How to Improve Reliability & Flexibility in an 8 Layer Stackup Flex PCB?

When designing a flex PCB stackup, you may face some restrictions in enhancing the reliability of the board. Today, we will discuss the ways to improve the reliability of a board by increasing the flexibility and improving design considerations of a multilayer PCB stackup. These steps can be implemented for PCB stackup designs as seen in 8 layer flex PCBs.

flexible circuits

flexible circuits

Improve Flexibility by Reducing Overall Thickness

All or some of the below mentioned steps can be executed to lower the overall thickness of the PCB. A thinner PCB stackup will allow it to be more flexible.

1.Reduce the base copper weight.

2.Reduce the adhesive thickness.

3.Reduce the dielectric material thickness.

4.Using adhesiveless base materials can reduce the thickness of the substrate by 1-2 mils, which is almost 25-50μm.

5.Make use of selective plating to avoid copper plating the conductors.

Improve Reliability by Reinforcing the PCB

Here, the boards, components, and the layout should be designed to deliver a robust structure that can withstand flexing.

1.The weight on both sides of the PCB should be equal. This includes the weight of the conductors and the material.

2.The conductors on different layers of a PCB should not be placed on top of each other. Instead, they should be placed in a staggered pattern.

3.Conductor thickness should always be constant in and near the bend areas.

4.There should be no plated-through holes in the bend areas.

5.There should be no discontinuities near the bend.

6.Traditional copper can be proved to reduce the flexibility of a PCB. Opt for screened-on coatings like silver epoxy.

7.For slits in the circuit, reliefs or tear stops need to be built into the PCB.

flexible pcb

flexible pcb

Tight tolerances will have to be put in place to ensure that your stacked up PCB can provide flexibility as well as reliability. Several of the above-mentioned steps can easily be incorporated in the designing process itself. Your PCB manufacturer should be able to help you with the most appropriate improvements for your application.

Do You Know the Materials Used for Constructing 6 Layer Rigid-Flex PCB?

A six layer Rigid-Flex PCBs, as the name implies, is manufactured using six conductive copper layers. However, do you know the materials used for constructing 6 layer rigid-flex PCB? Now let me lift the veil for you.

6 layers rigid flex pcb

6 layers rigid flex pcb

Base Materials – The most commonly used base materials for manufacturing 6 layer rigid-flex PCB is woven fiberglass impregnated with epoxy resin. The use of cured epoxy makes the board more rigid. Manufacturers also prefer Polyimide rather than normal epoxy resin to ensure extreme reliability in complicated applications. Polyimide is chosen due to their extreme flexibility, toughness, and heat resistance properties. Polyester (PET) is also another material of choice for the PCB fabrication. Manufacturers often choose the most suitable materials according to the specific application requirements of customers.

Films – Manufacturers prefer PET films for producing 6 layers rigid-flex PCB due to their corrosion and heat resistance properties. The thickness of PET films used for the PCB manufacturing vary from 1/3 mil to 3 mils.

Conductors – Copper is the most preferred conductor of choice for making 6 layer rigid-flex PCB and various types of copper are used according to the specific application requirements. Annealed copper is used when repeated creasing or movement of the flex circuit is demanded.

6 layers rigid flex PCB

6 layers rigid flex PCB

Adhesives – The use of high quality adhesive is crucial to make a fine bonding between the conductor and films. Acrylic or epoxy based adhesives are the most commonly used adhesives to achieve a firm bonding, while silicones, hot-melt glues, and epoxy resins can also be used for bonding.

Manufacturers who are very familiar with the properties of the aforementioned materials can conduct their mechanical design, evaluation and testing of the PCBs better. Therefore, a manufacturer who fabricates 6 layers rigid-flex PCB for the automobile industry must quite know the moisture, chemical, shock & vibration resistance properties of the materials used in the construction. This contributes to enhancing the durability of PCBs in the case of industrial specific applications.

Rigid vs Flexible PCBs: Which One is the Best for Your Next Project?

