PCBA (Printed Circuit Board Assembly) manufacturers use a series of standards and metrics to ensure the quality and reliability of the final product when evaluating product quality and quality control. The following are some commonly used quality control indicators and acceptance criteria in PCBA processing:
One. Welding quality index:
1.Placement accuracy: The position of the component must be precisely aligned and not allowed to deviate from the center of the pad more than 1 4 of the size of the welded end of the component.
2.Solder Fillet Size: The solder joint should be of the appropriate size and shape to ensure full contact with the component pins and pads, and the solder penetration requirement is usually more than 75%.
3.Insufficient or excessive solder: The amount of solder paste on the solder joint should be just right, neither less than 1 4 of the solder end of the component (length, width, height), nor too much to cause a short circuit or affect electrical performance.
4.Tombstoning: The distance between the bottom solder surface of the component and the PCB pad should not exceed 05mm。
Solder balls: Solder balls with too large diameter are not allowed, and the diameter of solder balls is generally less than 01mm。
Two. Electrical Performance Test:
1.In-circuit test (ICT): Check whether the electrical connection of each solder joint and device is correct, and whether the resistance, capacitance, inductance value, transistor, integrated circuit and other parameters meet the design requirements.
2.Functional test: Simulate the actual use environment to verify whether the PCBA can perform all functions as designed.
Three. Visual inspection:
Visual inspection** includes, but is not limited to, solder joint gloss, color, surface defects (e.g., cracks, pinholes), label clarity, correct polarity orientation of components, etc.
Four. Mechanical Strength:
Solder joint strength: Confirm the mechanical stability of the solder joint by tensile test and other methods.
Five. Cleanliness & Protection:
1.Residue inspection: Make sure that there are no harmful residues on the PCBA surface, such as flux, rosin, etc.
2.Conformal coating coating: check whether the uniformity, thickness and coverage of conformal coating are up to standard.
Six. Certifications & Compliance:
It meets the requirements of IPC-A-610 and other industry standards, and obtains relevant ISO series (such as ISO 9001:2015 quality management system certification), RoHS WEEE environmental protection directive and other certifications.
Seven. Reliability Testing:
Temperature cycle test, humidity sensitivity test, vibration test, shock test, etc., to ensure that PCBA can maintain stable performance under various environmental conditions.
PCBA processing manufacturers will also formulate corresponding SPC (statistical process control) plans in combination with specific process flows, and use statistical tools such as CPK and PPM to monitor the stability and availability of the production process, so as to continuously optimize production quality.