When engineers develop or refine electronic products, their work often centers around BGA (Ball Grid Array) components. These devices are common candidates for modification, and we frequently receive two kinds of rework requests: removing a socketed BGA to solder it directly onto the board, or removing a soldered BGA to install it into a socket.
The second scenario—replacing a soldered BGA with a socket—presents a unique challenge. In most cases, the pads on the circuit board must be gold-plated before a socket can be installed. And when the BGA has over 1000 pads, that becomes no small task.
Figure 1 shows the original site of the BGA component, with exposed solder pads awaiting rework.
For plating to work reliably, each conductive pad needs an electrical connection. But how do you establish contact with more than a thousand tiny pads at once—and do it without exposing the rest of the board to harsh chemicals?
In this case, every BGA pad was connected to a plated via that passed through to the underside of the board. This made it possible to apply an innovative solution.
Here’s how we approached it:
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Conductive Ink Application
We applied a specially formulated, dissolvable conductive ink to the underside of the board, covering the targeted vias. Once applied, the ink was cured to create a temporary conductive layer. -
Establishing an Electrical Path
A buss wire was attached to the conductive ink area and connected to the cathode of the plating system, allowing current to flow through all the vias and up to the pads. -
Masking and Isolation
To protect the rest of the board, we used plating tape and removable masks. This ensured that only the BGA pad area was exposed to the plating process and that any excess solution had a controlled path for drainage. -
Solder Removal and Gold Plating
With preparation complete, we removed the residual solder and performed the gold plating. These steps are straightforward, but only when the setup is done correctly. -
Clean-Up and Final Inspection
Once the plating was complete, we removed the conductive ink and masking materials, then carried out a meticulous inspection to ensure that everything met the specifications.
Image 2 shows the final result: over 1000 perfectly gold-plated pads, ready for the next phase of assembly.
While it may appear simple at first glance, projects like these require a high level of precision and meticulous planning. Gold plating that many pads isn't just technical—it's a team effort, grounded in expertise and attention to detail.