Speaking of “PCB”, many people will think of a rigid PCB. However, the term “PCB” can refer to either a rigid PCB or a flexible PCB. Flexible PCBs are more commonly known as flex circuits(flex boards, flexible circuit boards, flexible printed circuit boards and flexible electronics). Recently, Flex circuits are highly welcome in the market since they can be bent or twisted. However, in the most basic sense, rigid PCBs and flexible PCBs have the same ultimate function of connecting various electrical and mechanical components together.

When to Use Rigid and When to Use Flexible

Rigid PCBs typically cost less than flex circuits as flex circuits may eliminate the need for components such as connectors, wire harnesses, and other circuit boards. By removing these components from a design, material cost, labor and assembly cost are all reduced.

flexible pcb

flexible pcb

Many electronic devices (laptop and desktop computers, audio keyboards, solid-state drives, flat-screen TVs and monitors, children’s toys, and various electronic gadgets) employ rigid PCBs instead of flexible PCBs. However, flex circuits may be found in ultra-compact and/or high-performance devices, including GPS units, tablet PCs, smart phones, cameras, and wearables. Flex circuit makes installation get much easier.

Finally, a flex circuit and a rigid circuit can be used together—as a rigid flex PCB(Rigid flex circuit)—if necessary. The proper application of rigid flex circuit offers optimum solutions for difficult, limited space conditions.

Rigid flex pcb

Rigid flex pcb

Should you have any other queries about flexible pcb, rigid pcb, rigid flex pcb, feel free to contact us. Our sales representative will reply you at our earliest convenience.

What Materials Are at the Forefront of Wearable Technology?

If you were to go to your doctor’s office today for a routine physical, the first five minutes would involve getting your blood pressure taken, taking your pulse, and getting your temperature. In the future, wearable technology may allow you to upload all of this crucial data to your doctor instantly from the devices and sensors already woven into your clothing or even tattooed on your body.

Wearable technology is evolving at a breakneck speed, with the help of advances in flexible printed circuit boards. One of the biggest challenges researchers and manufacturers face when devising wearable technology is creating materials that can flex and stretch while also maintaining conductivity and connections with the different circuits.

FPC in the wearable

FPC in the wearable

Developing just the right materials is a crucial piece in the future of wearable technology.

What Materials Work Best with Wearable Technology?

Wearable technology is a big category and includes everything from patches that can be layered onto skin to coats, shirts, and even sports bras. Each iteration of wearable technology offers unique challenges when finding the right materials.

Graphene

Graphene is a popular material choice, because it is an excellent conductor of electricity and also very flexible. Graphene offers an important alternative to wearables that rely on rigid components that can’t flex well. Researchers are actively experimenting with ways to blend graphene-based inks into cotton cloth.

Thermoplastics

Another option is the thermoplastic polyurethane, a highly adaptable plastic material. Already, a German company is using polyurethane to develop wearable skin patches that are breathable and hypoallergenic. Another thermoplastic polymere called polyethylene terephthalate (PET) offers excellent transparency, good flexibility, and is easy to fabricate.

Soft Silicones

The latest material innovations has been the development of soft silicone elastomers. Not only do these materials offer great flexibility, but they are prized for their ability to conform to a wide variety of shapes and textures. This puts them at the forefront of stretchable, wearable sensors. Some of the top soft silicone elastomers are: EcoFlex®, DragonSkin®, and Silbione®.

The field of wearable technology materials is advancing at breakneck speed. Here at Best Technology, we are keeping on top of these trends so that we can continue providing the most advanced flexible printed circuit boards to our customers.

flexible circuits

flexible circuits

Space Is Money – How Flex PCB Can Help You Save Big

In the electronics industry, the name of the game is lighter and smaller. Consumers want sleek, beautifully designed computers and gadgets that still pack a big computing wallop. That is to say, for designers, at least, space is money.

If you can make your product smaller and less bulky than the competition, you will gain the market advantage. Flex printed circuits boards (aka flexible circuits or flexible pcb) are designed to give you all the space you need to create innovative new product designs.

