FPC Flexibility Influencing Factors

During PCB design, FPC flexibility plays an important part and FPC flexibility is influenced by the followings:

(1)From the perspective of FPC material itself, FPC flexibility is influenced by the followings:

First, molecular structure and direction of copper foil(i.e. copper foil types);

Folding strength of RA copper is obviously superior to ED copper.

Second, thickness of copper foil;

In terms of the same type, the thinner the copper foil, the better the folding strength.

Third, types of adhesive used by substrate;

flex pcb
flex pcb

As a general rule, the flexibility of epoxy glue is better than that of acrylic adhesive. So, if high flexible material is required, epoxy glue is recommended. Moreover, the adhesive with high tensile modules can improve flexibility.

Fourthly, the thickness of adhesive;

The thinner the adhesive, the softer the material. Thin adhesive can improve FPC flexibility.

Fifth, insulation substrate.

flex pcb
flex pcb

The thinner the insulation substrate(PI), the softer the material. Thin insulation substrate can improve FPC flexibility. And FPC flexibility will get better if PI with low tensile modules is used.

In conclusion, for material, type and thickness are the most important 2 factors influencing FPC flexibility.

(2)From the perspective of FPC technology, FPC flexibility is influenced by the followings

First, symmetry of FPC combination;

After substrate is pasted with coverlay, good symmetry of material on both sides of copper foil can improve flexibility. This is because they bear the same stress when bending. PI thickness on both sides of PCB tends to be the same, and thickness of adhesive on both sides of PCB tends to be the same.

Second, control of lamination technology.

During coverlay lamination, the adhesive is required to be completely filled into the middle of the trace, and there can be no delamination. If there is delamination, it is equivalent to bare copper bending, which will reduce the number of bending.

If you have any queries, comments or suggestions on FPC flexibility, feel free to contact us, and we have 24-hour online customer services.

How to calculate bending radius of fpc?

 The most frequently asked question we received regarding fpc is “how much can I bend a fpc?” So, we would like to share how to calculate bending radius of fpc with you today.

fpc
fpc

When fpc is bending, the stress borne by both sides of center line is different. Pressure is inside of bending face, while tension is outside. The stress has something to do with thickness and bending radius of fpc. Excessive stress will lead to delamination of fpc, fracture of copper foil and so on.Therefore, the laminated structure of fpc should be arranged reasonably in the design, so that the lamination at both ends of the center line of the curved surface should be symmetrical as far as possible. At the same time, the minimum bending radius of fpc should be calculated according to different applications.

Situation: the minimum bending radius for single-sided fpc:

 Bending Radius for Single-sided fpc
Bending Radius for Single-sided fpc

  The calculation methodR=c/2[100-Eb/Eb]-D
WhereinR=Minimum Bending Radius(unit:”m); c=Copper Thickness(unit: ”m); D=Thickness of Coverlay(unit:”m); EB=Copper Elongation Desired(Measured as a Percentage)
Copper elongation desired also differs among various types of copper.

A.The maximum copper elongation desired for RA Copper ≀16

B.The maximum copper elongation desired for ED Copper ≀11

Moreover, value for copper elongation desired for the same material will be different in different applications. For one-time bending, the limit of the critical state of fracture is used (for RA Copper, the value is 16%). For bending installation design, use the minimum deformation value specified by IPC-MF-150 (10% for RA Copper).For dynamic flexible applications, copper elongation desired is 0.3%. For magnetic head applications, copper elongation desired is 0.1%. By setting the copper elongation desired, the minimum bending radius of fpc can be calculated.

Dynamic flexibility: In these applications, copper functions through deformation. For example, the phosphorus and copper metal dome in the IC card seat, i.e. the part where the IC card contacts with the chip after being inserted, and the metal dome is constantly deformed in the process of inserting. This kind of application is flexible and dynamic.
If you have any queries or comments on bending radius of fpc, contact us anytime.

Do You Know the Standard Flex Stackup for 1 Layer, 2 Layers, or Multilayers?

Standard flex stack up for 1 layer flex pcb:

1 layer flex pcb stackup
1 layer flex pcb stackup

This is the simplest flex pcb. Generally, base material and adhesive and copper foil are used as raw materials, or protective film and adhesive are used. Firstly, copper foil needs to be etched to get traces required. Protective film needs to be drilled to expose pad. Both are combined by using rolling process after cleaning, then the exposed pad should be electroplated with gold or tin for protection. In this way, the flex PCB is finished and can be punched into small flex pcb.

