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Top Key Considerations While Designing Flex PCB Prototypes!

By | Date posted: | Last updated: September 22, 2021
Flex PCB Prototypes

Flex PCBs are ubiquitous in their use these days. From finding a place in smart watches, mobile phones to industrial application, its usage will only increase, as miniaturization becomes a norm.

The big advantage of flex PCBs is that it can be fitted into space-constrained environments. In addition, they are suited for use in products where there is vibration, constant movement as also mechanical stress.

Additionally, Flex PCBs offer great electric performance. They have a low dielectric constant that allows electrical signal transmission. Their excellent thermal properties make the cooling of components easier, and a higher glass transition temperature ensures that components can operate in elevated temperature conditions.

Despite its advantages, however, designing of Flex PCBs comes with some constraints. For one, the set-up cost of manufacturing flex PCBs is higher. Let us look at some design tips for flex PCB prototypes.

Design tips for Flex PCB Prototypes

  • Due importance needs to be given to component placement. You need to be particularly careful of the spacing when the circuit is being bent. The use of 3D flex PCB design tools can go a long way in ensuring this.
  • In order to prevent vias from cracking, it is important that the vias be tear-dropped. Also, wherever anchors or tabs are added the annular rings need to be large.
  • Due to the flexible nature of the circuit, the pads are susceptible to lifting off the substrate. It, therefore, needs to be anchored. This is done by extending ties from the pad that are encapsulated by the coverlay. Also, large pad sizes work well as they help with stress relief. In fact, pads need to be larger than the drilled hole as the prototype could be subject to bending at different angles.
  • Traces need to be routed perpendicular to the bend line.
  • Mechanical stress needs to be spread evenly on all traces.
  • A large bend radius works much better than sharp angles. Curved traces cause lower stress than angled ones. Also, traces should be kept perpendicular to the overall bend.
  • A hatched polygon for the ground plane works much better than a solid-filled polygon plane. With a hatched polygon, the risk of copper cracking is significantly reduced.
  • The flex layers should be placed in the center of the stack-up. By doing so you tend to offer protection from exposure to outer-layer plating. It also eases manufacturing and improves impedance.
  • The thickness of the material needs to be determined taking into account factors such as size of the bend radius. As a thumb rule, the bend radius of a flex PCB shouldn’t be more than 10 times its thickness.
  • Impedance control is a challenge when it comes to flex circuits. Single-layer flex circuits can use a co-planar stripline construction. Two-layer flex stack-ups will benefit from a microstrip structure that works well for 50-ohm circuits. With higher layer counts you can create a stripline construction.

Some of the pitfalls to avoid at the design stage, when it comes to Flex PCBs include:

  • Considering flex at the end of the assembly as opposed to the beginning results in many issues including creating a more expensive flex.
  • Not taking into account Design for Manufacturability practices into account results in costly errors. Factors such as minimum line width/spacing, annular ring etc. must all have manufacturing allowances built into the CAD design.
  • Not taking into account the different tolerance capacities can have its implications. Very often, designs don’t take into account the realities of the material. Hole pattern locations, for example, can inhibit flexing.
  • Not having the documentation in order also leads to a number of issues. Whether it is not creating a comprehensive drawing package or improper revision control can all have their implications.
  • There are also electrical and mechanical design issues to be considered. Some of these include considering the number of flexes, balancing the electrical and mechanical requirements. For example, high-speed signals require thick substrates. Similarly, high current layers require thicker foil and adhesives.
  • It is also important to take into account the cost drivers such as the number of layers into account. Also, slight adjustments in shape can lead to cost differences, especially for larger circuits.

Taking the above aspects into account can go a long way in ensuring the efficacy of flex circuits.

Mer-Mar Electronics is one of the leading PCB manufacturing companies, providing services from designing to final prototypes. We follow industry’s best practices, ensure standard quality PCB assembly prototype that our clients do not deal with recall or rework. Ask your queries related to flexible PCB prototyping and flexible PCB fabrication services by emailing us at or call us at (760) 244-6149.

How to choose the Right Material for Your next prototype circuit board assembly project?

By | Date posted: | Last updated: August 25, 2021
Prototype Circuit Board Assembly

With the use of PCBs becoming ubiquitous, what is important is the choice of the right material as that is what determines the functionality as well as durability of the PCB.

Let us first look at what are the elements involved in circuit board material.

Circuit Board Material

The circuit board foundation comprises the substrate and the laminate. The substrate is a non-conductive dielectric material. Laminates when used in conjunction with substrates provide the copper foil or surface material.

It is the substrate and laminate that together define the following:

  • Electrical properties
  • Mechanical Properties
  • Thermal properties of the circuit board

Needless to say, that a choice also has to be made of the most accurate board type to meet the bespoke requirements of the project.

