Flexible PCBs for Mobile Devices

Smartphones have become an essential part of daily life. Inside these devices are a wide variety of components, and flexible printed circuit boards (FPCs) play a critical role in supporting their functionality.

This section explains how to choose the right FPCs for smartphone applications.

What Kind of FPCs Are Best for Smartphones?

Compact Design and High-Density Integration Are Key

There are many types of flexible PCBs used in smartphones, but the key consideration is whether they can support the mounting of complex components and circuits in a limited space. Since smartphone batteries occupy a significant portion of the internal space, the mainboard—which houses many components—must meet strict requirements for space efficiency and high-density layout.

Flexible PCBs that meet these demands include multilayer flexible PCBs and rigid-flex PCBs. While double-sided flexible PCBs can also accommodate components on both sides, they generally offer less design flexibility compared to multilayer or rigid-flex options.

Key Features

Optimized for Smartphone Applications

Multilayer and rigid-flex PCBs are both types of flexible printed circuit boards (FPCs) that are well-suited for use in smartphones.Their ability to accommodate components and circuits across multiple layers enables high-density integration, which is essential in compact device design.

Another major advantage of multilayer and rigid-flex PCBs is their ability to consolidate multiple circuit boards into a single unit. This allows manufacturers to achieve the same level of functionality while saving space—an ideal solution for devices where internal real estate is limited.

In smartphones—where slim, lightweight designs and strict space constraints are the norm—this high-density capability becomes a clear advantage.

On the page linked below, we feature recommended manufacturers that specialize in flexible PCBs optimized for smartphones.If you're currently evaluating FPC suppliers, be sure to check them out.

Reasons These Options Are Recommended

Enabling Smaller Camera Modules Through Higher Density

The flexible PCBs mentioned above are particularly well-suited for smartphone cameras because they simplify wiring and contribute to overall miniaturization of the camera module. For example, if an application requires three single-sided flexible PCBs, sufficient internal space must be reserved for all three. However, with double-sided, multilayer, or rigid-flex PCBs, these can be consolidated into a single board, reducing the space needed while maintaining full functionality.

Reducing the number of boards also decreases the number of connectors required to link them, which in turn minimizes the risk of signal noise. In applications where even minor interference is unacceptable, this noise reduction can offer a significant advantage.

FPC for Smartphones Cost Perception: Where to Increase or Decrease?

FPCs for smartphones require advanced specifications because they need to fit into a limited housing space. Because of this, even a small change in design can result in large cost fluctuations. Specific factors that may cause cost increases or decreases are,Number of Layers," "Materials," "External Processing," and "Yield."These four factors are listed below. Control of these factors is the key to managing costs.

Factors that tend to increase costs (checklist)

Factors that tend to increase the cost of FPCs for smartphones, such asIncrease in number of layers (multilayer)are listed below. More layers increase the cost of materials and the number of processes, leading to higher costs. Also, as for materialsLCP (liquid crystal polymer) and PI for high frequencywill increase the unit cost of materials.

Other,External form accuracy and processing methodThe cost varies depending on the type of product. For example, laser processing is used for low-volume production and complex shapes, and the unit cost is higher for mass production. In contrast, die machining requires a higher initial cost, but the cost per piece is lower.

Thus, there are a variety of factors that can easily increase costs. Please refer to the list below for a summary.

• Increase in number of layers (multilayer)
• Material grade (LCP and other high-frequency materials, etc.)
• Fine wiring/narrow pitch
• External form accuracy and processing method (laser/mold, etc.)
• check request

Specific measures to reduce costs (what can be done in the design phase)

• Reduction of over-specification (materials/number of layers/tolerances)
• Clarification of bending section conditions to prevent rework
• Fixing of prototypes and evaluation items prior to mass production start-up

Specific measures to reduce costs in the design phase include, first of all, the materials to be used, the number of layers, and tolerances.Check for over-specification in some areasIf there are excesses, consider reducing them.

Also, if the conditions of the bending section are left ambiguous, there is a possibility that design changes will occur later on. For example, if changes need to be made just before mass production, this rework will result in significant costs,Clarify conditions and prevent reworkIt is important to Other,Fix prototypes and evaluation items prior to mass production launchto do so also prevents the incurrence of extra costs.

Summary

High-Density FPCs Are Ideal for Compact, High-Performance Cameras

When it comes to miniaturized, high-performance camera modules, flexible printed circuit boards (FPCs) that simplify wiring are a great fit. If you're unsure which type to select, consider starting with double-sided, multilayer, or rigid-flex PCBs to balance space efficiency and performance.