home > blog > Flex Printed Circuit Board Materials and Construction

Flex Printed Circuit Board Materials and Construction

Star level: icon_staricon_staricon_staricon_staricon_star

Fri, Jun 05, 2020

HDI 1.jpg

Are you an electronic manufacturer or a flex printed PCB construction specialist? A PCB professional needs to have an insight into Flex Printed Circuit Board Materials and Construction. The PCB tracing has become increasingly dense due to the improvement of its components, density.  With this improvement of material density in the construction, it has become easy to implement multiple functions. The development builds up exits from one layer, two-layer, and three layers to even more. It increases density and downsizes pitch.

As an electronics manufacturer, you face some different requirements when you are integrating complicated circuits into a complete application. There are undoubtedly some extraordinary requirements for the purpose. It needs to be light weighted and, at the same time, durable to stand in an environment where there are heat, vibrations, and moving parts of machinery. Moreover, the circuit integration should not b expensive with no error-prone assembly by the individuals. It should be repeatable with a high level of IC design.

You need to go for rapid prototyping and implementation, as time is crucial for the process. For all these factors, flex printed circuit boards are beneficial. You can use this board in different fields like medical, aerospace, and consumer electronics.

Design changes

There have been considerable changes concerning size in the last 30 years. You must have seen that mobile phones, laptops, and electronic players have gone through dramatic transformations; you see these devices smaller and smarter than ever before.

Flex printed circuit boards offer you considerable design freedom. In this way, these products may be lightweight and durable. These PCBs differ from rigid PCB

Flex PCB

Flex printed circuit boards are flexible circuits that come with a very thin substrate and extended bendability, tensile strength, and elasticity. You can modify them into complex three-dimensional forms to use in different systems. It includes the aerospace industry, wearable technology, and hearing gadgets. The material used is thinner than average but stilled and etched. In this way, these circuit boards are preferred to rigid PCBs for specific uses. Moreover, you have the benefit of removing traditional wiring harness and ribbon connectors, if you need so.

The following features are part of flex printed circuit boards.

1. You can mold these circuit boards up to 360 degrees.

2. Resist vibrations and disruptions in different environments.

3. Compact, lightweight, and you can reduce the weight.

4. Small and elastic, lesser typical wires

5. Warp able without breakage.


Flex circuit boards are a combination of standard circuit board construction with a flexible look for specific conditions where you need durability. The material and layouts involved in the creation of these circuit boards are versatile.


Materials Used in Flex Circuits

Flex circuit board core material consists of the flexible polymer as compared to standard PCBs that use fiberglass or metal as their base. The substrate in flex PCBs is a polyimide film. It is the feature of PI film that does not soften when heated with thermosetting it becomes flexible. Most of the thermosetting resins become rigid after they are cooked. This feature makes the PI the best choice for PCB construction. Standard PI does not provide enough resistance to humidity and tears if you choose an upgraded PI film; it may address the issue.

A flex PCB needs an adhesive or unique base material for its layers. Previously the adhesives did not provide reliability to PCBs. So now there is adhesiveness PI that may be attached to copper without support. There is no risk of breakage due to the thinner design.

Though there is a variety of material used in flexes printed board construction, there are some main component parts in the structure.

1. Base material: it consists of a flexible polymer film and the base for lamination. The base material is responsible for the basic electrical and physical properties of the circuit.

2. Bonding adhesives: the adhesives are used n bonding the different parts together when you are setting a laminate. It is a crucial element of a laminate.

3. Metal foil: metal foils are conductive elements; the circuit parts are etched on metal foil. Copper is a top choice for this purpose. Copper is known for its immense flexibility. It is also a good conductor.

Each material type is needed to offer consistent performance. It allows PCB to meet the demands.

Space, weight, and costs

If we redesign our products with flex PCBs, it may give immediate benefits for weight. These types of circuit boards come with a 75% weight reduction as compared to other PCB designs. In these PCBs, we use an incredibly thin substrate that is made of polyester or polyamide material. These films can be as small as 12-120 microns thick.

It is a replacement of wiring harness and ribbon connectors that were used to link different circuit boards. In an automobile, we connect the engine control unit to the lighting components or dashboard. It reduces the assembly costs to a considerable extent. It will reduce the number of connections up to 70% if we compare it with traditional wiring. It also reduces the chances of errors.

Usage in the aerospace industry

HUD is used in the aerospace industry with a vivid objective. It displays the operational data to the pilot. The pilots need not look away to have a look at vital operational data during the flight operation. Now a recent extension of HUD offers you 3 D holographic images in a flip-down mounted to a helmet.

The medical industry and flex PCBs

The medical industry also utilizes flex PCB for hearing devices. It provides high resolution than traditional instruments. There are some other applications of printed circuit boards in the pharmaceutical industry.

Bottom line

These circuit boards surely have the upper hand over other types. Their small and flexible size and shape make these circuit boards attractive for use in different industries.

We have gone through Flex Printed Circuit Board Materials and Construction. It is important for anyone related to flex PCB construction, design, marketing, and even consumers to get an insight into different aspects of its build-up.