Copy Board

Copy board, also called cloning or generic, that is, to reverse design of pcb technology research; Also is to use copy someone else’s circuit board pcb software, also be in the circuit design software according to the people of the circuit board to draw a block and then yourself to do circuit board. This is the traditional to the explanation of the copy board along with the technical development, copy board copy board industry influence and range expanded, copy board are also constantly improve and extend the definition of, from the narrow sense, copy board only, the extraction of the reduction of electronic circuit board pcb file and use file for PCB cloning process; Broadly speaking, copy board includes not only the PCB file generic technology such as extraction, PCB cloning, PCB process, but also to modify PCB file (change), the electronic product shape mold 3 d data model and the extraction of generic (copy), all kinds of electronic components on printed circuit boards of electronic products to copy, encrypted chips on the PCB or decryption, single-chip system software for the disassembly of electronic products electronic products such as a full set of all technical process of cloning.

For PCB copy board , a lot of people do not understand , in the end what is the PCB copy board , and some people even think that a cottage PCB copy board . Cottage in everyone’s understanding, is meant to imitate , but definitely not imitate PCB copy board , PCB copy board ’s purpose is to learn the latest foreign electronic circuit design techniques , and then absorb the outstanding design, and then used to develop better design products .

PCB copy board is a kind of reverse technology research, the reverse is through a series of technical studies to obtain an excellent electronic products PCB circuit design , and circuit schematics and BOM tables. With this reverse research methods , others take two or three years developed a product, we study through the PCB copy board reverse way , may only need a month to spend two or three others will be able to learn the results of research out , which for us in developing countries to catch up with the pace of the world has played a very important role in promoting . And reverse research and development of technology, but also on the development team who play a role in promoting technological breakthrough , reverse technology research to develop and constantly update the forward also led research techniques. Research studies between forward and reverse is because of this competition, so in recent years to the rapid development of electronic technology , electronic products, almost one year replacement once behind the rate of replacement of electronic products will become increasingly fast. Because PCB copy board lowered the threshold of electronic technology . PCB copy board to make more and more quickly embarked on the forefront of developing high-tech electronic technology, electronic technology research and developed together . The larger the team , the world of electronic technology in order to develop the more blocks.

Background

Eighties of last century, Western capitalist countries to develop science and technology, a variety of high-technology electronic products emerged. Such electronic products have been widely used. Product developers have their full range of technical solutions, a monopoly on technical solutions such products. Some companies even malicious product development to raise the price of its products have been greater profits. In such a monopoly environment, some companies try to break this monopoly, profit from, try to imitate these products, do the reverse of these high-tech products research and analysis, what we call the PCB copy board. PCB copy board industry have emerged.

Copy board technology implementation process

First, to get a PCB, the recording paper is good in the first model , the parameters , and the position of all components , especially a diode , triode direction , IC direction of the gap . The best two photos with a digital camera to shoot vitality position . Now bigger and senior pcb circuit boards and some do not pay attention at the diode transistor can not see .

The second step, to remove all the devices , and the PAD holes in the tin removed. The PCB clean with alcohol , and then placed in the scanner, scanner when scanning needs slightly increase the number of pixels in order to get a clearer picture . Then water the top and bottom layers of paper yarn slightly polished, shiny polished to a copper film , into the scanner , start PHOTOSHOP, two color ways were swept into . Note , PCB placed in the scanner must be smooth vertical and horizontal , otherwise the scanned images can not be used .

The third step is to adjust the contrast of the canvas , shading , so that some portion of the copper film and the copper film is no strong contrast , the second figure is then converted to black and white, check the line is clear, if not clear , repeat this step. If clear, the survival of black and white BMP format files TOP.BMP and BOT.BMP, if you find a problem with the graphics can also be used to repair and fix PHOTOSHOP .

The fourth step , the two file formats are BMP format files into PROTEL , transferred two in PROTEL , the basic position of the two coincide , such as over- PAD and VIA , indicating that the first few steps to do well, if deviation , repeat the third step. So pcb copy board is a great need patience to work, because a little problem will affect the degree of match quality and copy board post .

The fifth step , the TOP layer of BMP into TOP.PCB, pay attention to the conversion to the SILK layer , that layer is yellow , then you are in TOP layer scanning line is it, and place the device according to the second step of the drawing . After drawing the SILK layer deleted. Repeatedly drawn good to know all the layers.

