PCBA Manufacturing Test-printed
PCBA manufacturing test
The premise of PCBA manufacturing test is based on the concept that a defect free PCBA increases the chances of a functionally working board. Manufacturing test results strive to:
Pinpoint defects enabling efficient repairs to correct them. This is termed “defect isolation” and is a key contribution of Manufacturing test.
Provide data for quality improvements to the manufacturing process.
In most manufacturing practices, an additional functional test is performed after manufacturing test. The objective of the functional test is to ensure the board functions as it was designed and to provide additional defect coverage for those that were not covered by manufacturing test. The PCBA functional test defect universe is different from that of PCBA manufacturing test as is its test technologies. The PCBA functional test will determine whether the designed function performs as it was intended to. It may or may not isolate a failure to a particular component or connection. PCOLA/SOQ defect isolation is usually not indicative of proper PCBA function.
Generally the PCBA manufacturing test strategy complements electrical and imaging tests; minimizing redundant tests while increasing capability to detect a larger portion of the defect universe.
Electrical process test systems can be categorized into:
Manufacturing Defect Analyzer (MDA)
In-Circuit Test (ICT)
IEEE 1149.1 Boundary Scan and other DFT-oriented standards
Test systems in each of the categories vary in test methodology and within each category there can be differences in each system’s test capability and throughput.
Imaging systems typically used in PCBA manufacturing are:
Automated Optical Inspection (AOI)
Automated X-ray inspection (AXI)
These systems vary in the technology. AOI uses reflected light and cameras to capture images for analysis while AXI uses penetrating X-rays to inspect solder joint quality. AOI technology can be deployed at various stages of a surface mount technology (SMT) line to inspect solder paste deposition, component mounting and solder defects. X-rays can “see through” devices, for example, Ball-Grid Array devices, to inspect solder connections beneath them.