Standard flex stack up for 2 layers flex pcb:

2 layers flex pcb stackup
2 layers flex pcb stackup

When the traces of flex pcb are too complicated, the 1 layer flex pcb can not meet the needs of wiring, or needs copper foil for grounded shield, 2 layers flex pcb or multilayers flex pcb can be used.

Standard flex stack up for multilayers flex pcb:

The via holes are added to make multilayers flex pcb different from 1 layer flex pcb, so that copper foil in each layer can be connected. Generally, for base materials and adhesive and copper foil, the first processing technique is to make via holes. The base materials and copper foil should be drilled firstly and then electroplated with copper of certain thickness after cleaning. Thus the via holes are finished. The subsequent manufacturing techniques of multilayers flex pcb are almost the same with 1 layer flex pcb.

For example, here is the standard flex stack up for 4-layer flex pcb

4 layers flex pcb stackup
4 layers flex pcb stackup

There may be some differences among the stackup for 1 layer flex pcb, 2 layers flex pcb and multilayer flex pcb, but similarities also exist among many manufacturing techniques of flex pcb. Different techniques are just added in some basic places, so as to be applied in different fields.

If you have any queries or comments about flex pcb, welcome to contact us anytime.

Special Women’s Day Gift for Lady in Best Technology

Tomorrow March 8th, 2020 will be the Women’s Day! As it’ll be Sunday, so everyone in Best Technology get the gift today: One box of facial mask, one bottle of eye cream, and one bottle of moisturizer

Special-Women’s-Day-in-Best-Technology-March7-2020

We hope every lady in Best Technology keep happy, beautiful, while they’re working so hard, even working in middle night, in order to give our customers immediate reply. This is one of reason why you can see email reply within one hour sometimes even in the evening!

Special-Women’s-Day-in-Best-Technology-March7-2020

It’s the first time that every girl in Best Technology take a photo with a face mask! Everyone in Best Technology want the coronavirus to be finished ASAP, so that everyone doesn’t need to have a face mask and global economic turn back to normal level. At that time, we can take a photo again so that you can see the smiling face of our girls😊 and we believe that day will come in soon!

As we are resume, so if you want to know anything about flexible circuit, rigid-flex, feel free to contact us.

The status quo of Chinese society under Coronavirus spreading

This is another test for China and the world community after SARS. At this moment, any slamming, taunting, fanning, and gloating are all manifestations of lack of humanity. The virus does not recognize the country, nation, race, rich or poor. There is no difference in virus transmission.

China’s powerful system and the effective measures it has taken to prevent and control novel coronavirus-related pneumonia are rarely seen in the world, Director-General of the United Nations’ World Health Organization Tedros Adhanom Ghebreyesus said on Tuesday.

Ghebreyesus made the remarks while meeting with State Councilor and Foreign Minister Wang Yi in Beijing.

The WHO and the international community highly appreciates, and fully affirms the decisive measures the Chinese government has taken to deal with the outbreak and also thank China for its tremendous efforts to curb the spread of the contagion, he said.

China set a record in identifying the pathogen in a short time following the outbreak of the contagious disease, Ghebreyesus said, and he praised the country’s timely sharing of the virus’ DNA information with the WHO and other countries.

You can see more report details from WHO https://www.who.int/news-room/detail/28-01-2020-who-china-leaders-discuss-next-steps-in-battle-against-coronavirus-outbreak

WHO meeting with China leaders

I don’t know the source of the so-called news of many foreign friends. As a Chinese, I saw the initial panic, and I also saw the current stability.

In response to the GVM’s call, the school has delayed the start of school, and most companies have extended the Spring Festival holiday from original Feb 2nd to Feb 9th and resume on Feb 10th. This is not a sign of lack of confidence in controlling the virus, it is one of the measures to put people’s lives first.

Everyone knows that this is the most effective way to control the spread of the virus.

I went to supermarkets, fruit shops, etc., and there was no snap-up like it was fabricated by some media. Prices have not skyrocketed. The price department is also strictly controlling the prices of daily necessities to protect people’s daily lives.

Relevant departments have made the unified deployment of some protective supplies such as masks to ensure timely and adequate supply. Which country can make such an appropriate response in the first place?

It’s really boring to stay at home every day, but who wants to joke with life? As someone who is very busy working every day, having more time to spend with his family may also be a good thing. After all, too many people complain that the Spring Festival holiday in just a few days is not long enough.

The internet is well developed. Although I can’t meet my relatives, friends, colleagues to celebrate the Spring Festival, isn’t it convenient for video chat, using WetChat of Facetime for people around the word? Why not give up the temporary joy in exchange for the safety of life?