The sixth step in PROTEL will TOP.PCB and BOT.PCB transferred , combined into a graph on OK.

The seventh step , using a laser printer TOP LAYER, BOTTOM LAYER were printed onto a transparent film ( 1:1 ratio ) , the film onto a piece of PCB, a comparison is wrong, if yes, you’re done .

One and the same as the original board copy board was born, but this is only half finished. Also tested electronic copy board technical performance tests and is not the same as the original board . If it really is as complete.

Note : If you are still carefully polished plywood to the inside of the inner layer , while the third to the fifth step of repeating copy board step , of course, the graphics naming is different, according to the number of layers , and generally double sided copy board to lot simpler than plywood , multi- copy board allowed prone position on the case , so be especially careful multilayer copy board and care (internal vias and vias are not very prone to problems ) . Dual- panel copy board method :

pcb copy board contact system reliability design

Specific processes and methods of operation of the copy board

The first step: preparation

Get a good board to see if there is high position components , if the first element bit number , component packaging , such as detailed records temperature values ​​. Before removing the components must first scan it again as a backup. After removing the remaining components are higher and some smaller SMD components , this time to the second scan , a recording image with a resolution of 600dpi proposed suitable. Before scanning must be removed dirt on the surface of the PCB to ensure that the IC on the PCB type and character clearly visible on the image after scanning.

Step two : Remove the Components and Production BOM table

Aligned with a small air gun heating element to be demolished , forceps allow the wind to blow away the tube . First split resistors, capacitors and then split , and finally demolished IC. And record whether the drop- off and counter components previously installed , ready to have a good should be preceded by the demolition of the form tag, packaging , models, numerical or other recording projects in component recording double-sided adhesive paste on the column , write after removing the lower number of elements attached to each of the bit number corresponding to the position of the device and then dismantling the bridge after all of the electricity measured value ( the value of some of the device itself will change under the influence of high temperatures , it should be in all after cooling device , and then measure , then the measured values ​​are more accurate ) , the measurement data is entered into the computer upon completion of the archive .

The third step: In addition to the surface Yuxi Qing

Borrow flux, the surface of the PCB components removed by suction-line remaining dross removed, according to the number of layers PCB soldering iron temperature will adjust well , because MLB is not easy and rapid cooling molten tin , it should be the electric iron temperature increase , but not too high so as not to burn out the ink . The board will remove the tin with water after the washer or dryer to clean water that day .

Step four: copy board software, real-time operating

After image scanning its surface as the top and bottom , respectively , to convert them into a variety of copy board software can recognize the base map , according to the first component package basemap do ( including small screen printing, pad size and positioning holes , etc. ) , will be doing all the components into their respective positions , adjust the character to the font , font size, and position consistent with the original plate, you can proceed.

With sandpaper to silk screen , ink and character PCB surface polished off to expose bright copper ( polishing pad has a very important trick - must be polished direction and the direction perpendicular to the scanner ) . Of course, there is another method is to use an alkaline liquid may be heated off the ink , but a longer time . Former typically use a more environmentally friendly approach and harmless . With clear and complete PCB base map was copied from an important prerequisite for good PCB board .

For a multi-layer PCB copy board order is from outside to inside . In an 8-layer as an example:

After the first take one and eight ink copy End , eight , and then worn one and eight of copper , then copy two and seven , then three and six , and finally copied the four , five on it . There is an error during the operation to pay attention to the scanned image with real plates , it should be treated as appropriate to the size and direction consistent with the real board . Ensure the correct size after start basemap PCB components individually adjust the position , make it completely coincides with the base map , so the next step is placed over the hole , trace copper wires and shop . In this process should pay attention to details such as the width of the pore size and the exposed copper plates and other parameters.

Step 5: Check

A perfect inspection methods will directly affect the quality of a PCB diagram , using image processing software , graphics software and PCB combined physical connection between the circuit can make a 100% accurate judgments. Impedance considerable impact on the frequency board , in the only case of physical PCB impedance tester can be used for testing or PCB slice , using optical microscopy to measure the copper layer thickness and spacing , in addition to the analysis of the dielectric substrate constant ( usually FR4, Teflon , RCC as a medium ) , so in order to guarantee PCB indicators consistent with the original plate .

