A PCB is a printed circuit board that contains one or more rigid regions and one or more flex regions on a printed circuit board. It can be divided into a flexible layer with reinforced layer and rigid-flex joint multilayer pcb, and other different types.
8 Layers rigid flex PCB stack up
As the saying goes: “to be good at work, we must first of its good material,” so consider a combination of rigid flexible board design and production process, well prepared is very important, but it requires some expertise and The understanding of the required material properties, rigid flex combination of materials used in the direct impact of the subsequent production process and its performance.
In this case,Flexible board of copper materials Our use of DuPont (AP no adhesive series) flexible substrate polyimide, polyimide is a kind of good flexibility, excellent electrical properties and heat resisting property material, but it has a large hygroscopicity and impatience strong alkaline.
The reason why the choice of non-adhesive layer of the substrate, because the dielectric layer and the adhesive between the copper foil for acrylic, polyester, modified epoxy resin and other materials, which modified epoxy resin adhesive Although the polyester adhesive is excellent in heat resistance, dielectric properties, and flexibility, it is poor in heat resistance, although the polyester adhesive is satisfactory.
Glass transition temperature (Tg) and the pressure of the high temperature (185 ℃), is also a lot of factories using Japanese (epoxy series) of the substrate and adhesive to produce soft and hard combination plate.
The choice of rigid area also has certain requirements, we first select the lower cost of epoxy glue wood, because the surface is too smooth can not stick, and then choose to use FR-4.G200 have a certain thickness of the substrate etching Copper, but the end of the FR-4.G200 core material and PI resin system is different, Tg, CTE are not with the thermal shock after the rigid-flex joint warpage seriously can not meet the requirements, so the final selection of PI resin series of rigid materials ,Can useP95 substrate laminated, can also be used solely P95 prepreg pressure synthesis, so that the resin system with the rigid-flex plate pressed, you can avoid thermal shock after the warpage.
At present, there are more substrate manufacturers specifically for the development of hard and soft board and the production of a number of rigid plate material.
The adhesive part between the flex plate and the rigid plate is preferably press-bonded with a No flow (Low Flow) Prepreg because the fluidity of the adhesive is very helpful to the hard and soft transition region and does not cause There are a lot of raw materials enterprises have developed the PP chip and there are many kinds of specifications to meet the structural requirements, the other for customers in the ROHS, High Tg , Impedance, etc. also need to pay attention to whether the characteristics of raw material indicators to achieve the final requirements, such as the thickness of the material specifications, dielectric constant, TG value, environmental requirements.
Browse our website for more information about Andwin’s Rigid flex PCB.
By Andwin TechTeam