When designing a product for mass production, you need to be well-versed in the design and manufacturing processes involved. When you’ve aced these fields, know what is required, and are well aware of the factors involved, your duty as a designer will be done. Get your rigid-flex PCB manufacturer started on your project by providing them with the necessary manufacturing documents. Fabrication worries and requirements for stiff-flex boards differ slightly from those for rigid-flex PCBs.
In this article, we’ll outline some of the details you should include in your fabrication paperwork to avoid miscommunication during the manufacturing phase.
1. Documenting Your Flex PCB for Manufacturing and Assembly
Documentation preparation is the most vulnerable point in the process since it involves communicating with the fabricator on what should be included in the rigid-flex PCB assembly and where any mistakes or misunderstandings should be addressed.
It might be summed up in a few simple guidelines:
- Verify the fabricator’s capability to construct your rigid-flex PCB
- Get their input on how to best tailor your layer stack to their needs.
- Include them in the process from the beginning.
Due to decreased yield of back drilling and high cost, layer pair planning and documentation for through-hole plating and drilling are essential. Blind vias from a rigid surface layer down to an opposite flex-circuit layer require back drilling.
2. Output Data Set
Speaking with a small number of local rigid-flex PCB capable board houses, you will learn that many designers are still submitting Gerber files. However, when it comes to flex documentation for GenFlex and related CAM systems, ODB++ v8.1 or later is preferred due to the addition of certain layer types to the task matrix.
There are certain problems if you use older versions of ODB++ or Gerber for the output data set. Rigid-flex PCB sections of the layer stack each require their own unique die-cut patterns and route tool paths, which the fabricator must create.
Producing mechanical layer films to demonstrate void placement in stiff sections and, more importantly, covercoat or coverlay placement on exposed flex zones is essential. When considering whether components can be mounted on flex areas, the covercoat or coverlay must also serve as a mask for component pads.
Drilling and plating through-holes requires careful consideration of layer pairs because blind vias from a rigid surface layer down to an opposing flex-layer necessitate return drilling, which increases costs and reduces yield.
The difficulty for a designer then becomes how to define these levels, zones, and stacks.
3. Define the Stack by Area Using a Table
When communicating with your fabricator, the layer stack design is likely the most crucial piece of information you can supply. Rigid-flex PCB also necessitates providing distinct stacks for distinct regions, with the obvious delineation between them. Create a replica of your board’s outline on a mechanical layer, then use that to guide the placement of a layer stack table or diagram, complete with a pattern-fill legend for the areas that will house the various layer stacks.
Fill patterns for stiff and flex regions. You can utilize corresponding fill patterns for distinct stack regions to demonstrate which stackup layers belong to the Flexible part and which to the rigid part.
4. Conveying the PCB Design Intent
This introduces a new challenge in that you’ll need to specify, in 2D, where components and other crucial items can and cannot cross the boundaries between rigid and flexible parts. All of this information must be included in either a fabrication drawing or an assembly drawing.
The fabricator will have a better grasp of your intentions if you provide a 3D model with both flexible and rigid sections. This is commonly done today using MCAD software after the STEP files of the PCB layout have been imported.
Making a diagram in an MCAD program can help find interferences between flexible and rigid components before they’re built. The online Design Rule Checker (DRC) provides a visual representation of interferences and allows users to manipulate the visualization in real-time. Having a 3D animated simulation showing how the rigid-flex PCB board would fold for installation into the product enclosure or assembly is highly desirable for the assembly manager and personnel. When putting together the documentation for an assembly, it might be really useful to have a 3D movie or screen grab made directly in the CAD program.
5. Placement
Rigid-flex PCB architectures suggest components may exist in layers besides the top and bottom. This presents a bit of a challenge in PCB design software, as components are typically only allowed to be placed on the top or bottom of a board. Therefore, the capacity to insert components into lower-level layers is required.
This also suggests that silkscreen may be present on flex layers. Not a problem, as coverlay material can hold fast to silkscreen ink. The trickier part is ensuring that the ink color selected stands out sufficiently against the coverlay. Resolution is also compromised since the ink must travel a tiny distance past the screen before it can settle on the flex coverlay. Talk to the fabricator to find out what’s feasible and affordable.
To clarify, this is a reasonable way to place embedded components onto cutout parts of the board if you are already sketching the regions of the PCB which are exposed flex layers and installing components on those regions.
