The PCBA test is typically conducted towards the end of the processing cycle and serves to verify the integrity of the PCBA product. The testing process must adhere strictly to regulations to enhance test accuracy, thereby improving the quality of shipments from the PCBA processing plant. The PCBA test primarily evaluates the product’s functionality, power calibration, lifespan, performance, and other relevant data. So, what equipment is necessary for testing? Currently, the main test fixtures used in the PCBA production line are categorized as follows:
Under normal circumstances, PCBA processing factories can perform the following tests:
1. ICT Test
This test primarily assesses PCB circuit boards and components. It has a relatively narrow application range and involves relatively expensive equipment, often used only for high-end products. Its functions mainly include checking the circuit’s on-off status, voltage and current values, fluctuation curves, amplitude, noise, and other related parameters.
2. FCT Test
1. After PCBA production is completed, it is essential to burn the program into the IC and then perform a functional simulation test on the finished product. This step, known as the FCT test, is crucial for detecting hardware and software issues promptly. Results are then fed back to customers for software optimization and hardware improvements. This test is indispensable for PCBA processing factories.
2. Under normal circumstances, PCBA processing factories conduct the following tests:
3. Fatigue Test
As the name suggests, the fatigue test evaluates the durability of the PCBA to determine how long the circuit board can endure use before failure. This test typically involves sampling from the same batch. After subjecting the samples to high-frequency and extended operation, the probability and proportion of failure are assessed. This data is then used to determine the fatigue ratio.
4. Aging Test
The aging test involves continuously powering the product for a fixed duration to observe any failures or malfunctions. Only after passing the aging test can the product be approved for mass production, ensuring strict product control.
5. Extreme Conditions Test
This PCBA test, though not commonly used, is primarily applied in military, off-road vehicles, special equipment, and other products exposed to harsh working conditions. The test includes assessing limits for temperature, humidity, drops, water splash, and vibration.
6. How is the PCBA cleaning inspection performed?
The inspection following PCBA cleaning is predominantly conducted through visual inspection. For high-reliability products, special testing equipment and standardized methods are necessary to measure cleanliness. Key criteria include ion pollution and surface insulation resistance.
7. Cleanliness Standards
(1) Ion Pollution Degree
There is no specific standard for ion pollution in current SMT chip processing plants. Typically, either the US military standard MIL28809 or the American Standards Association standard ANSI/J-001B is referenced.
(2) Surface Insulation Resistance (SIR)
Surface insulation resistance is usually measured using a comb circuit. This method is straightforward and quantifiable, offering high reliability, though it is complex to implement. The design of a comb circuit is required for measurement. The standard typically requires that the surface insulation resistance SIR ≥ 10^10 ohms.
8. How is the inspection after PCBA cleaning performed?
Inspection methods should align with the cleanliness requirements of the product. For products with special requirements, such as military, medical, or precision instruments, measuring instruments like an Omega (Ω) meter are used to assess Na ion contamination. Typically, a shape test piece is also used to measure surface insulation resistance.
9. The Omega (Ω) instrument evaluates cleanliness by immersing the PCBA in a clean standard solvent to dissolve ionic contamination from the surface. The equivalent sodium ion content in the solvent indicates the cleanliness of the test piece.
10. Cleanliness indexes can be assessed through visual inspection methods for standard products. This method involves using a 4x microscope to examine the PCB and components. The surface should be free of beads, flux residues, and other contaminants. Contaminants serve as the basis for judgment.
