PCB Technical - PCB copy board essential: PCB copy board process and steps

PCB(PrintedCircuitBoard), the Chinese name is printed circuit board, also known as printed circuit board, printed circuit board. It is an important electronic component, a support for electronic components, and a provider of electrical connections for electronic components. Because it is made by electronic printing, it is called a "printed" circuit board. PCB copy board, that is, under the premise that there are physical objects of electronic products and circuit boards, reverse analysis of the circuit boards by reverse research and development techniques, and the original product PCB files, bill of materials (BOM) files, and schematic files Perform a 1:1 restoration of technical documents and PCB silk screen production documents, and then use these technical documents and production documents to perform PCB manufacturing, component welding, flying probe testing, circuit board debugging, and complete the complete copy of the original circuit board template.

The concept of PCB copy board was originally born in the 1980s when reverse engineering began to emerge in the domestic academia. It was a brand new concept proposed by Longren PCB Studio, a reverse engineering technology research team originally established in China at that time. It has gone through nearly 30 years. Years of development, at present, PCB copy board has become a global industry serving the development of the global electronics industry and domestic core technology research, and various copy board companies at home and abroad have also blossomed everywhere. In recent years, the development of this industry and the various sensations it has caused in the field of science and technology have caused more and more people to pay attention to it, and more companies have entered the technology to dare to compete with international companies through their services. The age of contending. Especially in China's Jiangsu, Zhejiang and Guangdong areas, PCB copying is more popular, and a number of authoritative laboratories specializing in PCB copying technology have emerged, such as Longren PCB Studio, Century Core Technology, and Core Valley.

PCB copy board, currently in the industry is often referred to as circuit board copy board, circuit board clone, circuit board copy, PCB clone, PCB reverse design or PCB reverse research and development. Regarding the definition of PCB copy board, how much does the industry and academia have This kind of argument, but they are not complete. If we want to give an accurate definition of PCB copy board, we can learn from the authoritative PCB copy board laboratory in China: PCB copy board, that is, there are physical objects of electronic products and circuit boards. Under the premise of, use reverse research and development technology to reversely analyze the circuit board, and restore the original product's PCB files, bill of materials (BOM) files, schematic files and other technical files and PCB silk screen production files at 1:1. Then use these technical documents and production documents for PCB manufacturing, component welding, flying probe testing, circuit board debugging, and complete the complete copy of the original circuit board template. Since electronic products are composed of various types of circuit boards, the core control part performs work. Therefore, the use of a process of PCB copying can complete the extraction of a full set of technical data of any electronic product and the imitation and cloning of products.

Many people have misunderstood the concept of PCB copy board. In fact, with the continuous development and deepening of the copy board industry, today's PCB copy board concept has been extended to a wider range and is no longer limited to simple copying and cloning of circuit boards., It will also involve the secondary development of products and the research and development of new products. For example, through the analysis and discussion of existing product technical documents, design ideas, structural features, process technology, etc., it can provide feasibility analysis and competitive reference for the development and design of new products, and assist R&D and design units to follow up the latest updates in time Technological development trends, timely adjustment and improvement of product design plans, and research and development of the most competitive new products in the market. At the same time, the process of PCB copying can realize the rapid update, upgrade and secondary development of various types of electronic products through the extraction and partial modification of technical data files. Customers wish to optimize the design and board modification of the PCB, and on this basis, they can also add new functions to the product or redesign the functional features, so that products with new functions will be unveiled at the fastest speed and with a new attitude. Not only has its own intellectual property rights, but also won the first opportunity in the market, bringing double benefits to customers.

At present, when many PCB copy board design service companies are struggling to survive and pursue profits in the market, a few companies have begun to establish their position at a higher level and become the leader in the industry. Among them, the most successful and the largest, The strongest technical strength and the most comprehensive service are Longren PCB Studio, Century Core and other folk reverse R&D technical teams that first emerged in China. Their success proves that PCB copy board contains huge energy. This energy is not only for copy-board design service companies, but also for the entire electronic product market and the information technology industry, because objectively they promote the technical capabilities of Chinese companies and completely break down technical barriers.

