Print the designed circuit board using transfer paper, ensuring the shiny side is facing you. Typically, print two circuit boards on one sheet. Select the one with the best printing quality.
2. **Cutting Copper Clad Laminate**
Utilize the photosensitive plate to create a complete process diagram of the circuit board. Copper clad laminate, which consists of a board coated with copper film on both sides, should be cut to match the circuit board size—avoid excess to conserve materials.
3. **Pretreatment of Copper Clad Laminate**
Polish the surface of the copper clad laminate with fine sandpaper to remove the oxide layer, ensuring that the carbon powder from the thermal transfer paper adheres effectively during the circuit board transfer. The polishing standard is a bright surface free from noticeable stains.
4. **Transferring the Circuit Board**
Trim the printed circuit board to an appropriate size and adhere it to the copper clad laminate. After alignment, place the laminate in the heat transfer machine, ensuring the transfer paper remains aligned. Generally, after 2-3 transfer cycles, the circuit board should be securely transferred onto the copper clad laminate. Preheat the heat transfer machine to a temperature between 160-200 degrees Celsius, and exercise caution during operation due to the high temperatures!
**Corrosion Circuit Board**
First, ensure that the printed circuit board is fully transferred. If there are areas lacking transfer, use a black oil-based pen for repairs before proceeding with corrosion. Once the exposed copper film is entirely corroded, remove the circuit board from the corrosive solution and clean it to complete the corrosion process. The corrosive solution consists of concentrated hydrochloric acid, concentrated hydrogen peroxide, and water in a 1:2:3 ratio. When preparing the solution, add water first, followed by the concentrated acids, taking care to avoid splashes on skin or clothing—wash immediately if contact occurs. Given the strong corrosive nature of these solutions, prioritize safety during operations!
**PCB Drilling**
To accommodate electronic components, drilling the circuit board is essential. Select different drill bits based on the thickness of the component pins. While drilling, firmly press the circuit board, ensuring the drill speed remains sufficiently high. Operators should be monitored closely during this process.
**Circuit Board Pretreatment**
After drilling, polish the circuit board with fine sandpaper to remove toner, then rinse it with water. Once dry, apply rosin to the circuit side. To expedite the solidification of the rosin, use a hot air blower; it should set within 2-3 minutes.
**Double-Sided Tin Plate/Immersion Gold Plate Production Process:**
Cutting —- Drilling —- Sinking Copper —- Line —- Picture Electric —- Etching —- Solder Mask —- Character —- Spray Tin (or Heavy Gold) —- Gong Edge —- V-Cut (some boards may not require this) —- Flying Test —- Vacuum Packaging.
**Production Process of Double-Sided Gold-Plated Plate:**
Cutting —- Drilling —- Sinking Copper —- Lines —- Pictures —- Gold Plating —- Etching —- Solder Mask —- Characters —- Gong Edge —- V-Cut —- Flying Test —- Vacuum Packaging.
**Multilayer Tin Plate/Immersion Gold Plate Production Process:**
Cutting —- Inner Layer —- Laminating —- Drilling —- Sinking Copper —- Lines —- Picture Electricity —- Etching —- Solder Mask —- Character —- Spray Tin (or Heavy Gold) —- Gong Edge —- V-Cut (some boards may not need this) —- Flying Test —- Vacuum Packaging.
**Multi-Layer Plate Gold Plate Production Process:**
Cutting —- Inner Layer —- Laminating —- Drilling —- Sinking Copper —- Lines —- Picture Electricity —- Gold Plating —- Etching —- Solder Mask —- Character —- Gong Edge —- V-Cut —- Flying Test —- Vacuum Packaging.
**Anatomy Process:**
1. Remove components from the original board.
2. Scan the original board to obtain a graphic file.
3. Grind the surface layer to access the intermediate layer.
4. Scan the intermediate layer for another graphic file.
5. Repeat steps 2-4 until all layers are processed.
6. Use specialized software to convert graphic files into electrical relationship files—PCB diagrams. If you have the right software, the designer needs to trace the graphics only once.
7. Conduct thorough checks to complete the design.
**Layout Editor**
Key details in layout design include:
**Single Panel:** This type is preferred for lower costs. Layout may require components or jumpers to bypass traces. If excessive, consider double panels.
**Double Panel:** This can be used with or without plated through holes (PTH). PTH boards are pricier and reserved for complex, dense circuits. Minimize wires on the component side for easier material access. In PTH boards, plated through holes serve solely for electrical connections, not component installation. For cost and reliability, limit the number of holes. Choosing between single-sided and double-sided requires considering the component surface area (C) relative to the total area of the PCB (S); a proper constant ratio aids installation. Note that “US” typically refers to one side’s area.
**Introduction**
The relationship between pad diameter and maximum wire width is critical when fabricating the circuit board, PCB, aluminum substrate, high-frequency board, etc.
**Relationship Between Typical Pad Diameter and Maximum Wire Width:**
– Pad Diameter (inch/Mil/mm) | Maximum Wire Width (inch/Mil/mm)
– 0.040 / 40 / 1.015 | 0.015 / 15 / 0.38
– 0.050 / 50 / 1.27 | 0.020 / 20 / 0.5
– 0.062 / 62 / 1.57 | 0.025 / 25 / 0.63
– 0.075 / 75 / 1.9 | 0.025 / 25 / 0.63
– 0.086 / 86 / 2.18 | 0.040 / 40 / 1.01
– 0.100 / 100 / 2.54 | 0.040 / 40 / 1.01
– 0.125 / 125 / 3.17 | 0.050 / 50 / 1.27
– 0.150 / 150 / 3.81 | 0.075 / 75 / 1.9
– 0.175 / 175 / 4.44 | 0.100 / 100 / 2.54
**Production Issues:**
During design checks, the following checklist encompasses all aspects related to the design cycle, noting special applications that may require additional items:
1) Has the circuit been analyzed? Are basic units utilized to smooth the signal?
2) Are short or isolated key leads permitted in the circuit?
3) Is shielding necessary, and is it effective?
4) Have basic grid graphics been fully utilized?
5) Is the printed board size optimized?
6) Are the selected wire widths and spacing maximized?
7) Is the optimal PCB pad and hole size employed?
8) Are photographic plates and sketches appropriate?
9) Is the use of jumper wires minimized? Do they traverse components and accessories?
10) Are letters visible post-assembly? Are their size and model correct?
11) To prevent blistering, is there a window on large copper foil areas?
12) Are tool positioning holes included?
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