6. Documentation
You’ll need to provide a series of detailed documentation detailing the cutouts and the layers they affect. This will be constrained by the fabricators’ chosen approach. Options include back-drilling and several laminated stack-ups.
It is crucial to convey your goals and reduce the amount of distinct cutout stack components. Don’t forget to keep cuttings from different sides of the board from ever crossing.
In dynamic applications, it is common practice to use stiffeners or rigid sections in places where components will be installed on flex regardless. This is done so that fatigue from circuit movement around rigid component pins doesn’t lead to dry solder junctions or copper splits.
This isn’t always essential, though, because sometimes the flexible area will be permanently connected to the rest of the board upon installation into a fixed base.
Incorporating an automated drawing utility into your ECAD program makes it easy to create documentation for rigid flex PCBs, such as fabrication and assembly drawings. In your rigid-flex PCB or flex fabrication drawing, you should be sure to include the following details:
- A diagrammatic representation of the structure, down to the smallest detail.
- Tolerances and hole diameters are laid up on a drill table.
- Controlled impedance.
- Specification diagrams for key components with part numbers.
- Documentation of all fabrication
- Complete assembly steps.
Rigid Flex PCB Cost Comparison; What’s the Answer?
In PCB design, knowing the exact cost of your project upfront is essential. Specifically when comparing the costs of regular PCBs versus rigid flex PCBs. In most cases, people are confused as to what to choose for their project. Which is the better option? To get a feel for this, it can be helpful to compare prices from several rigid flex PCB manufacturers. This way, you will get a clear idea which will help you make an instant decision.
Let’s just get this out in the open: it’s going to cost you more to manufacture a rigid flex PCB design than a conventional PCB. When compared to the common practice of fabricating stiff PCBs, the most commonly used – FR4, the production of flexible PCBs is more ad hoc. You might need copper, specialized material, and assembly for rigid-flex PCB printed circuit boards.
The following are some of the ways in which the construction of a flex circuit might vary:
- Thickness and type of foil
- Film construction and thickness as a starting point
- techniques and adhesives for interlayer bonding
- Structural and mechanical backing materials and their attachment
Because of its construction and materials, a flex design will have specific qualities that make it suitable for a given use. However, this distinctiveness might vary from one vendor to the next based on how each vendor constructs the design. For instance, the bond ply utilized by different vendors can vary, which can lead to unexpected results when the product is put through the rigorous conditions of the intended application.
The raw cost of producing a flex design is generally higher for various reasons. You must pay more to ensure you get the particular design you require.
Things to Think About Before Making a Choice
The raw cost of producing rigid flex PCB circuits represents only a fraction of the full price tag. Here are some other factors to think about when estimating the total price of rigid flex circuits:
- A conventional PCB layout may necessitate additional PCB layouts or cable layouts to connect all of the necessary components. The expense of developing these supplementary designs will increase, whereas it is possible that a single rigid-flex PCB design might offer the full answer.
- It is expensive to manufacture and test several PCB designs. You can save time and money by switching to a single rigid-flex PCB design instead of several individual assemblies.
- Comparatively, the rigid-flex PCB design is the connecting cable, whereas connecting printed circuit boards requires additional connectors and cables. It’s a win-win situation where everyone saves money.
Consider the reliability implications of using many PCBs, each with its own set of connections and connectors. Solder and other assembly-related problems will be more likely to occur. As a result, you’ll have to spend more time and money on these.
What is the Difference in Price Between Rigid and Flex PCBs?
The upfront cost of producing a rigid-flex PCB design may be more than that of a conventional layout, but this type of board may end up being less expensive in the long run. Before settling on a final price, it’s crucial to factor in the full cost of expansion, production, and the materials you’ll be working with. If you want to know the true cost, you have to look at the big picture. A circuit board made with rigid-flex PCB design will have different requirements for material and copper than a regular circuit board.
Rigid Flex PCBs and Your Future: Smart, Effective Designing
Using a PCB design computer-aided design (CAD) system that keeps track of the cost of your is a terrific approach to ensure that you haven’t missed anything. Connecting your online bill of materials system with your component suppliers means you can access up-to-the-minute data on the availability, price, and quantity of all the parts you need.
