What are the Differences in the Copying Methods of Double-Sided and Multi-Layer PCBs?

The practical execution of PCB replication is straightforward, involving the scanning of the target circuit board, documenting precise component positions, extracting components to establish a bill of materials (BOM) for material procurement. Subsequently, the empty board, along with the PCB file, is dispatched to the manufacturing facility for production. Upon completion of the PCB, the procured components are soldered onto it. The circuit board undergoes testing and debugging processes for validation.

Ⅰ. PCB Copying Steps

Acquire a PCB and meticulously record models, parameters, and positions of key components on paper, emphasizing details like diode and triode directions and IC notches. Utilize a digital camera to capture images of component locations, considering the increasing complexity of modern PCBs.

Extract tin from PAD holes and all components on the multi-layer board. After cleaning the PCB with alcohol, place it in a scanner. To enhance scanning clarity, increase scanned pixels slightly. Buff the top and bottom layers with wet gauze paper for a shiny copper film. Scan both layers in color using PHOTOSHOP, ensuring proper horizontal and vertical positioning.

Convert the second image to black and white, ensuring clear lines. Adjust contrast and brightness if needed, saving images as TOP.BMP and BOT.BMP in BMP format. Use PHOTOSHOP for any graphic repairs.

Transfer two levels in PROTEL from BMP files to their corresponding PROTEL format files, ensuring consistency in PAD and VIA positions. Repeat the third step if variations occur, emphasizing the patience required in PCB copying for quality matching.

Change the TOP layer's BMP to TOP.PCB, converting it to the SILK layer (yellow layer). Draw lines on the TOP layer, positioning devices according to the drawing. After drawing, delete the SILK layer and repeat until all layers are drawn.

Import TOP.PCB and BOT.PCB into PROTEL, merging them into a single image.

Print TOP LAYER and BOTTOM LAYER on transparencies in a 1:1 ratio using a laser printer. Place the film on the PCB, checking for errors. Upon confirmation, the PCB copying process is complete.

A duplicate of the original board is created, but it remains incomplete. Testing is essential to ensure the clone board's electronic performance matches that of the original, signifying successful completion.

Remarks: For boards with multiple layers, proper polishing to the inner layer is crucial, involving replication of the third through fifth processes. Graphic names may vary based on the number of layers. Double-sided boards are typically replicated, while extreme caution is advised for multi-layer copy boards due to potential alignment issues.

Ⅱ. Double-Sided Replication Procedure

Scan both upper and lower layers of the circuit board and save the resulting images as BMP files.

Initiate Quickpcb2005, and under "File," choose "Open Basemap" to open the scanned image. For improved visibility, insert a pad using PP, observe the line and route, and utilize PAGEUP to magnify the screen. Sketch the layout in a manner akin to a child's drawing, then click "Save" to generate a B2P file.

To access the color image of another layer, select "File" and "Open Basemap."

Reopen the previously saved B2P file by selecting "File" and "Open." The duplicated board appears overlayed on this image; it mirrors the original PCB with identical hole placements, yet the circuit connections differ. Disable lines and silkscreens revealing the top layer by choosing "Options" - "Layer Settings" to focus solely on multi-layer vias.

Vias on both the top and bottom layers align in the same positions. Trace the base layer once more, resembling the process from earlier years. Click "Save" to append the top and bottom layer data to the existing B2P file.

Choose "File" and "Export as PCB File." Obtain a PCB file incorporating two layers of data, allowing for further board modifications, schematic diagram reprinting, or direct submission to a PCB manufacturing facility for production.

Ⅲ. Multilayer Board Replication Approach

Copying a four-layer board involves utilizing two double-sided boards, while a six-layer board requires three double-sided boards. The complexity of numerous unseen internal layers can be daunting. How do we unveil the inner intricacies of a sophisticated multi-layer board? – Layered

Various layering methods exist, such as knife peeling and potion corrosion, but the risk of excessive layer division leading to data loss is inherent. Our experience has shown that sanding proves to be the most precise method.

Following the replication of the top and bottom layers of the PCB, sandpaper is commonly employed to eliminate the outer layer and expose the inner layer. The PCB is typically placed on a flat surface before applying the sandpaper, ensuring even rubbing (for smaller boards, the sandpaper can be laid flat, holding the PCB with one finger and rubbing it on the sandpaper). The objective is to achieve uniform grinding.

Once the silk screen and green oil are removed, the copper wire and copper skin should undergo thorough cleaning. Generally, wiping the Bluetooth board takes only a few minutes, while wiping the memory stick may require around ten minutes. The duration can vary based on strength and technique.

Currently, the most prevalent and cost-effective layering method involves grinding. Searching for an unused PCB is the initial step. Although technically straightforward, grinding the board can be somewhat monotonous. There's no need to fret about wearing down the board into your fingertips; it merely requires some effort.

During the PCB layout process, after completing the system layout, a careful review of the PCB diagram is essential to assess the reasonableness and optimal effectiveness of the system layout. This review typically involves examining the following aspects:

Confirming that the system layout ensures rational or ideal wiring, reliable operation, and circuit reliability. Understanding the signal direction, power, and ground network is crucial during the architectural phase.

Verifying if the dimensions of the printed board match the processing drawing, ensuring it meets PCB manufacturing conditions, and checking for any behavior marks. Proper consideration is required for positioning connections, often overlooked in many PCB layouts.

Evaluating the compatibility of elements in two- and three-dimensional space, particularly the real dimensions and height of the device during soldering layout-free components.

Examining the density, organization, and completeness of the component layout, considering the overall density, signal direction, type, and vulnerable areas.

Ensuring that the plug-in board can be easily inserted into the device and that frequently replaced components can be conveniently replaced and connected with ease and reliability.

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