If you want to give an accurate definition of the PCB copy board, you can use the industry’s authoritative PCB copy board laboratory to say: PCB copy board, that is, under the replacement of physical products of electronic products and circuit boards, use reverse research and development technology. Reverse analysis of the circuit board, and integrate technical documents such as PCB files, bill of materials (BOM) files, schematic files, and PCB silkscreen production files into the product, and then use these technical files and production files to restore PCB board, component welding, flying probe test, circuit board debugging, complete the complete copy of the original circuit board prototype.
Because electronic products are composed of various types of circuit boards, the core control part works. Therefore, the use of a PCB copy board can complete the extraction of a full set of technical information for any electronic product, as well as the imitation and cloning of the product.
For PCBコピーボード, many people do not understand what exactly is PCB copy board, some people even think that PCB copy board is a cottage. The cottage is the meaning of imitation in everyone’s understanding, but the PCBコピーボード is definitely not imitation. The purpose of the PCB copy board is to learn the latest foreign electronic circuit design technology, and then absorb the excellent design scheme, and then use it to develop and design better The product.
PCB copy board is a kind of reverse research technology, which is to obtain a good PCB design circuit of electronic products through a series of reverse research techniques, as well as circuit schematic diagram and BOM table. Through this reverse research method, a product that others need to develop in two or three years, we can use the PCB copy board reverse research method to learn the results that others have spent two or three years. This has played a very important role in helping our developing countries to catch up with the world.
The development of reverse research technology also promotes the technological breakthroughs of those development teams. The vigorous development of reverse research technology also leads to the continuous update of forward research technology. The relationship between forward research and reverse research is because of this competitive relationship, so the development of electronic technology can change with each passing year. Electronic products are updated almost every year, and the speed of electronic products replacement will only increase. fast.
Because PCB copy board reduces the threshold of electronic technology. The PCB copy board has made more and more developing countries quickly move to the forefront of high-tech electronic technology and research electronic technology with developed countries. The larger this research team is, the more electronic technology in this world can develop.
Step 2 of PCB design：PCB copy board circuit board copy board preliminary work
1. Use the schematic design tool to draw the schematic diagram and generate the corresponding netlist. Of course, in some special cases, such as the circuit board is relatively simple, and already has a netlist, you can directly enter the PCB design system without the schematic design. In the PCB design system, you can directly take part packaging, manual Generate the netlist.
2. Manually change the network table Define the pads that are not on the schematic diagram of some components such as fixed pins to the network connected to it, and can be defined to ground or protected ground without any physical connection. Change the pin names of some devices that have inconsistent pin names in the schematic package and the PCB package library to the same as those in the PCB package library, especially diodes and transistors.
Step 2 of PCB design: Draw a package library of a non-standard device defined by yourself
It is recommended to put all the devices you draw into a dedicated design file for the PCB library you created.
PCB design step three: Set up the PCB design environment and draw the printed circuit board frame with hollow in the middle, etc.
1. The first step after entering the PCB copy system is to set the PCB design environment, including setting the grid size and type, cursor type, layout parameters, wiring parameters, and so on. Most of the parameters can use the system default values, and after these parameters are set, they are in line with personal habits and do not need to be modified later.
2. When planning a printed circuit board, it is mainly to determine the frame of the circuit board, including the size of the circuit board and so on. Place pads of appropriate size where you need to place the fixing holes. For 3mm screws, pads with an outer diameter of 6.5 ~ 8mm and an inner diameter of 3.2 ~ 3.5mm can be transferred from other boards or PCB izards for standard boards.
Note: Before drawing the circuit board ground frame, be sure to set the current layer as Keep Out layer, that is, the wiring layer is prohibited.
Step 4 of PCB design: After opening all the PCB copy board library files to be used, import the netlist file and modify the part package
This step is a very important part. The netlist is the soul of the automatic wiring of the PCB, and it is also the interface between the schematic design and the impression circuit board design. Only after the netlist is loaded can the circuit board wiring be performed.
In the process of schematic design, ERC inspection will not involve the packaging of parts. Therefore, the package of the part may be forgotten when designing the schematic diagram, and the package of the part may be modified or supplemented according to the design situation when the netlist is introduced.
Of course, you can manually generate the netlist directly in the PCB and specify the part package.
Step 5 of PCB design: arranging the position of the circuit board copy board component package, also known as part layout
Protel99 can perform automatic layout or manual layout. If you want to perform automatic layout, run “Auto Place” under “Tools”. With this command, you need to be patient. The key to wiring is layout. Most designers use manual layout. Select a component with the mouse, hold down the left mouse button, drag the component to its destination, release the left button, and fix the component. Protel99 adds some new skills in layout. New interactive layout options include automatic selection and automatic alignment. Use the automatic selection method to quickly collect similar packaged components, then rotate, expand and organize them into groups, and then move to the desired position on the board. When the simple layout is complete, use the automatic alignment to neatly expand or shrink a group of similarly packaged components.
