When we meet with FPC (flexible circuit board) have open circuit, the simplest way is to check the presence of line fault problem under a microscope, the line can be mostly through optical instrument can see, work to be met in many cases, however, under the microscope can’t check out the line of fracture problem, but with three measurement directly with meters gold fingers placed can be measured to open and the stand or fall of contact.
In fact, don’t be surprised by this result, because FPC is called flexible circuit board because it is soft and can be bent, which is the advantage and disadvantage of FPC, and the disadvantage is that it can be bent, because it may cause copper foil circuit fracture.
Although the copper foil is soft, repeated bending or reciprocating movement or impact is very likely to lead to its fracture. If the fracture is visible to the naked eye, it is easy to solve, because by observing the location of fracture, the cause of fracture can be generally known, and then countermeasures can be taken.
It is difficult to measure the on/off circuit from the gold finger at the end, but it is impossible to find the location of the fracture of the copper foil. If the location is not found, it is difficult to determine what causes the fracture, and usually a piecewise elimination method is adopted.
1. First, observe the faulty circuit with a microscope and mark the location of the suspected fracture.
2. If the microscope cannot find any suspected fracture location, the circuit can also be divided into several segments.
3. At both ends of the circuit where the circuit may break, or at the position of sections, carefully cut the outer protective film of the flexible plate with a blade. It is better to take a new art knife or carving knife, and then place the blade on the outer protective film to move left and right to scrape the outer protective film and expose the copper foil wire underneath.In this way, we can measure the circuit with three ammeters.Then, the possible fracture location can be eliminated step by step, and finally the exact fracture location of copper foil line can be found.
4. If you are worried that this method may break the copper foil circuit, you can also try to cut open the position where there is no copper foil next to the copper foil circuit, and then try to tear and peel off the outer protective film to achieve the same purpose.
Yongmingsheng is a Chinese PCB manufacturer, we produce: 1Layer FPC,2Layer FPC,Mutilayer FPC and so on, welcome to consult ~
Post time: Aug-12-2019