Let us look at the various board types in some detail:


Especially when it comes to circuit board assembly prototypes, FR-4 is the most widely used material. In fact, FR-4 is a grade of material as opposed to a single material. Made of woven fiberglass cloth with a flame resistant epoxy resin binder, it is highly popular and versatile. It is known for its mechanical strength and its near zero water absorption. With its insulating qualities, it is widely used in a variety of applications and can work in different environmental conditions. Importantly, FR-4 also works well when it comes to affordability, durability, and performance.

Roger’s material

Rogers as a company is known to manufacture laminate materials for circuit boards. Their laminates are known for cores that have high frequency properties. They are known for their performance as well as electrical properties. Besides, they offer several advantages such as:

  • Low electrical Signal Loss
  • Low Dielectric Loss
  • Better Thermal Management
  • Improved Impedance Control

Little surprise then that Rogers material is used for high-speed designs, RF, Microwave as well as Mobile and high-power situations.

Metal Core

As opposed to the widely used FR-4, metal core PCBs contain a base metal material. The major advantage offered by these PCBs is that the core can redirect heat away from the components. Heat Dissipation is therefore well managed.

Did you know; the metal core PCB is also referred as a thermal PCB, metal backed PCB or MCPCB.

The metal core of the PCB can be:

  • Aluminum Core
  • Copper Core
  • Mixture of Alloys

In case of requirements of high thermal performance, dielectrics are often being used. Metal Core printed circuit boards are also a great solution where cooling of LEDs is a priority. They are therefore increasingly finding application in lighting applications.

HDI material

HDI boards have a high line distribution density. They are extremely helpful as they not only help reduce the weight and size of equipment, they also improve performance. With blind and buried vias and microvias, HDI PCBs is one of the fastest growing technologies. It lends itself to miniaturization of products and in improving their functionality.

High Tg material

Simply put, Tg or Glass Transition Temperature is the maximum temperature at which the substrate remains rigid. High FR4-Tg material therefore has better resistance to heat and moisture. With a greater adoption of RoHS (Restrictions of Hazardous Substance) PCBs, the importance of High Tg material is going up, as the lead-free solder needs higher temperatures. The High Tg PCBs offer improved stability of the device including the heat and moisture resistance.

How to choose the right PCB material for prototype circuit board assemblies?

As there are a wide variety of choices that are available, it is imperative to analyze the exact needs of your project to be able to use the right material.

The standard FR-4, for example, works effectively in most applications and is also affordable. For prototypes, specifically, this is the material of choice.

However, if you are looking for dielectric properties, Rogers Material will prove to be an excellent choice. High Speed Designs, RF, microwave, or mobile applications particularly benefit from Roger’s material.

An electronics project where heat dissipation is of prime importance will benefit from metal core PCBs.

Similarly, high-tech applications, dense packages, smaller and lighter products benefit from HDI material.

Last, but definitely not the least, high power density and heat generation will benefit from High Tg PCBs. These can also operate in relatively elevated temperatures.

The choice of the right material, of course, is the first and the most crucial step in prototype assembly. In that way, the prototype circuit board assembly will particularly go through close monitoring during the assembly process, so as to watch for any errors as also make any course corrections along the way.

We have over 40 years of experience in complete electronics manufacturing services from designing to final prototypes. We help our clients to select the best suitable material. We follow industry best practices, ensure standard quality PCB assembly prototype that our clients do not deal with recall or rework. In case if you have any requirements, get a quick PCB assembly quote, or get in touch with us at or call us at (760) 244-6149.

The Importance of Rapid Prototyping in Aerospace Industry

By | Date posted: | Last updated: April 20, 2021
Aerospace Electronics

Manufacturing sectors including the aerospace industry are prone to many challenges of time, cost, and technology. But in addition to these, the aerospace sector has some more significant regulatory requirements. The aerospace PCBs are expected to be of top-of-the-line performance and unmatched quality. Meeting all these requirements and demands can be challenging. For that reason, what we do is go for rapid prototyping! This offers numerous benefits for the aerospace industry to create new designs and cutting-edge technologies.

Engineers today are rapidly increasing the prototype services in multiple sectors of the economy including the aerospace sector. They design new prototype models and refine their ideas before committing to the final production designs. The rapid prototyping services are highly beneficial for the aerospace or aviation industry.

What is rapid prototyping?

Traditional prototyping has been the norm for years, but things are rapidly changing. Computer-aided designs along with new manufacturing techniques have taken over.

Rapid prototyping is the fast fabrication of any physical component, model, or assembly using computer-aided designs. This is usually done through 3D printing or additive manufacturing. When the rough design matches closely with the proposed finished product then it is said to be a high-fidelity prototype and if there are marked differences between the prototype and end product then it is a low fidelity prototype.

