Your Qualified Rigid-Flex PCB Manufacturer in China

Flexible PCBs are used in many complicated devices. The Rigid-Flex PCB combines a wide range of high-quality features. Let us take a deeper look at what these PCBs offer in terms of specs.

What is it about the rigid-flex PCB that makes it unique? Yes, it is the substance that makes the PCB popular among enthusiasts. Various constructions of rigid-flex boards exist. The materials for these PCBs are-

Substrate

Substrate Materials

The most popular rigid-flex substance is woven fiberglass. A thick layer of epoxy resin coats this fiberglass.

Nevertheless, epoxy-impregnated fiberglass is uncertain. It can not withstand abrupt and sustained shocks.

Polyimide

This material is chosen for its flexibility. It is solid and can withstand shocks and motions.

Polyimide can also withstand heat. This makes it ideal for applications with temperature fluctuations.

Polyester (PET)

PET is favored for its electrical characteristics and flexibility. It resists chemicals and dampness. It may thus be employed in harsh industrial conditions.

Using a suitable substrate ensures desired strength and longevity. It considers elements like temperature resistance and dimension stability while selecting a substrate.

Coatings

Cover Layers

These are manufactured by adhering flexible films together. Cover layers are used in the manufacturing of Rigid-Flex PCBs. It protects the whole assembly.

Second, it allows access to the circuitry. These incorporate more processed circuit pads. The third duty is to enhance the circuitry’s reliability and adaptability.

Cover Coatings

Cover lay is not always utilized. A thin liquid coating is put on the circuitry in this manner. It is acrylated epoxy. Other times it is acrylate polyurethane. The most frequent approach is screen printing. Thermal curing is common.

Conductor Materials

Copper is the most chosen manufacturing material for PCBs. In addition to being a conductor of electricity, it is also very workable. The technique uses two kinds of copper foil.

Among them is electrodeposited copper foil. The second is copper foil rolled. These foils come in a variety of thicknesses and weights.

Adhesives

Adhesives are necessary for a PCB’s operation and longevity. Adhesives secure interconnections between conductivity materials and substrates.

PCB adhesives

Polyimide Adhesives

This adhesive’s temperature resilience makes it ideal for the job. It can withstand 500°C. Its intense heat tolerance makes it suitable for a variety of critical applications.

These include military uses and power generating applications.

Due to high thermal expansion tolerance, they are often utilized in multilayer circuits.

Polyester Adhesives

These adhesives are less expensive than polyimide adhesives. They are ideal for making basic stiff flex circuits.

They also have weak ties. Polyester adhesives are likewise not heat resistant. They have recently been updated. This offers them thermal resistance. The change also promotes adaptability. This makes them safe in multilayer PCB assembly.

Acrylic Adhesives

These adhesives are comparatively superior. They have exceptional thermal stability and can resist both corrosion and chemicals. They are effortless to apply and are relatively cheaper. Combined with their availability, they are popular among manufacturers.

Epoxies

This may be the most widely used adhesive in rigid-flex circuit manufacturing. They can also withstand corrosion and hot and low temperatures.

They are also exceedingly adaptable and bond stable. It has a little bit of polyester in it to make it more flexible.

Insulators

Polyimide films are the most often utilized insulators in Rigid-Flex PCBs. It is used on the base metal layer of flex circuits. Polyimide is also employed in multilayered circuits’ inner layers.

There are various types of Rigid-Flex PCB for you to use. These are some of the types which can help you in your project-

Double-Sided PCB

The double-sided rigid-flex board is a double-sided version of the single-sided flex PCB with a copper conducting layer on either side.  These holes connect the layers. This is a standard flex design recognized for its simplicity. Double-sided rigid-flex PCB Stackups are lightweight and reproducible.

Multi-Layer PCB

Multi-layer flex circuits have more than two copper components. A typical circuit has up to ten conducting layers. PTH holes link multi-layer PCBs, much as double-sided flex circuit boards.

This type of PCB is appropriate for applications that demand high-density connections and tight routing of wires. The PTH mounting technique improves solder joint reliability.

