4. Convert the two BMP files to Protel format, ensuring they align with the two-tier pass and VIA locations. This indicates that the initial steps were successful. If deviations occur, please revisit step three. PCB copying requires great patience, as even minor issues can impact the quality and compatibility of the copied board.

5. Convert the top BMW to the top layer. Note that the PCB appears yellow, and then describe it on the top layer. Place the components as per step two. After completion, delete the SILK layer. Ensure that all layers are drawn accurately and repeatedly.

6. Transfer the Toppcb and BOT.PCB into a Protel image.

7. Use a laser printer to print the Top Layer and Bottom Layer onto transparent film at a 1:1 scale, then position the film on the PCB to check for errors. If everything matches, you are nearly done. A replica of the original board has been created, but testing the electronic performance of the replicated board against the original is still necessary. If they match, the process is complete.

Note: For multilayer boards, carefully grind the inner layers while repeating steps three to five. The naming of graphics should reflect the number of layers. Generally, double-sided boards are simpler to copy than multilayer ones, yet multilayer boards align more easily. Therefore, extra caution is warranted, especially with internal guide holes and non-guide holes, which are prone to issues.

**Double Panel Copy Method:**

1. Scan the two BMW images from the circuit board’s bottom surface.

2. Open the Quickpcb2005 software, load the base map, and the scanned image. Use Pageup to zoom in on the screen, align the pads as per PP, and view the lines according to PT, akin to a child’s drawing. Click “Save” to generate the B2P file.

3. Open the base image and load the second scanned layer.

4. Click File to open the previously saved B2P file. The copied board should align with this photo—the same PCB holes must match. While the lines may differ, close the top line and silk screen layers, keeping only the multilayer passage visible.

5. Ensure the top holes align with the bottom holes. Now, proceed to draw the bottom lines as if recalling childhood methods. At this point, the B2P file includes top and bottom information.

6. Export the file as a PCB file, yielding a two-layer data PCB that can be reassembled or sent to a PCB manufacturer for production.

**Three-Layer Board Copy Method:**

For four-layer boards, duplicate using two double-sided boards, and for six layers, use three double-sided boards. Layering can be challenging since internal wiring isn’t visible. Precision is crucial for multilayer boards—layering methods like chemical corrosion or peeling can lead to data loss. Experience suggests that sanding is the most accurate technique.

When copying the PCB bottom, sand the surface to expose the inner layer using standard sandpaper from hardware stores. Rub the PCB evenly against the sandpaper (for smaller boards, hold it with your fingers). The key is uniform pressure for even grinding.

Silk screen and green oil generally erase copper traces. Typically, you can wipe a Bluetooth board in about ten minutes; naturally, larger jobs will require less time. Sanding is the most common and cost-effective layering solution. Practicing on discarded PCBs is advisable; it’s not technically difficult but can be tedious.

Once the PCB layout is complete, review the PCB diagram for system layout rationality. Assessments should include:

1. Ensuring the layout optimizes circuit performance and reliability, while comprehensively understanding signal directions and power/ground networks.

2. Verifying the board’s dimensions match processing drawings, meeting PCB manufacturing requirements. Many PCB layouts prioritize aesthetics but may neglect precise component positioning, affecting circuit connectivity.

3. Checking for conflicts in two-dimensional and three-dimensional spaces, especially considering component heights. Non-layout parts generally should not exceed 3mm.

4. Confirming that components are arranged densely yet orderly. Consider both signal direction and layout density.

5. Ensuring ease of replacement for frequently serviced components, maintaining reliability for regular replacements and plug-ins.