Importance of Rapid Prototyping

PCB manufacturers go for rapid prototyping that can aid in visualization, design & development of the manufacturing process before the final production. It is used for creating parts and models used by a wide range of applications across multiple industries like aerospace and medical device prototypes.

  1. There are numerous benefits of rapid prototyping like one can have a full picture of how products look and behave in the early stages of PCB design and manufacturing. This lets you perform changes or improvements to be implemented early in the process. The time taken for this varies from a few days to months.
  2. One of the main reasons why people go for rapid prototyping is that companies can enjoy greater freedom of design. They can create multiple models of designs, explore many more, without incurring massive costs.
  3. Rapid prototyping for aerospace electronics is a cost-effective way as it is an automated process that requires less manpower. It is one of the inexpensive ways and in fact easier to develop. By acting quickly and solving problems early on, you can reduce the risk of costly errors during the PCB manufacturing stage.
  4. Plus, it is also extremely precise as everything is automated and there is no scope for error. Being able to use computer-aided designs, the amount of material wastage is also reduced and doesn’t require special tools for PCB prototyping.
  5. PCB manufacturers embrace rapid prototyping as they will be able to cut down the time to market. They will be able to build and test the PCBs in small sections. This allows various departments to develop functional designs independently before combining them. This vastly shortens the testing time as well.
  6. Many electrical and mechanical engineers go for rapid prototyping as it makes the process of building geometrically complex parts with ease. This is so true in the case of aerospace systems. They work on multiple prototypes before they design things that fit perfectly.
  7. PCB designers can also confirm the size and shape dimensions before they go ahead with the manufacturing. They can see for themselves if all the components fit in the perfect manner and finish them while the engineers can test the performance and optimize the locations accordingly.
  8. Another benefit of PCB rapid prototyping is that companies can have the flexibility to test out different materials. Traditional prototyping processes limit the materials used for creating models. But with rapid prototyping, companies can enjoy a greater degree of flexibility creating several models out of different materials. This is more desirable for the aerospace industry.
  9. If you are aware that the materials used in aerospace applications are a bit on the high price. Rapid prototyping can provide you the flexibility for testing and evaluating alternatives on the less costly side before investing in tools and committing yourself to molding parts in the production materials.
  10. Rapid prototyping also helps designers to present new concepts to the board members, clients, and investors for easy understanding and approvals. The visualization process helps the designers to receive instant feedback from the stakeholders like customers and clients.
  11. Rapid prototyping is also an iterative process and it allows customer requirements to be incorporated into the designs easily and in a cost-effective manner. This also reduces the need to build customized products to be designed from the ground and at the same time providing greater choice and flexibility for the customers.
  12. Rapid prototyping is also a viable alternative to overseas manufacturing of prototype PCBs. OEMs can gain back control and keep it under their oversight. Many downsides like long turnaround times, different time zones, longer time-to-market, costly minimum order requirements, etc. can be overcome easily. With the same costs, OEMs can now invest in future technologies and stay competitive.

And if you are wondering what all aspects can have rapid prototyping, we would say everything! Rapid prototyping can contribute to nearly all aspects of aerospace design whether they are electronics, interior, and exterior components, or mechanical parts, etc. The aerospace industry can go for rapid prototyping right from the initial design to specialized production parts. This can even span to any repairs down the road.

The purpose of the entire process is to help the companies reduce their costs of designing and creating products by reducing the raw materials. The cost, of course, varies depending on several factors like size or volume of the part, surface finish, materials used, and what post-manufacture process is needed.


Rapid prototyping is a viable means to build next-generation electronic products and solutions to reduce costs and to market quickly. By adopting the latest technologies, we are capable of producing PCBs in lesser turnaround time even when the PCBs have multiple layers and several interconnects. Dense and functional multilayer PCBs can be built in as little as a few hours.

Mer-Mar Electronics is a trusted source for rapid prototyping. We offer extensive services that range from casting to 3D printing, design, functioning, mockups of individual components like control panels. We also offer prototyping services for designing single components with both flex and rigid capabilities. When compared to any overseas contracts, our in-house rapid prototyping is practically risk-free and we respect your intellectual property rights. If you are looking for a prototype or a mockup, you can always contact us.

Best Practices for designing Medical Device Prototypes!

By | Date posted: | Last updated: May 11, 2021
Medical Device Prototypes

If you are developing and manufacturing electronic devices, then don’t make the mistake of ignoring the design aspects of it. Quite often, we see that design for manufacturing (DFM) takes a backseat without any regard for the long-term consequences. Don’t think of cutting down the costs while working on designing the prototypes. It is found that products without design often take a longer lead time and are of lower quality when compared to the products that are designed.

If you are a novice PCB manufacturer and wondering how to get your design prototype for a medical device right, then you are at the right place! Of course, some of the design tips and practices provided in this article are meant for mature designs as well and not limited to medical device prototypes.

