PCB (printed circuit board) short circuit inspection methods
1, if a manual welding, to develop good habits, first of all, before soldering PCB(printed circuit board )visual inspection again and check the key circuit with a multimeter (especially power and ground) is short; Second, each time a chip to finish welding multimeter test the power and ground are shorted; In addition, the soldering iron do not make rejection, if the chip solder welding flung feet (especially the surface-mount components), not easily found.
2, open PCB diagram on the computer, light short-circuit network, where to look away from the most recent, most likely to be connected to the piece. With particular attention to the internal IC circuit.
3, found that short circuit. Take a piece of board to cuts (especially for single / double board), secant, respectively, after each part of the power block, some part of the excluded.
4, the use of short positioning analyzer, such as: Singapore PROTEQCB2000 short tracker, the Hong Kong Smart Technology QT50 short tracker, MLB Road British POLARToneOhm950 short detector and so on.
5, if there BGA chip, chip, because all joints are covered can not see, and it is the multilayer (Layer 4 and above), so the best chips in the design of the power of each separate, with beads or 0 Euro resistor connected, so that the power and ground short circuit occurs, disconnect the bead test, it is easy to navigate to a particular chip. Since BGA welding is difficult, if not automatic welding machine, little attention will be the two adjacent power and ground ball short.
6, the small size of the surface-mount capacitors must be careful when soldering, especially the power supply filter capacitor (103 or 104), quantity, is likely to cause short-circuit power and ground. Of course, sometimes bad luck, will encounter capacitor itself is short, so the best way is to weld it again before the first capacitive detection.