Substrates Used in Rigid-Flex PCB Manufacturing
Rigid-flex circuits combine rigid sections and flexible ones to create the structure of a printed circuit board. They’re typically used in applications that need a combination of flexibility and stability, like high-speed electronic components and industrial machinery. The substrates that form the base of a rigid-flex PCB are crucial for ensuring its reliability and longevity. Choosing the right materials is critical for ensuring that the circuit can meet your design and operational needs. In this article, we’ll take a look at the most common types of substrates that are used in rigid-flex PCB manufacturing.
Rigid flex boards consist of multiple layers, each with specific electrical and mechanical properties. To maximize the strength and flexibility of these boards, the substrates must be made of durable, high-quality materials that can withstand constant movements and vibrations. Several factors can influence the type of substrate material that is best for a particular application, including its chemical and thermal resistance, dimensional stability, and electrical properties.
The most popular substrate for rigid flex pcb manufacturer is Polyimide film, which offers excellent flexibility and corrosion resistance. It also doesn’t soften when heated, which makes it easier to process than other thermosetting resins. The thickness of the copper layer is another important factor when selecting a substrate for a flex circuit, as it determines how much flexibility the board will have. Copper-clad laminates (CCL) with varying copper thicknesses are available, but thicker CCLs offer better conductivity and etchability.
Types of Substrates Used in Rigid-Flex PCB Manufacturing
To enhance the reliability of a flex PCB, manufacturers typically coat it with a dielectric coverlay. This layer encapsulates the outer surface of the conductor and prevents it from being damaged by chemicals or humidity. The coverlay is attached to the base substrate using acrylic or epoxy adhesives. These adhesives ensure strong bonding while preserving the flexibility of the circuit.
A protective finish is also necessary to keep the copper traces from oxidizing or becoming exposed to corrosion. This can be achieved through various coatings, such as HASL, ENIG, and OSP. The finish also helps to improve solderability and adherence to the copper, which is essential in making it suitable for use with various kinds of connectors.
When constructing a flex-rigid circuit, it is advisable to use a rigid core and a flexible section separated by stiffeners made of FR-4 fiberglass. Depending on the specific application, the stack-up of a rigid-flex circuit may include up to six copper layers and four rigid sections. The flex sections are typically constructed of two conductive layers from separate FCCL cores and two prepregs.
When it comes to choosing a manufacturer, be sure to select one with ISO 9001, IPC-A-610, and UL certifications. This will show that the manufacturer follows strict quality guidelines and has a comprehensive inspection process, including visual, automated optical inspection, and X-ray inspection. Lastly, it’s important to check the manufacturer’s price-performance ratio. Higher production volumes usually result in lower prices per unit due to economies of scale. It’s also a good idea to ask about the company’s warranty and testing requirements, as these can influence the overall cost of the circuit.