HDI PCB

High density interconnects (HDI) are rigid-flex boards that enable more design processes, layouts, and fabrication options. Each HDI has thick flex circuitry with micro vias.

These aid in the production of compact but powerful PCBs with greater functionality. HDIs are noted for their superior electrical performance, increased IC usage, and enhanced PCB dependability.

HDI Rigid-Flex PCB

Rigid-flex offers a wide range of applications. The following are the possibilities:

Medical field

Rigid-Flex PCBs are employed in medical wearables because of their tiny size. Pacemakers, handheld monitors, imaging equipment, wireless controllers, etc.

Pacemaker PCB

Military Equipment

Rigid-Flex PCBs have long been used in military equipment. This is due to the board’s dependability and tolerance to changing environmental conditions.

Weapon guidance and communication systems are examples. Among other uses, they are utilized in tracking and monitoring.

Aeronautics

Like military equipment, aeronautical devices are subjected to extreme environmental conditions. They are susceptible since airline accidents are invariably tragic.

Telecommunications

The telecommunication sector also uses rigid-flex PCBs. This dependency is due to the boards’ heat resistance.  Applications include routers, servers, satellites, and handhelds.

Auto industry

Small devices benefit from these types of PCBs. Numerous little gadgets are fitted in automobiles. These include music players and LCD screens. PCBs are used in navigation and transmission controls.

Manufacturing/industrial

Many devices are made using Rigid-Flex PCBs. These include industrial air conditioning units and automated systems.  Industrial CCTV surveillance systems also employ PCBs.

Appliances

Many consumer appliances use Rigid-Flex PCBs. These include electric irons, lights, and washers. These PCBs are used in TV remote controls and UV water purifiers.

Most people associate a circuit board with a rigid PCB, often referred to as a PCB. Conductive rails and other features are laid on a non-conductive base to link electrical components.

The non-conductive substrate of a rigid circuit board commonly incorporates glass, which strengthens and rigidifies the board. Circuit boards that are robust and have good heat resistance are ideal for supporting electronic components.

However, although a non-conductive polyimide substrate is used for flexible PCBs, conductive traces are still present on the non-conductive substrate.

Flexible circuits can resist vibration, distribute heat, and fold into numerous forms because of their base’s flexibility. Flexible boards are rapidly being utilized in new and smaller electronic designs because of the structural give they provide.

Flexible PCB

So many benefits come with rigid-flexible PCBs. Among the many examples are the following:

• The flexibility of rigid-flex circuit boards allows for the manufacturing of replacement boards for existing devices. Unlike designing a gadget based on the board’s specs.
• These PCBs are lightweight due to their flexibility.
• The rigid substrate helps the simplicity of these boards. This informs smaller packing.
• They are compact and flexible to fit into tight spaces.
• The absence of solder junctions and connectors increases the reliability of rigid-flex printed circuit boards. No contact crimps either. This function assures the board’s dependability and integrity.
• The panels are assembled using polyimide. They can endure high temperatures because polyimide has exceptional thermal stability.
• Rigid-flex boards can also tolerate various environmental conditions. They are also resistant to severe chemicals and lubricants.
• The panels are designed to allow for component attachment on both sides.

Compact Rigid-Flex PCB

A rigid-flex circuit board is both a convenience and a necessity. For many applications, the rigid-flex PCB manufacturers can fit the board into tighter spaces by employing it because they are so compact.

Installing a PCB would be very difficult, if not impossible, without flexibility. The Rigid-Flex PCB design guidelines are as follows-

Keep the trace width and spacing as large as possible inside the flexible components. Make use of the trace width calculator.

PCB Pads and Vias

Your stiff flex PCB pads should have tie-downs or anchoring spurs. The anchoring spurs prevent the base layer and copper separation during installation. Filleted pads avoid areas of stress and fracture while flexing.

Calculate the Bending Radius

When bending stiff flex PCB, you should be precise with your estimates to prevent damage. Minimum bend radius required.

Bending Area Design

Avoid bending your board at the corners. Copper traces function best when positioned perpendicular to the circuit bending.

