As we all known, some customer need to do following assembly in their side when received the bare boards. In order to facilitate customers for subsequent assembly, we’ll ship out boards in panels. So, what’s the difference between FPC and PCB paneling connection mode?
For FPC , we often use connecting tabs to connect the boards.
For Rigid PCB, we often use V-cut and connecting tabs(with stamp holes) to connect the boards.
For Rigid-flex PCB, we’ll use connecting tabs(without stamp holes) in flex part, and use connecting tabs(with stamp holes) in Rigid part.
Take the Rigid-flex PCB for example, if the boards are easy to fallen from panels when do assemble, how to improve the design?
There are two direction we can go, one solution is add more connecting tabs in paneling, another solution is broaden the width of connecting tabs.
Hope our suggestion are helpful for you. If any further question want to discuss with us, pls feel free to contact us at email@example.com.
Do you know what is the EMI shield? Do you know what is the EMI shield used for and what kind of products need to add the EMI shield? Today let’s know why the FPC or rigid flex add the EMI shield together.
When your flexible PCB or rigid-flex PCB application requires limits in electromagnetic and /or electrostatic interference, EMI shielding should be applied.
Electromagnetic interference (EMI) also called radio-frequency interference (RFI), when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade and effect the performance of the circuit or even do not get work. EMI is caused by electrical pulsing.
What’s is our EMI shield?
With EMI shielding film design, the Flexible PCB has best flexibility as well as the thinnest overall thickness. Compared to silver ink printing and copper layer design, the flex circuit cost will be lower, and the shielding capability will be in a higher degree. No need extra shielding material, like metal cover. EMI shielding film such as Tatsuta can replace the copper layer design, then to save cost without compromising on the flexibility of the board.
EMI consists of an additional layer of selectively specialized laminate on the surface of the coverlays. It has 3-layer construction consisting of an electrically conductive adhesive, a reinforced layer and an insulation layer. The insulation layer is black in color as well as friction resistant. The EMI shielding film is laminated under heat and pressure. The conductive adhesive flows into the coverlay opening which then adhere and electrically connects to the ground. Attached the EMI shield stack up for your reference, hope it will be helpful to you.
The normally used EMI shield is TSS200 from Toyochem. The thickness is 200um. It has the excellent flexibility, electrical conductive reliability, chemical resistance, non-Halogene and UL type. If you would like to learn more details, please contact with me.(firstname.lastname@example.org), we will be very glad to share the TS 200 EMI shield specification with you. Attached some of our FPC and Rigid flex with EMI shield for your reference, hope you will be interested in.
EMI Shielding application filed
Our EMI shield required customers are mainly specialize in wireless communication, 5G phone, radar, drone, camera and new energy automobile. EMI shield is becoming more and more popular in the designs of flexible printed circuit and rigid-flex printed circuit board. Many flexible PCB or Rigid-flex circuits are sensitive to either absorbing or emitting EMI. If EMI shield is out of control, it can negatively impact the performance of the design and or effect the circuit function.
Have you ever been faced don’t how to choose a suitable stiffener for your flex circuit board issue? Do you know t how many types of stiffener will be used for flex pcb? What is the reason why we need to add the stiffener on the flex PCB? Today let us study flex circuit board different types of stiffener together.
The types of FPC stiffener
In generally, there are only 3 types of stiffener we usually used. Polyimide(PI), FR4, and stainless.
1.Polymide PI stiffener:The tolerance can be controlled +/-0.03mm, high precision and have high temperature resistance（130~280 Centigrade)
2.Stainless Stiffener: Need to do assembly by hand and the process is more complicate, the cost will be a little higher.
3.FR4 stiffener: If the thickness is below 0.1mm, the tolerance can be controlled +/-0.05mm. If the thickness is more than 1.0mm, the tolerance is +/-0.1mm
Recently, many customers asking me what is the flex PCB tooling included? And why we need to opening a tooling? How many types of tooling for flexible circuit? How to choose the suitable tooling for flex pcb?
Today, let’s learn about the Flex PCB tooling together. The FPC tooling is always used for cutting the FPC outline and coverlay. So it has included the FPC outline and coverlay tooling.
