#### 1. PCBA Parameter Requirements:
– **Flux Density**: The flux used should be **90-BY820C-ZH0 (Baoyue)**, with a density of **0.815 ± 0.005 g/ml**. This ensures consistent flux application during soldering, crucial for achieving proper wetting and reducing defects.
– **Preheating Temperature**:
– **Single-panel boards**: Preheat at **900°C** for the first stage, and **1000°C** for the second stage.
– **Double-layer and multilayer boards**: Preheat at **1000°C** for the first stage, and **1100°C** for the second stage.
Preheating is essential to reduce thermal shock and ensure uniform temperature distribution across the PCB.
– **Soldering Temperature**:
– **Single-sided boards**: The optimal soldering temperature is **250°C**.
– **Double-layer and multilayer boards**: Soldering should be done at **245°C** to prevent overheating of the PCB layers while ensuring good solder joints.
Controlling soldering temperature is crucial for reliable electrical connections without damaging the components.
– **Soldering Time**: The recommended soldering time is **2-4 seconds**. This ensures sufficient heat is applied for proper solder joint formation without excessive thermal exposure, which could damage sensitive components.
#### 2. Quality Control and Inspection Requirements:
– **Testing Tools**:
– **Density Meter**: Used to verify the flux density, ensuring consistency across different batches.
– **Process Temperature Testing Equipment**: Measures the temperature profile during both preheating and soldering stages, ensuring compliance with the specified temperature ranges.
– **Welding Quality Inspection**:
– **Inspection Frequency**: Inspect **5 boards every hour** to monitor soldering quality and detect potential issues early. Regular inspections help maintain soldering consistency and prevent defects.
– **Record Keeping**:
– **Materials Tracking**: Maintain records of all materials used in the soldering process, such as the **solder manufacturer**, **flux**, **plate washer water**, **pine perfume** (if applicable), and **antioxidants**. This is essential for traceability, quality assurance, and resolving any potential material-related issues.
#### Conclusion:
By following the above parameters for soldering temperatures, preheating stages, flux density, and soldering time, along with implementing a rigorous inspection process, you can achieve high-quality PCBA solder joints with minimal defects. Additionally, maintaining detailed records of materials ensures traceability and effective quality control, which are critical for the long-term reliability of the assembled PCBs.
### 1. Frequency Check: Hourly, Control Chart Creation for Monitoring Poor Soldering
Perform frequency checks on a hourly basis, and create a control chart to monitor soldering quality using PPM (Parts Per Million) values. This will allow for real-time detection of poor soldering and enable prompt corrective actions.
### 2. Self-Check for Grounding Resistance Tester
#### (1) **Parameter Settings**
– Constant Current Output: 10A
– Output Voltage Frequency: 50Hz
– Test Duration: 5 seconds
– Analog Resistance: 0.15Ω
#### (2) **Testing Requirements**
Conduct a self-check at the start of every shift and maintain a record using the “Ground Resistance Tester Checklist.”
#### (3) **Calibration Procedure (Clearance Check)**
Using the 9611/13 Intelligent Automatic Ground Resistance Tester as an example:
– **Purpose**: Eliminate test line resistance and contact resistance errors.
– First, place the instrument in standby mode, and set the test time to “LLL”.
– Short-circuit the two test leads, press the “Start” button, and observe the measurement value.
– If the display reads “0.000”, calibration is complete.
– If not, press and hold the “Calibration” button for approximately 2 seconds to reset the value to “0.000”.
– Press “Stop” to complete the calibration.
**Note**: Ensure the preset is set to “LLL” for calibration to be effective.
#### (4) **Self-Inspection Procedure**
1. Connect the test leads to the ends of the analog calibration resistance (0.15Ω).
2. Press “Start” to run the test. The instrument should sound an alarm.
3. If no alarm occurs, all PCBs manufactured since the last inspection require rework.
**Note**: External power supply (adapter) is not involved in grounding resistance testing.
### 3. Self-Check for Withstand Voltage Tester
#### (1) **Parameter Settings (Production Process)**
– Voltage:
– Class I Equipment: AC 1500V
– Class II Equipment: AC 3500V
– Test Duration: 5 seconds
– Leakage Current:
– Class I Equipment: 0.1mA (L) to 10mA (H)
– Class II Equipment: 0.5mA (L) to 10mA (H)
#### (2) **Testing Requirements**
Perform a self-check at the beginning of each work shift, and record results in the “Hot Pressure Tester Checklist.”
#### (3) **Self-Inspection Procedure**
1. Connect a 330KΩ/36W analog resistance to both the ground wire and high-voltage output terminal of the withstand voltage tester. Start the tester, and the instrument should alarm.
2. Disconnect the ground wire and high-voltage terminal, then start the tester again. An alarm should sound.
3. If no alarm occurs, all PCBA products manufactured since the last inspection require rework.
### 4. Soldering Iron Temperature Check
Use a soldering iron temperature tester to monitor the temperature of the constant-temperature soldering iron. During the test, ensure there is a small amount of molten solder on the tip. If the temperature falls outside the acceptable range, adjust the temperature and wait for one minute before testing again. Calibration should be performed weekly, and records must be documented in the “Soldering Iron Inspection Record” form, which should be retained for six months.
### 5. Torque Meter Check
#### (1) **PCBA Inspection Method**
Place the torque meter on a tightened screw, turn it in the opposite direction, and measure the torque at which the screw begins to loosen.
#### (2) **Detection Frequency**
Operators in PCB factories must check the torque meter once a day before starting work. This ensures screws are tightened correctly, avoiding issues related to improper torque application.