We are very grateful to the medical staff, community service staff, and social service staff who gave up their holidays and took great risks in helping patients, maintaining social stability and creating a more secure environment.

I am grateful for living in such a country. I believe that every Chinese thinks so.

In such a severe situation, in order to eliminate the virus as quickly as possible and ensure the safety of people’s lives, any measures are reasonable.

Every Chinese should understand and understand. 

People of all countries in the world who have experienced various natural and man-made disasters should marvel at China’s timely and effective measures.

As an international trade practitioner, I have sincerely explained to each of my customers our current status. We don’t need to whitewash or conceal anything, because we have done our best to do a good job.

I believe that the Chinese people will be able to eliminate the disease as soon as possible. Because we eliminated more severe SARS than this time in 2003, didn’t we?

Here everyone in Best Technology in China was in good health condition, and our office & facility will be opened on Feb 10th. During that period, our sales reps. will try to reply the email ASAP and thanks for the caring from all of our customers around the word! Much appreciated!

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 25-50Όm.

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.

Best Technology Wishes You Merry Christmas and Happy New Year 2020

Christmas and New Year is just around the corner. Merry Christmas to everyone. As the year 2019 is coming to an end, the team at Best Technology would like to wish you a happy, healthy, and prosperous New Year 2020. We believe that it is time to focus on the year that has gone and say thanks to all valuable people who helped us to become trusted and well-known PCB manufacturers in China.

Best wishes

Best wishes

We acknowledge that the year 2019 has been a surprise for us, wherein we got several opportunities to serve for our customers. The challenges that came along with these opportunities has helped us refine ourselves for better and stand tall among all our competitors. Being an industry-leader in flex, rigid, and rigid-flex PCB manufacturing, we could easily fulfill your orders in the specified time and in compliance with required specifications. Although technology plays a major role, we could never have achieved this success without our employees, who always made the most of their abilities to help meet our commitment of on-time deliveries.

rigid flex pcb

rigid flex pcb

On this holiday season, we would love to send our warmest wishes to the team who stood by us through challenges and our valuable customers for investing their time, money, and faith in our capabilities. This helps to serve you better. We are expecting to achieve more milestones in the upcoming year. This is not possible without your supports and faith. We hope this relationship will grow stronger in the New Year.

The entire team of Best Technology Wishes you a Merry Christmas and Happy New Year 2020 again!!!

For your easy reference, below is our holiday schedule:

Christmas Day: We will be closed on Dec 25, 2019 and resume working on Dec 26, 2019

The New Year: We will be closed from Jan 18, 2020 to Feb 1, 2020 and we will resume working on Feb 2, 2020

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.

We will be exhibiting at PCB West 2020

Best Technology, a China- based assembly manufacturer will be exhibiting at PCB West 2020 in Santa Clara, CA at booth No. 514 on September 9, 2020(Western Time). Actually, we have participated in this exhibition for continuous 2 years. Here are some pictures for your reference. At Best Technology’s exhibition booth, attendees will be able to learn more about our company for PCB manufacturing and assembly technology.

At the exhibition booth

At the exhibition booth

Celine is talking with customers

Celine is talking with customers

Marina is talking with customers

Marina is talking with customers

Coco is talking with customers

Coco is talking with customers

At the exhibition booth

At the exhibition booth

For interested professionals, Best Technology had on hand experts to offer detailed insights and experience on PCB assembly, covering prototype and low/high-volume production. For more information on PCB assembly and fabrication, please visit Best Technology’s exhibition booth No.514 at PCB West 2020.

You will see 10mm to 1,500 mm flexible circuit board, from 2 layer rigid-flex circuit to 50 layers, 1/2 OZ copper to 3 OZ, 0.15mm extra thin FR4 PCB to 30 OZ heavy copper, turn-key service from components sourcing,board fabrication(FPC, PCB, MCPCB, Ceramic PCB) and final assembly with programming and testing.

You are warmly welcome to talk more to see how we manage the components wastage and efficiency to help save your time, money and energy.

About PCB West

SANTA CLARA, CA, PCB WEST 2020 PCB West is an annual event sponsored by major electronics manufacturing vendors and attended by electronics engineers, technicians, managers and more. PCB West is a marketing, product launching and career enhancement event that offers a 1-day exhibit and a 3-day conference. You will get more closely connection with new Technology in PCB field from PCB West.

Welcome to visit us at Booth 514 on September 9, 2020(Western Time).