Flexible Circuit PCB Assembly

It can be tricky to figure out what you need to know about flexible circuits assembly, especially since it’s not something many people are familiar with or have experience with. Flexible electronic assembly is one of the most innovative and useful circuit boards in the electronics world since it allows you to make low-profile electronic devices with multiple electronic components.
The Circuit board has different types, including a standard or rigid PCB, a flex PCB, and a flex-rigid PCB. Besides, these circuit boards are further divided into single-layer PCBs, double-layer PCBs, and multilayer PCBs.
A flexible circuit board has a flexible base, but the components are just like a rigid circuit board. However, you can turn a flex PCB into any shape while using it which means it is easy to bend.The following article will help you learn everything you need to know about flexible smt assembly so that you can get started working on your designs right away.
Before we move to the assembly of a flex PCB, we want to discuss its applications.

FPCB Applications

The FPCB is a vital part of electronic products that we use daily, such as desktop printers, hard disks, and several other devices. You would see the use of a flex circuit board in the below industries.

• Medical industry
• Consumer electronics
• Communications industry
• Military
• Automotive industry
• Aerospace industry
• Transportation

Engineers use it in the transportation industry because flex PCBs are vibration-resistant and constant movement for several hours can’t damage them.

Choosing The Right Material And Processes

When it comes to choosing the right materials and processes for your flexible circuit board assembly, there are a few things you need to keep in mind.
First, consider the environment in which the board will be used. Will it be exposed to harsh chemicals or extreme temperatures?
Second, think about the amount of flexibility you need. The more flexible the circuit, the more expensive it will be. Finally, consider the size and weight of the finished product.

What Are The Uses Of The Flex PCBs?

Every kind of circuit board has specific uses because it is an important part of different products, especially electronics. Designers preferflexible circuit boards for computers, mobile phones, and servers to make them more effective, less heavy, and more flexible. Though different devices have different shapes, functions, and sizes, they all include flexible circuit boards.
Let’s look at the main uses of flexible Printed Circuit Board
1-FPCB is Flexible

• The flex circuit board is an elastic board that helps in placing it near folds or edges.
• It is suitable for 3-axis connections due to its elasticity.
• FPCB involves minimum wiring, whereas some applications don’t require any wiring at all. So, there are no wiring issues that make a device more reliable.

2-Flex PCB Reduces Weight and Space
Unlike rigid circuit boards, a flex PCB needs less space. According to engineers, it can save 60 percent of space, hence, its weight also decreases.
3-Flex PCB Reduces Connectors
If you use a flex PCB in a 3D design, it will eliminate or reduce connectors. Whereas the bending cycles go up to 200 000.
4-FPCB Eliminates Vibration
A flex PCB is very light which helps it absorb movements or vibrations. So, the vibrations can’t damage an FPCB. Moreover, the solder joints also stay safe.
5-Compatible With Tough Environments
You can use a flex circuit board in tougher environments due to its material. Its main materials are water-resistant, shock-resistant, heat-resistant, as well as corrosion, and oil-proof.
6-Thin layers
Flex PCB has thin layers on the inside which reduce its weight. The copper layers in an FPCB are heavy which if combined with thin layers becomes useful for high-power applications.

Types of Flex Circuit Board

A flex PC Board has different types, including single-sided, double-sided, multilayer flex, and rigid-flex circuit boards. Let’s look at their pros one by one.
Single-sided F PCB: It is economical, flexible, and has many bending cycles.
Double-sided F PCB: Its design is more flexible than others. Moreover, it saves space and provides dual-sided soldering.
Multilayer F PCB: It is lightweight and compact and its flexibility is more in a 3D design. It is compatible with blind and buried vias.
Rigid-flex circuit board: It helps have a long-lasting 3D application having stable parts, pins, heat streaks, etc. It reduces noise and enhances signal integrity.Besides, it is more reliable and offers better impedance.
It helps have minimum mechanical space and reduces the weight of the device. It is compatible with the HDI micro-via. It is economical and offers a flexible pcb design.
Some More Advantages
A flex PCB can give you many benefits, but mainly it enhances flexibility and saves space. Its assembly involves a few items that reduce its cost and manufacturing time.

• A flex circuit board offers a high-heat dissipation.
• It enhances the inner airflow.
• It reduces the size and weight of the package.
• It involves minimum assembly errors.
• It reduces the inductance of wires.
• A flex circuit board enhances the product’s looks.
• The assembly time and cost of the FPCB are less in some cases.

