How Do Printed Circuit Assemblys Handle Thermal Expansion?

Printed Circuit Assemblys Handle Thermal Expansion

Printed circuit boards require a series of complex and precise steps to be constructed. These steps are essential to ensure that a device will function properly, and they help to minimize risks such as faulty connections and malfunctions. To achieve this goal, the PCB assembly process must be performed meticulously and with strict quality control measures at every step of the process.

When creating a printed circuit assembly, technicians must carefully plan out its layout to include all necessary components and to account for the way the materials will expand and contract as they heat up during operation. This is called thermal expansion, and it can have serious effects on the design of a circuit board.

For example, a copper layer will change shape as it experiences varying temperatures. This is due to its coefficient of thermal expansion, or CTE. Knowing the CTE of each copper layer helps to ensure that the layers will be aligned when soldered together. If the layers are misaligned, it can result in warping of the board and damage to its components.

How Do Printed Circuit Assemblys Handle Thermal Expansion?

In addition to the CTE, there are other factors that must be taken into account during the assembly of a printed circuit board. For example, a component’s lead length can also influence how the board will respond to thermal expansion. For this reason, it is important to choose components with the correct leads for your project.

Another crucial consideration is how the components will be affixed to the PCB. There are several different methods that can be used, depending on the type of components you need and your assembly method. These include through-hole technology (THT) and surface mount technology (SMT). Through-hole technology involves placing components through holes on the PCB, while SMT places components on the surface of the board using a stencil.

Both of these processes can be assembled by hand or using automated equipment. While there is a place for a human touch, automation allows the technician to focus on other aspects of the assembly process. For example, a pick-and-place machine uses mechanical or even vacuum-based movements to take a component from a feeder and put it onto the board in its correct position. This allows for higher production speeds and reduces the chance of human error.

Once all of the components are placed on the PCB, it’s time for soldering. Soldering melts a metal alloy at high temperatures to bind the components to the board, ensuring strength, durability, and longevity. A common soldering technique is reflow soldering, which uses a heated chamber to melt the solder paste and affix all of the components to the printed circuit board.

Lastly, the completed PCB will undergo functional testing to confirm that it is working correctly. This step is especially critical to identify any issues that can impact the functionality of the device, such as a lack of connectivity or a decrease in product lifespan. The successful completion of this test is dependent on the quality of the components and assembly process, so it’s imperative that you work with a supplier that adheres to industry standards.