The use case for rigid flex PCB
Jun 20,2019

When to use flex

It’s obtaining tougher to fit every little thing in the box; it’s additionally getting even more pricey. One remedy guaranteeing to aid developers meet the size restraint directly is rigid flex PCB technology, however the majority of design teams try to stay clear of making use of rigid flex PCBs when product expense is a problem. However is it actually as pricey as we believe?

To start with, consider the cost of the standard rigid-cable-rigid PCB assembly to one based upon rigid-flex innovation. The previous construction works well for short-run designs; nonetheless, it needs connectors on each board as well as the interconect, every one of which increase BoM expense Furthermore, the rigid-cable-rigid design is prone to ‘cool joints’, as well as lowered service life. On the other hand, rigid-flex circuits remove these joints, making them far more trustworthy and also able to provide in general greater item top quality as well as durability. So while rigid-flex PCB technology is absolutely not new, various considerations currently make it a lot more sensible– not the least of which is expense.

Mimic the cost.

In some styles, rigid flex will not be a feasible alternative, and also you must do your due diligence in establishing the break-even factor where the prices are about equal. This type of cost simulation can be done by considering the total priced quote prices for fabrication as well as assembly. The PCBs can be quoted before design, as long as the criteria of design are well comprehended (for example, the layer pile, estimated by means of count, track and area proportions, etc.).

We performed a manufacturing expense simulation with an actual rigid flex design and also a relative rigid-cable-rigid equivalent. The component BoMs for comparison differed just in the cable television as well as ports required for the non-flex variation. For our simulation, the standard design is comprised of four-layer boards that utilize flexible wire and ports in between them, while the rigid-flex design is a four-layer PCB with 2 internal flex layers. Manufacturing price for both layouts is based on genuine PCB fabricator quotes, as well as consists of the expense of assembly.

Locate your break-even point

As the job volume shown in Figure 1 strikes 100 units, the rigid-flex design ends up being a more economical option compared to the traditional design approach. A vital reason for this expense financial savings is that rigid-flex circuits do not make use of connectors/cables or require any type of port assembly. Likewise, they showcase boosted integrity and process yields. That’s just the pointer of the iceberg.

Because rigid flex PCBs call for no wire assembly, their general assembly effort is lowered, as is their examination complexity– both which driving a car down expense. Additionally, less parts should be bought, reducing the supply chain risk. Rigid flex PCBs can be developed to make item maintenance easier as well as a result, more cost-efficient during the product lifecycle.

Exactly what about design time?

While the expense of manufacturing, assembly, screening, and logistics are key factors in taking into consideration the practicality of rigid flex PCB innovation for any type of given growth, project and also design costs can not be neglected. Rigid flex PCB design frequently calls for the mechanical group to assist with the flex portion of the design, and also PCB combination with the end product. The procedure is very time consuming and also expensive, in addition to prone to mistakes.

Making matters worse, PCB design tools frequently neglect the suitable as well as folding aspects of rigid flex design. Rigid flex technology design requires developers to assume as well as function in 3D. The flex portions can be folded up, turned as well as rolled to adhere to the design of the system. However traditional PCB design devices do not support 3D board design or the meaning as well as simulation of bends as well as folds up in the flex part of the design. They don’t even sustain the meaning of different layer heaps in different parts of the design, including the locations making up the design’s flex component.

Because of this, rigid-flex developers have been forced to manually equate both the flex as well as inflexible sections of their 3D design right into a flat, 2D representation appropriate for fabrication. They have to manually document all areas of the design that are flex, as well as double check that no vias or elements have actually been positioned near the changes between the design’s flex as well as rigid parts. This procedure is governed by numerous extra rules, the majority of which are, not also surprisingly, not sustained by most PCB design software application.

Generally, the extra effort it has actually required to design rigid flex PCB as compared to common stiff PCBs using conventional PCB design software application has made them a lot less set you back affordable. The good news is, modern design devices with sophisticated 3D abilities, as well as support for the definition and also simulation of bends as well as folds in the flex section of the design, in addition to the definition of different layer heaps in different parts of the design, are currently offered. These tools normally eliminate the have to handle the flex part of the design with mechanical CAD tools, conserving developers and design groups both time and money.

Design in 3D to make sure success

Early control in between the developers and the circuit board producer, sustained by the usage of a modern PCB design tool, is one more aspect making rigid-flex modern technology a more economical choice. Rigid-flex layouts call for closer cooperation between the developer as well as producer compared to conventional stiff board layouts. The tradeoffs required to generate an effective rigid-flex design translate to a collection of design policies the developer could establish with the fabricator’s input. These factors to consider consist of the variety of layers in the design, materials selections, advised dimensions for traces and vias, attachment approaches, and dimensional control. With the right design tool, these factors to consider can be plainly specified and provided the proper weight they are worthy of beforehand to make sure that the rigid flex PCB can be correctly enhanced, even further optimizing its general expense as well.

There’s no refuting that existing market fads as well as consumer demands are pressing designers and design groups to their restrictions, forcing them to seek brand-new choices to the digital design obstacles they now deal with. These difficulties, and also particularly the requirements being placed on today’s mobile phones, are pressing rigid-flex modern technology right into the mainstream, and also making it far more commercially sensible for a range of applications. The accessibility of modern-day PCB design devices that support 3D item development, very early cooperation, and all required rigid flex meanings as well as simulation substantially reduce the pain of rigid flex PCB design and make it a much more compelling solution– one that under the best situations is less expensive compared to rigid-cable-rigid PCB design. For today’s design teams, that selection could merely mean the difference between product success or failure.

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