Avoid inserting curved traces at rigid right angles and 45-degree corners. This may increase bending stress on copper traces.

A severe board bend might generate cover coat creases.  Reduce the total width of the bend area to improve bend dependability.

Plane

If the design permits it, crosshatch the ground sections. This reduces weight and increases circuit flexibility.

The size of the ground plane holes is governed by the shielding or impedance control needs. Consider the copper balance while mastering the continuous ground planes.

Processing

Dry your PCB (4 hours at 120°C) to remove any humidity collected by the polyimide. Within eight hours of curing, you can begin placing and soldering.

PCB Curing Process

Many different materials and configurations are required to get UL certification for flexible-rigid PCBs.

The UL standards take into account many dangers, including the extent of use, materials utilized, and manufacturing and processing techniques. Extinguishing fires and electrical safety are the primary goals for electrical equipment.

The UL 94 of Rigid-Flex PCB accreditation is designed to safeguard electronic components from fire and electrical hazards. As long as the product is not exposed to too much heat, it will not ignite under the test conditions specified by the UL.

UL-94 V0 PCB

Rigid-Flex PCB is complicated and it takes much time to manufacture. It entails various processes that must be executed precisely. An error in the board’s flexible components may significantly impact the final assembly’s efficiency and durability.

Rigid-flex PCB manufacturing processes are-

Preparation of Base Material

Preparing/cleaning the laminate is the initial stage in board manufacture. The laminate containing a copper layer must be carefully cleaned before using other fabrication.

Circuit Design

Creating circuit designs is the next phase, followed by laminate preparation.

Circuit Design Etching

For best results, both laminate sides are etched simultaneously.

Drilling

Precision holes are made using high-speed drilling equipment. Manufacturers of rigid-flex circuit boards utilize laser drilling to generate tiny holes.

Through-hole plating

After drilling holes to specifications, they are chemically coated with copper. This creates electrical connections between layers.

Coverlay or Covercoat

Protects the circuit from severe weather, chemicals, and solvents.

Cutting the Flex

Hydraulic punching is often used to mass-produce Rigid-Flex PCBs.

Electrical Testing and Verification

The boards are tested electrically. Testing ensures the boards are working properly.

Testing Rigid-Flex PCB ensures that the PCB is working properly. There are different methods available To test a PCB. Some of the industry Standard PCB testings are as follows-

Tests for Isolation

To do this, you must check that the requisite resistance exists between two different electrical connections.

Tests for Continuity

This is the process of ensuring that there are no open circuits between two electrical circuits.

Nail Bed Test

When testing a PCB with a bespoke array of spring-loaded pins, a fixture is needed to keep the PCB in place. Test spots on the board trace are pre-determined by the design team so that they may concurrently test many places on the board.

Flying Probe Test

Robotic probes attach to certain nets on the panel and conduct tests on them. There is no need for a bespoke fixture other than something to keep the board in place. Programming the probes for particular spots on the board is required.

Flying Probe Test

Before deciding on a conformal coating removal process, you must first determine the utilized coating. There are numerous methods to identify the coating if you can not acquire the information from the original supplier that applied it.

Conformal Coating Removal

Once you have determined what kind of coating we are dealing with, the next step is to determine how to get it off. Keep in mind that certain methods of removing conformal coatings are more successful than others.

Acrylic

• Chemical Solvent
• Grinding Process
• Micro-blasting,

Urethane

• Micro-Blasting
• Thermal Method

Epoxy

• Scraping Method
• Grinding

Thermal

• Micro-Blasting
• Silicone
• Grinder and Scraper

Designers are encouraged to create workable layouts for Rigid-Flex PCBs using the most appropriate tools. The rigid-flex boards are likely to be inefficient if the layouts are defective.

There are various ECAD programs that you can use in the rigid-flex design. You can efficiently create the board with the help of these programs.

They will also assist you in improving the designs. You will be able to customize the look of your boards this way.

As a result, ECAD software provides a high-quality board in the lowest possible time. The 3D option in this program is critical for creating bends and other delicate components with confidence.

Additionally, ECAD software may change the diameter of traces. For both stiff and flexible features, this is accomplished flexibly.

