Amazing New PCB Stiffener is Here to Make Your Life Easier!

PCB Stiffener

Printed Circuit Boards, or PCBs, have been in the electronics industry for quite some time. However, since they hit the market, they completely altered the manufacturing process of many electronic gadgets. Moreover, due to their design, and to some their flexibility (for example, the flex PCBs), technicians utilize them to make compact but powerful gadgets.

However, even though they are efficient, PCBs have a rather complex manufacturing process involving various materials. Some of the components technicians use in the PCB production process include PCB stiffeners. But what exactly is a PCB stiffener? Why is it crucial in the PCB production process? And what are some of its applications?

What exactly is a PCB Stiffener in a Flex PCB?

Flex PCB Stiffener

Stiffeners are not electrical pieces you can find in a printed circuit board. However, these crucial components assume the role of providing mechanical support to the circuit board. Moreover, these components are additional mechanical elements that offer circuit boards mechanical support during the PCB assembly process.

Flexible Printed Circuit Boards tend to have some cons, which include being extremely flexible (more than required) or being rigid in areas that need stiffness. Due to these cons, manufacturers mainly utilize human experience to get around these issues and generate efficient flex PCBs. Moreover, technicians with experience in dealing with such situations utilize stiffeners since they work efficiently.

Application Areas of Stiffeners

Technicians utilize stiffeners when they have to stiffen (harden) a specific section in a flexible circuit board. But, before we move on to the application area of stiffeners, you should note that stiffeners aren’t integral components of a PCB design. However, on application, they prevent a flex PCB from bending on a particular section, helping shield the integrity of solder joints and other parts of the PCB.

Here are several application areas of stiffeners:

  • Retaining and routing arrays – technicians must extend the stiffener material into arrays for technicians to achieve this.
  • Meeting zero Insertion Force or ZIF  connector specs
  • Keeping specific areas of a flex circuit stable and flat
  • Facilitating improved handling of thin, flimsy printed circuit boards
  • Constraining the flexible areas to rigid parts as per the design requirements
  • Supporting printed circuit board connectors and components
  • Mechanically supporting specific sections on a PCB that encompass PTH and/or SMT components

Why do Flexible Printed Circuit Boards Require Stiffeners?

Technicians utilize stiffeners on flexible printed circuit boards when:

  • Electrical components are connected or places on a flexible zone
  • The electrical component that is placed on a flexible area on a flex PCB stresses the flexible material due to its weight.
  • There is a need (as per the design requirements) to generate a rigid and flat surface on a flexible zone for better placement of SMT component pads.
  • Connectors that need multiple insertions require stiffeners to assist in the reduction of stress on the pads.

Flex Circuit Stiffener Material

Choosing the perfect material for your printed circuit board stiffener is essential since it offers many advantages in your application area. However, typically, circuit board stiffeners are generated using the following materials:

  • Rigid polyimide
  • FR4

FR4 is typically a woven (glass-fiber) laminate that is reinforced (impregnated) using epoxy resin. On the other hand, polyimide stiffeners are made using high-temp polymers, which are formed into pretty slim film layers. To attain a thicker stiffener, technicians apply more layers to the stack.

One of the most popular polyimides technicians utilize to make stiffeners is Kapton. Technicians primarily utilize this component when the flexible ends require to be thickened and then inserted into ZIF connectors.

However, in some cases, technicians have to utilize substitute materials to generate stiffeners. Some of the most common substitute materials include:

  • Aluminum
  • Stainless steel

However, one major con of utilizing this component is that they are expensive. Therefore, you might end up going over budget.

Standard Stiffener Thicknesses

Typically, the standard thickness of a stiffener tends to range between 0.002″ and 0.059″. However, the typical thickness of a Kapton-made stiffener tends to range between 0.002″ and 0.010. Moreover, the standard thickness of rigid stiffeners tends to range between 0.008″ and 0.059.”

You should note that the thicker the stiffener, the more mechanical support it will provide to the printed circuit board. However, every PCB design requires a varying stiffener thickness. Therefore, you cannot apply the same thickness to multiple circuit board designs.

However, to generate a thicker stiffener, consider using polyimide. These components tend to produce thicker stiffeners.

