Tom
11-03-2002, 11:47 AM
IPC Advanced Study Guide Page Reference: Page 44, Section 1.6
Essentially there are five basic types of automatic test and inspection techniques used to evaluate surface mount assemblies.
These are:
Automatic optical inspection
- Evaluates component position and orientation
Manufacturing defect analysis
- Checks the populated board for solder shorts
In-circuit test
- Operational verification of each individual component
- Evaluates process capability
Functional testing
- Operational verification of functional blocks of the circuit
Automatic X-ray Inspection
It is important to understand the sequence of events when assemblies are produced and when testing is performed. Some users want their boards conformally coated. The coating interferes with the opportunity to probe test points on the assembly to verify component functionality, thus the in-circuit test is performed prior to the application of the coating.
Since the application of conformal coating at times can impair the performance of the assembly, some high-speed circuits are tested functionally again, after the coating is applied. Thus, the connector area must be kept free. If the board does not function, the coating needs to be removed in order to repair, replace, or modify the circuit in any manner.
In-circuit test is usually performed using automatic in-circuit test equipment. A test land location for each common network in the circuit is matched to a test probe contact in the test fixture. The test system drives each device and can quickly locate defective devices or identify assembly problems.
Essentially there are five basic types of automatic test and inspection techniques used to evaluate surface mount assemblies.
These are:
Automatic optical inspection
- Evaluates component position and orientation
Manufacturing defect analysis
- Checks the populated board for solder shorts
In-circuit test
- Operational verification of each individual component
- Evaluates process capability
Functional testing
- Operational verification of functional blocks of the circuit
Automatic X-ray Inspection
It is important to understand the sequence of events when assemblies are produced and when testing is performed. Some users want their boards conformally coated. The coating interferes with the opportunity to probe test points on the assembly to verify component functionality, thus the in-circuit test is performed prior to the application of the coating.
Since the application of conformal coating at times can impair the performance of the assembly, some high-speed circuits are tested functionally again, after the coating is applied. Thus, the connector area must be kept free. If the board does not function, the coating needs to be removed in order to repair, replace, or modify the circuit in any manner.
In-circuit test is usually performed using automatic in-circuit test equipment. A test land location for each common network in the circuit is matched to a test probe contact in the test fixture. The test system drives each device and can quickly locate defective devices or identify assembly problems.