Wholesale Rigid-Flex PCB: The Ultimate Guide

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Oakley Mae

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You have a wide array of choices when designing a wholesale rigid-flex PCB.

However, few will guarantee you a top-notch product for your application.

Moreover, errors become apparent when you manufacture the rigid-flex in bulk. 

So what steps must one take when making wholesale rigid-flex PCBs?

Well, we have all you need in today’s article. Let’s get started. 

Table of Contents

What’s Wholesale Rigid-Flex PCB?

Before discussing wholesale rigid-flex PCBs, let’s first look at a rigid-flex PCB.

A rigid-flex PCB is a printed circuit board that combines flexible and rigid PCB technologies. 

Consequently, it draws benefits from both PCBs making it more versatile and suitable for certain applications.

On the other hand, wholesale rigid-flex PCBs are printed circuit boards manufactured in high volume to deliver them in large quantities.   

Wholesale Rigid-Flex PCB Assembly

Pick and place machine mounting components onto a PCB

(Pick and place machine mounting components onto a PCB)

The process of making rigid-flex PCBs is more complex since they have parts that are rigid and others flexible.

Moreover, the components attach to the board to form one single structure.

Here are the steps to follow during the assembly of rigid-flex PCBs:

Prepare the Materials

The materials you’ll need to assemble your rigid-flex PCB include flexible films, adhesives, and substrates.

First, clean all the materials to ensure you don’t introduce impurities into your PCB assembly.

Next, cut the copper-clad laminates, a polyimide substrate, stiffeners, and the coverlay.

Create an Inner Core for the Flexible Part

The second step involves creating an inner core for the flex section of your circuit board.

Cover both sides of the polyimide layer with a thin copper foil if the design consists of a single layer. 

Add the Inner Core Circuits

At this stage, you aim to add circuits and connector traces on the foil and remove all extra copper.

To do so, cover the copper foil with a photoresist to be safe if ultraviolet irradiation occurs.

Afterward,an opaque film draws PCB connections on the copper foil.

When you turn on the light, the dry film safeguards the copper traces from damage. 

Next, clean off the uncured photoresist using the right chemical solution and dissolve extra copper using sodium hydroxide.

If done correctly, you should remain with well-defined copper traces. 

Laminate the Polyimide Layers and Create Circuit Traces

Laminate all the polyimide layers in your rigid-flex PCB before creating the circuits.

To do so, electroplate the circuit using copper before using tin.

The reason we electroplate with tin is to protect the copper traces. 

Next, remove the photoresist and any remaining copper from the non-circuit area using a sodium hydroxide solution.

Afterward, remove the tin, drill through holes using a laser drill, and laminate the coverlay. 

But be very careful while drilling, as errors at this point are irreversible. 

Now we are done working on the flex section. 

Laminate the Rigid Section of the Rigid-flex PCB

Rigid printed circuit boards

(Rigid printed circuit boards)

Laminate alternating copper and prepreg layers if your PCB has copper-plated through holes.

Second, create the circuit traces before using a drill to create holes through the circuit board.

Moreover, use a laser drill to create holes through the alternating copper and prepreg layers if it’s a high-density interconnect (HDI) circuit board. 

Remove Excess Prepreg and Finalize the Assembly

Use a laser to remove excess prepreg to allow easier access to the flex section of the board.

Furthermore, apply a solder mask, surface finish, and silkscreen on the surface of your rigid-flex PCB. 

Next, do printed circuit board tests like flying probes and nail-in-bed tests to ascertain the quality of your PCB.

If it passes the test, then your PCB is ready for use.

Advantages of Wholesale Rigid-Flex PCB

An engineer assembles circuit boards by hand

(An engineer assembles circuit boards by hand)

Fewer Materials Makes Them Cheaper

Sometimes, manufacturers use fewer materials to make rigid-flex PCBs than they would with rigid circuit boards.

Consequently, the smaller size of rigid-flex PCBs reduces manufacturing costs significantly.

But that’s not to say that size alone determines the price of a circuit board.

The price decrease results from rigid-flex PCBs having fewer components than rigid PCBs. 

Supports Miniaturization

As technology advances, there’s a need for smaller lightweight devices.

As a result, newer devices are getting smaller yet more powerful than their predecessors.

And manufacturers are opting for rigid-flex PCBs as they support miniaturization

For instance, the rigid parts of the rigid-flex board will serve the purpose of hosting essential components like the processors.

On the other hand, the flexible parts will bend to allow for easier installation. 

Rigid-Flex PCBs Are Reliable

There’s no one-fit-for-all regarding the longevity of your printed circuit board.

However, rigid-flex PCBs last longer than rigid and flexible ones.

The reason is that they don’t have cable connectors which are generally the source of some faults. 

They Are Simpler to Assemble

Rigid-flex PCBs are not only easier to install but also simpler to assemble.

Generally, PCBA assemblers spend a lot of resources ironing out errors before the assembly process. ‘

Such errors can result from poor cable assemblies and affect the working of the whole circuit board.

To avoid errors, rigid-flex PCB manufacturers integrate connectors into the flex section of the board. 

Fewer Tests Than Other Circuit Boards

A flying probe test on a PCB

(A flying probe test on a PCB)

Most PCB manufacturers conduct tests to ensure a printed circuit board works as expected.

Additionally, they subject the PCB to controlled conditions to ensure it won’t fail in the future. 

To give their customers high-quality boards, the manufacturers do PCBA failure analysis before supplying them.

On the other hand, the compact nature of rigid-flex PCBs means that only one test is sufficient. 

Less Prone to Human Errors

Generally, buyers would request a prototype from the manufacturer to assess the quality before purchasing wholesale.

Usually, these prototypes are error-free since working on a single circuit board is easier. 

Where the errors start appearing is in large-scale production.

High-volume rigid PCBs usually have errors that increase the cost of maintenance and repairs. 

On the other hand, rigid-flex PCBs lack connectors reducing human errors during installation.

Additionally, assembling the circuit boards is easier as you don’t have to think about where to connect the cables. 

FAQs

How expensive are rigid-flex PCBs?

Rigid-flex printed circuit boards have different price tags ranging from a dollar to as much as $100 and more.

Interestingly, placing a price tag on printed circuit boards is difficult since the better the board, the higher the value. 

Also, the complexity and materials used in manufacturing go a long way in determining a rigid-flex PCB’s price tag.

Generally, you may find that rigid-flex circuit boards are costlier than rigid and flexible PCBs. 

Where can you apply rigid-flex PCBs?

Rigid-flex PCBs are popular in applications that lack space for installing electrical connectors.

For instance, laptop manufacturers use rigid-flex PCBs as connectors between vital components like the motherboard and screen. 

In effect, the rigid part of the PCB attaches to both components, whereas the flexible section serves as a connector.

Additionally, you can use flex PCBs in applications that don’t support rigid PCBs.

What is the wholesale rigid-flex PCB pricelist?

The price of a single rigid-flex PCB ranges from $0.1 to around $10, depending on your supplier and the complexity of the board.

Consequently, you can calculate the price of your wholesale PCB depending on the number of circuit boards you purchase. 

Moreover, contact your supplier, as different manufacturers have discounts when you purchase wholesale. 

Conclusion

Rigid-flex printed circuit boards are revolutionary in aerospace and medical appliances.

The reason is that they have the benefits of rigid and flexible PCBs.

Additionally, they are less prone to human error during assembly and installation. 

If you plan to manufacture flex PCBs in high volume, we hope they guide you on how to start.

However, remember that the flexible polyimide core shrinks when you etch away the copper.

Always account for this variation when designing your rigid-flex PCB.