Surface Mount Repairs

I tend to enjoy delicate and detailed work. It is a challenge, and to me, that is what makes it fun. I treat surface mount component repair like surgery, using dental probes, and isopropyl, and cotton swabs... This, in combination with my self taught medical advice, has earned me a bit of a reputation at work as a Doctor. Not to mention the fairly well known fact that I like to collect medical items at home as well. My medical exam table is one such item, as well as my EKG monitors. In any case, this post is about some typical electronic component repairs I tend to do on a regular basis.

Working with small SMD chips can be intimidating. A hot air rework station is highly recommended, as trying to solder and desolder multi-pin chips such as this with a soldering iron, would be tricky, if not frustrating. In the above photo, I am cleaning up the pads for a LUCENT L9215AAU telephone interface chip. The board is a 4 port FXS board (P/N 08215130100) which is part of an old Intel VoIP gateway (P/N E808S8PORTFXS). In the application we utilize these devices, they sometimes get exposed to lightning discharges. Usually the circuit protection quenches the spikes, but sometimes the chips do get hit, and need to be replaced. Replacing them is usually a fairly simple task with the rework station.

Typically after removing the old chip, the pads should be cleaned and inspected. Fresh solder should be added so that there is something for the new chip to adhere to. The new chips curled legs should also be tinned slightly with new solder, being careful not to leave any solder bridging the space between pins before you install the chip.

The above photos are taken using a magnifying glass installed in a work lamp. This is typically how I preform this work, as it is often too tiny to work with reliably with your naked eye. Must be sure to clear all solder, and ensure that the PCB pads are all still in place, before reinstalling the new chip. In the above photo, you may notice one pad missing. This was from a previous repair, however that pad isn't used or connected to any other devices, so I am not worrying about its absence.

With the chip replaced, the board is ready for service again. Note: I also fixed the small ceramic caps which had been slightly pushed off their pads from a previous repair.