Marcy’s Musings: Additive Processes, Signal Consequences
It’s Only Common Sense: Build Your Business on Reputation, Not Neglect
The Marketing Minute: If Your Marketing Budget Gets Cut in Half, Then What?
What is the effect of testing with a universal/dedicated four-wire tester?
In the actual testing process, all four-wire testers or special four-wire testers test the finished PCBs. Many PCB through-holes are covered with solder mask and hole-to-hole tests cannot be performed at all.
Figure 8: Line schematic.
Due to the limitations of fixtures such as dispensing needles, slope, and probe size, it is impossible to achieve 100% coverage in the process of testing fixtures, as shown in Figure 8, if both the C and S surfaces of the through-hole are solder mask plugged holes. There are two possibilities. One is that it cannot be tested using the four-wire method. Second, even if the four-wire method is used, it is a hole test method to increase the risk of leakage.
It can be seen that testing with a universal/dedicated four-wire tester cannot effectively test the hole. The hole-to-hole test method must be used for the hole defect.
Four-Wire Four-Terminal Flying Probe Testing Machine
A Four-wire, four-terminal flying needle machine has the following capabilities:
- Different gears correspond to different resolutions
- Test accuracy and repeatability control within 5%
- The minimum test is 0.4mΩ and the maximum test is 800KΩ
Figure 9: LTD flying probe tester.
Its parameters and actual testing capabilities are shown in Table 2:
Table 2: Parameters and test capabilities.
Page 3 of 4
