How to design a PCB( Printed Circuit Board ) ?

WDF-FPC-M-37,4 layer,wonderfulpcb.com

Initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the schematic diagram the component pin pads were laid out on the mylar and then traces were routed to connect the pads. Rub-on dry transfers of common component footprints increased efficiency. Traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout. To fabricate the board, the finished photomask was photolithographically reproduced onto a photoresist coated on the blank copper-clad boards.

Nowadays PCBs are designed with dedicated layout software, generally in the following steps:

1.Schematic capture through an electronic design automation (EDA) tool.

2.Card dimensions and template are decided based on required circuitry and case of the PCB.

3.The positions of the components and heat sinks are determined.

4.Layer stack of the PCB is decided, with one to tens of layers depending on complexity. Ground and power planes are decided. A power plane is the counterpart to a ground plane and behaves as an AC signal ground while providing DC power to the circuits mounted on the PCB. Signal interconnections are traced on signal planes. Signal planes can be on the outer as well as inner layers. For optimal EMI performance high frequency signals are routed in internal layers between power or ground planes.

5.Line impedance is determined using dielectric layer thickness, routing copper thickness and trace-width. Trace separation is also taken into account in case of differential signals. Microstrip, stripline or dual stripline can be used to route signals.

6.Components are placed. Thermal considerations and geometry are taken into account. Vias and lands are marked.

7.Signal traces are routed. Electronic design automation tools usually create clearances and connections in power and ground planes automatically.

8.Gerber files are generated for manufacturing.

For further detailes, please contact wonderful09@wonderfulpcb.com.

FPC assembly Pallets features

I would like to introduce the comparison between Magnetic reflow pallets and silica gel plate.

A. Stability: magnetic reflow pallet in magnetic state to even out the FPC, as the physical process,magnetic may increase or decrease according to request, don't change due to factors such astemperature, time, relatively stable.Silica gel plate adopt chemistry, will change under differenttemperature or Time or other condition, which lack of stability. Especially in the use of a certainperiod of time after a drop in viscosity, and not clean viscosity decreased during us, which cause FPC substrate deformation while crossing the reflow soldering and affect the welding quality.

B. Usage Life: magnetic reflow tray used in magnetic material and working principle of physicalprocess, are high temperature resistant material,As long as it's not  destroyed by man or at accident situation, it can be permanent online.  statecan use permanent damage and accidents.Silica gel plate in use process, USES the chemical process,Inuse process, it will be aging of due to silicone materials, including Japan's material, no more than1000 times return.The cost is very high.

C. Quality: magnetic reflow pallet at work on FPC insulating protection at the same time, FPC won’t be destroyed when workman pick up the FPC.Silica gel plate in use process to ensure the smooth ofFPC, has certain viscosity,and will stick to FPC, which will be difficulty for picking up FPC andmay cause FPC deformation.

Comparison between Magnetic reflow pallets and normal plateA.Quality: magnetic reflow pallet, because of FPC flat surface cause from the steel, reflowsoldering will be reduced during FPC flow, which can guarantee the stability of welding quality,reduce adverse.Ordinary tray can only be used with high temperature tape around the FPC, afterreflow soldering, which easy to cause deformation to the middle part of FPC, tin water to overflow, cause badwelding, which will affect the quality. At the same time, magneticReflow soldering tray can reduce some difficulty, like can avoid the high temperature stick to Flexible pcblead to hard FPC being picked up or flexible PCB deformation.

Cost: magnetic reflow soldering tray, convenient to use,  reduce prework workers, and the personto take off the tape after reflow soldering, at meanwhile, can reduce the use amount of the hightemperature tape. Investment is bigger at first time to magnetic reflow soldering tray, however, ithas cost advantage for mass production.

Several classification of flexible printed circuit board

At present, mainly has the single side, double side, multilayer flexible circuit and Flexible pcb just four.


(1) single flexible plate is the lowest cost, when the PCB for electrical demand is not high.When single wiring, should choose single flexible plate.It has a layer of chemical etching of conductive graphics, in the flexible conductive graphics layer on the surface of the insulating substrate for rolled copper foil.Insulating base material can be polyimide, polyethylene terephthalate, aromatic polyamide fiber resin and PVC.


(2) double flexible plate is on the two sides each have a layer of insulating base film etching made of conductive graphics.Metallized hole to both sides of the insulation materials connection form a conductive path, in order to meet the deflection design and use of the function.While covering film can protect the single and double wires and components placed.


