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How To Plan Stackup For Rigid Flex PCB

The world is changing at an ever-increasing pace. From smartphones and cloud data centers to medical devices, artificial intelligence, and self-driving cars and trucks. To keep up with electronics industry-wide changes, we need rigid flex PCBs Stackup to smoother the running of equipment.

A rigid flex prototype services provide a better performance, and production process, and enhance results in electronics manufacturing. It is one of the many innovations in the electronics industry that can be used to build the next generation of devices.

A little time spend on reading this post is much worth it for you, if you want to know more about rigid flex PCB Stackup in detail.

What Is Rigid Flex PCB Stackup?

A rigid flex PCB Stackup is a type of PCB that has both rigid and flexible layers. It is an PCB assembly of three or more layers of rigid and flexible materials that are bonded together.

The rigid substrate is used for providing mechanical strength to the circuit board. While, the flexible circuit substrates attached help in the prevention of heat, vibration, and even moisture.

Choosing the best Stackup type for your project requires prior knowledge of its features. Below are the features of rigid-flex PCB.

FEATURES Of Rigid Flex PCBs Stackup

rigid-flex-pcb-design

There are some essential features of rigid flex PCB Stackup are given below:

· Fewer Solder Joints And Connectors

Rigid flex Stack up has the feature of fewer solder joints and connectors than conventional printed circuit boards. It means that it reduces the risk of soldering mistakes, which can lead to costly rework on flex PCB portion or even circuit failure.

· Minimum Board Thickness

These rigid flexible boards technology apply a thin film to achieve an effective board thickness reduction without compromising on quality or reliability. The thickness of this board ranges from 0.2mm to 0.4mm, which makes it more durable.

· High Thermal Strength

Rigid flex PCBs allow for better heat dissipation and increased reliability than a typical rigid board environment. With high thermal strength, you don’t have to worry about over-mating your rigid flex PCB.

· High Aspect Ratio

A high aspect ratio is one where the width is greater than the height. It allows for more space between each component on a circuit board, which can help with signal transmission. In addition, a high aspect ratio not only allows for more space between the tracks but also allows for easier routing of wires and other components.

· Solder Masking

Solder masking is a thin layer of solder where the component position has been defined. It prevents the component from being damaged by abrasion, as well as protects it from electrostatic discharge. The protection is achieved by painting the board with an ink-receptive coating that adheres to the PCB.

Purpose Of Rigid Flex PCB Stackup

Flex rigid board fabrication is a lot more versatile than normally printed circuit boards. They are fast and allow you to use less space as well, which is really important for the development of new products.

By combining all the flexible components in circuit boards, less of special connection connectors are needed. Rigid flex stack advanced construction efficiency and decreases total weight.

Rigid flex printed circuit board’s superior formulation helps to reduce the space and weight issues that we face in conventional PCB.

Uses Of Rigid Flex PCBs Stackup By Industry

You can easily mold flexed curve into your desired shape. A rigid flex stack advanced leads to faster speeds which makes them ideal for a variety of applications. Its simple modular interfaces promote some of the most notable rigid flex PCB usage are associated as:

  1. Consumer Appliances: Washing systems, Solar energy systems, and Ovens.
  2. Telecommunications: Routers and servers, Wireless Communications, and Communications satellites.
  3. Medical Equipment: Drug delivery systems, Imaging equipment, and Pacemakers.
  4. Automotive: Navigation systems, Control systems, and Air conditioners.
  5. Industrial: Automation systems, Test equipment, and Surveillance systems.
  6. Aerospace: Communications, Sensors, and Control systems.
  7. Military: Communications, Tracking System, and Guidance systems

Why Rigid Flex PCB Stackup Matter?

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Not only does rigid flex design give a 3D freedom of flexible circuit boards which is the standard norm now, but they have other benefits like decreased maintenance and a more uniform electrical profile. Rigid flex printed circuit board also promotes optimized housing solutions.

It also includes reducing stress in the critical flex portions of the board and improving thermal uniformity with copper ratio tweaking. Some other benefits of rigid flex circuit boards Stackup are as follows:

· Better Durability And Flexibility

Flexibility and durability are key components of a PCB Stackup. The flexibility of the PCB Stackup is also determined by the number of multiple layers and the type of materials used in the PCB.

