1.Ad-hoc Testing Technology
Target specific testability design technology (Ad-hoc) is an early DFT technology that addresses testing problems in an already formed PCB design. The main technology of the basic idea is: to access the internal circuit by adding a selector, to enhance its controllability and observability; add logic gate circuit to control the total circuit to increase the controllability; increase the observation points in need of the landlord.

2. scan technique
PCB generally includes two parts: temporal logic and combinational logic. Combinational logic enables existing testing techniques to better test generation, while sequential logic circuits are difficult to obtain sufficiently satisfactory test programs because sequential circuits are often complex. Scan with automatic test pattern generation technique, the sequential elements difficult to test in the circuit can be transformed to the scanning unit serial input and output, so as to test the perspective of increasing many control points and observation points, greatly improves the PCB observability.

3. built in self test (BIST)
The basic idea of built in self-test design is that the test vectors are not required to be generated by external products, and the test vectors are generated by the circuits themselves, and the test results are determined by themselves. This approach involves the integration of a small number of logic circuits within the PCB to test the integrated circuit. With the improvement of integration, integrated circuit engineering is no longer concerned with the circuit or chip area occupied by BIST logic. Therefore, the built-in self-test design technology is widely used in modern integrated circuits. This testing method is considered as one of the effective methods to solve the long and costly development of testing instruments.