How to check the short circuit in PCB during PCB design, you can take the following important steps to check the short circuit in PCB: 1. 2. Test circuit short circuit on the circuit board; 3. Find the faulty components on PCB; 4. Test the PCB destructively.

Step 1: How to find short circuit in PCB

Visually inspect the

The first step is to look carefully at the entire surface of the PCB. If so, use a magnifying glass or low power microscope. Look for tin whiskers between pads or solder joints. Any cracks or spots in the solder should be noted. Check all through-holes. If unplated through holes are specified, make sure this is the case on the board. Poorly plated through-holes can cause a short circuit between layers and make everything you have grounded, VCC or both tied together. If the short circuit is really bad and causes the component to reach a critical temperature, you will actually see burn spots on the printed circuit board. They may be small, but turn brown instead of the normal green flux. If you have multiple boards, a burned PCB can help you narrow down a particular location without having to power another board, so as not to sacrifice search range. Unfortunately, there were no burns on our circuit board itself, just unlucky fingers checking to see if the INTEGRATED circuit was overheating. Some short circuits will occur inside the board and will not generate combustion points. This also means they don’t attract attention on the surface layer. At this point, you will need other methods to detect short circuits in the PCB.

Infrared imaging

Using an infrared thermal imager can help you locate areas that generate a lot of heat. If the active component is not seen moving away from the hot spot, a PCB short circuit may occur even if it occurs between the inner layers. Short circuits generally have higher resistance than normal wiring or solder joints because it has no benefit of optimization in design (unless you really want to ignore rule checking). This resistance, as well as the natural high current generated by the direct connection between the power supply and ground, means that the conductor in a PCB short circuit heats up. Start with a low current that you can use. Ideally, you’ll see a short circuit before you do more damage.

A finger test is a way to check if a particular component is overheating

Step 2: How do I test for short circuits on the electronic board

In addition to the first step of checking the board with a trusty eye, there are several other ways you can look for potential causes of PCB short-circuits.

Test with a digital multimeter

To test the circuit board for short-circuiting, check the resistance between different points in the circuit. If visual inspection does not reveal any clues as to the location or cause of the short circuit, grab the multimeter and try to trace the physical location on the printed circuit board. The multimeter approach has received mixed reviews in most electronics forums, but tracking test points can help you identify problems. You will need a very good multimeter with milliohm sensitivity, which is easiest if it has a buzzer function to alert you when detecting short circuits. For example, high resistance should be measured if resistance is measured between adjacent wires or pads on a PCB. If the resistance measured between two conductors that should be in a separate circuit is very low, the two conductors may be bridged internally or externally. Note that two adjacent wires or pads bridged with an inductor (for example in impedance matching networks or discrete filter circuits) will produce a very low resistance reading because the inductor is only a coil conductor. However, if the conductors on the board are far apart, and the resistance you read is small, there will be a bridge somewhere on the board.

Relative to the ground test

Of particular importance are short circuits involving ground holes or ground layers. Multi-layer PCBS with internal grounding will include a return path through the assembly near the hole, providing a convenient location to inspect all other holes and pads on the surface layer of the board. Place one probe on the ground connection and touch the other probe on the other conductor on the board. The same ground connection will exist elsewhere on the board, which means that if each probe is placed in contact with two different ground perholes, the reading will be small. Be careful with your layout when doing this, because you do not want to mistake a short circuit for a common ground connection. All other ungrounded bare conductors shall have high resistance between the common ground connection and the conductor itself. If the values read are low and there is no inductance between the conductor in question and the ground, component damage or short circuiting may be the cause.

Multimeter probes can help you find short paths, but they are not always sensitive enough to find short paths.

Short circuit components

To check whether the component is short-circuited, use a multimeter to measure the resistance.If visual inspection does not reveal excessive solder or sheet metal between pads, there may be a short circuit in the inner layer between two pads/pins on the assembly. Short circuits may also occur between pads/pins on assemblies due to poor manufacturing. This is one of the reasons the PCB should be checked for DFM and design rules. Pads and holes that are too close together can be accidentally bridged or short-circuited during manufacturing. Here, you need to measure the resistance between the pins on the IC or connector. Adjacent pins are particularly prone to short-circuiting, but these are not the only places where short-circuiting can occur. Check that the resistance between pads/pins is relative to each other and that the ground connection has low resistance.

Check the resistance between the ground seat, connector and other pins on the IC. The USB connector is shown here.

Narrow location

If you think there is a short circuit between two conductors or between a conductor and the ground, you can narrow down the location by checking nearby conductors. Connect one lead of the multimeter to the suspected short-circuit connection, move the other lead to a different grounding connection nearby, and check the resistance. As you move farther to the ground point, you should see a change in resistance. If resistance increases, you are moving the grounded wire away from the short-circuit position. This helps you narrow down the exact location of the short circuit, even to a specific pair of pads/pins on the component.

Step 3: How do I find faulty components on the PCB

Faulty components or improperly installed components can cause a short circuit, which can cause many problems on the board. Your components may be defective or forged, causing short circuits or short circuits.

Adverse element

Some components are susceptible to deterioration, such as electrolytic capacitors. If you have suspicious components, check those components first. If in doubt, you can often do a quick Google search for components suspected of “failing” to find out if this is a common problem. If you measure very low resistance between two pads/pins (neither of which are ground or power pins), you may short out due to burnt out components. This is a clear indication that the capacitor has been broken. The capacitor also expands once it deteriorates or the voltage applied exceeds the breakdown threshold.

See the bump on the top of this capacitor? This indicates that the capacitor has been damaged.

Step 4: How do I destructively test a PCB

Destructive testing is obviously a last resort. If you can use an X-ray imaging device, you can look inside the circuit board without damaging it. In the absence of an X-ray device, you can start removing components and running multimeter tests again. This helps in two ways. First, it gives you easier access to pads (including thermal pads) that may short-circuit. Second, it eliminates the possibility of a fault causing a short circuit, allowing you to focus on the conductor. If you try to narrow down to where the short circuit is connected on the component (for example, between two pads), it may not be obvious whether the component is defective or whether a short circuit is found somewhere inside the board. At this point, you may need to remove the assembly and check the pads on the board. Removing the assembly allows you to test whether the assembly itself is defective or whether the pads on the board are internally bridged.

If the location of the short circuit (or possibly multiple short circuits) remains elusive, cut the board and try to narrow it down. If you have some idea of where a short circuit is in general, cut a section of the board and repeat the multimeter test in that section. At this point, you can repeat the above tests with a multimeter to check for short circuits at specific locations. If you’ve reached this point, your shorts have been particularly elusive. This will at least allow you to narrow the short circuit to a specific area of the board.