The technical realization process of PCB copy board is simply to scan the circuit board to be copied, record the detailed component location, and then remove the components to make the bill of materials (BOM) and arrange the material purchase, and the empty board is The scanned picture is processed by the copy board software and restored to the PCB board drawing file, and then the PCB file is sent to the plate making factory to make the board. After the board is made, the purchased components are soldered to the made PCB board, and then the circuit board is tested And debugging.

The specific technical steps are as follows:

The first step is to get a PCB. First, record the model, parameters, and positions of all vital parts on the paper, especially the direction of the diode, the tertiary tube, and the direction of the IC gap. It is best to use a digital camera to take two photos of the location of the vital parts. The current PCB circuit boards are getting more and more advanced. Some of the diode transistors above are not noticed at all.

The second step is to remove all the components and remove the tin in the PAD hole. Clean the PCB with alcohol and put it into the scanner. When the scanner scans, you need to raise the scanned pixels slightly to get a clearer image. Then lightly polish the top and bottom layers with water gauze until the copper film is shiny, put them in the scanner, start PHOTOSHOP, and scan the two layers in separately in color. Note that the PCB must be placed horizontally and vertically in the scanner, otherwise the scanned image cannot be used.

The third step is to adjust the contrast, brightness and darkness of the canvas to make the part with copper film and the part without copper film have a strong contrast, then turn the second image into black and white, and check whether the lines are clear. If not, repeat this step. If it is clear, save the picture as black and white BMP format files TOP BMP and BOT BMP. If you find any problems with the graphics, you can also use PHOTOSHOP to repair and correct them.

The fourth step is to convert the two BMP format files to PROTEL format files, and transfer two layers in PROTEL. For example, the positions of PAD and VIA that have passed through the two layers basically coincide, indicating that the previous steps are well done. If If there is a deviation, repeat the third step. Therefore, PCB copying is a work that requires patience, because a small problem will affect the quality and the degree of matching after copying.

The fifth step is to convert the BMP of the TOP layer to TOP PCB. Pay attention to the conversion to the SILK layer, which is the yellow layer. Then you can trace the line on the TOP layer and place the device according to the drawing in the second step. Delete the SILK layer after drawing. Repeat until all the layers are drawn.

The sixth step is to import TOP PCB and BOT PCB in PROTEL and combine them into one picture and it will be OK.

The seventh step, use a laser printer to print TOP LAYER and BOTTOM LAYER on transparent film (1:1 ratio), put the film on that PCB, and compare whether there are errors. If they are correct, you are done. . A copy board that is the same as the original board was born, but this is only half done. It is also necessary to test whether the electronic technical performance of the copy board is the same as the original board. If it is the same, it is really done.

Remarks: If it is a multilayer board, you need to carefully polish to the inner layer, and repeat the copying steps from the third to the fifth step. Of course, the naming of the graphics is also different. It depends on the number of layers. Generally, double-sided copying requires It is much simpler than the multi-layer board, and the multi-layer copy board is prone to misalignment, so the multi-layer board copy board must be especially careful and careful (where the internal vias and non-vias are prone to problems).

Double-sided copy board method:

1. Scan the upper and lower layers of the circuit board and save two BMP pictures.

2. Open the copy board software Quickpcb2005, click "File" "Open Base Map" to open a scanned picture. Use PAGEUP to zoom in on the screen, see the pad, press PP to place a pad, see the line and follow the PT to route... Just like a child drawing, draw it in this software, click "save" to generate a B2P file.

3. Click "File" and "Open Base Image" to open another layer of scanned color image;

4. Click "File" and "Open" again to open the B2P file saved earlier. We see the newly copied board, stacked on top of this picture-the same PCB board, the holes are in the same position, but the wiring connections are different . So we press "Options"-"Layer Settings", turn off the top-level circuit and silk screen here, leaving only multi-layer vias.

5. The vias on the top layer are in the same position as the vias on the bottom picture. Now we can trace the lines on the bottom layer as we did in childhood. Click "Save" again-the B2P file now has two layers of information on the top and bottom layers.