Tip: During automatic selection, use Shift + X or Y and Ctrl + X or Y to expand and shrink the X and Y directions of the selected component.
Note: The layout of parts should be comprehensively considered from the aspects of mechanical structure heat dissipation, electromagnetic interference, and convenience of future wiring. First arrange the devices related to the mechanical size and lock them, then the large components and the core components of the circuit, and then the small peripheral components.
Step 6 of PCB copying: make appropriate adjustments according to the situation and lock all components
If space on the board allows, you can put some wiring area similar to the experimental board on the board. For large boards, add more fixing screw holes in the middle. There should also be fixing screw holes on the side of the board with heavy devices or larger stress devices such as connectors. If necessary, some test pads can be placed in the appropriate positions, preferably in the schematic diagram. Change the over-sized pad vias to large, and define the network of all fixed screw hole pads to ground or protective ground.
After viewing, use VIEW3D function to check the actual effect and save it.
Step 7 of PCB design: PCB layout rules setting
The wiring rules are the rules for setting the wiring (such as the use of layers, groups of line widths, via spacing, and topology of the wiring, etc.). They can be exported from other boards through the Design-Rules Menu and imported into this board. ) This step does not need to be set every time, it can be set once according to personal habits.
Selecting Design-Rules generally requires resetting the following:
1. Clearance Constraint of RouTIng Tag
It specifies the distance that must be kept between the routing pad vias of different networks on the board. Generally, the board can be set to 0.254mm, the empty board can be set to 0.3mm, and the denser patch board can be set to 0.2-0.22mm. Very few printing plate processing manufacturers have a production capacity of 0.1-0.15mm. You can set this value if they agree. Below 0.1mm is absolutely prohibited.
2, routing layer and direction (RouTIng Layers with RouTIng label)
Here you can set the routing layer used and the main routing direction of each layer. Please note that the single panel of the patch only uses the top layer, and the straight-through type single panel only uses the bottom layer, but the power layer of the multilayer board is not set here (you can use the top or bottom layer in the Design-Layer Stack Manager and use Add Plane, double-click with the left mouse button to set it, and click Delete after deleting this layer. The mechanical layer is not set here either (you can select the mechanical layer to be used in the Design-Mechanical Layer and choose whether it is available. Depending on whether it is displayed in single-layer display mode at the same time).
Mechanical layer 1 Generally used to draw the border of the board;
Mechanical layer 3 It is generally used for mechanical structures such as bars on the drawing board;
Mechanical layer 4 It is generally used for drawing rulers and annotations. You can use the PCB Wizard to export a board with a PCAT structure.
3.via shape (Routing Via Style of RouTIng label)
It specifies the inner and outer diameters of vias that are automatically generated during manual and automatic wiring. They are divided into minimum, maximum, and preferred values. The preferred value is the most important, and the same applies below.
4. Width Constraint of Routing label
It specifies the width of the trace during manual and automatic routing. The preference of the entire board range is generally 0.2-0.6mm, and some additional network or net class line width settings are added, such as ground, +5 volt power line, AC power input line, power output line, and power group. Wait. The network group can be defined in the Design-Netlist Manager in advance. The ground wire is generally 1mm wide, and the various power cables are generally 0.5-1mm wide. The relationship between the line width on the printed board and the current is approximately 1 mm per line. For the current of amps, please refer to relevant information. When the preferred value of the wire diameter is too large for the SMD pad to pass through during automatic routing, it will automatically reduce to a section of the trace between the minimum width and the width of the pad when entering the SMD pad. The line width constraint of the board has the lowest priority, that is, the line width constraint conditions of the network and network group are first met when wiring. The following figure is an example
5.Polygon Connect Style of Manufacturing tab
Relief Connect method is recommended. Conductor Width is 0.3-0.5mm 4 wires 45 or 90 degrees.
The rest of the items can generally use its original default value, and items such as the topology of the wiring, the spacing of the power supply layer, and the network length matching the connection shape can be set as required.
Select Tools-Preferences, and select “Push Obstacle” in the “Interactive Routing” section of the “Options” column (push other cables when encountering cables from different networks. Ignore Obstacle is “through” and “Avoid Obstacle” is blocking). Delete excess traces). The Tracks, Via, etc. in the Defaults column can also be changed. Generally you don’t need to touch them.