What is the flying probe test of the circuit board? What does it do? This article will give you a detailed description of the flying probe test of the circuit board, as well as the principle of the flying probe test and the factors that cause the hole to be blocked. Present.
The principle of the circuit board flying probe test is very simple. It only needs two probes to move x, y, z to test the two end points of each circuit one by one, so there is no need to make additional expensive fixtures. However, because it is an end point test, the test speed is extremely slow, about 10-40 points/sec, so it is more suitable for samples and small mass production; in terms of test density, flying probe test can be applied to very high density boards, such as MCM.
The principle of the flying probe tester: It uses 4 probes to conduct high-voltage insulation and low-resistance continuity test (testing the open circuit and short circuit of the circuit) on the circuit board, as long as the test file is composed of the customer manuscript and our engineering manuscript.
There are four reasons for short circuit and open circuit after the test:
1. Customer files: the test machine can only be used for comparison, not analysis
2. Production line production: PCB board warpage, solder mask, irregular characters
3. Process data conversion: our company adopts engineering draft test, some data (via) of engineering draft is omitted
4. Equipment factor: software and hardware problems
When you received the board that we tested and passed the patch, you encountered the via hole failure. I don’t know what caused the misunderstanding that we could not test it and shipped it. In fact, there are many reasons for the via hole failure.
There are four reasons for this:
1. Defects caused by drilling: the board is made of epoxy resin and glass fiber. After drilling through the hole, there will be residual dust in the hole, which is not cleaned, and the copper cannot be sinked after curing. Generally, we are flying needle testing in this case The link will be tested.
2. Defects caused by copper sinking: the copper sinking time is too short, the hole copper is not full, and the hole copper is not full when the tin is melted, resulting in bad conditions. (In the chemical copper precipitation, there are problems in the process of removing slag, alkaline degreasing, micro-etching, activation, acceleration, and copper sinking, such as incomplete development, excessive etching, and the residual liquid in the hole is not washed clean. The specific link is specific analysis)
3. The circuit board vias require excessive current, and the need to thicken the hole copper is not notified in advance. After the power is turned on, the current is too large to melt the hole copper. This problem often occurs. The theoretical current is not proportional to the actual current. As a result, the copper of the hole was melted directly after power-on, which caused the via to be blocked and was mistaken for not being tested.
4. Defects caused by SMT tin quality and technology: The residence time in the tin furnace is too long during welding, which causes the hole copper to melt, which causes defects. Novice partners, in terms of control time, the judgment of materials is not very accurate , Under the high temperature, there is a mistake under the material, which causes the hole copper to melt and fail. Basically, the current board factory can do the flying probe test for the prototype, so if the plate is made 100% flying probe test, to avoid the board receiving the hand to find problems. The above is the analysis of the flying probe test of the circuit board, I hope to help everyone.