E-test means electronic test, is used to test circuit boards for short circuit, disconnection (compared to netlist), capacitance, and resistance. And some report will be summarized by the test results, including cross-section, solderability, peel strength, etc. so that all the functions and the ideal performance of the bare board can be achieved in the actual project.
The importance of the PCB E-test
As the PCB designs become more complex and have smaller features on tighter grids, and the size of drill holes becomes smaller, the electronic test becomes more critical for PCB quality control. The days only relying on the visual inspection are gone, as visual inspection is only relatively practical on double-layer PCBs or multilayer PCBs before lamination. Nowadays, with the development of through-holes such as blind vias and buried vias, visual inspection is difficult to reach this that far.
It is believed that once the PCB is manufactured without errors, E-test is no longer necessary, which is a common mistake. Since the charge in each PCB production is a separate process, it is needed to test each PCB every time. Only E-test can identify incorrect and missing connections. After the PCBs pass E- test, the PCBs can be 100% used. E-test is the process to make sure all the PCBs are no short or open before delivery to customers or applying to the devices.
Two test methods for E-test
PCB manufacturers will check two main types of defaults during the test procedure: open circuits and short circuits. There are also other types of tests available, depending on the customers’ requirements. There are two ways of electronic tests.
1. Flying probe test
This method uses a flying probe testing machine to test the PCB connection network one by one. The freely programmable test pins directly check the pre-defined measurement points on the traces, pads, pins, and test pads for connection errors. This process saves the construction of the adapter, which reduces the cost for the customer. The time the test need generally is 1-3 minutes for one PCB. Flying probe test is suitable for prototype and small series of exposed boards. We can check each net to make sure that it is complete and does not short to any other network by using a flying probe tester. Flying probe testing is low-cost, short delivery time and does not need to do a fixed testing tool.
2. Bed of nails fixture test
This is a testing method that needs a PCB fixture testing machine. The disadvantage is there need to make a test fixture machine for each type of PCB, which is not economical for PCB prototype. But with flexible pins, fix tooling can simultaneously touch all the points that need to be electrically tested, and the testing time of one PCB usually is 5 to 10 seconds. This test method can greatly improve production efficiency and is more suitable for batch production.
NextPCB dedicates to provide PCB manufacturing services that meet customers' requirements and expectations with high quality. 100% of our PCBs will go through the electrical test at the end of the PCB production process. Please send Emails to us or contact the online service if you have other test requirements.