Calculation method to solution concentration In the PCB manufacturing

In PCB manufacturing technology, all kinds of solution play a key role on the final PCB product quality .Whether buying or accessory must be with scientific calculation.Based on the characteristics of PCB production, we provide six kind of calculation method for the colleague to choose:

1.Volume percentage concentration calculation:
Defined: 
volume ratio between Solute (or concentrated solution) and the solvent.
1:5 is sulfuric acid compound with one volume Concentrated sulfuric acid and water .

2.G l concentration calculation:
Defined: Grams of solute in the liter solution.
E.g.：100 grams of copper sulfate was dissolved into 10 liter water. How much is a liter of concentration？
100/10=10 G/L

3.The weight percentage concentration calculation
Defined: showed by the solute weight percentage of the total solution
E.g.：What’s the percentage , 3 grams of sodium carbonate was dissolved into 100 g water ?

4.The molar concentration calculation
Defined: showed by mole fraction of 1 molar enthalpy in 1 liter solution.
Symbol: M, n solute the mole fraction, V is the volume of a solution

5.Equivalent concentration calculation
Defined: A litre of solution contained in the number of gram equivalent of the solute. 
Symbol: N (gram equivalent/l).

6.The proportion of computing
Defined: All objects per unit volume weight (unit: g/cm 3).
Method: the hydrometer
Baume degree and the proportion of conversion methods:
Baume degree = 144.3 (144.3 / share); B = 144.3 / (144.3 - baume degree)

Circuit board design steps

The design of the circuit principle diagram：schematic drawing tools and all kinds of editing are necessary to get a correct and fine circuit principle diagram.
A network table:Network table is a bridge between
circuit design schematic diagram (SCH) and printed circuit board (PCB) design and it is the soul of the circuit board automatically.Network table can be obtained from the circuit principle diagram,and it can also be obtained from the printed circuit board.
The design of the printed circuit board:The design of the printed circuit board is mainly for PCB.In the process, we use the PCB design software to provide the power of implementation circuit board layout,and to complete tough job.

Draw up the simple circuit diagram.

1)After design drawing size PCB/Sch,Firstly we need to design part drawing,then to design drawing size.Drawing size is confirmed according to the scale and complexity of the circuit diagram.Setting the appropriate drawing size is the first step to design schematic diagram.

2)Set up the PCB/Sch design environment.That is including set lattice sizes and types、and the cursor type, etc.Most of the parameters can also use the system default values.

3)Rotating parts.User takes the parts from the parts library,according to the need of the circuit diagram,then  place them on drawings.He also defined even set the serial number and packaging of parts .

4)Wiring according to the schematic .We need to connect components in the drawings with electric wires and symbols,Using a variety of tools provided by the PCB/Sch.Then we can constitute a complete schematic diagram .

Matters needing attention:

A circuit board via brings about 10 pf capacitance effect,which introduce too much interference,for the high frequency circuit.So we should try to reduce the number hole when we are wiring.On the other hand,too much hole will lower circuit board
mechanical strength.

Working principle of PCB circuit board

一 Circuit board principle--brief introduction

printed circuit board，Also known as pcb board, Aluminum substrate, High-frequency plate, Printed circuit board (copper etching technology). It is an important electronic component, support for electronic components, and the provider for electronic component circuit connection. The traditional printed circuit board, using photo resist etching method, make circuit lines and surface, so it is called a printed circuit board or printed circuit board. Because of the continuous refinement with electronic products , most of the circuit board is attached by etching resist (lamination or coating) at present , after exposure post development, and then etching circuit board.

二 Circuit board principle--structure

The circuit board is mainly composed of a pad, hole, mounting holes, wires, connectors, electrical components, filling, boundary etc. Common board structures include single layer, double layer and multilayer. The main functions of each component are as follows:

Pad—Metal hole for welding component pin
Through hole—including metal via non metal vias, wherein the metal hole for connection between each layer components pin。
Mounting hole—Fixed circuit board
Wireway—Electrical network copper film connecting component pins
Connector—Component for connection between circuit boards
Electrical boundary—Used to determine the size of the circuit board，All components on the circuit board should not exceed the boundary。

三 Circuit board principle

Working principle of circuit board：utilizing the base plate insulating material separated from the surface of the conductive layer of copper foil, to make the electric current along the preset route flow in various components such as power, amplification, attenuation, modulation, demodulation, encoding function etc.