Be open to Modifications

Don’t be ambitious and over-confident of getting everything right in the first spin. Things are bound to go down but that’s the only way to abandon that doesn’t work and find the one that works. Ensure all the traces are accessible from the top layer for it is easy to cut, scrape the solder mask, and easy soldering. Make the Vias and test points large enough to easily solder jumpers to these if required. If these are placed too closely, it makes it difficult to modify, and hence some extra space between the components is required while you are designing the layout itself.

Flush out the problems early on

Medical devices are heavily regulated, and you need to be sure of the compatibility issues as you keep adding the components one after another. Even if it’s too early to test the board, you need to give the head start for flushing out the problems at the inception stage itself. Once you have the design prototype, you can look for any issues that rolled out accidentally onto the board. It is better to design in parts rather than populating it with total disregard to the early-stage testing. Remember, it’s the best to nip the issues in the bud itself before they cause chaos later.

Get ready for Multiple Iterations

The design cycle involves heavy consultations with many mechanical engineers and electrical designers. They would be aware of all the constraints of a PCB design. Often, they propose a board outline and your in-house team can hash out the possibilities and rearrange the components, connectors, and placements. You can tweak them, give the final touches, and throw them back to the design team to understand the feasibility issues. This process involves multiple iterations and also relies on accurate 3D modeling of the board, connectors, and wiring.

Ease of PCB Assembly & Serviceability

You may be paying attention to a myriad of trivia, but certain simple things tend to slip out of your mind. Your meticulous routing and placing of components are convenient for everyone? Can a human reach into the assembly and connect them to the cables? Do pads connect to the ground fill ease solderability with thermal relief connections? Can you easily export a 3D model of the board for virtual testing? How about the placement of the components? If you screw up any terminal blocks for connectors it is going to be a nightmare. You need to unscrew every terminal and remove everything for debugging purposes.

PCB Component Placement

Does your contract manufacturer use automated equipment? Do they on conveyors and fixtures for transporting products through the process? Good design practices include spacing between components. They shouldn’t be close to the edge of the circuit board. Also, avoid odd angles. By following them, you can avoid additional paneling thereby, reducing the manufacturing costs as well.

Stay Mindful of PCB Component Sensitivity

It is a known fact that electronic components do come around moisture and may have to face extreme temperatures. So, you need both moisture and temperature-sensitive components while designing and selecting electronics components. You need to be mindful of how components cannot withstand SMT reflow profiles or water wash processes. These elements may demand more labor and higher assembly costs for remaining resilient in these environments. Understand that many variable capacitors, switches, resistors, connectors cannot be simply washed or coated. Only for the water wash process, if the specified components are compatible with this process.

You also have to work with your PCB contract manufacturer during the design phase itself for determining the optimal materials for conformal coating. LEDs, connectors, and switches have a variety of heat tolerances and when you use them on RoHS PCBA, you need to make sure that they are compatible with the temperatures for RoHS processes.

Add lots of Test points

Expect the best but prepare for the worst! You need to think of the potential issues that do not go right. So, you need to add a lot of test points and put a signal trace for easily tracking the issues. This helps in easy tracking and understanding the errors rather than guessing what might have gone wrong. Having as many test points as possible on the board reduces a lot of headaches and hassles making the entire test process easier.

How about Recycling Old Circuit?

If you have any sub-circuit from the previous design that fits your current projects, why don’t you consider saving your resources by reusing that sub-circuit from the previous designs? For instance, you can switch the power supplies from one design to another. Doing everything from scratch is often time-consuming.

Reduce your Component Footprint

Identify only the essential and eliminate the rest. Try to put down the component footprint to a minimal level by getting rid of the unnecessary components. If there are any components that you might think you need but still unsure of their requirement, then it is better to bypass them for the time being. For example, an RC low-pass filter at the analog input is good to have but not at all essential. You can easily leave this out and instead put a zero-ohm resistor in its place.

How about having a ground plane?

It is recommended that you put a ground place on all layers. You can stitch these together with lots of vias. If your board has both analog and digital sub-circuits, it is best to split the ground planes to minimize the noise that passes onto analog circuits.

Conduct a PCB design review

Before transferring your PCB design to production, why don’t you conduct a design review? You can carefully review and optimize several things like layer count, component density, panel designs, and assembly tools. With proper communication with your contract manufacturer during the design and prototyping phase, you can achieve high-quality PCB designs at the lowest cost possible.

The aforementioned tips and suggestions would help increase your chances of designing good quality printed circuit boards. You can take a look at the Mer-Mar Electronics PCB design services to see if they match your specific needs. We provide design services for various industry verticals like military, aerospace, telecommunications, and more not just for medical devices.

Are you looking for PCB manufacturing, PCB Design, PCB prototyping, medical device prototypes, medical device printed circuit boards or any custom circuit board manufacturing?

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