For samples production, normally we will open a tooling to save the cost and time for our customers, because the tooling will be scraped if you update the new version. So we will use the laser machine to cut outline and coverlay. But the productivity of laser cutting is longer than a tooling cutting the outline, that’s why we need to opening a tooling for volume production.
In generally, there are only four types of tooling in our production process.
1.Normal tooling, it is the most common used for most the flex pcb to cutting the coverlay and outline. The FPC appearance tolerance is 0.1mm, and the gold finger size tolerance range can be controlled at 0.15mm.
Mediumn silking tooling: The precision is high, and the lifespan is better. The punching times is around 200,000 times. The punching effect appearance is good and smooth. The tolerance is 0.07mm. But the cost is high, and the tooling making time is longer than normal tooling
Precision tooling: The surface is very smooth, it is usually used for tolerance very strict flex pcb. The gold finger tolerance can be controlled +/-0.05mm. But the cost will be also much higher than normal tooling.
4.Knife tooling: It is usually used for cutting the simple flex pcb, more than 500 mm length flex circuit board and adhesive. The tolerance is around +/-0.2mm.
Do you still have any questions about the flexible circuit board tooling? If yes, please feel free to contact Best Technology at email@example.com. Looking forward to receiving your feedback.
Assemble components on a flexible printed circuit board (FPC) requires that when the smart wearable industry becomes more and more popular, due to the assembly space, the surface mount of SMD on FPC has become one of the development trends of SMT technology. But flex PCB is more difficult to assemble than rigid boards, because it is not as sturdy to assemble. Today let’s learn something about the difference between assembling flex and rigid boards. 1.Soldering process Like the rigid PCB process, the solder paste is covered on the flexible board and the rigid-flex board through the operation of the stencil and solder paste printer. But the surface of FPC is not flat, so we need to be fixed with some fixtures or stiffeners. Normally we will stick stiffener for component area of flex PCB, you can refer to below sample picture. Stiffeners contains PI stiffener, FR4 stiffener and Sheet steel stiffener.
SMT component placement
Under the current trend of miniaturization of SMT components, small components will cause some problems during the reflow soldering process. If the flexible circuit is small, extension and wrinkles will not be a significant problem, resulting in smaller SMT frame or extra mark points. If you do not want to stick stiffener on the bottom side of components, maybe you need flexibility after assembly. So SMT fixture would be a good choice, you can refer to below pictures for fixtures(fixture vs fixture with flex PCB).
Reflow soldering process
Before reflow soldering, the flexible circuit must be dried. This is an important difference between the flexible circuit and the rigid PCB component placement process. In addition to the dimensional instability of flexible materials, they are also relatively hygroscopic. They absorb water like a sponge. Once the flexible circuit board has absorbed moisture, it has to stop reflow soldering. Rigid PCB also has the same problem, but it has a higher tolerance. The flexible circuit needs to be preheated and baked at ~225° to 250°F (like below pictures). This preheating and baking must be completed quickly within 1 hour. If it is not baked in time, it needs to be stored in a dry or nitrogen storage room.
If you would like to know details about the assembly of flex PCB, please feel free to contact Best Technology at firstname.lastname@example.org
Have you ever been have trouble in selecting the solder mask and coverlay when you are design a flex pcb? Solder mask and coverlay has the same basic function of insulating, do you know the difference between solder mask and coverlay? Is it possible to make the solder mask and coverlay overlap together for insulating? Do you think the flexible solder mask is the same as rigid printed circuit solder mask?
1)Design: Actually, coverlay is widely used for flexible printed circuit board. Because of most of flex pcb will need to add the PI/FR4 stiffener and EMI shield. But if there are BGA pads and dense solder mask opening area, limits the minimum size of openings and the minimum web of material then can be retained between adjacent openings. I would like to share a coverlay and solder mask overlap together FPCB with you. The coverlay is applied first and the solder mask second with a slight overlap onto the coverlay to prevent any gaps in the combined layer. This kind of design have much higher requirements for our production to ensure your functional and reliable design. Below picture is a coverlay and solder mask overlay together FPCB, hope you will be interested in.