Expand knowledge:

The basic design process of circuit board:

* Circuit schematic design
* Generate network report
* Printed circuit board design
* Generate The printed circuit board table

Regulated power supply

1.3 ~ 25 V voltage adjustable voltage circuit diagram
The regulated power supply adjustable range is adjusted between 3.5 V ~ 25 V.Output current is big.And uses the adjustable voltage regulator tube circuit.Thus satisfied with the stable output voltage.
Working principle:
After rectifying filtering the dc voltage is provided by R1 to adjust the tube base and make adjust tube conduction.In V1 turn-on voltage through the RP,R2 make V2 open,Then the V3 open.Then V1, V2, V3 emitter and the collector voltage no longer change(Its role as regulator tube completely).Adjust the RP,Steady output voltage can be obtained.R1, RP, R2 and R3 ratio decide circuit output voltage value.
Component selection:
Transformer T choose 80W～100W,input AC220V.Output double winding AC28V.FU1 chooses 1A,FU2 chooses 3A-5A.VD1 VD2 choose 6A02.The RP chooses about 1w ordinary potentiometer.Resistance value is 250K-330K.C1 chooses 3300uF/35V electrolytic capacitor, C2, C3 choose 0.1uF monolithic capacitors, C4 chooses 470uF/35V electrolytic capacitor.R1 chooses 180-220Ω / 0.1W ~ 1 W, R2, R4, R5 choose 10 k Ω, 1/8 W.V1 choose 2N3055 ,V2 chooses 3DG180 or2SC3953, V3 chooses 3CG12 or3CG80.

Introduction to the development and application prospects of flexible circuit board

Abstract: with the upgrading of electronic products, FPC (flexible circuit board), owning its unique advantages ,cater to the electronic products development trend : lighter, thinner, shorter, smaller, which has played an important cornerstone in the field of electronic information industry . In this paper, through the analysis of FPC in practical applications, we analyzes the application of especially on the three areas like mobile phones, automotive, health care equipment of FPC ,to make a prospect of the development in the future.
Key words:FPC FPCA FPC,application ,Automotive electronics,Health care equipment,SMT,Mobile phone

Firstly,Summary of the flexible circuit board
Flexible Circuit board (Flexible Printed Circuit, FPC), also known as soft Circuit boards, Flexible Circuit board, or FPC soft board for short.With the advantages of high density of wiring, light weight, thin thickness, less wiring space limitations, high flexibility, etc.Completely accords with the development trend of electronic products ,lighter, thinner, shorter, smaller,which is the effective solution to satisfy the requirement of miniaturization of electronic products and mobile .FPC can be freely bended, coiled, folded, and can withstand millions of times dynamic bending ,without damage to the wire.Any arrangement in accordance with the spatial layout requirements is ok.It can arbitrarily move in three-dimensional space and scale, so as to achieve the effect of the integration components assembly and wire connection.FPC can greatly reduce the volume and weight of the electronic products,which match the electronic products needs of the development of high density, miniaturization, high reliability direction.Therefore, FPC is widely used in PC and peripheral products, automotive electronics, medical equipment, communication products and consumer electronics and other fields.
FPCA(Flexible Printed Circuit Assembly) is FPC components,FPC industry chain extension.One of the main techniques is the SMT industry.SMT(Surface Mount Technology)is electronic circuits Surface mount technology,SMT or surface mount technology.It is SMC/SMD for short, there can be no pin or wire surface components installed on the surface of printed circuit board assembly or other substrate surface.Through the reflow soldering or welding methods, it is welding assembly of electronic circuit technology.Application of SMT technology has the following advantages:
Firstly, it is with the high density for assembly electronic products,small volume, light weight.The volume and weight of the patch element is only about 1/10 of the traditional instrumentation components.After using SMT, electronic products is smaller by 40% ~ 60% in volume, 60% ~ 80% reduction in weight.Secondly, it own high reliability,strong the aseismic capability, low solder joint defect rate , good high frequency characteristics.Thirdly, it reduce the electromagnetic and radio frequency interference.Fourthly, it is easily to realize automation,and to improve production efficiency.Fifthly, that can save material, energy, equipment, manpower, time, etc.

Secondly, the application of the flexible circuit board
Electronic products, light, thin, short, small demand trend, turn to the FPC rapidly from civil, to consumer electronics.In recent years, a large number of the high-tech electronics are Emerged ,and mostly have been adopted the flexible circuit board. What does Japanese scholars say in "the high density flexible printed circuit board", is that almost all the internal of the electrical products have been brought in the flexible circuit board,and Now I'm afraid it's hard to find electronic products
without the use of the flexible circuit board .