How the circuit board PCB copy board

PCB copy board, is already there in the electronics and circuit board real premise, the use of technical means to reverse the board reverse analysis, the original product PCB files, BOM, schematics and other technical documents 1:1 restore operation, and then use these technical documents and files for PCB production system board, components, soldering, circuit board testing, complete copy of the original circuit template.

Tools / materials

Model
Scanners
Digital Cameras
Computer
Quickpcb (PROTEL99SE software)

Precautions

MLB needs to carefully polished to the inside of the inner layer, while repeating the third to the fifth step of the copy board stepGeneral than double sided copy board plywood simple, multi-copy board prone position not, so be especially careful when copying multilayer (where internal vias and vias are not very prone to problems)

Accuracy issues

For precision problems copy board , depends on two aspects , one is the accuracy of the software, one is the original image accuracy. All kinds of copy board , technical capacity on the accuracy of the copy board are not uniform , and some companies copy board technical ability, copy board accuracy is not high , but some copy board technical ability , copy board precision can reach 1mil less.

For software , it uses 32-bit precision floating-point representation can not say there is any accuracy limitations , so the most important thing depends on the accuracy of the original scanned image , an analogy Well, if a 100 -megapixel photo shoot washable 5- inch photos, but if we want it to wash it into a 20 -inch photos simply do not know , the truth is the same , so for very high precision requirements of the circuit board , the order to discover the very high precision PCB diagram , in should choose a higher DPI scan .

DPI is the meaning of the number of points per inch . Each distance between two points is 1000/DPI, ie the unit mil scanned images.

If the DPI is 400 , then the distance between two points on the image is 1000/400 = 2.5 mil, that is to say at this time accuracy is 2.5mil.

This is the most scientific basis , so some people say 1mil less accuracy can be achieved , it is a prerequisite . In fact, depending on the original copy board precision scanning accuracy.

In summary, the board set the DPI when scanning is necessary based on the actual board depending on the required accuracy , if the board as the phone line spacing accuracy in 1mil or less, then you need to scan the DPI should be set at more than 1000DPI . The scanner on the market are able to meet this condition.

The higher the DPI , the sharper the picture , the higher precision , but the drawback is the picture is too large, high hardware requirements , so be specific settings according to specific circumstances. For the general accuracy of the board generally use 400DPI on the good , the phone boards and the like can be set 1000DPI more.

Copy board software selection

Copy board software is good or bad depends mainly function is complete , it is best to do all the work can be copied board in the software , so that efficiency was high , including component placement support PROTEL99SE for the best, currently 99SE component library very rich , can be downloaded to the interconnect . This is very crucial thing, handmade copy board components by era has passed , as many as there are hundreds of BGP component package as many elements go hand- built components rely too costly .

For the circuit is stable and reliable , in the design of circuits generally have large pieces of copper and power or ground connection , thus reducing noise and interference circuit. So it comes to laying copper network problem, for complex circuit board , the shop there are a lot of copper is also a lot to be connected to isolation , then if not solve this problem , laying copper can not be achieved , so there must be Defining network to shop copper ( " connected to the same network , different network isolation " ) , simply put all of them will be filled with the copper is shorted . It is also a measure of the copy board software a critical issue .

After selecting fully functional software , in order to ensure perfect results , for double and multilayer board copy board , technically it should have a wealth of experience and technical skill . Because with a bunk or a multilayer PCB, holes in the same location , just different line connection , then wiring rules depicted in the original board copy board software, the board has been ferreted out of the top bunk of PCB files stacked in another layer on the scanned image , the overlap between the two vias , and then set the top line and the screen is not displayed , according to the position depicted another layer vias line , so that the exported file contains the PCB on both sides of the double panel information .

MLB Similarly, just need to delineate the surface after sanding with sandpaper PCB file Figure out the surface , so that the inner alignment rules exposed, and then with the same copy board software skills can be ferreted out the way .

Currently on the copy board software market is still the most commonly used PROTEL99SE, the other is quickpcb 2005 V3.0 and the various versions of the color copy board software.

Which , Protel99SE was originally used in EDA design software Windows9X/2000/NT operating system , using the design library management, can be networked design, with strong data exchange capabilities and openness and 3D simulation capabilities , is a 32-bit design software , you can complete the circuit schematic design, printed circuit board [ 1 ] design and design of programmable logic devices , etc., can be designed to 32 signal layers , 16 power - stratigraphic and 16 machined layer .