If the coverlay opening is square, the minimum size for coverlay is 0.6mm, and space is 0.25mm. Otherwise you need to print solder mask. If the coverlay opening is round, the mimimum size for coverlay is 0.25mm, and space is 0.15mm. Otherwise you need to print solder mask. Because too small coverlay webs will be easily damaged or broken during manufacturing process, and the limited of adhesive may not allowed for a good lamination. Coverlay openings may also exhibit a small amount of adhesive squeeze out into the openings. Then the resulting design rules for coverlay are significantly different than those for solder mask. Attached the coverlay square and round opening picture for your reference, please kindly check it.
2)Thickness: Below is the pure green solder mask flexi pcb picture, it do not need to add the stiffener for PCBA (SMT assembly), and there are no BGA area, why it choose to use the green solder mask instead of coverlay? The normal coverlay thickness is 27.5~50um. And the solder mask thickness is 8~12um. Due to the customers need the ultra thin flex pcb. Then we suggest the customer to use the solder mask instead of the coverlay.
3)Color: The most popular coverlay color is yellow, we usually prepared the yellow, white, black coverlay in stock. Solder mask is available in a wider range of colors: green, black, white, yellow, etc. Please kindly note that the flex pcb solder mask is quite different to rigid pcb. The flex pcb solder mask cost is much higher than FR4 PCB.Because the flexible circuit board solder mask the withstand bending and high temperature is better than Rigid FR4 PCB. But the coverlay and solder mask for flex price is the same for us.
If you have any comments, warmly welcome you to contact us. Once we received your news, we will reply to you immediately. Looking forward to receiving your inquiry.
In the production of FPC, normally we need to add different stiffener to meet the total thickness or hardness, such as PI stiffener, FR4 stiffener and stainless steel stiffener. But the FR4 stiffener after laminated is very similar to the rigid-flex PCB, especially there are also have drilling holes in FR4 stiffener.
Do you know how to identify FR4 stiffener and rigid-flex PCB? Please refer to the below picture. On flex PCB, you can see there are many PTH holes, maybe these boards are need to insert connectors and connect it to other products. So they need the hardness in this area.
From the left sample, we added the FR4 materials on bottom side, there are also have vias on stiffener, but no copper in vias, so this is FR4 stiffener. It can only increase the hardness of flex. From the right sample, the green part are still FR4 materials, but we plated copper for all vias, so it’s a rigid-flex PCB.
Rigid-flex board has many production processes, high production difficulty, low yield rate, so its price is relatively expensive and the production cycle is relatively long than flex PCB. If the FPC with FR4 stiffener can meet your requirements, then it would be a better choice for you.
If you have any other question about stiffener or rigid-flex PCB, please feel free to contact us at email@example.com
Today I’d like to share what’s the difference between Adhesive PI and Adhesiveless PI.
Item 1: Adhesiveless PI stack up
As you can see in above stack up, there is no adhesive connect the Copper layer and Polyimide.
There are four advantages of adhesiveless PI:
As you know, the thickness of adhesive is around 12.5um, 15um, 20um. If you have strict requirement for the whole board thickness, it will be a good choice to use adhesiveless PI.
Adhesiveless substrate is thinner than adhesive substrate, so it’s bending is better.
3. Heat resistance
Due to the adhesive have poor performance in heat resistance, so without the adhesive, the adhesiveless base material have better heat resistance.
Under the same temperature, such as 200℃，the tearing strength of adhesiveless PI change a little. But the tearing strength of adhesive PI material rapidly decrease.
4. Dimensional stability
The dimension of adhesiveless board change very small when the temperature increase. Even under the temperature of 300℃, it’s dimensional changing rate is no more than 0.1%.
Good dimensional stability will be great help for fine wiring process.
5. Chemical Resistance
The adhesiveless substrate have good performance of chemical Resistance, it’s tearing strength have no obvious change with time increased.
The adhesive base material has poor chemical resistance, so it’s tear strength decreases greatly with the increase of time.
The only disadvantage for adhesiveless PI is it’s a little expensive than adhesive PI.
