Looking for a dependable guide to knowing the price of a flexible circuit?
Cost estimation is very critical in PCBs, especially for flexible printed circuits. This in-depth article will be helpful for you to get expert knowledge about this issue. Let’s start.
Flexible Printed Circuits
Flexible circuits are particular types of PCB that are bendable and stretchable to a certain degree. These PCBs, consisting of flexible materials like Polyimide, FR4, etc, have different features and applications than regular circuit boards.
You can implement flex circuits in computer products, gaming consoles, robotics, and medical equipment where flexibility is mandatory.
Are Flexible Circuits more Expensive than other Circuit Boards
Processing of flexible circuits is quite different from rigid PCB manufacturing. Flexible printed circuits offer a certain bendability and stretchability that make these PCBs unique from other circuit boards.
Flex Circuit Manufacturing Challenges
So, manufacturers need to achieve that perfection while processing flex PCBs. But it requires time and experts to bring the desired bendability. That’s why the production cost increases.
Flexible PCBs are composed of particular materials that can deliver flexibility with certain robustness in electronic applications. These materials have specific dielectric properties and thermal stability. That’s why flex PCB materials are comp[aratively more expensive than other PCB materials.
Flexible PCB Materials have a Significant Impact on Cost
Besides, these materials demand a distinct quality not available in general PCB materials. So, manufacturers must manage these ingredients from a reputable and dependable source. This is another reason for the high material costs of flex circuit boards.
Flex circuit designs have more complications than rigid applications. To handle that constraint, manufacturers require experienced and expert engineers and technicians. Besides, the inspections of flex circuits are more in numbers and duration.
Flexible PCBs with Complicated Designs
You need to conduct functional tests, along with thermal tests and flexibility tests. That’s why the overall cost gets high to a certain degree.
Distinct Dielectric Property
As flexible circuits are formed with different conductive layers and adhesives, PCB makers must keep their dielectric constants controlled and almost similar. Otherwise, it can hamper the dissipation factor and impedance matching.
So, the lead time for flex circuits is comparatively higher than that of a rigid PCB, and this feature is responsible for the high expense of these PCBs.
Additional Thermal Management
FPCs are not highly robust to handle extreme thermal shocks. So, manufacturers need to place more PCB vias in different places to handle the thermal dissipation and stresses. But it also hampers the yield, which is closely related to manufacturing cost.
Flex PCB Thermal Dissipation
Factors that Impact the Price of A Flexible Circuit
Price of Flex PCB Materials
When the price of flexible PCB is concerned, you can’t overlook the impact of flex circuit materials. Arguably, FPC (Flexible Printed Circuits) materials cover almost 30-40% of the entire manufacturing cost. So, how can you ignore such a crucial factor in this case?
Flex circuit board materials consist of base materials, adhesives, stiffeners, conductive layers, substrates, etc. In the case of base material selection, manufacturers have options like Polyimides, FR4, Polyamides, etc.
You never get these PCB materials at the exact cost. Usually, FR4 is a less expensive FPC material compared to Polyimides and Polyamides. Besides, this 4th-grade flame retardant material brings a certain robustness to the flex circuit boards.
On the other hand, Polyimide flex circuits initially cost high. But if you consider the positive features Polyimides add to your flexible devices, you can’t reject these materials only for the high price.
Low-cost Flex Circuit
That means you need to choose a suitable PCB material for your flex circuits concerning its cost-efficiency and performance. It is best to rely on a worthwhile manufacturer to handle material sourcing and cost performances.
Flexible PCB Size
Flexible circuit cost and size have a complicated relationship. You can’t relate these two factors by a linear equation. It changes due to the use of board size, assembly process, etc. Mainly, FPC costing varies depending on the following factors-
- Circuit density on a PCB Panel
- How do you assemble the circuits in a panel
Do you have enough idea about PCB panelization?
Don’t worry. We are here to give you the gist of how penalization impacts PCB costing.
Panelization means a process of manufacturing smaller portions (Panels) of the entire circuit board and further connecting these portions like a single array. Most of the circuit boards, irrespective of whether flexible or rigid, consist of rectangular panels.
Usually, flex PCB manufacturers prefer 12” X 24” or 18” X 24” panel boards for standard flex circuits. But flexible printed circuits allow the PCB makers to customize the panel size depending on the design.
Now, come to the point. Manufacturers intend to accommodate as many PCB components as in a single panel to minimize the cost. It happens because the variation of labor cost does not vary in a huge number depending on the materials per panel.
Sometimes, makers choose to interconnect two individual parts placed at a 180-degree orientation. This phenomenon is known as “reverse nesting” in the PCB world, which is effective for cost optimization during PCB manufacturing.
Flexible PCB Panelization
You must nest flex PCB parts in a panel while maintaining the guidelines and concerning the design rules. Here, the point of the assembly process comes.
You must keep a particular gap between two adjacent circuits of a PCB panel. This rule differs from the idea of nesting circuits as many as possible. Besides, you must face problems placing components on the PCB surface in an automated way.
That means you need to consider how you assemble the panel connectors, how to fold the panels, and how you can connect the stiffeners. The manufacturing cost will increase if you can’t solve these issues correctly.
So, it is necessary to make a delicate balance between the circuit density in a panel and the assembly of the panels on the circuit board surface. It is difficult, but the production cost for flexible PCBs relies on this balance to a large extent.
Flexible PCB with Dimensional Stability
This is a cost related to the technical aspects of flexible PCB manufacturing. The engineering costs mainly include-
- Equipment setup cost
- Film processing cost
- Cost of making the Gerber file
- Cost of presenting engineering questions (EQ)
Usually, these costs vary concerning the manufacturers and their capability of delivering flex circuits. Here, the equipment setup cost becomes variable regarding manual and automated testing. Typically electrical tests with automated pieces of equipment charge high.