Quickpcb 2005 V3.0 software designers all operations in line with most operating practices, can improve the efficiency of the copy board largely relieve pain and detection of the operator. A one-time pass rate can also copy board further assured.

Features:

Place pads , holes, lines, arcs , vias, components , FILL, POLYGON, text ;

Each element attribute settings, grid settings ;

Automatic capture CTRL key element mesh with the center ;

SHIFT key to select , to select , cut, copy, delete , rotate, mirror and repeat function ;

32 layer setting function , zoom display.

Legal disputes

PCB copy board belongs to the category of reverse engineering , since the whole concept was born , it has been under extensive controversy , the method of reverse engineering plays a huge role in the development of the integrated circuit industry , the manufacturers all around the world adopt this ways to understand the development of the product to others , if such behavior is strictly prohibited , will have an impact on the progress of integrated circuit technology, so that countries in the legislation are considered exceptions under certain conditions, this kind of infringement. For teaching, analysis and evaluation of the layout-design concepts , techniques , or used in a circuit layout- design , logical structure , component configuration and copy layout designs and analysis on the basis of the evaluation results will be used in the layout of an original among the design and manufacture of integrated circuits accordingly , are not regarded as infringement . However, others simply copying the protected layout-design and production of integrated circuits to operate for the purpose of sale shall be considered infringement.

January 2007 Chinese Supreme People’s Court announced the " unfair competition on the trial of civil cases the use of certain issues of interpretation ," the provisions of its own trade secrets developed by reverse engineering or obtained , it is not recognized as relating to the Anti-Unfair Competition Law provisions of the acts of violation of trade secrets .

The judicial interpretation also provides reverse engineering refers to the product obtained from public sources demolition , surveying and mapping , analysis and other technical means to obtain technical information about the product. After the party is aware of improper means trade secrets of others so, on the grounds of reverse engineering to get a legitimate act of assertion , not supported.

The judicial interpretation since February 1, 2007 the formal implementation .

Many regular copy board of establishments are clearly defined , where the company ’s reverse engineering customers , there must be a legitimate source of design copyright statement in order to protect the legitimate interests of copyright holders original design and commitment to reverse the outcome of the main requirements of customers used for legitimate purposes of teaching , analysis, technical research. Meanwhile, reverse engineering is committed to the secondary development on the original product design ideas, analysis and data extraction circuit theory by adding a new design concept and function module in product design , rapid realization of innovative product upgrades and updates based on the original generation , power electronics industry to enhance overall competitiveness .

Copy board type

What products can copy board is about what type of problem areas and products involved in the copy board , in fact , can be copied on board electronics product type and there is no uniform answer, because different each copy board ’s technical strength , copy board involved field and type is different. But overall, with the upgrading of technical capabilities copy board industry as a whole , the scope of the field of copy board and involved in continuous expansion , such as the large orange box copy board has been able to carry out any electronic product cloned copy board . Detailed copy board type and technology consulting contact with these companies from industries , the copy board to achieve a typical electronic product types are:

Instrumentation:
High-frequency signal generator, power generator , low frequency signal generator , high- frequency signal generator, high-precision instrument copy board, digital pulse frequency meter , analog frequency meter, counter, spreading device , time measuring instruments , special counters, frequency standards , frequency calibration phase comparison device, network tester, network analysis of radar tester, microwave power amplifiers, microwave equipment, microwave attenuator, microwave filters, communication measuring instruments ...

Communication category :
PCB copy board PHS , GSM mobile phones , CDMA mobile phones, wireless module , GPS locator , cable set-top boxes , terrestrial set-top boxes , satellite broadcasting set-top boxes ...

Network categories:
Server motherboard , motherboard switches , wireless routers , eight video cards , VPN devices , wireless , Internet telephony , VOIP gateways, high-end computer motherboard cards, high-end fiber optic network switches motherboard network routers , wireless base stations and terminal products motherboard , SDHPCB copy board , DWDMPCB copy board , LAN SWITCH, ADSLPCB, high-end computing devices , fiber board, network routing copy board, driver board copy board, terminal products , network hard copy board , network cameras ...

Consumer Products :
MP4PCB copy board, digital learning machine , mobile hard disk box , multimedia hard disk player , portable DVD, game peripheral PCB copy board, PCB copy board multimedia electronics , home theater , car DVD, TVPCB, car control board , USB copy board , digital cameras PCB copy board.