(3) multilayer flexible plate is a level 3 or more layers of single sided or double sided laminated flexible circuit together, through the drill away L form hole metallization, electroplating, the formation of a conductive path between different layers.So, do not need to adopt the complex welding process.Multilayer circuit in higher reliability, better thermal conductivity and convenient assembly has huge function differences in performance.When designing the layout, assembly shall be taken into consideration, layer number and size of flexible influence each other.


(4) the traditional just flexible plate is made from rigid and flexible substrate has a choice of formation pressure together.Structure closely to metallization away L form electrical connection.If a PCB is, opposite element, just flexible plate is a good choice.But if all the components are on one side, selects the double flexible plate, and on the back of the laminated layer on FR4 reinforced material, will be more economic.


Hybrid structure is a kind of sandwich plate, flexible circuit conductive layer made of different metals.A eight layer plate using FR - 4 as inner layer medium, the use of polyimide as outer medium, out from three different direction of the main board, lead each wire made of different metals.Constantan alloy, copper and gold as independent lead, respectively.This kind of hybrid structure is mostly used in electrical signal conversion and is quite harsh relationship and performance of heat transformation of low temperature circumstances, is the only feasible solution.


Even through the design and how easy it is to evaluate the total cost, in order to achieve the best performance/cost ratio.

PCB, CCL application CQC authentication problem solving-（2）---Wonderful PCB (hk) Limited

7, application considerations of CQC standard sample production?
A: cQc application process, a lot of samples, such as single, double-sided and multilayer Rigid-flex pcb must be in accordance with the relevant standard production standard test pattern. , therefore, should read carefully the sample when making standard graphics shows that for the appearance of the sample size, drilling and welding plate diameter, width of wire spacing, especially the laminated lining graphical distribution of parameters such as pay special attention to, in order to reduce due to the improper understanding during sample preparation and the amount of time the sample error.

High PCB Design----Wonderful PCB (hk) Limited

Author: Jodie
In the field of telecommunications , the design is very complex , the transmission speed in the transmission of application data , voice and image of the
Has been far higher than 500Mbps, people in the communications field in pursuit of higher performance and faster to launch production

Goods, and the cost is not the first. They will use more board layers, sufficient power and ground planes, any problems that may arise in the high-speed signal lines will be implemented using discrete components match. They have
SI (signal integrity) and EMC (electromagnetic compatibility) experts to simulate and analyze the wiring before each
an internal design engineers follow strict design requirements. So the field of communication design engineers through
this design is often used excessive speed PCB board design strategy.

Home computer motherboard design area is the other extreme, the cost and effectiveness above all , the design
Teachers are always using the fastest, the best , highest-performance CPU chips, memory and graphics processing module technology
To form increasingly complex computer . The home computer motherboards are usually four shelves , some high-speed PCB

Design technology is difficult to apply to this area , so engineers in the field of home computers generally have adopted over
Research methods to design high-speed PCB board, they are designed to fully study the specific circumstances of those who truly resolved
The existence of high-speed circuit problem.

Wonderful Printed Flexible Circuit Board

Single-sided Flexible pcb is the lowest cost, less demanding on the electrical properties when the PCB. In the single-sided wiring, single-sided flexible board should be selected. Chemical etching of the layer which has a conductive pattern, the surface of the flexible insulating substrate a conductive pattern layer is rolled copper foil. An insulating base material may be polyimide, polyethylene terephthalate, polyvinyl acetate and aramid fiber.
   
Double-sided flexible board is on both sides of the insulating base film made ​​of each conductive pattern layer etching. Plated hole pattern on both sides of the insulating material to form a conductive path, to meet the deflection of the design and functionality. The cover film can protect the single, double wire and indicating element sited.
      
Multi-layer flexible plate is 3 or more layers on one side or double-sided flexible circuits laminated together through the drill larvae L, metal plating is formed holes in the conductive path is formed between the different layers. Thus, without the use of complex welding process. The multilayer circuit at a higher reliability, better thermal conductivity and more convenient assembly performance has great functional differences. In designing the layout, you should take into account the assembly dimensions, layers and flexible interaction.

Flex-rigid board is made of a rigid and flexible substrates are laminated together to form selectively. Compact structure, in order to form a conductive metal larvae L connection. If a PCB positive and negative both components, rigid flexible board is a good choice. However, if all of the components are on the side of the case, use double-sided flexible board and laminated on the back layer of reinforced FR4 material, will be more economical.
Sophie Deng
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