Here are the details on how to inspect infrared touch PCBA (Printed Circuit Board Assemblies):

Outward appearance inspection

1. Component Integrity:

• First of all, observe whether all kinds of components on the PCB are complete, and whether there are any omissions or wrong pastes. For example, resistors, capacitors, chips, etc., are checked against the schematic and bill of materials (BOM) to ensure that the correct components are in place at each location.
• Check the pins of the components to see if there is any deformation and breakage, and for the chip components, the pins should be soldered flat on the pads.

2. Welding quality:

• Look at the appearance of the solder joints, high-quality solder joints should be smooth, rounded, and bright silver or golden yellow. There should be no defects such as porosity, cracks, and virtual welding on the surface. Virtual soldering is manifested as a solder joint that looks like a connection but the actual contact is poor, gently shaking the component, if the solder joint shows signs of loosening, it may be a virtual solder.
• Check the amount of solder, which can not cause too much short circuit of adjacent solder joints, nor too little to affect the reliability of electrical connections. Bridging is also a common problem, i.e. there should be no extra solder connections between adjacent solder joints.

Electrical performance testing

• On-off test:Use a professional multimeter, place the pen at both ends of the circuit node to be tested, set it as a resistance measurement file, and measure the resistance value between the two points. The normally conductive line resistance should be close to zero ohms, and if the resistance value is infinite, the line is open. This is very effective for checking PCB routing, plug-in connections, and solder joints for on.
• Voltage test:According to the circuit design requirements, connect the PCBA to the appropriate power supply, and then use the voltage level of the multimeter to measure the voltage value of the key node. For example, the voltage of the power supply pin of the chip should be within the range specified in the chip specification, if the voltage is abnormal, it may be caused by a power supply circuit failure, a voltage regulator chip problem, or a short circuit or open circuit.
• Signal Integrity Test:For high-speed digital circuits, equipment such as oscilloscopes are required to detect signal quality. Observe whether there are distortions, overshoots, undershoots, etc. in clock signals and data transmission signals. Overshoot and undershoot can damage components, and distorted signals can lead to data transmission errors that affect the proper function of the entire circuit.

Functional test

1. Unit Module Testing

• Divide the PCBA into different modules according to function, and test each module separately. For example, for a PCBA containing a Bluetooth module, turn on the Bluetooth function, use a mobile phone or other Bluetooth device to search and connect, and test whether the Bluetooth pairing, data transmission and other functions are normal.
• For those with audio processing modules, input audio signals, and listen to whether the output audio is clear and free of noise and whether the volume meets the requirements by connecting headphones or speakers.

2. Functional test of the whole machine:Set the humidity test chamber humidity, keep the PCBA in a high humidity environment (such as 90% RH) for a period of time, and check whether there are problems such as short circuit and corrosion caused by moisture. Especially for electronics used in humid areas or outdoors, humidity testing is crucial.

Environmental Suitability Test (optional but important)

• Temperature test:Put the PCBA into the high and low temperature test chamber, and set the test chamber temperature according to the ambient temperature range of the product. Hold it for a certain period of time in a high-temperature environment (such as 60°C or even higher, depending on the product) to observe whether the PCBA fails, such as component performance degradation, solder joint cracking, etc.; The same test is carried out in a low temperature environment (such as -20°C) to see if there is a cold start problem, abnormal LCD display and other phenomena.
• Humidity test:Set the humidity test chamber humidity, keep the PCBA in a high humidity environment (such as 90% RH) for a period of time, and check whether there are problems such as short circuit and corrosion caused by moisture. Especially for electronics used in humid areas or outdoors, humidity testing is crucial.
• Vibration test:Fix the PCBA on the shaking table, and conduct the vibration test according to the vibration frequency and amplitude that the product may encounter. This simulates vibration during transportation or actual use, detects whether there are loose components, solder joints fall off, etc., and ensures the reliability of the PCBA in a vibration environment.