Industrial Control :
Security monitoring equipment , industrial motherboard, motherboard , UPS, industrial power industrial board PCB copy board , Embroidery machine control panel, the image monitor, cutting control panel , SMT industrial control panels , machine control panels, inverters, industrial control switching power supply , industrial boiler conductivity controllers, industrial control microcontroller, electromagnetic heating control cabinet , General engraving machine.

Copy board case

If there is a four-layer board, components have been removed, clean the surface of the paint , we want it copied into a PCB document , proceed as follows:

1 , the top plate scan and save images from the name of top.jpg, then set the scan DPI can be set according to the different densities , if setting is 400DPI.

2 , scanning the bottom plate , save the picture , from the name of bottom.jpg

3, the middle layer of a coarse sandpaper out , leaking copper , get clean after the scan , from the name of mid1.jpg

4, the intermediate layer 2 with coarse sandpaper out , leaking copper , get clean after the scan , from the name of mid2.jpg

5 , where the each picture in PHOTOSHOP leveling (optional transfer pictures, images horizontally guarantee , so out of line look good, but it is easy to figure down multiple alignment) , the underlying figure suggested here do horizontal mirroring , so that the top base map is consistent with the direction of the upper and lower positioning holes consistent . Finally each figure are saved as BMP files, such as : top.bmp, bottom.bmp, mid1.bmp, mid2.bmp. Note here that do not need to crop the picture was just best to leave more affluent , basically as long as the picture leveling get away .

6, open color copy board software , from the main menu "File" - > "Open BMP file ", select top.bmp file open .

7 After setting the DPI, you can copy the top chart , the first layer of the election to the top , and then began to put components , vias, wire and so on.

8 , the top put all things finished, save the temporary file ( in both manual and help is available through a menu or to choose their own toolbar button ) , a name for the top-1.dpb ( among different time saved name suggestions from the different numbers of names , such as top-1.dpb, top-2.dpb, thus avoiding damage to the cause of computer failure last file , but also to restore the previous version of the file , reduce losses , this is a suggestion of personal hobby).

9 , close the current picture window ( note that you can only open a picture , do not open multiple images ) .

10 , from the main menu "File" - > "Open BMP file ", select the bottom of Figure bottom.bmp, then open the temporary file top-1.dpb, then find a good figure painting the top and bottom are not aligned background , press Ctrl A key combination , you put all the elements selected, press on the keyboard , down, left and right cursor keys or numeric keys 2,4,6,8 overall mobile , choose a few reference points and the corresponding points in background after the alignment , then you can choose the current layer to the bottom, the bottom line is to take the open , pad , padding , etc., if the top of the line blocking the bottom, how to do it ? Very simple, from the main menu "Options" select " layer color settings ", the hook off the top of the can, the same top-level screen can be turned off. After copied the bottom, save a temporary file for bottom-1.dpb, PCB files or saved as a bottom-1.pcb, then the file is already a two-tier alignment, bonding layer of the document .

11 , the same copy board process is the same as the middle layer , repeat steps 9 to 10 , the final output of the PCB document is four together , and exactly the same kind of PCB map.

Value

Some people have done such a hypothesis: If the laptop research needs two years after the study came out in a foreign country , we began to enter the study would take two years , so these two years we can sell abroad notebook. Thus, not only our own laptop abroad than four years later , and four years abroad notebook market share and brand in China has reached the point where indestructible .

However, if the reverse technology such as the use of PCB copy board , the laptop ’s inception , we can quickly keep up with new product research , and also for adding new features, new breakthroughs , so that we can short period of time has its own technological achievements to compete with the monopoly of foreign products , and quickly surpassed. In fact, this assumption goes to show the opportunities where PCB copy board . Currently, the industry leader in the entire PCB copy board large research companies such as Orange Box science and technology , has expanded the range of PCB copy board to medical equipment, communications devices, consumer electronics, industrial control , instrumentation, radio and television , automotive electronics , household electronic applications in electronics, security electronics , manufacturing equipment, etc. , I believe that people will seize opportunities through orange Box civil science and technology R & D technical team reverse service for electronic markets offer more new technologies, new products, foreign products made ​​a strong competitor .