An effective design is guaranteed by any rigid-flex design program that has these characteristics.

PCB Design Software

Repaired PCB

A stiff flex PCB is typically seven times more costly than a comparable rigid PCB owing to raw materials and poorer overall yields, so they are more expensive.

It is possible to further reduce the cost of the PCB by adapting materials such that layers, thicknesses, and total prices are reduced to the minimum.  PCB design cost will be influenced by several factors, including

Maintaining a minimal number of overall layers.

Making your design more straightforward means that you will have to use fewer prepreg layers to bind your board together.

Minimize the number of layers that may be bent

Rigid laminates are less expensive, whereas flexible laminates are more costly. The board’s total cost may be reduced by reducing the number of flexible circuit layers. Your total package cost is reduced by reducing the number of flexible circuitry layers on your design.

Put a rigid board at the end of all of the flexible arms

Flex cable terminations are often desired by rigid flex designers, often for mating to the ZIF connector or other device. Hardboard is not desired in these areas since it is too thick and inflexible to work with

Now that the rigid-flex PCB is finished, it is time to add components. The steps below explain how stiff flex PCBs are assembled.

Stenciling using Solder Paste

It involves applying solder paste to the board. A thin stencil covers the Rigid-Flex PCB.

Stainless steel stencil required. This allows you to solder paste the PCB’s designated portions. These are the pieces that will hold the components.

Pick and Place

A pick and place device is used after successfully applying solder paste to the rigid-flex board.  Using robotic equipment, surface components are mounted onto the PCB.

Machines are favored because of their dependability and precision. This replaces the old hand choosing and putting method. The machines are also faster and never get tired.

SMT Pick And Place Machine

Quality Assurance

It should be tested once the surface mount elements are soldered to the PCB. During reflow, the rigid-flex board might slide, causing connection concerns. This may cause electrical shorts.

Component Insertion

Many rigid-flex PCBs have parts that are not SMD. These are PTH plated components. This helps send messages throughout the board. This prevents solder paste application.

Final Examination and Testing

To test the board’s functioning. The PCB is placed through simulations that mirror its intended function. The rigid-flex board carries power and simulated signals.

Rigid-flex PCBs may not always have benefits. Some of the drawbacks of these PCBs include:

• These PCBs are made using two distinct substrates. Rigid and flexible substrates are examples of this. This adds complexity and length to the manufacturing.
• The manufacturing procedure for printed circuit boards is more involved than for other circuit boards. Adequate and appropriate software is needed for this. Because of this, it increases the cost of manufacturing.
• These PCBs also need a lot of materials and labor. This is due to the PCB’s sensitivity and the inherent variances in rigid and flexible substrates.

Designers often have to define quantities for a few distinct factors in order to determine impedance:

• The desired impedance
• Trace the height
• Width of the trace
• The layer or layers of the impedance trace
• Traces with regulated spacing between copper components.

PCB Control Impedance

Here are some things to look for in a Rigid-Flex PCB manufacturer.

Industry Knowledge and Skills

Choose a manufacturer that offers the PCBs you need. Not all PCB makers are equal.

Certifications / Quality Assurance

When selecting a PCB manufacturer, consider quality.

Delivered on Time

In many circumstances, on-time delivery is a quality. To be safe, choose a PCB business that has a proven track record of quoting and delivering on schedule.

Cost

PCB cost is determined by various variables.

Source

Foreign supplies are usually cheaper but have additional considerations. Lead times, shipping expenses, customs, and communication issues.

A domestic supplier may be more costly, but you may benefit from shorter lead times, lower shipping costs, and the option to visit the supplier.

PCB Technology

PCB technology is an important price indicator.

Rigid-Flex PCB Manufacturer

Rigid-Flex PCB is a widespread kind of printed circuit board. They have to put in the time and effort to make things correctly. Rigid-Flex PCB assembly and testing need extensive training and expertise.

Since 2008, PCBMay has been producing high-quality Rigid-Flex PCBs in China. All of our PCBs are made to the highest quality standards. You may call us at any moment if you need a quotation or any other assistance.