PCBs are necessary to do electric inspection after board manufacturing and assembling.
We are professional PCB manufacturer which have been focous on PCB over 10 years. We offer PCB one stop services worldwide, so we attach great importance to electric inspection,we use all-round inspection with good inspect method to increase the efficiency on PCBs.
The following are some measuring methods on PCBs,which will find out where short or open.
1. If it is manual welding, we should form good habits. First of all, Visual check the PCBs before welding, and use a multimeter to check the key circuit (especially the power and ground) whether short or not;
Secondly, when finishing welding a chip, we should use multimeter to check the power and ground whether they are short or not;
In addition, don’t use iron welding disorderly, because if the solder slide to welding feet of the chip (especially for the Surface-mount components),which is not easy to find out if the PCBs are short or not.
2. Open the PCB diagram on the computer, and highlight the short net, we need to find out the closest and likely to be connected position. Especially pay attention to IC internal short.
3. If we find there is short phenomenon. Please use one PCB board to cut circuit (especially for single and double side PCB), after cut the circuit, use every functional part to electrify, then, we can rule out one by one.
4. We suggest use short position analyzer, such as PROTEQCB2000 short-circuit tracking instrument from Singapore, Hong Kong soul technology QT50 short-circuit tracking device, and the British POLARToneOhm950 professional way short circuit detector, etc.
5. If there is BGA chip, because of all the solder points are covered by chips so we can not see, what is more, if there are multilayer PCB(more than 4 layer), we suggest when doing PCB design , it’s better to separate the chip and power, and use bead and resistance(0 ohm) to connect. Then, if power and ground is short, we can disconnect bead, which is easy to position which chip is short. Because it’s not easy to solder BGA, if it’s not soldered by machine, adjacent power and ground solder balls will be short easily.
6. Small size of the Surface-mount capacitance must be careful when welding, especially the power filter capacitor (103 or 104), if the quantity is large, it is easy to cause the power and ground short.Of course, sometimes bad luck, will meet capacitance itself is short, so it is better to test the capacitance first before welding.
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