In particular, PCB copy board value embodied in the following aspects:

From the Angle of enterprises

Cloning can help enterprise quickly upgrade, follow the latest trends. In the shortest time and lowest cost to complete product development. And now nearly perfect electronic cloning technology support, product quality is a strong guarantee.

Related Concepts

PCB copy board in addition to the simple notion of copying the board also includes a panel of some of the encrypted chip decryption, thrust reversers , BOM list making , PCB design, PCB schematic technical concepts .

PCB schematic diagram of the thrust reverser

Schematic symbols are used to analyze the electrical circuit schematic drawings , it is the product commissioning, maintenance, improvement process has an indispensable role. Schematic design of forward thrust reversers on the contrary, is it a forward design schematic design , and then according to the schematic PCB design , schematic and PCB reverse thrust is defined according to the existing PCB or PCB -kind reverse documents derived products schematics to facilitate the product of technical analysis and assisting the latter product prototype debugging production or improvement upgrades.

Production BOM list

Reverse technology research and product development process of imitation , BOM list of production and placement location map , SMT placement machine with components produced are late model graph welding, chip processing, and assembly of complete prototype design type of necessary production link.

BOM ( bill of materials ) is a device based on the procurement of materials , which documented a variety of product composition required components, modules , and other special materials. BOM list of the most important is to require the production of a variety of parameter measurements precise components , because if the wrong device parameters , it is possible to determine the impact on the accuracy of the device and material procurement , project development and may even lead to failure .

PCB to board

PCB to board PCB copy board is a related concept , which refers to the extraction of PCB file line adjustment or re- layout to achieve the functionality of the original circuit board modifications can quickly realize upgrading of products to meet some customers individual needs and specific application requirements .
PCB Design

In high-speed design, controlled impedance characteristic impedance circuit board and is one of the most important and widespread problem. First, look at the definition of the transmission line : transmission line consists of two conductors composed of a certain length , a conductor used to send a signal , and the other for receiving signals ( remember " loop " instead of "ground " concept ) . In a multilayer board , the lines are each part of a transmission line , as a reference plane adjacent to the second line or loop. A line a " good" is the key to make the transmission line characteristic impedance is maintained constant throughout the line .
Circuit boards become critical " controlled impedance board" is to make all the characteristic impedance of the line to meet a specified value , usually between 25 ohms and 70 ohms . In the multi-layer circuit boards , the good performance of the transmission line characteristic impedance of the key is that it remains constant in the entire line .

However , what is the characteristic impedance ? Understand the characteristic impedance of the easiest ways is to look at the signal transmission encountered something. When the microwave along a transmission having the same cross-section as shown in a transmission line is moved, which is similar to FIG . Assumed that the distal end of the stepped wave and a voltage V to this transmission line , such as the one volt battery is connected to the transmission line ( which is located between the transmission line and the loop ) , once connected , the signal voltage wave along the line speed of light spread , its speed is usually about 6 inches / nanosecond . Of course, this is really the signal transmission line and the voltage difference between the loops , which can be any point from the adjacent points of the transmission line and the circuit to be measured. Figure 2 is a schematic diagram of the voltage signal transmission .
Zen method is to " generating a signal" , then 6 inches / nanosecond propagation velocity along the transmission lines . The first 0.01 ns 0.06 inches forward , when the transmission line has a positive excess charge and the loop has excess negative charge, the charge difference between the two is maintained at 1 volt difference between the two conductors , and two conductors which form a capacitor .

0.01 in the next nanosecond , but also the period of 0.06 inches voltage transmission line from 0 to 1 volt adjustment , which must be added a number of positive charges to the transmission line , and add some negative charge to the receiving line . Every move 0.06 inches , must put more charge moves to the transmission line , and the more negative charge added to the circuit . Every 0.01 nanoseconds , the transmission line must be charged another paragraph , and then propagate the signal to start along this section . Charge from the front end of the battery cable , when moving along this line , give a continuous portion of the transmission line charging , thus forming the loop between the transmission line and the voltage difference of one volt . Advancing 0.01 per nanosecond , you get some of the charges (± Q) from the battery in a constant time interval (± t) flowing from the battery within a constant power (± Q) is a constant current. Negative current actually flowing into the circuit and a positive current flowing out of the same, but just in front of the wave alternating current signal through the upper and lower lines form a capacitor , the end of the cycle .

Industry Outlook