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4 layers hdi rigid flex pcb Pros and Cons (flex Hdi pcb guide 2020)


Flexible and 4 layers hdi rigid flex pcb circuit boards

Today, the use of flexible and 4 layers hdi rigid flex pcb in electronic products is no surprise. They are used everywhere. Subsequently, these include:

4 layers hdi rigid flex pcb

  • Consumer
  • consumer electronics
  • mobile phones
  • miniature computers, cameras, etc.,
  • professional electronics for special purposes
  • automobile and aircraft construction
  • satellite and navigation systems
  • military-industrial complex

The advantage of 4 layers hdi rigid flex pcb technologies is not only a reduction in the final weight. Similarly, it allows different parts of the products to move relative to each other during operation. There is no protective solder mask on the entire microwave board.

What is flex hdi pcb?

A flexible printed circuit board is a board that uses a thin, flexible dielectric as its base material. The main base material in the manufacture of PPG is a polyimide film. In addition, these boards can bend, bend and compact.

The main difference between flexible printed circuit boards and rigid ones is the ability to mount in three-dimensional space.

A type of flexible printed circuit boards has a thin insulating base up to several meters long. The thickness of the CHP can be between 0.06 mm and 0.3 mm. Flexible printed cables are usually made with one or two layers of printed conductors.

What is rigid flex pcb?

Rigid-flex printed circuit boards are the most complex interconnecting structures in electronic equipment. Moreover, a simple GZPP has one rigid and one flexible dielectric layer in its structure. These boards can contain dozens of layers of flexible and rigid cores. Moreover, they are assembled into one structure in almost any order.

The use of 4 layers hdi rigid flex pcb allows in a number of cases:

  • reduce the size and weight of the device;
  • embed electronics into a complex shape;
  • abandon the connectors;
  • improve the reliability of connections;
  • simplify installation;
  • provide dynamic flexibility of connections;
  • Simplify maintenance during operation.

Application area:

  • automotive technology
  • Medical equipment
  • sophisticated household appliances
  • onboard electronics
  • military products

Characteristics of 4 layers hdi rigid flex pcb

Flexible and 4 layers hdi rigid flex pcb – a whole independent direction in the production and operation of printed circuit boards. Such boards are often only single. And double-layer and are used both in static applications.

4 layers hdi rigid flex pcb suppliers

Rigid-flex boards combine the technology of conventional multilayer boards with flexible technologies. Such boards are a hybrid design containing both rigid and flexible bases. These are fastened together in a single assembly.

Hdi flexible-rigid printed circuit boards advantages

4 layers hdi rigid flex pcb have both a number of obvious advantages over conventional rigid PCBs and some disadvantages. Hence, the advantages, first of all, include:


  • a reduction in the size and
  • weight of manufactured devices
  • an increase in the reliability of connections due to the rejection of connectors
  • and the provision of dynamic flexibility of finished products

The basic elements of any flexible and flex-rigid printed circuit board are:

Flexible foil-clad dielectric consists of a thin polyimide film with copper. Moreover, it can come with or without an adhesive layer. Adhesives – commonly used to bond layers and attach reinforcement to the edges of flexible stubs in the connector area.

Similarly, covering films are two-layer constructions consisting of a flexible polyimide layer. On which a layer of adhesive is applied. Furthermore, cover films protect the surface of the 4 layers hdi rigid flex pcb from external influences.

Bonding films are three-layer structures consisting of a flexible polyimide layer. On which an adhesive layer is applied on both sides. Therefore, bonding films are used to form a multi-layer flexible structure.

Hardeners and specialized prepregs. The latter are needed to prevent resin flowing from the rigid part onto the surface of the flexible part during pressing.

The choice of materials used depends to a large extent on how. And where the board will be assembled and operated.

4 layers hdi rigid flex pcb design specifications

4 layers hdi rigid flex pcb during the design phase are not much different from rigid circuit boards. Except that the designer must consider the mechanical complexity associated with flexible circuits. For example, a flexible PCB can break if bent during installation.

Therefore, it is very important to create a mechanical model of the PCB. And test it for correct fit before embarking on an electrical design. Ina ddition, it will also allow you to check the ergonomics of the installation. Moreover, it also allows developers to understand the different types of agile schemas and how they work.

4 layers hdi rigid flex pcb Layers

By the number of layers, printed circuit boards are divided into singlesided, double-sided and multilayer.

Single and double pcbs comes with a dielectric base. On top of which a conductive material is pressed – from one or both sides, respectively. Most often it is highly purified electrolytic copper foil. As a rule, fiberglass is used as a dielectric base, less often electrical paper impregnated with bakelite or epoxy resin.

After mechanical and chemical processing a pattern of printed circuit board conductors is formed. Same process goes with 4 layers hdi flex pcb. This drawing is often referred to as a topological drawing. The electrical connection of the layers of the topological pattern is carried out by metalizing the holes.

Multilayer printed circuit boards consist of alternating “thin” layers of dielectric and conductive topological pattern. During the production process, all layers are pressed into one whole – a multi-layer base.

Note: Depending on the design features of the board, electrical connections in a multilayer structure can be made either through vias.

Classification of the pcb layers

4 layers hdi rigid flex pcb company

  • Outer layers. In complex boards, these layers are called assembly layers and are often used only for installing components. In simple boards, in most cases, the outer layers play not only the role of mounting, but also signal (conductive) layers.
  • Signal layers. These are the layers that bear the brunt of creating electrical circuits between electronic components.
  • Power layers.These layers are made with solid polygons (or “mesh”) with minimal ohmic resistance. In addition to providing power to the circuit, these layers act as electrical “shields” between the signal layers.
  • Heat dissipating layers.Excess heat from circuit components is removed and distributed over the entire plane of the board during product operation.


The design of flexible and 4 layers hdi rigid flex pcb is not much different from that of conventional rigid printed circuit boards. The main difference is in the materials used. Therefore, that makes it possible to reliably connect the dielectric and conductive layers. Another feature is the use of specialized equipment and technological modes of manufacturing boards of this type.