The goal of the Rigid flex Stack up PCB is to reduce strain on the PCB that may cause damage to the board. Rigid flex PCB also has excellent mechanical properties, good dielectric performance, and a wide operating temperature range that makes it more durable.

· Saves Space

Space saving is one of the most important factors in rigid flex designs. Save on space and reduce production costs with rigid Flex Stack up.

Its thin, and wide surface area allows for complex circuitry to be implemented without sacrificing the flex circuit efficiency. You can add all the flexible circuit components you need in just one layout.

· Features Single Point Connection

It allows a robust connection between the electronics and supporting structure, as well as a more reliable product.

Single point connection also simplifies rigid flex board fabrication and troubleshooting, while decreasing EMC issues caused by cables that touch each other. It needs less time spent on design and testing. Also, it can reduce the chance of error in production due to a smaller number of connections required.

· Lightweight

Lightweight refers to the weight reduction capabilities or weight without affecting the object’s structure or performance.

The rigid flex Stack up is lightweight and the key to the light weightiness of rigid flex PCBs is the use of low-density flexible substrates. This type of PCB you can use in the industry where the light weight of the product is a key factor for success.

· Perfect For Vibratory And Shockey Environment

Rigid flexible circuit board has a superior formulation that helps for high rigidity, high mechanical strength, and excellent thermal characteristics.

It allows for a better distribution of stress and less strain on the flex PCBs. It will help to protect the devices from sudden impact, vibration, or shocks that could damage the IC devices, which can lead to higher reliability.

Which Type Of Material Used In Making Rigid Flex PCB Stackup?

Rigid flex boards consist of such flexible board substrates that are as follows:

· Copper Foil

Copper a common conductive trace layer found on most rigid flex boards. You can place it to form traces that connect the power and ground planes or runs within the circuit layers. It also provides flexibility with thinner copper foil that you can use for small layer routing, resulting in less waste product.

· FR4

FR4 is also a material that you can use in PCB assembly that provides mechanical strength. It’s composition of fiberglass cloth and a flame retardant epoxy resin binder, which makes it non-conductive.

· Prepreg

Rigid flex PCBs often use prepreg for insulation. It is some kind of dielectric material that goes between two layers, usually a copper foil and a core. You can also refer to it as a binding material. You can use it to bind two cores or a core and copper foil.

· Adhesive

Option exist to use two types of PCB glue, depending on the type of circuit you want to join. RTV super glue that doesn’t emit an acid during the curing process. Cyanoacrylate glue is also useful where you need instant gluing.

Types Of Rigid Flex PCB Stackup

A Typical 4 Layer PCB Stack Up
A Typical 4 Layer PCB Stack Up
  1. Single Layer

In this design, one conductive copper layer attached between two polyimide layers with insulating properties. It also support lean body definition. One of the layers in a capacitor has covered on one side or laminated between two insulating layers.

  • Double Layer

Double layer PCB Stackup is a rigid flex assembly technique that uses two copper conductive layers, with an insulating middle layer, and an external layer of insulation. The outer layers can have covered or exposed pads.

Plated through-holes you can use for making layer-to-layer connections for electricity. Pins, stiffeners, and connectors you can use for a variety of applications. Flex rigid board technologies assure that the electrical performance will exceed than of conventional PCB.

  • Multilayer: Rigid Flex

A Multilayer PCB is a type of rigid flex PCB Stackup that has more than two layers with alternating patterns of conductive material. Multilayer PCB designs are much more complex than double-sided ones.

Any number from 4 to 64 layers is possible. Multilayer PCBs have a coating and glued. So, that you can place layers of heat protection insulation between them. Exposed insulation surfaces also exist on the front and back of each layer.

Electrical connections exist between layers. You can do this with such methods as plating through holes and embedding buried vias for a finished look. It uses stiffeners, components, connectors, heat sink, pins, and mounting brackets.

Conclusion

The main goal of this article is to make you aware of some key aspects of PCB Stackup, you may have not thought of them before. Ultimately, the rigid flex PCB Stackup is a preferable option to the other printed circuit boards out there.

Rigid flex PCB production capability built on core concepts like efficiency, accuracy, and reliability. These allow you to produce the most complex multilayer PCBs in a cost-effective way. We hope all information presented above will be helpful for you in future projects!