Can Printed Circuit Assemblys Withstand High Temperatures?

Printed Circuit Assemblys Withstand High Temperatures

As designers cram ever-more performance into printed circuit boards, they often raise the operating temperatures of these devices to meet the demands of their applications. But exposing PCBs to excessively high temperatures can cause the components and materials in a circuit board to degrade or even break down. The solder joints that connect the components to the board can also fail under these conditions.

PCBs are made from several layers of fiberglass and epoxy resin with copper traces and component leads soldered onto them. Each of these materials has a temperature limit beyond which they can degrade or break down. The temperature limit for FR-4 PCBs is 130-140°C, while specialized materials that are used in high-performance applications can tolerate much higher temperatures.

The most critical factor affecting the ability of a printed circuit assembly to withstand high temperatures is the glass transition temperature (Tg) of its substrate material. Tg is the temperature above which a substrate material will begin to degrade, which occurs as it begins to melt due to heat exposure. The Tg of a substrate is determined by its chemical composition and the process used to manufacture it.

Can Printed Circuit Assemblys Withstand High Temperatures?

Once a substrate has reached its Tg, it can be processed to form the base of a PCB, which is then coated with an adhesive that adheres to it and then etched to expose copper for soldering. The etching process can be performed manually or using automated equipment. Then a layer of solder mask is applied to the surface and finally, silkscreen is added for labeling.

One of the most important steps in PCB assembly is preparation of the materials and components for use with high-temperatures. This can involve spending a lot of money to buy new materials and components that can handle higher temperatures or by making adjustments to existing ones. The latter approach is usually more practical and cost-effective.

Another important step in preparing for high-temperatures is designing the layout of the PCB’s components to minimize stress and damage. This includes the order of placing components on the board and the placement of heat sinks to allow excess heat to be dissipated.

At its core, printed circuit assembly involves the integration of electronic components onto a PCB using advanced manufacturing techniques. The process typically begins with the fabrication of the PCB itself. Initially, a substrate material, commonly fiberglass-reinforced epoxy laminate, is chosen, onto which a conductive copper layer is deposited. This copper layer is then patterned using photolithography and etching processes to form the desired circuit layout, including conductive traces, pads, and vias. The resulting PCB serves as the foundation upon which electronic components will be mounted.

Finally, it is crucial to comply with industry standards and best practices throughout the PCB assembly process. Failure to do so can have serious safety implications and legal ramifications. By adhering to strict quality control standards, manufacturers can ensure that the finished product meets the requirements of their customers and regulators. By following these guidelines, manufacturers can also demonstrate their commitment to ethical and responsible manufacturing practices. This can boost their brand reputation and build trust with consumers, business partners, and regulatory bodies.