Volumes have been written on BGA rework, with most of those articles concentrating on the removal and replacement of parts. However, the subject of BGA site modification is also crucial, and it is frequently necessary to highlight it.
BGA site modification, one of the approaches of BGA rework, is a method typically used for engineering changes and modifications that can help restore the device for its best functioning and usage when a device is not functioning. BGA rework is crucial for maintaining and working the device or equipment when there is a problem with the BGA pad. The requirement of adding a jumper wire at the site of BGA is one of the most typical BGA site modifications. Running a jumper through a board hole is one possibility.
When it is a buried via, and there are no other options for terminating to the other side, this method is employed. To achieve a solid and reliable outcome, it is rather complex and must be done properly. Additionally, this technique needs highly skilled operators and precise milling machinery.
The BGA component removes the surface solder; the area is cleaned off and inspected. If everything is in order, the solder mask should be removed from the via pad connecting to the relevant BGA pad.
First, Cut or drill a hole through the printed circuit board at the precise coordinates using precision drill equipment and the correct end mill size. Cutting of inner layer traces of signals must be avoided, even though ground as well as power planes can both be severed. Examine and tidy up the place.
Next, put a Teflon sleeve of the right size into the machined hole. This sleeve will insulate the new conductor, preventing shorts to the inner layers.
Choose a circuit track that is flat and ribbon-shaped for the Teflon-sleeved hole. This replacement of circuit tracks is made of pure copper and comes in various sizes. For this use, a typical size might be.003" thick by.015" wide. Before moving on to the next stage, the endings of the circuit track should be soldered and tinned.
Put the end of the BGA Pad and circuit's track into the through or plated hole attached to the BGA pad. The other end should then be inserted into the Teflon sleeve. The process is to lap soldering of the circuit track with the help of liquid flux to plated hole linked to the BGA pad; remember to just use a small amount of liquid flux.
Clean the location entirely. The entire top and flanks of the new circuit should be coated with a high-strength, high-temperature epoxy mixture. The new circuit is insulated and is joined to the baseboard layer by epoxy. Make sure the epoxy height is lower than the BGA pad level.
Install the new BGA component, clean the board as necessary, and prepare the installation area. Then, after switching to the different side of the board, solder a jumper wire to expose the circuit track there, route it as necessary, and then terminate it.
When all else fails, the BGA rework and its method of BGA site modification are utilized. Although a bit complex, this is one option that should be taken into account.
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