Component repair of motherboard?

Once all the layers of the motherboard have the traces then each one is precision drilled for the pass through that are pressed in the completed motherboard. Then all the layers are stacked and a process (some are proprietary) is used to compress and bind all the layers together.

Then all the pass through are pressed in the holes that were drilled earlier in the process. Some motherboards have layers that the pass through is put in before final assembly because they only go through two or more layers but not all. Once this process is complete then the motherboard is sealed.

The next step is to bind or solder all the components on the mother board, the smaller components such as support chips, resistors, caps, transistors (yes they still use transistors), and diodes.

The process uses wave soldering where the motherboard is subjected to liquid solder that adheres to the bare copper where the sealant is replaced with solder flux. Then the next step is putting on all the micro components such as the list above, this is done with robots that do what is called pick-and-place, then the solder under the component is melted and the component is secured.

The next step is non micro components such as the processor socket, the memory slots, add on card slots, the peripheral connectors (IDE, SATA, Floppy Drive, external connectors for keyboard, network, usb, sound, and firewire) and so on. Also any other items such as caps, switches, and other items.

The motherboard is complete, next the motherboard is tested, some manufactures use a jig that the memory, processor, and the peripherals are all simulated. Other manufactures use actual components to test the motherboard. The motherboard is connected up to a test station then powered up.

How long and how rigorous the motherboard is depends on the manufacture. The main thing is that the more rigorous the testing the less returns from dead on arrival (DOA) when the motherboards are sold.

"Component repair of main board, also know as low level component repair, removal and replacement of failed devices."

Component repair troubleshooting done? Ready to do the component repair of motherboard?

Ok, to do component repair you have the following tools –

• Variable wattage soldering iron (minimum twenty-five watts)
• Small tips for the soldering iron (as small as 1/16^th of an inch)
• Heavy duty heat sink (Must absorb up to 300 degrees F)
• A good magnifying glass
• A strong light
• Various electronics tweezers (angled and straight, spring loaded open or closed)
• Desoldering vacuum
• Desoldering copper weave

Now do you have the experience using the above list?

Any one can learn how to solder, takes a little practice to keep from melting the component and burning your fingers. What I am talking about is recognizing when the solder starts to melt, removing the heat and the component at the same time. Then heating the solder to the point where you can put the new component back with out destroying it?

Here is something a lot of people don’t know – the motherboard will start to degenerate when the temperature reaches 425 degrees F. That is the binding that the manufacture used when the motherboard layers were pressed together will start to separate, if the separation happens to be where there is a pass though then the motherboard is effectively destroyed. That is the reason for the heat sink that will absorb the heat that will spread while you are soldering.

Component repair

If you are replacing a large component such as a cap or a resistor or a socket then it is fairly easy. Just keep the heat from building up and causing the layers or traces from separating. But the small components are the hard part.

To remove a micro resistor or cap then you have to insure that the heat stays local to the spot you are working on. You only apply the heat to the failed component, and this is important, you only heat an area twice. Once to remove the failed component and once to solder the new component.

Note: If you have to remove a part and replace it a second time after removing the old part clean all the old solder and flux off the PCB area you are working in, then apply a small amount of new flux to the contact pads or pass through holes. New flux will allow the solder to flow easier with less heat. Old flux will build up and create a heat barrier to the solder joint, making for a bad or "cold" solder joint that will fail.

That takes care of the easy part. You know the component failed by seeing it is brunt, or in the case of a bad cap it exploded. Or you did a test and found the failed component by lack of voltage or resistance.

Now comes the hard parts-

How do you repair a trace that has lifted from the motherboard?

Answer: You can’t, once the trace lifts the only thing you can do is to "by pass" the part that has lifted with a thin gage insulated wire.

You would do this by finding two points where the trace is wide enough to accommodate the small gage wire.

I will warn you do not use a pass through to put the wire in. Why? The heat that the solder will produce may cause the pass through to separate from the traces inside the motherboard, may even cause the motherboard to ‘bubble’ around the pass through.

You would use an Exacto knife or thin razor blade knife to careful scrape off the sealant. Cut the bad trace just past the places where you scraped of the sealant. Heat and apply solder to both ends of the wire only. Apply flux to the trace where the sealant was removed. 

Once the wire is tined then put one end of the wire on the scrapped trace and apply heat – just long enough to melt the solder, be careful with the heat the trace is all ready exposed and will not take much to separate it from the spot where the sealant has been removed. Solder both ends, then test the repair with an ohm meter. If it tests good then use some fingernail polish to reseal the solder points, you could use the polish to cover the wire and seal it to the PCB also.

You can do low level component repair but I will warn you that a component failure do to the component material failure is low. Something caused that component to fail, heat, voltage, or amperage above the component’s design specifications. You need to test further upstream before completing your repair or you will either have a lot of smoke or a fire.

There are more instructions for component repair in the   Self Computer Repair Unleashed! 2nd Edition..