Item 2: Adhesive PI stack up
As you can see, the thickness of 2 layer adhesiveless FPC is 0.19+/-0.03mm.
The thickness of 2 layer adhesive FPC is 0.23+/-0.03mm.
If you need thicker thickness, the adhesive PI might can meet your requirement, the cost will be much lower than increase copper thickness or PI thickness.
There are two mainly advantages for adhesive PI:
Anyway, if your project need thinner thickness or smaller line width and space (0.05mm), adhesiveless PI will be the best choice. Welcome to contact us at firstname.lastname@example.org if you need to know more details.
Have you ever been heard about the dual access flexible circuit? Why it named dual access flexible circuit? After you read my e-mail, you will find the answer.
Dual access flexible circuit board is similar to double side FPC, but it has different stack up to double side FPC. Why it named dual access FPC? Dual access can access to both side by copper, so it named the dual access flexible circuit. Dual access flex PCB only have 1 layer copper, and coverlayer on both side. They can connect both side by layout through coverlayer opening, and do not need to drill the holes like 2 layers flex PCB to connect both side.
Working principle: The coverlayer play the role as an insulator, the copper is a very good kind of conductor. One side is anode, and the other side is cathode. If they the current flow, they form a closed loop circuit.
It can be connected to both side through copper, and do not need to make a through hole. If it is 2 layers FPC. You have to make a through hole to connect both side.
2. The appearance will be more beautiful than 2 layers flex PCB. Because we can conduct by trace, it will be more beautiful than through holes to conduct.
Dual access circuit disadvantages:
Complex production process: The production process is similar to 2 layers flex circuit, but it will be more difficult and complicate compared with 2 layers flex PCB. It is easy to scrap. And many factories can not make dual access circuit board due to production technique.
Easy to wrinkle. Because the dual access is very thin. Only one copper and two coverlayers, it will be easy to tear up. When it comes to laminate process, is also very easy to laminate wrinkles and blister.
If you have any questions or would like to learn more details, please feel free to contact us.
Recently, Best Technology has completed 14 years of its glorious journey. Every small step is worth celebrating. On June 26, 2020, our founder, Peter, Emily, group leaders and all the employees spent this unforgettable festival in union.
On Best Technology successful journey, Peter stressed- “These past 14 years have been a period of growth and a learning experience for us as we went through several trials and errors till we deliver successful business. Today we are proud of the fact that our employees can make great progress day by day after training with us and feel confident taking on tough project-related challenges,thanks for all the endeavour from employees and thanks for the great support from our suppliers and customers. Best Technology’s continuous development can not do without them.”
We have come a long way from 2006 when we started off with just 1 people(Peter). Today we are proud to announce that we have nearly 100 employees and many sister companies spread all over China mainland and also have customers in over 150 countries around the world.
From above, it is evident that there has been a staggering growth in the number of employees in the span of 14 years. This enhanced employee strength has built the roadmap to Best Technology’s success.
The above graph presents our company’s growth against the years 2006 to 2020. It can be seen that the growth rate is very high from 2006($8000) to 2019($6560,000). At this year 2020, Best Technology still keeps growing with increasing sales volume in spite of COVID-19 outbreak.
Best Technology’s unique journey has been a brick-by-brick progress and has entailed years of efforts. Our company’s commitment in becoming world class distinctive solution of printed circuit board and metal domes in 2025 has paved the way to the series of milestones achieved. These are equally appreciated by the correct leadership of our chairman, Peter.
The primary aim of our company has been to equip the professionals with all possible accoutrements to tackle on-job challenges. Today’s ever changing face of businesses demands deeper knowledge, quality, and on-time delivery. Customers are always looking out for continuous and improved delivery. The best means to achieve the same is to keep improving.
We will continue our journey towards innovating the new ways of learning, delivering excellence to the customers and lending a hand to achieve professional goals.
What’s more, Best Technology’s 14th-year anniversary celebration is a solemn procession of efforts and dedication of the trainers and staffs who have spent their quality time to provide the best services and meet more expectations of the ever evolving PCB world.