How to utilize PCB Stiffeners

FlexIBLE PCB Stiffener

When utilizing a PCB stiffener for PTH (plated Through-Hole) components, you should apply the stiffener on the side that the PTH components are attached. Doing so permits easier access to the solder pads located on the flexible circuit. However, you can also opt to apply the stiffener on either side of the flexible circuit. However, taking this course of action will land the printed circuit board assembly into an ACR (Array Configuration Review). Moreover, you should note that when technicians need an AR (assembly array) for flexible printed circuit designs, it is pretty common for them to utilize FR4 stiffeners throughout the board’s array border. Carrying out this process allows the components to run through an auto assembly like rigid printed circuit board designs. Moreover, doing so eliminates using more tooling plates to complete the process.

Typically, during the production phase, technicians must utilize pressure and heat to efficiently attach stiffeners to circuit boards, a process known as thermal bonding. Additionally, technicians can also attach stiffeners using pressure-sensitive adhesives.

In general, the two common types of stiffener adhesive fall under the following categories:

  • Thermally bonded
  • Pressure sensitive

When choosing any of these two adhesives, technicians have to consider a specific performance requirement, for example:

  • Chemical resistance
  • Thermal exposure
  • Adhesion to other components

Differences between Rigidized and Rigid flex PCB

Typically, rigidized flexible PCBs are flexible printed circuit boards bonded using FR4 stiffeners during assembly to boost the board’s rigidity.

Generally, rigid-flex or rigid-flexible printed circuit boards also go by the name hybrid flexible circuit. That is because they involve both flexible and rigid substrates. Technicians then laminate these two components into one structure which has both flexible and rigid properties.

There are no traces or even pads on the rigid regions of a rigidized flexible printed circuit board. The rigid sections only exist to strengthen the board’s rigidity in a particular area. Generally, in terms of their purpose of flexible printed circuit boards, these rigid sections just offer mechanical support.

However, for rigid-flex circuits, both the flexible and the rigid parts have traces, and technicians connect them using holes. Therefore, the rigid parts in rigid printed circuit boards do not just offer mechanical support; they are also essential for providing electrical connections.

Advantages of Utilizing a PCB Stiffener

Heat Dissipation and Strain Relief via PCB stiffeners

When appropriately utilized, stiffeners help in terms of heat dissipation in a flexible circuit board. Moreover, they are also crucial to strain relief by giving a flexible printed circuit board more resistance. Doing so helps improve the board’s durability and boosts its integrity.

Strengthening Solder Joints

Stiffeners effectively strengthen solder joints which ultimately increases abrasion resistance.

Tips to help you select the Best PCB Stiffener Manufacturing Company

Selecting the perfect manufacturer to handle your stiffener can help boost your circuit board quality, which also affects its price. Therefore, if you are looking to apply stiffeners in the production process of your printed circuit board, then it is essential to thoroughly assess different PCB stiffener manufacturers before you settle on one. But what criteria can you utilize to pick the best manufacturer in the market?

Company Profile Consideration

Before settling on a company, you must first consider its profile in providing diverse and high-quality printed circuit board stiffener services and products. If their profile is top-notch, then consider contacting them for stiffener services.

QMS (Quality Management Systems)

For a company to produce high-quality products, it must have impeccable quality management systems. Therefore, before reaching out to a company, you should check its QMS certifications. Doing so will help you determine whether or not the company has the resources, pedigree, and capacity to handle your stiffener needs.

Technological Flexibility

Another vital aspect that you should significantly consider involves the flexibility and adoption of technological advances by a company if it has the latest, state-of-the-art gadgets and tech that implies that it can deliver high-end and high-quality products.

 Cost

The last option that you should consider is the cost. Note that top manufacturers with a lot of experience in the industry tend to bear in-house sourcing mechanisms, which helps them reduce the cost of producing stiffeners. Therefore, these manufacturers tend to charge less to produce your stiffener. Consequently, it would help if you worked with these top manufacturers instead of working with contractors who outsource their resources. As a result, you will save a lot of money.

Conclusion

Flexible and rigid-flex PCBs are vital components in the electronics industry. However, producing these PCBs poses some issues due to the flexibility factor. But, technicians have found a way to get around this issue using PCB stiffeners. Stiffeners provide impeccable mechanical support to PCB, which is essential to their operation. Moreover, since they exist in different variations, you can select the variation that suits your needs.

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