6. Click "File" and "Export as PCB File", you can get a PCB file with two layers of data, and you can change the board or output the schematic diagram or send it directly to the PCB plate factory for production

Multilayer board copy method:

In fact, the four-layer board copying is repeated copying two double-sided boards, and the sixth layer is repeated copying three double-sided boards... The reason why the multi-layer board is daunting is because we cannot see the internal wiring. How do we see the inner layers of a precision multilayer board?

-Layering.

There are many methods of layering, such as potion corrosion, tool stripping, etc., but it is easy to separate the layers and lose data. Experience tells us that sandpaper polishing is the most accurate.

When we finish copying the top and bottom layers of the PCB, we usually use sandpaper to polish the surface layer to show the inner layer; sandpaper is ordinary sandpaper sold in hardware stores, generally flat PCB, and then hold the sandpaper and rub evenly on the PCB (If the board is small, you can also flatten the sandpaper, and rub the sandpaper while pressing the PCB with one finger). The main point is to pave it flat so that it can be ground evenly.

The silk screen and green oil are generally wiped off, and the copper wire and copper skin should be wiped a few times. Generally speaking, the Bluetooth board can be wiped in a few minutes, and the memory stick will take about ten minutes; of course, if you have more energy, it will take less time; if you have less energy, it will take more time.

Grinding board is currently the most common solution used for layering, and it is also the most economical. We can find a discarded PCB and try it. In fact, grinding the board is not technically difficult, but it is a bit boring.

related information--

In addition to the simple concept of copying the circuit board, the PCB copy board also includes the decryption of some encrypted chips on the board, the reverse push of the PCB schematic diagram, and the production of the BOM list.

Anyone who has a certain understanding of PCB copying knows that chip decryption is an important part of the copying process, because the entire circuit board is to be copied, of course, including the various components on the board. PCB copy board itself is not a high-tech, the most difficult is the process of program disassembly, technical file reverse push and so on. At present, the most powerful and influential piece of chip decryption should be a few centuries-core, Loongson Century and other private technology research units. Now the SCM process models they can complete are summarized as follows: FREESCALE/MOTOLORA (Freescale/Motorola) ST (STMicroelectronics) MICROCHIP HOLTEK (Hetai) ELAN (Yilong) MICON (Mikeken MDT) FEELING (Yuanxiang) SONIX (Song Han) Zhongying Hitachi Mitsubishi (Renesas) Fujitsu ZILOG LG/HYUNDAI (Hyundai) ALTERA (Altera) LATTICE (Lattice) XILINX INTEL (Intel) ATMEL (Atmel) PHILIPS (Philips) ) Infineon SST STC (Hongjing) WINBOND ISSI SYNCMOS DALLAS CYPRESS (Cypress) Macronix other PLD/CPLD/AVR/51 series/FPGA IC series, there are many models, please consult relevant technical personnel for details.

Reversal of PCB schematic

The schematic diagram is a drawing composed of electrical symbols used to analyze the principle of the circuit. It plays an indispensable role in the process of product debugging, maintenance, and improvement. The reverse design of the schematic diagram is the opposite of the forward design. The forward design is the design of the schematic first, and then the PCB design based on the schematic. The reverse design of the PCB refers to the reverse deduction of the product based on the existing PCB file or the actual PCB. Schematic diagram to facilitate the technical analysis of the product and to assist the later product prototype debugging production or improvement and upgrade.

BOM list production

In the process of product reverse technology research and imitation development, the production of the BOM list and the placement map, and the production of the component coordinate map for the SMT placement machine are all necessary for later model welding, placement processing, complete prototype design and assembly production. Link.

BOM (Bill of Materials) is the basis for the purchase of device materials. It records various components, modules and other special materials required for product composition. The most important thing in the preparation of the BOM list is to require accurate measurement of various parameters of the components, because if the device parameters are wrong, it may affect the judgment of the device and the accuracy of material procurement, and may even lead to the failure of project development.

PCB change board

PCB board modification is a related concept in PCB copy board. It refers to the circuit adjustment or re-layout of the extracted PCB file to realize the functional modification of the original circuit board, which can quickly realize the update and upgrade of the product to satisfy some customers. Individual needs and special application requirements.