In-circuit Tester (ICT) is a standard test method for checkingpcb production defects and component defects between electrical properties and electrical connections of online components. It mainly checks the on-line single component and the open and short circuit of each circuit network, and has the characteristics of simple operation, fast and accurate fault location. For high volume production, ICT is still the most common and economical test method available.
ICT equipment is divided into two types: probe bed type and flying probe type.
1. Probe bed ICT
The probe bed type ICT can detect high fault coverage, fast detection speed and high efficiency, but special probe bed clamps are required for each single board.Probe-bed ICT is suitable for general assembly density, high-volume pcb electronic products.
Figure 1 is the Beijing Xinghe SRC8001 needle bed ICT. The SRC8001 is a new generation of circuit board test equipment developed by Beijing Xinghe. The device has a PCB board graphic display function and photoelectric protection function. The ARM embedded processor is used to improve the test circuit board accuracy and stability; dual-channel high-speed synchronous acquisition technology greatly improves test speed; using four-pin eight-wire technology, using bridge test method to make micro-resistance test more stable; sensitive voltage sensing technology, can measure IC pin leakage solder open circuit, connectors, etc.; high test coverage and resolution, can measure optocouplers, potentiometers, connectors and other devices; can test flexible circuit boards (FPC boards), wires and soldering devices. In addition, it can be freely compatible and converted with the fixtures (needle beds) and programs of other mainstream ICT models on the market.
The probe has a diameter of 50 mil, 75 mil, 100 mil, etc., and the head shape has sharp, flat, rib, crown, circle, cluster, etc., as shown in FIG.
2. Flying probe type ICT
The open circuit test principle of the flying probe test and the test principle of the probe bed are basically the same.
The flying probe type ICT has 2 and 4 test heads. When tested, it is like a placement machine. It is automatically tested according to the pre-programmed program. The advantage is that the minimum spacing that can be tested is 0.2mm, the test accuracy is higher than the needle bed type ICT, the needle bed fixture is not required, and the program development time is short; the disadvantage is that the cost of the equipment is relatively high, and the test speed is relatively slow (100~200ms) Therefore, the flying needle type ICT is suitable for testing of multi-variety, medium and small batch, and high density pcb assembly boards. Figure 1 is a photograph of a flying probe ICT in a test.