1. **Summary of Content:** High concentration of film removal solution and extended film removal times can lead to issues during the PCB manufacturing process. Even after the anti-coating film has been removed, if the board remains immersed in a strong alkali solution for too long, some tin powder may adhere to the copper foil’s surface. Additionally, a thin layer of metal tin can form on the copper during etching, providing temporary corrosion protection.

2. **Issues:** This protective tin layer can prevent the copper from being fully cleaned, resulting in potential short circuits in the circuit.

3. **Recommendations:** To avoid these problems, it is crucial to strictly control the concentration, temperature, and time of the film removal solution. Additionally, use a plug-in rack to handle the film during the removal process, and ensure that the plates are not stacked or allowed to touch each other.



This revised version should be clearer and more concise while retaining the original meaning.

1. **Short Circuit Caused by PCB Running Tin**:

1. Improper operation in the de-filming solution tank causes tin running.

2. Stacking of de-filming boards causes tin running.

**Improvement Method**:

(1) High concentration of film removal solution and prolonged film removal time can result in tin powder adhering to the copper foil. This tin layer, though thin, protects the copper surface and resists corrosion, leading to incomplete copper removal and short circuits. Thus, controlling the concentration, temperature, and time of the film removal solution is crucial. Use a plug-in rack to insert the film and avoid stacking or contact between plates.

(2) If stripped plates are stacked before drying, tin between them can dissolve and attach to the copper foil, leading to a thin protective tin layer and subsequent short circuits.

2. **Short Circuit Caused by Poor PCB Etching**:

1. The quality of the etching solution parameters directly affects etching quality. Our company uses an alkaline etching solution with the following specifics:

1.1 **pH Value**: Maintain between 8.3 and 8.8. Low pH makes the solution viscous, white, and less corrosive, potentially causing side corrosion. Adjust pH with ammonia.

1.2 **Chloride Ion**: Control between 190~210g/L. Use etching salt, which consists of ammonium chloride, to regulate chloride ion content.

1.3 **Specific Gravity**: Control by monitoring copper ion content, ideally between 145 and 155g/L, and test hourly for stability.

1.4 **Temperature**: Maintain between 48~52°C. Higher temperatures cause ammonia volatilization, unstable pH, and can deform PVC etching machine components. Install an automatic thermostat to regulate temperature.

1.5 **Speed**: Adjust based on plate thickness. For stable parameters, consider an automatic feeder to maintain consistent etching liquid composition.

3. **Uneven Electroplating Layer Thickness**:

(1) For automatic production, adjust current density (1.5~2.0A/dm²) according to hole size and ensure consistent plating time. Use cathode and anode baffles and implement “plating edge strips” to reduce potential differences.

(2) For manual production, use double clamps for large plates to maintain current density consistency. Install a timing alarm to ensure uniform plating time and reduce potential differences.

4. **PCB Visible Micro Short Circuit**:

1. Micro short circuits can be caused by scratches on the Mylar film or glass of the exposure machine.

**Improvement Methods**:

(1) Scratched Mylar film can trap dust and form black or opaque lines that block light during exposure, causing short circuits. Replace or clean scratched Mylar film with absolute alcohol to maintain transparency and prevent opaque scratches.

(2) Scratched exposure plate glass can also form opaque lines that cause short circuits. Replace or clean scratched glass with a water-free cleaner to ensure transparency and prevent short circuits.

5. **Short Circuit of the Film**:

1. Thin anti-plating film layers can cause short circuits during electroplating if the plating layer exceeds the film thickness, especially with smaller line spacings.

2. Unevenly distributed board patterns during electroplating can lead to short circuits due to high potential forming a sandwich film.

**Improvement Methods**:

(1) Increase the anti-plating layer thickness by selecting a suitable dry film or applying wet film twice.

(2) For uneven patterns, reduce current density (1.0~1.5A) during electroplating. Short electroplating times can result in high current density in isolated areas, causing excessive coating height and short circuits. Adjust current density to balance coating thickness and avoid film short circuits.
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