Thirdly, the market prospect of the flexible circuit board.
With the advancement of informatization, intelligent building, the market demand for the flexible circuit board will be bigger and bigger.
(1)The mobile phone market.In terms of mobile phones, FPC exist mainly as the connection parts between folding part signal and rotating parts signal in the mobile phone .Now,the general mobile phone should be with more than 3 piece of FPC .As being light, thin, short, small ,high feature phones are in popular, which is driving the FPC demand.The ministry of industry and information technology released 2014 communication operators statistical bulletin shows,mobile phone users Net increase 56.98 million ,and the total is 1.286 billion.Mobile phone users universality rate reach 94.5 telephones/one hundred people.That is 3.7 telephones/one hundred people higher then the last year.2018 smartphone users index represents half of the global mobile phone users,which means that the feature phones will become the minority in the field of electronic communications.Smart phone FPC content is higher than that of general electronic products, using 5 ~ 12 pieces of FPC.That is Higher than that of feature phones 1 ~ 5,and Each smart phone FPC output value is about 2 ~ 3 times that of feature phones.Such a huge market will inevitably drive the rapid development of the related fields.Smartphones phase module, antenna, monitor, USB line cannot leave the figure of FPC.
(2) The car electronic market.Under the FPC trend of precision components,based on the three-dimensional structure of the car body while Wiring area is Narrow and bent,we Using FPC components can meet the design requirements more.
(3) The medical monitoring equipment.In the past ten years,China's medical equipment market Sales scale ,has been Increased from 17.9 billion yuan of 2001 to 212 billion yuan of 2013.That has increased by 11.84 times ,Eliminating price factors.With the rapid development of economy in our country,our government pay more attention to County, township, community and other grassroots medical and health system construction.Aging, two-child policy, consumption upgrade, the health investment, policy support and so on work together to promote Health care equipment to a sizable development space,based on the overall level of the domestic is remaining at low levels at present .The domestic medical equipment industry development prospects is worth looking forward to.

To sum up, along with the social demand for information, intelligent has been enhanced unceasingly,and Almost been penetrated into all walks of life.It is hard to find  slightly more complex electronics without the use of FPC and FPC components.As the country will further invest in various fields of electronic information construction,and the quickening pace will be in downstream areas of electronic information construction,the FPC and FPC components development must be drived up .

How to detect and repair circuit board?

Firstly, fault distribution
1, the incomplete statistics for circuit board fault :
The chip is damaged by 30%;Discrete component is damaged by 30%;copper wire (PCB) is fractured by 30%;Program is damaged or lost by 10% (rising).
2, By the known,if there is a problem with the program or influence in the fault PCB board when you don’t own a workable board ,then it has no possibility to repair,because we are not familiar with its attachment, neither the original program.

Secondly, the crystal oscillator
1,Usually, we can only use the oscilloscope (it need to plus electric for crystal vibration) or frequency meter to test,but Multimeter can not to measure.Otherwise, we can only use the substitution method.
2,Common faults of vibration:the internal leakage;Internal open;Metamorphic deviation;Peripheral connected capacitor leakage.The leakage phenomenon should be able to be measured by < tester > VI curve.
3,For the whole plate test ,we can use two methods of judgment:the chip around crystals is not through when we test it ;except the crystals ,we couldn't find the other point of failure.
4,There are two common crystals:with two feet ;with four feet.Notice:it is added the electric to the one with two feet,so do not casually short circuit.

Thirdly, function and parameter test
1,What the < tester > can show are cut-off area, enlarged area and saturated area,but can not test the concrete numerical value for Working frequency and speed.
2,In the same way,for TTL digital chips,We can only know that there are output changes of high and low level , but can not find out its the speed along which it rises or falls.

Fourthly, reset circuit
 1,When the fault circuit boards is with large scale integrated circuit, we should pay attention to reset problem.
2,Before the test ,it’s better to best it back to the device,and to turn on and off the machine again and again,to press the reset button more times.

Fifthly, the chip with program
1,An EPROM chip usually should not be damaged.The chip need ultraviolet light to wipe away the program, so it will not be damaged in the test procedure.But it is better to prepare backup to avoid damage because of idle for a long time .
2,EEPROM、SPROM and RAM chips with a battery are both easy to damage the program.It is not confirmed whether it can damage the program or not after scanning With the < tester > VI curve .But we’d better to be careful when we meet such situation.
3,For the chip with battery, please do not easily detach it from the circuit board .