What is the difference between ICT test fixtures and FCT? What materials are used for them?
2024-08-22 16:58
ICT test fixtures and FCT test fixtures are both categories of testing fixtures. Different test fixtures serve different testing functions. What are the functions of ICT and FCT tests, and how do they differ? Below, we will explain it in detail for you.
I. ICT Test Fixture:
1.It can quickly verify whether the assembled circuit board (PCB) on the device falls within our design specifications.
2.It can rapidly locate soldering defects, such as missing components, incorrect parts, open/short circuits, reversed polarity, solder bridges, and other issues.
3.It can print detailed information about the aforementioned faults and defects for maintenance personnel reference, effectively reducing their reliance on technical expertise. Even without understanding the product schematic, they can still perform repairs.
ICT is primarily suitable for:
Testing batches of boards (since each board type requires a corresponding fixture).
Boards with high added value or high fixed value.
FCT (Functional Test Fixture) primarily tests the functionality of products. Its main test subject is the PCBA circuit board. PCBA requires different fixtures to test its various performance metrics. The FCT test fixture focuses on testing the PCBA after power-on, including:
- Voltage, current, power, power factor
- Frequency, duty cycle
- Brightness/color, character recognition, voice recognition
- Temperature measurement, pressure measurement, motion control
- FLASH and EEPROM programming, among other test items.
The FCT desktop computer functional test fixture is a mechanical auxiliary device used during the semi-finished/finished product stage or production process. It tests specific procedures to verify whether the desktop computer meets the original designer's intentions. Functional test fixtures are applied to analog, digital, memory, RF, power supply circuits, and other forms, each requiring corresponding functional test fixtures.
The ICT test fixture primarily evaluates the performance of online components. Its purpose is to detect defects in the production process and identify faulty components. It tests semi-finished products, whereas the FCT test fixture focuses on functional testing of finished PCBA boards. The FCT fixture simulates the product's operating environment, places the product in a working state, and examines its various conditions to verify the functionality of the target board. Both ICT and FCT test fixtures are used in electronics production lines.
What materials are used for ICT test fixtures?
Many people are familiar with ICT test fixtures. While we all know that ICT test fixtures are primarily used for testing, many are unaware of the materials they are made of. To help everyone better understand and utilize ICT test fixtures, we will now introduce the materials commonly used in their construction.
The materials commonly selected for ICT test fixtures include acrylic (Plexiglas) and epoxy resin boards. Typically, the probe holes in these fixtures are larger than 1 mm, and the primary material for such fixtures is acrylic. The main reason for this is that acrylic is cost-effective. When drilling relatively soft holes, the thermal expansion and contraction of the probe sleeves must align with the holes. If issues arise, the transparent nature of the fixture makes it easy to identify problems.
However, acrylic tends to melt during drilling, which can easily break drill bits, especially when the aperture is smaller than 0.8 mm. For apertures smaller than 1 mm, epoxy resin boards are generally preferred, as they are less likely to break drill bits and offer excellent resistance and rigidity. Epoxy resin boards do not expand or contract, so if the aperture is imprecise, the probe sleeves may become loose and wobble within the holes.
Epoxy resin boards are not transparent, making it difficult to visually inspect issues within the fixture. Additionally, acrylic has a higher coefficient of thermal expansion compared to epoxy resin boards. If the testing density is high, epoxy resin boards are the better choice.
The above details the materials used for ICT test fixtures. In practice, the selection of materials and the precision of drilling play a critical role in the overall accuracy of the test fixture. Therefore, it is advisable to choose materials based on specific requirements rather than solely focusing on cost.
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