Now let me talk about the trouble with Rigid Printed Circuit Boards

If you’ve ever had to work with rigid printed circuit boards before, you know how much of a nightmare they can be. You have to find space for them and work the rest of the components around them. Flex printed circuit boards give you back control over your design. Because they can flex, you can fit them into smaller spaces, which frees up space for more components, that can make your product more powerful, more efficient, or both. They fold, twist, and roll, making it easy to find a spot for them. This also gives you the opportunity to place other parts in a better order for the most efficient sub-assembly possible. Better part placement refers to less energy waste, a longer battery life, a more solid overall configuration, and a better operating product. It also means you have control over how you map out the inner workings of your product for optimum setup.

In the fierce electronics industry, even a slightly better assembly can put you ahead of your competition and turn your product into a bestseller, while they get left in the dust.

Flex PCBs also weigh less. Even shaving off a few ounces on your product could make a noticeable difference that will make it easier for your customers to use it, wear it, and carry it. The more they want to interact with your device, the more hooked they’ll become.

Want to learn more about flex PCBs? Just contact Best Technology. Do not hesitate any more. We can explain how they work and help you determine if adding them to your next product will save you space and money.

Introduction to A Flexible Circuit Coverlay

During the flexible printed circuit board manufacturing process, a flex circuit coverlay (aka coverfilm) is used to encapsulate and protect the external circuitry of a flexible circuit board.
flexible circuit coverlay serves the exact same function as solder mask that is used on a rigid printed circuit board. The difference with a flex coverlay is the needed element of flexibility and durability it provides to the flex PCB design.
The coverlay consists of a solid sheet of polyimide with a layer of flexible adhesive that is then laminated under heat and pressurized to the circuit surfaces. The required component feature openings are mechanically created using drilling, routing, or laser cutting.
Typical coverlay thickness is 0.001″ polyimide with 0.001″ of adhesive. Thicknesses of 0.0005″ & 0.002″ are available, but only used as needed to meet specific design requirements.
For more information visit our website to learn more about our flex & rigid-flex PCB manufacturing process!

When You Want Your Flex Circuit Boards on Time

If you have a new product launch on the books, and it’s going to be a big project. Your PR department is already spinning the press release, and your marketing department has been laying the groundwork for months. Suddenly, your flex circuit board vendor says that they’re running two weeks behind. That’s not a problem, is it?

As a business owner, you can’t afford to miss a product launch deadline or to run out of inventory when your customers are eager for your products. That means every single step in your supply chain must be reliable. If one vendor falls behind, the entire system grounds to a halt, meaning costly delays or mad scrambling, which is unacceptable.

Then,when you are seeking for vendors, consistency is the key. At Best Technology, we understand how important it is to meet your deadline. We are experts in manufacturing flexible circuit boards and rigid flex circuits based on the highest quality standards and we have accumulated much experiences since our establishment on June 28, 2006. We also own an excellent shipping department capable of getting your order to you on time wherever you are. You can rest assured we will not fall behind and cause delays!

If you are looking for a new flex circuit vendor or are unsatisfied with your current vendor, contact us today. We will give you a surprise.

Imaging Process for Flexible Circuits

One of the first steps in manufacturing a flexible circuit is to build a circuitry pattern. In order to define the circuit pattern correctly, one needs to understand the basic process for building a circuit. Processes tend to fall in one of the following two categories:

1. Subtractive

The substrate begins with copper bonded to the dielectric, the unnecessary metal is removed; the remaining metal defines the circuit traces. The basic process steps for a subtractive process are:

Create resist pattern

Etch away exposed metal

Remove resist

Continue to process

Many possible methods are adopted for the creating the resist pattern, the following are two of the more common ones.

I. Screen Print

Screen print resist pattern

Cure resist

Etch

Remove resist

II. Photo Image

Apply resist coating

Photo expose image onto resist

Develop away unexposed resist

Etch

Remove resist

Screen printing stands for a tool made by forming a negative of the desired pattern on a woven screen mesh. The resist material is pushed through the open mesh and forms the circuit pattern on the substrate. The initial state of the resist material is normally a paste or semi-liquid. After the material is applied to the substrate, the resist needs to be cured. The cured resist protects the covered copper areas during the etching process.