Flexible Printed Circuit Board Assembly

The assembly of a flex PCB is the same as a rigid board except for a few changes due to certain technical needs. The assembly of a single-layer flex PCB consists of the following steps

• BOM
• Electrical testing
• Punching process
• FPCB baking process
• Optical inspection
• FQC process
• Silkscreen printing process
• Reflow soldering
• Packaging process
• Mounting process
• Deep inspection

Flex To Rigid Surface
Since flex PCB is soft and gets deformed, it is hard to assemble it directly on SMT. So, engineers fix it on a hard surface such as a tray for the assembly process. The tray or a hard carrier should be well-intact to make assembly smooth.
Low-Density Assembly
Flex PCBs aremore costly than the rigid circuit board, so most of them are used for connecting different modules having different functions. So, the FPCB assembly involves fewer components in the case of low-density assembly. The quantity of the components ranges from 2 to 50 in this case.
Increased Panels
Manufacturers use many planes during FPCB assembly to enhance the process. A flexible circuit board is used in smart products, such as digital cameras and mobile phones, so a single board is too small. As it involves a few components, manufacturers use panels which are then removed through punching.
Use of Auxiliary Fixtures
Flexible PCB assembly involves auxiliary fixtures as it deforms easily. These fixtures include:

• Baking fixture
• Carrying tray for FPCB
• Electrical and function test fixtures
• Cutting Fixtures

High Demand for Quality
The devices with FPCB are used in an environment where the accuracy of control has to be high. So, the board components should be well-positioned to get compatible with a particular environment.One must focus on certain factors, such as anti-static precautions, cleanliness, and reliable soldering. It also involves several technical issues.
Increased Assembly Cost
A flex circuit board has a costly assembly compared to a rigid circuit board. It involves many fixtures which also increases its cost.Theassembly process takes more time than a rigid PCB. Moreover, the assembly involves lots of accessories and working labor because less equipment is used. Besides, the increased demand for high quality and flawless manufacturing environment also is the reason for the high cost.
However, as the flex circuit board’s application is increasing, so new technology and assembly methods emerge. Eventually, the assembly cost decreases due to less time and tools involved.
Choosing A Supplier
When it comes to choosing a supplier for your flexible circuits PCB assembly, there are a few things you need to take into account. First, you need to make sure that the supplier is reputable and has a good track record.
Second, you need to make sure that they have the necessary experience and expertise.
Third, you should ensure that they are able to meet your specific needs and requirements.
Fourth, you should see if they are able to provide you with a competitive price. Finally, you need to ensure that they can produce high-quality products at an efficient rate.
For example, some of the key considerations when selecting a supplier are quality control measures in place and their ability to adapt to changes in demand. To put this another way, if a company’s success relies on being able to keep up with production rates, it will be easier for them to fulfill orders if they’re accustomed to adjusting according to supply and demand than if they’re not. The same thing goes for quality control, as companies without established procedures may not be as adept at preventing defective products from reaching customers.

Final Words

Flexible circuits are used in a variety of products, from hearing aids to sports-related items like fitness trackers and smartwatches. They allow you to connect electronics into your home, and even onto your body, giving you easy access to valuable data and features. However, with all this flexibility comes the need for greater care in assembly than typical PCBs require. The designer must know about flexible circuits and PCB assembly to ensure the end product works correctly and lasts as long as possible.
Would like to know more about Flexible Circuit assembly or pcb assembly services? Email us at sales@pnconline.com

Written by Sam Sangani

Sam Sangani is the President & CEO of PNC Inc., a Nutley, NJ based Printed Circuit Board manufacturer. Sam graduated from L. D. Engineering College with a BS Degree in Mechanical Engineering. He also continued his education and graduated from Steven’s Institute of Technology where he acquired a Master’s degree in Computer Science.

After completion of his BS, Sam worked as a QC Manager, for Xerox, Romania and London. He was responsible for the Quality Control of Cable and Wire Harness imports from Romania. After completing his Master’s Degree, he worked as a Senior Programmer with IBM, Tucson, Arizona. Sam was responsible for leading the Mainframe System Programming Team.

In 1997, Sam acquired PNC INC., a Nutley, NJ based PC Board fabrication Shop. From 1997-2013, Sam has made tremendous improvements and changes within PNC INC., as he added many new Products and Technologies in PNC’s portfolio. With his proven track record and leadership, PNC has never had an unprofitable year and has continued its growth yearly since 1997.

His current responsibilities are Strategic Planning, Corporate Management, New Business Ventures, Sales & Marketing, Trade Shows, Professional Services and leading productive teams to achieve peak potential. He has also utilized Lean Management techniques which have built a foundation for PNC’s high-paced growth. Sam also enjoys real-estate investing, web design & SEO, trading stocks, options, futures and Forex markets.