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Manufacturing Process of Single Sided and Double Sided Flexible Printed Circuit

Updated: Oct 17

Flexible printed circuit is famous for its lightweight, flexibility, and high reliability, which make it an indispensable part of modern electronic products. Especially in high-density and high-performance applications, FPCB is indispensable. Single sided and double sided FPCB are the two main types of FPCB, and each type has a different manufacturing process. Flex Plus, the flexible printed circuit board manufacturer, will take you to understand their differences.

 

What are the Single Sided and Double Sided Flexible Printed Circuit?

Flexible printed circuit can be divided into single-sided, double-sided, multi-layer according to the number of circuit layers, and the production process of different wire layers is also different, taking single-sided and double-sided flexible printed circuit board for example.


manufacturing process of single sided Flex PCB
Single sided Flex PCB

Single-sided flexible printed circuit

Most single-sided flexible circuits are typically manufactured by bonding copper foil to a layer of polyimide dielectric film. This bonding process typically uses a layer of adhesive to ensure a strong bond between the copper foil and the polyimide. Another manufacturing method is to bond the copper directly to the dielectric without the use of an adhesive, and this composite material is called an adhesiveless substrate.

The formation of copper circuit is achieved through photolithography imaging, development, and etching. One method is to pre-punch holes in the polyimide material. The pre-punched polyimide material is laminated to the substrate on which the copper circuit has been formed to form a covering layer to protect the circuit. Another method is to use optical imaging technology to accurately cover the solder mask layer in specific areas of the circuit to protect the circuit and prevent short circuits during soldering (the solder mask layer, as a selective dielectric, only covers the parts that need protection and does not affect other parts of the circuit).

Double sided Flex PCB
Double sided Flex PCB

Double-sided flex printed circuit

Double-sided flexible printed circuit is a type of FPCB that has conductive copper layers on both sides of a flexible dielectric substrate. Double-sided circuits begin with two copper layers separated by an insulating film. Similar to single-sided designs, the bonding between the substrate film and the copper conductors can use adhesive or be adhesiveless. 

 

Manufacturing Process of Single Sided and Double Sided Flexible Printed Circuit


Single sided flexible circuit board is the simplest form of FPCB, characterized by a circuit pattern on only one side of the substrate. The manufacturing process includes the following steps:

Material cutting → CNC drilling → Dry film laminate → alignment → exposure → developing → etching → decoating → surface treatment → pasting covering film → pressing → curing → surface treatment → immersion nickel gold → printing characters → shearing → electrical measurement → punching → final inspection → packaging → shipping

 

Double sided FPCB has circuits on both sides of the substrate, allowing for more complex designs and greater functionality. The manufacturing process for double sided circuit is more intricate than single sided circuit, involving the following steps:

Material cutting → CNC drilling → PTH → copper plating → pretreatment  → Dry film laminate → aligning → exposure → developing → graphic plating → decoating → pretreatment → Dry film laminate → alignment exposure → developing → etching → decoating → surface treatment → pasting covering film → pressing → curing → immersion nickel gold→ printing characters → shearing → electrometering → punching → final inspection → packaging → shipping

 

The Flex PCB material usage and cost of single-sided and double-sided are different. Double sided circuit requires more materials and involves more complex manufacturing steps, resulting in higher costs. Flexible printed circuit board manufacturer Flex Plus provides more cost-effective solutions by optimizing their manufacturing processes.


Flex Plus is a flexible printed circuit board manufacturer that focuses on various FPCBs and provides customized solutions to meet the needs of different customers. The Flex PCB products produced by Flex Plus are widely used in medical and health, new energy vehicles, communication products, precision modules for mobile phones, industrial control, Bluetooth hearing aids and other technological fields. And Flex Plus has established good cooperative relationships with many well-known customers in North America, Europe, Japan, Southeast Asia, and mainland China.

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