In regards to photo imaging, a photo tool is created that is the negative of the desired pattern. The photo tool is placed over the resist coated substrate and flooded with a UV light. The photo tool allows the light to cure the resist where the pattern is to be created and blocks the light everywhere else. The UV light causes a chemical reaction in the resist and transforms it to have the chemical and physical properties to withstand the etching process. The developing solution strips away all the “un-cured resist” exposing the bare copper to be etched away.

2.Additive

The substrate begins with just the bare dielectric (possibly with a seed coating), the metal is added to the surface to directly form the circuit pattern. The basic process steps are:

Apply conductive material

Cure conductive material

Continue to process

The additive material is usually a paste and is often applied by screen printing. The applied paste is then cured to reach its optimal properties. Materials that have outstanding conductive properties tend to require very high temperatures to cure. The dielectric substrate for flexible materials is a limiting element for the temperature level and tends to restrict the types of additive materials that are used to create a circuit pattern. Generally speaking, the electrical, physical and chemical properties of this type of circuit are significantly lower than the properties achieved via the subtractive process.

Saying Goodbye to 2018 and Embracing 2019

In order to goodbye to 2018 and embrace 2019, Best Technology hosted a year-end party on January 18, 2019. The party began with a passionate speech by the general manager. He complimented the achievement of last year and talked about the development direction of 2019.

Peter gave a speech
Peter gave a speech

Next, we held an award ceremony to recognize in acknowledgement of people’s work for the company. Although we have gone through a series of hard time due to the complicated international situation in 2018, our flex circuits still got the first place. Mrs Celine won the sales champion of flexible PCB.

Celin won the champion of sales
Celin won the champion of sales

In the year-end party, our team gave a lot of talent shows to enrich the entertainment programs, including singing, dancing, magic and so on. Our hearts got together to enjoy the happiness and relaxation.

Interesting dance
Interesting dance

In order to reward those who have worked hard for a year, we set up an activity of prize draw, too. In this way, the party reached to a climax.

Prize draw
Prize draw
https://www.bestfpc.com/blogimages/2019/01/21/family-picture-s.jpg
Family picture to keep the memory

The party came to an end with a song called Tomorrow Will Be Better and we believed that we will hand in hand to create a brighter future for Best Technology in 2019. Meanwhile, we will also try our best to give you competitive supply of single side flex circuits, double side flex circuits, rigid-flex circuits etc. in 2019.

3 Notices for Layout Double-Side BGA for FPC

Layout double-side BGA for FPC is used in some products, but since the complexity of manufacturing process and maintainability need to be taken into consideration, the designers need to pay attention in followings:

1. Do not overlap when layout double-side BGA and a certain of distance is required left. The reason why to do that as it is difficult to repair if there is poor BGA on one of sides.

2. In order to prevent the BGA on the bottom from melting during the second time reflowing, it is required to decrease the bottom temperature in the second time reflowing. It is better to decrease the bottom temperature lower than to the melting temperature of solder joints to ensure that the solder joints do not melt again. What’s more, you can fix the bottom BGA with jig.

4 ways to increase deformation resistance for flex circuits:

1. The stress resistance of BGA can be strengthened by a supporting iron frame around it.

2. The stress resistance of BGA can be strengthened by gluing around it or on the corresponding back of flexible PCB.

3. If you aim at protecting the BGA, then you are able to add screw to fix the other parts around BGA. In this way, the other parts around BGA won’t deform easily.

4. Strengthening the outer shell of flex circuits to avoid its deformation affecting the inner circuit.

As the premier expert in flexible circuit fabrication, Best Technology has a team which always striding for high quality flex circuits and services. If you would like to know more about Best Technology, please give us a call at 0755-29091601 or view our website: https://www.bestfpc.com/