Flex Circuit having a Low Engineering Cost
On the contrary, manual inspection processing costs are low, but it takes a lot of time, ultimately impacting the lead time and the overall price of a flexible PCB.
Designing a flex circuit plays a vital role in optimizing the cost. Usually, complicated designs are challenging to handle and deserve huge time with experienced designers. The design specification includes the aspect ratio, gap between panels, component placement, tracing, PCB via placement, etc.
If you have proper knowledge of these issues, you can tell the designer to deliver the Gerber file maintaining your requirements. Otherwise, you can propose your demands and wait for the designer to check its feasibility.
If your design consists of regular specifications, it will cost low. But the design cost increases as complexity increases, and the designer needs to run DRC (Design Rule Checking) multiple times.
Flex PCB Volume
This is another vital issue that is highly thought-provoking for PCB makers. Usually, low-volume flexible PCBs cost low. It occurs because these PCBs have a curtailed engineering cost, with significantly low overhead costs. Besides, the lead time becomes short due to minimizing the volume of flex circuit boards.
High-Volume Flexible Circuit
But this narrative has a dilemma. Whether you are dealing with low or high-volume flex PCBs, you must bear the minimum cost for testing, drilling, designing, etc. These costs are not very little at all. You can optimize costs when you run a mass production of flexible printed circuits.
Flex PCB Assembly Charge
The assembly charge for flexible circuits includes the cost of component sourcing as assembly processing. Flex PCBs demand special care during assembly as these materials are less robust than rigid PCB materials.
Nowadays, many PCB assemblers and manufacturers deliver assembly services at variable costs. You must choose a suitable PCB maker concerning your flexible PCB requirements.
Number of Layers
The conductive copper layer is a pivotal part of flex PCB circuit boards. How many conductive layers you are using to construct the flex circuit significantly impacts the production cost.
A single-layer FPC is almost 1.5 times less expensive than a double-layer FPC having the same size. The higher layer count increases the processing steps in flexible PCB manufacturing.
Flex Circuit with High Layer Count
That means the yield probability decreases with the increase of FPC conductive layers. Besides, it lengthens the lead time in most cases. That’s why the number of copper layers is a crucial factor, not less than PCB materials.
Rate of Flex Circuit Yield
FPC yield refers to the perfection rate you can achieve in manufacturing. A high rate of yield is equivalent to high charges. Sometimes, PCB makers need to compromise on this issue to handle the budget constraints.
You must simultaneously focus on some crucial factors to manage the yield rate and cost performance. Such as
- Surface coating
- Number of conductive copper layers
- Number of PCB vias
- Placement of buried and blind vias
- Specifications of PCB vias
Manufacturing or lead time is the estimated period to deliver the product to the clients after completing the manufacturing. This is a significant factor creating so much pressure on the PCB makers.
Usually, delivery time is correlated to the specifications, engineers’ availability, equipment management, and material sourcing. If a manufacturer or PCB assembler can’t deliver the flexible PCB in due time, the production cost must increase, which won’t be profitable from the maker’s perspective.
That’s why lead time maintenance is a mandatory thing in flexible PCB production.
Flexible circuits with heavy copper thickness cost high. That’s why manufacturers intend to incorporate thin copper surfaces into the FPCs. But it doesn’t work well in all cases. Because the copper thickness is related to many electrical properties like current conduction, impedance, loss tangent, etc.
Thick Rigid-Flex Circuit
There is an exciting aspect of impedance control that is often ignored. It is evident that the dielectric constant is a critical factor where impedance matching is required. But you must consider the dielectric stack-up while maintaining the dielectric constant.
Usually, you can find dielectric films with adhesives having different dielectric constants in a dielectric stack-up. As the DK value varies, you must pay more time to match their impedances. This will affect the production cost in the long run.
It is easier to handle impedance in flexible circuits consisting of adhesive-less polyimides because you only need to match the dielectric properties of films. So, this is a vital cost factor when discussing flexible PCB prices.
As complicated molds are a little bit expensive, it is recommended to keep the mold designs plain and simple as much as possible. Usually, flex PCB molds come in two different types. These are steel and knife molds.
Both of these have different accuracy and usability. That’s why you must choose sincerely between these mold shapes.
|Factor||Steel Mould||Knife Mould|
|Usability||1000-50000 times||100-3000 times|
These expenses differ for PCB makers. Usually, operating costs include the location, number of workers, facility, etc.
Except for these factors mentioned above, flexible PCB prices can be altered due to the order quantity, the effect of location on delivery, etc. So, it may seem a hectic job to quote for a flex circuit board remembering all these staffs. But this is a part of your job, whether you are a maker or client.
How Can You Minimize Flex Circuit Cost?
The following guidelines help you control the flex circuit cost-
- Use a reliable cost estimator to get a rough idea about the production cost.
- Keep the number of flexible and overall layers as minimum as possible.
- Use flex PCBs having thin coppers (around 1-6 oz).
- Keep the requirements for matched impedance under control.
- Try to buy many flex circuits and manufacture high-volume PCBs.
- Keep the operating expenses like location, delivery cycle, etc minimum.
Flex PCB Cost Estimator
A cost estimator is a reliable weapon for designers to battle handling design requirements and saving costs. Usually, a flex PCB cost estimator has the following aspects-
- Layer count
- Panel or single circuit board
- Minimum spacing
- Number of vias
- PCB via size
- Surface finish
- Hard Gold finger or Immersion Gold finger
- Copper thickness
So, you might understand that price of a flexible circuit depends on various factors. You have to make your decisions concerning all possible factors so that you can optimize the costs. Contact MV Flex Circuit to get flexible PCB manufacturing service at a decent cost.