Flexible circuits (also variously referred to around the globe as flex circuits, flexible printed circuit boards, flex print, Flexi-circuits) are members of electronic and interconnection family. They consist of a thin insulating polymer film having conductive circuit patterns affixed thereto and typically supplied with a thin polymer coating to protect the conductor circuits. The technology has been used for interconnecting electronic devices since the 1950s in one form or another. It is now one of the most important interconnection technologies in use for the manufacture of many of today's most advanced electronic products.
High Temperature and High-Density Applications
In many cases, flex circuits are made of polyimide or a similar polymer. This material dissipates heat better than most rigid circuit board materials. For this reason, flexible circuits can be placed in inconvenient locations where heat would impact the performance of a rigid circuit board.
Flexible circuit boards can be designed to withstand extreme temperatures – between -200° C and 400° C – which explains why they are so desirable for borehole measurements in the oil and gas industry.
In fact, because of these conditions, and the need for small, unobtrusive devices in most industrial environments, flexible circuits represent the first choice for engineering design in most industrial sensor technologies.
High-temperature resistance comes usually comes with good chemical resistance and excellent resistance to radiation and UV exposure as well. Combined with the ability to control impedances in high-density circuit board designs, flexible circuit designs offer many benefits to manufacturers.
Comparison between the Poyester (PET) and Polymide(PI) material
The flex pcb raw material and stack up will decide the flex circuit quality. According to the market demand, there are three types of base raw material used for Flexible circuit board. Poyester(PET), adhesive Polymide (PI) and adhesiveless Polymide (PI) .
Do you know the difference between the PET and PI material? If not, let us learn about it together now.
Attached is a form for your reference, hope it will be helpful you. And you can choose the right raw material according the below form.
Features
Polyester(PET)
Adhesive Polymide
Adhesiveless Polymide
Flexibility (2mm radius)
Bad
Good
Best
Tear strength
800g
500g
500g
Strip strength in the air
1050N/M
1750N/M
1225N/M
Eatching>=20%
BEST
Bad
Good
Working temperature
80
85~165
105~200
Chip
Bad
Good
Best
The advantages and disadvantages of the PET and PI materials
Material
Advantages
Disadvantages
PET
fewer production process; cheaper price; less lead time.
cannot pass through the soldering flow process; cannot work in high-temperature conditions.
PI(Polymide)
easily bend； can work in high-temperature conditions.
more expensive than PET
Why Not Make All Circuit Boards Flexible?
Flexible circuit boards are certainly useful, but they are not going to replace rigid circuit boards for all applications. Cost efficiency is the main obstacle to implementing an exclusively flexible circuit board design in a consumer product. Rigid circuit boards are less expensive to manufacture and install in a typical automated high-volume fabricating facility.
Typically, the ideal solution for an innovative product is one that incorporates flexible circuitry when necessary and employs solid, reliable rigid circuit boards where possible to keep manufacturing and assembly costs down.
Some manufacturers even use hybrid rigid-flex printed circuit boards expressly for this purpose. This is common in laptop computers and medical devices, where rigid circuit boards can be connected to one other using ribbon-like flexible circuits. These boards can be compounded and designed to meet any number of engineering needs by focusing on the respective strengths of each circuit board base technology.
PCBWay creates both flexible and printed circuit boards for product manufacturers. Enjoy a consultation with one of our sales reps to find out if your product prototype design is best served by flexible or rigid circuit board types.
Check PCBWay Flex PCB manufacturing capabilities in the following table:
Item
Capability
Layer
1-12
Board thickness (without stiffener)
4-40 mil
Tolerance of single layer
±1.0 mil
Tolerance of double‐layer (≤12mil)
± 1.2 mil
Tolerance of multi‐layer (≤12mil)
± 1.2 mil
Tolerance of multi‐layer (12mil‐32mil)
±5%
Tolerance of board thickness (including PI stiffener)
This message here is only a suggestion supplement to the above content, and does not for trading operations such as orders. If you have any urgent questions or order issues, please contact your sales rep.
Conventional FR4 reinforcement is hot-pressed, not glued. If you want to glue, it should be OK. But can you say that some use glue and some do not according to the region
FR4 aluminum sheet steel sheet PI reinforcement are pressed up, if you must use glue, you can use glue, but it is easy to peel off the specified area with glue will be easy to peel
It is ok to glue the stiffener, but it is easy to peel the adhesive. You can upload the file and our professional engineer will double check it for you.
The FR4 reinforcement is all heat-pressed as a whole. Cannot be 50% hot pressed. What are your specific needs?You can upload the file and our professional engineer will double check it for you.If you have special requirements, you can organize it in the document and upload it together.
Hi, Can rigid-flex PCBs also withstand extreme temperatures (-200 to 400 degrees)? Or does this only apply to flex PCBs? If so, what is the operating temperature of Rigid-Flex PCBs?
Hi, If I want EMI shielding or adhesive should I add these to separate layers? How would you like me to create the documentation so it is clear to your engineers?
For double-layer flex board, the maximum size is 1200mm, the other side doesn't exceed 238mm, or the two sides don't exceed 480mm*480mm at the same time. The maximum size of four-layer flex board is 400*480mm. The minimum size is 2*2mm
Conventional FR4 reinforcement is hot-pressed, not glued. If you want to glue, it should be OK. But can you say that some use glue and some do not according to the region FR4 aluminum sheet steel sheet PI reinforcement are pressed up, if you must use glue, you can use glue, but it is easy to peel off the specified area with glue will be easy to peel
It is ok to glue the stiffener, but it is easy to peel the adhesive. You can upload the file and our professional engineer will double check it for you.
Thanks for the response, Continuing the question, Can the hot-pressed reinforcement only be hot-pressed for example 50% of the reinforcement?
The FR4 reinforcement is all heat-pressed as a whole. Cannot be 50% hot pressed. What are your specific needs?You can upload the file and our professional engineer will double check it for you.If you have special requirements, you can organize it in the document and upload it together.
about 438mm*1200mm
The operating temperature is -40 ℃ to 110 ℃,the Soldering temperature is 288 ℃
Please create a separate layer in the file and name it EMI shielding or adhesive,so our engineer will understand it
For double-layer flex board, the maximum size is 1200mm, the other side doesn't exceed 238mm, or the two sides don't exceed 480mm*480mm at the same time. The maximum size of four-layer flex board is 400*480mm. The minimum size is 2*2mm
like https://www.pcbway.com/img/images/newpcbway/stiffener_pic.jpg