PCB flying pin test operation skills
This paper will share some skills in the operation of flying pin test, such as alignment, fixed frame, fork plate test and warping plate test, for reference only.
First of all, we need to talk about the selection of counterpoint. Generally, we only choose two diagonal holes as the counterpoint, (naturally, we need to select the edge, and we need to count the first few holes from the left when aligning?) instead of paying attention to IC. The advantage of this method is that there are few alignment points and less time for alignment. Generally speaking, there is always side corrosion in etching, so it is not accurate to select pad as alignment point. If there are many open circuits, you don't need to stop right away. When the open circuit test is finished and the short circuit test starts, you can stop again, because you can check the open circuit error at this time. You can add the corresponding point according to the error position reported.
When talking about manual alignment, strictly speaking, the holes are not in the center of the pad, so when aligning, do you want to put the points in the center of the pad as much as possible, or try to coincide with the real holes? Generally, if the points to be tested are mostly holes, select the latter, if they are mostly IC, especially when the IC is prone to false open circuit, you need to put the alignment holes in the middle of the pad.
2、 Fixed frame
The fixed frame is the fixed test bracket. The data with frame is represented by two boxes. The external box is the frame. For such a board, use the size given by the machine directly. For the data without frame, use a box. We can use show Board command (which will be used when looking at the direction of placing the board) is to see which pad is the closest to the edge of the board to be tested, and compare it with the actual board to see how far it is from the edge of the board, so as to compensate.
3、 To cross
For the panel, the selected single can be tested. We can use this function to test the panel whose distance from the pad to the edge of the panel is too small to be tested. The method is to cross the single panel whose pad is blocked by the tray and can't be tested. After the test, put the tray on the tested single fixed plate, and select the panel that was not tested last time, so that we can pass the test twice Test the whole board. Therefore, we should use the functions provided by the equipment flexibly to fulfill some special needs.
In one direction, the size is too large, especially in the other direction, when the board is placed on the testing machine, natural warpage (caused by gravity) will occur. However, our flying needle machine has a little problem in structure. In the X direction, the size is large, but only one plate bracket is placed, while in the Y direction, three plate brackets can be placed. Therefore, in the machine When choosing to set the rectangular direction of the board to be tested as the X direction of the machine, it is better to arrange it manually, rotate the board 90 degrees, and make its rectangular direction be placed in the Y direction, so as to solve the warpage problem of the board in the test to a certain extent. (this adjustment has to be handled in the DPS).