These sophisticated features Hemeixin have been discussing are available in PCB design software. This way, you’ll have access to your design data from both the schematic and the layout views, making it more than just a report generator. It integrates seamlessly with the rest of the Altium Designer unified design platform and keeps you up-to-date on the components you’re using, thanks to a cloud connection with your favorite vendors.
When it comes to PCB design, we are often asked to make a square peg fit into a round hole. Projects are often constrained to the 2D plane of space due to the available equipment or gadgets, even though we are trying to fit thousands of different components onto a board no bigger than a dollar note and maybe even a quarter.
After spending hours perfecting a PCB design, it’s disheartening to discover that it exceeds the device’s space requirements.
A 2D plane does not need to be changed in any way to succeed in creating an extreme PCB with a high density of interconnects. With the help of multilayered vias, you could add more layers to the board. To fit even more parts on our plane, you may be able to test the limits of your edge clearance tolerances. Alternatively, you might look into rigid flex PCB design and its advantages.
What is Rigid Flex for PCBs?
Rigid flex PCB combines the advantages of rigid and flexible PCBs. The PCB’s rigid-core is the familiar-looking board that holds many of the parts. As its name suggests, the flex PCB part can be twisted, rolled, bent, sat on, and even used for fetch.
Amazing engineering goes into making flex PCBs. As the components can be housed on flexible material, they can be used in almost any design. However, it might be challenging to mount them to a device because there is no rigid backbone to rely on. Rigid flex PCB is the next step up, as it allows you to securely affix the rigid part to your device while using the flexible part to increase the area needed to three dimensions.
Five of the Ample Benefits of Rigid Flex PCB Technology
When compared to conventional stiff boards, rigid-flex PCBs provide many advantages. These days, lightweight, portability, and adaptability are all standard features in electronic equipment of all sizes, from simple remote controls to complex radar systems. Rigid-flex PCBs printed circuit boards are playing a significant role in achieving this goal.
The board can be made to fit the device, rather than the other way around when the device is designed around the board’s specs. It is small and light, making the packaging smaller. Moreover, its compact design is a major factor in the miniaturization of products. It’s highly flexible and foldable, making it ideal for compact gadgets.
No connectors, soldering, or crimped contacts go into its construction. This strengthens its robustness and dependability in high-stakes settings. There are fewer interconnects and less chance of circuit failure because it combines stiff and flexible circuitry. Furthermore, the assembly’s high thermal stability is a result of the polyimide utilized in it. This outstanding quality makes it an excellent option for defense and military uses.
The best part is that the assembly process is relatively easy. You only need a few parts. There will be savings in labor and raw materials. It can be installed on the wall or ceiling with minimal effort and holds up well against radiation, oil, and chemical exposures.
Rigid-flex PCBs are made with a wide range of materials and a wide variety of designs to fulfill the needs of clients in a wide range of sectors. The manufacturing process allows for a high level of robustness, making it possible to create a product that can survive harsh environments in the manufacturing setting. These boards are widely used in numerous industries, including aerospace, construction, manufacturing, automotive, power generation, and consumer electronics.
Listed below are five of the many advantages of rigid flex PCB technology:
1. Form to the Device
If you are ingenious, you can now shape your rigid flex PCB around the device in 3D space, freeing you from the confines of the gadget’s inside space. All surfaces are fair game for mounting your boards. Any weirdly shaped gadget can have the design integrated into it so long as a flex material can be run from one stiff board to the next.
2. Light-Weight and Compact
Due to the nature of the design inspiration, the rigid-flex PCB material used to construct this board is naturally considerably lighter in weight and more compact than a standard rigid board, despite its superior performance. You can cut down on bulk and weight by doing this.
3. Designed without Solder Joints
Construction of a stiff flex board involves placing a rigid flex PCB between two or more rigid boards without using any solder connections between them. There are no unnecessary connectors, solder points, or contact crimps with this construction method, which is a huge plus. As its adaptability is tested, this will only strengthen the structure as a whole.
4. Fewer Material Means Lesser Cost
The use of rigid flex PCB material typically results in a reduction of overall material usage, which in turn reduces overall material costs. Your costs will go down, and your procurement team will have less to do as a result.
5. Protection against Exposure
Another advantage of rigid flex PCB material is that it provides lasting defense against potentially damaging exposure to radiation, UV rays, and chemicals. You won’t have to put additional protective layers to protect the project at hand; these boards will do the task perfectly fine without damaging anything.
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