{"id":3636,"date":"2023-10-18T09:06:09","date_gmt":"2023-10-18T01:06:09","guid":{"rendered":"https:\/\/www.jingpengpcb.com\/?p=3636"},"modified":"2026-10-02T19:31:38","modified_gmt":"2026-10-02T11:31:38","slug":"manufacturing-of-double-sided-fpc-soft-board","status":"publish","type":"post","link":"https:\/\/www.jingpengpcb.com\/en\/blog\/manufacturing-of-double-sided-fpc-soft-board\/","title":{"rendered":"A Detailed Explanation of the Manufacturing and Connection Technologies for Double-Sided FPCs"},"content":{"rendered":"

As electronic products continue to evolve, an increasing number of applications require flexible circuit boards, also known as \u201cflex boards\u201d or FPCs. In this article, Shenzhen-based FPC manufacturer Jingpeng Electronics will provide a detailed explanation of the manufacturing and connection technologies for double-sided flexible circuit boards, as well as why they are so important in modern electronic products.<\/p>\n

\"Manufacturing<\/p>\n

Overview of Flexible Boards<\/h2>\n

A flexible printed circuit (FPC) is a flexible insulating substrate typically made of polyimide or polyester film. Compared to traditional rigid PCBs, FPCs offer unique advantages, such as the ability to be freely bent, coiled, and folded. This flexibility has expanded the range of applications for FPCs in electronic products, making them particularly suitable for fields requiring high density, miniaturization, and high reliability, such as aerospace, military, mobile communications, laptops, and digital cameras.<\/p>\n

Demand for Double-Sided FPC Flexible Circuits<\/h2>\n

In some cases, the conductor density of a single-layer FPC cannot meet design requirements, or it may be necessary to implement crossed conductor connections. In such cases, a double-sided flexible circuit board is required, which features two layers of conductors bonded to a flexible substrate. The connection between these two layers of conductors is typically achieved using electroplated through-holes, solder-filled holes, or other methods.<\/p>\n

Electroplated Through-Hole Connections<\/h2>\n

Electroplated through-holes are the most common method for connecting dual-layer conductors. This process begins with the formation of through-holes in a flexible substrate, which can be achieved through mechanical drilling or laser drilling. Next, plasma etching or chemical etching techniques are used to complete the preparation of the through-holes, followed by cleaning and roughening of the hole walls, and finally, metallization of the hole surfaces. This metallization can be achieved using methods such as electroless copper plating, conductive carbon film, or black shadow processes. Through the electroplating process, the thickness of the copper can be increased to the required level, thereby establishing a connection between the two conductor layers.<\/p>\n

High-Density Design<\/h2>\n

As the demand for high-density circuits in electronic products continues to grow, electroplated through-holes can be categorized into two types: full plating and selective plating. Selective plating reduces the thickness of the surface copper layer, increases production capacity for fine lines, and reduces internal stress, thereby improving the reliability of the copper foil. Some plating techniques are applied only to the through-hole area, while the surrounding areas are covered with a masking material to ensure a connection between the two conductor layers without compromising the performance of fine lines or the reliability of dynamic applications.<\/p>\n

Other Connection Technologies<\/h2>\n

In addition to electroplated through-hole technology, there are other interlayer connection technologies, such as overlay, conductive material-filled, and polymer thick-film-filled methods. The choice of an appropriate technology depends on the requirements for precision and electrical conductivity. As long as the conductive layers can be interconnected, various methods can be explored; however, the electroplated through-hole technology remains the most common choice due to its widespread use and maturity.<\/p>\n

Double-sided flexible circuits play a critical role in the modern electronics industry, enabling high-density circuits and flexible designs. By using connection technologies such as plated-through holes, reliable connections between the two layers of conductors can be achieved. Whether in PCB manufacturing, PCB design, or PCBA assembly, double-sided flexible circuits are an indispensable component.<\/p>\n

Frequently Asked Questions<\/h2>\n

Q1: What is a flexible printed circuit (FPC)?<\/h3>\n

A flexible printed circuit (FPC) is a flexible insulating substrate typically made of polyimide or polyester film. It can be freely bent, coiled, and folded, making it suitable for high-density, compact, and highly reliable electronic products.<\/p>\n

Q2: Why are double-sided flexible circuits needed?<\/h3>\n

Double-sided flexible circuits are typically used in circuit designs that require higher trace density or trace cross-connections.<\/p>\n

Q3: How do electroplated through-holes work?<\/h3>\n

Electroplated through-holes are created by forming through-holes in a flexible substrate and then metallizing them, thereby establishing a reliable connection between two layers of conductors.<\/p>\n

Q4: What other interlayer connection technologies are there?<\/h3>\n

In addition to electroplated through-holes, there are other interlayer connection technologies, such as plating-over-via, conductive material-filled via, and polymer thick-film-filled via.<\/p>","protected":false},"excerpt":{"rendered":"

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