meet specific requirements. However, once a PCB is manufactured, it is difficult to change its design or functionality. Development boards, on the other hand, provide a flexible platform that can be used for multiple projects. They also often come with programmable components, allowing developers to change their functionality through software.

Cost:

PCBs can be expensive, especially for low-volume production. The cost of manufacturing a PCB increases with its complexity and customization. Development boards, on the other hand, are typically mass-produced and therefore cost less per unit. However, they may not be suitable for high-volume production or cost-sensitive applications.

Ease of Use:

PCBs require a significant amount of time and expertise to design and manufacture. Developers need to have a deep understanding of electronics, circuit design, and manufacturing processes. Development boards, on the other hand, provide an easy-to-use platform that requires minimal setup time. They often come with documentation, examples, and community support, making them accessible to a wider range of developers.

总之，PCB 和开发板在电子设备的开发和原型设计中发挥着至关重要的作用。PCB 提供了用于互连和支持电子元件的物理平台，而开发板则为快速原型设计和开发提供了即用型环境。了解构成 PCB 的材料、其制造工艺以及 PCB 和开发板之间的主要区别可以帮助开发人员就其项目的最佳平台做出明智的决策。